Variability between Different Hand-Held Dynamometers for Measuring Muscle Strength.

Muscle strength is routinely measured in patients with neuromuscular disorders by hand-held dynamometry incorporating a wireless load cell to evaluate disease severity and therapeutic efficacy, with magnitude of effect often based on normative reference values. While several hand-held dynamometers exist, their interchangeability is unknown which limits the utility of normative data. We investigated the variability between six commercially available dynamometers for measuring the isometric muscle strength of four muscle groups in thirty healthy individuals. Following electro-mechanical sensor calibration against knowns loads, Citec, Nicholas, MicroFET2, and Commander dynamometers were used to assess the strength of ankle dorsiflexors, hip internal rotators, and shoulder external rotators. Citec, Jamar Plus, and Baseline Hydraulic dynamometers were used to capture hand grip strength. Variability between dynamometers was represented as percent differences and statistical significance was calculated with one-way repeated measures ANOVA. Percent differences between dynamometers ranged from 0.2% to 16%. No significant differences were recorded between the Citec, Nicholas, and MicroFET2 dynamometers (p > 0.05). Citec grip strength measures differed to the Jamar Plus and Baseline Hydraulic dynamometers (p < 0.01). However, when controlling for grip circumference, they were comparable (p > 0.05). Several hand-held dynamometers can be used interchangeably to measure upper and lower limb strength, thereby maximising the use of normative reference values.

An in-depth analysis of wound incidence and injury status among professional athletes: A comprehensive review.

This review aims to synthesize current knowledge on the incidence, characteristics and management of wounds and injuries among professional ice hockey athletes, with the specific focus on the emerging population of Chinese female players. An extensive literature search was conducted across several databases to gather data on injury patterns and wounds, causes, severity and prevention strategies in ice hockey. Special attention was given to studies involving female athletes and unique challenges faced by players in developing regions like China. The review also examined the impact of training modalities, protective equipment and medical interventions on injury rates. The findings reveal a significant seasonal fluctuation in wound incidence, with marked reduction following the preseason period. This trend underscores the effectiveness of adjusted training programmes and essential role of medical teams in injury prevention and rehabilitation. Analysis did not show significant difference in wound rates between technical and physical training sessions, suggesting that injuries are pervasive risk across all training activities. Skating, collisions and inadequate warm-ups were identified as the leading causes of wounds, highlighting areas for targeted preventive measures. The distribution of wounds across various body regions pointed to knee, lower back and wrist as the most vulnerable sites, necessitating focused protection and training adjustments. Ice hockey, particularly among female athletes in China, presents complex injury landscape characterized by the wide range of wounds. The study emphasizes the necessity of comprehensive, multidisciplinary approach to injury prevention that includes training modifications, enhanced protective gear and strategic medical oversight. By addressing the specific causes and patterns of injuries identified, stakeholders can better protect athletes from the inherent risks of the sport, promote safer play and extend career longevity.

Despite reductions in muscle mass and muscle strength in adults with CHD, the muscle strength per muscle mass relationship does not differ from controls.

BACKGROUND: Patients with CHD exhibit reduced isometric muscle strength and muscle mass; however, little is known how these parameters relate. Therefore, the aim was to investigate the relation between isometric limb muscle strength and muscle mass for patients in comparison to age- and sex-matched control subjects. METHODS: Seventy-four patients (35.6 ± 14.3 years, women n = 22) and 74 matched controls were included. Isometric muscle strength in elbow flexion, knee extension, and hand grip was assessed using dynamometers. Lean mass, reflecting skeletal muscle mass, in the arms and legs was assessed with dual-energy x-ray absorptiometry. RESULTS: Compared to controls, patients had lower muscle strength in elbow flexion, knee extension, and hand grip, and lower muscle mass in the arms (6.6 ± 1.8 kg versus 5.8 ± 1.7 kg, p < 0.001) and legs (18.4 ± 3.5 kg versus 15.9 ± 3.2 kg, p < 0.001). There was no difference in achieved muscle force per unit muscle mass in patients compared to controls (elbow flexion 0.03 ± 0.004 versus 0.03 ± 0.005 N/g, p = 0.5; grip strength 0.008 ± 0.001 versus 0.008 ± 0.001 N/g, p = 0.7; knee extension 0.027 ± 0.06 versus 0.028 ± 0.06 N/g, p = 0.5). For both groups, muscle mass in the arms correlated strongly with muscle strength in elbow flexion (patients r = 0.86, controls, r = 0.89), hand grip (patients, r = 0.84, controls, r = 0.81), and muscle mass in the leg to knee extension (patients r = 0.64, controls r = 0.68). CONCLUSION: The relationship between isometric muscle strength and limb muscle mass in adults with CHD indicates that the skeletal muscles have the same efficiency as in healthy controls.

