Increase strength and muscle size by using short rest intervals to achieve the greatest testosterone response to training. An interesting new study in the Journal of Strength and Conditioning Research shows that to produce the greatest results, it’s essential you program all elements of your training, including rest, load, volume, type of exercise, and tempo.
This study used two traditional training protocols and compared the effect of 60- or 90-second rest intervals on testosterone and cortisol response in trained young men. A hypertrophy protocol used an intensity of 70 percent of the 1RM with 3 sets of 10 reps, and a strength protocol used an intensity of 85 percent of the 1RM with 8 sets of 3 reps. Both protocols trained the barbell bench press, back squat, lat pull-down, and knee extension.
Results showed that the 60-second rest interval using the hypertrophy protocol produced a 22.5 percent increase in testosterone response, which was the greatest increase of all trials. The hypertrophy protocol using 90-second rest intervals produced the second greatest testosterone response, boosting testosterone by 20 percent. Still significant, both rest intervals of 60 and 90 seconds using the strength protocol increased testosterone by about 13 percent. None of the protocols increased cortisol, indicating these protocols can help you gain muscle and strength without causing too much stress.
The reason you want to make sure you elevate testosterone as much as possible is that it increases protein synthesis in men of all ages, and can also stimulate other anabolic hormones such as growth hormone and insulin-like growth factor-1 (IGF-1). Both are critical for increasing muscle mass and improving body composition. IGF-1 is often overlooked as a valuable anabolic hormone, but it is potentially the best for reducing muscle protein degradation, while “kick starting” muscle building. Another benefit of testosterone is that it increases the number of satellite cells, which must be present for muscle hypertrophy to occur—more satellite cells means more muscle growth.
This study comes after a few recent studies suggesting that testosterone response to training is very individualized, varying greatly based on factors such as training experience and diet. Other findings have shown no statistically significant testosterone response to protocols that do not use total body training, are restricted to machine-based training, or use an inadequate volume load.
Researchers suggest the key to boosting testosterone is to use large muscle group lifts with training cycles that favor hypertrophy and strength protocols and shorter rest periods. The key is to elevate lactate during training to increase the catecholamine hormones, which boosts testosterone. Such a method will also elevate growth hormone and further support body composition.
Be aware that although shorter rest intervals may require slightly lighter loads, they can increase motor unit recruitment if programmed properly. The greater motor unit recruitment will use more muscle fibers and allow greater hormone-tissue interaction within a larger percentage of muscle mass. Recent studies have shown that only the muscles you train will benefit from circulating anabolic hormones like testosterone.
Villanueva, M., Villanueva, M., et al. Acute Hormonal Responses to Various Resistance Training Schemes. Journal of Strength and Conditioning Research. 2012. Published Ahead of Print.