Kinematic characteristics of elbow joint range of motion in elite Chinese freestyle swimmers with elbow pain during dry-land simulations of swimming strokes.

The aim of this study was to obtain quantitative data on elbow joint ROM in elite freestyle swimmers with EP in China. Of the 50 elite freestyle swimmers recruited, 41 completed all measurements during dry-land swimming stroke simulations. Elbow joint angle, velocity, and acceleration were measured using inertial measurement units. The RMSE/D was calculated to determine the elbow joint ROM deviation. Joint angle (3.33 ∘-42.96 ∘), angular velocity (-364.15 to 245.69 ∘/s), and angular acceleration (-7051.80 to 1465.35 ∘/s2) were significantly different between the critical pain and healthy. The probability distributions of joint angle (15.47 ∘ ±14.54 ∘), angular velocity (2.41 ∘ ±111.06 ∘/s), and angular acceleration (1.93 ± 2222.6 ∘/s2) in the slight pain group were significantly different betweenhealthy and critical pain. The RMSE/D distributions of angular velocity (28.3%) and acceleration (21.48%) in the critical pain deviated from the healthy. The peak value-RMSE/D matrix model obtained proved that elbow ROM significantly differed between the elite freestyle swimmers with EP and the healthy. Angular velocity and acceleration indicate the weakness and negative influence of kinematics on patients with EP. Thus, Potential solutions are to constantly optimise freestyle swimming techniques and strengthen the arm muscles.

Knee Laxities Changes with Sex-steroids throughout the Menstrual Cycle Phases in Athlete and Non-athlete Females.

Objective: Our study investigated changes of knee laxities in athletes and non-athletes females and relationship between knee laxity and sex-steroid at menstrual cycle phases. Methods: Forty six healthy females, twenty four athletes and twenty two non-athletes not on hormone contraceptive pills, had no previous knee injuries and with regular menstrual cycles for 3 consecutive months, participated in the study. Medial and lateral knee laxities were determined by varus-valgus tests at follicular, ovulatory and luteal phases. Serum level of relaxin, estrogen, progesterone and testosterone were determined by ELISA and radioimmunoassay. Results: Knee laxities in athletes and non-athletes at 0° and 20° flexion were the highest in luteal phase with non-athletes possess greater laxity than athletes. Positive correlation between progesterone and relaxin levels with knee laxities were observed. Meanwhile, the levels of both hormones were highest in the luteal phase. Conclusion: Increased medial and lateral knee laxities in athletes and non-athletes associated with high serum progesterone and relaxin levels in luteal phase may contribute toward increased risk of non-contact knee injury. However, lower knee laxity in athletes than non-athletes suggest that exercise could be a protective factor.

Effects of isometric training and R.I.C.E. treatment on the arm muscle performance of swimmers with elbow pain.

The effects of IT and R.I.C.E. treatment on arm muscle performance in overhead athletes with elbow pain (EP) have been partially validated. However, there is a lack of research evidence regarding the efficacy of these two methods on arm muscle performance among swimmers with EP. The aim of this study was to investigate the trends and differences in the effects of IT and R.I.C.E. treatment on arm muscle performance among swimmers with EP. The main outcomes were the time effects and group effects of interventions on muscle voluntary contraction (MVC). Sixty elite freestyle swimmers from Tianjin, China, voluntarily participated in the study and completed a 10-week intervention program. Swimmers with EP in the IT group showed a positive trend in MVC, with an approximately 2% increase, whereas the MVC of subjects in the R.I.C.E. treatment group and control group decreased by approximately 4% and 5%, respectively. In comparison, the effects of the IT intervention on the MVC of the triceps and brachioradialis muscles in swimmers with EP were significant (p = 0.042 < 0.05, p = 0.027 < 0.05). The mean MVC value of the IT group (0.60) was greater than that of the other two groups (0.51, 0.50). IT has a beneficial impact on the MVC performance of the triceps and brachioradialis muscles in swimmers with EP. It is recommended that professionals consider incorporating IT into regular training routines to mitigate the risk of EP issues. Future research should examine the effectiveness of both interventions on hand-grip strength and completion time in 50-m freestyle swim drills in order for swimmers with EP to return to this sport.

Central effects of mouth rinses on endurance and strength performance.