The Acute and Prolonged Effects of Different Durations of Foam Rolling on Range of Motion, Muscle Stiffness, and Muscle Strength.

"Foam Rolling" has been used in sports settings to increase range of motion and decrease muscle stiffness without decreasing muscle strength and athletic performance. However, there has been no study investigating the acute and prolonged effect of different durations of foam rolling intervention on muscle stiffness, and the minimum foam rolling intervention duration required to decrease muscle stiffness is unclear. Therefore, the purpose of this study was to investigate the acute and prolonged effect of different durations of foam rolling intervention on ROM, muscle stiffness, and muscle strength. The 45 participants were randomly allocated to 1 of 3 groups (30 s × 1 times group vs 30 s × 3 times group vs 30 s× 10 times group). The outcome measures were dorsiflexion range of motion, shear elastic modulus of medial gastrocnemius, and muscle strength before, 2 min and 30 min after foam rolling intervention. There were no significant differences before and 2 min after foam rolling intervention in 30 s×1 time group, whereas dorsiflexion range of motion was increased in both 30 s×3 times group (p = 0.042, d = 0.26) and 30 s× 10 times group (p < 0.01, d = 0.33). However, the increase in dorsiflexion range of motion was returned to baseline value after 30 minutes in both 30 s × 3 times group and 30 s × 10 times group. In addition, there were no significant changes in shear elastic modulus and muscle strength in all groups. This study suggested that foam rolling for more than 90 s or more of foam rolling was effective in order to increase the range of motion immediately without changing muscle stiffness and muscle strength.

Impaired knee extension muscle strength in adolescents but not in children with Fontan circulation.

INTRODUCTION: Impaired isometric muscle strength was previously reported in adults with Fontan circulation. However, it is unclear if this impairment is present in children and adolescents with Fontan circulation. We investigated isometric muscle strength of the lower limb in patients (6-18 years) with Fontan circulation in comparison with healthy controls. METHOD: In this cross-sectional study, 43 patients (6-18 years) with Fontan circulation and 43 age- and sex-matched controls were included. Isometric knee extension and plantar flexion muscle strength were assessed using dynamometry (Newton, N). Lean mass of the legs was assessed with dual-energy X-ray absorptiometry. Analyses were performed on group level (n = 43), and for subgroups that included children aged 6-12 years (n = 18) and adolescents aged 13-18 years (n = 25). RESULTS: On group level, the patients with Fontan circulation had impaired isometric knee extension strength in comparison with the controls (p = 0.03). In subgroup analyses, impaired isometric knee extension strength was present in the adolescents (p = 0.009) but not in the children groups. For plantar flexion, there was no difference between patients and controls. There was no difference in lean mass between patients and controls (9.6 ± 4.3 kg vs. 10.8 ± 5.6 kg, p = 0.31). However, the lean mass was highly correlated to isometric knee extension strength (patients r = 0.89, controls r = 0.96, p < 0.001) and isometric plantar flexion strength (patients r = 0.7, controls r = 0.81, p < 0.001). CONCLUSION: The finding of impaired isometric knee extension muscle strength in adolescents (13-18 years) with Fontan circulation and no corresponding impairment in the children group (6-12 years) could imply that isometric muscle strength gets more impaired with age.

Elbow flexion and forearm supination strength in a healthy population.

