Does vitamin D affect muscle strength and architecture? An isokinetic and ultrasonographic study

KARA M., Ekiz T., Kara O., Tiftik T., Malas F. U., Demir S. O., ...More

ASIA PACIFIC JOURNAL OF CLINICAL NUTRITION, vol.26, no.1, pp.85-88, 2017 (SCI-Expanded) identifier identifier identifier


Background and Objectives: The objective of this study was to explore the association between 25-hydroxyvitamin D (25(OH)D) and muscle strength/architecture. Methods and study Design: Thirty patients (27 women, 3 men) were allocated into Group I (n=15, mean age; 44.4 +/- 9.4 years) and Group II (n=15, mean age; 39.0 +/- 9.9 years) according to the median of 25(OH)D (<13.7 ng/mL vs >13.7 ng/mL, respectively). Peak torque/body weight of the knee flexor/extensor muscles at 60 degrees/sec and 180 /sec and those of ankle flexor/extensor muscles at 30 degrees/sec and 90 degrees/sec were evaluated by using a Biodex System 3 Pro Multijoint System isokinetic dynamometer. A 7-12 MHz linear array probe was used to evaluate thickness (MT), pennation angle (PA) and fascicle length (FL) of medial gastrocnemius and vastus lateralis muscles. Results: Mean of 25(OH)D was 9.4 +/- 2.5 ng/mL and 20.7 +/- 8.3 ng/mL in Groups I and II, respectively. Although all isokinetic strength parameters were lower in Group I, significant differences were found in knee flexion at 180 degrees/sec (p=0.007), knee extension at 30 degrees/sec (p=0.038) and 180 degrees/sec (p=0.001), and ankle extension at 30 degrees/sec (p=0.002) and 90 degrees/sec (p=0.007). On the other hand, no significant difference was found between the groups regarding MT, PA and FL values (all p>0.05). Conclusion: In light of our results, we can argue that 25(OH)D is associated with muscle strength but not with muscle architecture. Further studies concerning the long-term follow-up effects of 25(OH)D treatment on muscle strength are awaited.