Running on plenty

It’s difficult to study endorphin production directly, however, since much of the action takes place within the working brain and requires a lumbar puncture to monitor, says Dr Dunbar. Few volunteers would willingly undergo such a procedure, and certainly not in a study about laughing. So instead, he and his colleagues turned to pain thresholds, an indirect but generally accepted marker of endorphin production. If someone’s pain threshold rises, one can surmise that they are awash with the natural analgesics.

In Dr Dunbar’s experiments, pain thresholds did go up after people watched the funny videos, but not after they viewed the factual documentaries.

The only difference between the two experiences was that, in one, people laughed, a physical reaction that the scientists quantified with audio monitors. They could hear their volunteers belly-laughing. Their abdominal muscles were contracting. Their endorphin levels were increasing in response, and both their pain thresholds and their general sense of amiable enjoyment were on the rise.

Why the interplay of endorphins and laughing should be of interest to those of us who exercise may not be immediately obvious. But, as Dr Dunbar points out, what happens during one type of physical exertion probably happens in others. Laughter is an intensely infectious activity. In this study, people laughed more readily and lustily when they watched the comic videos as a group than when they watched them individually, and their pain thresholds, concomitantly, rose higher after group viewing.

Something similar may happen when people exercise together, says Dr Dunbar. In an experiment in 2009, he and his colleagues studied a group of elite Oxford rowers, asking them to work out either on isolated rowing machines, separated from one another in a gym, or on a machine that simulated full, synchronised crew rowing. In that case, the rowers were exerting themselves in synchrony, as a united group.

After they exercised together, the rowers’ pain thresholds – and presumably their endorphin levels – were significantly higher than they had been at the start, but also higher than when they rowed alone.

So if you typically run or bike alone, perhaps consider finding a partner. Your endorphin response might rise and, at least theoretically, render that unpleasant final hill a bit less daunting. Or, if you prefer exercising alone, perhaps occasionally entertain yourself with a good joke.

Gretchen Reynolds, New York Times