Rinsing the mouth with a carbohydrate (CHO) solution has been shown to enhance exercise performance while reducing neuromuscular fatigue. This effect is thought to be mediated through the stimulation of oral receptors, which activate brain areas associated with reward, motivation, and motor control. Consequently, corticomotor responsiveness is increased, leading to sustained levels of neuromuscular activity prior to fatigue. In the context of endurance performance, the evidence regarding the central involvement of mouth rinse (MR) in performance improvement is not conclusive. Peripheral mechanisms should not be disregarded, particularly considering factors such as low exercise volume, the participant's fasting state, and the frequency of rinsing. These factors may influence central activations. On the other hand, for strength-related activities, changes in motor evoked potential (MEP) and electromyography (EMG) have been observed, indicating increased corticospinal responsiveness and neuromuscular drive during isometric and isokinetic contractions in both fresh and fatigued muscles. However, it is important to note that in many studies, MEP data were not normalised, making it difficult to exclude peripheral contributions. Voluntary activation (VA), another central measure, often exhibits a lack of changes, mainly due to its high variability, particularly in fatigued muscles. Based on the evidence, MR can attenuate neuromuscular fatigue and improve endurance and strength performance via similar underlying mechanisms. However, the evidence supporting central contribution is weak due to the lack of neurophysiological measures, inaccurate data treatment (normalisation), limited generalisation between exercise modes, methodological biases (ignoring peripheral contribution), and high measurement variability.Trial registration: PROSPERO ID: CRD42021261714.

Knee Laxities Changes with Sex-steroids throughout the Menstrual Cycle Phases in Athlete and Non-athlete Females / Mudanças na flacidez do joelho com esteroides sexuais durante as fases do ciclo menstrual em mulheres atletas e não atletas

Abstract Objective: Our study investigated changes of knee laxities in athletes and non-athletes females and relationship between knee laxity and sex-steroid at menstrual cycle phases. Methods: Forty six healthy females, twenty four athletes and twenty two non-athletes not on hormone contraceptive pills, had no previous knee injuries and with regular menstrual cycles for 3 consecutive months, participated in the study. Medial and lateral knee laxities were determined by varus-valgus tests at follicular, ovulatory and luteal phases. Serum level of relaxin, estrogen, progesterone and testosterone were determined by ELISA and radioimmunoassay. Results: Knee laxities in athletes and non-athletes at 0° and 20° flexion were the highest in luteal phase with non-athletes possess greater laxity than athletes. Positive correlation between progesterone and relaxin levels with knee laxities were observed. Meanwhile, the levels of both hormones were highest in the luteal phase. Conclusion: Increased medial and lateral knee laxities in athletes and non-athletes associated with high serum progesterone and relaxin levels in luteal phase may contribute toward increased risk of non-contact knee injury. However, lower knee laxity in athletes than non-athletes suggest that exercise could be a protective factor.

Resumo Objetivo: Nosso estudo investigou alterações na lassidão do joelho em atletas e não atletas do sexo feminino e a relação entre a lassidão do joelho e esteroides sexuais nas fases do ciclo menstrual. Métodos: Quarenta e seis mulheres saudáveis, vinte e quatro atletas e vinte e duas não atletas, sem uso de pílulas anticoncepcionais hormonais, sem lesões anteriores no joelho e com ciclos menstruais regulares por 3 meses consecutivos, participaram do estudo. A lassidão medial e lateral do joelho foi determinada por testes de varo-valgo nas fases folicular, ovulatória e lútea. Os níveis séricos de relaxina, estrógeno, progesterona e testosterona foram determinados por ensaio imunoenzi mático (ELISA) e radioimunoensaio. Resultados: A lassidão do joelho em atletas e não atletas em 0° e 20° de flexão foi maior na fase lútea; as não atletas apresentavam maior lassidão do que as atletas. Houve uma correlação positiva entre os níveis de progesterona e relaxina e a lassidão do joelho. Além disso, os níveis desses dois hormônios foram maiores na fase lútea. Conclusão: O aumento da lassidão medial e lateral do joelho em atletas e não atletas, associado a altos níveis séricos de progesterona e relaxina na fase lútea, pode contribuir para o aumento do risco de lesão sem contato no joelho. No entanto, a menor lassidão do joelho em atletas do que em não atletas sugere que o exercício pode ser um fator protetor.

