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The Acute Effects of Prolonged Uninterrupted Sitting on Vascular Function: A Systematic Review and Meta-analysis.
Taylor, FC, Pinto, AJ, Maniar, N, Dunstan, DW, Green, DJ
Medicine and science in sports and exercise. 2022;(1):67-76
Abstract
OBJECTIVE This study aimed to determine the dose-response relationship between prolonged sitting and vascular function in healthy individuals and those with metabolic disturbances and to investigate the acute effects, on vascular function, of interventions that target interrupting prolonged sitting. DESIGN This is a systematic review with meta-analysis. DATA SOURCES Ovid Embase, Ovid Medline, PubMed, and CINAHL were searched from inception to 4 December 2020. ELIGIBILITY CRITERIA Randomized crossover trials, quasi-randomized trials, and parallel group trials where vascular function (flow-mediated dilation [FMD]) was assessed before and after an acute period of sedentary behavior was used in this study. RESULTS Prolonged sitting resulted in a significant decrease in the standardized mean change (SMC) for lower-limb FMD at the 120-min (SMC = -0.85, 95% confidence interval [CI] = -1.32 to -0.38) and 180-min (SMC = -1.18, 95% CI = -1.69 to -0.66) time points. A similar pattern was observed for lower-limb shear rate. No significant changes were observed for any outcomes in the upper limb. Subgroup analysis indicated that prolonged sitting decreased lower-limb FMD in healthy adults (SMC = -1.33, 95% CI = -1.89 to -0.78) who had higher a priori vascular endothelial function, but not in those with metabolic and vascular dysfunction (SMC = -0.51, 95% CI = -1.18 to 0.15). Interrupting sitting with active interruptions increased the standardized mean difference for FMD, relative to prolonged sitting, but it was not statistically significant (0.13, 95% CI = -0.20 to 0.45). CONCLUSIONS Lower-limb vascular function is progressively impaired as a consequence of prolonged sitting, up to 180 min. A similar trend was not observed in upper-limb vascular function. Subgroup analysis indicated that prolonged sitting negatively affects healthy populations, a finding not observed in those with metabolic disturbances. Regularly interrupting sitting with activity may be beneficial for those with metabolic disturbances.
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2.
Effect of Strength Training on Biomechanical and Neuromuscular Variables in Distance Runners: A Systematic Review and Meta-Analysis.
Trowell, D, Vicenzino, B, Saunders, N, Fox, A, Bonacci, J
Sports medicine (Auckland, N.Z.). 2020;(1):133-150
Abstract
BACKGROUND Concurrent strength and endurance (CSE) training improves distance running performance more than endurance training alone, but the mechanisms underpinning this phenomenon are unclear. It has been hypothesised that biomechanical or neuromuscular adaptations are responsible for improvements in running performance; however, evidence on this topic has not been synthesised in a review. OBJECTIVE To evaluate the effect of CSE training on biomechanical and neuromuscular variables in distance runners. METHODS Seven electronic databases were searched from inception to November 2018 using key terms related to running and strength training. Studies were included if the following criteria were met: (1) population: 'distance' or 'endurance' runners of any training status; (2) intervention: CSE training; (3) comparator: running-only control group; (4) outcomes: at least one biomechanical or neuromuscular variable; and, (5) study design: randomised and non-randomised comparative training studies. Biomechanical and neuromuscular variables of interest included: (1) kinematic, kinetic or electromyography outcome measures captured during running; (2) lower body muscle force, strength or power outcome measures; and (3) lower body muscle-tendon stiffness outcome measures. Methodological quality and risk of bias for each study were assessed using the PEDro scale. The level of evidence for each variable was categorised according to the quantity and PEDro rating of the included studies. Between-group standardised mean differences (SMD) with 95% confidence intervals (95% CI) were calculated for studies and meta-analyses were performed to identify the pooled effect of CSE training on biomechanical and neuromuscular variables. RESULTS The search resulted in 1578 potentially relevant articles, of which 25 met the inclusion criteria and were included. There was strong evidence that CSE training significantly increased knee flexion (SMD 0.89 [95% CI 0.48, 1.30], p < 0.001), ankle plantarflexion (SMD 0.74 [95% CI 0.21-1.26], p = 0.006) and squat (SMD 0.63 [95% CI 0.13, 1.12], p = 0.010) strength, but not jump height, more than endurance training alone. Moderate evidence also showed that CSE training significantly increased knee extension strength (SMD 0.69 [95% CI 0.29, 1.09], p < 0.001) more than endurance training alone. There was very limited evidence reporting changes in stride parameters and no studies examined changes in biomechanical and neuromuscular variables during running. CONCLUSIONS Concurrent strength and endurance training improves the force-generating capacity of the ankle plantarflexors, quadriceps, hamstrings and gluteal muscles. These muscles support and propel the centre of mass and accelerate the leg during running, but there is no evidence to suggest these adaptations transfer from strength exercises to running. There is a need for research that investigates changes in biomechanical and neuromuscular variables during running to elucidate the effect of CSE training on run performance in distance runners.
