Lifting weights alone raised VO2max in adults over 60

Cardiorespiratory fitness, measured as VO2max, is one of the better markers of how well an older body handles daily life and physical stress, and it tends to fall with age. Aerobic exercise is the obvious way to defend it, but many older adults train mainly or only with weights. Whether resistance training on its own moves VO2max, and whether some people gain far more from it than others, matters for how such programmes are judged. This analysis set out to test both the average effect and the reality of individual differences in response.

The authors drew on data from a recent meta-analysis of 22 randomised controlled trials of progressive resistance training. Those trials represented 552 men and women aged 60 and over, with 292 assigned to resistance training and 260 to control conditions. The primary outcome was cardiorespiratory fitness expressed as VO2max in ml/kg/min. Using an inverse variance heterogeneity model, they pooled the treatment effect, resistance training minus control, and separately calculated true inter-individual response differences alongside prediction intervals to describe the range of plausible outcomes.

Resistance training produced a statistically significant increase in VO2max averaging 1.8 ml/kg/min compared with control. The trials varied substantially in their results, and the prediction interval ran from a small decrease to a larger gain, meaning individual studies pointed in different directions. When the authors tested for genuine inter-individual response differences, none reached statistical significance: the estimate was 0.6 ml/kg/min with an interval crossing zero. So the average older adult improved slightly, but there was no evidence that the training itself creates strong winners and non-responders.

The result supports the idea that resistance training carries a modest aerobic dividend in older adults rather than being purely a strength stimulus, which fits the observation that lifting can be demanding on the cardiovascular system. At the same time the size of the gain is small next to what aerobic training typically delivers, and the disagreement between trials leaves the true average uncertain. It echoes the same authors' finding on body composition that apparent individual variation in response does not hold up under analysis. Open questions include which resistance protocols drive the effect and whether the pattern extends to younger adults.

If you are over 60 and your training is mostly weights, this is a reason to think your aerobic fitness is not being neglected entirely, even if the improvement is modest. It is not an argument for dropping walking, cycling or other aerobic work, since the average change here is small and the trials were inconsistent. The absence of detectable response differences also means a small gain is the sensible expectation rather than a sign you personally do not respond. Judge the effect as a bonus alongside strength, not as a substitute for cardio.