Distribution and Prevalence of Elbow Pain (EP) in Elite Swimmers in Tianjin, China-A Regional Epidemiological Study.

Elbow pain (EP) in overhead sports is a common phenomenon. Swimming is classified as an overhead sport, but a lack of attention regarding EP in swimming has created a gap in the knowledge around elite freestyle swimming in Tianjin, China. The purpose of this study was to identify the distribution and prevalence of EP among elite freestyle swimmers in Tianjin, China. The methodology involved a total of 311 qualified participants who volunteered to undertake all measurements. The main findings showed that 183 of the elite freestyle swimmers in this study had EP (accounting for 58.84% of the total 311 participants), with 147 in slight pain and 36 in critical pain. The characteristics of a heavier body weight, taller height, longer left/right forearm length, and longer weekly average training hours serve as contributing factors to the occurrence of EP issues. Gender, age, weekly average training hours, and left/right forearm length are the primary factors correlating with and influencing the assessment scores. In conclusion, swimmers with longer weekly training hours, older ages, heavier bodyweight, and longer forearm lengths should receive greater attention in relation to EP. Regular assessments at a high frequency serve as a means to identify the risk of EP.

Effects of Self-management Program as Adjunctive to Usual Rehabilitation Exercise on Pain and Functional Outcomes in Knee Osteoarthritis: A Randomized Controlled Trial.

BACKGROUND: Home-based exercise (HBE) and patient education (EDU) have been reported as beneficial additions to usual knee osteoarthritis (KOA) rehabilitation. However, previous trials mostly examined the effects of HBE and EDU separately. Thus, this study aimed to evaluate the effects of a structured combined HBE and EDU program in addition to usual KOA rehabilitation on pain score, functional mobility, and disability level. STUDY DESIGN: A parallel-group, single-blinded randomized controlled trial. METHODS: Eighty adults with KOA were randomly allocated to experimental (n=40) and control (n=40) groups. All participants underwent their usual physiotherapy care weekly for eight weeks. The experimental group received a structured HBE+EDU program to their usual care, while the control group performed home stretching exercises to equate treatment time. The Knee Injury and Osteoarthritis Outcome Score (KOOS) for the disability level, visual analogue scale (VAS) for pain, and timed up-and-go test (TUG) for mobility were measured pre-post intervention. RESULTS: After eight weeks, the experimental group demonstrated significant improvements in the KOOS (all subscales), pain VAS, and TUG scores compared to baseline (P<0.001); meanwhile, only KOOS (activities of daily living and sports subscales) was significant in the control group. Relative to the control, the experimental group presented higher improvements (P<0.001) by 22.2%, 44.1%, and 15.7% for KOOS, pain VAS, and TUG, respectively. CONCLUSION: Integrating the HBE+EDU program into usual KOA rehabilitation could reduce pain and disability, while it improved functional mobility. The finding of this study suggests a combination of a structured HBE and EDU program to be considered as part of mainstream KOA management.

Comparison between Low-Level and High-Intensity Laser Therapy as an Adjunctive Treatment for Knee Osteoarthritis: A Randomized, Double-Blind Clinical Trial.

BACKGROUND: Low-level (LLLT) and high-intensity laser therapy (HILT) can be beneficial additions to knee osteoarthritis (KOA) rehabilitation exercises; however, it is still being determined which electrophysical agent is more effective. AIM: To compare the effects of LLLT and HILT as adjuncts to rehabilitation exercises (LL + EX and HL + EX) on clinical outcomes in KOA. METHODS: Thirty-four adults with mild-to-moderate KOA were randomly allocated to either LL + EX or HL + EX (n = 17 each). Both groups underwent their respective intervention weekly for twelve weeks: LL + EX (400 mW, 830 nm, 10 to 12 J/cm2, and 400 J per session) or HL + EX (5 W, 1064 nm, 19 to 150 J/cm2, and 3190 J per session). The laser probe was placed vertically in contact with the knee and moved in a slow-scan manner on the antero-medial/lateral sides of the knee joint. Participants' Knee Injury and Osteoarthritis Outcome Score (KOOS), Numerical Pain Rating Scale (NPRS), active knee flexion, and Timed Up-and-Go test (TUG) were assessed. RESULTS: Post intervention, both groups showed improvements in their KOOS, NPRS, active knee flexion, and TUG scores compared to baseline (p < 0.01). The mean difference of change in KOOS, NPRS, and active knee flexion scores for the HL + EX group surpassed the minimal clinically important difference threshold. In contrast, the LL + EX group only demonstrated clinical significance for the NPRS scores. CONCLUSIONS: Incorporating HILT as an adjunct to usual KOA rehabilitation led to significantly higher improvements in pain, physical function, and knee-related disability compared to LLLT applied in scanning mode.

