From Charles Poliquin
It’s possible to build muscle and lose fat with single-limb training but you must program your workouts correctly in order to get results. Single-limb training is critical to correct structural imbalances, but you can’t do it with just a 15-minute workout as a popular men’s magazine suggests. Research shows that in order to achieve an anabolic response, you need to train large muscle groups first and then finish with structural balance exercises.
For example, an 11-week unilateral training program done by untrained men showed that following workouts in which they performed single-limb arm and leg exercises, there was a significant increase in hormone response to training. On days that they did single-limb arm training without lower body, there was no increase in hormone levels.
This was a unique study design such that on one side of the body the trainees trained the arm and leg whereas on the other side they only trained the arm. The same volume and intensity was used for both sides. Results showed that strength, power, and muscle gains were much greater on the side of the body that trained both the upper and lower body compared to only the arm.
Researchers think it is the much higher anabolic response of growth hormone and testosterone that resulted in the superior gains in the arm trained on the leg/arm day. Not only does a greater anabolic response increase hypertrophy in the trained muscles, it enhances neural adaptations for greater strength.
A second study with a more conventional training design shows the acute effect of unilateral training. Researchers compared the hormone response following a unilateral total body workout with a bilateral workout using the same exercises. Results showed growth hormone and insulin increased significantly after the bilateral workout but there was no hormone response to the unilateral workout.
The take away is that in order to achieve the ideal endocrine response to training you need to start workouts with large muscle mass exercises in the lower body. Start with squats, deadlifts, Olympic lifts, and other multi-joint exercises. Assuming you train with adequate volume and intensity, split squats, step-ups and other single-limb lifts can be included to make up the “meat” or your workout. This strategic programming should dramatically increase hormone secretion once structural balance and smaller muscle mass exercises are started.
Migiano, M., Vingren, J., et al. Endocrine Response Patterns to Acute Unilateral and Bilateral Resistance Exercise in Men. Journal of Strength and Conditioning Research. 2010. 24(8), 128-134.
Uchida, M., Crewther, B., et al. Hormonal Responses to Different Resistance Exercise Schemes of Similar Total Volume. Journal of Strength and Conditioning Research. 2009. 23(7). 2003-2008.
Ronnestad, B., Nygaard, H., et al. Physiological Elevation of Endogenous Hormones Results in Superior Strength training Adaptation. European Journal of Applied Physiology. 2011. 111, 2249-2259.