Antioxidants don’t reduce muscle soreness after exercise

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Consuming extra antioxidants through foods or supplements may not reduce muscle soreness after exercise, s a research review of 50 studies suggests.

Reuters Health reports that researchers focused on “delayed onset muscle soreness,” the type of muscle pain or tenderness that typically peaks 24 to 72 hours after a strenuous workout. Some previous research has linked antioxidants to the prevention of cellular damage that can potentially result in sore muscles, but results have been mixed.

Data for the current analysis came from 50 studies with a total of 1,089 participants, ages 16 to 55. Across all of these studies, researchers didn’t find a meaningful connection between antioxidants in foods or supplements and the amount of muscle soreness at 6, 24, 48, 72, or 96 hours after workouts.

“The findings of our study suggest that antioxidants do reduce soreness, but the effect is so small it may not be meaningful,” said study leader Mayur Ranchordas of Sheffield Hallam University in the UK. “People should probably avoid taking antioxidants for recovery,” Ranchordas is quoted in the report as saying.

Antioxidant supplements are often marketed in health food stores as a workout recovery aid. The idea that they antioxidants might ease muscle soreness after intense workouts stems from their role in potentially halting or slowing the development of what’s known as oxidative stress, researchers note.

As the body uses oxygen, it produces by-products called free radicals that can damage cells and tissues. The damage by oxygen free radicals is known as oxidative stress. Foods rich in antioxidants include a variety of berries like blueberries, cranberries, goji berries and elderberries as well as dark chocolate, pecans, artichokes and kidney beans.

There are several limitations in the current analysis, including the wide variety of exercise types and intensities as well as the range of different types of antioxidant exposure from foods and supplements, the authors note.

Still, the results suggest that it doesn’t make sense for athletes to spend lots of money on antioxidant supplements to help with recovery from strenuous exercise, said Troy Merry, a nutrition researcher at the University of Auckland in New Zealand who wasn’t involved in the study.

“There are certain strategies that athletes use following exercise to improve recovery such as ice baths, massage, ensuring adequate macronutrients (carbohydrate and protein) intake during and following exercise,” Merry said. “However, how much these strategies actually reduce muscle soreness is debatable, and depends on the type of exercise being undertaken,” Merry added.

The report says the approach to recovery should depend on the type of sport as well as the intensity and frequency of exercise. “It is also important to consider what the goal of exercise you are undertaking is, as soreness is associated with important processes that cause your muscle to adapt to exercise stress and improve its function overtime,” Merry said. “So, if you don’t have to perform at your absolute best in the days following an exercise session, then some soreness is probably good.”

Abstract
Objective: To determine whether antioxidant supplements and antioxidant-enriched foods can prevent or reduce delayed-onset muscle soreness after exercise.
Methods: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, SPORTDiscus, trial registers, reference lists of articles and conference proceedings up to February 2017.
Results: In total, 50 studies were included in this review which included a total of 1089 participants (961 were male and 128 were female) with an age range of 16–55 years. All studies used an antioxidant dosage higher than the recommended daily amount. The majority of trials (47) had design features that carried a high risk of bias due to selective reporting and poorly described allocation concealment, potentially limiting the reliability of their findings. We rescaled to a 0–10 cm scale in order to quantify the actual difference between groups and we found that the 95% CIs for all five follow-up times were all well below the minimal important difference of 1.4 cm: up to 6 hours (MD −0.52, 95% CI −0.95 to −0.08); at 24 hours (MD −0.17, 95% CI −0.42 to 0.07); at 48 hours (mean difference (MD) −0.41, 95% CI −0.69 to −0.12); at 72 hours (MD −0.29, 95% CI −0.59 to 0.02); and at 96 hours (MD −0.03, 95% CI −0.43 to 0.37). Thus, the effect sizes suggesting less muscle soreness with antioxidant supplementation were very unlikely to equate to meaningful or important differences in practice.
Conclusions: There is moderate to low-quality evidence that high-dose antioxidant supplementation does not result in a clinically relevant reduction of muscle soreness after exercise of up to 6 hours or at 24, 48, 72 and 96 hours after exercise. There is no evidence available on subjective recovery and only limited evidence on the adverse effects of taking antioxidant supplements.

Authors
Mayur K Ranchordas, David Rogerson, Hora Soltani, Joseph T Costello

Reuters Health report
British Journal of Sports Medicine abstract


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