Sport and leisure activities in the heat: What safety resources exist?
- Authors: Gonsalves, Marlon , O'Brien, Brendan , Twomey, Dara
- Date: 2021
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 24, no. 8 (2021), p. 781-786
- Full Text: false
- Reviewed:
- Description: Objectives: To conduct a document analysis of sports and leisure activity heat-related injury prevention resources in Australia and develop an understanding of the content within those resources. Design & Methods: Heat resources were included if they dealt specifically with, or could be extrapolated to, prevention of heat-related injuries. Collating strategies for the catalogue included: (1) a detailed search of the organisation's website and (2) an online search for sport specific heat resources. A content analysis of each resource was first performed, and descriptive codes were assigned to the data using qualitative data analysis software. Every coded text was recorded as an individual data point (n). Common sub-categories were identified by thematic analysis and collated under three broader categories. Results: A total of 468 data points were identified within the 64 heat resources found. Guidelines (n = 20) and policies (n = 18) were the most common type of resources followed by factsheets (n = 9), webpages (n = 8), laws and by-laws (n = 2). Three overarching categories emerged through the data analysis process: preventive strategies (n = 299, 63.9%), risk factors (n = 94, 20.1%), treatment (n = 75, 16.0%). Activity modification, which included information on rescheduling games and extra breaks, was the most common intervention. Cricket, soccer, swimming and triathlon had the most complete set of heat resources. Conclusions: The findings of this study provide an insight into the composition of heat-related sports injury prevention resources within Australia and identify areas for development. As the resources were incomplete for many sports, the development of more comprehensive heat safety resources is required to ensure the safety of participants. © 2021 Elsevier Ltd
Relationship between selected physical qualities, bowling kinematics, and pace bowling skill in club-standard cricketers
- Authors: Feros, Simon , Young, Warren , O'Brien, Brendan
- Date: 2019
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 33, no. 10 (Oct 2019), p. 2812-2825
- Full Text: false
- Reviewed:
- Description: Although strength and conditioning of cricket pace bowlers has become more specialized in recent times, little is understood about the interplay between physical capacities, pace bowling kinematics, and pace bowling skill measures. This study sought to determine these interrelationships. Thirty-one male club-standard pace bowlers completed 3 test sessions on separate occasions 4-7 days apart. The first testing session comprised an 8-over pace bowling assessment, where bowling skill and selected bowling kinematics were measured. A physical test battery was completed over the remaining 2 sessions. Peak and mean ball release (BR) speed were related with 1 repetition maximum pull-up strength (r(s) = 0.56, p = 0.005) and correlated with 20-m sprint time (r(s) = -0.42, p = 0.022; r(s) = -0.37, p = 0.044, respectively). Mean radial error was associated with 10-m and 20-m sprint times (r(s) = 0.41, p = 0.030; r(s) = 0.38, p = 0.037, respectively), and correlated with height and peak power from 3 countermovement jumps (CMJs) (r(s) = -0.39, p = 0.036; r(s) = -0.41, p = 0.031, respectively), and mean peak power from 20 CMJs (r(s) = -0.45, p = 0.020). Bivariate variable error was correlated with front-leg extension angle at BR (r(s) = 0.41, p = 0.036), and also with approach speed (r(s) = -0.36, p = 0.050). These relationships may assist strength and conditioning coaches in designing more effective training programs to enhance bowling speed and accuracy. Training interventions are warranted, however, to validate these associations.
Telomeres, exercise and cardiovascular disease : Finding the means to justify the ends
- Authors: Chilton, Warrick , O'Brien, Brendan , Grace, Fergal , Charchar, Fadi
- Date: 2017
- Type: Text , Journal article
- Relation: Acta Physiologica Vol. 220, no. 2 (2017), p. 186-188
- Full Text: false
- Reviewed:
Epigenetic changes in leukocytes after 8 weeks of resistance exercise training
- Authors: Denham, Joshua , Marques, Francine , Bruns, Emma , O'Brien, Brendan , Charchar, Fadi
- Date: 2016
- Type: Text , Journal article
- Relation: European Journal of Applied Physiology Vol. 116, no. 6 (2016), p. 1245-1253
- Relation: http://purl.org/au-research/grants/nhmrc/1009490
- Full Text: false
- Reviewed:
- Description: PURPOSE: Regular engagement in resistance exercise training elicits many health benefits including improvement to muscular strength, hypertrophy and insulin sensitivity, though the underpinning molecular mechanisms are poorly understood. The purpose of this study was to determine the influence 8 weeks of resistance exercise training has on leukocyte genome-wide DNA methylation and gene expression in healthy young men. METHODS: Eight young (21.1 +/- 2.2 years) men completed one repetition maximum (1RM) testing before completing 8 weeks of supervised, thrice-weekly resistance exercise training comprising three sets of 8-12 repetitions with a load equivalent to 80 % of 1RM. Blood samples were collected at rest before and after the 8-week training intervention. Genome-wide DNA methylation and gene expression were assessed on isolated leukocyte DNA and RNA using the 450K BeadChip and HumanHT-12 v4 Expression BeadChip (Illumina), respectively. RESULTS: Resistance exercise training significantly improved upper and lower body strength concurrently with diverse genome-wide DNA methylation and gene expression changes (p = 0. 01). DNA methylation changes occurred at multiple regions throughout the genome in context with genes and CpG islands, and in genes relating to axon guidance, diabetes and immune pathways. There were multiple genes with increased expression that were enriched for RNA processing and developmental proteins. Growth factor genes-GHRH and FGF1-showed differential methylation and mRNA expression changes after resistance training. CONCLUSIONS: Our findings indicate that resistance exercise training improves muscular strength and is associated with reprogramming of the leukocyte DNA methylome and transcriptome.
