Effects of Testosterone and Resistance Training on Anabolic and Inflammatory Biomarkers Following Spinal Cord Injury

Abstract

Resistance training (RT) evokes skeletal muscle hypertrophy via increasing insulin growth factors-1 (IGF-1) after spinal cord injury (SCI). Muscle hypertrophy increases basal metabolic rate (BMR) following 16 weeks of RT; increase in BMR is also linked positively to adiponectin after SCI. The effects of combining testosterone replacement therapy (TRT) and RT on circulating growth factors, adiponectin and inflammatory biomarkers are still unclear. PURPOSE: To examine the effects of TRT+RT on IGF-1, insulin growth factors binding protein-3 (IGFBP-3), adiponectin and interlukin-6 (IL-6) compared to TRT only in men with SCI. METHODS: Twenty-two men with motor complete SCI were randomized into either 16 weeks of TRT+RT (n = 11) or TRT (n = 11). After overnight fast, IGF-1, IGFBP-3, adiponectin and IL-6 were measured. Evoked progressive RT using neuromuscular electrical stimulation (2 lbs. increments) was administered twice weekly. Daily TRT patches (2-6 mg/day) were applied on both shoulders at bedtime for 16 weeks. RESULTS: IGF-1 showed a decrease (P=0.008) in both TRT+RT (n=11; B2: 169.5±96.5 to PI: 101.5±28 ng/ml) and TRT only (n=11; B2: 136±74 to PI: 99±36 ng/ml) groups. IGFBP-3 increased significantly (P=0.0001) in both TRT+RT (n=11; B2: 1764±665 to PI: 2548.5±853 ng/ml) and TRT (n=11; B2: 1918.5±587 to PI: 2778±967 ng/ml). A significant interaction was noted between TRT+RT and TRT groups in the circulating adiponectin (P=0.024). IL-6 decreased (P=0.039) in TRT+RT (n=8; B2:5.5±5.6 to PI: 2.9±5.4 pg/ml) and TRT (n=10; B2:5.9±6.0 to PI: 3.9±4.4 pg/ml) groups. CONCLUSION: Greater adipose tissue in men with SCI may have resulted in aromatization of testosterone to estradiol that has been previously shown to decrease IGF-1 and increase IGFBP-3. Increased circulating testosterone following TRT+RT may be responsible for suppressing adiponectin but not in the TRT group. Finally, administering TRT with or without RT may elicit anti-inflammatory effects after SCI.