The impact of progressive overload on the proportion and frequency of positive cardio-respiratory fitness responders
- Bell, Leo, McNicol, Ashleigh, McNeil, Elizabeth, Nguyen, Huy, Hunter, Jayden, O'Brien, Brendan
- Authors: Bell, Leo , McNicol, Ashleigh , McNeil, Elizabeth , Nguyen, Huy , Hunter, Jayden , O'Brien, Brendan
- Date: 2023
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 26, no. 10 (2023), p. 561-563
- Full Text:
- Reviewed:
- Description: The proportion of individuals whose cardio-respiratory fitness change after endurance training does not exceed the test's measurement error can be 40 %. We determined if progressively increasing treadmill run intensity compared to maintaining the same run intensity, improved the responder proportion to a 6-week 20-minute treadmill training regimen. The intervention response standard deviation method estimated the proportion of responders attributable to progressively increasing run intensity. The mixed-effects model demonstrated V̇O2 peak improved significantly more in the progressive versus constant run intensity group. The proportion of V̇O2 peak responses above the smallest worthwhile change attributable to progressively increasing run intensity was 63.6 %. © 2023 The Author(s)
- Authors: Bell, Leo , McNicol, Ashleigh , McNeil, Elizabeth , Nguyen, Huy , Hunter, Jayden , O'Brien, Brendan
- Date: 2023
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 26, no. 10 (2023), p. 561-563
- Full Text:
- Reviewed:
- Description: The proportion of individuals whose cardio-respiratory fitness change after endurance training does not exceed the test's measurement error can be 40 %. We determined if progressively increasing treadmill run intensity compared to maintaining the same run intensity, improved the responder proportion to a 6-week 20-minute treadmill training regimen. The intervention response standard deviation method estimated the proportion of responders attributable to progressively increasing run intensity. The mixed-effects model demonstrated V̇O2 peak improved significantly more in the progressive versus constant run intensity group. The proportion of V̇O2 peak responses above the smallest worthwhile change attributable to progressively increasing run intensity was 63.6 %. © 2023 The Author(s)
Telomere length maintenance and cardio-metabolic disease prevention through exercise training
- Denham, Joshua, O'Brien, Brendan, Charchar, Fadi
- Authors: Denham, Joshua , O'Brien, Brendan , Charchar, Fadi
- Date: 2016
- Type: Text , Journal article , Review
- Relation: Sports Medicine Vol. 46, no. 9 (2016), p. 1213-1237
- Relation: http://purl.org/au-research/grants/nhmrc/1009490
- Full Text:
- Reviewed:
- Description: Telomeres are tandem repeat DNA sequences located at distal ends of chromosomes that protect against genomic DNA degradation and chromosomal instability. Excessive telomere shortening leads to cellular senescence and for this reason telomere length is a marker of biological age. Abnormally short telomeres may culminate in the manifestation of a number of cardio-metabolic diseases. Age-related cardio-metabolic diseases attributable to an inactive lifestyle, such as obesity, type 2 diabetes mellitus and cardiovascular disease, are associated with short leukocyte telomeres. Exercise training prevents and manages the symptoms of many cardio-metabolic diseases whilst concurrently maintaining telomere length. The positive relationship between exercise training, physical fitness and telomere length raises the possibility of a mediating role of telomeres in chronic disease prevention via exercise. Further elucidation of the underpinning molecular mechanisms of how exercise maintains telomere length should provide crucial information on how physical activity can be best structured to combat the chronic disease epidemic and improve the human health span. Here, we synthesise and discuss the current evidence on the impact of physical activity and cardiorespiratory fitness on telomere dynamics. We provide the molecular mechanisms with a known role in exercise-induced telomere length maintenance and highlight unexplored, alternative pathways ripe for future investigations.
- Authors: Denham, Joshua , O'Brien, Brendan , Charchar, Fadi
- Date: 2016
- Type: Text , Journal article , Review
- Relation: Sports Medicine Vol. 46, no. 9 (2016), p. 1213-1237
- Relation: http://purl.org/au-research/grants/nhmrc/1009490
- Full Text:
- Reviewed:
- Description: Telomeres are tandem repeat DNA sequences located at distal ends of chromosomes that protect against genomic DNA degradation and chromosomal instability. Excessive telomere shortening leads to cellular senescence and for this reason telomere length is a marker of biological age. Abnormally short telomeres may culminate in the manifestation of a number of cardio-metabolic diseases. Age-related cardio-metabolic diseases attributable to an inactive lifestyle, such as obesity, type 2 diabetes mellitus and cardiovascular disease, are associated with short leukocyte telomeres. Exercise training prevents and manages the symptoms of many cardio-metabolic diseases whilst concurrently maintaining telomere length. The positive relationship between exercise training, physical fitness and telomere length raises the possibility of a mediating role of telomeres in chronic disease prevention via exercise. Further elucidation of the underpinning molecular mechanisms of how exercise maintains telomere length should provide crucial information on how physical activity can be best structured to combat the chronic disease epidemic and improve the human health span. Here, we synthesise and discuss the current evidence on the impact of physical activity and cardiorespiratory fitness on telomere dynamics. We provide the molecular mechanisms with a known role in exercise-induced telomere length maintenance and highlight unexplored, alternative pathways ripe for future investigations.
Four weeks of sprint interval training improves 5-km run performance
- Denham, Joshua, Feros, Simon, O'Brien, Brendan
- Authors: Denham, Joshua , Feros, Simon , O'Brien, Brendan
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 29, no. 8 (2015), p. 2137-2141
- Full Text:
- Reviewed:
- Description: Sprint interval training (SIT) rapidly improves cardiorespiratory fitness but demands less training time and volume than traditional endurance training. Although the health and fitness benefits caused by SIT have received considerable research focus, the effect of short-term SIT on 5-km run performance is unknown. Thirty healthy untrained participants (aged 18-25 years) were allocated to a control (n = 10) or a SIT (n = 20) group. Sprint interval training involved 3-8 sprints at maximal intensity, 3 times a week for 4 weeks. Sprints were progressed to 8 by the 12th session. All participants completed a 5-km time trial on a public running track and an incremental treadmill test in an exercise physiology laboratory to determine 5-km run performance and maximum oxygen uptake, respectively, before and after the 4-week intervention. Relative to the controls, sprint interval-trained participants improved 5-km run performance by 4.5% (p < 0.001), and this was accompanied by improvements in absolute and relative maximum oxygen uptake (4.9%, p 0.04 and 4.5%, p = 0.045, respectively). Therefore, short-term SIT significantly improves 5-km run performance in untrained young men. We believe that SIT is a time-efficient means of improving cardiorespiratory fitness and 5-km endurance performance. © 2015 National Strength and Conditioning Association.
- Authors: Denham, Joshua , Feros, Simon , O'Brien, Brendan
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 29, no. 8 (2015), p. 2137-2141
- Full Text:
- Reviewed:
- Description: Sprint interval training (SIT) rapidly improves cardiorespiratory fitness but demands less training time and volume than traditional endurance training. Although the health and fitness benefits caused by SIT have received considerable research focus, the effect of short-term SIT on 5-km run performance is unknown. Thirty healthy untrained participants (aged 18-25 years) were allocated to a control (n = 10) or a SIT (n = 20) group. Sprint interval training involved 3-8 sprints at maximal intensity, 3 times a week for 4 weeks. Sprints were progressed to 8 by the 12th session. All participants completed a 5-km time trial on a public running track and an incremental treadmill test in an exercise physiology laboratory to determine 5-km run performance and maximum oxygen uptake, respectively, before and after the 4-week intervention. Relative to the controls, sprint interval-trained participants improved 5-km run performance by 4.5% (p < 0.001), and this was accompanied by improvements in absolute and relative maximum oxygen uptake (4.9%, p 0.04 and 4.5%, p = 0.045, respectively). Therefore, short-term SIT significantly improves 5-km run performance in untrained young men. We believe that SIT is a time-efficient means of improving cardiorespiratory fitness and 5-km endurance performance. © 2015 National Strength and Conditioning Association.
