Acute effects of implementing blood flow restriction, static and dynamic stretch during rest intervals of resistance exercise on growth hormone, lactic acid and nitric oxide levels in trained males

The purpose of the study was to investigate the acute effects of blood flow restriction (BFR), static (SS) and dynamic (DS) stretching during rest between sets of a resistance session on serum levels of growth hormone (GH), lactic acid (LA), and nitric oxide (NO) levels in men.

Twenty-eight healthy men with at least one year of regular resistance training (age: 22.28±1 years, BMI: 23.72±1 kg/m2, and fat percentage: 13.15±0.6%) participated in this study voluntarily and were randomly divided into 4 groups: blood flow restriction (BFR,30% 1RM) Static-Stretching (SS, 75% 1RM), Dynamic-Stretching (DS, 75% 1RM) and traditional resistance exercise (TRE, 75% 1RM). Resistance exercise (unilateral front knee extension on the machine) included 1 set of 30 repetition plus 3 sets of 15 repetitions for BFR and 4 sets of 15 repetitions for other groups. For BFR and other groups respectively 90 sec and 60 sec rest intervals implemented. The SS and DS groups performed static stretching on the same leg immediately after each set for 60 seconds. Serum levels of growth hormone, lactate, and nitric oxide were measured before and immediately after exercise sessions.

All four types of activities significantly increased GH, LA, and NO immediately after exercise (P=0.001). But no significant differences were observed between conditions.

Based on the findings, it can be concluded that incorporating different stretching methods (SS or DS) or utilizing BFR during rest intervals, at least for one exercise in a unilateral condition, does not provide any additional benefits compared to inactive rest intervals in the traditional resistance exercise method.