Effect of Exercise on Arterial Stiffness in Healthy Young, Middle-Aged and Older Women: A Systematic Review.

Arterial stiffness, an age-dependent phenomenon, is improved with exercise, which in turn may prevent cardiovascular diseases in women. However, there is a lack of consolidated information on the impact of exercise on arterial stiffness among healthy women. The aim of this review was to (i) analyse the effect of exercise on arterial stiffness in healthy young, middle-aged, and older women, and (ii) recommend types, intensity, and frequency for each age group. Database searches on PubMed, ScienceDirect, Web of Science, and Scopus were conducted using PRISMA guidelines until September 2022. The keywords were: exercise, women/female, and arterial stiffness. The inclusion criteria were: healthy women, supervised exercise, and arterial stiffness measures. Study quality and bias were assessed using the PEDro scale. Fifty-one papers were classified into young (n = 15), middle-aged (n = 14), and older (n = 22) women. Improvements in arterial stiffness were observed among: young women (Pulse Wave Velocity, PWV: 4.9-6.6 m/s), following an 8-week high-intensity aerobic (3 days/week) or hypoxic high-intensity interval training; middle-aged women (PWV: 5.1-7.9 m/s), aerobic exercise with moderate intensity or stretching exercise at "moderate to heavy" (Borg Scale), 20-30 s per site, 10 s of rest interval for 30 min; and for older women (PWV: 7.9-15.6 m/s), resistance training at light intensity, aerobic exercise at any intensity, or a combination of the two exercises. This review shows that arterial stiffness increases with age in healthy women and has an inverse relationship with exercise intensity. Therefore, when prescribing exercise to improve arterial stiffness, age and arterial stiffness measures should be accounted for.

Analysis of Research Trends on Elbow Pain in Overhead Sports: A Bibliometric Study Based on Web of Science Database and VOSviewer.

The publications on elbow pain (EP) in overhead sports are increasing. The results of previous studies mostly focus on the influence of EP in the ball game and throwing sports. Thus, a bibliometric analysis of these publications may show the direction of hot topics and future research trends. The purpose of this study is to identify the research trends on EP in overhead sports. For the methods, the first step is to use the main keywords of 'Elbow pain' and 'Overhead sport' merging auxiliary vocabulary to reach the relevant global publications between 1970 and 2022 in the Web of Science (WoS) database. The literature data set is imported into EndNote literature manager software to remove duplication. Secondly, the duplication-reduced articles are imported to an Excel sheet according to the inclusion and exclusion criteria of this study. In the third step, VOSviewer software is applied as the main analysis tool in extracting data for analysis from the articles. Then, the main research results for three aspects are obtained by VOSviewer software which extracted and analyzed the parameters of author name, article title, publication journal, keywords, organization, publication country/region, and the sum of times cited from 455 qualified papers. The study found that the United States of America made the most outstanding contribution to this theme study. The research on EP in overhead sports in China requires more attention from scholars. EP in swimming is a new research direction worthy of attention. In conclusion, the research results prove the growth trend of EP in overhead sports. The EP problem not only exists in the ball game and throwing sports but also swimming. Sport commercialization and the involvement of related professional sports organizations determine the degree of EP's attention in a specific sport and the development of solutions. The development of a region or country also affects the depth and scope of EP study. Clinical research development and in-depth exploration are one of the bases to solve EP problems. Non-clinical action is beneficial to EP patients, but it still needs to be explored and studied.

Interaction of hand orientations during familiarization of a goal-directed aiming task.