BACKGROUND AND HYPOTHESIS: Despite the lack of representative data of a healthy population, many clinical trials concerning the measurement of postoperative elbow flexion or forearm supination strength use the contralateral side as a control. We hypothesized that there are no differences in elbow flexion and supination strength between the dominant and nondominant sides in healthy volunteers. METHODS: The study was performed on a cross-sectional cohort of healthy subjects without any prior injuries or surgical interventions of the upper extremities. Isometric elbow flexion strength and supination strength were measured on both the dominant and nondominant sides. The results were analyzed for the entire group and subanalyzed for female vs. male, for different age groups, and according to handedness and regular practice of overhead sports. RESULTS: A total of 150 subjects (75 female and 75 male subjects; mean age, 44 ± 15 years [range, 18-72 years]) were included in this study. Within the entire collective, no significant differences concerning the elbow flexion strength between the dominant and nondominant sides could be detected, whereas the supination strength was 7% higher on the dominant side (P = .010). Women, right-hand-dominant subjects, and subjects who do not regularly practice overhead sports have a significant 8% higher supination strength on the dominant side compared with the nondominant side (P < .05). Left-hand-dominant subjects have an 8% higher elbow flexion strength on the nondominant right side (P < .05). CONCLUSION: Elbow flexion strength and forearm supination strength differ between the dominant and nondominant sides. The contralateral upper extremity cannot be used as a matched control without some adjustments.

Estimation of 1RM for knee extension based on the maximal isometric muscle strength and body composition.

[Purpose] To create a regression formula in order to estimate 1RM for knee extensors, based on the maximal isometric muscle strength measured using a hand-held dynamometer and data regarding the body composition. [Subjects and Methods] Measurement was performed in 21 healthy males in their twenties to thirties. Single regression analysis was performed, with measurement values representing 1RM and the maximal isometric muscle strength as dependent and independent variables, respectively. Furthermore, multiple regression analysis was performed, with data regarding the body composition incorporated as another independent variable, in addition to the maximal isometric muscle strength. [Results] Through single regression analysis with the maximal isometric muscle strength as an independent variable, the following regression formula was created: 1RM (kg)=0.714 + 0.783 × maximal isometric muscle strength (kgf). On multiple regression analysis, only the total muscle mass was extracted. [Conclusion] A highly accurate regression formula to estimate 1RM was created based on both the maximal isometric muscle strength and body composition. Using a hand-held dynamometer and body composition analyzer, it was possible to measure these items in a short time, and obtain clinically useful results.

Validity and reliability of isometric muscle strength measurements of hip abduction and abduction with external hip rotation in a bent-hip position using a handheld dynamometer with a belt.

[Purpose] This study aimed to investigate the relatedness, reliability, and validity of isometric muscle strength measurements of hip abduction and abduction with an external hip rotation in a bent-hip position using a handheld dynamometer with a belt. [Subjects and Methods] Twenty healthy young adults, with a mean age of 21.5 ± 0.6 years were included. Isometric hip muscle strength in the subjects' right legs was measured under two posture positions using two devices: a handheld dynamometer with a belt and an isokinetic dynamometer. Reliability was evaluated using an intra-class correlation coefficient (ICC); relatedness and validity were evaluated using Pearson's product moment correlation coefficient. Differences in measurements of devices were assessed by two-way ANOVA. [Results] ICC (1, 1) was ≥0.9; significant positive correlations in measurements were found between the two devices under both conditions. No main effect was found between the measurement values. [Conclusion] Our findings revealed that there was relatedness, reliability, and validity of this method for isometric muscle strength measurements using a handheld dynamometer with a belt.

Effects of complex rehabilitation training on low back strength in chronic low back pain.

[Purpose] The purpose of this study was to assess the effects of complex rehabilitation training on chronic low back pain. [Subjects and Methods] Complex rehabilitation training for lumbar isometric muscle strength was conducted for 12 weeks for males (n=10) and females (n=10) with chronic low back pain, who were aged in their 30s. [Results] Isometric strength of lumbar extension was increased post-test, and significant differences were found between males and females, at MedX angle of 0, 48, and 60. [Conclusion] This study showed that complex rehabilitation training had a beneficial effect on the muscle strength of lumbar extension in patients with chronic low back pain.

The effect of thoracic spine mobilization and stabilization exercise on the muscular strength and flexibility of the trunk of chronic low back pain patients.

