***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: PURPOSE High-intensity interval training ( HIIT ) is a potential alternative to traditionally recommended steady state exercise for providing health benefits in adolescents , yet its dose-response relationship in this cohort remains unclear , as does its translatability to real-world , non clinical setting s. The present study adopts a novel dose-response design to investigate the effects of undertaking 8 wk of HIIT on the cardiometabolic health of low-active male adolescents . METHODS Twenty-six male adolescents ( age 16 ± 1 yr ) , identified as low active by nonparticipation in structured sport and physical education classes  , were r and omly assigned to one of five treatment groups . Corresponding with their group numbers ( 1 - 5 ) , participants completed a number of HIIT " sets , " which consisted of 4 repeated bouts of 20-s near-maximal exertion interspersed with 10-s passive recovery . Participants performed two HIIT sessions and one resistance training session each week for 8 wk . Baseline and follow-up health measures consisted of peak oxygen uptake ( V˙O2peak ) with an incremental ramp test to volitional exhaustion ; body composition ( including visceral fat mass , body fat , and lean tissue mass ) with dual-energy x-ray absorptiometry ; and lipid profile , glucose , insulin , and interleukin-6 from blood analysis . All health outcomes were analyzed as percentage changes , and data were modeled using a quadratic function to explore dose-response relationships . RESULTS Significant improvements were observed for V˙O2peak ( ∼6 % ) , body fat percentage ( ∼4 % ) , visceral fat mass ( ∼10 % ) , and waist circumference-to-height ratio ( ∼3 % ) , but there was no clear effect of dose across groups . CONCLUSIONS Low-active adolescent males performing a single HIIT set twice weekly , in addition to one resistance training session , gained meaningful improvements in fitness and body composition . Performing additional HIIT sets provided no additional improvements to those of the lowest dose in this study Purpose To compare two modalities of exercise training ( i.e. , Endurance Training [ ET ] and High-Intensity Interval Training [ HIT ] ) on health-related parameters in obese children aged between 8 and 12 years . Methods Thirty obese children were r and omly allocated into either the ET or HIT group . The ET group performed a 30 to 60-minute continuous exercise at 80 % of the peak heart rate ( HR ) . The HIT group training performed 3 to 6 sets of 60-s sprint at 100 % of the peak velocity interspersed by a 3-min active recovery period at 50 % of the exercise velocity . HIT sessions last ∼70 % less than ET sessions . At baseline and after 12 weeks of intervention , aerobic fitness , body composition and metabolic parameters were assessed . Results Both the absolute ( ET : 26.0 % ; HIT : 19.0 % ) and the relative VO2 peak ( ET : 13.1 % ; HIT : 14.6 % ) were significantly increased in both groups after the intervention . Additionally , the total time of exercise ( ET : 19.5 % ; HIT : 16.4 % ) and the peak velocity during the maximal grade d cardiorespiratory test ( ET : 16.9 % ; HIT : 13.4 % ) were significantly improved across interventions . Insulinemia ( ET : 29.4 % ; HIT : 30.5 % ) and HOMA-index ( ET : 42.8 % ; HIT : 37.0 % ) were significantly lower for both groups at POST when compared to PRE . Body mass was significantly reduced in the HIT ( 2.6 % ) , but not in the ET group ( 1.2 % ) . A significant reduction in BMI was observed for both groups after the intervention ( ET : 3.0 % ; HIT : 5.0 % ) . The responsiveness analysis revealed a very similar pattern of the most responsive variables among groups . Conclusion HIT and ET were equally effective in improving important health related parameters in obese youth The aim of the study was to examine the effects of two different training programs ( high-intensity-training vs. continuous endurance training ) on aerobic power and body composition in recreationally active men and women and to test whether or not participants were able to complete a half marathon after the intervention period . Thirty-four recreational endurance runners were r and omly assigned