Acute effects of low load resistance training with blood flow restriction on serum growth hormone, insulin-like growth factor-1, and testosterone in patients with mild to moderate unilateral knee osteoarthritis.

Objective: To investigate the acute effects of blood flow restriction (BFR) with single-leg low load resistance exercise and high load resistance exercise on serum insulin-like growth factor-1 (IGF-1), growth hormone (GH), and testosterone in patients with unilateral knee osteoarthritis (OA). Methods: This study recruited 18 postmenopausal female patients with mild to moderate unilateral knee OA, which was then followed by randomly conducting three resistance exercise protocols by drawing lots: 1. A 30% 1-repetition maximum (1-RM) resistance exercise with BFR of 70% arterial occlusive pressure (AOP) (BFR group); 2. A 70% 1-RM resistance exercise without BFR (RES group); 3. A 30% 1-RM resistance exercise without BFR (CON group). Blood lactate (BLA) and muscle growth related hormone levels were tested at 4-time points: before exercise, immediately after exercise, 15 min after exercise, and 30 min after exercise. Results: There was no statistical difference between the indexes in each group before exercise, but the different exercise had different effects on each index and also an interactive effect (P < 0.05). The increase of rating of perceived exertion in the BFR and RES groups, which were of similar magnitude, was greater compared to the levels in the CON group (P < 0.05). Post-exercise BLA levels were lower in the CON group in comparison to the BFR and RES groups (P < 0.05). Rather than the RES group, GH levels of the BFR group were also significantly higher than the CON group (P < 0.05) at 15 min post-exercise. At post- and 15 min after exercise, the CON group recorded significantly lower IGF-1 levels compared to the BFR and RES groups (P < 0.05). At post- and 15 min after exercise, the CON group (P < 0.05) reflected the lowest testosterone levels, followed by the RES group (P < 0.05), and the highest in the BFR group (P < 0.05). Conclusions: Myogenesis-related hormones in women with unilateral knee OA could be increased by high load resistance exercise and low load resistance exercise with BFR on unaffected limb.