The Effect of Strength Training on Performance in Endurance Athletes
Systematic review of 26 controlled studies: strength training improved time-trial performance, economy, velocity/power at VO2max and vMART in trained endurance athletes
Note on study type
This paper is a systematic review, not a formal meta-analysis — findings are synthesized narratively across 26 studies rather than pooled into a single SMD. Prior versions of this entry reported pooled effect sizes (e.g., "TT +3.1%, SMD=0.45"); those numbers are not from Beattie 2014 and have been removed. For pooled meta-analytic effect sizes in this domain use REF-074 Berryman 2018 (running); REF-158 Pallarés 2025 is a cycling RCT, not a meta-analysis.
Participants / Scope
26 studies meeting inclusion criteria (MEDLINE, PubMed, ScienceDirect, SPORTDiscus, Web of Science); all reviewed with the PEDro scale
Breakdown by sport (full text, checked 2026-09-28: author manuscript, University of Limerick repository, Results): 8 running, 9 cycling, 6 cross-country skiing, 3 triathlon
Athlete criteria: trained endurance athletes with ≥6 months endurance training, training ≥6 h/week OR VO2max ≥50 ml/kg/min
Strength interventions ≥5 weeks, control groups required
Key Findings (qualitative synthesis)
Strength training improved time-trial performance, economy, velocity/power at VO2max and vMART (maximal anaerobic running velocity — endurance-specific muscle power) in competitive endurance athletes
Authors' framing: economy, v/pVO2max and vMART are now thought to be the best performance predictors in elite endurance athletes and are partly dictated by the neuromuscular system, which strength training targets
Authors' conclusion: the research supports adding strength training to an endurance athlete's programme for economy, v/pVO2max, muscle power and performance — but further research is needed
Research agenda stated: valid strength assessments (squats, jump squats, drop jumps) across velocities (maximal strength ↔ strength-speed ↔ speed-strength ↔ reactive strength), and appropriate programmes over >6 months for optimal transfer
Practical Application
Systematic review of 26 controlled studies (≥5-week strength interventions) in trained endurance athletes across running, cycling, cross-country skiing and triathlon: strength training improved time-trial performance, economy, velocity/power at VO2max and vMART — so a trained endurance athlete should expect strength work to improve economy and race performance, not just injury resilience; the review gives no pooled magnitude.
Not from this paper (general practice; see REF-074, a meta-analysis, and REF-158, an RCT): 2-3 strength sessions/week, lower body, heavy load, 4-8 RM core movements, for ≥6 weeks, with economy gains typically appearing after 6-8 weeks.
Limitations
Qualitative synthesis only — no pooled effect sizes with confidence intervals
Heterogeneity of strength protocols (1RM range, volume, frequency) across included studies
Long-term adaptations are under-characterized: the authors call for long-term interventions (>6 months) for optimal transfer to performance
Small female athlete representation
Deprecation note
REF-027 (earlier duplicate entry of the same paper, listing different/unverified SMD values) is deprecated. Use this entry.
How this entry was checked and changed
Content correction 2026-09-27
Sport "cycling, running, swimming" -> running, cycling, xc-skiing, triathlon (the sports the included studies cover; swimming was not among them).
"Economy improvements of 2-8%", "VO2max +1-2%", "effects larger in less-trained athletes" -> not traceable to the abstract; removed.
Dosing (2-3 sessions/week, 4-8 RM, 6-8 weeks) marked as general practice, not from this review; the 8/9/6/3 sport breakdown marked as full text.
Second pass 2026-09-27 (number-by-number check against the abstract): "most included studies <12 weeks" is not in the abstract and was removed; the authors' call for >6-month interventions is.
Cross-reference descriptions checked against the cited entries' current content; wrong years, wrong entries and claims the cited entry does not make were corrected.
Resync 2026-09-28: Called REF-158 a cycling meta-analysis / pooled dosing -> an RCT.
2026-09-28: lines labelled "full text; not checked" read against the open-access full text (author manuscript, researchrepository.ul.ie, hdl 10344/4182): 1 confirmed, 0 corrected, 0 removed.