The purpose of the present study was to examine errors for an isometric goal-directed aiming task during familiarization at different hand orientation. Interaction between neutral and pronated hand orientations with and without directional feedback would provide insights into short-term adaptations and the nature of control. In this study, 30 healthy right-handed adults (age, 22.7 ± 3.1 years; weight, 69.4 ± 16.6 kg; height, 166.7 ± 7.9 cm) were randomly assigned to neutral or pronated hand orientation conditions. To assess familiarization, participants performed ten sets (16 targets/set) of goal-directed aiming task with continuous visual feedback towards targets symmetrically distributed about the origin. Following familiarization, participants then completed eight sets; four sets with and four sets without directional feedback, in an alternated order. For both hand orientations, directional errors were reduced in the first two sets (p < 0.05), suggesting only three sets were required for familiarization. Additionally, the learning rate was also similar for both hand orientations. Following familiarization, aiming errors without feedback were significantly higher than with feedback while no change between sets was observed, regardless of hand orientation. Aiming errors were reduced in the early phase with and without visual feedback, however, in the late phase, errors were corrected when visual feedback was provided. It suggests that hand orientation does not affect familiarization, and mechanisms similar to rapid learning may be involved. It is probable that learning is consolidated during familiarization along with feedforward input to maintain performance. In addition, proprioceptive feedback plays a role in reducing errors early, while the online visual feedback plays a role in reducing errors later, independent of hand orientation.

Starving Your Performance? Reduced Preexercise Hunger Increases Resistance Exercise Performance.

BACKGROUND: Preexercise food intake enhances exercise performance due, in part, to the provision of exogenous carbohydrate. Food intake also suppresses hunger, but the specific influence of hunger on exercise performance has not been investigated. This study aimed to manipulate hunger by altering preexercise meal viscosity to examine whether hunger influences performance. METHODS: Sixteen resistance-trained males completed 2 experimental trials ingesting either high viscosity semisolid (SEM) and low viscosity liquid (LIQ) carbohydrate-containing meals 2 hours before performing 4 sets of back squat (85 [22] kg) and bench press (68 [13] kg) to failure at 90% 10-repetition maximum. Subjective hunger/fullness as well as plasma concentrations of glucose, insulin, ghrelin, and peptide tyrosine-tyrosine were measured before and periodically after the meal. Repetitions completed in sets were used to determine exercise performance. RESULTS: Hunger was lower, and fullness was greater during SEM compared with LIQ immediately before and during exercise (P < .05). Total repetitions completed for back squat were approximately 10% greater in SEM (SEM 57 [9]; LIQ 51 [7] repetitions; P = .001) with no difference in bench press repetitions (SEM 48 [11]; LIQ 48 [10] repetitions; P = .621). Postprandial glucose concentrations were greater during LIQ (12% increase in peak glucose) but were similar throughout exercise. CONCLUSION: This study demonstrates that exercise performance in back squat was increased in the SEM trial concomitant to a reduction in hunger. Therefore, this study provides novel data that suggest that exercise performance might be influenced by hunger, at least for resistance exercise.

Effects of low-level and high-intensity laser therapy as adjunctive to rehabilitation exercise on pain, stiffness and function in knee osteoarthritis: a systematic review and meta-analysis.

BACKGROUND: When treating knee osteoarthritis (KOA), rehabilitation exercise is often combined with low-level (LLLT) or high-intensity laser therapy (HILT). However, the effectiveness of these combinations is still uncertain. OBJECTIVE: To examine the effects of LLLT or HILT combined with rehabilitation exercise (LLLT+E or HILT+E) on pain, stiffness and function in KOA. DATA SOURCES: Five databases (PubMed, Web of Science, CINAHL, PEDro and SPORTDiscus) were searched for relevant studies published up to 31 December 2019. STUDY SELECTION: KOA randomised controlled trials, LLLT+E or HILT+E against exercise alone with or without placebo laser, reported clinical outcomes, human studies and English language. DATA SYNTHESIS: Methodological quality was assessed by the PEDro and Cochrane risk-of-bias scales, and the meta-analysis was undertaken using RevMan 5.3. RESULTS: Of the 10 retrieved studies, six investigated LLLT+E, three on HILT+E, and one evaluated both. All the studies had high PEDro scores. However, as most of the studies employed a single type of laser therapy, only indirect comparison of LLLT+E and HILT+E was possible. This study found all treatment modalities were effective in reducing KOA symptoms. Interestingly, relative to control, the meta-analysis showed significant improvements in knee pain, stiffness and function for the HILT+E. CONCLUSION: Both LLLT and HILT are beneficial as adjuncts to rehabilitation exercise in the management of KOA. Based on an indirect comparison, the HILT+E seems to have higher efficacy in reducing knee pain and stiffness, and in increasing function. To confirm this finding, a direct comparative investigation of the two types of laser therapy may be necessary. Systematic review registration PROSPERO ID CRD42020206228.

