Lifters hit the gym at all hours—some before work, others after, and other lucky folks have a more flexible schedule. But, is there an optimal time of day for training? A ton of research suggests that our body’s internal clock, or circadian rhythm, influences strength, endurance, and overall performance throughout the day.
One study by Guette et al had participants perform maximal strength tests at 6AM, 10AM, 2PM, 6PM, and 10PM. The results? Strength peaked in the evening, with participants performing best around 6PM. The authors suggested that this had to do with peripheral factors such as tympanic temperature. This aligns with broader research showing that physical performance is generally higher in the afternoon and early evening, roughly 6–12 hours after waking.
What about hypertrophy? In the 2010s, a research group in Finland conducted several studies on the topic (1, 2, 3). Broadly speaking, all three studies showed a benefit of training in the afternoon/evening versus training in the morning for muscle hypertrophy. Importantly, the difference may only be detectable in longer studies – while the first study in the series did find a slight benefit to training in the afternoon, the difference was not statistically significant. On the flip side, a later study, which lasted for a whopping 24 weeks, did find a statistically significantly greater amount of muscle growth in the afternoon training group compared to the morning training group.
There have been more studies on training time and muscle hypertrophy and strength, fortunately. A 2019 meta-analysis by Grgic et al examined all studies on training time and strength outcomes. Their findings showed that training time didn’t significantly impact muscle hypertrophy, with a standardized mean difference centered at exactly 0. However, strength gains were influenced – those who trained in the evening saw greater improvements when tested in the evening compared to those who trained in the morning.
When interpreting these findings, it’s worth keeping in mind that the relatively small benefit of training later in the day may simply not have shown up due to most studies being of a short-ish duration. However, since the difference in hypertrophy observed in the Grgic meta-analysis was centered around 0, I’m personally not sold on there being a benefit to training later in the day.
That’s not to say training time is entirely irrelevant if you’re not a competitor. A 2021 study by Blazer et al found that while objective performance metrics (e.g. bar speed) wasn’t greater, training based on preference – when lifters had a preference for training – enhanced both motivation and resulted in lower RPE/effort scores. So, while your performance may not change that much, it may make you feel more motivated and enjoy the session more to train at the right time for you.
So, should you shift your training schedule? If you’re a general lifter, consistency is king. Train whenever it fits your lifestyle. However, if you’re an athlete competing at a specific time of day, adjusting your workouts to match your competition schedule could offer an edge. Finally, if you really want to hedge all your bets, even if it’s unlikely to be a difference in muscle growth worth caring about, training in the afternoon – or around 6-12 hours after you wake, if you have an atypical chronotype – probably won’t hurt.