[Purpose] To investigate whether thoracic spine mobilization added to stabilization exercises increases the muscular strength and range of motion of the thoracic vertebrae of chronic low-back pain patients. [Subjects] This study enrolled 20 patients with chronic low back pain, who were divided into two groups. Ten subjects were randomly selected for the stabilization exercise group and the remaining 10 subjects received thoracic spine mobilization in addition to performing the stabilization exercises. [Methods] The patients performed stabilization exercises and received thoracic spine mobilization for 12 weeks. The range of motion and isometric muscular strength of the vertebrae of all subjects were measured before and after the intervention. [Results] In the comparison of muscular strength before and after the intervention, the change in muscular strength of the trunk flexors in the stabilization exercise group was 16.0±7.4 Nm, and that of the thoracic spine mobilization group was 34.2±7.6 Nm, a significant difference in each group. In the post-intervention intergroup comparison, the muscular strength of trunk flexors in the stabilization exercise group was 111.1±16.9 Nm, while that of the thoracic spine mobilization group was 125.9±11.3 Nm, a significant difference. Also, the muscular strength of the trunk extensors in the stabilization exercise group was 148.9±31.8 Nm, while that of the thoracic spine mobilization group was 182.9±37.2 Nm, a significant difference. The thoracic spine flexion in the stabilization exercise group was 29.8±9 degrees, while that of the thoracic spine mobilization group was 38.7±6.9 degrees, a significant difference. However, there was no significant difference in lumbar flexion values between the two groups. [Conclusion] Thoracic spine mobilization added to a stabilization exercise increased the muscular strength of patients with chronic low back pain.

The comparison of cross-education effect in young and elderly females from unilateral training of the elbow flexors.

BACKGROUND: Many studies have reported the increase in strength of the untrained contralateral limb after unilateral training. The aim of this study was to compare the cross education effect in the young and elderly persons. METHODS: In this quasi-experimental and pre-post study, 12 young people aged 28.25 ±3.11 years and 12 elderly persons (aged 73.08 ± 5.3 years) participated. The subjects had no history of strength training and upper limb movement impairments. Maximal isometric flexion strength in the dominant limb and the contralateral side before and after training were measured by tensiometer. Subjects performed elbow flexion exercises in the dominant side, using 3 sets of 10 repetition of the 60-70% maximal force for two weeks. Independent and paired t test were used to analyze between and within groups differences. RESULTS: The results showed that short-term isometric resistive exercise led to a significant increase of strength in trained and untrained limbs in both groups (p<0.05). There was not a significant difference between the two groups in the rate of strength increase, both in the upper limb that was exercised and also in the opposite side (p> 0.05). CONCLUSION: The increased muscle strength observed during training indicates positive effect of training in old adult. The increased muscle strength in untrained limb suggests the capacity of neuromuscular adaptation among old adults, suitable to be used in cases of limb immobility or unilateral impairment.

Study of whey protein on muscle mass and functional rehabilitation in postoperative total knee arthroplasty patients.

BACKGROUND: Patients who underwent total knee arthroplasty (TKA) often experience muscle loss due to pain and limited mobility. Nutritional supplementation and rehabilitation may positively affect the decline in muscle function. OBJECTIVE: The purpose of this study is to evaluate whether whey protein intervention, in addition to conventional rehabilitation training, is beneficial in improving muscle function and quality of life in patients after TKA. METHODS: 72 patients who met the criteria were selected for this randomized controlled study. For the experimental group, whey protein was used as a daily supplement for 12 weeks, while the control group was given a placebo, during which both groups received conventional rehabilitation training. Muscle strength and each of the secondary observables needed to be measured and statistically analyzed preoperatively and at 4, 8, and 12 weeks post-intervention. RESULTS: In total, 62 subjects completed the study: 32 in the experimental group and 30 in the control group. Both groups showed significant improvement in muscle strength, VAS, ROM, AKS and leg circumference after 12 weeks of treatment. Compared to the control group, patients in the experimental group showed significant improvement in muscle strength, VAS, ROM, AKS and leg circumference (p= 0.001, p= 0.002, p= 0.001, p= 0.001, p= 0.001, respectively) after 12 weeks of treatment. CONCLUSION: The 12-week intervention of whey protein nutritional supplement showed significant improvement in muscle mass and function among post-TKA patients besides aiding with conventional rehabilitation exercise.

Variability of unilateral and bilateral isometric muscle strength of lower extremities extensors in young females and males.

