***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The aim of this study was to investigate the effects of very high intensity sprint interval training ( SIT ) on metabolic and vascular risk factors in overweight/obese sedentary men . Ten men ( age , 32.1 ± 8.7 years ; body mass index , 31.0 ± 3.7 kg m(-2 ) ) participated . After baseline metabolic , anthropometric , and fitness measurements , participants completed a 2-week SIT intervention , comprising 6 sessions of 4 to 6 repeats of 30-second Wingate anaerobic sprints on an electromagnetically braked cycle ergometer , with 4.5-minute recovery between each repetition . Metabolic , anthropometric , and fitness assessment s were repeated post-intervention . Both maximal oxygen uptake ( 2.98 ± 0.15 vs 3.23 ± 0.14 L min(-1 ) , P = .013 ) and mean Wingate power ( 579 ± 24 vs 600 ± 19 W , P = .040 ) significantly increased after 2 weeks of  SIT . Insulin sensitivity index ( 5.35 ± 0.72 vs 4.34 ± 0.72 , P = .027 ) and resting fat oxidation rate in the fasted state ( 0.13 ± 0.01 vs 0.11 ± 0.01 g min(-1 ) , P = .019 ) were significantly higher and systolic blood pressure ( 121 ± 3 vs 127 ± 3 mm Hg , P = .020 ) and resting carbohydrate oxidation in the fasted state ( 0.03 ± 0.01 vs 0.08 ± 0.02 g min(-1 ) , P = .037 ) were significantly lower 24 hours post-intervention compared with baseline , but these changes were no longer significant 72 hours post-intervention . Significant decreases in waist ( 98.9 ± 3.1 vs 101.3 ± 2.7 cm , P = .004 ) and hip ( 109.8 ± 2.2 vs 110.9 ± 2.2 cm , P = .017 ) circumferences compared with baseline were also observed after the intervention . Thus , 2 weeks of SIT substantially improved a number of metabolic and vascular risk factors in overweight/obese sedentary men , highlighting the potential for this to provide an alternative exercise model for the improvement of vascular and metabolic health in this population We found that interval training provides an effective means to improve the cardiovascular fitness and health status of highly functional patients with coronary artery disease . We also revealed that interval training improves anaerobic tolerance to a greater extent than the traditional exercise training model without increasing the risk to the patient . This research supports the implementation of interval training for highly functional patients with coronary artery disease Our purpose was to examine the effects of sprint interval training on muscle glycolytic and oxidative enzyme activity and exercise performance .  Twelve healthy men ( 22 + /- 2 yr of age ) underwent intense interval training on a cycle ergometer for 7 wk . Training consisted of 30-s maximum sprint efforts ( Wingate protocol ) interspersed by 2 - 4 min of recovery , performed three times per week . The program began with four intervals with 4 min of recovery per session in week 1 and progressed to 10 intervals with 2.5 min of recovery per session by week 7 . Peak power output and total work over repeated maximal 30-s efforts and maximal oxygen consumption ( VO2 max ) were measured before and after the training program . Needle biopsies were taken from vastus lateralis of nine subjects before and after the program and assayed for the maximal activity of hexokinase , total glycogen phosphorylase , phosphofructokinase , lactate dehydrogenase , citrate synthase , succinate dehydrogenase , malate dehydrogenase , and 3-hydroxyacyl-CoA dehydrogenase . The training program result ed in significant increases in peak power output , total work over 30 s , and VO2 max . Maximal enzyme activity of hexokinase , phosphofructokinase , citrate synthase , succinate dehydrogenase , and malate dehydrogenase was also significantly ( P < 0.05 ) higher after training . It was concluded that relatively brief but intense sprint training can result in an increase in both