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- [Show abstract] [Hide abstract] ABSTRACT: Objectives To investigate the effects of vitamin D supplementation on muscle strength in healthy individuals. Design A systematic review with meta-analysis. Methods In October 2013 a computerised literature search of three databases (Pubmed, Web of Knowledge and Scopus) was performed. Included in the review were controlled and randomised controlled trials, published in English, which measured muscle strength and serum Vitamin D concentration in participants 18-40 years old. References of identified articles were then cross-checked and citations scanned for additional articles. Quality was assessed using the PEDro scale. Muscle strength and Vitamin D levels were extracted for a meta-analysis on upper and lower limb strength with standardised mean differences calculated to analyse effect. Results Six randomised controlled trials and one controlled trial were identified and quality assessment showed all seven trials were of ‘good quality’. Data was extracted from 310 adults, 67% female, with mean ages ranging from 21.5 to 31.5 years. Trials lasted from 4 weeks to 6 months and dosages differed from 4000 IU per day to 60,000 IU per week. Upper and lower limb muscle strength had a standardised mean difference of 0.32 (95% CI = 0.10, 0.54) and 0.32 (95% CI = 0.01, 0.63) respectively, suggesting Vitamin D supplementation significantly increased muscle strength in the experimental group for upper (P = 0.005) and lower limbs (P = 0.04). Conclusion Vitamin D supplementation increases upper and lower limb strength. Further research should focus on its effect on muscle power, endurance and maximal strength.
- [Show abstract] [Hide abstract] ABSTRACT: Background Evidence shows that anti-pronating foot orthoses improve patellofemoral pain, but there is a paucity of evidence concerning mechanisms. We investigated the immediate effects of prefabricated foot orthoses on (i) hip and knee kinematics; (ii) electromyography variables of vastus medialis oblique, vastus lateralis and gluteus medius during a functional step up task, and (iii) associated clinical measures. Methods Hip muscle activity and kinematics were measured during a step-up task with and without an anti-pronating foot orthoses, in people (n = 20, 9 M, 11 F) with patellofemoral pain. Additionally, we measured knee function, Foot Posture Index, isometric hip abductor and knee extensor strength and weight-bearing ankle dorsiflexion. Findings Reduced hip adduction (0.82°, P = 0.01), knee internal rotation (0.46°, P = 0.03), and gluteus medius peak amplitude (0.9 mV, P = 0.043) were observed after ground contact in the ‘with orthoses’ condition. With the addition of orthoses, a more pronated foot posture correlated with earlier vastus medialis oblique onset (r = − 0.51, P = 0.02) while higher Kujala scores correlated with earlier gluteus medius onset (r = 0.52, P = 0.02). Interpretation Although small in magnitude, reductions in hip adduction, knee internal rotation and gluteus medius amplitude observed immediately following orthoses application during a task that commonly aggravates symptoms, offer a potential mechanism for their effectiveness in patellofemoral pain management. Given the potential for cumulative effects of weight bearing repetitions completed with a foot orthoses, for example during repeated stair ascent, the differences are likely to be clinically meaningful.
- [Show abstract] [Hide abstract] ABSTRACT: Greater frontal and transverse plane hip and knee motion, and delayed gluteus medius and vastus medialis oblique activation have frequently been identified in patellofemoral pain syndrome populations, whilst prefabricated anti-pronation foot orthoses have been reported to reduce symptoms. The aim of the study was to evaluate the effects of such orthoses on hip and knee kinematics, gluteal and vasti muscle activity, kinematic and electromyographic interactions alongside correlations with specific clinical measures. Eighteen asymptomatic individuals (11 male 7 female) had measures taken of static foot posture and ankle range of motion. Hip muscle activity and kinematics were measured using electromyography and an active motion capture system during a step-up task. Order of testing with or without orthoses was determined using a coin toss. Between condition paired t-tests indicated significantly reduced peak hip adduction angles (1.56°, P<0.05) and significantly reduced knee internal rotation (1.3°, P<0.05) in the orthoses condition. Reduced ankle dorsiflexion range of motion correlated with a reduction in hip adduction following the orthoses intervention (r=0.59, P=0.013). The effects of prefabricated orthoses may be partially explained by kinematic alterations that occur proximal to the foot in the kinetic chain. These clinically and biomechanically relevant effects appear more evident in those with reduced underlying ankle motion. Further research is indicated using a symptomatic population to explore the clinical relevance of these observations.
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