Have you ever had a long winter day at work and seemed to miss the short period of daylight? These cold winter days and lack of sunshine can cause a decrease in Serum 25-hydroxyvitamin D levels, commonly known as Vitamin D, which may be affecting your overall exercise performance. According to theAmerican Dietetic Association, Americans should consume approximately 600 IU/day of Vitamin D. Intake and exposure to Vitamin D significantly decreases during the months of January and February. Insufficient Vitamin D levels can hinder aerobic endurance, muscular strength, neuromuscular coordination, and muscle recovery, which make it difficult to exercise optimally.(Kaul 3)
A decrease in Vitamin D levels can influence cardiovascular endurance and resistance exercise and cause them to become more challenging. Compromised levels of Vitamin D promote arterial stiffness. When the arteries stiffen, a limited amount of blood can be transported away from the heart to the active muscles. This decrease in blood flow causes the muscle to fatigue quicker and makes it more difficult to reach anaerobic thresholds and fat burning heart rate zones. (Ardestani 1) Vitamin D also plays a big role with resistance training and initiating muscle contractions. Researchers at the University of North Carolina discovered lower extremity muscular strength to be greater among individuals with sufficient Vitamin D levels compared to individuals with insufficiencies. (Cannel 2)
I am sure we all have been a victim of suddenly slipping on dredded black ice. These incidents seem like bad luck and happen so quickly. However, Vitamin D is greatly associated with nervous system function. An ample amount of Vitamin D levels improves neuromuscular coordination and assists with daily functions, such as balance and reaction time. Older adults are highly prone to Vitamin D insufficiencies and have an even greater risk for fall- related injuries. (Koundourakis 4)
The nervous system and muscular recovery time can also be affected by insufficient Vitamin D levels. Our immune cells contain receptors for Vitamin D which assists in healthy cell replication. (Ardestani 1) Compromised levels can prevent inflammatory responses which slows down muscle recovery, as well as increases the risk for chronic and metabolic diseases.
Here are some tips to increase Vitamin D levels during the winter months.
Small amounts of sun exposure - On sunny, not extremely cold days, go for a brisk 10-20 minute walk during your break at work.
Increase intake of foods that have high sources of Vitamin D- Wild salmon, tuna, eggs and milk contain approximately 450 IUs.
Take your multivitamins - Most multivitamins have approximately 300 IUs.
Ensuring you are consuming and exposing your skin to ample amounts of Vitamin D may assist in reaching your fitness goals during these winter months. Hang in there, only 8 more weeks ‘til Spring!
-Jillian Singleton, MS, EP-C
Exercise Physiologist- Revolution Physical Therapy Weight Loss
1. Ardestani, Afrooz et al. “Relation of Vitamin D Level to Maximal Oxygen Uptake in Adults.” The American journal of cardiology 107.8 (2011): 1246–1249. PMC. Web. 13 Jan. 2018.
2. Cannel J, Hollis B, Sorwnson M. “Athletic Performance and Vitamin D”. Medicine & Science in Sports & Exercise. 41(5):1102-1110, MAY 2009.
3. Kaul A, Glaser S, Hannenemann A. ” Vitamin D is associated with cardiopulmonary exercise capacity: results of two independent cohorts of healthy adults. Britain Nutritional Journal.115(3): 500-8. Feb 2016.
4. Koundourakis N, Avgoustinaki P, Malliaraki N. Muscular effects of vitamin D in young athletes and non-athletes and in the elderly. Hormones 2016, 15(4):471-488.