Cheerful news for slothful theatregoers: watching from the stalls can stimulate your cardiovascular system as much as half-an-hour of exercise.
Researchers from UCL and the University of Lancaster – commissioned by Encore Tickets – wired up audiences watching the musical Dreamgirls. They found changes in their subjects’ heart rate during emotional and energetic moments on stage equivalent to that of professional tennis players during a long rally .
It’s easy to dismiss this as silly publicity-hungry pop science. But actually, beyond the stuff about tennis pros it does serve as a reminder of how little we consider the physical impact of theatre on its audiences (moaning about uncomfy seats aside).
It is usually considered a good sign if a show makes you well up or split your sides. But for critics there’s an expectation of greater detachment, of cool analysis, and there can be a reluctance to express responses in any way but cerebrally.
As Matt Trueman has suggested elsewhere, the self-consciousness of the critic can get in the way of laughter. But it surely can’t be good for the body (or soul) to be keeping a lid on it, holding back those responses night after night.
We just don’t write that much about theatre and its impact on our bodies. Maybe this is a British thing too, a fear of exposing ourselves through showing extremes of emotion (I’ve often stealthily wiped tears away with a sleeve rather than had a proper bawl).
Which seems a shame – surely the signals your body gives, overriding the analytical calm of the mind, are a sign of a production working on a particularly powerful level?
Naturally there are famous exceptions. Noises Off had even critics rolling in the aisles and War Horse had battle-weary reviewers reaching for their hankies. But generally there seems to be a slight reticence, as if it isn’t quite appropriate to let yourself go if you’ve got a notebook in your lap.
But why should it be seen as faintly embarrassing to feel faint at Cleansed  or to need a little sit down after The Ferryman  because it left you breathless and shaky? The times I’ve most been powerfully affected by theatre, the elation wasn’t only my brain going ‘that was very clever and well done’, it was also, yes, my heart racing as if I’d just been on an endorphin-releasing run.
Of course, such reactions can be due to the emotional baggage we carry into the theatre. There’s a reason why occasions of crying during the Edinburgh Fringe are about 1,000% higher than normal, and it’s to do with exhaustion, the intensity of seeing five shows a day, and hangovers. And I’m sure most critics recognise when a show is pressing personal buttons.
But then, this intense identification, the ability to consider our own lives in relation to fictional ones unfolding in front of us, can also be a strength. As pointed out in recent reviews of the sniffle-inducing Follies , we’re not always sure we feel pity for the characters’ lost pasts, or our own.
Theatre can be a release valve, a communal act of catharsis. Trying to leave after a performance of Yerma  this summer involved clambering past broken, sobbing 30-something women; it hadn’t so much struck a chord as smashed up the whole piano.
Of course, a good critic will unpack why a show has this impact – how the juxtaposition of that song and that scene gives you full-body goosebumps – and will make some value judgement as to whether it’s cheap sentiment or core-shakingly profound.
But it seems daft to try to hold back such physiological reactions. They are, in their way, an instantaneous, involuntary review by the body, and surely a valuable, valid response. And besides, it turns out it’s a good workout.