Even though the players got stronger, their ability to jump higher or more powerfully didn’t improve after five weeks of leg press training — meaning strength on the machine doesn’t automatically make you jump better.

Doing leg press exercises twice a week for five weeks makes teenage rugby players much stronger when pushing with both legs at once, whether they use one leg or both legs at a time.

Even though the players got stronger from doing leg presses, they didn’t run any faster after five weeks — meaning just getting stronger on a machine doesn’t automatically make you sprint better.

When teenage rugby players train one leg at a time on the leg press machine, they get much stronger in that single leg than when they train both legs together at the same time.

Training one leg at a time makes that leg much stronger than training both legs together — even though both methods make you equally strong when using both legs at once.

Both training methods made athletes jump higher and turn faster, but didn’t make them run straight-line sprints any faster.