Is hiring a personal trainer worth it?

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Hiring someone to tell you what exercises to do seems like a reasonable proposition — after all, there’s a big difference between a well-planned exercise program and just puttering around the gym. But what about after you’ve learned the details of the program: is it still worth paying someone to come and watch you work out?

According to a new study in the Journal of Strength and Conditioning Research, yes. (And yes, I’m aware that JSCR is the official organ of the National Strength and Conditioning Association, which may have a vested interest in promoting this idea.)

The study, by researchers at the University of Brasilia in Brazil, builds on previous studies that have found that people doing weight training build more muscle and gain more strength when they’re supervised than when they’re on their own. In this case, the study compared 124 untrained young men, and had them undertake an 11-week training program with either a coach for every five athletes or a coach for every 25 athletes. Sure enough, the more highly supervised athletes gained significantly more strength in bench press and knee extensor exercises.

As the paper explains, personal trainers “may help to control important training variables such as load, rest intervals, and exercise technique and to provide motivation and psychological reinforcement,” so it’s hard to nail down exactly what’s happening. But the data provide some interesting insights.

One initially confusing fact is that the total volume of weight lifted was pretty much the same between the two groups. On closer examination, what happens is that the less-supervised group picks a slightly lighter weight and lifts three sets in a nice, controlled manner. The heavily supervised group picks a more ambitious target, reaches failure during the third set, and has to stop a few reps earlier. Total volume is the same, but the guys reaching failure get bigger training benefits.

I certainly don’t discount the effect of knowledge and supervision (e.g. to ensure correct form, especially in inexperienced exercisers), but my interpretation is that motivation is the key differentiator between the two groups. I think most people would agree intuitively that personal trainers can help people push harder than they would otherwise. But for those who can’t or don’t want to spring the cash, it seems to me that a good training partner can help serve a similar role — especially if you’re close to the same abilities, and you don’t want to have to re-rack the weights between each set!