obese men

2010 Asics Conference of Science and Medicine in Sport / Journal of Science and Medicine in Sport 13S (2010) e1–e107

improve knee JPS and single-leg stability. The outcomes did not support the hypothesis that additional balance training using the Wii Fit Plus would improve results in this population. Further investigation is required to determine whether inclusion of the balance program is efficient and effective in treating PFP. doi:10.1016/j.jsams.2010.10.475 15 The relationship between heart period variability and VO2 peak response to high intensity intermittent exercise training S. Boutcher 1,∗ , Y. Park 1 , S. Dunn 2 , Y. Boutcher 1 1 The

University of New South Wales, Australia University, Australia

2 Pepperdine

Introduction: Significant individual differences in the VO2 max response to regular aerobic training have been documented in healthy adults after standardized exercise programs. In prior research the mean improvements in VO2 max have ranged from a 5% decrease to a 40% increase. Recently, baseline autonomic nervous system status has been shown to be a contributor to the training response. High frequency power of heart period variability (HPV), a measure of vagal influence on the heart, has been shown to predict training response independently after adjustment for age, baseline fitness, and BMI. Thus, cardiac vagal modulation of heart rate appears to be an important physiological determinant of training response in healthy subjects. Whether baseline HPV also predicts training response to high intensity intermittent exercise training is undetermined. Thus, the relationship between baseline HPV and the VO2 peak response to 12 weeks of high intensity intermittent exercise training was examined. Methods: Young females (n = 16) exercised three times a week for 12 weeks under supervision. The training consisted of 20 min of intermittent sprinting on a stationary cycle ergometer (8 s sprint, 12 s recovery) each session. Peak oxygen uptake was assessed using open-circuit spirometry (True Max 2400, ParvoMedics). Parasympathetic influence of the heart was assessed through spectral analysis of the inter beat interval. Results: Participants were aged 23 ± 1 years and possessed a BMI of 27.7 ± 0.8 kg m2 and a VO2 peak of 27.3 ± 1.3 ml/kg/min. Baseline heart rate was 67.7 ± 2.6 bpm whereas baseline HPV was 60.3 ± 6.1 (normalised units). The overall increase in VO2 peak after the 12-week training program, despite being anaerobic in nature, was 19.4%. Change in VO2 peak was significantly correlated with initial baseline HPV high frequency in normalized units (r = 0.58; p < 0.05). Conclusions: Cardiac vagal modulation of heart rate appears to make a significant contribution to the aerobic training response after regular high intensity intermittent exercise. Mechanisms underlying this relationship are undetermined but may involve genetic factors. Also the

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cardiovascular system of subjects possessing high vagal influence of the heart may have an enhanced capacity to adapt to exercise training. doi:10.1016/j.jsams.2010.10.476 16 Mechanical work and metabolic stress in response to high- and low-intensity interval exercise among overweight/obese men S. Alkahtani ∗ , A. Hills, N. Byrne, N. King School of Human Movement Studies and the Institute of Health and Biomedical Innovation, Queensland University of Technology, Australia While exercise is recognised as a cornerstone of weight management therapy, there is a growing interest in the use of intermittent exercise. This study aims to compare the effects of mechanically equal acute bouts of low- and high-intensity intermittent exercise on metabolic variables in the obese. Twelve sedentary, overweight/obese males (age 29 years (range 24–38); BMI 29.1 kg/m2 (range 25.5–35); %fat mass 31.7 (range 25.7–35.3)) completed three exercise sessions: an initial graded exercise test to determine maximal fat oxidation rate and maximal aerobic power (FATmax/VO2max ), as well as two matched-work load interval cycling ergometer sessions – low-intensity (FAT-INT) and high-intensity (HIGH-INT) sessions on separate days in random order. The low-intensity interval session involved five-minute repetitions of workloads 20% below and then 20% above the FAT-max intensity (FAT INT). The high-intensity interval session (HIGH INT) consisted of cycling for alternate bouts of 15 s at 85% VO2max and 15 s unloaded recovery. During the sessions and 10 min post-exercise, respiratory gases HR and RPE were measured. A multivariate repeated measures ANOVA was performed, and three explanatory factors that fitted were: intensity, time intervals and variables (VO2 , HR, and RPE). Participants, on average, cycled at 80.7 ± 11.1 W and 48 ± 0.02%VO2 max for 17.5 ± 3.9 min during the HIGH-INT session, and 49.6 ± 12.5 W and 34 ± 0.05%VO2 max for 30 min during the FAT-INT session. The total distance cycled during both exercise bouts, adjusted to HIGH-INT time, demonstrated a high level of agreement. The gross total aerobic and anaerobic energy expenditure was greater during FAT-INT, but the rate was higher during HIGH-INT. VO2 , HR, RER and blood lactate concentration were significantly higher during HIGH-INT, and RPE was insignificantly higher during HIGH-INT. Considering intensity and time, the standardised VO2 and HR curve were comparable during interval exercise. Although the standardised RPE curve apparently differed, no significant differences were observed between RPE and HR as well as VO2 curve. RPE overestimated the metabolic stress observed of HR with significance (p = 0.01) during FAT-INT compared with the gradual incremental test. In conclusion,

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2010 Asics Conference of Science and Medicine in Sport / Journal of Science and Medicine in Sport 13S (2010) e1–e107

obese men can yield equal mechanical work at different interval workloads although they work at higher metabolic stress during HIGH-INT. In addition, RPE overestimates the actual metabolic stress observed of HR during interval exercise among obese men, but no significant differences were found between the RPE and HR curve during interval exercises. doi:10.1016/j.jsams.2010.10.477 17 The dose–response relationship between doephedrine ingestion and exercise performance Pritchard-Peschek 1,∗ ,

K. Slater 3 , D. Taaffe 1

D.

