5. Vitamin D deficiency and athletic performance

Overtraining syndrome results from excessive training load combined with inadequate recovery, leading to decreased athletic performance and increased fatigue. The aim of the study was to measure the impact of vitamin D deficiency on muscle function and inflammation in an excessive training model.

Sixty-six-week-old C57BL/6 mice fed vitamin D-depleted or non-vitamin D diets underwent a 16-week training program with either concentric-dominant (uphill running) or eccentric-dominant (downhill running). A loss of grip strength was observed throughout both types of training. This loss of strength was increased in vitamin D-deficient mice receiving eccentric-dominant training. Balance was decreased in the vitamin D-deficient groups. Exploratory abilities were lower in the vitamin D-deficient mice.

The Th1/Th2 lymphocyte population ratio was increased by approximately 40% by eccentric training combined with vitamin D deficiency, indicating a pro-inflammatory effect. Triceps brachii and plantaris mass were significantly decreased by eccentric training and vitamin D deficiency, respectively. Protein synthesis in both muscles was decreased by 2 by vitamin D deficiency.

In conclusion, excessive eccentric-dominated training combined with vitamin D depletion causes a decrease in physical capacity and atrophy of the triceps brachii. This study should be supplemented by a double-blind clinical study on a group of athletes supplemented with vitamin D or receiving a placebo during a winter phase that will allow their performance after this period to be compared.

Contact : Jérémie Talvas