BACKGROUND: The muscle strength of the lower extremity extensors can be evaluated in the closed kinetic chain (CKC) during unilateral or bilateral conditions. Factors such as the mass and length of the muscle, joint angle, type of contraction, and gender influence the magnitude of the muscle strength. The aim of this study was to compare the isometric strength of lower extremity extensors between the different knee extension angles (KEs) as well as between bilateral and unilateral conditions. METHODS: Nineteen female students (age: 20.2 ± 0.6 years) and nineteen male students (age: 20.3 ± 0.7 years) participated in the study. The muscle strength was evaluated in CKC using the strain gauge dynamometer. The analysis included values of the maximum muscle strength normalized to body mass (MS/BM) for the six KEs of 80°, 70°, 60°, 50°, 40° and 30°. RESULTS: A significant main effect in the MS/BM values for the angle factor (p < 0.001) and condition factor (p < 0.001) was found. Moreover, there was a non-significant interaction effect between the angle factor and gender factor (p = 0.476) as well as between the condition factor and gender factor (p = 0.770). Comparisons showed significant differences in the MS/BM values between the six KEs (p < 0.001). Furthermore, significantly lower MS/BM values for bilateral conditions than unilateral conditions at the 30° KE were observed (p < 0.001). CONCLUSION: The decrease in KE by 10° significantly increased the muscle strength of the lower extremity extensors. Gender did not affect the change in MS/BM values with the change in KE and conditions. Findings also revealed significant bilateral deficit, i.e., significantly a lower summed muscle strength during bilateral conditions than unilateral conditions. The study emphasized the importance of selecting the 30° KE as the optimal angle to assess the maximum strength developed in CKC.

Range of Motion and Muscle Strength Changes in Japanese Professional Pitchers During the Baseball Season.

BACKGROUND: There are no studies examining changes in the physical function throughout the baseball season in Japanese professional players. We examined the range of motion (ROM) and muscle strength changes in professional baseball pitchers as the season progresses. MATERIALS AND METHODS: Five professional baseball pitchers were included. ROM, flexibility, and muscle strength of the trunk and shoulder, elbow, hip, knee, and ankle joints were measured pre-season (PRE), mid-season (MID), and post-season (POST). RESULTS: The total shoulder arc ROM of the dominant sides significantly decreased compared to that of the nondominant sides at MID and POST. Shoulder abduction muscle strength of the dominant sides significantly decreased at POST compared to that at PRE. In the trunk, lateral flexion ROM of bilateral sides significantly decreased at MID and POST compared to that at PRE, and the duration time of the side bridge test of the dominant sides significantly decreased at POST to that at PRE. Hip extension ROM and muscle strength and internal rotation ROM of the push-off leg significantly decreased at POST compared to that at PRE. CONCLUSION: The total shoulder arc ROM and shoulder abductor muscle strength of the dominant sides, trunk lateral flexion ROM and muscle strength, push-off leg hip joint extension muscle strength and ROM, and internal rotation ROM were more susceptible to changes as the season progressed. In order to maintain performance and prevent a throwing disorder, it is necessary to focus on these movements during the season and to appropriately train and condition these muscle groups.

Progressive resistance training for children with cerebral palsy: A randomized controlled trial evaluating the effects on muscle strength and morphology.

Children with spastic cerebral palsy often present with muscle weakness, resulting from neural impairments and muscular alterations. While progressive resistance training (PRT) improves muscle weakness, the effects on muscle morphology remain inconclusive. This investigation evaluated the effects of a PRT program on lower limb muscle strength, morphology and gross motor function. Forty-nine children with spastic cerebral palsy were randomized by minimization. The intervention group (nparticipants = 26, age: 8.3 ± 2.0 years, Gross Motor Function Classification System [GMFCS] level I/II/III: 17/5/4, nlegs = 41) received a 12-week PRT program, consisting of 3-4 sessions per week, with exercises performed in 3 sets of 10 repetitions, aiming at 60%-80% of the 1-repetition maximum. Training sessions were performed under supervision with the physiotherapist and at home. The control group (nparticipants = 22, age: 8.5 ± 2.1 year, GMFCS level I/II/III: 14/5/3, nlegs = 36) continued usual care including regular physiotherapy and use of orthotics. We assessed pre- and post-training knee extension, knee flexion and plantar flexion isometric strength, rectus femoris, semitendinosus and medial gastrocnemius muscle morphology, as well as functional strength, gross motor function and walking capacity. Data processing was performed blinded. Linear mixed models were applied to evaluate the difference in evolution over time between the control and intervention group (interaction-effect) and within each group (time-effect). The α-level was set at p = 0.01. Knee flexion strength and unilateral heel raises showed a significant interaction-effect (p ≤ 0.008), with improvements in the intervention group (p ≤ 0.001). Moreover, significant time-effects were seen for knee extension and plantar flexion isometric strength, rectus femoris and medial gastrocnemius MV, sit-to-stand and lateral step-up in the intervention group (p ≤ 0.004). Echo-intensity, muscle lengths and gross motor function showed limited to no changes. PRT improved strength and MV in the intervention group, whereby strength parameters significantly or close to significantly differed from the control group. Although, relative improvements in strength were larger than improvements in MV, important effects were seen on the maintenance of muscle size relative to skeletal growth. In conclusion, this study proved the effectiveness of a home-based, physiotherapy supervised, PRT program to improve isometric and functional muscle strength in children with SCP without negative effects on muscle properties or any serious adverse events. Clinical Trial Registration: ClinicalTrials.gov, identifier NCT03863197.

