The Twin Study: What’s the Real Value of Exercise?

If you exercise regularly you will be healthier. Isn’t that right?

That’s what we’ve learned over the years. Study after study has shown that exercise promotes healthy hearts, muscles, bones, and even brains.

But, there are a few glitches in many of these studies: Study results often rely on interviews and questionnaires that measure perceived changes in the participants’ physical and mental health. How accurately can a participant interpret how they feel AND, can they really remember how they “used to feel” as a point of comparison?

All of the studies involve people who have different genetic makeups, different upbringings, and different environmental factors that affect their day-to-day lives. Can scientists really draw definitive conclusions from studies that have so many uncontrollable factors?

The Study of 10 Identical Twins

One way to get more precise research results about the positive effects of exercise is to study identical twins. This can eliminate many confounding variables since these subjects have identical DNA and often have a very similar personal history.

That’s exactly what a group of Finnish researchers from University of Jyvaskyla decided to do. Searching through their database of identical twins, they found 10 pairs who had been participating in research since the age of 16. These twins were very similar in many regards including their upbringing, education, career paths, and even food choices. They did however differ in one major way: One twin exercised regularly while the other did not exercise much at all.

How Did the Twins Compare?

Not surprisingly, the twin who exercised regularly showed a number of physical health characteristics that the sedentary twin did not display:

  • Lower body fat
  • Higher cardiovascular endurance levels
  • Faster metabolism
  • Greater muscle mass 

There was also strong evidence that exercise does lead to improved brain functioning. The physically active twins had more grey matter, particularly in the parts of the central nervous system responsible for coordination and motor control. In other words, these twins have brains that are more deeply “connected” to their body.

Key Takeaways

While it’s always going to be difficult to conduct fool-proof research, this particular study using only identical twins does eliminate many of the typical flaws that can impact findings. The researchers concluded that exercise does lead to improved fitness (duh!) AND that it likely contributes to a lesser likelihood of developing Type 2 Diabetes.

twins exercise

Exercise is great, but this might not be the best way to drag your twin to the gym!

What About Exercise and Weight-Management?

The twin study did show that regular exercise reduces body fat, and this is a result that has been confirmed in many other studies. One supporting piece of research specifically aimed to determine the effects of resistance training on a person’s ability to lose weight. Here’s how this one worked:

  • The researches conducted 13 studies between 1990 and 2007
  • Each study included 17 to 120 randomized participants
  • The average age of the participants was 47 years old
  • Each study included a Resistance Training (RT) group that performed three 30-minute sessions of training per week for 8 weeks
  • The studies also included a Control Group (CG) for comparison (these participants did no exercise)

Did 90 Minutes of Weekly Exercise Make a Difference?

After 8 weeks the the RT and CG participants were evaluated for any body changes. The researchers found that the RT group shed an average of 6lbs of fat while the control group maintained their starting body composition or gained slightly.

What Does This Mean For You?

All of this research paints a very optimistic picture.

1. Your Heredity Is Not Your Destiny

Just like the identical twins who chose an active lifestyle, you can make tremendous positive changes to your physical and mental health simply by moving your body. Your DNA cannot stop you!

Check out Cassandra and Kelsey, identical twins who asked about this exact question:

2. It Doesn’t Take Much

The #1 reason why people say they don’t exercise is a “lack of time” – this is simply an excuse. Just look back at the second research study…those participants exercised for a total of 90 minutes per week! That’s all.

Planning a quick walk at lunch, a trip to the gym with a friend, or a basic workout at home when you have a few minutes. It does not have to be much – A little is so much better than nothing (and the twins proved it!)


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