Run Sprint Interval Training Improves Aerobic Performance but Not Max Cardiac Output.
1 Exercise Nutrition Research Laboratory, The University of Western Ontario, School of Kinesiology, Faculty of Health Sciences, London, ON N6A 3K7 2 Centre for Activity and Aging, The University of Western Ontario, School of Kinesiology, Faculty of Health Sciences, London, ON N6A 3K7.
Abstract
Repeated maximal intensity, short duration exercise (sprint interval training, SIT) can produce muscle adaptations similar to endurance training (ET) despite a much reduced training volume. However, most SIT data utilize cycling and little is known about its effects on body composition or maximal cardiac output (Qmax).
PURPOSE: To assess body composition, 2000m run time trial, VO2max, and Qmax effects of run SIT vs ET.
METHODS: Men and women (n=10 per group; 24+/-3 y) trained 3.wk for 6 wk with SIT: 30 sec all-out run sprints (manually driven treadmill), 4-6 bouts.session, 4 min recovery/bout vs ET: 65% VO2max for 30-60 min.d.
RESULTS: Training improved (p<0.05) body composition, 2000m run time trial performance, and VO2max in both groups. Fat mass decreased 12.4% with SIT (13.7+/-1.6 to 12.0+/-1.6 kg) and 5.8% with ET (13.9+/-1.7 to 13.1+/-1.6 kg; mean+/-SEM). Lean mass increased 1% in both groups. Time trial performance improved 4.6% with SIT (-25.6+/-8.1 sec) and 5.9% with ET (-31.9+/-6.3 sec). VO2max increased 11.5% with SIT (46.8+/-1.6 to 52.2+/-2.0 ml.kg..min) and 12.5% with ET (44.0+/-2.0 to 49.5+/-2.6 ml.kg.min). None of these improvements differed between groups. In contrast, Qmax increased by 9.5% with ET only (22.2+/-2.0 to 24.3+/-1.6 L.min).
CONCLUSION: Despite a fraction of the time commitment, run SIT induces similar body composition, VO2max, and performance adaptations as ET, but with no effect on Qmax. These data suggest that adaptations with ET are of central origin primarily whereas those with SIT are more peripheral.
Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women.
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada. jtalania@uoguelph.ca
Abstract
Our aim was to examine the effects of seven high-intensity aerobic interval training (HIIT) sessions over 2 wk on skeletal muscle fuel content, mitochondrial enzyme activities, fatty acid transport proteins, peak O(2) consumption (Vo(2 peak)), and whole body metabolic, hormonal, and cardiovascular responses to exercise. Eight women (22.1 +/- 0.2 yr old, 65.0 +/- 2.2 kg body wt, 2.36 +/- 0.24 l/min Vo(2 peak)) performed a Vo(2 peak) test and a 60-min cycling trial at approximately 60% Vo(2 peak) before and after training. Each session consisted of ten 4-min bouts at approximately 90% Vo(2 peak) with 2 min of rest between intervals. Training increased Vo(2 peak) by 13%. After HIIT, plasma epinephrine and heart rate were lower during the final 30 min of the 60-min cycling trial at approximately 60% pretraining Vo(2 peak). Exercise whole body fat oxidation increased by 36% (from 15.0 +/- 2.4 to 20.4 +/- 2.5 g) after HIIT. Resting muscle glycogen and triacylglycerol contents were unaffected by HIIT, but net glycogen use was reduced during the posttraining 60-min cycling trial. HIIT significantly increased muscle mitochondrial beta-hydroxyacyl-CoA dehydrogenase (15.44 +/- 1.57 and 20.35 +/- 1.40 mmol.min(-1).kg wet mass(-1) before and after training, respectively) and citrate synthase (24.45 +/- 1.89 and 29.31 +/- 1.64 mmol.min(-1).kg wet mass(-1) before and after training, respectively) maximal activities by 32% and 20%, while cytoplasmic hormone-sensitive lipase protein content was not significantly increased. Total muscle plasma membrane fatty acid-binding protein content increased significantly (25%), whereas fatty acid translocase/CD36 content was unaffected after HIIT. In summary, seven sessions of HIIT over 2 wk induced marked increases in whole body and skeletal muscle capacity for fatty acid oxidation during exercise in moderately active women.
Impact of exercise intensity on body fatness and skeletal muscle metabolism.
Physical Activity Sciences Laboratory, Laval University, Ste-Foy, Quebec, Canada.
Abstract
The impact of two different modes of training on body fatness and skeletal muscle metabolism was investigated in young adults who were subjected to either a 20-week endurance-training (ET) program (eight men and nine women) or a 15-week high-intensity intermittent-training (HIIT) program (five men and five women). The mean estimated total energy cost of the ET program was 120.4 MJ, whereas the corresponding value for the HIIT program was 57.9 MJ. Despite its lower energy cost, the HIIT program induced a more pronounced reduction in subcutaneous adiposity compared with the ET program. When corrected for the energy cost of training, the decrease in the sum of six subcutaneous skinfolds induced by the HIIT program was ninefold greater than by the ET program. Muscle biopsies obtained in the vastus lateralis before and after training showed that both training programs increased similarly the level of the citric acid cycle enzymatic marker. On the other hand, the activity of muscle glycolytic enzymes was increased by the HIIT program, whereas a decrease was observed following the ET program. The enhancing effect of training on muscle 3-hydroxyacyl coenzyme A dehydrogenase (HADH) enzyme activity, a marker of the activity of beta-oxidation, was significantly greater after the HIIT program. In conclusion, these results reinforce the notion that for a given level of energy expenditure, vigorous exercise favors negative energy and lipid balance to a greater extent than exercise of low to moderate intensity. Moreover, the metabolic adaptations taking place in the skeletal muscle in response to the HIIT program appear to favor the process of lipid oxidation.
Effect of an acute period of resistance exercise on excess post-exercise oxygen consumption: implications for body mass management.
Present address: Department of Biological Sciences, Ohio University, 128 Irvine Hall, Athens, OH 45701, USA. mschuenke@hotmail.com
Abstract
Studies have shown metabolism to remain elevated for hours following resistance exercise, but none have gone beyond 16 h, nor have they followed a whole body, high intensity exercise protocol. To examine the duration of excess post-exercise oxygen consumption (EPOC) following a period of heavy resistance exercise, seven healthy men [mean (SD) age 22 (3) years, height 177 (8) cm, mass 83 (10) kg, percentage body fat 10.4 (4.2)%] engaged in a 31 min period of resistance exercise, consisting of four circuits of bench press, power cleans, and squats. Each set was performed using the subject's own predetermined ten-repetition maximum and continued until failure. Oxygen consumption ( ) measurements were obtained at consistent times (34 h pre-, 29 h pre-, 24 h pre-, 10 h pre-, 5 h pre-, immediately post-, 14 h post-, 19 h post-, 24 h post-, 38 h post-, 43 h post-, and 48 h post-exercise). Post-exercise measurements were compared to the baseline measurements made at the same time of day. The was significantly elevated ( P<0.05) above baseline values at immediately post, 14, 19, and 38 h post-exercise. Mean daily values for both post-exercise days were also significantly elevated above the mean value for the baseline day. These results suggest that EPOC duration following resistance exercise extends well beyond the previously reported duration of 16 h. The duration and magnitude of the EPOC observed in this study indicates the importance of future research to examine a possible role for high intensity resistance training in a weight management program for various populations.