Genome-wide sperm DNA methylation changes after 3 months of exercise training in humans
- Denham, Joshua, O'Brien, Brendan, Harvey, Jack, Charchar, Fadi
- Authors: Denham, Joshua , O'Brien, Brendan , Harvey, Jack , Charchar, Fadi
- Date: 2015
- Type: Text , Journal article
- Relation: Epigenomics Vol. 7, no. 5 (2015), p. 717-731
- Full Text:
- Reviewed:
- Description: Aim: DNA methylation programs gene expression and is involved in numerous biological processes. Accumulating evidence supports transgenerational inheritance of DNA methylation changes in mammals via germ cells. Our aim was to determine the effect of exercise on sperm DNA methylation. Materials & methods: Twenty-four men were recruited and assigned to an exercise intervention or control group. Clinical parameters were measured and sperm samples were donated by subjects before and after the 3-month time-period. Mature sperm global and genome-wide DNA methylation was assessed using an ELISA assay and the 450K BeadChip (Illumina). Results: Global and genome-wide sperm DNA methylation was altered after 3 months of exercise training. DNA methylation changes occurred in genes related to numerous diseases such as schizophrenia and Parkinson's disease. Conclusions: Our study provides the first evidence showing exercise training reprograms the sperm methylome. Whether these DNA methylation changes are inherited to future generations warrants attention.
- Authors: Denham, Joshua , O'Brien, Brendan , Harvey, Jack , Charchar, Fadi
- Date: 2015
- Type: Text , Journal article
- Relation: Epigenomics Vol. 7, no. 5 (2015), p. 717-731
- Full Text:
- Reviewed:
- Description: Aim: DNA methylation programs gene expression and is involved in numerous biological processes. Accumulating evidence supports transgenerational inheritance of DNA methylation changes in mammals via germ cells. Our aim was to determine the effect of exercise on sperm DNA methylation. Materials & methods: Twenty-four men were recruited and assigned to an exercise intervention or control group. Clinical parameters were measured and sperm samples were donated by subjects before and after the 3-month time-period. Mature sperm global and genome-wide DNA methylation was assessed using an ELISA assay and the 450K BeadChip (Illumina). Results: Global and genome-wide sperm DNA methylation was altered after 3 months of exercise training. DNA methylation changes occurred in genes related to numerous diseases such as schizophrenia and Parkinson's disease. Conclusions: Our study provides the first evidence showing exercise training reprograms the sperm methylome. Whether these DNA methylation changes are inherited to future generations warrants attention.
Increased expression of telomere-regulating genes in endurance athletes with long leukocyte telomeres
- Denham, Joshua, O'Brien, Brendan, Prestes, Priscilla, Brown, Nicholas, Charchar, Fadi
- Authors: Denham, Joshua , O'Brien, Brendan , Prestes, Priscilla , Brown, Nicholas , Charchar, Fadi
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Applied Physiology Vol. 120, no. 2 (2015), p. 148-158
- Relation: http://purl.org/au-research/grants/nhmrc/1009490
- Full Text:
- Reviewed:
- Description: Leukocyte telomeres shorten with age, and excessive shortening is associated with age-related cardiometabolic diseases. Exercise training may prevent disease through telomere length maintenance although the optimal amount of exercise that attenuates telomere attrition is unknown. Furthermore, the underlying molecular mechanisms responsible for the enhanced telomere maintenance observed in endurance athletes is poorly understood. We quantified the leukocyte telomere length and analyzed the expression of telomere-regulating genes in endurance athletes and healthy controls (both n = 61), using quantitative PCR. We found endurance athletes have significantly longer (7.1%, 208-416 nt) leukocyte telomeres and upregulated TERT (2.0-fold) and TPP1 (1.3-fold) mRNA expression compared with controls in age-adjusted analysis. The telomere length and telomere-regulating gene expression differences were no longer statistically significant after adjustment for resting heart rate and relative (V) over dotO(2 max) (all P > 0.05). Resting heart rate emerged as an independent predictor of leukocyte telomere length and TERT and TPP1 mRNA expression in stepwise regression models. To gauge whether volume of exercise was associated with leukocyte telomere length, we divided subjects into running and cycling tertiles (distance covered per week) and found individuals in the middle and highest tertiles had longer telomeres than individuals in the lowest tertile. These data emphasize the importance of cardiorespiratory fitness and exercise training in the prevention of biological aging. They also support the concept that moderate amounts of exercise training protects against biological aging, while higher amounts may not elicit additional benefits.
- Authors: Denham, Joshua , O'Brien, Brendan , Prestes, Priscilla , Brown, Nicholas , Charchar, Fadi
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Applied Physiology Vol. 120, no. 2 (2015), p. 148-158
- Relation: http://purl.org/au-research/grants/nhmrc/1009490
- Full Text:
- Reviewed:
- Description: Leukocyte telomeres shorten with age, and excessive shortening is associated with age-related cardiometabolic diseases. Exercise training may prevent disease through telomere length maintenance although the optimal amount of exercise that attenuates telomere attrition is unknown. Furthermore, the underlying molecular mechanisms responsible for the enhanced telomere maintenance observed in endurance athletes is poorly understood. We quantified the leukocyte telomere length and analyzed the expression of telomere-regulating genes in endurance athletes and healthy controls (both n = 61), using quantitative PCR. We found endurance athletes have significantly longer (7.1%, 208-416 nt) leukocyte telomeres and upregulated TERT (2.0-fold) and TPP1 (1.3-fold) mRNA expression compared with controls in age-adjusted analysis. The telomere length and telomere-regulating gene expression differences were no longer statistically significant after adjustment for resting heart rate and relative (V) over dotO(2 max) (all P > 0.05). Resting heart rate emerged as an independent predictor of leukocyte telomere length and TERT and TPP1 mRNA expression in stepwise regression models. To gauge whether volume of exercise was associated with leukocyte telomere length, we divided subjects into running and cycling tertiles (distance covered per week) and found individuals in the middle and highest tertiles had longer telomeres than individuals in the lowest tertile. These data emphasize the importance of cardiorespiratory fitness and exercise training in the prevention of biological aging. They also support the concept that moderate amounts of exercise training protects against biological aging, while higher amounts may not elicit additional benefits.
