A short-term arm-crank exercise program improved testosterone deficiency in adults with chronic spinal cord injury

To determine the influence of arm-crank exercise in reproductive hormone levels in adults with chronic SCI. Further objectives were to assess the influence of arm-crank exercise on muscle strength and body composition.

Seventeen male adults with complete SCI at or below the 5th thoracic level (T5) volunteered for this study. Participants were randomly allocated to the intervention (n = 9) or control group (n = 8) using a concealed method. The participants in the intervention group performed a 12-week arm-crank exercise program, 3 sessions/week, consisting of warming-up (10-15 min) followed by a main part in arm-crank (20-30 min [increasing 2 min and 30 seconds each three weeks]) at a moderate work intensity of 50-65% of heart rate reserve (HRR) (starting at 50% and increasing 5% each three weeks) and by a cooling-down period (5-10 min). Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone and estradiol were determined by ELISA. Muscle strength (handgrip) and body composition (waist circumference [WC]) were assessed.

After the completion of the training program, testosterone level was significantly increased (p = 0.0166;d = 1.14). Furthermore, maximal handgrip and WC were significantly improved. Lastly, a significant inverse correlation was found between WC and testosterone (r =- 0.35; p = 0.0377).

The arm-crank exercise improved reproductive hormone profile by increasing testosterone levels in adults with chronic SCI. A secondary finding was that it also significantly improved muscle strength and body composition in this group.