Sprints Plus Weights Optimize Hormones
From Charles Poliquin
Build muscle and lose fat with workouts that elicit the optimal hormone response to training. New research in the European Journal of Applied Physiology shows which exercise modes are best in order to increase the muscle building, fat burning hormones testosterone and growth hormone. This study tells you what not to do if you want to be lean and strong.
Researchers compared the effect on hormone levels of a short sprint session, a weight workout, and an endurance run. Participants did either two 30-sceond all-out sprints, cycled for 30 minutes at 70 percent of maximal, or did a 30-minute weight training workout using loads of 75 percent of the 1RM with 1 minute rest periods. Obviously, the work load wasn’t equal between modes. Rather, the purpose was to identify how each type of exercise acutely affects hormone response independently of work load or adaptation.
Results showed that the weight training workout is the only one to lead to a significant increase in testosterone. The sprint workout increased growth hormone, insulin, and cortisol, which indicates that it would be the ideal type of workout if your goal is to lose fat. Researchers note that more sprint repetitions would be necessary for fat loss, but the hormone response was ideal.
High-intensity exercise that increases insulin will facilitate muscle protein and glycogen synthesis, while the increase in growth hormone after the workout will increase the burning of free fatty acids as an energy source, producing fat loss over the long term.
The endurance workout elevated cortisol and growth hormone, while decreasing insulin. This indicates that the body is sparing glycogen stores so as to be able to maintain function as exercise continues at a steady state. This is key because it calls our attention to the reason that aerobic exercise is not effective for losing fat or building muscle.
In fact, the central purpose of aerobic exercise is to teach the body to be as efficient as possible and spare as much energy while doing the greatest amount of work. Nothing about aerobic exercise is in line with the goals of fat loss or muscle building.
In contrast, if you want to get lean, you need to generate physiological stress to produce as much lactic acid and growth hormone as possible. Lactic acid buildup is associated with a subsequent growth hormone release, which, as already mentioned, has the ability to significantly increase the body’s ability to burn fat for energy, while turning off its fat-storage mechanisms.
Research shows there is a dose-response relationship between exercise intensity and growth hormone after exercise. For example, one study found that in response to 30 minutes of exercise, athletes who ran at the highest intensity experienced the greatest increase in growth hormone, which was the strongest marker for the body’s ability to burn fat after the workout.
Likewise, if you want to build muscle, you need to apply a lot of “stress” to the muscle and overload it with tension or weight. The continual loading will cause the muscle to adapt and grow bigger over time. In addition, a high degree of tension has been linked with anabolic hormone response of testosterone, which is just what we saw in the study in the EJAP. The one problem with the workout used in that study is that it didn’t include enough volume for building muscle or intensity for building strength. To build muscle, train a higher volume to produce a greater testosterone, growth hormone, and insulin-like growth factor-1 response.
To review, if you want to lose fat, do weight training and intervals. If you want to build muscle, overload the muscle with tension by lifting weights. If you want to be efficient but weak, do aerobic exercise. If you want to live long and healthy, do weight training that includes both heavy and powerful exercises.
Stokes, K., et al. Different Responses of Selected Hormones to Three Types of Exercise in Young Men. European Journal of Applied Physiology. 2013. 113, 775-783.