Telomere length maintenance and cardio-metabolic disease prevention through exercise training
- 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
- 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
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- 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.
Accelerometer load as a measure of activity profile in different standards of netball match play
- Authors: Cormack, Stuart , Smith, Renee , Mooney, Mitchell , Young, Warren , O'Brien, Brendan
- Date: 2014
- Type: Text , Journal article
- Relation: International Journal of Sports Physiology and Performance Vol. 9, no. 2 (2014), p. 283-291
- Full Text: false
- Reviewed:
- Description: To determine differences in load/min (AU) between standards of netball match play., Methods: Load/ min (AU) representing accumulated accelerations measured by triaxial accelerometers was recorded during matches of 2 higher- and 2 lower-standard teams (N = 32 players). Differences in load/min (AU) were compared within and between standards for playing position and periods of play. Differences were considered meaningful if there was >75% likelihood of exceeding a small (0.2) effect size., Results: Mean (± SD) full-match load/min (AU) for the higher and lower standards were 9.96 ± 2.50 and 6.88 ± 1.88, respectively (100% likely lower). The higher standard had greater (mean 97% likely) load/min (AU) values in each position. The difference between 1st and 2nd halves' load/min (AU) was unclear at the higher standard, while lower-grade centers had a lower (-7.7% ± 10.8%, 81% likely) load/min (AU) in the 2nd half and in all quarters compared with the 1st. There was little intrastandard variation in individual vector contributions to load/min (AU); however, higher-standard players accumulated a greater proportion of the total in the vertical plane (mean 93% likely)., Conclusions: Higher-standard players produced greater load/min (AU) than their lower-standard counterparts in all positions. Playing standard influenced the pattern of load/min (AU) accumulation across a match, and individual vector analysis suggests that different-standard players have dissimilar movement characteristics. Load/min (AU) appears to be a useful method for assessing activity profile in netball. © 2014 Human Kinetics, Inc.
Assessment of decision-making performance and in-game physical exertion of Australian football umpires
- Authors: Larkin, Paul , O'Brien, Brendan , Mesagno, Christopher , Berry, Jason , Harvey, Jack , Spittle, Michael
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of Sports Sciences Vol. 32, no. 15 (2014), p. 1446-1453
- Full Text: false
- Reviewed:
- Description: The aim of this study is to investigate the effects of in-game physical exertion on decision-making performance of Australian football umpires. Fifteen Australian football umpires (Mage = 36, s = 13.5 years; Mgames umpired = 235.2, s = 151.3) volunteered to participate in the study. During five competitive Australian football pre-season games, measures of in-game physical exertion (blood lactate levels, global positioning system [GPS]) and decision-making performance (video-based test) were obtained. There were no significant correlations between physical exertion in a particular quarter and decision-making performance in either the same quarter or any other quarter. Video-based decision-making performance was effected by time in game χ2(3) = 24.24, P = 0.001, with Quarter 4 performance significantly better than both Quarter 2 and Quarter 3. In-game physical exertion (blood lactate) significantly decreased over the course of the game χ2(3) = 11.58, P = 0.009. Results indicate no definable link between in-game physical exertion and decision-making performance. It is, however, presumed that decision-making performance may be affected by the time or context of the game. Future research is warranted to explore the relationship between physical exertion and decision-making performance to potentially inform Australian football umpire training programmes that replicate in-game physical and decision-making demands.
Exercise : Putting action into our epigenome
- 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
Do physical capacity and interchange rest periods influence match exercise-intensity profile in Australian football?
- 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
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- 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
- 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: false
- Reviewed:
- Description: 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 (Deltar > 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.