either to a Weekend-Group ( WE , n = 17 ) or an After-Work- Group ( AW , n = 17 ) for a 12 week-intervention period . WE weekly completed 2 h 30 min of continuous endurance running composed of 2 sessions on the weekend . In contrast , AW performed 4 30 min sessions of high intensity training and an additional 30 min endurance run weekly , always after work . During an exhaustive treadmill test  aerobic power was measured and heart rate was continuously recorded . Body composition was assessed using bio-impedance . Following the intervention period all subjects took part in a half-marathon . AW significantly improved peak oxygen uptake ( VO2 peak ) from 36.8 ± 4.5 to 43.6 ± 6.5 [ mL.min(-1).kg(-1 ) ] , velocity at lactate threshold ( VLT ) from 9.7 ± 2.2 to 11.7 ± 1.8 [ km.h(-1 ) ] and visceral fat from 5.6 ± 2.2 to 4.7 ± 1.9 In WE VO2 peak signifi-cantly increased from 38.8 ± 5.0 to 41.5 ± 6.0 [ mL.min(-1).kg(-1 ) ] , VLT from 9.9 ± 1.3 to 11.2 ± 1.7 [ km.h(-1 ) ] and visceral fat was reduced from 5.7 ± 2.1 to 5.4 ± 1.9 ( p < 0.01 ) . Only the improvements of VO2 peak were significantly greater in AW compared with WE ( pre/post group interaction : F=15.4 , p = 0.01 , η(2 ) = 0.36 ) . Both groups completed a half marathon with no significant differences in performance ( p = 0.63 ) . Short , intensive endurance training sessions of about 30 min are effective in improving aerobic fitness in recreationally active runners . Key pointsContinuous endurance training and high intensity training lead to significant improvements of aerobic capacity and body compositionBoth training methods enable recreationally active runners to finish a half-marathonHigh intensity training is favorable to improve VO2 peak Abstract This study examined the effects of a 6-week intermittent exercise training , at different intensities , on body composition , functional walking and aerobic endurance in overweight children . Forty-eight overweight children ( age : 10.4 ± 0.9 years ) were r and omly assigned to either intervention or control group . Lower and higher intensity intermittent exercise groups ( LIIE and HIIE ) performed intermittent running three times a week . LIIE performed more intervals at a lower intensity [ 16 intervals at 100 % of individual maximal aerobic speed ( MAS ) , 8 minutes in total ] , and HIIE performed fewer intervals at a higher intensity ( 12 intervals at 120 % of MAS , 6 minutes in total ) . Each interval consisted of a 15-second run at the required speed , followed by a 15-second passive recovery . After 6 weeks , HIIE had a significantly ( p < 0.05 ) higher percentage reduction in sum of skinfolds ( i.e. calf and triceps ) , and significantly ( p < 0.05 ) fewer steps during the functional obstacle performance , as compared with LIIE and control group . Significant improvement ( p < 0.05 ) was found in intermittent aerobic endurance for HIIE as compared to the control group . Higher intensity intermittent training is an effective and time-efficient intervention for improving body composition , functional walking and aerobic endurance in overweight children BACKGROUND Obesity and poor physical fitness constitute a health problem affecting an increasing number of children . Causes include a pervasive " toxic " environment that facilitates increased caloric intake and reduced physical activity . An effective strategy for prevention and treatment of childhood obesity likely includes a collaborative effort in the school setting . OBJECTIVE To determine whether a school-based fitness program can improve body composition , cardiovascular fitness level , and insulin sensitivity in overweight children . DESIGN Fifty overweight middle school children with a body mass index ( BMI ) above the 95th percentile for age were r and omized to lifestyle-focused , fitness-oriented gym classes ( treatment group ) or st and ard gym classes ( control group ) for 9 months . Children underwent evaluation of  fasting insulin and glucose levels , body composition by means of  dual energy absorptiometry , and maximum oxygen consumption ( V0(2)max ) treadmill testing  at baseline ( before the school year ) and at end of the school year . SETTING S Rural middle school and an academic children 's