Mixed training beat cardio alone on teen insulin markers

Cardiometabolic risk factors that appear in adolescence tend to track into adult life, so the authors frame exercise in the teenage years as long-term vascular protection. Aerobic exercise is the usual prescription, but combining it with resistance training is increasingly promoted on the grounds that muscle contributes to glucose handling. The unresolved question is whether the combination genuinely outperforms aerobic training alone, or simply outperforms doing nothing — a distinction that depends entirely on what the control group did. This review set out to test the effects of combined aerobic and resistance training on glucose metabolism, lipid profiles and blood pressure in adolescents with overweight or obesity.

The authors searched PubMed, Web of Science, Embase, The Cochrane Library and Scopus from inception up to 13 May 2026 for randomised controlled trials of combined aerobic and resistance training in adolescents with overweight or obesity. Twelve RCTs met the criteria. Analysis was performed in R, using mean differences with 95% confidence intervals and change-from-baseline values entered into the models. Crucially, hierarchical subgroup analyses were run according to control group type, separating comparisons against non-exercise controls from comparisons against aerobic exercise, using a Hartung-Knapp-Sidik-Jonkman random-effects model. Evidence quality for each outcome was graded with the GRADE approach.

Against non-exercise controls, fasting insulin fell substantially (MD = -17.90 μU/mL, 95% CI -26.04 to -9.76, P < 0.0001), as did systolic pressure (MD = -3.51 mmHg, 95% CI -6.23 to -0.80, P = 0.01) and diastolic pressure (MD = -3.72 mmHg, 95% CI -6.69 to -0.75, P = 0.01). Against aerobic exercise alone, the combination still improved fasting insulin (MD = -2.70 μU/mL, P = 0.01), HOMA-IR (MD = -0.57, P = 0.01) and adiponectin (MD = 2.37 μg/mL, P < 0.0001), with the difference between the two subgroups significant for fasting insulin (P = 0.0004). Blood pressure showed no notable change versus aerobic exercise, and fasting glucose, total cholesterol and triglycerides did not shift in any subgroup, with fasting glucose showing extremely high heterogeneity. GRADE rated fasting insulin, SBP and DBP versus control, plus fasting insulin and HOMA-IR versus aerobic exercise, as moderate quality; everything else was low or very low.

The headline result confirms the unsurprising: structured training beats sedentary controls on insulin and blood pressure. The more interesting contribution is the subgroup structure, which isolates a smaller but still measurable advantage of adding resistance work on top of aerobic exercise for insulin-related markers. The flat glucose, cholesterol and triglyceride results complicate any claim that combined training remodels the whole cardiometabolic profile in adolescents. The authors themselves call for standardised combined protocols, consistent comparator definitions and larger RCTs with longer follow-up, which is a fair summary of what this evidence base still lacks.

This is a reason to think that adding resistance training to cardio has something to offer beyond cardio alone, at least for insulin-related markers in young people carrying excess weight. It is also a reason to keep expectations narrow: fasting glucose and blood lipids did not move, and the blood pressure benefit only appeared against inactive controls. The effect sizes come from a small and heterogeneous set of trials, so the numbers are best treated as directional rather than as a prediction of what any individual would experience. The population is adolescents, and results in adults may differ.},