A new semi-systematic review published in Frontiers in Sports and Active Living has examined how the sequencing of strength and endurance work affects performance in trained endurance runners, and concludes that concurrent training does not interfere with aerobic adaptation provided sessions are appropriately spaced. The paper, which screened 617 studies and synthesised findings from 64 of them, has already been cited in coaching forums for offering the clearest practical guidance to date on a question that has dogged distance coaching for two decades.
The review's central finding is that the order of strength and endurance sessions inside a training week matters far less than the recovery interval between them. When the gap between a strength session and a run is shorter than three hours, the authors note an acute molecular interference effect that suppresses the mTOR signalling pathway involved in muscle protein synthesis. With more than three hours between sessions, that interference effect largely disappears, and the chronic adaptations from each session can run in parallel. The implication for runners juggling double-day schedules is straightforward: keep the gap as wide as your day allows, and ideally split strength and endurance work into morning and evening sessions.
For master runners specifically, the review highlights a separate body of evidence showing that maximal-strength training can produce the largest single performance gain available outside endurance volume itself. One referenced trial reported a 6.17 per cent improvement in running economy at marathon pace following 12 weeks of heavy strength work, with no loss of VO2max in the cohort. The authors make a similar point for younger recreational marathoners but with caveats: short-cycle eight-week interventions tend not to transfer to running economy, even when leg strength rises by double-digit percentages on lab tests.
The paper's authors push back on a common misconception that strength training will compromise easy mileage. Across the studies they reviewed, athletes performing two strength sessions per week alongside their running tolerated the additional load well, with no measurable difference in fatigue indices or perceived recovery scores compared to runners on equivalent endurance-only programmes. The authors do warn, however, that explosive plyometric work demands more recovery than heavy resistance work, and should be programmed away from quality endurance days.
For self-coached marathon runners the practical take-aways are familiar but sharper: keep two strength sessions a week, prefer heavy compound lifts over circuit-style endurance-strength fusion sessions, and protect a three-hour gap before quality runs. The review underlines what elite coaches like Renato Canova have argued for years, but it does so with a fresh and well-organised body of evidence, and without the methodological holes that hampered earlier meta-analyses on the topic. The full paper is available open-access on the Frontiers website.