REF-1281 · Diaz-Canestro & Montero, 2019 · Sports Medicine · Paper · PubMed

Do women gain less VO2max from training than men?

With endurance training, untrained men gained ~2 mL/kg/min more than women in 8 small studies; with identical interval protocols, women and men gained alike (REF-1243).

Main caveat: Read from the abstract only; the included studies, their protocols, durations, intensities, ages and risk of bias could not be checked.
fairly strong evidenceMeasured on non-athletes and recreational people

Diaz-Canestro and Montero asked whether the VO2max gain from endurance training differs between men and women given the same dose. They searched MEDLINE and Web of Science to February 2019 for studies that gave healthy, age-matched men and women a sex-matched dose of endurance training and measured VO2max, and pooled the difference between the sexes' responses.

Eight studies qualified, all in healthy untrained people, 175 in all (90 men, 85 women), with training duration and intensity matched by sex in every study. Men gained more: 191 mL/min (95% CI 99 to 283; P < 0.001) more in absolute VO2max and 1.95 mL/kg/min (0.76 to 3.15; P = 0.001) more relative to body mass.

There was no detectable heterogeneity (I² = 0%, P ≥ 0.59), and the authors report the result was robust to potential moderators. They conclude that aerobic trainability is sexually dimorphic.

Our reading: a consistent pooled difference in untrained adults on endurance training (the modalities are not detailed in the abstract), but from 8 small studies, read from the abstract only.

It sits beside REF-1243 (A-, 28 trials, 965 people), where the same interval protocol raised VO2max by g = 0.57 in both sexes and the raw changes were +0.20 vs +0.32 L/min and +3.34 vs +3.50 mL/kg/min (women vs men), not different.

They disagree: here men gained more in both absolute and relative VO2max, while REF-1243 found no sex difference in either, its raw-unit sensitivity analysis included. REF-1243's authors suggest the gap reflects the training (they describe this review's as moderate-intensity endurance training; HIIT and sprint intervals there) or the method (raw mean differences here, change relative to baseline there), and that a sex difference may be protocol dependent.

Protocol

Design: systematic review and meta-analysis; MEDLINE and Web of Science from inception to February 2019.
Inclusion (abstract): articles assessing the VO2max response to a given sex-matched dose of endurance training in healthy age-matched men and women.
Included: 8 studies; all used common modalities of endurance training in healthy untrained individuals; 175 participants (90 men, 85 women); training duration and intensity sex-matched in all studies.
Analysis: meta-analyses of the mean difference between men's and women's VO2max responses (absolute, mL/min; relative, mL/kg/min); subgroup and meta-regression analyses of potential moderators (which ones is not in the abstract).
Not in the abstract: the training protocols, their length and intensity, baseline VO2max, ages, each sex's own mean change and SD of change, whether any study had a non-training control arm, the risk-of-bias assessment, and how intensity was matched (relative or absolute).
Funding and interests: the Crossref and PubMed records list the Natural Sciences and Engineering Research Council of Canada (RGPIN-2019-04833); conflicts of interest are not in the abstract. No device maker, data platform or federation appears in the record.
Correspondence: Senefeld JW, Smith JR, Wiggins CC, Joyner MJ. Comment on "Sex dimorphism of VO2max trainability". Sports Med 2020;50(5):1047-1048, DOI 10.1007/s40279-020-01270-3; reply by Diaz-Canestro and Montero, Sports Med 2020;50(5):1049-1050, DOI 10.1007/s40279-020-01271-2 (titles and authors from Crossref; neither read).

Key Results

Outcome (men minus women, response to the same endurance-training dose)Mean difference (95% CI)PHeterogeneity
Absolute VO2max+191 mL/min (99 to 283)< 0.001I² = 0%
Relative VO2max+1.95 mL/kg/min (0.76 to 3.15)0.001I² = 0%
Heterogeneity: none detected among studies (I² = 0%, P ≥ 0.59).
Moderators: the meta-analytical results were "robust to potential moderating factors" (named only in the full text).
Not reported in the abstract: the mean gain in each sex, the percentage gains, the SD of individual change in either sex, and any non-training control.
Beside [REF-1243] (our arithmetic from that entry's raw changes): men minus women +0.12 L/min and +0.16 mL/kg/min with identical HIIT or sprint-interval protocols, neither significant. Only the L/min point estimate leans the same way (REF-1243's standardised absolute effects were 0.56 in women and 0.51 in men); the relative differences differ more than tenfold.

Mechanisms

Measured: larger absolute and relative VO2max gains in men than in women given a sex-matched dose of endurance training.
Authors' interpretation: the pooled evidence suggests "the presence of sexual dimorphism in the trainability of aerobic capacity"; the physiological explanation is not given in the abstract.
Inference: part of the absolute difference is body size: men start with a higher VO2max in L/min, and at the same relative intensity they train at a higher absolute power; the relative (mL/kg/min) difference is the comparison that bears on an individual.
Inference: 1.95 mL/kg/min is about half a MET (our arithmetic, 1 MET = 3.5 mL/kg/min). It is a group-mean difference among untrained adults; it says nothing about how much any one woman or man will gain, and individual changes scatter widely around the mean, largely from test noise and day-to-day variation (REF-1274, REF-498).

Practical Application

Do women gain less VO2max from training than men? With endurance training, untrained men gained ~2 mL/kg/min more than women in 8 small studies; with identical interval protocols, women and men gained alike (REF-1243).
Do not lower a woman's expected gain on this alone: the difference is a mean among untrained adults on endurance training (A-, from the abstract), the larger interval-training meta-analysis found none (REF-1243, A-), and neither studied trained women. Not from this paper; the base's own practice: give the same relative forecast to both sexes and let the athlete's own retests replace it.
Absolute numbers differ by size: if comparing a woman's gain in L/min with a man's, expect hers to be smaller (men +191 mL/min more here; +0.12 L/min more in REF-1243, not significant); compare in mL/kg/min or per cent.
Scope: untrained, healthy adults; no trained women, masters athletes, hormonal status or menstrual phase in the abstract.

Limitations

Read from the abstract only; the included studies, their protocols, durations, intensities, ages and risk of bias could not be checked.
Eight studies, 175 people (about 22 per study, our arithmetic); a small pool for a sex difference, whatever its I².
The sex comparison is observational within each study: men and women differ in more than sex (body size, baseline fitness, training history).
Untrained adults only; the authors' title claim of "sex dimorphism of VO2max trainability" is not tested in trained athletes.
A published comment (Senefeld, Smith, Wiggins and Joyner, 2020) and the authors' reply exist; their content was not read, so any methodological objection is not reflected here.
Funding: NSERC per the Crossref and PubMed records; conflicts of interest not in the abstract.
How this entry was checked and changed
Why this level

a meta-analysis of mostly small studies (about 22 people each, our arithmetic), the rubric's A- line; from the abstract (the full text is not open). Held at A- and not higher: the sex comparison is observational within each study (sex cannot be randomised), the abstract gives neither the training protocols nor each sex's own gain, a published comment by Senefeld et al. and the authors' reply (Sports Med 2020) were not read, and a larger meta-analysis of interval training found no sex difference (REF-1243, 19 trials for VO2max)