Category:
Sports; Ankle
Introduction/Purpose:
In general, Static Stretching (SS) is widely used during warm-ups and cool-downs at competitive practices and events. Previous studies have shown that SS ...have improved muscle stiffness. On the other hand, previous studies have not shown range of motion, or vertical jump. Recently, acute effects of Cyclic Stretching (CS) have suggested to improve muscle stiffness and dynamic balance. CS is moved at a constant speed and angle using continuous passive and dynamometer-equipped exercise equipment. However, long-term CS and SS programs have been shown to improve muscle stiffness, hardness, and It is not known if muscle strength or physical performance is altered. This study aimed to examine the effects of a 4-week CS and SS program on muscle stiffness and hardness, muscle strength, and jump performance.
Methods:
The subjects participated 18 healthy men and were randomly assigned to a CS or SS group. Each stretching program was stretched in each condition for 2 minutes in a standing position in 5 days a week for 4 weeks. To assess muscle stiffness, muscle- tendon junction (MTJ) displacement and MTJ angle of gastrocnemius medialis (MG) were measured using ultrasonography and 20° before (pre-training) and after (post-training) conducting CS and SS program. MG hardness was measured using ultrasound real- time tissue elastography (RTE). ROM max and normalized peak torque (NPT) of ankle plantar flexor, squat jump (SJ) performance were measured in the pre- and post-training. The effects of the intervention on all outcome measures were determined using 2- way repeated-measures ANOVA with two group as a between participants factor and time (pre-training, post-training) When interaction effects were detected, post hoc comparisons were performed to test the differences in physical variables between pre- and post-training.
Results:
ROM max was significantly affected by time between CS and SS program (P < .001, F = 26.0). MTJ displacement from 0°to 20°were significantly affected by time (P < .05, F = 5.49; P < .01, F = 10.26; P < .01, F = 9.74). RTE from 0°to 20°were significantly affected by time (P < .01, F = 13.27; P < .01, F = 8.33; P < .01, F = 53.52). There was significantly interaction for NPT between CS and SS program (P < .01, F = 4.80). SJ were significantly affected by time (P < .05, F = 5.70).
Conclusion:
This study examined the long-term effect of CS and SS on ROM max, muscle stiffness, NPT, and SJ. The results indicate that CS training had greater improvement than SS training in muscle strength between pre- and post-training. A significant decrease in muscle stiffness and hardness after SS was observed compared with CS. However, CS not only improves muscle stiffness and hardness as shown the effect of SS but also suggests the possibility of being a new extension method to improve muscle strength.
Introduction: Periodic testing is essential to evaluate changes in key physical and physiological characteristics in response to development strategies employed with adolescent rugby league players; ...however, the retest reliability of scientifically popular tests to assess these characteristics are yet to be comprehensively examined in this population. ...the aim of this study was to determine the retest reliability of the most commonly used tests in the literature, to assess key physical and physiological characteristics in adolescent, male rugby league players. Tests used to assess physiological characteristics demonstrated moderate to excellent ICC, with CV <5% including: linear speed, ICC=0.794, CV=1.35%; change-of-direction speed, ICC=0.787–0.860, CV=1.85–2.07%; aerobic capacity, ICC=0.854, CV=3.42%; muscular power, ICC=0.733–0.874, CV=3.72–4.02%; and muscular strength, ICC=0.944–0.988, CV=1.08–2.56%.
The aim of this study was to evaluate the criterion validity of the IHT and the SLHB against isokinetic dynamometry, and to assess the test-retest reliability of the IHT and the SLHBT. Methods: The ...study employed a cross-sectional criterion validity and test-retest reliability design. Test-retest reliability was determined using intraclass correlation (ICC2,1 model).
Hand-held dynamometry (HHD) has never previously been used to examine isometric muscle power. Rate of force development (RFD) is often used for muscle power assessment, however no consensus currently ...exists on the most appropriate method of calculation. The aim of this study was to examine the reliability of different algorithms for RFD calculation and to examine the intra-rater, inter-rater, and inter-device reliability of HHD as well as the concurrent validity of HHD for the assessment of isometric lower limb muscle strength and power.
30 healthy young adults (age: 23±5 yrs, male: 15) were assessed on two sessions. Isometric muscle strength and power were measured using peak force and RFD respectively using two HHDs (Lafayette Model-01165 and Hoggan microFET2) and a criterion-reference KinCom dynamometer. Statistical analysis of reliability and validity comprised intraclass correlation coefficients (ICC), Pearson correlations, concordance correlations, standard error of measurement, and minimal detectable change.
Comparison of RFD methods revealed that a peak 200 ms moving window algorithm provided optimal reliability results. Intra-rater, inter-rater, and inter-device reliability analysis of peak force and RFD revealed mostly good to excellent reliability (coefficients ≥ 0.70) for all muscle groups. Concurrent validity analysis showed moderate to excellent relationships between HHD and fixed dynamometry for the hip and knee (ICCs ≥ 0.70) for both peak force and RFD, with mostly poor to good results shown for the ankle muscles (ICCs = 0.31-0.79).
Hand-held dynamometry has good to excellent reliability and validity for most measures of isometric lower limb strength and power in a healthy population, particularly for proximal muscle groups. To aid implementation we have created freely available software to extract these variables from data stored on the Lafayette device. Future research should examine the reliability and validity of these variables in clinical populations.
We systemically reviewed the literature to assess how long-term testosterone suppressing gender-affirming hormone therapy influenced lean body mass (LBM), muscular area, muscular strength and ...haemoglobin (Hgb)/haematocrit (HCT).
