The obesity paradox – some methodological considerations and potential physiological mechanisms
- Authors: Grace, Fergal , Buchan, Duncan , Kilgore, Lon , Baker, Julien
- Date: 2013
- Type: Text , Journal article
- Relation: Journal of Sports Medicine and Doping Studies Vol. 3, no. 1 (2013), p. e133
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Sprint interval training (SIT) is an effective method to maintain cardiorespiratory fitness (CRF) and glucose homeostasis in Scottish adolescents
- Authors: Martin, Rhona , Buchan, Duncan , Baker, John , Young, Julien , Sculthorpe, Nicholas , Grace, Fergal
- Date: 2015
- Type: Text , Journal article
- Relation: Biology of Sport Vol. 32, no. 4 (2015), p. 307-313
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- Description: The present study examined the physiological impact of a school based sprint interval training (SIT) intervention in replacement of standard physical education (SPE) class on cardio-respiratory fitness (CRF) and glucose homeostasis during the semester following summer vacation. Participants (n=49) were randomly allocated to either intervention (SIT; n=26, aged 16.9 +/- 0.3 yrs) or control group who underwent standard physical education (SPE; n=23, aged 16.8 +/- 0.6 yrs). CRF (VO2max) and glucose homeostasis were obtained prior-to and following 7 weeks of SIT exercise. Significant group x time interaction was observed for CRF (P < 0.01) with non-significant trends for fasting insulin (P= 0.08), and HOMA-IR (P=0.06). CRF decreased (P < 0.01) in SPE such that POST intervention CRF was significantly lower (P< 0.05) in SPE. Fasting plasma glucose (P < 0.01), insulin (P< 0.01) and HOMA-IR (P< 0.01) increased significantly amongst SPE. The main finding of the present study is that 7-weeks of SIT exercise is an effective method of maintaining (but not improving) CRF and fasting insulin homeostasis amongst school-going adolescents. SIT exercise demonstrates potential as a time efficient physiological adjunct to standard PE class in order to maintain CRF during the school term.
Utility of the hypertriglyceridemic waist phenotype in the cardiometabolic risk assessment of youth stratified by body mass index
- Authors: Buchan, Duncan , Boddy, Lynne , Despres, Jean , Grace, Fergal , Sculthorpe, Nicholas , Mahoney, Craig , Baker, Julien
- Date: 2016
- Type: Text , Journal article
- Relation: Pediatric Obesity Vol. 11, no. 4 (2016), p. 292-298
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- Description: BACKGROUND: It is unclear whether the hypertriglyceridemic waist phenotype (HTWP) can be used to identify those at most risk of cardiometabolic disorders. OBJECTIVES: The utility of the HTWP as a useful predictor of cardiometabolic risk in youth stratified by body mass index was assessed. METHODS: Three hundred and eighty-seven children (12-17.5 years) were used within this cross-sectional study. Participants were classified as normal weight or overweight/obese according to the International Obesity Task Force criteria. The HTWP phenotype was defined as having a waist circumference >/=90th percentile for age and gender with concomitant triglyceride concentrations >/=1.24 mmol L(-1) . Cardiometabolic risk profiles were compared using MANCOVA. RESULTS: Normal weight participants with the HTWP had significantly higher levels of C-reactive protein 2.6 +/- 0.4 vs. 1.6 +/- 0.3 mg L(-1) (P < 0.05) and cardiometabolic risk scores (1.3 +/- 0.3 vs. -0.7 +/- 0.2 and 2.1 +/- 0.4 vs. -0.5 +/- 0.2; both P < 0.05) compared with those of a normal weight without the HTWP. Overweight/obese participants with the HTWP had significantly higher C-reactive protein levels (3.5 +/- 0.6 vs. 2.6 +/- 0.5; P < 0.05) as well as both cardiometabolic risk scores (1.6 +/- 0.6 vs. 0.9 +/- 0.2 and 2.2 +/- 0.6 vs. 0.8 +/- 0.2; both P < 0.001) when compared with overweight/obese participants without the HTWP. CONCLUSIONS: The HTWP may serve as a simple and clinically useful approach to identify youth at increased cardiometabolic risk.