Acute exercise leads to regulation of Telomere-Associated genes and MicroRNA expression in immune Cells
- Chilton, Warrick, Marques, Francine, West, Jenny, Kannourakis, George, Berzins, Stuart, O'Brien, Brendan, Charchar, Fadi
- Authors: Chilton, Warrick , Marques, Francine , West, Jenny , Kannourakis, George , Berzins, Stuart , O'Brien, Brendan , Charchar, Fadi
- Date: 2014
- Type: Text , Journal article
- Relation: PloS One Vol. 9, no. 4 (2014), p. e92088
- Full Text:
- Reviewed:
- Description: Telomeres are specialized nucleoprotein structures that protect chromosomal ends from degradation. These structures progressively shorten during cellular division and can signal replicative senescence below a critical length. Telomere length is predominantly maintained by the enzyme telomerase. Significant decreases in telomere length and telomerase activity are associated with a host of chronic diseases; conversely their maintenance underpins the optimal function of the adaptive immune system. Habitual physical activity is associated with longer leukocyte telomere length; however, the precise mechanisms are unclear. Potential hypotheses include regulation of telomeric gene transcription and/or microRNAs (miRNAs). We investigated the acute exercise-induced response of telomeric genes and miRNAs in twenty-two healthy males (mean age = 24.1±1.55 years). Participants undertook 30 minutes of treadmill running at 80% of peak oxygen uptake. Blood samples were taken before exercise, immediately post-exercise and 60 minutes post-exercise. Total RNA from white blood cells was submitted to miRNA arrays and telomere extension mRNA array. Results were individually validated in white blood cells and sorted T cell lymphocyte subsets using quantitative real-time PCR (qPCR). Telomerase reverse transcriptase (TERT) mRNA (P = 0.001) and sirtuin-6 (SIRT6) (P<0.05) mRNA expression were upregulated in white blood cells after exercise. Fifty-six miRNAs were also differentially regulated post-exercise (FDR <0.05). In silico analysis identified four miRNAs (miR-186, miR-181, miR-15a and miR-96) that potentially targeted telomeric gene mRNA. The four miRNAs exhibited significant upregulation 60 minutes post-exercise (P<0.001). Telomeric repeat binding factor 2, interacting protein (TERF2IP) was identified as a potential binding target for miR-186 and miR-96 and demonstrated concomitant downregulation (P<0.01) at the corresponding time point. Intense cardiorespiratory exercise was sufficient to differentially regulate key telomeric genes and miRNAs in white blood cells. These results may provide a mechanistic insight into telomere homeostasis and improved immune function and physical health. Funding NHMRC
- Authors: Chilton, Warrick , Marques, Francine , West, Jenny , Kannourakis, George , Berzins, Stuart , O'Brien, Brendan , Charchar, Fadi
- Date: 2014
- Type: Text , Journal article
- Relation: PloS One Vol. 9, no. 4 (2014), p. e92088
- Full Text:
- Reviewed:
- Description: Telomeres are specialized nucleoprotein structures that protect chromosomal ends from degradation. These structures progressively shorten during cellular division and can signal replicative senescence below a critical length. Telomere length is predominantly maintained by the enzyme telomerase. Significant decreases in telomere length and telomerase activity are associated with a host of chronic diseases; conversely their maintenance underpins the optimal function of the adaptive immune system. Habitual physical activity is associated with longer leukocyte telomere length; however, the precise mechanisms are unclear. Potential hypotheses include regulation of telomeric gene transcription and/or microRNAs (miRNAs). We investigated the acute exercise-induced response of telomeric genes and miRNAs in twenty-two healthy males (mean age = 24.1±1.55 years). Participants undertook 30 minutes of treadmill running at 80% of peak oxygen uptake. Blood samples were taken before exercise, immediately post-exercise and 60 minutes post-exercise. Total RNA from white blood cells was submitted to miRNA arrays and telomere extension mRNA array. Results were individually validated in white blood cells and sorted T cell lymphocyte subsets using quantitative real-time PCR (qPCR). Telomerase reverse transcriptase (TERT) mRNA (P = 0.001) and sirtuin-6 (SIRT6) (P<0.05) mRNA expression were upregulated in white blood cells after exercise. Fifty-six miRNAs were also differentially regulated post-exercise (FDR <0.05). In silico analysis identified four miRNAs (miR-186, miR-181, miR-15a and miR-96) that potentially targeted telomeric gene mRNA. The four miRNAs exhibited significant upregulation 60 minutes post-exercise (P<0.001). Telomeric repeat binding factor 2, interacting protein (TERF2IP) was identified as a potential binding target for miR-186 and miR-96 and demonstrated concomitant downregulation (P<0.01) at the corresponding time point. Intense cardiorespiratory exercise was sufficient to differentially regulate key telomeric genes and miRNAs in white blood cells. These results may provide a mechanistic insight into telomere homeostasis and improved immune function and physical health. Funding NHMRC
Effects of a seven day overload-period of high-intensity training on performance and physiology of competitive cyclists
- Clark, Bradley, Costa, Vitor, O'Brien, Brendan, Guglielmo, Luiz, Paton, Carl
- Authors: Clark, Bradley , Costa, Vitor , O'Brien, Brendan , Guglielmo, Luiz , Paton, Carl
- Date: 2014
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 9, no. 12 (2014), p. art no. e115308
- Full Text:
- Reviewed:
- Description: Abstract Objectives Competitive endurance athletes commonly undertake periods of overload training in the weeks prior to major competitions. This investigation examined the effects of two seven-day high-intensity overload training regimes (HIT) on performance and physiological characteristics of competitive cyclists. Design The study was a matched groups, controlled trial. Methods Twenty-eight male cyclists (mean ± SD, Age: 33±10 years, Mass 74±7 kg, VO2 peak 4.7±0.5 L·min−1) were assigned to a control group or one of two training groups for seven consecutive days of HIT. Before and after training cyclists completed an ergometer based incremental exercise test and a 20-km time-trial. The HIT sessions were ~120 minutes in duration and consisted of matched volumes of 5, 10 and 20 second (short) or 15, 30 and 45 second (long) maximal intensity efforts. Results Both the short and long HIT regimes led to significant (p<0.05) gains in time trial performance compared to the control group. Relative to the control group, the mean changes (±90% confidence limits) in time-trial power were 8.2%±3.8% and 10.4%±4.3% for the short and long HIT regimes respectively; corresponding increases in peak power in the incremental test were 5.5%±2.7% and 9.5%±2.5%. Both HIT (short vs long) interventions led to non-significant (p>0.05) increases (mean ± SD) in VO2 peak (2.3%±4.7% vs 3.5%±6.2%), lactate threshold power (3.6%±3.5% vs 2.9%±5.3%) and gross efficiency (3.2%±2.4% vs 5.1%±3.9%) with only small differences between HIT regimes. Conclusions Seven days of overload HIT induces substantial enhancements in time-trial performance despite non-significant increases in physiological measures with competitive cyclists
- Authors: Clark, Bradley , Costa, Vitor , O'Brien, Brendan , Guglielmo, Luiz , Paton, Carl
- Date: 2014
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 9, no. 12 (2014), p. art no. e115308
- Full Text:
- Reviewed:
- Description: Abstract Objectives Competitive endurance athletes commonly undertake periods of overload training in the weeks prior to major competitions. This investigation examined the effects of two seven-day high-intensity overload training regimes (HIT) on performance and physiological characteristics of competitive cyclists. Design The study was a matched groups, controlled trial. Methods Twenty-eight male cyclists (mean ± SD, Age: 33±10 years, Mass 74±7 kg, VO2 peak 4.7±0.5 L·min−1) were assigned to a control group or one of two training groups for seven consecutive days of HIT. Before and after training cyclists completed an ergometer based incremental exercise test and a 20-km time-trial. The HIT sessions were ~120 minutes in duration and consisted of matched volumes of 5, 10 and 20 second (short) or 15, 30 and 45 second (long) maximal intensity efforts. Results Both the short and long HIT regimes led to significant (p<0.05) gains in time trial performance compared to the control group. Relative to the control group, the mean changes (±90% confidence limits) in time-trial power were 8.2%±3.8% and 10.4%±4.3% for the short and long HIT regimes respectively; corresponding increases in peak power in the incremental test were 5.5%±2.7% and 9.5%±2.5%. Both HIT (short vs long) interventions led to non-significant (p>0.05) increases (mean ± SD) in VO2 peak (2.3%±4.7% vs 3.5%±6.2%), lactate threshold power (3.6%±3.5% vs 2.9%±5.3%) and gross efficiency (3.2%±2.4% vs 5.1%±3.9%) with only small differences between HIT regimes. Conclusions Seven days of overload HIT induces substantial enhancements in time-trial performance despite non-significant increases in physiological measures with competitive cyclists
Exercise : Putting action into our epigenome
- Denham, Joshua, Marques, Francine, O'Brien, Brendan, Charchar, Fadi
- Authors: Denham, Joshua , Marques, Francine , O'Brien, Brendan , Charchar, Fadi
- Date: 2014
- Type: Text , Journal article
- Relation: Sports Medicine Vol. 44, no. 2 (2014), p. 189-209
- Relation: http://purl.org/au-research/grants/nhmrc/1009490
- Full Text:
- Reviewed:
- Description: Most human phenotypes are influenced by a combination of genomic and environmental factors. Engaging in regular physical exercise prevents many chronic diseases, decreases mortality risk and increases longevity. However, the mechanisms involved are poorly understood. The modulating effect of physical (aerobic and resistance) exercise on gene expression has been known for some time now and has provided us with an understanding of the biological responses to physical exercise. Emerging research data suggest that epigenetic modifications are extremely important for both development and disease in humans. In the current review, we summarise findings on the effect of exercise on epigenetic modifications and their effects on gene expression. Current research data suggest epigenetic modifications (DNA methylation and histone acetylation) and microRNAs (miRNAs) are responsive to acute aerobic and resistance exercise in brain, blood, skeletal and cardiac muscle, adipose tissue and even buccal cells. Six months of aerobic exercise alters whole-genome DNA methylation in skeletal muscle and adipose tissue and directly influences lipogenesis. Some miRNAs are related to maximal oxygen consumption (VO 2max) and VO2max trainability, and are differentially expressed amongst individuals with high and low VO2max. Remarkably, miRNA expression profiles discriminate between low and high responders to resistance exercise (miR-378, -26a, -29a and -451) and correlate to gains in lean body mass (miR-378). The emerging field of exercise epigenomics is expected to prosper and additional studies may elucidate the clinical relevance of miRNAs and epigenetic modifications, and delineate mechanisms by which exercise confers a healthier phenotype and improves performance. © 2013 Springer International Publishing Switzerland. Funded by NHMRC; National Health and Medical Research Council
The reliability of performance during computer-simulated varying gradient cycling time trials
- Clark, Bradley, Paton, Carl, O'Brien, Brendan
- Authors: Clark, Bradley , Paton, Carl , O'Brien, Brendan
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of Science and Cycling Vol. 3, no. 3 (2014), p. 29-33
- Full Text:
- Reviewed:
- Description: Ergometer based time trials are commonly used to assess performance changes due to training or other interventions. This investigation establishes the reliability of a novel computer simulated cycling time trial. Nineteen cyclists (age: 32 ± 12 years, mass 73 ± 11 kg, height 178 ± 5 cm) completed four time trials over a 20-km course which included numerous changes in gradient. The time trials were completed over a 4-week period in order to establish both short and long-term reliability. Performance time (mean ± SD) for trials one to four was 2265 ± 149 s, 2252 ± 153 s, 2236 ± 146 s and 2240 ± 154 s respectively; the corresponding power output for consecutive trials was 293 ± 35 W, 297 ± 36 W, 299 ± 35 W and 299 ± 35 W. The coefficient of variation (± 90% confidence limits) of performance for trials separated by 7, 14, 21 and 28 days was 1.1% (0.8% – 1.5%), 1.3% (1.1% – 1.9%), 1.3% (1.1% – 1.9%) and 1.5% (1.1% – 2.1%) respectively for time; the corresponding values for power output were 2.0% (1.5% – 2.7%), 2.3% (1.8% – 3.2%), 2.6% (2.0% – 3.6%) and 3.2% (2.5% – 4.5%). Further analysis based on rider ability indicated slower riders were less reliable than faster riders by a factor of ~1.1. Reliability of time trial performance diminishes with increasing time between trials. Additionally, faster riders show better reliability than slower riders over time. Researchers should consider the effect of time between trials and athlete ability when making conclusions about intervention effectiveness.
- Authors: Clark, Bradley , Paton, Carl , O'Brien, Brendan
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of Science and Cycling Vol. 3, no. 3 (2014), p. 29-33
- Full Text:
- Reviewed:
- Description: Ergometer based time trials are commonly used to assess performance changes due to training or other interventions. This investigation establishes the reliability of a novel computer simulated cycling time trial. Nineteen cyclists (age: 32 ± 12 years, mass 73 ± 11 kg, height 178 ± 5 cm) completed four time trials over a 20-km course which included numerous changes in gradient. The time trials were completed over a 4-week period in order to establish both short and long-term reliability. Performance time (mean ± SD) for trials one to four was 2265 ± 149 s, 2252 ± 153 s, 2236 ± 146 s and 2240 ± 154 s respectively; the corresponding power output for consecutive trials was 293 ± 35 W, 297 ± 36 W, 299 ± 35 W and 299 ± 35 W. The coefficient of variation (± 90% confidence limits) of performance for trials separated by 7, 14, 21 and 28 days was 1.1% (0.8% – 1.5%), 1.3% (1.1% – 1.9%), 1.3% (1.1% – 1.9%) and 1.5% (1.1% – 2.1%) respectively for time; the corresponding values for power output were 2.0% (1.5% – 2.7%), 2.3% (1.8% – 3.2%), 2.6% (2.0% – 3.6%) and 3.2% (2.5% – 4.5%). Further analysis based on rider ability indicated slower riders were less reliable than faster riders by a factor of ~1.1. Reliability of time trial performance diminishes with increasing time between trials. Additionally, faster riders show better reliability than slower riders over time. Researchers should consider the effect of time between trials and athlete ability when making conclusions about intervention effectiveness.
Do physical capacity and interchange rest periods influence match exercise-intensity profile in Australian football?
- Mooney, Mitchell, Cormack, Stuart, O'Brien, Brendan, Coutts, Aaron
- Authors: Mooney, Mitchell , Cormack, Stuart , O'Brien, Brendan , Coutts, Aaron
- Date: 2013
- Type: Text , Journal article
- Relation: International Journal of Sports Physiology and Performance Vol. 8, no. 2 (2013), p. 165-172
- Full Text:
- Reviewed:
- Description: Purpose: The purpose of this study was to determine if Yo-Yo Intermittent Recovery level 2 (Yo-Yo IR2) and the number of interchange rotations affected the match activity profile of elite Australian footballers. Method: Fifteen elite Australian footballers completed the Yo-Yo IR2 before the beginning of the season and played across 22 matches in which match activity profiles were measured via microtechnology devices containing a global positioning system (GPS) and accelerometer. An interchange rotation was counted when a player left the field and was replaced with another player. Yo-Yo IR2 results were further split into high and low groups. Results: Players match speed decreased from 1st to 4th quarter, while average-speed (m/min: P = .05) and low-speed activity (LSA, <15 km/h) per minute (LSA m/min; P = .06) significantly decreased in the 2nd half. Yo-Yo IR2 influenced the amount of m/min, high-speed running (HSR, >15 km/h) per minute (HSR m/min) and accelerometer load/min throughout the entire match. The number of interchanges significantly influenced the HSR m/min and m/min throughout the match except in the 2nd quarter. Furthermore, the low Yo-Yo IR2 group had significantly less LSA m/min in the 4th quarter than the high Yo-Yo IR2 group (92.2 vs 96.7 m/ min, P = .06). Conclusions: Both the Yo-Yo IR2 and number of interchanges contribute to m/min and HSR m/min produced by elite Australian footballers, affecting their match activity. However, while it appears that improved Yo-Yo IR2 performance prevents reductions in LSA m/min during a match, higher-speed activities (HSR m/min) and overall physical activity (m/min and load/min) are still reduced in the 4th quarter compared with the 1st quarter. © 2013 Human Kinetics, Inc.
- Description: 2003010859
- Authors: Mooney, Mitchell , Cormack, Stuart , O'Brien, Brendan , Coutts, Aaron
- Date: 2013
- Type: Text , Journal article
- Relation: International Journal of Sports Physiology and Performance Vol. 8, no. 2 (2013), p. 165-172
- Full Text:
- Reviewed:
- Description: Purpose: The purpose of this study was to determine if Yo-Yo Intermittent Recovery level 2 (Yo-Yo IR2) and the number of interchange rotations affected the match activity profile of elite Australian footballers. Method: Fifteen elite Australian footballers completed the Yo-Yo IR2 before the beginning of the season and played across 22 matches in which match activity profiles were measured via microtechnology devices containing a global positioning system (GPS) and accelerometer. An interchange rotation was counted when a player left the field and was replaced with another player. Yo-Yo IR2 results were further split into high and low groups. Results: Players match speed decreased from 1st to 4th quarter, while average-speed (m/min: P = .05) and low-speed activity (LSA, <15 km/h) per minute (LSA m/min; P = .06) significantly decreased in the 2nd half. Yo-Yo IR2 influenced the amount of m/min, high-speed running (HSR, >15 km/h) per minute (HSR m/min) and accelerometer load/min throughout the entire match. The number of interchanges significantly influenced the HSR m/min and m/min throughout the match except in the 2nd quarter. Furthermore, the low Yo-Yo IR2 group had significantly less LSA m/min in the 4th quarter than the high Yo-Yo IR2 group (92.2 vs 96.7 m/ min, P = .06). Conclusions: Both the Yo-Yo IR2 and number of interchanges contribute to m/min and HSR m/min produced by elite Australian footballers, affecting their match activity. However, while it appears that improved Yo-Yo IR2 performance prevents reductions in LSA m/min during a match, higher-speed activities (HSR m/min) and overall physical activity (m/min and load/min) are still reduced in the 4th quarter compared with the 1st quarter. © 2013 Human Kinetics, Inc.
