Vitamin D, Muscle Function, and Cardiorespiratory Fitness in Adolescents From the Young Hearts Study.
BACKGROUND
Vitamin D insufficiency is common among the adolescent population and may have implications for health outcomes in later life. Few studies have investigated the role of vitamin D status in muscle function and cardiorespiratory fitness (CRF) during adolescence.


OBJECTIVE
The aim of this study was to investigate the association between vitamin D status and fat-free mass (FFM), muscle strength, muscle power, and CRF in a representative sample of adolescents from Northern Ireland.


METHODS
This was a cross-sectional study involving 1015 adolescents (age 12 and 15 y), who had 25-hydroxyvitamin D [25(OH)D] data available as part of the Young Hearts Study 2000.


METHODS
The main outcome measures of this study were FFM (kg) and FFM corrected for height [fat-free mass index; FFM (kg)/height (m(2))], muscle strength (kg), peak muscle power (kW) and VO2 max (CRF; mL/kg/min).


RESULTS
Multinomial regression analyses, controlling for environmental and lifestyle factors, demonstrated that boys age 15 years in the highest tertile of standardized serum 25(OH)D concentration (> 51 nmol/L) had significantly higher muscle strength (β = 3.90; P ≤ .001) compared with those in the lowest tertile (< 32 nmol/L). These results were not evident in any other age-sex group and vitamin D status was not significantly associated with muscle power or CRF in any of the four age-sex groups.


CONCLUSIONS
These results support a role for vitamin D in muscle function in adolescent males and suggest the need for more research in this vulnerable age group.
Northern Ireland Centre for Food and Health (E.L.C., L.K.P., J.J.S., M.S.M.), University of Ulster, Coleraine, Londonderry BT52 1SA, United Kingdom; School of Agriculture, Food and Rural Development (T.R.H.), Human Nutrition Research Centre, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom; School of Food and Nutritional Sciences (K.D.C.), University College Cork, Cork, Cork, Ireland; and Cardiovascular Research Centre (C.A.B.), Queen's University, Belfast BT7 1NN, United Kingdom.
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EL
Carson
Northern Ireland Centre for Food and Health (E.L.C., L.K.P., J.J.S., M.S.M.), University of Ulster, Coleraine, Londonderry BT52 1SA, United Kingdom; School of Agriculture, Food and Rural Development (T.R.H.), Human Nutrition Research Centre, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom; School of Food and Nutritional Sciences (K.D.C.), University College Cork, Cork, Cork, Ireland; and Cardiovascular Research Centre (C.A.B.), Queen's University, Belfast BT7 1NN, United Kingdom.
L K
LK
Pourshahidi
Northern Ireland Centre for Food and Health (E.L.C., L.K.P., J.J.S., M.S.M.), University of Ulster, Coleraine, Londonderry BT52 1SA, United Kingdom; School of Agriculture, Food and Rural Development (T.R.H.), Human Nutrition Research Centre, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom; School of Food and Nutritional Sciences (K.D.C.), University College Cork, Cork, Cork, Ireland; and Cardiovascular Research Centre (C.A.B.), Queen's University, Belfast BT7 1NN, United Kingdom.
T R
TR
Hill
Northern Ireland Centre for Food and Health (E.L.C., L.K.P., J.J.S., M.S.M.), University of Ulster, Coleraine, Londonderry BT52 1SA, United Kingdom; School of Agriculture, Food and Rural Development (T.R.H.), Human Nutrition Research Centre, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom; School of Food and Nutritional Sciences (K.D.C.), University College Cork, Cork, Cork, Ireland; and Cardiovascular Research Centre (C.A.B.), Queen's University, Belfast BT7 1NN, United Kingdom.
K D
KD
Cashman
Northern Ireland Centre for Food and Health (E.L.C., L.K.P., J.J.S., M.S.M.), University of Ulster, Coleraine, Londonderry BT52 1SA, United Kingdom; School of Agriculture, Food and Rural Development (T.R.H.), Human Nutrition Research Centre, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom; School of Food and Nutritional Sciences (K.D.C.), University College Cork, Cork, Cork, Ireland; and Cardiovascular Research Centre (C.A.B.), Queen's University, Belfast BT7 1NN, United Kingdom.
J J
JJ
Strain
Northern Ireland Centre for Food and Health (E.L.C., L.K.P., J.J.S., M.S.M.), University of Ulster, Coleraine, Londonderry BT52 1SA, United Kingdom; School of Agriculture, Food and Rural Development (T.R.H.), Human Nutrition Research Centre, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom; School of Food and Nutritional Sciences (K.D.C.), University College Cork, Cork, Cork, Ireland; and Cardiovascular Research Centre (C.A.B.), Queen's University, Belfast BT7 1NN, United Kingdom.
C A
CA
Boreham
Northern Ireland Centre for Food and Health (E.L.C., L.K.P., J.J.S., M.S.M.), University of Ulster, Coleraine, Londonderry BT52 1SA, United Kingdom; School of Agriculture, Food and Rural Development (T.R.H.), Human Nutrition Research Centre, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom; School of Food and Nutritional Sciences (K.D.C.), University College Cork, Cork, Cork, Ireland; and Cardiovascular Research Centre (C.A.B.), Queen's University, Belfast BT7 1NN, United Kingdom.
M S
MS
Mulhern
D000293:Adolescent; D000367:Age Factors; D015308:Anaerobic Threshold; D001823:Body Composition / Q000502:physiology; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood; D008019:Life Style; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D009752:Nutritional Status; D010809:Physical Fitness / Q000502:physiology*; D012143:Respiratory Physiological Phenomena; D012737:Sex Factors; D014807:Vitamin D / Q000502:physiology*
D006887:Hydroxycholecalciferols; D014807:Vitamin D