Effect of daily Vitamin D3 Supplementation on Muscle Health: An Individual Participant Meta-Analysis

Background The role of vitamin D on muscle health is debated. Methods An individual participant metanalysis of four randomized placebo-controlled trials, investigating short term (three to nine months) effects of vitamin D3 in moderate (2800 IU) to high (7000 IU) daily oral doses on muscle health and quality of life (QoL). Inclusion criteria were either obesity (N=52), newly diagnosed primary hyperparathyroidism (N=41), Graves’ disease (N=86) or secondary hyperparathyroidism (N=81). Results Overall (N=260) as well as in a subgroup analysis including only vitamin D insufficient (25(OH)D< 50 nmol/L) individuals (N=176), vitamin D supplementation did not affect measures of muscle health (isometric muscle strength, Timed Up and Go test, Chair Rising Test, body composition, and balance) or QoL. However, a beneficial effect was present on QoL (physical component score) in vitamin D deficient (25(OH)D≤ 25 nmol/L) individuals (N=34). Overall, relative changes in 25(OH)D inversely affected maximum muscle strength in a dose response manner. Stratified into BMI </≥ 30 kg/m 2, vitamin D supplementation had divergent effects on isometric muscle strength, with beneficial effects in obese individuals (N=93) at knee flexion 90° (p=0.04), and adverse effects in non-obese individuals (N=167) at handgrip (p=0.02), knee extension 60° (p=0.03) and knee flexion 60° (p<0.01). Conclusion Overall, short-term treatment with moderate to high daily doses of vitamin D did not affect muscle health or QoL. A potential beneficial effect was present on muscle strength in severe obese individuals and on QoL in vitamin D deficient individuals. Subgroup analyses however suggested negative effects of large relative increases in p-25(OH)D.

Simulated hemiparesis increases optimal spatiotemporal gait asymmetry but not metabolic cost

Several neuromuscular impairments, such as weakness (hemiparesis), occur after an individual has a stroke, and these impairments primarily affect one side of the body more than the other. Predictive musculoskeletal modeling presents an opportunity to investigate how a specific impairment affects gait performance post-stroke. Therefore, our aim was to use to predictive simulation to quantify the spatiotemporal asymmetries and changes to metabolic cost that emerge when muscle strength is unilaterally reduced. We also determined how forced spatiotemporal symmetry affects metabolic cost. We modified a 2-D musculoskeletal model by uniformly reducing the peak isometric muscle force in all muscles unilaterally. We then solved optimal control simulations of walking across a range of speeds by minimizing the sum of the cubed muscle excitations across all muscles. Lastly, we ran additional optimizations to test if reducing spatiotemporal asymmetry would result in an increase in metabolic cost. Our results showed that the magnitude and direction of effort-optimal spatiotemporal asymmetries depends on both the gait speed and level of weakness. Also, the optimal metabolic cost of transport was 1.25 m/s for the symmetrical and 20% weakness models but slower (1.00 m/s) for the 40% and 60% weakness models, suggesting that hemiparesis can account for a portion of the slower gait speed seen in people post-stroke. Adding spatiotemporal asymmetry to the cost function resulted in small increases (~4%) in metabolic cost. Overall, our results indicate that spatiotemporal asymmetry may be optimal for people post-stroke, who have asymmetrical neuromuscular impairments. Additionally, the effect of speed and level of weakness on spatiotemporal asymmetry may explain the well-known heterogenous distribution of spatiotemporal asymmetries observed in the clinic. Future work could extend our results by testing the effects of other impairments on optimal gait strategies, and therefore build a more comprehensive understanding of the gait patterns in people post-stroke.

Respiratory Responses to Short Term Sustained Isometric Muscle Contraction among Undergraduates

Aim: This study sets out to investigate whether a short-term isometric abdominal exercise can benefit adults with improvement in ventilatory functions. Materials And Methods: The present study was performed in 20 adults from the student population of I-BDS students with no history of smoking and respiratory illness. The participants did a daily 20-minute static abdominal exercise over a period of three days. The lung function test was assessed using spirometry and the values of FVC, FEV1, FEV1/FVC, PEFR, FEF 25-75. Paired dependent t test was done to evaluate the anthropometric variables and changes in lung functions pre-exercise on day 1 and post-isometric exercise on day 3. Results: The study demonstrated a significant increase in the mean values of forced vital capacity and forced expiratory volume in one second. The FEV1/FVC ratio, PEFR, FEF 25-75% did not reveal significant changes. Conclusion: The study concluded an innovative finding that ventilatory functions improved after short term isometric training.

