Combined extracts of Garcinia mangostana fruit rind and Cinnamomum tamala leaf supplementation enhances muscle strength and endurance in resistance trained males

Abstract

Background: A proprietary composition GMCT contains extracts of two popular Asian herbs viz., Garcinia mangostana (GM) fruit rind and Cinnamomum tamala (CT) leaf. We systematically evaluated physical performance and muscle strength enhancing ability of GMCT in a preclinical mouse model followed by a 42-days double-blind placebo controlled human trial in resistance trained adult males. Methods: Four groups of Swiss albino mice (20-30g body weight) (n=6) were fed a standard laboratory diet and given Carboxymethylcellulose sodium (CMC), 150mg/kg GMCT (GMCT-150), 300mg/kg GMCT (GMCT-300) or 50mg/kg Oxymetholone (OXY) via oral gavage for 21days. On day 22, the animals' physical performance and muscle strength were assessed in a forced swimming test (FST) and forelimb grip strength experiment, respectively. In the human trial, thirty-eight resistance-trained young adults (mean age 26.32±4.39years, body weight 67.79±12.84kg, BMI 22.92±3.54kg/m2) completed the trial. The participants received either GMCT (n=19; 800mg daily) or matched placebo (n=19) for 42days. As primary variables, 1-RM bench press, 1-RM leg press, and leg extension repetitions were measured at baseline and on days 14, 28 and 42 of the intervention. Anthropometric parameters and serum markers such as free testosterone, insulin-like growth factor 1 (IGF-1), insulin and lactate were also measured before and after the intervention. Results: GMCT-300 mice showed significant improvement in swimming time (GMCT: 395.3±81.70s vs. CMC: 271.6±56.86s; p=0.0166), distance (GMCT: 341.22±65.88m vs. CMC: 260.84±49.15m; p=0.0461) and grip strength (GMCT: 43.92±6.97N vs. CMC: 35.0±6.92N; p=0.0490), compared with the CMC group. At the end of the 42-day human trial, the per protocol analyses reveal that mean changes from baseline 1-RM bench press (GMCT: 23.47±10.07kg vs. PL: 3.42±2.06kg; p<0.0001), leg press (GMCT: 29.32±16.17kg vs. PL: 5.21±1.72kg; p<0.0001), number of leg extension repetitions (GMCT: 6.58±2.57 vs. PL: 2.05±1.22; p<0.0001) in GMCT group were significantly improved, compared with placebo. Intergroup difference analyses show that the changes from baseline left arm (GMCT: 1.09±0.36cm vs. PL: 0.68±0.42cm; p=0.0023), right arm (GMCT: 1.50±0.44cm vs. PL: 1.11±0.43cm; p=0.0088) circumference and lean mass (GMCT: 2.29±2.09kg vs. PL: 0.52±2.58kg; p=0.0404) in GMCT group were also significantly improved, compared with placebo. In comparison to placebo, GMCT supplementation did not improve free testosterone, IGF-1, insulin or lactate levels. Parameters of clinical biochemistry, hematology, urine and vital signs of the participants were within the normal range. Conclusion: GMCT supplementation is effective in increasing muscle strength, muscle size and, total lean mass, as well as endurance performance.