Growth hormone and IGF-1 are highly anabolic hormones that trigger increases in muscle mass and strength. Arginine and ornithine are well-known nutritional stimulators of growth hormone release. IGF-1 increases in response to elevated growth hormone levels.
Polish researchers, in a study on well-trained strength athletes, showed that supplementing arginine and ornithine for three weeks resulted in a nearly 50 percent increase in growth hormone and IGF-1 levels, following an intense weight training workout. The supplement also decreased IGF-1 binding protein, which increased the biological availability of the hormone.
While the results of this study are extremely interesting and potentially valuable, we don’t know the long-term effectiveness of the supplements in chronically elevating anabolic hormones, or their effects on increasing muscle mass and strength.
Try this: Take 5-10g of Arginine without food 30-45 minutes before working out and 5g to 10g of Ornithine one hour before a workout and prior bedtime.
Source: Journal Strength Conditioning Research, 24: 1082-1090, 2010