The effect of 10 days of energy-deficit diet and high-intensity exercise training on the plasma high-density-lipoprotein (HDL) level among healthy collegiate males.

ABSTRACTAn energy-deficit (ED) diet increases lipid mobilisation, while endurance exercise improves lipid profile by promoting formation of high-density lipoproteins (HDLs) among moderately active population. However, it is not clear whether ED with high-intensity exercise training can improve lipid profiles. Therefore, 20 recreationally active males (20.3 ± 2.7 years old with peak oxygen consumption (V˙O2peak) of 2.8 ± 0.2 L min-1) with HDL concentration of 1.44 ± 0.32 mmol L-1, were evenly allocated to either an ED group (1590 ± 79 kcal day-1: 40% of total caloric omitted at lunchtime) or a control (CON) group (2570 ± 139 kcal day-1). Participants in both groups performed high-intensity cycling at 90% V˙O2peak at a constant workload for 8 min, 2 h after breakfast on day D0, D2, D4, D6, D8 and D10 (Dn is day number), after which blood samples were collected. In ED, compared to D0, triglycerides (TG) decreased on D6-10 (p < .01) while total low-density lipoprotein (LDL), total cholesterol (TC) increased on D2-10, while HDL progressively increased on D6-10 (p = .01) with a final value of 1.67 ± 0.24 mmol L-1. In CON, there were no changes in TG, TC and HDL while LDL was reduced on D8-10 (p = .01). Moreover, the proportions of TC/HDL and LDL/HDL increased in ED on D2-10 and D2-8 (p = .05), respectively, while LDL/HDL in CON was reduced on D8-10 (p = .01). In brief, 10 days of ED and a series of high-intensity exercise sessions show progressive elevation of HDL which suggest longer period is required to observe changes in lipid ratios.

Prevalence, patterns and factors associated with injury: comparison between elite Malaysian able-bodied and para-badminton players.

OBJECTIVES: This study aimed to determine and compare the prevalence, patterns and factors associated with injury between elite Malaysian able-bodied and para-badminton players. METHODS: Medical records from July 2007 to December 2017 were reviewed. RESULTS: Among 209 able-bodied players, 1010 injuries were reported. The injuries affected the lower limb (67.2%), sustained during training (94.2%), overuse in nature (38.7%), and involving mostly junior players (62.4%). The injury rate was 94/year, lower than previously reported. Patellar tendinopathy and muscle strain to the upper limb and torso were the commonest. Age, sex and history of injury were predictors of injury. Lower limb injury was a predictor of upper limb and torso injuries, while history of injury to the upper limb and/or torso was a predictor of lower limb injury. Meanwhile, among 18 para-badminton players, 62 injuries were reported from July 2014 to December 2017, which involved the lower limb (45.2%), sustained during training (87.1%), overuse in nature (54.8%), and involved mostly standing-class players (77.8%). The injury rate was 10/year. Patellar tendinopathy, rotator cuff tendinopathy and back muscle strain were the commonest. The patterns of injury (site, occasion and nature) were similar between groups, except for the shoulder where nature was overuse in para-badminton players compared to acute in able-bodied players. CONCLUSIONS: All players are susceptible to training-related injuries, particularly to the lower limb. Over the last decade, an increase in the injury index for the lower limb and a shift from chronic to acute for the upper limb were observed among able-bodied players. Age, sex and history of injury expose able-bodied players to greater risk. Meanwhile, for para-badminton players, overuse shoulder and knee injuries are commonest. These findings necessitate a comprehensive injury prevention program that encompasses all body regions with an emphasis on the lower limb among elite Malaysian able-bodied and para-badminton players.

Contralateral Effects of Eccentric Exercise and DOMS of the Plantar Flexors: Evidence of Central Involvement.

