Rapid increase in plasma growth hormone after low-intensity resistance exercise with vascular occlusion

TLDR

The study examined hormonal and inflammatory responses to low‑intensity resistance exercise with vascular occlusion. Six participants performed 14 repetitions × 5 sets of 20 % 1RM leg extensions while a thigh tourniquet applied ~214 mmHg, and plasma GH, NE, lactate, IL‑6, lipid peroxide, and CPK were measured before and after exercise. The occlusion protocol caused a transient, ~290‑fold increase in GH and marked rises in NE and lactate, while IL‑6 rose more slowly and remained slightly elevated 24 h later; lipid peroxide and CPK were unchanged, indicating that light resistance with occlusion stimulates GH via metabolite accumulation without tissue damage.

Abstract

Hormonal and inflammatory responses to low-intensity resistance exercise with vascular occlusion were studied. Subjects ( n = 6) performed bilateral leg extension exercise in the seated position, with the proximal end of their thigh compressed at 214 ± 7.7 (SE) mmHg throughout the session of exercise by means of a pressure tourniquet. Mean intensity and quantity of the exercise were 20% of 1 repetition maximum and 14 repetitions × 5 sets, respectively. In each set, the subjects repeated the movement until exhaustion. Plasma concentrations of growth hormone (GH), norepinephrine (NE), lacate (La), lipid peroxide (LP), interleukin-6 (IL-6), and activity of creatine phosphokinase (CPK) were measured before and after the exercise was finished and the tourniquet was released. Concentrations of GH, NE, and La consistently showed marked, transient increases after the exercise with occlusion, whereas they did not change a great deal after the exercise without occlusion (control) done at the same intensity and quantity. Notably, concentration of GH reached a level ∼290 times as high as that of the resting level 15 min after the exercise. IL-6 concentration showed a much more gradual increase and was maintained at a slightly higher level than in the control even 24 h after exercise. Concentrations of LP and CPK showed no significant change. The results suggest that extremely light resistance exercise combined with occlusion greatly stimulates the secretion of GH through regional accumulation of metabolites without considerable tissue damage.