Effects of resistance training on performance in previously trained endurance runners: A systematic review.

Endurance runners who are already well trained often wonder whether adding strength work to their routine is worth the time, given that running itself demands most of their training hours. This review pulled together 18 randomized controlled trials, involving 321 trained runners, that tested resistance training alongside running programmes. Across these studies, resistance training was generally linked to improvements in muscular strength, running economy, muscle power, and race performance over distances from 1,500 to 10,000 metres, without apparent increases in body mass or signs of overtraining. What makes this interesting is that strength and endurance training are sometimes assumed to interfere with each other, yet the pattern here leans toward compatibility.

However, the improvements did not appear in every study, and the authors note meaningful methodological inconsistencies across the trials, meaning the results should be read with some caution rather than as a settled conclusion.

If you're a serious runner, you may have wondered whether lifting weights could actually help your running, or whether it just adds fatigue without real benefit. This review looked at 18 studies involving 321 runners who already had running training behind them, comparing what happened when resistance training was added to their programmes. Overall, the runners who did resistance training tended to show improvements in strength, running economy (how efficiently the body uses oxygen while running), power, and performance in races between 1,500 and 10,000 metres.

Importantly, these gains didn't come with unwanted weight gain or signs of excessive training stress, based on what these studies reported. That said, not every study found the same benefits, and the researchers point out that differences in how the resistance training programmes were designed and run make it hard to draw firm, one-size-fits-all conclusions. So while the overall pattern is encouraging, exactly which type of strength training works best, and for whom, remains unclear from this evidence alone.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

For physiotherapists working with trained distance runners, a recurring question is whether recommending or supporting a resistance training component alongside running load actually translates into measurable gains, or risks counterproductive fatigue. This systematic review synthesises 18 randomized controlled trials across 321 already-trained endurance runners and informs that question directly, rather than addressing novice or untrained populations. Across the included trials, resistance training was associated with improvements in muscular strength, running economy, muscle power indices, and direct race performance over 1,500 to 10,000 metres, without evidence of increased body mass or overtraining markers in these studies.

This raises the possibility that concurrent strength and endurance training, in this trained population, need not conflict, though the review stops short of identifying which specific resistance protocols (load, volume, exercise selection) reliably produce these effects, since benefits were inconsistent across trials. The authors explicitly flag methodological inconsistencies among the included studies as a reason for cautious interpretation, and the review does not report a formal risk-of-bias synthesis score or pooled effect size, so the magnitude and certainty of the overall benefit cannot be precisely quantified from the abstract. This evidence informs the plausibility of resistance training as a complementary strategy for trained runners but does not establish an optimal or standardized protocol.