- Description: 2003010859
Impact of neuromuscular fatigue on match exercise intensity and performance in elite Australian football
- Mooney, Mitchell, Cormack, Stuart, O'Brien, Brendan, Morgan, William, McGuigan, Mike
- Authors: Mooney, Mitchell , Cormack, Stuart , O'Brien, Brendan , Morgan, William , McGuigan, Mike
- Date: 2013
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 27, no. 1 (2013), p. 166-173
- Full Text:
- Reviewed:
- Description: Mooney, MG, Cormack, S, O'Brien, BJ, Morgan, WM, and McGuigan, M. Impact of neuromuscular fatigue on match exercise intensity and performance in elite Australian football. J Strength Cond Res 27(1): 166-173, 2013: This study aimed to quantify the influence of neuromuscular fatigue (NMF) via flight time to contraction time ratio (FT:CT) obtained from a countermovement jump (CMJ) on the relationships between yo-yo intermittent recovery (level 2) test (yo-yo IR2), match exercise intensity (high-intensity running [HIR] m·min-1 and Load·min-1) and Australian football (AF) performance. Thirty-seven data sets were collected from 17 different players across 22 elite AF matches. Each data set comprised an athlete's yo-yo IR2 score before the start of the season, match exercise intensity via global positioning system and on-field performance rated by coaches' votes and number of ball disposals. Each data set was categorized as normal (>92% baseline FT:CT, n = 20) or fatigued (<92% baseline FT:CT, n = 17) from a single CMJ performed 96 hours after the previous match. Moderation-mediation analysis was completed with yo-yo IR2 (independent variable), match exercise intensity (mediator), and AF performance (dependent variable) with NMF status as the conditional variable. Isolated interactions between variables were analyzed by Pearson's correlation and effect size statistics. The Yo-yo IR2 score showed an indirect influence on the number of ball disposals via HIR m·min-1 regardless of NMF status (normal FT:CT indirect effect = 0.019, p < 0.1, reduced FT:CT indirect effect = 0.022, p < 0.1). However, the yo-yo IR2 score only influenced coaches' votes via Load·min-1 in the nonfatigued state (normal: FT:CT indirect effect = 0.007, p <0.1, reduced: FT:CT indirect effect = -0.001, p > 0.1). In isolation, NMF status also reduces relationships between yo-yo IR2 and load·min-1, yo-yo IR2 and coaches votes, Load·min-1 and coaches' votes ([DELTA]r > 0.1). Routinely testing yo-yo IR2 capacity, NMF via FT:CT and monitoring Load·min-1 in conjunction with HIR m·min-1 as exercise intensity measures in elite AF is recommended. © 2013 National Strength and Conditioning Association.
- Description: 2003010830
- Authors: Mooney, Mitchell , Cormack, Stuart , O'Brien, Brendan , Morgan, William , McGuigan, Mike
- Date: 2013
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 27, no. 1 (2013), p. 166-173
- Full Text:
- Reviewed:
- Description: Mooney, MG, Cormack, S, O'Brien, BJ, Morgan, WM, and McGuigan, M. Impact of neuromuscular fatigue on match exercise intensity and performance in elite Australian football. J Strength Cond Res 27(1): 166-173, 2013: This study aimed to quantify the influence of neuromuscular fatigue (NMF) via flight time to contraction time ratio (FT:CT) obtained from a countermovement jump (CMJ) on the relationships between yo-yo intermittent recovery (level 2) test (yo-yo IR2), match exercise intensity (high-intensity running [HIR] m·min-1 and Load·min-1) and Australian football (AF) performance. Thirty-seven data sets were collected from 17 different players across 22 elite AF matches. Each data set comprised an athlete's yo-yo IR2 score before the start of the season, match exercise intensity via global positioning system and on-field performance rated by coaches' votes and number of ball disposals. Each data set was categorized as normal (>92% baseline FT:CT, n = 20) or fatigued (<92% baseline FT:CT, n = 17) from a single CMJ performed 96 hours after the previous match. Moderation-mediation analysis was completed with yo-yo IR2 (independent variable), match exercise intensity (mediator), and AF performance (dependent variable) with NMF status as the conditional variable. Isolated interactions between variables were analyzed by Pearson's correlation and effect size statistics. The Yo-yo IR2 score showed an indirect influence on the number of ball disposals via HIR m·min-1 regardless of NMF status (normal FT:CT indirect effect = 0.019, p < 0.1, reduced FT:CT indirect effect = 0.022, p < 0.1). However, the yo-yo IR2 score only influenced coaches' votes via Load·min-1 in the nonfatigued state (normal: FT:CT indirect effect = 0.007, p <0.1, reduced: FT:CT indirect effect = -0.001, p > 0.1). In isolation, NMF status also reduces relationships between yo-yo IR2 and load·min-1, yo-yo IR2 and coaches votes, Load·min-1 and coaches' votes ([DELTA]r > 0.1). Routinely testing yo-yo IR2 capacity, NMF via FT:CT and monitoring Load·min-1 in conjunction with HIR m·min-1 as exercise intensity measures in elite AF is recommended. © 2013 National Strength and Conditioning Association.
- Description: 2003010830
Longer leukocyte telomeres are associated with ultra-endurance exercise independent of cardiovascular risk factors
- Denham, Joshua, Nelson, Christopher, O'Brien, Brendan, Nankervis, Scott, Denniff, Matthew, Harvey, Jack, Marques, Francine, Codd, Veryan, Zukowska-Szczechowska, Ewa, Samani, Nilesh, Tomaszewski, Maciej, Charchar, Fadi
- Authors: Denham, Joshua , Nelson, Christopher , O'Brien, Brendan , Nankervis, Scott , Denniff, Matthew , Harvey, Jack , Marques, Francine , Codd, Veryan , Zukowska-Szczechowska, Ewa , Samani, Nilesh , Tomaszewski, Maciej , Charchar, Fadi
- Date: 2013
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 8, no. 7 (2013), p.
- Full Text:
- Reviewed:
- Description: Telomere length is recognized as a marker of biological age, and shorter mean leukocyte telomere length is associated with increased risk of cardiovascular disease. It is unclear whether repeated exposure to ultra-endurance aerobic exercise is beneficial or detrimental in the long-term and whether it attenuates biological aging. We quantified 67 ultra-marathon runners' and 56 apparently healthy males' leukocyte telomere length (T/S ratio) using real-time quantitative PCR. The ultra-marathon runners had 11% longer telomeres (T/S ratio) than controls (ultra-marathon runners: T/S ratio = 3.5±0.68, controls: T/S ratio = 3.1±0.41;
- Description: 2003011219
- Authors: Denham, Joshua , Nelson, Christopher , O'Brien, Brendan , Nankervis, Scott , Denniff, Matthew , Harvey, Jack , Marques, Francine , Codd, Veryan , Zukowska-Szczechowska, Ewa , Samani, Nilesh , Tomaszewski, Maciej , Charchar, Fadi
- Date: 2013
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 8, no. 7 (2013), p.
