For the past year, I have been religiously going to the gym and exercising. It has been a wonderful way for me to relieve some stress and not turn into a walrus. But, for a while, I was working out alone. One day, a fellow graduate student made the first move and invited me to workout with him. Since then “the gains” have become much more noticeable.

The other day, it occurred to both of us that there is an interesting game theoretic mechanism happening when exercising with a partner. At the end of a ridiculous “high intensity interval training” workout (HIIT), we tiredly discussed that the optimal Nash equilibrium would have been to cooperate and only do two rounds of the HIIT workout. But, we each defected and slid into the sub-optimal Nash equilibrium and pushed through all four rounds.

Economics of Workout Partners

The photo evidence of the sub-optimal Nash equilibrium

This is an example of the classic “Prisoner’s dilemma” game but we’ll call it the “Workout Partner dilemma”. In this game you have a pair of workout partners, Kevin and Greg. Both Kevin and Greg engage in friendly competition and want to outdo each other when they workout together. At the very least, they want to do the same amount of exercise repetitions, even if the weights are different.

However, being human, they both want to do what satisfies them the most, which is and always will be: cheating the workout. Halfway through the workout, the vast majority of humans want to call it quits. It is a natural human defense mechanism. Your mind starts to persuade you by rambling, “What in the hell are you doing this for? C’mon, let’s stop. You already broke a sweat! You can tell everyone on Instagram you went to the gym! That counts! Aren’t you hungry? Don’t you have work to catch up on? These next sets are not even worth it. What difference will it REALLY make if you call it quits. Just walk home really fast and that can be part of the workout! C’mon, let’s go!”

But, when you add someone else to the mix there is more pressure to not give in to our own desires. Competition also naturally emerges. Interpersonal competition between workout partners often overpowers our own human satisfactions and makes us work harder. A big part of the competition is never showing signs of weakness.

In this game, if we cooperate and simultaneously decide to not stress our bodies our too much and cheat the workout, we can reach the optimal strategy. But, because Greg and I aren’t at the point of finishing each other’s sentences (yet), if we were to cheat, one of us would have to take the hit and suggest we cheat first. Let me just tell you, that won’t be me. Furthermore, it hasn’t been Greg either.

Workout Partner Dilemma Greg Cheats Greg Starts, Commits, Finishes
Kevin Cheats 10,10 -5, 12
Kevin Starts, Commits, Finishes 12, -5 7, 7

For example, if I were to tell Greg that I think we should skip out on the last two rounds of the HIIT, I would be the one that gets viewed as the weakest link, which would negatively affect my self-esteem. Greg, on the other hand, would feel relieved because not only did he want to cheat (because it’s the optimal decision) but because he was not the one to suggest we cheat. Therefore, he can go on as the stronger one of the two, boasting a high level of self-esteem.

Start, Commit, and Finish

This table is not subject to time. This table reflects in-the-moment decision making, which for most of us, we would opt for being lazy. However, not cheating in workouts is always the best option, especially if you want to lose weight and reach overall optimality in the long run. But, after a workout in which you do not cheat, the recovery is a bit longer, which can sometimes be unpleasant.

The moral of the story here is that working out with a partner will indeed make you exercise harder, per economic game theory. Particularly, if you find a workout partner that you can easily find yourself engaging in friendly competition with. Importantly, a workout partner can help us Start, Commit, and Finish.

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