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3.
Effect of vitamin D supplementation on upper and lower limb muscle strength and muscle power in athletes: A meta-analysis.
Zhang, L, Quan, M, Cao, ZB
PloS one. 2019;(4):e0215826
Abstract
BACKGROUND Vitamin D may play a role in skeletal muscle because of the discovery of VDR in skeletal muscle. However, vitamin D deficiency is a global problem, including athletes. Studies examining the effect of vitamin D supplementation on muscle function in athletes have inconsistent results. Therefore, we aimed to quantitatively summarize the evidence for the effect of vitamin D supplementation on skeletal muscle strength and explosive power of athletes using a meta-analysis. METHODS PubMed, EMBASE, Cochrane Library, and Web of Science were searched for studies to identify randomized controlled trials or controlled trials meeting the inclusion criteria. By a meta-analysis, effect sizes (standardized mean differences, SMD) with 95% confidence intervals (CI) was calculated to compare reported outcomes across studies, I2 index was used to assessing heterogeneity, and heterogeneity factors were identified by regression analysis. The potential publication and sensitivity analyses were also assessed. RESULTS Eight RCTs involving 284 athletes were included. The protocols used to evaluate the muscle strength of athletes were inconsistent across the included studies, and muscle explosive power was assessed via vertical jump tests. The results indicated that vitamin D supplementation had no impact on overall muscle strength outcomes (SMD 0.05, 95% CI: -0.39 to 0.48, p = 0.84). In subgroup analysis, vitamin D supplementation had an effect on lower-limb muscle strength (SMD 0.55, 95% CI:0.12 to 0.98, p = 0.01) but not upper-limb muscle strength (SMD -0.19, 95% CI:-0.73 to 0.36, p = 0.50) or muscle explosive power (SMD 0.05, 95% CI:-0.24 to 0.34, p = 0.73). Vitamin D supplementation was more effective for athletes trained indoors (SMD 0.48, 95% CI:0.06 to 0.90, p = 0.02). CONCLUSIONS Vitamin D supplementation positively affected lower limb muscle strength in athletes, but not upper limb muscle strength or muscle power. Different muscle groups and functions may respond differently to vitamin D supplementation. Additional studies should focus on determining the appropriate vitamin D supplementation methods and optimal serum 25(OH)D levels for athletes. REGISTRATION The protocol for our study is registered in the international prospective register of systematic reviews (PROSPERO registration number CRD42016045872).
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4.
Threshold of Energy Deficit and Lower-Body Performance Declines in Military Personnel: A Meta-Regression.
Murphy, NE, Carrigan, CT, Philip Karl, J, Pasiakos, SM, Margolis, LM
Sports medicine (Auckland, N.Z.). 2018;(9):2169-2178
Abstract
BACKGROUND Negative energy balance (EB) is common during military operations, diminishing body mass and physical performance. However, the magnitude of negative EB where performance would still be maintained is not well defined. OBJECTIVE Our objective was to explore relationships between EB and physical performance during military operations and define an acceptable negative EB threshold where performance may be maintained. METHODS A systematic search was performed for studies that measured EB and physical performance during military training. A total of 632 articles and technical reports were screened. Lower-body power and strength were the most common performance tests across investigations and were used as physical performance outcomes. Data were extracted from nine eligible studies containing 15 independent subgroups. Meta-regression assessed changes in performance in relation to study duration (days), average daily EB, and total EB (daily EB × duration). RESULTS Changes in physical performance were not associated with average daily EB or training duration. Total EB was associated with changes in lower-body power (r2 = 0.764, P < 0.001) and strength (r2 = 0.836, P < 0.001) independently and combined (r2 = 0.454, P = 0.002). Predictive equations generated from the meta-regression indicated that, for a zero to small (2%) decline in performance, total EB should be limited to - 5686 to - 19,109 kcal, for an entire operation, whereas total EB of - 39,243 to - 59,377 kcal will result in moderate (7%) to large (10%) declines in performance. CONCLUSION These data demonstrated that greater total negative EB is associated with declines in lower-body performance during military operations.