Comparison of the Strength and Electromyography of the Evertor Muscles With and Without Toe Flexion in Patients With Chronic Ankle Instability.

BACKGROUND: Weakness of evertor strength is controversial in chronic ankle instability (CAI). Ankle evertor muscles are attached to the toe joints as well as to the metatarsal bone. Therefore, it is necessary to consider toe joint position for the measurement of evertor strength. The purpose of this study was to compare ankle evertor strength and muscle activity during eversion with and without toe flexion (TF) in individuals with CAI and individuals in a healthy group. METHODS: Fifteen subjects with CAI and 15 healthy subjects participated in this study. Isometric ankle evertor strength and muscle activity of the peroneus longus (PL), peroneus brevis (PB), and extensor digitorum longus (EDL) were measured during eversion with and without TF. RESULTS: The results indicated a significant interaction effect in evertor strength (P = .03) and no significant interaction effect on EMG of the PL (P = .08), PB (P = .12), and EDL (P = .28). However, measurements of muscle activity of the PL and PB between eversion with and without TF revealed a significant difference in the CAI group (P < .01) and no significant difference in the healthy group (PL: P = .07; PB: P = .13). CONCLUSION: The results indicated that subjects with CAI had increased EDL compensation and reduced selective activation of the PL and PB during eversion. CLINICAL RELEVANCE: Our findings suggest that clinicians should consider the activation of EDL when training the evertor of patients with CAI.

Muscle Strength and Flexibility in Male Marathon Runners: The Role of Age, Running Speed and Anthropometry.

Most studies on marathon runners have focused on physiological parameters determining performance, whereas neuromuscular aspects, such as muscle strength and flexibility, have received less attention. Thus, the aim of the present study was to examine the relationship of age, body composition, and running speed with muscle strength and flexibility of recreational marathon runners. Male marathon runners (n = 130, age 44.1 ± 8.6 years, height 176 ± 6 cm, body mass 77 ± 9 body mass index 24.7 ± 2.6 kg.m-2, and race speed 10.29 ± 1.87 km/h) were separated into eight age groups (<30, 30-35, 55-60, >60 years). Four weeks before competing in a marathon, participants performed the sit-and-reach test (SAR), squat jumps (SJ), and countermovement jumps (CMJ), and four isometric muscle strength tests (right and left handgrip, lifting with knees extended and flexed), providing an index of overall isometric muscle strength in absolute (kg) relative to body mass values (kg.kg-1 body mass). Afterward, participants competed and finished the Athens Classic Marathon (2017), and race speed was used as an index of running performance. As an average for the whole sample, SAR was 17.6 ± 8.5 cm, SJ was 24.3 ± 4.2 cm, CMJ was 25.8 ± 4.8 cm, overall isometric muscle strength was 386 ± 59 kg in absolute values and 5.06 ± 0.78 kg/kg of body mass in relative terms. The older age groups had the lowest scores in SJ (p < 0.001, ηp 2 = 0.298) and CMJ (p < 0.001, ηp 2 = 0.304), whereas no age-related difference in SAR (p = 0.908, ηp 2 = 0.022), absolute (p = 0.622, ηp 2 = 0.042) and relative isometric muscle strength (p = 0.435, ηp 2 = 0.055) was shown. Race speed correlated moderately with relative isometric strength (r = 0.42, p < 0.001), but not with the other neuromuscular measures (r < 0.13,p > 0.130). In summary, age-related differences were shown in jumping ability, but not in flexibility and isometric muscle strength. Although these parameters - except relative strength - did not relate to running speed, they were components of health-related physical fitness. Consequently, coaches and runners should consider exercises that include stretching and strengthening in their weekly program to ensure adequate levels for all components of health-related physical fitness.