Jenkins 1 ,

M.

2.8 mg kg−1 ; p < 0.001), with the 2.8 mg kg−1 dose eliciting the highest plasma [PSE] both pre-warm up and post-exercise (2.8 mg kg−1 > 2.3 mg kg−1 > PLA; p < 0.001). Conclusion: There was a large individual variation in plasma [PSE] observed among subjects, which may potentially have impacted upon cycling TT performance as there were also large individual variations observed in TT time. It is evident there are external factors influencing PSE’s bioavailability, and these changes in PSE kinetics may be responsible for the observed variation in cycling performance in the present study.

pseu-

Osborne 2 ,

doi:10.1016/j.jsams.2010.10.478 G.

1 The

University of Queensland, Australia Academy of Sport, Australia 3 University of the Sunshine Coast, Australia 2 Queensland

Introduction: Despite the re-addition of pseudoephedrine (PSE) to the World Anti-Doping Agency’s (WADA) Prohibited List, there is evidence to suggest that many athletes will still take the drug (in training and competition) to improve their performance. This is despite uncertainty regarding its efficacy as an ergogenic aid. Performance improvements have been observed with PSE supplementation, however inconsistencies in the dose administered and exercise protocols used make it difficult to interpret its ergogenic effect. The purpose of the present study was to examine a possible dose-response between PSE and endurance exercise performance, whilst tracking changes in biochemical markers that could provide insight on the mechanisms responsible for improvements in performance. Methods: Ten highly trained male cyclists and triathletes (age 26.5 years, range 18–38, mass 75.1 kg, range 65–84, VO2 max 70.6 ml kg min−1 , range 61.7–81.0) underwent three performance trials in which they completed a 20 min variable-intensity warm up, followed by a cycling time trial (TT) in which a fixed amount of work (7 kJ kg−1 body mass (BM)) was completed in the shortest possible time. Sixty minutes before the start of exercise, subjects orally ingested either 2.3 mg kg−1 or 2.8 mg kg−1 BM of PSE or a placebo (PLA) in a randomized, crossover, double-blind manner. Venous blood was sampled at baseline, pre- and post-warm up and post-exercise for the analysis of pH plus lactate and glucose concentration, while plasma [PSE] was measured at baseline, pre-warm up and post-exercise. Results: Pseudoephedrine in doses of 2.8 mg kg−1 and 2.3 mg kg−1 BM did not significantly improve cycling TT performance compared to PLA (23:28.0 ± 2:07.4 min; 24:48.9 ± 2:13.0 min; 25:09.6 ± 2:18.6 min, respectively; p = 0.60). Plasma [PSE] increased from pre-warm up to post-exercise in both treatment conditions (630.2 ± 127.2 ng/mL; 834.0 ± 86.3 ng/mL 2.3 mg kg−1 ; p < 0.001 vs. 806.1 ± 204.1 ng/mL; 953.3 ± 146.9 ng/mL

18 Effect of a high carbohydrate meal on serum caffeine concentrations following caffeine ingestion T. Skinner 1,∗ , J. Folling 1 , M. Leveritt 2 , J. Coombes 1 , D. Taaffe 1 , D. Jenkins 1 1 The

University of Queensland, Australia University, Australia

2 Griffith

Introduction: This study compared changes in serum concentrations of caffeine between two doses of caffeine (6 and 9 mg kg−1 ) in fed and fasted conditions. It was hypothesised that peak serum caffeine concentrations would be delayed and the total amount of caffeine would be reduced in the fed trials. Methods: 14 healthy, active males (age 24.8 ± 3.7 yrs, body mass 74.2 ± 5.6 kg) randomly completed four trials, each separated by at least five days. Subjects fasted for 12 h prior to each trial; on arrival at the laboratory subjects either remained fasted or consumed a carbohydrate meal (2 g kg−1 CHO) prior to consuming either 6 or 9 mg kg−1 anhydrous caffeine. Venous blood was sampled for serum caffeine at baseline and at six time-points over four hours following caffeine intake. Subjects remained at rest throughout each trial. Testing procedures were approved by The University of Queensland’s ethics committee and all participants provided written informed consent. Data were analysed using one- and two-way repeated measures analysis of variance and inter-subject variability was assessed using coefficient of variance. Results: There was a significant time and interaction effect between conditions (p < 0.001). Peak serum caffeine concentration occurred 60 min following ingestion for both 6 mg kg−1 fasted (p = 0.001) and 9 mg kg−1 fasted (p < 0.001) whilst time to peak concentration occurred at 120 and 180 min following ingestion for 6 and 9 mg kg−1 fed (p < 0.001), respectively. Mean serum caffeine concentrations over four hours were significantly greater (p = 0.001) in the 9 mg kg−1 fasted trial (58.7 ␮mol L−1 ), whilst 6 mg kg−1 fed (27.5 ␮mol L−1 ) was significantly reduced (p = 0.001) compared to the other conditions. There was no difference between 9 mg kg−1 fed (38.8 ␮mol L−1 ) and 6 mg kg−1 fasted (36.1 ␮mol L−1 ) concentrations (p = 0.016). Conclu-