Will I get a better workout if I hire a personal trainer?
In a famous study at Ball State University in Indiana, researchers put two groups of 10 men through identical 12-week strength-training programs. The groups were evenly matched when they started, and they did the same combination of exercises, the same number of times, with the same amount of rest.
At the end of the experiment, one group had gained 32 per cent more upper-body strength and 47 per cent more lower-body strength than the other. No performance-enhancing pills were involved - the only difference was that the more successful group had a personal trainer watching over their workouts.
There are between 10,000 and 15,000 personal trainers in Canada, according to Can-Fit-Pro, an organization of fitness professionals that certifies 8,000 of them. Others are certified by groups such as the Canadian Society for Exercise Physiology and the U.S. National Strength and Conditioning Association.
A good trainer will help you assess your fitness goals, design a safe and effective program to meet those goals and motivate you to put in the necessary work.
But, as the Ball State study shows, there are other, less obvious ingredients that successful trainers provide - and a series of recent studies offer some hints about how we can tap into these benefits.
The crucial difference between the training of the two groups at Ball State was very simple: By the halfway point of the program, the supervised group was choosing to lift heavier weights. Since both groups started with the same motivation level, it was likely the trainer's presence leading that group to set more ambitious targets.
Other studies have consistently found that, left to their own devices, novice weightlifters tend to work out with weights that are less than 50 per cent of their one-repetition maximum, which is too low to stimulate significant gains in strength and muscle size.
Even more experienced strength trainers often fall into this trap, according to a 2008 study in the Journal of Strength and Conditioning Research.
Researchers at the College of New Jersey found that women used to training alone chose on average to use just 42 per cent of their one-rep max for a 10-repetition set. In contrast, women who had experience with trainers chose weights averaging 51 per cent of their one-rep max.
"Many times, there is initial fear," says Nicholas Ratamess, the study's lead author. "We also found that some women who did not have a personal trainer underestimated their own abilities because they did not routinely push themselves too far."
The latest attempt to address this question comes from researchers at the University of Brasilia in Brazil. They compared two groups of 100 volunteers who undertook a 12-week strength-training program, supervised either by one trainer for every five athletes, or one trainer for every 25 athletes.
The results, which will appear later this year in the Journal of Strength and Conditioning Research, display a familiar pattern. The highly supervised group improved their bench press by 16 per cent, while the less supervised group chose lighter weights and improved by only 10 per cent.
In one sense, this is yet another argument for getting a personal trainer if you can afford one. But the differences here are more subtle, since both groups had access to a trainer who could provide guidance on proper form and choosing appropriate weights. Instead, motivation and the willingness to tackle ambitious goals seem to be the differentiating factors.
As Dr. Ratamess points out, these are the kinds of benefits that an enthusiastic training partner can also provide. For less experienced exercisers, the educational role of the personal trainer takes on greater importance, he says. But beyond that, simply having someone there watching you - whether it's a personal trainer or a workout partner - seems to confer an additional benefit.
Certainly, he says, "both have advantages compared to training independently."
Alex Hutchinson blogs about research on exercise at sweatscience.com.