Higher-intensity aerobic training programmes, supplemented by resistance training, have been recommended and deemed safe for cardiac rehabilitation patients by many authorities. Based on research evidence, this may also provide superior outcomes for patients and should therefore be considered when developing an international consensus for exercise prescription in cardiac rehabilitation.

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Muscular strength has been identified for the first time as an independent and powerful predictor of better insulin sensitivity in children. Lower strength, CRF and higher central adiposity are highly predictive of higher levels of insulin resistance in this cohort, and should be considered potential targets for interventions designed to enhance metabolic fitness in children and adolescents.

Background: High-intensity progressive resistance training (PRT) improves adiposity and metabolic risk in adults, but has not been investigated in children within a randomized controlled trial (RCT). Objective: We hypothesized that high-intensity PRT (8 weeks, twice a week) would decrease central adiposity in children, as assessed via waist circumference. Methods Design/Setting/Participants: Concealed randomization stratified by age and gender was used to allocate rural New Zealand school students to the wait-list control or PRT group. Intervention: Participants were prescribed two sets (eight repetitions per set) of 11 exercises targeting all the major muscle groups at high intensity. Primary Outcome: Waist circumference; secondary outcomes included whole body fat, muscular fitness (one repetition maximum), cardiorespiratory fitness (peak oxygen consumption during a treadmill test), lipids, insulin sensitivity and fasting glucose. Results: Of the 78 children (32 girls and 46 boys; mean age 12.2(1.3) years), 51% were either overweight (33%) or obese (18%). High-intensity PRT significantly improved waist circumference (mean change PRT À0.8 (2.2) cm vs þ 0.5 (1.7) cm control; F ¼ 7.59, P ¼ 0.008), fat mass (mean change PRT þ 0.2 (1.4) kg vs þ 1.0 (1.2) kg control; F ¼ 6.00, P ¼ 0.017), percent body fat (mean change PRT -0.3 (1.8)% vs þ 1.2 (2.1)% control; F ¼ 9.04, P ¼ 0.004), body mass index (mean change PRT À0.01 (0.8) kg m À2 vs þ 0.4 (0.7) kg m À2 control; F ¼ 6.02, P ¼ 0.017), upper body strength (mean change PRT þ 11.6(6.1) kg vs þ 2.9(3.7) kg control; F ¼ 48.6, Po0.001) and lower body strength (mean change PRT þ 42.9(26.6) kg vs þ 28.5(26.6) kg control; F ¼ 4.72, P ¼ 0.034) compared to the control group. Waist circumference decreased the most in those with the greatest baseline relative strength (r ¼ À0.257, P ¼ 0.036), and greatest relative (r ¼ À0.400, P ¼ 0.001) and absolute (r ¼ 0.340, P ¼ 0.006) strength gains during the intervention. Conclusion: Isolated high-intensity PRT significantly improves central and whole body adiposity in association with muscle strength in normal-weight and overweight children. The clinical relevance and sustainability of these changes in adiposity should be addressed in future long-term studies.