Relative Age Effect on Youth Female Volleyball Players: A Pilot Study on Its Prevalence and Relationship With Anthropometric and Physiological Characteristics.

The relative age effect (RAE) on human performance has been well studied in many sports, especially in soccer; however, little information has been available about the prevalence of RAE in volleyball, and its role on anthropometric and physiological characteristics. The aim of the present study was to examine (a) the prevalence of RAE in selected (i.e., to be considered for the national team) and non-selected youth female volleyball players, and (b) the relationship of birth quarter (BQ) with anthropometric and physiological characteristics. Selected (n = 72, age 13.3 ± 0.7 years, weight 62.0 ± 7.2 kg, height 1.72 ± 0.06 m) and non-selected female volleyball players (n = 53, age 13.9 ± 1.1 years, weight 56.4 ± 7.3 kg, height 1.66 ± 0.06 m) performed a series of anthropometric and physiological tests. Twenty-six selected participants were born in the first quarter of the year, 19 in the second, 14 in the third, and 13 in the forth. The corresponding frequency by BQ in non-selected participants was 12, 12, 17, and 12. No association was observed between the number of participants and their frequency by BQ neither in the selected (χ 2 = 2.79, p = 0.425) nor in the non-selected group (χ 2 = 0.64, p = 0.886). Anthropometric and physiological characteristics did not vary by BQ (p > 0.05). The absence of RAE in female volleyball players and the similarities of anthropometric and physiological characteristics among BQ might be due to technical-tactical character of this sport. These findings would be of great practical value for coaches and fitness trainers working with young volleyball players.

Is muscle strength in a painful limb affected by knee pain status of the contralateral limb? - Data from the Osteoarthritis Initiative.

Contralateral knee pain has been suggested to be associated with muscle weakness in a pain-free knee, potentially through a mechanism of central nervous inhibition. Whether contralateral knee pain also affects muscle strength in a painful knee, however, is unknown. Here we study the extent to which isometric muscle strength differs between matched painful limbs of people with unilateral knee pain vs. matched painful limbs people with bilateral knee pain. To that end, 163 participants with unilateral knee pain were identified from the Osteoarthritis Initiative. Unilaterally painful (UP) limbs were defined as having numerical rating scale (NRS) ≥4/10, infrequent/frequent pain in the painful limb, while contralateral pain-free limbs were defined by NRS=0-1, no/infrequent pain and Western Ontario and McMaster Universities Arthritis Index (WOMAC) ≤1. The comparator group were matched bilaterally painful (BP) limbs. Maximum isometric muscle strength (N) was compared between 1:1 matched BP and UP limbs. Extensor strength was found to be lower in BP limbs than in UP limbs, (-2.9%; p=0.39) but this difference was not statistically significant. Extensor strength was significantly lower in the UP vs. contralateral pain-free limbs (-6.2%; p<0.001). No differences were observed between BP and contralateral painful limbs (0.6%; p=0.87). In conclusion, the current results identify a slight reduction of maximum knee extensor strength in a painful limb, when the contralateral knee is also painful. In contrast to pain-free limbs, this effect did not reach statistical significance, but the overall findings support the concept of central nervous inhibition of muscle strength by contralateral knee pain.

Effects of Prednisone on a Patient with Dysferlinopathy Assessed by Maximal Voluntary Isometric Contraction: Alternate-Day Low-Dose Administration for a 17-Year Period.

Glucocorticoids are candidates for the pharmacological treatment of dysferlinopathy. Deflazacort, however, showed a worse effect on muscle strength than placebo. Alternate-day low-dose prednisone may have beneficial effects with fewer adverse effects. The outcomes for a female patient with dysferlinopathy (limb-girdle muscular dystrophy type 2B) were assessed by maximal voluntary isometric contraction (MVIC) using a newly devised chair and arm table with push-pull type strain gauges. Grip strength was also measured isometrically. Prednisone 15 mg was started orally at the age of 24 years and was taken every other day in the morning until 41 years of age. The MVIC of flexion of the knees and elbows increased gradually and significantly. The MVIC of extension of the knees and elbows increased to a lesser extent. Isometric grip strength showed no remarkable increase, but strength was sustained over 10 years. Muscle fiber types account for these differences. The beneficial effects of alternate-day prednisone treatment on dysferlinopathy are reported.