A Lesson in Study Design (and the Bench Press)

If exercise is intense enough, the repeated bout effect is very real.

The whole point of hitting the gym is what is sometimes called super compensation. The act of breaking down the body is only useful if it comes back stronger than before, and if you time it just right, the super-compensation will compound itself. In a  Journal of Strength and Conditioning Research study, researchers examined just how quickly these changes occur.

In order to properly interpret the results of the study, it’s important to understand what is often called the repeated bout effect. If you’ve ever looked at research in exercise science, you’ll often see that many trials are of a randomized design. Studies are randomized in part to reduce the influence of the repeated bout effect. The results of studies that are not randomized could be explained solely from this effect, and may be worthless as a result.

For example, if one bench press protocol was discovered to be better than another, but was always performed after the other protocol, it could be that the participants had actually gotten stronger from the first one and not the bench press. However, if the experiment was evenly randomized, with none of the protocols being consistently first, then we eliminated the repeated bout effect.

But some might argue that the repeated bout effect takes time to sink in. We might guess that, say, a month might not be enough time to get a significant impact from the repeated bout effect. Few would guess that a single session could be enough, and that’s what the researchers in the Journal study wanted to know.

As in the made-up example above, the researchers used the bench press to test the repeated bout effect. They used eight experienced lifters and had them do four sets of eight eccentric-only reps at seventy percent of the each lifter’s max eccentric bench press. After this, each participant’s strength, soreness, and muscle damage were studied. Once that was done, the participants returned after two weeks and did it all over again.

The degree of the repeated bout effect was pretty surprising. After just one session and two weeks of rest, the decrement to strength following the eccentric protocol was fifty percent less than it was after the first session. The participants were much less susceptible to fatigue as a result. The rating scale used to assess muscle soreness determined the participants were less than half as sore the second time. And, in that trend, the blood markers used to assess muscle damage dropped by a little more than half.

The researchers concluded that if exercise is intense enough, the repeated bout effect is very real. It can occur after a single session, even when rest is long enough to return all the tested values back to baseline. So when you read studies, be sure to check that they are randomized before you interpret results.


1. Adilson Meneghel, et. al., “Muscle damage of resistance-trained men after two bouts of eccentric bench press exercise,Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0000000000000494

Leave a Comment