title: Does vitamin D affect muscle strength and architecture? An isokinetic and ultrasonographic study.
abstract: OBJECTIVE
  The objective of this study was to explore the association between 25- hydroxyvitamin D (25(OH)D) and muscle strength/architecture.
  
  
  METHODS
  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°/sec and 180°/sec and those of ankle flexor/ extensor muscles at 30°/sec and 90°/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°/sec (p=0.007), knee extension at 30°/sec (p=0.038) and 180°/sec (p=0.001), and ankle extension at 30°/sec (p=0.002) and 90°/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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Hacettepe University Medical School, Department of Physical Medicine and Rehabilitation, Ankara, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Kara
authors.affiliation: Ankara Physical Medicine and Rehabilitation Training and Research Hospital, Ankara, Turkey. Email: timurekiz@gmail.com.
authors.forename: Timur
authors.initials: T
authors.lastname: Ekiz
authors.affiliation: Gazi University Medical School, Department of Internal Medicine, Divison of Geriatrics, Ankara, Turkey.
authors.forename: Özgür
authors.initials: Ö
authors.lastname: Kara
authors.affiliation: Ankara Physical Medicine and Rehabilitation Training and Research Hospital, Ankara, Turkey.
authors.forename: Tülay
authors.initials: T
authors.lastname: Tiftik
authors.affiliation: Ankara Physical Medicine and Rehabilitation Training and Research Hospital, Ankara, Turkey.
authors.forename: Fevziye Ünsal
authors.initials: FÜ
authors.lastname: Malas
authors.affiliation: Ankara Physical Medicine and Rehabilitation Training and Research Hospital, Ankara, Turkey.
authors.forename: Sibel
authors.initials: S
authors.lastname: Özbudak Demir
authors.affiliation: Ankara Physical Medicine and Rehabilitation Training and Research Hospital, Ankara, Turkey.
authors.forename: Neşe
authors.initials: N
authors.lastname: Özgirgin
mesh_terms: D000328:Adult; D000842:Ankle; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007717:Knee; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000502:physiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D