hospital . MAIN OUTCOME MEASURES Baseline test results for cardiovascular fitness , body composition , and fasting insulin and glucose levels . RESULTS At baseline , there were no differences between groups before intervention ( values for age , 12 + /- 0.5 years [ all results , mean + /- SD ] ; BMI [ calculated as weight in kilograms divided by the square of height in meters ] , 31.0 + /- 3.7 ; percentage of body fat , 36.5 % + /- 4.6 % ; lean body mass , 41.4 + /- 8.6 kg ; and V0(2)max , 31.5 + /- 5.1 mL/kg per minute ) . Compared with the control group , the treatment group demonstrated a significantly greater loss of body fat ( loss , -4.1 % + /- 3.4 % vs -1.9 % + /- 2.3 % ; P = .04 ) , greater increase in cardiovascular fitness ( V0(2)max , 2.7 + /- 2.6 vs 0.4 + /- 3.3 mL/kg per minute ; P<.001 ) , and greater improvement in fasting insulin level ( insulin level , -5.1 + /- 5.2 vs 3.0 + /- 14.3 microIU/mL [ -35.4 + /- 36.1 vs 20.8 + /- 99.3 pmol/L ] ; P = .02 ) . CONCLUSIONS Children enrolled in fitness-oriented gym classes showed greater loss of body fat , increase in cardiovascular fitness , and improvement in fasting insulin levels than control subjects . The modification to the school physical education curriculum demonstrates that small but consistent changes in the amount of physical activity has beneficial effects on body composition , fitness , and insulin levels in children . Partnering with school districts should be a part of a public health approach to improving the health of overweight children The aim of the present study was to compare the effects of a multidisciplinary approach ( MTG ) and aerobic interval training ( AIT ) on cardiovascular risk factors in overweight adolescents . A total of 62 overweight and obese adolescents from Trøndelag County in Norway , referred to medical treatment at St Olav 's Hospital , Trondheim , Norway , were invited to participate . Of these , 54 adolescents ( age , 14.0 + /- 0.3 years ) were r and omized to either AIT ( 4 x 4 min intervals at 90 % of maximal heart rate , each interval separated by 3 min at 70 % , twice a week for 3 months ) or to MTG ( exercise , dietary and psychological advice , twice a month for 12 months ) . Follow-up testing occurred at 3 and 12 months . VO(2max ) ( maximal oxygen uptake ) increased more after AIT compared with MTG , both at 3 months ( 11 compared with 0 % ; P<0.01 ) and 12 months ( 12 compared with -1 % ; P<0.01 ) .  AIT enhanced endothelial function compared with MTG at both 3 months ( absolute change , 5.1 compared with 3.9 % ; P<0.01 ) and 12 months ( absolute change , 6.3 compared with 1.0 % ; P<0.01 ) . AIT was favourable compared with MTG in reducing BMI ( body mass index ) , percentage of fat , MAP ( mean arterial blood pressure ) and increasing peak oxygen pulse . In addition , AIT induced a more favourable regulation of blood glucose and insulin compared with MTG . In conclusion , the novel findings of the present proof-of-concept study was that 3 months of twice weekly high-intensity exercise sessions reduced several known cardiovascular risk factors  in obese adolescents more than that observed after a multitreatment strategy , which was initiated as hospital treatment . Follow-up at 12 months confirmed that AIT improved or maintained these risk factors to a better degree than MTG Background : The chronic effects of high-intensity endurance training on metabolic health outcomes in overweight adolescents remains poorly understood . Objective : To test the hypothesis that high-intensity endurance training ( ET ) is superior to moderate-intensity ET for improving risk factors for type 2 diabetes in overweight adolescents . Design and methods : In this r and omized trial , 106 overweight and obese adolescents ( 15.2 years ; 76 % female ; 62 % Caucasian ) were r and omly assigned to high-intensity ET ( 70–85 % of heart rate reserve , n=38 ) , moderate-intensity ET ( 40–55 % heart rate 
    Output:
    
The inclusion of HIIT programmes improved maximal oxygen uptake ( VO2max ) , performance in the intermittent Yo-Yo test and maximal aerobic speed .
Conclusions The HIIT programmes showed improvements in the variables studied , with interventions two or three times weekly .