Effects of Methylsulfonylmethane (MSM) on exercise-induced oxidative stress, muscle damage, and pain following a half-marathon: a double-blind, randomized, placebo-controlled trial

Oxidative stress and muscle damage occur during exhaustive bouts of exercise, and many runners report pain and soreness as major influences on changes or breaks in training regimens, creating a barrier to training persistence. Methylsulfonylmethane (MSM) is a sulfur-based nutritional supplement that is purported to have pain and inflammation-reducing effects. To investigate the effects of MSM in attenuating damage associated with physical exertion, this randomized, double-blind, placebo-controlled study evaluated the effects of MSM supplementation on exercise-induced pain, oxidative stress and muscle damage.

Twenty-two healthy females (n = 17) and males (n = 5) (age 33.7 ± 6.9 yrs.) were recruited from the 2014 Portland Half-Marathon registrant pool. Participants were randomized to take either MSM (OptiMSM®) (n = 11), or a placebo (n = 11) at 3 g/day for 21 days prior to the race and for two days after (23 total). Participants provided blood samples for measurement of markers of oxidative stress, and completed VAS surveys for pain approximately one month prior to the race (T₀), and at 15 min (T₁), 90 min (T₂), 1 Day (T₃), and 2 days (T₄) after race finish. The primary outcome measure 8-hydroxy-2-deoxyguanine (8-OHdG) measured oxidative stress. Secondary outcomes included malondialdehyde (MDA) for oxidative stress, creatine kinase (CK) and lactate dehydrogenase (LDH) as measures of muscle damage, and muscle (MP) and joint pain (JP) recorded using a 100 mm Visual Analogue Scale (VAS). Data were analyzed using repeated and multivariate ANOVAs, and simple contrasts compared post-race time points to baseline, presented as mean (SD) or mean change (95% CI) where appropriate.

Running a half-marathon induced significant increases in all outcome measures (p < 0.001). From baseline, 8-OHdG increased significantly at T₁ by 1.53 ng/mL (0.86–2.20 ng/mL CI, p < 0.001) and T₂ by 1.19 ng/mL (0.37–2.01 ng/mL CI, p < 0.01), and fell below baseline levels at T₃ by −0.46 ng/mL (−1.18–0.26 CI, p > 0.05) and T₄ by −0.57 ng/mL (−1.27–0.13 CI, p > 0.05). MDA increased significantly at T₁ by 7.3 μM (3.9–10.7 CI, p < 0.001). Muscle damage markers CK and LDH saw significant increases from baseline at all time-points (p < 0.01). Muscle and joint pain increased significantly from baseline at T₁, T₂, and T₃ (p < 0.01) and returned to baseline levels at T₄. Time-by-treatment results did not reach statistical significance for any outcome measure, however, the MSM group saw clinically significant (Δ > 10 mm) reductions in both muscle and joint pain.

Participation in a half-marathon was associated with increased markers of oxidative stress, muscle damage, and pain. MSM supplementation was not associated with a decrease from pre-training levels of oxidative stress or muscle damage associated with an acute bout of exercise. MSM supplementation attenuated post-exercise muscle and joint pain at clinically, but not statistically significant levels.