- Full Text:
- Reviewed:
- Description: Telomere length is recognized as a marker of biological age, and shorter mean leukocyte telomere length is associated with increased risk of cardiovascular disease. It is unclear whether repeated exposure to ultra-endurance aerobic exercise is beneficial or detrimental in the long-term and whether it attenuates biological aging. We quantified 67 ultra-marathon runners' and 56 apparently healthy males' leukocyte telomere length (T/S ratio) using real-time quantitative PCR. The ultra-marathon runners had 11% longer telomeres (T/S ratio) than controls (ultra-marathon runners: T/S ratio = 3.5±0.68, controls: T/S ratio = 3.1±0.41;
- Description: 2003011219
Oxygen uptake in maximal effort constant rate and interval running
- Pratt, Daniel, O'Brien, Brendan, Clark, Bradley
- Authors: Pratt, Daniel , O'Brien, Brendan , Clark, Bradley
- Date: 2013
- Type: Text , Journal article
- Relation: The Scientific World Journal Vol. 2013, no. (2013), p.
- Full Text:
- Reviewed:
- Description: This study investigated differences in average V̇O2 of maximal effort interval running to maximal effort constant rate running at lactate threshold matched for time. The average V̇O2 and distance covered of 10 recreational male runners (V̇O2 max: 4158 ± 390 mL·min-1) were compared between a maximal effort constant-rate run at lactate threshold (CRLT), a maximal effort interval run (INT) consisting of 2 min at V̇O2 max speed with 2 minutes at 50% of V̇O2 repeated 5 times, and a run at the average speed sustained during the interval run (CR submax). Data are presented as mean and 95% confidence intervals. The average V̇O2 for INT, 3451 (3269-3633) mL·min-1, 83% V̇O2 max, was not significantly different to CRLT, 3464 (3285-3643) mL·min-1, 84% V̇O2 max, but both were significantly higher than CR sub-max, 3464 (3285-3643) mL·min -1, 76% V̇O2 max. The distance covered was significantly greater in CLRT, 4431 (4202-3731) metres, compared to INT and CR sub-max, 4070 (3831-4309) metres. The novel finding was that a 20-minute maximal effort constant rate run uses similar amounts of oxygen as a 20-minute maximal effort interval run despite the greater distance covered in the maximal effort constant-rate run. © 2013 Daniel Pratt et al.
- Description: C1
- Authors: Pratt, Daniel , O'Brien, Brendan , Clark, Bradley
- Date: 2013
- Type: Text , Journal article
- Relation: The Scientific World Journal Vol. 2013, no. (2013), p.
- Full Text:
- Reviewed:
- Description: This study investigated differences in average V̇O2 of maximal effort interval running to maximal effort constant rate running at lactate threshold matched for time. The average V̇O2 and distance covered of 10 recreational male runners (V̇O2 max: 4158 ± 390 mL·min-1) were compared between a maximal effort constant-rate run at lactate threshold (CRLT), a maximal effort interval run (INT) consisting of 2 min at V̇O2 max speed with 2 minutes at 50% of V̇O2 repeated 5 times, and a run at the average speed sustained during the interval run (CR submax). Data are presented as mean and 95% confidence intervals. The average V̇O2 for INT, 3451 (3269-3633) mL·min-1, 83% V̇O2 max, was not significantly different to CRLT, 3464 (3285-3643) mL·min-1, 84% V̇O2 max, but both were significantly higher than CR sub-max, 3464 (3285-3643) mL·min -1, 76% V̇O2 max. The distance covered was significantly greater in CLRT, 4431 (4202-3731) metres, compared to INT and CR sub-max, 4070 (3831-4309) metres. The novel finding was that a 20-minute maximal effort constant rate run uses similar amounts of oxygen as a 20-minute maximal effort interval run despite the greater distance covered in the maximal effort constant-rate run. © 2013 Daniel Pratt et al.
- Description: C1
The relationship between physical capacity and match performance in elite Australian football : A mediation approach
- Mooney, Mitchell, O'Brien, Brendan, Cormack, Stuart, Coutts, Aaron, Berry, Jason, Young, Warren
- Authors: Mooney, Mitchell , O'Brien, Brendan , Cormack, Stuart , Coutts, Aaron , Berry, Jason , Young, Warren
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 14, no. 5 (2011), p. 447-452
- Full Text:
- Reviewed:
- Description: The aim of this study was to verify if yo-yo intermittent recovery test (level 2) (yo-yo IR2) score is linked to Australian football (AF) performance through match exercise intensity. Six week prospective study design. Twenty-one data sets were recorded from nine individual players that completed the yo-yo IR2, and played an Australian Football League match in the first five rounds of the 2010 season wearing a global positioning system (GPS) unit. Simple mediation modelling was used to analyse the inter-relationship between yo-yo IR2 score, match exercise intensity and AF performance. Playing position and experience were also incorporated into the model to identify conditional affects. A significant direct relationship was observed between yo-yo IR2 and number of ball disposals (p<0.1) and a significant indirect relationship was observed between yo-yo IR2 and number of ball disposals through distance travelled at high intensity (HIR mmin-1) (p<0.1). Moderation analysis showed that playing position affected the relationship between of yo-yo IR2 and HIR mmin-1 (p<0.1) and HIR mmin-1 and total ball disposals (p<0.1). Playing experience also significantly affected the relationship between HIR mmin-1 and total ball disposals. This study is the first to identify the effects of yo-yo IR2 on total ball disposals through HIR mmin-1 performed during AF matches, and that playing position and playing experience affect these interactions. © 2011 Sports Medicine Australia.
- Authors: Mooney, Mitchell , O'Brien, Brendan , Cormack, Stuart , Coutts, Aaron , Berry, Jason , Young, Warren
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 14, no. 5 (2011), p. 447-452
- Full Text:
- Reviewed:
- Description: The aim of this study was to verify if yo-yo intermittent recovery test (level 2) (yo-yo IR2) score is linked to Australian football (AF) performance through match exercise intensity. Six week prospective study design. Twenty-one data sets were recorded from nine individual players that completed the yo-yo IR2, and played an Australian Football League match in the first five rounds of the 2010 season wearing a global positioning system (GPS) unit. Simple mediation modelling was used to analyse the inter-relationship between yo-yo IR2 score, match exercise intensity and AF performance. Playing position and experience were also incorporated into the model to identify conditional affects. A significant direct relationship was observed between yo-yo IR2 and number of ball disposals (p<0.1) and a significant indirect relationship was observed between yo-yo IR2 and number of ball disposals through distance travelled at high intensity (HIR mmin-1) (p<0.1). Moderation analysis showed that playing position affected the relationship between of yo-yo IR2 and HIR mmin-1 (p<0.1) and HIR mmin-1 and total ball disposals (p<0.1). Playing experience also significantly affected the relationship between HIR mmin-1 and total ball disposals. This study is the first to identify the effects of yo-yo IR2 on total ball disposals through HIR mmin-1 performed during AF matches, and that playing position and playing experience affect these interactions. © 2011 Sports Medicine Australia.
Consecutive bouts of diverse contractile activity alter acute responses in human skeletal muscle
- Coffey, V. G., Pilegaard, H., Garnham, A. P., O'Brien, Brendan, Hawley, J. A.
- Authors: Coffey, V. G. , Pilegaard, H. , Garnham, A. P. , O'Brien, Brendan , Hawley, J. A.
