Can riboflavin reduce muscle soreness?

No one enjoys walking up the stairs after leg day. For most people, muscle pain is a simple nuisance, but it can be a tremendous limitation for performance athletes. Technically, post-exercise muscle pain is called delayed onset muscle soreness (DOMS). DOMS is noticeable within 24 hours of finishing a workout, but it tends to peak 24-72 hours afterward. The detrimental effectsPMID: of DOMS on athletic performance are well documented and include reduced joint range of motion, reduced strength and power output, and alteration of exercise technique to compensate for muscle soreness - all of which can increase the risk of injury.

Exercise-induced muscle damage and DOMS tend to be caused by novel stimuli, but this isn’t set in stone. Exercise duration and intensity are also important determinants. Several mechanisms have been proposed^[1] to contribute to DOMS, including damage to the muscle fibers and connective tissue and increased levels of inflammation and oxidative stress. Exercising for longer durations or at higher intensities, even when the exercise is familiar, can cause greater levels of physical damage to muscle fibers and connective tissue that lead to a more pronounced inflammatory response. The known roles of oxidative stress and inflammation in DOMS have led to many investigations into the use of antioxidant and anti-inflammatory foods^[2] and supplements^[3]. Some examples include vitamins C and E, polyphenols such as EGCG, carotenoids, and omega-3 fatty acids. Non-steroidal anti-inflammatory drugs (NSAIDs), particularly aspirin and ibuprofen, have also been investigated^[4] for their ability to affect DOMS.

Riboflavin, also known as vitamin B₂, is an essential vitamin that has antioxidant properties^[5]. The RDA for riboflavin is set at 1.3 milligrams per day for adult men and 1.1 milligrams for adult women. There is no established upper limit for toxicity and deficiency (ariboflavinosis) is rare due to riboflavin’s widespread abundance in food. It operates primarily through two derivatives: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which function as coenzymes for a wide variety of oxidation-reduction reactions necessary for life. The redox chemistry of riboflavin is depicted in Figure 1.

Several studies^[6][7] have suggested that physical activity may increase riboflavin requirements. However, early supplementation studies reported that riboflavin supplementation failed to improve athletic performance in women^[8], children^[9], and elite swimmers. A nine-month randomized crossover trial in competitive long-distance runners found no benefit^[10] of multivitamin supplementation (providing 60 milligrams of riboflavin) on athletic performance despite a significant increase^[11] in riboflavin status.

To date, the research into riboflavin supplementation and athletics has focused on chronic performance adaptations. Whether riboflavin supplementation might provide a protective role or enhanced recovery from exercise-induced muscle damage and DOMS is unknown. The study under review investigated whether the acute ingestion of a high-dose riboflavin supplement would reduce muscle pain and soreness during and after the completion of an ultramarathon, as well as improve functional recovery after the event.

Exercise-induced muscle damage and delayed-onset muscle soreness (DOMS) impair athletic performance and increase the risk for injury. Inflammation and oxidative stress are known to play a role in these detrimental effects. Riboflavin (vitamin B₂) is an essential vitamin that functions as an antioxidant and its requirements may be increased with regular exercise training. The study under review investigated the effects of high-dose riboflavin supplementation on muscle pain and soreness during and after an ultramarathon, as well as its effects on functional recovery after the event.