Utility of three anthropometric indices in assessing the cardiometabolic risk profile in children
- Authors: Buchan, Duncan , Boddy, Lynne , Grace, Fergal , Brown, Elise , Sculthorpe, Nicholas , Cunningham, Conor , Murphy, Marie , Dagger, Rebecca , Foweather, Lawrence , Graves, Lee , Hopkins, Nicola , Stratton, Gareth , Baker, Julien
- Date: 2016
- Type: Text , Journal article
- Relation: American Journal of Human Biology Vol. , no. (2016), p. 1-10
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- Description: OBJECTIVES: To evaluate the ability of BMI, WC, and WHtR to identify increased cardiometabolic risk in pre-adolescents. METHODS: This is a cross-sectional study involving 192 children (10.92 +/- 0.58 years, 56% female) from the United Kingdom between 2010 and 2013. Receiver operating characteristic curves determined the discriminatory ability of BMI, WC and WHtR to identify individuals with increased cardiometabolic risk (increased clustered triglycerides, HDL-cholesterol, systolic blood pressure, cardiorespiratory fitness, and glucose). RESULTS: A WHtR >/= 0.5 increased the odds by 5.2 (95% confidence interval 2.6 - 10.3) of having increased cardiometabolic risk. Similar associations were observed for BMI and WC. Both BMI-z and WHtR were fair predictors of increased cardiometabolic risk, although BMI-z demonstrated the best trade-off between sensitivity and specificity, 76.1% and 63.6%, compared with 68.1% and 65.5% for WHtR. Cross-validation analysis revealed that BMI-z and WHtR correctly classified 84% of individuals (kappa score = 0.671, 95% CI 0.55, 0.79). The sensitivity of the cut-points suggests that 89.3% of individuals were correctly classified as being at risk with only 10.7% misdiagnosed whereas the specificity of the cut-points indicated that 77.8% of individuals were correctly identified as being healthy with 22.2% of individuals incorrectly diagnosed as being at risk. CONCLUSIONS: Findings suggest that WHtR provides similar cardiometabolic risk estimates to age and sex adjusted BMI.
Sprint interval training and the school curriculum : Benefits upon cardiorespiratory fitness, physical activity profiles, and cardiometabolic risk profiles of healthy adolescents
- Authors: Martin-Smith, Rhona , Buchan, Duncan , Baker, Julien , Macdonald, Mhairi , Sculthorpe, Nicholas , Easton, Chris , Knox, Allan , Grace, Fergal
- Date: 2019
- Type: Text , Journal article
- Relation: Pediatric Exercise Science Vol. 31, no. 3 (2019), p. 296-305
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- Description: Background: This study examined the impact of a 4-week school-based sprint interval training program on cardiorespiratory fitness (CRF), daily physical activity (PA) behavior, and cardiometabolic risk (CMR) outcomes in adolescents. Methods: A total of 56 adolescents (22 females) were allocated to either an intervention (n = 22; 17.0 [0.3] y) or control group (n = 30; 16.8 [0.5] y). Intervention group performed 5 to 6, 30 second "all out" running sprints, interspersed with 30-second rest intervals, 3 times per week, for 4 consecutive weeks, whereas control group performed their normal physical education lessons. CRF was estimated from the 20-m multistage fitness test and PA behavior was determined using accelerometry. Fasting blood samples were obtained to measure biochemical markers of CMR. Results: Significant group x time interactions were observed for CRF (5.03 [1.66 to 8.40]; P < .001; d = 0.95), sedentary time (136.15 [91.91 to 180.39]; P = .004; d = 1.8), moderate PA (57.20 [32.17 to 82.23]; P < .001; d = 1.5), vigorous PA (5.40 [4.22 to 6.57]; P < .001; d = 1.2), fasting insulin (0.37 [-0.48 to 1.21]; P = .01; d = 1.0), homeostasis model of assessment-insulin resistance (0.26 [0.15 to 0.42]; P < .001; d = 0.9), and clustered CMR score (0.22 [-0.05 to 0.68]; P < .001; d = 10.63). Conclusion: Findings of this study indicate that 4 weeks of school-based sprint interval training improves CRF, improves PA profiles, and maintains CMR in adolescents during the school term.
High intensity interval training (HIIT) improves cardiorespiratory fitness (CRF) in healthy, overweight and obese adolescents : a systematic review and meta-analysis of controlled studies
- Authors: Martin-Smith, Rhona , Cox, Ashley , Buchan, Duncan , Baker, Julien , Grace, Fergal , Sculthorpe, Nicholas
- Date: 2020
- Type: Text , Journal article , Review
- Relation: International Journal of Environmental Research and Public Health Vol. 17, no. 8 (2020), p.
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- Description: Background: High Intensity Interval Training (HIIT) is a sustainable and effective method for improving Cardiorespiratory Fitness (CRF) in adolescents. HIIT is proven to produce equal or greater improvements in CRF when compared to moderate intensity continuous exercise (MICE) in adolescents. Methods: The studies included were considered eligible if: (1) Participants were adolescents (11–18 years old); (2) Examined changes in CRF measured either directly or indirectly; (3) Included a non-exercising control group or MICE comparison group; (4) Participants were matched at enrolment; (5) Reported HIIT protocol information; (6) Provided HIIT intensity. A meta-analysis was conducted to determine the effect of HIIT on CRF. Meta-regression and moderator analyses were performed out to quantitatively examine moderators of protocol design on CRF improvements. Results: HIIT displays a moderate effect to improve CRF (g = 0.86, 95% CI 0.518–1.106, p < 0.001). Neither study duration (weeks), nor total or weekly accumulated HIIT volume (min) displayed any significant moderation effect on pooled improvement on CRF (p > 0.05). Conclusions: HIIT is an effective method to improve CRF in adolescents, irrespective of body composition. Notably, meta regression analysis identified that prolonged high volume HIIT programs are similarly effective to short term low volume HIIT programs. This becomes of particular interest for those involved in school curricula, where short HIIT exercise may provide a pragmatic adjunct to the health benefits of Physical Education (PE) lessons. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.