glycolytic and oxidative enzyme activity , maximum short-term power output , and VO2 max UNLABELLED 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 use cycling , and little is known about its effects on body composition or maximal cardiac output ( Qmax ) . PURPOSE The purpose of this study was to assess body composition , 2000-m run time trial , VO(2max ) , and Q(max ) effects of run SIT versus ET . METHODS Men and women ( n = 10 per group ; mean ± SD : age = 24 ± 3 yr ) trained three times per week for  6 wk with SIT , 30-s all-out run sprints ( manually driven treadmill ) , four to six bouts per session , 4-min recovery per bout , versus ET , 65 % VO(2max ) for 30 to 60 min·d(-1 ) . RESULTS Training improved ( P < 0.05 ) body composition , 2000-m run time trial performance , and VO(2max ) in both groups . Fat mass decreased 12.4 % with SIT ( mean ± SEM ; 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 ) . Lean mass increased 1 % in both groups . Time trial performance improved 4.6 % with SIT ( -25.6 ± 8.1 s ) and 5.9 % with ET ( -31.9 ± 6.3 s ) . VO(2max ) increased 11.5 % with SIT ( 46.8 ± 1.6 to 52.2 ± 2.0 mL·kg·(-1)·min(-1 ) ) and 12.5 % with ET ( 44.0 ± 2.0 to 49.5 ± 2.6 mL·kg·(-1)·min(-1 ) ) . None of these improvements differed between groups . In contrast , Q(max ) increased by 9.5 % with ET only ( 22.2 ± 2.0 to 24.3 ± 1.6 L·min(-1 ) ) . CONCLUSIONS Despite a fraction of the time commitment , run SIT induces similar body composition , VO(2max ) , and performance adaptations as ET , but with no effect on Q(max ) . These data suggest that adaptations with ET are of central origin primarily , whereas those with SIT are more PURPOSE We have investigated the effect of varying the intensity of interval training on 40-km time-trial performance in 20 male endurance cyclists ( peak oxygen uptake 4.8+/-0.6 L x min(-1 ) , mean + /- SD ) . METHODS Cyclists performed a 25-kJ sprint test , an incremental test to determine peak aerobic power ( PP ) and a simulated 40-km time-trial on a Kingcycle ergometer . They were then r and omly assigned to one of five types of interval-training session : 12x30 s at 175 % PP , 12x60 s at 100 % PP , 12x2 min at 90 % PP , 8x4 min at 85 % PP , or 4x8 min at 80 % PP . Cyclists completed 6 sessions over 3 wk , in addition to their usual aerobic base training . All laboratory tests were then repeated . RESULTS Performances in the time trial were highly reliable when controlled for training effects ( coefficient of variation = 1.1 % ) . The percent improvement in the time trial was modeled as a polynomial function of the rank order of the intensity of the training intervals , a procedure vali date d by simulation . The cubic trend was strong and statistically significant ( overall correlation = 0.70 , P = 0.005 ) and predicted greatest enhancement for the intervals performed at 85 % PP ( 2.8 % , 95 % CI = 4.3 - 1.3 % ) and at 175 % PP ( 2.4 % , 95 % CI = 4.0 - 0.7 % ) . Intervals performed at 100 % PP and 80 % PP did not produce statistically significant enhancements of performance . Quadratic and linear trends were weak or insubstantial . CONCLUSIONS Interval training with work bouts close to race-pace enhance 1-h endurance performance ; work bouts at much higher intensity also appear to improve performance , possibly by a different mechanism Parra et al. ( Acta Physiol . Sc and 169 : 157 - 165 , 2000 ) showed that 2 wk of daily sprint interval training ( SIT ) increased citrate synthase ( CS ) maximal activity but did not change " anaerobic " work capacity , possibly because of chronic fatigue induced by daily training . The effect of fewer SIT sessions on muscle oxidative potential is unknown , and aside from changes in peak oxygen uptake ( Vo(2 peak ) ) , no study has examined the effect of SIT on " aerobic " exercise capacity . We tested the hypothesis that