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Why Some People Get More Fit Than Others

You might have often been at the gym or in a fitness class wondering why you’re performing the same workout as the person next to you, but they seem to be “more fit.” Is it because they’ve been working out longer than you have? Is it because they have the help of a personal trainer? Or is it simply due to genetics? Scientists are weighing in with recent published research studies and are finding that your genes may have more impact on how your body responds to exercise than the way you’re exercising.

One study, published in March, examined the weight loss and aerobic trends of 95 overweight and obese older men and women, aged 65-79, over the course of five months. Each individual participated in aerobic training four days a week and resistance training three days a week. The researchers found that while the increased exercise improved physical function for most of the adults, the magnitude of improvement varied widely, leaving the answer open-ended as to why.

Another study, published in April in the Journal of the American College of Cardiology, studied two strains of rodents that either would or would not respond well to exercise. The scientists bred male and female rats who responded well to exercise together, and male and female rats who didn’t respond well so that they could truly see if genetics had a role in high or low responders to exercise.

After training the animals with programs that were identical in speed and intensity for two months, the researchers found that the rats that were bred to respond well to exercise increased their running distance before tiring by 40 percent, and the rats that were bred to be more resistant to training actually lost about two percent of their endurance.

Furthermore, the researchers examined the animals’ hearts as well. The high-responding rodents showed structural changes in heart cells that are associated with growth and strength – signs of an athletic heart. At the opposite end, the low-responding rodents had almost no change since they started exercising: their hearts hardly changed and were similar to those from animals that hadn’t run.

This is perhaps the most fascinating part of the research: scientists were able to differentiate the strength of the heart based on genetics, no matter how much exercise the animal engaged in.

Humans have these same genes in our hearts. While it’s difficult to tell if our genes respond in the same way as the animals’ genes did in the study, it’s important to recognize that we should pay more attention to how our bodies are responding to exercise. Even if you’ve been training for months and cannot run farther than you could before, perhaps you should change the intensity or the workout entirely.

How does your body respond to exercise? Share your stories with us on our Facebook page.