Purpose: Peripheral and central factors play important roles in the reduction of motor performance following damaging eccentric exercise and delayed onset muscle soreness (DOMS). Following this regime, contralateral limbs could also be affected; however, the factors involved remain inconclusive. The purpose of this study was to distinguish the peripheral and central factors following eccentric contraction and DOMS of the plantar flexors in treated and contralateral homologous limbs. Methods: Ten males (BMI = 25.08 ± 1.69kgm-2; age = 28.70 ± 4.24 years) were randomly assigned to experimental (DOM) or control (CON) groups. The DOM group performed a damaging eccentric exercise, while the CON group rested. Plasma creatine kinase (CK), pain rating scale (PRS), muscle stiffness, maximal voluntary contraction (MVC), and neural voluntary activation (VA) were measured before, after 10 min, and after 24, 48, and 72 hr on treated and contralateral limbs. Results: Following exercise, CK increased until after 48 hr, while PRS increased until after 72 hr compared to the CON group. Importantly, MVC was reduced at all time points, with the greatest reduction observed after 24 hr (-16%), while VA was affected until after 48 hr, with the greatest reduction at after 10 min (-7%). Interestingly, a "cross-over effect" was observed in contralateral limbs when PRS, MVC, and VA were negatively affected following the same pattern (time line) as treated limbs (-13% peak MVC reduction; -3.5% peak VA reduction). Conclusion: These findings suggest a substantial central contribution to the reduction in force immediately following eccentric exercise and to a lesser extent during the latter part of DOMS in both treated and contralateral limbs.

Relationship between objective and subjective hydration measures on sprint performance among soccer players during actual matches in hot and humid environment.

BACKGROUND: Studies that investigate the effect of hydration on soccer performance in the heat are mostly carried out in a laboratory-controlled environment or simulated setting. Generally, on site, hydration is measured subjectively. Hence, the relationships between objective and subjective hydration measures during actual soccer matches in natural hot and humid environment with performance remain unclear. METHODS: Forty-two soccer players (age: 27.34±3.62 years; BMI: 23.80±2.70 kg/m2; temperature: 30.8±1.92 °C; humidity: 82±1.4%) hydration status were assessed using urine specific gravity (USG) and bodyweight (BW) as the objective measures, meanwhile, thirst was measured subjectively using a thirst scale. For performance evaluation, 20 and 50 m sprint time were measured before and after match. RESULTS: The results showed a significant relationship between USG and sprint time (r=1.00, CI 0.98-0.99; P<0.05), and as expected, USG at post-match was significantly higher than pre-match (P<0.05) indicating dehydration. In line, changes (between post and pre-match) in BW also showed positive relationship with changes in sprint time (r=0.99, CI 0.98-0.99; P<0.05). Not to our expectation, the self-reported thirst level was not found to be correlated with USG and sprint time. CONCLUSIONS: Objective measures better reflect hydration status and predict sprint performance compared to subjective measure when playing in hot and humid environment. Players need to monitor their hydration status to maintain their sprint performances.

The effect of Eurycoma Longifolia on the regulation of reproductive hormones in young males.

Eurycoma longifolia supplementation increases testosterone levels in humans via activation of the hypothalamic-pituitary-gonadal axis and/or the hypothalamic-pituitary-adrenal axis mainly in older adults and nonhealthy populations. This study aimed to assess the impact of Eurycoma longifolia on the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal axes in healthy young males since this might promote functional testosterone prowess. Thirty-two males (24.4 ± 4.7 years; 1.74 ± 0.07 m; 73.7 ± 8.4 kg) in a placebo-controlled, double-blind, matched-paired study received 600 mg/day Eurycoma longifolia or placebo for two weeks. Blood analysis using repeated measures analysis of variance showed significant interaction and time effects for testosterone (F1,30  = 9.04, p = .005), free testosterone (F1,30  = 7.13, p = .012) and estradiol (F1,30  = 8.07, p = .008) levels in favour of the treatment group, while luteinising hormone, follicle-stimulating hormone and sexual hormone-binding globulin did not. The lack of changes in luteinising hormone and follicle-stimulating hormone levels suggests that a lesser role played by Eurycoma longifolia in activating the hypothalamic-pituitary-gonadal axis in the young adults. The raised testosterone level may be due to a greater rate of hormone production via the hypothalamic-pituitary-adrenal axis. The supplementation of Eurycoma longifolia for two weeks demonstrates steroidogenic effects on young men were dose-related. Consequently, the raised testosterone following Eurycoma longifolia supplementations could benefit muscle and strength gain in young adults.