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Applied Physiology Vol. 106, no. 4 (2009), p. 1187-1197
- Full Text:
- Reviewed:
- Description: We examined acute molecular responses in skeletal muscle to divergent exercise stimuli by combining consecutive bouts of resistance and endurance exercise. Eight men [22.9 ± 6.3 yr, body mass of 73.2 ± 4.5 kg, peak O2 uptake (V̇O2peak) of 54.0 ± 5.7 ml·kg-1·min-1] were randomly assigned to complete trials consisting of either resistance exercise (8 x 5 leg extension, 80% 1 repetition maximum) followed by a bout of endurance exercise (30 min cycling, 70% V̇O2peak) or vice versa. Muscle biopsies were obtained from the vastus lateralis at rest, 15 min after each exercise bout, and after 3 h of passive recovery to determine early signaling and mRNA responses. Phosphorylation of Akt and Akt1Ser473 were elevated 15 min after resistance exercise compared with cycling, with the greatest increase observed when resistance exercise followed cycling (∼55%; P < 0.01). TSC2-mTOR-S6 kinase phosphorylation 15 min after each bout of exercise was similar regardless of the exercise mode. The cumulative effect of combined exercise resulted in disparate mRNA responses. IGF-I mRNA content was reduced when cycling preceded resistance exercise (-42%), whereas muscle ring finger mRNA was elevated when cycling was undertaken after resistance exercise (∼52%; P < 0.05). The hexokinase II mRNA level was higher after resistance cycling (∼45%; P < 0.05) than after cycling-resistance exercise, whereas modest increases in peroxisome proliferator-activated receptor gamma coactivator-1α mRNA did not reveal an order effect. We conclude that acute responses to diverse bouts of contractile activity are modified by the exercise order. Moreover, undertaking divergent exercise in close proximity influences the acute molecular profile and likely exacerbates acute "interference." Copyright © 2009 the American Physiological Society.
- Description: 2003008129
- Authors: Coffey, V. G. , Pilegaard, H. , Garnham, A. P. , O'Brien, Brendan , Hawley, J. A.
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Applied Physiology Vol. 106, no. 4 (2009), p. 1187-1197
- Full Text:
- Reviewed:
- Description: We examined acute molecular responses in skeletal muscle to divergent exercise stimuli by combining consecutive bouts of resistance and endurance exercise. Eight men [22.9 ± 6.3 yr, body mass of 73.2 ± 4.5 kg, peak O2 uptake (V̇O2peak) of 54.0 ± 5.7 ml·kg-1·min-1] were randomly assigned to complete trials consisting of either resistance exercise (8 x 5 leg extension, 80% 1 repetition maximum) followed by a bout of endurance exercise (30 min cycling, 70% V̇O2peak) or vice versa. Muscle biopsies were obtained from the vastus lateralis at rest, 15 min after each exercise bout, and after 3 h of passive recovery to determine early signaling and mRNA responses. Phosphorylation of Akt and Akt1Ser473 were elevated 15 min after resistance exercise compared with cycling, with the greatest increase observed when resistance exercise followed cycling (∼55%; P < 0.01). TSC2-mTOR-S6 kinase phosphorylation 15 min after each bout of exercise was similar regardless of the exercise mode. The cumulative effect of combined exercise resulted in disparate mRNA responses. IGF-I mRNA content was reduced when cycling preceded resistance exercise (-42%), whereas muscle ring finger mRNA was elevated when cycling was undertaken after resistance exercise (∼52%; P < 0.05). The hexokinase II mRNA level was higher after resistance cycling (∼45%; P < 0.05) than after cycling-resistance exercise, whereas modest increases in peroxisome proliferator-activated receptor gamma coactivator-1α mRNA did not reveal an order effect. We conclude that acute responses to diverse bouts of contractile activity are modified by the exercise order. Moreover, undertaking divergent exercise in close proximity influences the acute molecular profile and likely exacerbates acute "interference." Copyright © 2009 the American Physiological Society.
- Description: 2003008129
Supplementing regular training with short-duration sprint-agility training leads to a substantial increase in repeated sprint-agility performance with national level badminton players
- O'Brien, Brendan, Walklate, Benjamin, Young, Warren, Paton, Carl
- Authors: O'Brien, Brendan , Walklate, Benjamin , Young, Warren , Paton, Carl
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 23, no. 5 (2009), p. 1477–1481
- Full Text:
- Reviewed:
- Description: Walklate, BM, O’Brien, BJ, Paton, CD, and Young, W. Supplementing regular training with short-duration sprint-agility training leads to a substantial increase in repeated sprint-agility performance with national level badminton players. J Strength Cond Res. 23(5): 1477–1481, 2009—Repeated-agility sprint ability is an important performance characteristic of badminton players. However, it is unclear whether regular badminton training is sufficient to improve repeated-agility sprint ability or whether supplementary training is required. Therefore, our aim was to investigate whether supplementing regular group training with short sessions of badminton-specific agility-sprint training conferred any greater changes in performance than regular training alone. Twelve national level badminton players completed a set of performance tests in the week before and after a 4-week training period. Performance tests consisted of 10- and 20- meter sprints, a multistage fitness test, a 300-meter shuttle run, and a novel badminton sprint protocol. After pretesting, pairmatched participants were randomly assigned into regular or supplementary training groups. Both groups undertook regular national squad training consisting of 4 2-hour sessions per week. In addition, the supplementary group completed a highintensity sprint-training regime consisting of 7 to 15 repeats of badminton-specific sprints twice per week. Relative to control, the supplementary training group reported improvements (mean 6 90% confidence limits) in the 300-meter shuttle run (2.4% 6 2.7%) and badminton sprint protocol (3.6% 6 2.6%). However, there were no substantial difference in either the 10- meter (20.3% 6 2.1%) or 20-meter (20.6% 6 1.8%) sprint or the multistage fitness test (0.0% 6 2.7%). Supplementing regular training with sessions of short-duration sprint training appears to lead to worthwhile increases in repeated-agility sprint performance with national level badminton players.
- Description: 2003008105
- Authors: O'Brien, Brendan , Walklate, Benjamin , Young, Warren , Paton, Carl
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 23, no. 5 (2009), p. 1477–1481
- Full Text:
- Reviewed:
- Description: Walklate, BM, O’Brien, BJ, Paton, CD, and Young, W. Supplementing regular training with short-duration sprint-agility training leads to a substantial increase in repeated sprint-agility performance with national level badminton players. J Strength Cond Res. 23(5): 1477–1481, 2009—Repeated-agility sprint ability is an important performance characteristic of badminton players. However, it is unclear whether regular badminton training is sufficient to improve repeated-agility sprint ability or whether supplementary training is required. Therefore, our aim was to investigate whether supplementing regular group training with short sessions of badminton-specific agility-sprint training conferred any greater changes in performance than regular training alone. Twelve national level badminton players completed a set of performance tests in the week before and after a 4-week training period. Performance tests consisted of 10- and 20- meter sprints, a multistage fitness test, a 300-meter shuttle run, and a novel badminton sprint protocol. After pretesting, pairmatched participants were randomly assigned into regular or supplementary training groups. Both groups undertook regular national squad training consisting of 4 2-hour sessions per week. In addition, the supplementary group completed a highintensity sprint-training regime consisting of 7 to 15 repeats of badminton-specific sprints twice per week. Relative to control, the supplementary training group reported improvements (mean 6 90% confidence limits) in the 300-meter shuttle run (2.4% 6 2.7%) and badminton sprint protocol (3.6% 6 2.6%). However, there were no substantial difference in either the 10- meter (20.3% 6 2.1%) or 20-meter (20.6% 6 1.8%) sprint or the multistage fitness test (0.0% 6 2.7%). Supplementing regular training with sessions of short-duration sprint training appears to lead to worthwhile increases in repeated-agility sprint performance with national level badminton players.
