Musculoskeletal health in ambulatory physically active men with Cerebral Palsy : seasonal variations and the role of vitamin D

Background: Individuals with Cerebral Palsy (CP) show impairments in muscle strength and power. Impairments in strength, in typically developed controls (TDC) low levels of force production and poor bone health are associated with low levels of vitamin D, and a high falls prevalence. It is possible that the severity of musculoskeletal impairments in individuals with CP is exacerbated by living in northern latitudes such as the UK and may contribute to high falls prevalence. Methods: Forty-eight participants were split into two groups of 24 active, ambulant men with CP (Gross Motor Function Classification Score I-II) and 24 healthy TDC completed one in vivo assessment of musculoskeletal health during the winter1, including: Vastus Lateralis anatomical cross-sectional area (VL ACSA), isometric knee extension maximal voluntary contraction (KE iMVC), 10 m sprint, vertical jumps, radius and tibia bones Tus and Zus scores. Plus falls frequency questionnaires to measure fear of falling and risk-taking behaviour were completed by 19 men with CP and 19 TDC. Assessments of vitamin D status through venous samples of serum 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone, dietary vitamin D intake from food diary and total sun exposure via questionnaire were also taken. 16 of the ambulant men with CP and 16 healthy TDC repeated these measures to assess seasonal variations on two separate occasions (the winter and in the summer). Results: Men with CP had 40.5% weaker KE iMVC, 23.7% smaller VL ACSA, 22.2% lower vertical jump, 14.6% lower KE iMVC/VL ACSA ratio, 22.4% lower KE iMVC/body mass (BM) ratio and 25.1% lower KE iMVC/lean body mass (LBM) ratio (all p<0.05). Radius Tus and Zus scores were 1.75 and 1.57 standard deviations lower than TDC, respectively (p<0.05). 25(OH)D was not different between groups, and 90.9% of men with CP and 91.7% of TDC had low 25(OH)D levels when compared to current UK recommendations. 25(OH)D was positively associated with KE iMVC/LBM ratio in men with CP (r = 0.500, p=0.020). Men with ...