six sessions of SIT , performed over 2 wk with 1 - 2 days rest between sessions to promote recovery , would increase CS maximal activity and endurance capacity during cycling at approximately 80 % Vo(2 peak ) . Eight recreationally active subjects [ age = 22 + /- 1 yr ; Vo(2 peak ) = 45 + /- 3 ml.kg(-1).min(-1 ) ( mean + /- SE ) ] were studied before and 3 days after SIT . Each training session consisted of four to seven " all-out " 30-s Wingate tests with 4 min of recovery . After SIT , CS maximal activity increased by 38 % ( 5.5 + /- 1.0 vs. 4.0 + /- 0.7 mmol.kg protein(-1).h(-1 ) ) and resting muscle glycogen content increased by 26 % ( 614 + /- 39 vs. 489 + /- 57 mmol/kg dry wt ) ( both P < 0.05 ) . Most strikingly , cycle endurance capacity increased by 100 % after SIT ( 51 + /- 11 vs. 26 + /- 5 min ; P < 0.05 ) , despite no change in Vo(2 peak ) . The coefficient of variation for the cycle test was 12.0 % , and a control group ( n = 8) showed no change in performance when tested approximately 2 wk apart without SIT . We conclude that short sprint interval training ( approximately 15 min of intense exercise over 2 wk ) increased muscle oxidative potential and doubled endurance capacity during intense aerobic cycling in recreationally active individuals The goal of the study was to determine the effects of continuous ( CT ) vs. intermittent ( IT ) training yielding identical mechanical work and training duration on skeletal muscle and cardiorespiratory adaptations in sedentary subjects . Eleven subjects ( 6 men and 5 women , 45 + /- 3 years ) were r and omly assigned to either of the two 8-wk training programs in a cross-over design , separated by 12 wk of detraining .  Maximal oxygen uptake ( Vo2max ) increased after both trainings ( 9 % with CT vs. 15 % with IT ) , whereas only IT was associated with faster Vo2 kinetics ( tau : 68.0 + /- 1.6 vs. 54.9 + /- 0.7 s , P < 0.05 ) measured during a test to exhaustion ( TTE ) and with improvements in maximal cardiac output ( Qmax , from 18.1 + /- 1.1 to 20.1 + /- 1.2 l/min ; P < 0.01 ) . Skeletal muscle mitochondrial oxidative capacities ( Vmax ) were only increased after IT ( 3.3 + /- 0.4 before and 4.5 + /- 0.6 micromol O2 x min(-1 ) x g dw(-1 ) after training ; P < 0.05 ) , whereas capillary density increased after both trainings , with a two-fold higher enhancement after CT ( + 21 + /- 1 % for IT and + 40 + /- 3 % after CT , P < 0.05 ) . The gain of Vmax was correlated with the gain of TTE and the gain of Vo2max with IT . The gain of Qmax was also correlated with the gain of VO2max . These results suggest that fluctuations of workload and oxygen uptake during training sessions , rather than exercise duration or global energy expenditure , are key factors in improving muscle oxidative capacities . In an integrative view , IT seems optimal in maximizing both peripheral muscle and central cardiorespiratory adaptations , permitting significant functional improvement . These data support the symmorphosis concept in sedentary subjects Very high-intensity , low-volume , sprint interval training ( SIT ) increases muscle oxidative capacity and may increase maximal oxygen uptake ( $ $ { \dot{V}\text{O } } _ { { 2 { \text{max } } } } $ $ ) , but whether circulatory function is improved , and whether SIT is feasible in overweight/obese women is unknown . To examine the effects of SIT on $ $ { \dot{V}\text{O } } _ { { 
    Output:
    
ConclusionS IT improves aerobic capacity in healthy , young people .
Relative to continuous endurance training of moderate intensity , SIT presents an equally effective alternative with a reduced volume of activity .
This evaluation of effects and analysis of moderating variables consoli date s the findings of small- sample studies and contributes to the practical application of SIT to improve cardiorespiratory fitness and health