Individual differences. What science prefers to be silent about

The idea for this article came up last year when we gave talks in the UK at the Personal Trainers Collective Conference with Brad Schonfield and Alan Aragon. Then we shoveled a ton of research into linking genetic differences to fitness potential, but found relatively little data on individual differences.

James’ presentation was replete with graphs showing differences in individual results, suggesting perhaps the most important aspect of science that has been little reported. We hope that over time it will become standard practice to report individual data, but at the same time we want to show you that research usually only reports averages that may not apply to you.

Consider the following situations:

  • Your friend swears she’s doing high-intensity interval training (HIIT) to reduce body fat. In addition to increasing calorie expenditure from exercise, she notices an overall boost of energy throughout the day, which she claims will allow her to burn even more calories. However, every time you use HIIT, there is no movement of the arrow on the scale. Moreover, it tires and drains you in a way that prevents you from achieving results in strength training in the gym, thereby sabotaging your efforts to build strength and muscle mass.

  • You read the article that deep squats are the best for building your legs. But every time you do them, your hips and lower back are torn to shreds, and you cannot train your legs for the next 10 days. Constant pain prevents your muscles from being fully utilized.
  • Your workout friend says low-intensity aerobic exercise makes her hungry. She notes the difficulty in dieting when she does cardio versus days without it. On the other hand, you consistently lose your appetite after doing cardio. This is probably why cardio allows you to create greater energy deficits.
  • In the gym, you hear a friend brag about how he only needs a few sets of push-ups for his chest muscles, close to giving up every week, and he’s growing like crazy. You don’t see a change until you’ve done 15 to 20 sets of different breast exercises per week. He claims that your workouts are excessive and create too much damage and soreness, but you are recovering well from your workouts.

How do we know who is right? Perhaps everyone is right.

We are often tempted to turn to research to find out how to organize our nutrition and exercise programs, and research serves as a guide or starting point. Keep in mind, however, that studies generally report averages. Individual responses to exercise and nutrition vary enormously between individuals; the averages do not give us this information.

In this article, we’ll dive into some of the critical but rarely discussed factors in evidence-based training programs.