Oral L-Arginine Before Resistance Exercise Blunts Growth Hormone in Strength Trained Males

Abstract

Acute resistance exercise and L-arginine have both been shown to independently elevate plasma growth hormone (GH) concentrations; however, their combined effect is controversial. The purpose was to investigate the combined effects of resistance exercise and L-arginine supplementation on plasma L-arginine, GH, GH secretagogues, and IGF-1 in strength trained participants. Fourteen strength trained males (age: 25 ± 4 y; body mass: 81.4 ± 9.0 kg; height: 179.4 ± 6.9 cm; and training experience: 6.3 ± 3.4 y) participated in a randomized double-blind crossover design (separated by ~7 days). Subjects reported to the laboratory at 08:00 in a fasted state, consumed L-arginine (ARG; 0.075 g·kg-1 body mass) or a placebo (PLA) before performing an acute bout of resistance exercise (3 sets of 8 exercises, 10 repetitions at ~75% 1RM). Blood samples were collected at rest, before exercise, and at 0, 15, 30, and 60 min of rest-recovery. The ARG condition significantly increased plasma L-arginine concentrations (~120%) while no change was detected in the PLA condition. There were no differences between conditions for GH, GH-releasing hormone, ghrelin, or IGF-1 at any time point. GH-inhibiting hormone was significantly lower in the ARG condition. However, integrated area under the curve for GH was blunted in the ARG condition (L-arginine = 288.4 ± 368.7 vs. placebo = 487.9± 482.0 min·ng·mL1, p < .05). L-arginine ingested before resistance exercise significantly elevated plasma L-arginine concentration but attenuated plasma GH in strength trained individuals despite a lower GHIH. Furthermore our data shows that the GH suppression was not due to a GH or IGF-1 induced autonegative feedback loop.

ISSN exercise & sports nutrition review update: research & recommendations

“…These authors reported that arginine administration failed to impact muscle protein synthesis or femoral artery blood flow. Growth hormone levels did rise in response to arginine ingestion, which contrasts with the findings of Forbes et al, [ 275 ] who reported a blunting of growth hormone production after acute ingestion of arginine in strength trained males. Regardless, the Tang study [ 274 ] and others [ 276 , 277 ] failed to link the increase in growth hormone to changes in rates of muscle protein synthesis.…”

Effects of Chronic Supplementation of L‐Arginine on Physical Fitness in Water Polo Players

“…The other possibility resides in the ability of citrulline to shift the energy metabolism to more anaerobic pathways and ameliorating mitochondria activity, through antioxidant properties [35]. Otherwise, L-Arginine has also been shown to stimulate the release of growth hormone (GH) [36,37], which is a potent anabolic agent that favors cell growth and body energetics, which promotes muscle hypertrophy [38,39]. Many effects of L-Arginine supplementation are also linked to improved carbohydrate oxidation and oxygen efficiency [40,41], with reduced exercise-induced production of ammonia, lactate, fatty acids, and fat oxidation [42,43].…”

Effect of argi+ and multi maca food supplements on sportsmen’s physical and functional capacity

“…Analogical data indicates S Forbes.et al (2014) [31], they state that usage bigger amounts of L-arginine increases the concentration of growth hormone in strength trained males. However, ARGI+ in combination with Multi Maca supplementation more influences aerobic capacity (p = 0,047 and p = 0,048).…”