After just three weeks of short, intense bike or sprint workouts, older men between 63 and 72 got better at bouncing back from muscle tiredness caused by repeated hard exercise — their muscles...

When young and older men do short, super-intense bike or sprint workouts, the young guys get better at using oxygen during exercise, but the older guys don’t — their bodies just don’t respond the same way.

After just three weeks of short, intense bursts of running, older men had less of a biological marker in their blood that signals stress or damage in the body—this might mean their bodies are under less strain as they age.

Older men in their 60s and 70s didn’t get better at using oxygen during exercise after three weeks of intense sprinting, but younger men did—so aging might make it harder for your body to improve aerobic fitness from short, intense workouts.

When lifting weights and stopping 3 reps before failure, there is less reduction in muscle strength 24 hours later compared to lifting until complete exhaustion or stopping only 1 rep before failure.

When young male wrestlers do bench presses with only one minute of rest between sets, they experience more fatigue than when they rest for three minutes, suggesting that shorter breaks increase fatigue during resistance training.