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5.
Prevention of exertional lower body musculoskeletal injury in tactical populations: protocol for a systematic review and planned meta-analysis of prospective studies from 1955 to 2018.
Flanagan, SD, Sinnott, AM, Krajewski, KT, Johnson, CD, Eagle, SR, LaGoy, AD, Beckner, ME, Beethe, AZ, Turner, R, Lovalekar, M, et al
Systematic reviews. 2018;(1):73
Abstract
BACKGROUND Exertional lower body musculoskeletal injuries (ELBI) cost billions of dollars and compromise the readiness and job performance of military service and public safety workers (i.e., tactical populations). The prevalence and burden of such injuries underscores the importance of prevention efforts during activities necessary to sustain core occupational competencies. Attempts to synthesize prevention techniques specific to tactical populations have provided limited insight on the comparative efficacy of interventions that do not modify physical training practices. There is also a need to assess the influence of sex, exposure, injury classification scheme, and study design. Thus, the primary purpose of the systematic review and planned meta-analysis detailed in this protocol is to evaluate the comparative efficacy of ELBI prevention strategies in tactical populations. METHODS A systematic search strategy will be implemented in MEDLINE, EMBASE, Cochrane, and CINAHL. A multi-tiered process will be used to capture randomized controlled trials and prospective cohort studies that directly assess the prevention of ELBI in tactical population(s). Extracted data will be used to compare prevention strategies and assess the influence of heterogeneity related to occupation, sex, exposure, injury characteristics, and study quality. In addition, individual risk of bias, meta-bias, and the quality of the body of evidence will be rigorously tested. DISCUSSION This systematic review and planned meta-analysis will comprehensively evaluate ELBI mitigation strategies in tactical populations, elucidate factors that influence responses to treatment, and assess the overall quality of the body of research. Results of this work will guide the prioritization of ELBI prevention strategies and direct future research efforts, with direct relevance to tactical, health and rehabilitation science, and human performance optimization stakeholders. SYSTEMATIC REVIEW REGISTRATION The systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 3 Jan 2018 (registration number CRD42018081799 ).
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6.
A Systematic Review and Meta-Analysis of Nutritional Supplementation in Chronic Lower Extremity Wounds.
Ye, J, Mani, R
The international journal of lower extremity wounds. 2016;(4):296-302
Abstract
A systematic review and meta-analyses of nutritional supplementation to treat chronic lower extremity wounds was done in order to test the premise that impaired nutrition is implicated in healing. The databases of Ovid MEDLINE, Ovid EMBASE, Cochrane Library, and EBSCO CINAHL (1972-October 2014) were searched systematically. Only randomized controlled trials in adults with chronic lower extremity wounds were included. Both topical and systemic routes of supplementing nutrition were considered. The primary outcome was wound healing. Study characteristics, outcomes, and risk of bias were extracted by trained researchers and confirmed by the principal investigator. Twenty-three of 278 (8.3%) retrieved articles met the inclusion criteria and were selected. Most of the studies were of unclear or low risk. Overall, nutritional supplementation was favorable (risk ratio [RR] = 1.44, 95% confidence interval [CI] = 1.25-1.66). The systemic route was marginally better than the topical one (RR = 1.51, 95% CI = 1.36-1.67; RR = 1.14, 95% CI = 0.96-1.36, respectively). For venous ulcers, the data showed nutritional supplementation to be significantly beneficial compared to placebo (RR = 1.44, 95% CI = 1.31-1.59). Similar data were found for diabetic foot and sickle cell ulcers (RR = 1.17, 95% CI = 0.93-1.47; RR = 1.56, 95% CI = 0.94-2.60, respectively). These data permit the inferences that nutritional supplementation in the populations studied showed significant benefits in the healing of venous ulcers and tendency (nonsignificant trends) in the healing of diabetic and sickle cell ulcers.