The impact of seasonal variations in vitamin D in active ambulatory men with cerebral palsy: A longitudinal cross-sectional comparison study

Abstract

Abstract Purpose To identify the magnitude and impact of seasonal variations in vitamin D in physically active, ambulatory men with cerebral palsy on neuromuscular performance outcomes and bone indices. Materials & Methods A longitudinal observational study, in sixteen ambulant men with cerebral palsy aged 21.0 ± 1.3 years and 16 healthy, physical activity matched, typically developed controls aged 25.4 ± 2.6 years, completed assessments of serum 25-hydroxyvitamin D and parathyroid hormone during winter and summer. Neuromuscular outcomes included Vastus Lateralis size, knee extensor strength, 10 m sprint, vertical jumps, and grip strength. Bone ultrasounds were performed to obtain radius and tibia T and Z scores. Results Men with cerebral palsy and typically developed controls showed a 70.5% and 85.7% increase in serum 25-hydroxyvitamin D from winter to summer months (p < 0.05), respectively. Neither group showed seasonal effects on neuromuscular outcomes muscle strength, size, vertical jump or tibia and radius T and Z scores. A seasonal interaction effect was seen in the tibia T and Z scores (p < 0.05). Conclusions There was similar seasonal increases in 25-hydroxyvitamin D observed in men with cerebral palsy and typically developed controls, but serum 25-hydroxyvitamin D levels were still considered insufficient to improve bone or neuromuscular outcomes.