Effects of 8 Weeks of Balance Training, Virtual Reality Training, and Combined Exercise on Lower Limb Muscle Strength, Balance, and Functional Mobility Among Older Men: A Randomized Controlled Trial.

BACKGROUND: Poor muscle strength, balance, and functional mobility have predicted falls in older adults. Fall prevention guidelines recommend highly challenging balance training modes to decrease falls; however, it is unclear whether certain modes are more effective. The purpose of this study was to determine whether traditional balance training (BT), virtual reality balance training (VR), or combined exercise (MIX) relative to a waitlist control group (CON) would provoke greater improvements in strength, balance, and functional mobility as falls risk factor proxies for falls in older men. HYPOTHESIS: We hypothesized that 8 weeks of MIX will provoke the greatest improvements in falls risk factors, followed by similar improvements after BT and VR, relative to the CON. STUDY DESIGN: Single-blinded randomized controlled trial NCT02778841 (ClinicalTrials.gov identifier). LEVEL OF EVIDENCE: Level 2. METHODS: In total, 64 community-dwelling older men (age 71.8 ± 6.09 years) were randomly assigned into BT, VR, MIX, and CON groups and tested at baseline and at the 8-week follow-up. The training groups exercised for 40 minutes, 3 times per week, for 8 weeks. Isokinetic quadriceps and hamstrings strength on the dominant and nondominant legs were primary outcomes measured by the Biodex Isokinetic Dynamometer. Secondary outcomes included 1-legged stance on firm and foam surfaces, tandem stance, the timed-up-and-go, and gait speed. Separate one-way analyses of covariance between groups were conducted for each outcome using baseline scores as covariates. RESULTS: (1) MIX elicited greater improvements in strength, balance, and functional mobility relative to BT, VR, and CON; (2) VR exhibited better balance and functional mobility relative to BT and CON; and (3) BT demonstrated better balance and functional mobility relative to CON. CONCLUSION: The moderate to large effect sizes in strength and large effect sizes for balance and functional mobility underline that MIX is an effective method to improve falls risk among older adults. CLINICAL RELEVANCE: This study forms the basis for a larger trial powered for falls.

Evaluation of Shoulder and Knee Isokinetic Strength Profile Among Elite Adolescent Badminton Players.

CONTEXT: Badminton continues to be a highly competitive sport where training is introduced at an early age and load has intensified. This exposes players to a greater risk of injuries, in particular when assessing related training outcomes such as strength, agonist-antagonist ratio, and bilateral deficit among adolescents where age- and sex-associated growth and development should be considered. OBJECTIVE: To evaluate strength profile of the upper and lower limbs among adolescent elite Malaysian badminton players. DESIGN: Cross-sectional study. SETTING: Laboratory. PARTICIPANTS: Forty-eight asymptomatic athletes (24 males and 24 females) were grouped into early and late adolescence (13-14 y old and 15-17 y old, respectively). MAIN OUTCOME MEASURE(S): Strength (absolute and normalized) of the external/internal rotators of the shoulder and flexor/extensor of the knee and strength derivatives, conventional strength ratio (CSR), dynamic control ratio (DCR), and bilateral deficits were measured. RESULTS: Males showed greater strength in all strength indices (P < .05). The older group had greater strength compared to younger for most of the upper and lower limb indices (P < .05); these effects diminished when using normalized data. For females, there was no age group effect in the shoulder and knee strength. All players displayed lower shoulder and knee normative values for CSR and DCR. Dominant and non-dominant knee strength were comparable between sex and age groups. CONCLUSIONS: For males, growth and maturation had a greater contribution to strength gained compared to training, whereas for females, growth, maturation, and training did not improve strength. The normalized data indicated that training did not improve all indices measured apart from external rotator strength in females. All players also displayed lower normative values of CSR and DCR. These results suggest that training in elite adolescent Malaysian badminton players lacks consideration of strength gain and injury risk factors.