Systematic review.
Four databases (BioMed Central, PubMed, Scopus and Web of Science) were searched in April 2020 for papers from 1999 to 2020.
Eligible studies were those that measured at least one of the variables of interest, included transwomen and were written in English.
Twenty-four studies were identified and reviewed. Transwomen experienced significant decreases in all parameters measured, with different time courses noted. After 4 months of hormone therapy, transwomen have Hgb/HCT levels equivalent to those of cisgender women. After 12 months of hormone therapy, significant decreases in measures of strength, LBM and muscle area are observed. The effects of longer duration therapy (36 months) in eliciting further decrements in these measures are unclear due to paucity of data. Notwithstanding, values for strength, LBM and muscle area in transwomen remain above those of cisgender women, even after 36 months of hormone therapy.
In transwomen, hormone therapy rapidly reduces Hgb to levels seen in cisgender women. In contrast, hormone therapy decreases strength, LBM and muscle area, yet values remain above that observed in cisgender women, even after 36 months. These findings suggest that strength may be well preserved in transwomen during the first 3 years of hormone therapy.
Low muscle strength is an important heritable indicator of poor health linked to morbidity and mortality in older people. In a genome-wide association study meta-analysis of 256,523 Europeans aged 60 ...years and over from 22 cohorts we identify 15 loci associated with muscle weakness (European Working Group on Sarcopenia in Older People definition: n = 48,596 cases, 18.9% of total), including 12 loci not implicated in previous analyses of continuous measures of grip strength. Loci include genes reportedly involved in autoimmune disease (HLA-DQA1 p = 4 × 10
), arthritis (GDF5 p = 4 × 10
), cell cycle control and cancer protection, regulation of transcription, and others involved in the development and maintenance of the musculoskeletal system. Using Mendelian randomization we report possible overlapping causal pathways, including diabetes susceptibility, haematological parameters, and the immune system. We conclude that muscle weakness in older adults has distinct mechanisms from continuous strength, including several pathways considered to be hallmarks of ageing.
The purpose of this study was to critically appraise and summarize the evidence for reliability of muscle strength and muscle power assessment in patients with neuromuscular diseases (NMDs) using ...isokinetic dynamometry.
PubMed, CINAHL, and Embase electronic databases were searched from inception to March 8, 2022. Studies designed to evaluate reliability of muscle strength and power measurements using isokinetic dynamometry were included in this review. First, the methodological quality of the studies was assessed according to the Consensus-Based Standards for the Selection of Health Measurement Instruments guidelines. Next, the quality of measurement properties was determined. Finally, the methodological quality and quality of measurement properties of the studies were combined to obtain a best-evidence synthesis.
A best-evidence synthesis of reliability was performed in 11 studies including postpoliomyelitis syndrome (n = 5), hereditary motor and sensory neuropathy (n = 2), motor neuron diseases (n = 1), myotonic dystrophy (n = 1), and groups of pooled NMDs (n = 2). A best-evidence synthesis on measurement error could not be performed. Quality of evidence on reliability ranged from high in postpoliomyelitis syndrome to very low in hereditary motor and sensory neuropathy, motor neuron diseases, and groups of pooled NMDs. The most frequently used outcome measure was peak torque, which was reliable in all populations (intraclass correlation coefficient >0.7).
The quality of evidence for reliability of isokinetic dynamometry was found to vary substantially among different NMDs. High quality of evidence has been obtained only in patients with postpoliomyelitis syndrome. Further research is needed in the majority of known NMDs to determine reliability and validity of isokinetic dynamometry.
The ability of isokinetic dynamometers to capture clinically relevant changes in muscle strength and muscle power in NMDs remains unclear. Isokinetic dynamometry results in NMDs should be interpreted with caution.
PurposeTo investigate early structural and mechanical predictors of plantarflexor muscle strength and the magnitude of Achilles tendon (AT) nonuniform displacement at 6 and 12 months after AT ...rupture.MethodsThirty‐five participants (28 males and 7 females; mean ± SD age 41.7 ± 11.1 years) were assessed for isometric plantarflexion maximal voluntary contraction (MVC) and AT nonuniformity at 6 and 12 months after rupture. Structural and mechanical AT and plantarflexor muscle properties were measured at 2 months. Limb asymmetry index (LSI) was calculated for all variables. Multiple linear regression was used with the 6 and 12 month MVC LSI and 12 month AT nonuniformity LSI as dependent variables and AT and plantarflexor muscle properties at 2 months as independent variables. The level of pre‐ and post‐injury sports participation was inquired using Tegner score at 2 and 12 months (scale 0–10, 10 = best possible score). Subjective perception of recovery was assessed with Achilles tendon total rupture score (ATRS) at 12 months (scale 0–100, 100=best possible score).ResultsAchilles tendon resting angle (ATRA) symmetry at 2 months predicted MVC symmetry at 6 and 12 months after rupture (β = 2.530, 95% CI 1.041–4.018, adjusted R2 = 0.416, p = 0.002; β = 1.659, 95% CI 0.330–2.988, adjusted R2 = 0.418, p = 0.016, respectively). At 12 months, participants had recovered their pre‐injury level of sports participation (Tegner 6 ± 2 points). The median (IQR) ATRS score was 92 (7) points at 12 months.ConclusionGreater asymmetry of ATRA in the early recovery phase may be a predictor of plantarflexor muscle strength deficits up to 1 year after rupture.Trial Registration: This research is a part of “nonoperative treatment of Achilles tendon rupture in Central Finland: a prospective cohort study” that has been registered in ClinicalTrials.gov (NCT03704532)
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