Training a lift on more days a week did not clearly add strength, and with weekly volume equated it showed no difference: across 74 training groups from 12 studies, higher versus lower frequency gave a non-significant effect size of 0.09 (95% CI −0.06 to 0.24; p = 0.25), and volume-equated 1 day versus 3 or more days a week gave 0.03 (−0.20 to 0.27; p = 0.78); only upper-body lifts gained more at 3 or more days than at 1 (0.48, 0.20 to 0.76), a comparison the abstract does not describe as volume-equated, while lower-body lifts showed no significant difference between 3 or more days and 1 day (p = 0.22)
Ralston and colleagues pooled studies of how many days a week resistance training is done and asked whether more days build more strength. They set three bands, low (1 day a week), medium (2 days) and high (3 or more days), and pooled 74 treatment groups from 12 studies with a random-effects model.
Across combined multi-joint and isolation exercises, higher frequency leaned ahead of lower but not significantly. When weekly volume was the same, gains at 1 day and at 3 or more days did not differ (effect size 0.03).
Upper-body lifts gained more at 3 or more days than at 1 day; 2 days against 1 showed no clear difference for the upper body, and the lower body showed no significant difference between 3 or more days and 1 day. A medium-versus-high contrast leaned one way without reaching significance.
The authors conclude that, in a mixed population, the data do not tie more weekly days strongly to larger strength gains, that frequency had no significant effect once volume was equated, and that more studies are needed.
Participants
74 treatment groups from 12 studies; a "mixed population group" (the authors' term), with an untrained-only analysis named in the methods. Not in the abstract and not in the PubMed indexing (the record has no MeSH headings): sex, age, total number of participants and training levels.
Protocol
Key Results
| Comparison | Effect size (95% CI); p |
|---|---|
| Higher vs lower frequency, multi-joint and isolation combined | 0.09 (−0.06 to 0.24); p = 0.25 |
| 1 day vs 3+ days a week, volume equated | 0.03 (−0.20 to 0.27); p = 0.78 |
| Upper body, 3+ days vs 1 day | 0.48 (0.20 to 0.76); p < 0.01 |
| Upper body, 2 days vs 1 day | 0.12 (−0.22 to 0.47); p = 0.48 |
| Lower body, 3+ days vs 1 day | 0.21 as printed (−0.55 to 0.13); p = 0.22 |
| 2 days vs 3+ days (body region not named in this sentence) | 0.41 (−0.26 to 1.09); p = 0.23 |
Practical Application
Limitations
How this entry was checked and changed
risk of bias not read (abstract only): the abstract reports no risk-of-bias or quality assessment and gives neither the heterogeneity values nor what the funnel plots showed; 12 studies, with wide intervals in the body-region comparisons