The best hour to train is the one you’ll keep.

Researchers at the University of Basel measured when 108 adults aged 60 to 80 were strongest, then had them train either at their personal peak or at their personal low. After 12 weeks, both groups ended up in the same place: same strength, same grip, same muscle.

That’s one worry you can drop.

Your strength really does change through the day

Before any training began, each person’s daily strength rhythm was measured. Participants took strength tests at 8:00, 12:00, 16:00 and 20:00 on four separate days.

The rhythm was real. On the main strength test, people were about 10% stronger at their best hour than at their worst.

So the question wasn’t whether time of day affects performance. It does. The question was whether training at your strong hour pays off over weeks.

Training at your peak hour built no more strength or muscle

The 108 participants were randomly assigned to three groups:

  • Train at their personal peak time.
  • Train at their personal trough time.
  • No training (a control group).

The program ran for 12 weeks: two weeks of getting used to it, then ten weeks of progressive training. Each week had two supervised resistance sessions, with leg presses, chest presses, deadlifts, rows and squats, plus one 30-minute cycling session. From week three, people lifted to failure within 8 to 15 repetitions, with loads rising as they got stronger.

Both training groups attended more than 90% of sessions. Participants knew when they trained, but not whether that time was their peak or their trough.

The result:

  • 0.06 newtons per kilogram of body weight: the adjusted difference in main strength between the peak and trough groups. Close to zero, and well within chance.
  • Grip strength and arm and leg muscle mass showed the same picture.
  • Clock time didn’t matter either. Morning versus evening training showed no consistent pattern.

Performing better at 4 pm isn’t the same as adapting better

Being stronger in the afternoon than at 8 am is real. But that’s about a single session.

What counts over weeks is adaptation: whether your muscles grow and your strength rises in response to repeated training.

The trial suggests these are two different things. A better performance at one hour didn’t turn into better long-term gains. The key ingredient was simply doing the training, consistently and with enough effort.

Timing changes how one session goes. Showing up changes what twelve weeks do.

The hunt for the perfect hour can cost you workouts

Optimization advice can quietly turn into an obstacle.

If you believe there’s a right hour, it’s easy to put training off until you can do it “properly”, or to feel that a workout at the wrong time is half wasted.

For older adults doing regular strength training, this trial suggests that worry is unnecessary. The authors themselves conclude that flexible scheduling may help people keep training.

What the study can’t tell you

  • Participants were fairly healthy, active older adults. The results may not apply to frail older people, younger athletes or people training for other goals.
  • Each person’s peak was estimated from four days of tests, which may not capture their true rhythm. People training at the same hour every day may also adapt to it.
  • The effective training period was ten weeks. Small differences in muscle growth could take longer to appear.
  • It tested one kind of program. It doesn’t show that timing never matters, for anyone.
  • The peak group had more dropouts, mostly from musculoskeletal complaints, and only participants with complete data were analysed.
  • The advice below is a reasonable inference, not something the trial tested.

Train when you’ll actually show up

In this trial, showing up beat perfect timing.

Pick the slot in your week you can protect, and stop moving workouts around to chase a better hour.