Home training removes many scheduling limits, so the question of whether to train in the morning or the evening is a practical one. Two published reviews address it directly: a 2019 systematic review with meta-analysis of resistance training studies, and a 2012 review of training at a specific time of day. This article summarises what each reports and what the evidence does not settle. It covers general findings in healthy adults and is not advice for anyone with a health condition.
The 2019 systematic review and meta-analysis
Grgic, Lazinica, Garofolini, Schoenfeld, Saner and Mikulic searched PubMed/MEDLINE, Scopus and SPORTDiscus for studies of time-of-day-specific resistance training. To be included, a study had to equate other training variables, such as frequency and volume, between the groups, so that time of day was the difference being tested. Eleven studies of moderate and good methodological quality were included, assessed with the Downs and Black checklist.
The authors report five main findings:
- at baseline, strength is significantly greater in the evening than in the morning;
- training in the morning may raise strength measured in the morning to levels similar to those measured in the evening;
- training in the evening maintains the general difference across the day, with greater strength in the evening;
- when morning and evening training groups are compared, increases in strength are similar in both, whatever time of day the strength test is done;
- increases in muscle size are similar regardless of the time of day at which training is performed.
What the 2012 review adds
Chtourou and Souissi reviewed performance after training at a specific time of day. They report that the effect of time of day on aerobic performance appears to be equivocal, while for anaerobic exercise the effect is well established, with early-morning lows and peak performance in the late afternoon. Regular training in the morning may raise the lower morning performances to the same or even a higher level than the usual late-afternoon peak, through a greater increase in evening performance. Regular evening training may widen the morning-to-evening difference through a greater increase in late-afternoon performance. The authors conclude that adaptations to training are greater at the time of day at which training is regularly performed than at other times. They add that changes in resting hormone concentrations could explain the time-of-day-specific adaptations, but that precise information on the underlying mechanisms is lacking.
Putting the two reviews together
The two reviews describe a consistent picture. Performance tends to vary across the day, with lower values in the early morning and higher values later. The body appears to adapt to the time at which it is trained, which is why morning training narrows the gap. Yet the 2019 meta-analysis, which isolates time of day by equating other variables, finds similar gains in strength and similar increases in muscle size whichever time of day is used. The specificity effect therefore affects how strength presents at a given hour more than the total amount gained.
What this means for testing and tracking
One practical implication follows directly from the reported findings. Strength is measured higher in the evening than in the morning at baseline, and training at a given time raises performance at that time. Comparing a morning test with an evening test can therefore mix a genuine change in strength with a time-of-day difference. Tests of maximum lifts, and the loads used to set progression, are more informative when repeated at a consistent time. This is relevant to any schedule that uses one-repetition-maximum estimates, covered on this site in One-Rep Max Testing and Percentage-Based Training.
Limits of the evidence
- The 2019 review includes only 11 studies, so subgroup comparisons rest on small numbers.
- The 2012 review does not report a pooled analysis in its abstract and states that mechanisms are unknown.
- The reviews cover time-of-day effects on average, not individual chronotype. Neither abstract reports results for early-riser and late-riser groups separately.
- The findings concern strength and muscle size. They do not address other goals such as sleep, adherence or aerobic performance, for which the 2012 review notes that the evidence on time of day is equivocal.
Where equipment enters
These reviews say nothing about products. Their relevance to buying is indirect: a home setup that can be used at the same time every day, or at whichever time fits a household, makes it easier to hold training time constant. Choices that affect when a machine can be used, such as noise, are treated in articles on this site about treadmill noise and vibration in upstairs rooms.
Frequently asked questions
Is evening training better for strength?
The 2019 meta-analysis finds similar strength gains from morning and evening training. Strength is higher in the evening at baseline, but the gains from training do not differ between the two groups.
Does the time of day matter for muscle growth?
According to the same review, increases in muscle size are similar irrespective of when training is done.
The bottom line
Reviews of time-of-day training find that strength tends to be higher in the evening, that the body adapts to the time it is trained, and that morning and evening training deliver similar gains in strength and muscle size when other variables are equal. The best time is therefore the one that can be kept consistent, and tests are most comparable when repeated at the same hour. The evidence base is small and does not address individual differences.
Sources
- Grgic J, Lazinica B, Garofolini A, Schoenfeld BJ, Saner NJ, Mikulic P, “The effects of time of day-specific resistance training on adaptations in skeletal muscle hypertrophy and muscle strength: A systematic review and meta-analysis”, Chronobiology International, 2019
- Chtourou H, Souissi N, “The effect of training at a specific time of day: a review”, Journal of Strength and Conditioning Research, 2012