Concentric Training Blunts Growth Hormone Response to Eccentric Exercise

Growth hormone is a potent anabolic hormone that promotes muscle protein synthesis. Muscle tension is the most important factor increasing muscle size. Eccentric exercise (lengthening contractions) is important for building muscle size and strength because it increases muscle tension and anabolic hormones more than concentric exercise (shortening contractions).

Jeong-Su Kim from Florida State University and colleagues found that doing concentric exercise a week before a high-intensity eccentric workout blunted the growth hormone response. While this study was interesting, its practical value is unclear. The value of a training program is its effects on strength, power, and muscle size. We need studies showing the relationship between hormone levels, program structure, and gains in muscle function. (International Journal Sports Medicine, 31: 95-100, 2010)