Cardio for the engine, weights for the muscle: older adults may need both

From middle age onwards, two things quietly decline: the capacity of the heart and lungs, and the amount of lean muscle. Cardiorespiratory fitness is one of the strongest markers of how well people age, while lean mass underpins strength and independence. Aerobic training and resistance training are the two main tools, but time is finite and many people effectively choose one. This review asked which type of training does more for fitness and body composition in middle-aged and older adults, tested head to head.

The authors searched four databases plus the reference lists of included trials up to April 2024 for randomised controlled trials directly comparing aerobic training with resistance training in middle-aged to older adults. Thirty-eight trials with a pooled sample of 1682 participants met the inclusion criteria. Results were combined as mean differences for outcomes including VO2max or VO2peak, six-minute walk distance, body mass and lean body mass. Subgroups were examined by health status, sex, intervention length and age above or below 65.

Aerobic training beat resistance training for cardiorespiratory fitness, improving VO2max or VO2peak by a mean difference of 1.80 and six-minute walk performance by 18.58. It also reduced body mass more, by a mean difference of 1.23. Lean body mass moved the other way, favouring resistance training. The aerobic advantage in fitness held in both healthy and unhealthy participants, in men and women, in interventions shorter and longer than 24 weeks, and in people aged 65 and under as well as over 65.

The direction of the result matches physiological expectation, but the value is in the size and consistency of the pooled comparison across 38 trials. It confirms that neither training style substitutes for the other: aerobic work drives the fitness measures most tied to healthy ageing, while lifting is what preserves lean mass. The authors themselves conclude a combination is likely optimal. What the review cannot answer is how best to split limited weekly training time between the two.

If you only ever do one type of exercise, this is a clear account of what you are leaving on the table. Aerobic training was the stronger lever for the heart and lung fitness that declines with age, and it shifted body mass more. Resistance training earned its keep on lean mass, the tissue that guards strength in later life. The findings are a reason to think of the two as complements rather than rivals.