You may want to share this study with workout buddies, as it gives a deeper explanation as to why working out with another person can boost performance.

Research shows that the presence of a spotter during bench press training is enough to improve training performance by reducing perceived exertion and enhancing feelings of self-efficacy. Leeds Beckett University researchers from the Centre for Human Performance in Leeds, England, conducted the study to better understand why exercisers perform better in the presence of personal trainers, coaches or training partners.

Investigators recruited 12 recreationally trained, injury-free young men with at least 12 months of weight training experience. Subjects participated in three bench press training sessions. The first session was to establish their one-repetition maximum. The second and third sessions required subjects to bench-press three sets to failure at 60% of 1-RM with 2 minutes of rest between sets.

In the second session, two spotters were present—one on each side of the bar. In the third, spotters were there but remained hidden from participants.

Subjects were not informed of the trial’s purpose and received the same verbal instructions in the second and third sessions—in essence, to maintain focus on the bar and to lift to failure. Researchers recorded total repetitions, total weight lifted, and ratings of perceived exertion and self-efficacy in the second and third sessions.

Data analysis showed that total reps and weight lifted were significantly greater—about 11% better—when visible spotters were present. Eleven of 12 participants performed better under this condition. For the one who didn’t, performance was identical in both conditions. With spotters, subjects also reported lower exertion levels and higher self-efficacy ratings.

Study authors believe that the presence of others during training influences emotions and behavior. Since these participants had weightlifting experience, they likely felt motivated to be seen as competent, leading them to exert greater effort and lift more weight when spotters were watching. Moreover, the presence of others helped make the extra effort feel easier. The researchers also think the presence of spotters who observe without interfering supports weightlifters’ confidence in their ability to continue.

To apply these study findings when working out with another person, you should stay in close proximity and ideally serve as a spotter when someone is performing resistance exercises, according to the authors. A spotter’s presence is not only for safety and program design but also to increase performance by boosting self-efficacy and lessening feelings of effort.

Find the study in The Journal of Strength and Conditioning Research (2019; 1755–61).