{"id":890,"date":"2018-07-08T09:32:00","date_gmt":"2018-07-08T09:32:00","guid":{"rendered":"https:\/\/drmirkin.com\/2018\/07\/08\/lack-of-vitamin-d-may-harm-exercisers\/"},"modified":"2023-04-23T16:51:53","modified_gmt":"2023-04-23T16:51:53","slug":"lack-of-vitamin-d-may-harm-exercisers","status":"publish","type":"post","link":"http:\/\/drmirkin.com\/?p=890","title":{"rendered":"Lack of Vitamin D May Harm Exercisers"},"content":{"rendered":"

A study in mice suggests that having low levels of vitamin D may harm athletes and exercisers by limiting how long they can exercise (Aging<\/em>, June 2018). Six-month old mice were put on a low vitamin D diet for one year. A six-month-old mouse is equivalent to a 25 year old human and one mouse-year equals 25 human-years. After two weeks, the mice on the low vitamin D diet developed blood levels of vitamin D under 15 ng\/ml, (equivalent to low levels in humans), where they remained for the entire study. They did not lose strength, but they lost a lot of their endurance (their ability to sustain exercise). The authors believe that this implies a decrease in their ability to take in and use oxygen. The mice also lost some muscle size. This study may be important for humans because vitamin D deficiency disease is defined as less than 12 ng\/ml and vitamin D insufficiency borderline disease is less than 20 ng\/ml. More than 35 percent of North Americans have these low levels, particularly in the winter.<\/p>\n

Lack of Vitamin D Associated with Muscle and Tendon Injuries<\/strong>
\nDuring my competitive running career, I spent more time injured than training because of wintertime muscle injuries in Boston and Washington, D.C. Many years later, I found the probable cause: my wintertime vitamin D3 blood level was below 20 ng\/ml (normal for the general population is >20 ng\/ml and for athletes may be >30). Since I moved to Florida nine years ago, I have not had even one wear-and-tear sports injury. I now know that people genetically susceptible to vitamin D deficiency are the ones most likely to suffer muscle weakness, injuries and poor athletic performance. Many exercisers and competitive athletes are vitamin D deficient even if they live in the sunbelt.<\/p>\n

Vitamin D deficiency is associated with:
\n\u2022 decreased athletic performance (Molecular Aspects of Medicine<\/em>, June 2005;26(3):203-219),
\n\u2022 muscle weakness (Scandinavia Journal of Medicine & Science in Sports<\/em>, Oct 2009), and
\n\u2022 increased risk for athletic injuries (Current Opinion in Clinical Nutrition & Metabolic Care<\/em>, November 2009; Molecular Aspects of Medicine<\/em>, December 2008; Arthroscopy<\/em>, Dec 21, 2017).<\/p>\n

Genetics and Vitamin D Deficiency<\/strong>
\nA report from the University of Toronto showed that genetic factors cause some people to develop signs and symptoms of severe vitamin D deficiency (Clinical Biochemistry<\/em>, July 2009). People who are genetically at increased risk for vitamin D deficiency are at increased risk for injuries when they try to exercise vigorously in the winter. Lack of vitamin D can weaken muscles (Lancet<\/em>, Mar 1976;20;1(7960):626-9) and taking that vitamin can correct that weakness (Aging-Clinical and Experimental Research<\/em>, December 2000;12(6):455\u2013460). Vitamin D acts directly on specific receptors in muscles to make them stronger and to help prevent injuries (Scandinavian Journal of Medicine & Science in Sports<\/em>, April 2010;20(2):182-90).<\/p>\n

How Lack of Vitamin D is More Harmful in Older People<\/strong>
\nAs people age, they become increasingly susceptible to muscle weakness and falls caused by lack of vitamin D (Molecular Aspects of Medicine<\/em>, June 2005). Muscles are made of thousands of individual fibers that are classified into two types: slow twitch fibers that govern endurance and fast twitch fibers that govern primarily strength and speed. Vitamin D specifically helps to maintain the function of the fast twitch strength fibers (Calcif Tissue Int<\/em>, 2013;92:151\u2013162). With aging, you lose muscle fiber; for example, the vastus medialis muscle in the front of the upper leg typically has about 800,000 fibers in a 20 year old, but only 250,000 in a 60 year old. Vitamin D slows this loss of muscle fibers, preserves muscle strength and helps to prevent falls, while lack of vitamin D increases loss of fibers, muscle weakness and falls (Pediatric Clinics of North America,<\/em> June 2010).<\/p>\n

My Recommendations<\/strong>
\nYou probably do not need to take vitamin D pills if your blood level of hydroxy vitamin D is above 30 ng\/ml unless you have a condition that your doctor feels puts you at increased risk for the signs and symptoms of a deficiency. You can take up to 1000 IU\/day of vitamin D pills if your blood levels are below 30 ng\/ml. Most researchers and clinicians now feel that, with few exceptions, high doses of vitamin D are not beneficial and are potentially harmful. People who could possibly benefit from treating low blood levels of hydroxy vitamin D include those who:
\n\u2022 are inactive and do not go outdoors
\n\u2022 suffer from generalized muscle and joint pain
\n\u2022 are athletes with recurrent injuries and decreased performance
\n\u2022 have weak bones (osteoporosis)
\n\u2022 are diabetic, particularly if LDL cholesterol is over 100
\n\u2022 have an auto-immune disease
\n\u2022 are critically ill or debilitated
\n\u2022 suffer from muscle pain from taking statin drugs
\nI believe that sunlight offers benefits that cannot be obtained just by taking vitamin D pills, but take proper precautions to avoid skin cancer<\/a>.<\/p>\n

Checked 4\/20\/23<\/p>\n","protected":false},"excerpt":{"rendered":"

A study in mice suggests that having low levels of vitamin D may harm athletes and exercisers by limiting how long they can exercise. Many exercisers and competitive athletes are vitamin D deficient even if they live in the sunbelt.<\/p>\n","protected":false},"author":1,"featured_media":1008,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[6],"tags":[],"class_list":["post-890","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-fitness"],"_links":{"self":[{"href":"http:\/\/drmirkin.com\/index.php?rest_route=\/wp\/v2\/posts\/890","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/drmirkin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/drmirkin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/drmirkin.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/drmirkin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=890"}],"version-history":[{"count":0,"href":"http:\/\/drmirkin.com\/index.php?rest_route=\/wp\/v2\/posts\/890\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/drmirkin.com\/index.php?rest_route=\/wp\/v2\/media\/1008"}],"wp:attachment":[{"href":"http:\/\/drmirkin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=890"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/drmirkin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=890"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/drmirkin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=890"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}