- Description: 2003008105
The effects of increased absolute training intensity on adaptations to endurance exercise training
- McNicol, Ashleigh, O'Brien, Brendan, Paton, Carl, Knez, Wade
- Authors: McNicol, Ashleigh , O'Brien, Brendan , Paton, Carl , Knez, Wade
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 12, no. 4 (2009), p. 485-489
- Full Text:
- Reviewed:
- Description: "Progressive overload" is regarded an important principle to consider in maximising endurance training adaptations, yet little scientific evidence supports this concept. The aim of the present study was to compare differences in endurance performance after a training regime where treadmill-running intensity was incrementally elevated to a regime where running intensity remained unchanged. Twenty-eight healthy untrained males and females were randomly and equally assigned into both regimes. All participants performed 20 min treadmill-running sessions 3 times a week for 6 weeks. Prior to and after training, maximum oxygen uptake (over(V, ̇) O2max), oxygen uptake and velocity at the lactate threshold (LTVO2 and LTv) and maximum treadmill velocity (Vmax) were measured in an incremental treadmill test. 5000 m time trial performance was also assessed. In the incremental intensity regime treadmill velocity commenced at 0.8 km·h-1 below the LTv and was increased by 0.1 km·h-1 every session. In the constant intensity regime treadmill speed was kept constant at 0.8 km·h-1 below the LTv for the duration of the training. The study revealed that both regimens increased over(V, ̇) O2max, Vmax LTVO2, LTv and decreased 5000 m time trial significantly after training. There were no significant differences in the changes between regimens for over(V, ̇) O2max, Vmax and 5000 m time trial. However, the increase in LTVO2 and LTv were significantly greater in the incremental intensity regime compared to the constant intensity regime. The present data show that 20 min treadmill-running sessions performed 3 times a week for 6 weeks improves endurance performance and that progressively elevating exercise intensity is important to maximise improvements in LTVO2 and LTv. © 2008 Sports Medicine Australia.
- Description: 2003008109
- Authors: McNicol, Ashleigh , O'Brien, Brendan , Paton, Carl , Knez, Wade
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 12, no. 4 (2009), p. 485-489
- Full Text:
- Reviewed:
- Description: "Progressive overload" is regarded an important principle to consider in maximising endurance training adaptations, yet little scientific evidence supports this concept. The aim of the present study was to compare differences in endurance performance after a training regime where treadmill-running intensity was incrementally elevated to a regime where running intensity remained unchanged. Twenty-eight healthy untrained males and females were randomly and equally assigned into both regimes. All participants performed 20 min treadmill-running sessions 3 times a week for 6 weeks. Prior to and after training, maximum oxygen uptake (over(V, ̇) O2max), oxygen uptake and velocity at the lactate threshold (LTVO2 and LTv) and maximum treadmill velocity (Vmax) were measured in an incremental treadmill test. 5000 m time trial performance was also assessed. In the incremental intensity regime treadmill velocity commenced at 0.8 km·h-1 below the LTv and was increased by 0.1 km·h-1 every session. In the constant intensity regime treadmill speed was kept constant at 0.8 km·h-1 below the LTv for the duration of the training. The study revealed that both regimens increased over(V, ̇) O2max, Vmax LTVO2, LTv and decreased 5000 m time trial significantly after training. There were no significant differences in the changes between regimens for over(V, ̇) O2max, Vmax and 5000 m time trial. However, the increase in LTVO2 and LTv were significantly greater in the incremental intensity regime compared to the constant intensity regime. The present data show that 20 min treadmill-running sessions performed 3 times a week for 6 weeks improves endurance performance and that progressively elevating exercise intensity is important to maximise improvements in LTVO2 and LTv. © 2008 Sports Medicine Australia.
- Description: 2003008109
Treadmill velocity best predicts 5000-m run performance
- Stratton, E., O'Brien, Brendan, Harvey, Jack, Blitvich, Jennifer, McNicol, Ashleigh, Janissen, D., Paton, Carl, Knez, Wade
- Authors: Stratton, E. , O'Brien, Brendan , Harvey, Jack , Blitvich, Jennifer , McNicol, Ashleigh , Janissen, D. , Paton, Carl , Knez, Wade
- Date: 2009
- Type: Text , Journal article
- Relation: International Journal of Sports Medicine Vol. 30, no. 1 (2009), p. 40-45
- Full Text:
- Reviewed:
- Description: In this study, we aimed to investigate physiological determinants of endurance performance that best predict 5000-m average run velocity before and after endurance training. Thirty-nine previously untrained participants completed a 5000-m run; a constant velocity test (measuring running economy); and an incremental treadmill test to determine maximal oxygen uptake, final treadmill velocity, and velocity and oxygen uptake at lactate threshold, before and after six weeks of endurance training. Maximal oxygen uptake, final treadmill velocity, and velocity and oxygen uptake at threshold all increased significantly after training (p < 0.05). Average velocity for 5000m increased significantly (p < 0.05). Running economy was not significantly altered. Correlation analysis revealed final treadmill velocity was most strongly related to 5000-m performance, in both untrained and trained states (r = 0.89, 0.83). Lactate threshold velocity (r = 0.73, 0.76), maximal oxygen uptake (r = 0.55, 0.51) and oxygen uptake at threshold (r = 0.45, 0.45) also showed significant correlations. In contrast, running economy was not significantly related to performance. These results demonstrate that final treadmill velocity in an V̇O2max test is the single best predictor of 5000-m performance in untrained and trained states. Furthermore, stepwise regression analysis showed that only velocity at lactate threshold significantly improved the accuracy of prediction provided by final treadmill velocity alone. © Georg Thieme Verlag KG Stuttgart.
- Description: 2003008110
Caffeine has a small effect on 5-km running performance of well-trained and recreational runners
- O'Rourke, Matthew, O'Brien, Brendan, Knez, Wade, Paton, Carl
- Authors: O'Rourke, Matthew , O'Brien, Brendan , Knez, Wade , Paton, Carl
- Date: 2008
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 11, no. 2 (2008), p. 231-233
- Full Text:
- Reviewed:
- Description: The purpose of this study was to investigate if caffeine ingestion improves 5-km time-trial performance in well-trained and recreational runners. Using a double-blind placebo-controlled design, 15 well-trained and 15 recreational runners completed two randomized 5-km time-trials, after ingestion of either 5 mg kg-1 of caffeine or a placebo. Caffeine ingestion significantly improved 5-km running performance in both the well-trained and recreational runners. In comparison to the placebo trial, the caffeine trial resulted in 1.1% (90% CI 0.4-1.6) and 1.0% (0.2-2%) faster times for the well-trained and recreational runners. Reliability testing of the recreational runners indicated a test-retest error of measurement of 1.4%. We conclude that caffeine ingestion is likely to produce small but significant gains in 5-km running performance for both well-trained and recreational runners. © 2007 Sports Medicine Australia.
- Description: C1
- Authors: O'Rourke, Matthew , O'Brien, Brendan , Knez, Wade , Paton, Carl
- Date: 2008
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 11, no. 2 (2008), p. 231-233
- Full Text:
- Reviewed:
- Description: The purpose of this study was to investigate if caffeine ingestion improves 5-km time-trial performance in well-trained and recreational runners. Using a double-blind placebo-controlled design, 15 well-trained and 15 recreational runners completed two randomized 5-km time-trials, after ingestion of either 5 mg kg-1 of caffeine or a placebo. Caffeine ingestion significantly improved 5-km running performance in both the well-trained and recreational runners. In comparison to the placebo trial, the caffeine trial resulted in 1.1% (90% CI 0.4-1.6) and 1.0% (0.2-2%) faster times for the well-trained and recreational runners. Reliability testing of the recreational runners indicated a test-retest error of measurement of 1.4%. We conclude that caffeine ingestion is likely to produce small but significant gains in 5-km running performance for both well-trained and recreational runners. © 2007 Sports Medicine Australia.
- Description: C1
The effects of interval-exercise duration and intensity on oxygen consumption during treadmill running
- O'Brien, Brendan, Wibskov, Jim, Knez, Wade, Paton, Carl, Harvey, Jack
- Authors: O'Brien, Brendan , Wibskov, Jim , Knez, Wade , Paton, Carl , Harvey, Jack
- Date: 2008
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 11, no. 3 (2008), p. 287-290
- Full Text:
- Reviewed:
- Description: The magnitude of improvement in peak oxygen uptake (over(V, ̇)
- Description: C1
- Authors: O'Brien, Brendan , Wibskov, Jim , Knez, Wade , Paton, Carl , Harvey, Jack
- Date: 2008
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 11, no. 3 (2008), p. 287-290
- Full Text:
- Reviewed:
- Description: The magnitude of improvement in peak oxygen uptake (over(V, ̇)
- Description: C1