The acute effects of heavy-ball bowling on fast bowling performance in cricket
- Authors: Feros, Simon , Young, Warren , O'Brien, Brendan
- Date: 2013
- Type: Text , Journal article
- Relation: Journal of Australian Strength and Conditioning Vol. 21, no. S2 (2013), p. 41-44
- Full Text: false
- Reviewed:
- Description: Poster presented at conferrence
Reliability and validity of a novel intermittent peak running speed test for Australian football
- Authors: Mooney, Mitchell , Hunter, Jayden , O'Brien, Brendan , Berry, Jason , Young, Warren
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 25, no. 4 (2011), p. 973-979
- Full Text: false
- Reviewed:
- Description: Mooney, MG, Hunter, JR, O'Brien, BJ, Berry, JT, and Young, WB. Reliability and validity of a novel intermittent peak running speed test for Australian football. J Strength Cond Res. 25(4): 973-979, 2011-Australian football requires frequent intermittent sprinting close to peak running speed. However, tests assessing the capability to maintain intermittent peak running speed are not reported in scientific literature. Therefore, our objective is to report the reliability and validity of a novel intermittent peak running speed test. The intermittent peak running speed test required footballers to perform 10 repetitions on 25-second intervals. Each repetition required 15-m jogging, 20-m acceleration to peak speed, 10 m to sustain peak speed, 20-m deceleration, and finally a 15-m jog. Intermittent peak running speed was determined by portable global positioning system. To assess reliability, 26 footballers performed the intermittent peak running speed test on 2 occasions 3-5 days apart. Our results revealed that average peak speed had a coefficient of variation of 2.2% and an intraclass correlation of 0.91. To assess construct validity, average peak speed was compared between elite, sub-elite, and regional footballers. The average peak speed of the elite footballers (28.6 ± 1.7 km-h-1) was higher than that of the sub-elite (27.4 6 1.7 km-h -1) and regional (27 6 1.9 km-h-1) competitors (p < 0.05). Our study revealed that the intermittent peak running speed test possesses acceptable reliability and distinguishes between elite and sub-elite footballers. © 2011 National Strength and Conditioning Association.
Repeated sprint training improves intermittent peak running speed in team-sport athletes
- Authors: Hunter, Jayden , O'Brien, Brendan , Mooney, Mitchell , Berry, Jason , Young, Warren , Down, Neville
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 25, no. 5 (2011), p. 1318-1325
- Full Text: false
- Reviewed:
- Description: Repeated sprint training improves intermittent peak running speed in team-sport athletes. J Strength Cond Res 25(5): 1318-1325, 2011-The aim of this study was to compare the effect of 2 repeated sprint training interventions on an intermittent peak running speed (IPRS) test designed for Australian Rules football. The test required participants to perform 10 3 10-m maximal efforts on an 80-m course every 25 seconds, for each of which the mean peak speed (kilometers per hour) was recorded to determine IPRS. The training interventions were performed twice weekly for 4 weeks immediately before regular football training. In the constant volume intervention (CVol), sprint repetition number remained at 10 (n = 9), and in the linear increase in volume (LIVol) intervention, repetition number increased linearly each week by 2 repetitions (n = 12). Intermittent peak running speed, 300-m shuttle test performance, and peak running speed were assessed before and upon completion of training. All measures were compared to a control group (CON; n = 8) in which players completed regular football training exclusively. Intermittent peak running speed performance in CVol and LIVol improved significantly (p < 0.01) by 5.2 and 3.8%, respectively, with no change in IPRS for CON. There were no differences in IPRS changes between CVol and LIVol. Additionally, peak running speed improved significantly (p < 0.01) by 5.1% for CVol, whereas 300-m shuttle performance improved significantly (p < 0.01) by 2.6% for LIVol only. Intermittent peak running speed, 300-m shuttle performance and peak running speed were improved after 4 weeks of training; however, progressively increasing sprint repetition number had no greater advantage on IPRS adaptation. Additionally, exclusive regular football training over a 4-week period is unlikely to improve IPRS, peak running speed, or 300-m shuttle performance.
Caffeine has a small effect on 5-km running performance of well-trained and recreational runners
- 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
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- 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
- 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
Six minute walk distance is greater when performed in a group than alone
- Authors: Grindrod, D. , Paton, Carl , Knez, Wade , O'Brien, Brendan
- Date: 2006
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 40, no. 10 (Oct 2006), p. 876-877
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- Description: Objective: To investigate whether the distance covered in the six minute walk test was affected by walking with a group of others in comparison with performing the test alone. Methods: Eight healthy men ( mean (SD) age 21.0 (0.9) years) and eight healthy women ( mean ( SD) age 20.8 (2.0) years) performed in random order two six minute walk tests either alone or in a group of four on two separate occasions one week apart. Results: Distance covered increased significantly from a mean of 653 ( 61) m in the individual male tests to 735 (79) m in the male group tests ( p< 0.05), and 616 ( 75) m in the individual female tests to 701 ( 54) m in the female group tests ( p< 0.01). The men increased the distance walked in six minutes by 12.5% and the women by 13.7% when they performed the test as a group. Conclusion: Performing the six minute walk test in a group facilitates its execution.
