Study: Vitamin D Linked to Muscle Recovery

British lab finds connection between low vitamin D and muscle fatigue

From the sunlight-is-good-for-you department:

Researchers in England may have discovered a missing link between vitamin D, a hormone derived from exposure to sunlight, and muscle fatigue. A new study in the Journal of Clinical Endocrinology and Metabolism reports on the connection between vitamin D deficiency and a muscle’s ability to recover during exercise.

The researchers at Newcastle University tested twelve people with vitamin D deficiency for muscle fatigue before and after treatment with vitamin D supplements. They found that 10 to 12 weeks of treatment significantly improved the patients’ muscle recovery time.

“When we correct the Vitamin D deficiency we actually improve their long-term energy production,” said lead researcher Dr. Akash Sinha, a clinical research fellow at Newcastle University.

“The novel thing is finding the missing link between mitochondria, fatigue and vitamin D,” he said.

Mitochondria are cellular “power plants” that produce some of the energy muscles use to contract. While a sprinter wouldn’t have much to gain from increased mitochondrial efficiency, said Dr. Sinha, someone doing a longer, slower-burn exercise might notice a difference.

“When we do a longer distance walk,” said Sinha, “we rely more on the mitochondrial energy production.”

During the experiment, an MRI machine scanned each subject’s calf muscle while a device put the leg through a repetitive motion similar to climbing stairs. The scan detected the presence of phosphocreatine, a molecule produced by mitochondria to aid energy production.

The faster the muscle replenishes its phosphocreatine, the better the mitochondria are working—and the faster the muscle recovers.

Although the researchers didn’t study athletes, the connection between vitamin D and muscle fatigue hints at broader applications.

“The question is, does this study have implications for athletes or those without vitamin D deficiency," said Dr. Sinha. "Very possibly yes.”

In a parallel study of 60 healthy adults, Dr. Sinha and colleagues found a correlation between vitamin D levels and mitochondrial function. The higher the vitamin D level, they found, the higher the function; the lower the level, the lower the function.

Don’t pop vitamin D pills before your workout just yet, though.

Unlike the other study, this one was not longitudinal and therefore requires further verification.

More research is needed to determine how exactly vitamin D reduces fatigue and whether it can, in fact, boost performance in healthy athletes.

Read the abstract here.