The simple piece of information that could dramatically increase your muscular endurance

How most of us choose to behave is shaped powerfully by the behaviour of others (or, more specifically, our perception of their behaviour). Psychologists call this the influence of “social norms”, and its potency has been investigated extensively in the context of environmentally friendly behaviours like recycling, and health behaviours, such as binge drinking and frequency of exercise.

What if this same psychological lever could be exploited, not to encourage people to take up more physical activity, but to boost their athletic performance? A pair of researchers, Carly Priebe and Kevin Spink, have tested this idea for the first time.

Sixty-eight regulars (nine men) at a pilates studio were asked to perform two plank exercises, and to hold each for as long as they possibly could. As a cover story, they were told that the purpose of the challenge was to help find out the average performance level for this exercise.

The plank is a physically demanding exercise that involves adopting a face-down prone position, then raising the body on forearms and toes, and holding this position rigid, parallel to the ground. It was emphasised to participants that they should hold the the position for as long as possible on both attempts, and that their times would be averaged for the research.

The participants were given a three-minute rest between each attempt. The key intervention is that between planks, half the participants were given the “social norms” message that 80 per cent of people similar to them (in terms of age, gender and pilates level) had achieved a 20 per cent longer time on their second effort. The other participants were told nothing of this kind, or anything else (this is a potential weakness of the study, which I’ll return to).

The researchers had hoped their intervention, if successful, would lead merely to sustained performance on the second attempt. The rather dramatic result is that participants given the social norms message achieved a five per cent increase on their second attempt (first attempt average time was 95.82 seconds; second attempt average was 99.79 seconds). This is dramatic because after performing a first plank to exhaustion, one would typically expect participants’ second attempt to be shorter. The control participants, as expected, achieved a significantly shorter time on their second plank attempt (76.38 seconds vs. 90.09 seconds on their first attempt – a drop of 18 per cent).

Priebe and Spink said their findings “hint at the potency of the descriptive norm information and the potential effects of social influence on physical activity tasks.” Participants in the social norms condition reported higher “self-efficacy” (belief in their own ability) than control participants, so this hints at a possible mechanism for the effect of the intervention.

A strength of this research is that the researchers gauged participants’ beliefs about other people’s performance before presenting them with the social norms message. The majority of participants assumed that most others would decline in performance on their second attempt. This was important to check because past research has shown that social norms interventions can backfire if people hold initial beliefs that exceed the reality of the normative message.

As hinted at earlier, a weakness of the study is the lack of a control condition that communicated a different message to the participants. This means we can’t tell how much of the apparent effect of the current intervention was specific to its social norms content. It’s possible receiving any kind of motivational message between exercises would have had a galvanising effect. Another problem, of course, is that the social norms message was a fabrication – the participants were effectively fed a lie. It’s also not clear how long this kind of intervention could sustain its effects. News of other people’s performance might be motivating at first, but could quickly lose its potency, or even become counter-productive.


Priebe, C., Spink, K. (2014). Blood, sweat, and the influence of others: The effect of descriptive norms on muscular endurance and task self-efficacy Psychology of Sport and Exercise, 15 (5), 491-497 DOI: 10.1016/j.psychsport.2014.04.012

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

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