Muscle Oxygenation Level Might Trigger the Regulation of Capillary Venous Blood Filling during Fatiguing Isometric Muscle Actions

The regulation of oxygen and blood supply during isometric muscle actions is still unclear. Recently, two behavioral types of oxygen saturation (SvO2) and relative hemoglobin amount (rHb) in venous microvessels were described during a fatiguing holding isometric muscle action (HIMA) (type I: nearly parallel behavior of SvO2 and rHb; type II: partly inverse behavior). The study aimed to ascertain an explanation of these two regulative behaviors. Twelve subjects performed one fatiguing HIMA trial with each arm by weight holding at 60% of the maximal voluntary isometric contraction (MVIC) in a 90° elbow flexion. Six subjects additionally executed one fatiguing PIMA trial by pulling on an immovable resistance with 60% of the MVIC with each side and same position. Both regulative types mentioned were found during HIMA (I: n = 7, II: n = 17) and PIMA (I: n = 3, II: n = 9). During the fatiguing measurements, rHb decreased initially and started to increase in type II at an average SvO2-level of 58.75 ± 2.14%. In type I, SvO2 never reached that specific value during loading. This might indicate the existence of a threshold around 59% which seems to trigger the increase in rHb and could explain the two behavioral types. An approach is discussed to meet the apparent incompatibility of an increased capillary blood filling (rHb) despite high intramuscular pressures which were found by other research groups during isometric muscle actions.

Kinesio Taping Relieves Pain and Improves Isokinetic Not Isometric Muscle Strength in Patients with Knee Osteoarthritis—A Systematic Review and Meta-Analysis

This study investigated the effects of kinesio taping (KT) or KT plus conventional therapy on pain, muscle strength, funrefction, and range of motion in patients with knee osteoarthritis (OA). Data sources: Databases included PubMed, Ovid Medline, CINAHL, Airiti Library, EMBASE, and WOS search engines. Search terms related to KT and knee OA were combined and searched. Articles that met the inclusion criteria and were graded with a Jadad score ≥3 were included in a meta-analysis to calculate the total effect. The exclusion criteria were non-English-language articles, non-original articles, non-full-text articles, no description of the intervention, or articles with a Jadad score ≤2. Eleven articles were included in the meta-analysis. KT treatment had a significant small total effect on pain reduction (p < 0.001; n = 1509; standardized mean difference (SMD) = −0.42; 95% CI = −0.65 to −0.18) and a significant moderate total effect on isokinetic muscle strength improvement (p = 0.001; n = 447; SMD = 0.72; 95% CI = 0.28 to 1.16). No significant total effects of KT on isometric muscle strength, time to complete functional tasks, or ROM improvement were found. KT or KT plus conventional therapy has a significant effect on pain relief and isokinetic but not isometric muscle strength improvement in patients with knee OA. KT can be an effective tool for treating knee OA pain and is especially valuable for aiding in isokinetic muscle strength. (PROSPERO register ID: CRD42021252313)

Muscle strength evaluation of limb dominance in prepubescent swimmers boys and girls

Background: The aim of this study was to compare the lower limb muscle strength in terms of gender and limb dominancy in prepubescent swimmers. Material and Methods: Seventy-four prepubescent swimmers (mean age: 11.01±1.58 years; 42 boys; 32 girls) who were training for at least 8 hours a week and without current lower limb pain participated in the study. Isometric muscle strength of lower limb was measured by hand-held dynamometry. Independent samples-t test was used to determine the difference between genders, while paired samples-t test was used for dominant-nondominant side comparison. The significance level was accepted as p<0.05. Results: Knee flexion (p<0.001), extension (p<0.001) and ankle dorsiflexion (p=0.003) muscle strength were stronger on the dominant side than on the non-dominant side. Knee flexion/extension strength ratio was similar (p=0.957); while ankle plantar flexion/dorsiflexion strength ratio was significantly different (p=0.011). Boys swimmers had stronger isometric muscle strength in the dominant side together with knee flexion (p=0.018) and knee flexion extension strength ratio (p=0.007) than girls swimmers. Conclusion: Boys swimmers had higher dominant side knee flexion muscle strength compared to female peers. Gender and lower limb dominancy might be important for lower limb muscle strength to show varieties in prepubescent swimmers before planning a training program.

Minimal graft site morbidity using autogenous semitendinosus graft from the uninjured leg: a randomised controlled trial

Purpose To quantify the effect on strength of semitendinosus (ST) graft harvest by comparing isokinetic and isometric muscle strength. Methods A cohort of 140 patients underwent anterior cruciate ligament (ACL) reconstruction (ACLR) and were randomized to ipsilateral or contralateral ST graft harvest. Isokinetic and isometric muscle strength testing using a dynamometer were collected for the operated and non-operated leg. Patients were assessed pre-surgery and at 6, 12 and 24 months after reconstruction. Results ST graft harvest reduced isokinetic flexion muscle strength for 6 months. At 12 months follow up there was no significant difference between the two groups and they were all stronger than pre-injury. No other significant differences were found in any primary or secondary outcome measurements. Conclusion Solitary ST graft harvest does not appear to result in a permanent reduced isometric or isokinetic quadriceps muscle strength on the side where the graft is harvested. A reduction in hamstring muscle strength of less than 10% can be seen at short-term follow-up with full recovery by 12 months. Most patients report little or no donor site pain. Given these findings, ST autograft is an alternative graft choice that could be used for various reconstructions in terms of donor site morbidity. Level of evidence Level II.