The effects of time of day-specific resistance training on adaptations in skeletal muscle hypertrophy and muscle strength: A systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of controlled trials
PubMed 30704301 · doi:10.1080/07420528.2019.1567524
What was done
The authors performed a PRISMA-compliant systematic review and random-effects meta-analysis of studies indexed in PubMed/MEDLINE, Scopus, and SPORTDiscus. Studies comparing morning versus evening resistance training with equated training frequency and volume on muscle strength and/or hypertrophy were included. Study quality was evaluated using the Downs and Black checklist. Meta-analyses assessed baseline diurnal strength differences, within-group post-intervention strength by time of testing, between-group strength gains, and muscle hypertrophy.
What was found
Eleven studies of moderate and good methodological quality met inclusion criteria. The abstract reports no numerical effect sizes or confidence intervals. It reports that baseline strength was significantly greater in the evening than in the morning. Morning training brought morning-assessed strength up to levels similar to evening strength, whereas evening training preserved higher evening performance. Overall between-group increases in strength and muscle hypertrophy were similar regardless of whether training was conducted in the morning or evening.
Why it matters
This review suggests that long-term adaptations in muscle mass and strength are comparable whether resistance exercise is performed early or late in the day, allowing flexible scheduling.
Limits
The abstract does not report numerical effect sizes, confidence intervals, total participant count, participant characteristics (such as sex, age, or training status), or training program durations.
Cited by
- supports Transitioning resistance training from the late afternoon or evening to the morning causes an initial drop in performance that resolves within a couple of weeks.