- Description: C1
- Description: 2003002117
The effect of 4 weeks fasting during Ramadan upon isokinetic knee flexor/extensor performance
- Authors: Grantham, Justin , Belhaj, Jilal , O'Brien, Brendan , Balasekaran, Govindasamy
- Date: 2006
- Type: Text , Journal article
- Relation: Medicine & Science in Sports & Exercise Vol. 38, no. 5 (2006), p. S337
- Full Text: false
- Reviewed:
- Description: 2003003746
Immediate re-hydration post-exercise is not coincident with raised mean arterial pressure over a 30-minute observation period
- Authors: Kay, Bartholomew , O'Brien, Brendan , Gill, Nicholas
- Date: 2005
- Type: Text , Journal article
- Relation: Journal of Sports Science and Medicine Vol. 4, no. 4 (Dec 2005), p. 422-429
- Full Text:
- Reviewed:
- Description: This investigation assessed the effects of immediate or delayed re-hydration post-exercise, on mean arterial blood pressure ( MAP) and on blood plasma volume (PV) expansion post-exercise. It was hypothesised that fluid ingestion would raise MAP and attenuate PV expansion. On two occasions separated by seven days, eight males ( age 20.4 +/- 1.7 years, mass 79 +/- 5 kg [ means +/- SD]; VO2 max 48 +/- 11 mL center dot kg(-1) center dot minute(-1), [mean +/- SE]) cycled in the heat (35 degrees C, 50% relative humidity) at a power output associated with 50% VO2 max, until 1.0kg body mass was lost. 1L water was given either immediately thereafter, or two hours post-exercise by random assignment. On both occasions, MAP was calculated every five minutes for a period of 30-minutes post-exercise, and change in PV was calculated 24-hours post-exercise. Repeated measures ANOVA for MAP results suggested a low probability of a treatment effect ( p = 0.655), a high probability of a time effect ( p = 0.006), and a moderately high probability of a time x treatment interaction ( p = 0.076); MAP tended to be lower when fluid had been consumed. PV expansions 24-hours post-exercise were not significant changes with respect to zero, and were not significantly different by treatment condition. In conclusion: ( a) The exercise was not sufficient to elicit significant PV expansions; thus, we were unable to determine the effects of the timing of post-exercise re-hydration on PV expansion. (b) The hypothesis regarding MAP in response to drinking was not supported, rather there was a 92% probability that the inverse affect occurs.
- Description: C1
- Description: 2003002930
Plasma volume expansion 24-hours post-exercise: Effect of doubling the volume of replacement fluid
- Authors: Kay, Bartholomew , O'Brien, Brendan , Gill, Nicholas
- Date: 2005
- Type: Text , Journal article
- Relation: Journal of Sports Science and Medicine Vol. 4, no. 2 (2005), p. 179-184
- Full Text:
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- Description: The effects of two volumes (1.5 L or 3.0 L) of commercially available electrolyte beverage (1.44 mM·L-1 Na+) taken during a 24-hour recovery period post-exercise, on plasma volume (PV) expansion 24-hours post-exercise were assessed. A simple random-order crossover research design was used. Subjects (n = 9 males: age 21 ± 4 years, body mass 80.0 ± 9.0 kg, peak incremental 60-second cycling power output 297 ± 45 W [means ± SD]) completed an identical exercise protocol conducted in hot ambient conditions (35°C, 50% relative humidity) on two occasions; separated by 7-days. On each occasion, subjects received a different volume of 24-hour fluid intake (commercial beverage) in random order. In each case, the fluid was taken in five equal aliquots over 24-hours. PV expansions 24-hours post-exercise were estimated from changes in haemoglobin and haematocrit. Dependent t-testing revealed no significant differences in PV expansions between trials, however a significant expansion with respect to zero was identified in the 3.0 L trial only. Specifically, PV expansions (%) were; 1.5 L trial: (mean ± SE) 2.3 ± 2.0 (not significant with respect to zero), 3.0 L trial: 5.0 ± 2.0 (p < 0.05, with respect to zero). Under the conditions imposed in the current study, ingesting the greater volume of the beverage lead to larger mean PV expansion.
- Description: C1
- Description: 2003001182