Does it matter whether lifting happens early in the day or after work? This guide reads three PubMed abstracts on 5 November 2026: a 2019 systematic review and meta-analysis of 11 studies (Grgic and colleagues), a 2016 trial in 42 young men (Küüsmaa and colleagues) and a 2008 trial in 27 men (Sedliak and colleagues). Full texts were not used, so details beyond the abstracts are not covered. The abstracts say nothing about particular equipment, and this guide makes no claim about dumbbells or kettlebells. General information, not training advice.
What the 2019 review reports
The review searched PubMed/MEDLINE, Scopus and SPORTDiscus. It included studies that examined time of day-specific resistance training while equating other training variables, such as training frequency and volume, between the groups. Eleven studies of moderate and good methodological quality were included. The abstract lists five main findings:
- at baseline, strength differs between morning and evening, with greater strength in the evening hours;
- resistance training in the morning hours may increase strength assessed in the morning to similar levels as strength assessed in the evening;
- training in the evening hours maintains the general difference across the day, with greater strength in the evening;
- comparing groups that trained in the morning with groups that trained in the evening, increases in strength are similar in both, whichever time of day strength is assessed;
- increases in muscle size are similar irrespective of the time of day at which the training is performed.
In plain terms, the review found that people tested stronger in the evening before any training, and that the strength and size gains from training were similar for the two training times.
A 24-week trial: more muscle in the evening groups after week 12
Küüsmaa and colleagues (Applied Physiology, Nutrition, and Metabolism, 2016) studied 24 weeks of same-session combined strength and endurance training, not lifting alone. Forty-two young men were matched and assigned to four groups: morning or evening, each with strength before endurance or endurance before strength (groups of 9, 9, 12 and 12).
- Strength: all groups similarly increased their leg press one-repetition maximum, by 14% to 19% when tested in the morning and 18% to 24% when tested in the evening.
- Muscle size: the cross-sectional area of the vastus lateralis (a thigh muscle) increased in all groups by week 24, by 12% to 20%. During weeks 13 to 24, the evening groups gained more muscle mass.
- Hormones: daily rhythms in testosterone and cortisol remained statistically unaltered by the training order or time.
The authors conclude that combined strength and endurance training in the evening may lead to larger gains in muscle mass, and that training order and time seem to influence the magnitude of adaptations only when the training period exceeded 12 weeks.
A 10-week trial: the morning-to-evening strength gap narrowed
Sedliak and colleagues (Journal of Sports Sciences, 2008) first put participants through 10 weeks of preparatory training at 17:00 to 19:00. They then randomised 27 participants into a morning group (07:00 to 09:00, 14 participants) or an evening group (17:00 to 19:00, 13 participants) for another 10 weeks. A matched control group of 7 participants did not train.
The main finding was that a significant difference in peak torque between the 07:00 and 17:00 tests decreased after time-of-day-specific training in the morning group, but not in the evening or control groups. The abstract adds that the extent of this adaptation varied between individuals. Electromyography (a measure of muscle electrical activity) during a maximal contraction did not show a time-of-day-specific adaptation, which the authors take to suggest that peripheral rather than neural adaptations are the main source of temporal specificity in strength training. This trial reported strength and electromyography, not muscle size.
Why the three abstracts do not give one rule
- Different training: the 2016 trial combined strength and endurance work in one session; the review concerns resistance training.
- Different outcomes: the review found similar muscle-size gains for the two training times, while the 2016 trial reports larger gains in the evening groups during weeks 13 to 24. The abstracts do not say whether that trial is among the 11 studies, and they do not explain the difference, so the two results are reported side by side, not merged.
- Different questions: the 2008 trial asked whether the morning-to-evening gap in strength changes with training time; it did not measure muscle size.
- Participants: both trials enrolled men. The review abstract does not describe its participants.
What the abstracts do not say
None of the three abstracts reports on sleep, work schedules, how long a session lasted, or which exercises were used, beyond the leg press and half-squat tests named above. The review abstract does not name a best time of day, and the two trial abstracts do not claim that their results would apply to every lifter. Nothing in them mentions women, older adults or equipment choice.
The bottom line
The 2019 meta-analysis of 11 studies reports that strength was greater in the evening at baseline and that increases in strength and in muscle size were similar whether training took place in the morning or the evening. A 24-week trial in 42 young men doing combined strength and endurance sessions reported similar strength gains and larger muscle gains in the evening groups during weeks 13 to 24. A 10-week trial in 27 men reported that the morning-to-evening gap in peak torque narrowed in the group that trained in the morning. The abstracts differ in design and outcome, are not combined into one rule here, and the figures come from abstracts only.
Sources
- The effects of time of day-specific resistance training on adaptations in skeletal muscle hypertrophy and muscle strength: a systematic review and meta-analysis, Grgic and colleagues, Chronobiology International, 2019 (abstract, PubMed), read 5 November 2026 (pubmed.ncbi.nlm.nih.gov)
- Effects of morning versus evening combined strength and endurance training on physical performance, muscle hypertrophy, and serum hormone concentrations, Küüsmaa and colleagues, Applied Physiology, Nutrition, and Metabolism, 2016 (abstract, PubMed), read 5 November 2026 (pubmed.ncbi.nlm.nih.gov)
- Effect of time-of-day-specific strength training on maximum strength and EMG activity of the leg extensors in men, Sedliak and colleagues, Journal of Sports Sciences, 2008 (abstract, PubMed), read 5 November 2026 (pubmed.ncbi.nlm.nih.gov)
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