One Reason Your Friend Might Be Getting Fitter Faster

Sometimes it can feel like no matter how much you lift or how far you run, you just don’t get any stronger or faster. Meanwhile, your workout buddy — who is following precisely the same training regimen as you — seems to be evolving into an elite marathoner or packing on muscle like an 18-year-old football prodigy. So what gives?

Genetics can certainly play a role — some people are simply predisposed to gain more muscle or build more speed and endurance than others. But exacerbating the issue might be something far more basic: You’re simply not doing the right workouts for your body type. That’s the conclusion an international team of scientists recently reached after studying two very special groups of rats. One group was genetically engineered to respond robustly to aerobic exercise, while the other group was bred to be “non-responders.”

The outcome was exactly what you’d expect from such genetic tinkering: The “born-athlete” rats increased the distance they could run before tiring by 40 percent, while the other group improved just two percent. But according to the researchers, the implications of their study go beyond the idea that athleticism is simply written into some people’s genes. Indeed, the results might have been quite different if the rats’ tiny running wheels were swapped for wee squat racks, according to Dr. Ulrik Wisloff, the study’s lead author and the director of the K. G. Jebsen Center of Exercise in Medicine at the Norwegian University of Science and Technology. Wisloff’s message: The genes that control the body’s response to aerobic exercise are likely different than those that regulate its response to strength training, so if your workout isn’t working, try something different.

That’s not to say that if powerlifting doesn’t work for you, you must be a runner (or vice versa). Rather, your fitness sweet spot might simply lie in a different part of the athletic spectrum than the one in which you currently train. Mix it up, embrace different forms of exercise, and see what sticks.