Local Muscular Fatigue Research Articles

Changes in Hip Isometric Strength of Female College Soccer Players After High-Workload Training Session.

The hip adductor and abductor muscles play vital roles as stabilizers in the lower-extremity. Their activation during soccer-specific actions is essential, but local muscular fatigue can hinder athletic performance and increase the risk of injury. This study aimed to observe the variations in frontal plane hip strength in female college soccer players before and after ahigh-workload soccer-specific training session. Furthermore, the study sought to compare the relative changes in hip strength with the internal and external load measures obtained during that session. Twenty female college soccer players participated in a retrospective observational study. Isometric hip adductor and abductor strength were measured before and after a training session in the college spring season. Measurements were taken with a handheld dynamometer (MicroFET 2) while the players were supine. Global positioning system sensors (Catapult Vector S7), commonly worn by players during training sessions and competitive matches, were used to measure external and internal loads. Statistical analyses were performed using paired samples t test to assess hip adductor and abductor strength changes before and after the training session. Spearman rank was used to identify correlation coefficients between global positioning system data and isometric hip strength. The findings revealed significant decreases in the strength of the right hip adduction (P = .012, -7% relative change), right abduction (P = .009, -7.6% relative change), and left abduction (P = .016, -4.9% relative change) after the training session. Furthermore, relative decreases in hip isometric adduction and abduction strength are related to the distance covered at high speeds. The results of this study highlight that hip isometric adduction and abduction strength tend to decrease after exposure to high workloads during soccer-specific training.

Effects of Fatigue on Lower Limb Biomechanics and Kinetic Stabilization During the Tuck-Jump Assessment.

General and local muscular fatigue is postulated to negatively alter lower limb biomechanics; however, few prospective studies have been done to examine the effect of fatigue on tuck-jump performance. The tuck-jump assessment (TJA) is a criteria-based visual screening tool designed to identify neuromuscular deficits associated with anterior cruciate ligament (ACL) injury. Use of kinetics during the TJA after an intense sport-specific fatigue protocol may identify fatigue-induced neuromuscular deficits associated with ACL injury risk. To examine the effects of a sport-specific fatigue protocol on visually evidenced (2-dimensional) technical performance of repeated tuck jumps and lower limb kinetic stabilization. Cross-sectional study. Laboratory. Twelve female netball athletes (age = 20.8 ± 2.6 years, height = 170.0 ± 0.04 cm, mass = 67.5 ± 7.4 kg). Participants performed 1 set of a TJA before and after a sport-specific fatigue protocol. Paired t tests and effect sizes were used to evaluate differences and the magnitude of differences in TJA scoring criterion, kinetics, and kinetic stabilization prefatigue to postfatigue. A small increase was observed for vertical relative lower extremity stiffness postfatigue (P = .005; Hedges g = 0.45). Peak center-of-mass displacement, time of jump cycle, ground contact time, flight time, jump height, and vertical net impulse decreased with small to moderate effect sizes (P < .01; Hedges g range, 0.41-0.74). No differences were observed for TJA composite scores, peak vertical ground reaction force, and stabilization indices of kinetic variables after the fatigue protocol (P > .05). Kinetic analysis of repeated tuck jumps after a fatigue protocol identified an altered jumping strategy, which was not identifiable via visual 2-dimensional assessment. However, based on kinetic measures, fatigue induces a stiffer jumping strategy, and practitioners should consider assessing load attenuation strategies that may not be visually evident when evaluating ACL-injury risk factors in athletes who are fatigued.

Effects of Muscular Fatigue on Position Sense in Two Phases of the Menstrual Cycle.

It is generally accepted that local muscular fatigue can negatively affect position sense. Interestingly, it has been proposed that in women, position sense and neuromuscular coordination may be affected by fluctuations of estrogen and progesterone levels. The aim of this study was to examine the possible effect of localized muscle fatigue on knee joint position sense at two phases of the menses: follicular and luteal. Twenty physically active females aged 19-30 years, with normal menses, volunteered for this study. An isokinetic dynamometer was used to evaluate proprioception and perform the fatigue protocol of the knee extensors and flexors. Knee proprioception at rest and after fatigue at three knee target angles (30°, 45°, 60°) was measured. A three-way ANOVA analysis with repeated measures was performed. The results showed that the main effect of fatigue was significant, but no main effect of the menstrual cycle phase was found. Additionally, a main effect was found for the target angle (more flexed target knee joint angles were associated with larger angular error deviations). In conclusion, localized muscle fatigue can significantly reduce the accuracy of active knee joint repositioning in both the luteal and the follicular menstrual phases in young, physically active healthy women.

Dynamic muscle fatigue assessment using s-EMG technology towards human-centric human-robot collaboration

Human-centric human-robot collaboration (HHRC) allows seamless collaboration between humans and robots to fulfill flexible manufacturing operations in a shared workspace while maximizing operator autonomy and well-being toward optimal team performance. Therefore, assessing and monitoring an operator’s physical health, specifically fatigue, is paramount to maintaining a comfortable working environment. However, current fatigue assessment models are not suitable for characterizing the fatigue profile of target muscle groups against repetitive dynamic manufacturing operations non-invasively. To solve this problem, we created a theory for quantifying localized muscular fatigue by just understanding the relative task load and the number of repetitive operations the operator conducted. This was achieved by an experimentally proved multivariable linear relationship between localized muscular fatigue, task load, base muscle strength, and number of repetitive operations for an operation type via s-EMG technologies. We also showed the procedures for developing a personalized muscle fatigue profile for a variety of assembly operations via specialized s-EMG experiment design and measurement. This simple fatigue measurement mechanism allows us to constantly monitor operator fatigue via just monitoring repetitive operations conducted using non-invasive sensors, e.g., cameras. We also provide a framework for integrating our work for online fatigue monitoring in a human-robot collaboration system.

The relationship between external and internal load parameters in 3 × 3 basketball tournaments

Purpose3 × 3 basketball games are characterized by high-intensity accelerations and decelerations, and a high number of changes of direction and jumps. It is played in tournament form with multiple games per day. Therefore, optimal regeneration is crucial for maintaining a high performance level over the course of the tournament. To elucidate how load of a match affects the athletes' bodies (i.e., internal load), muscular responses to the load of 3 × 3 games were analyzed. We aimed to investigate changes in contractility of the m. rectus femoris (RF) and m. gastrocnemius medialis (GC) in response to the load of single 3 × 3 games and a 3 × 3 tournament.MethodsInertial movement analysis was conducted to capture game load in 3 × 3. Changes in contractility were measured using tensiomyography (TMG). During a two-day tournament, TMG measurements were conducted in the morning and after each game. Additionally, off-game performance analysis consisting of jump and change-of-direction (COD) tests was conducted the day before the tournament.ResultsSignificant changes of the muscle contractility were found for GC with TMG values being higher in the baseline than in the post-game measurements. In contrast to athletes of the GC group, athletes of the RF group responded with either decreased or increased muscle contractility after a single 3 × 3 game. A significant correlation between external and internal load parameters could not be shown. Concerning off-game performance, significant correlations can be reported for COD test duration, CMJ height and ∆Vc as well as COD test duration and ∆Dm. No systematic changes in muscle contractility were found over the course of the tournament in RF and GC.ConclusionThe athletes' external 3 × 3 game load and their performance level did not seem to affect muscular contractility after a single 3 × 3 game or a complete 3 × 3 tournament within this investigation. This might indicate that elite athletes can resist external load without relevant local muscular fatigue. With respect to the course of the tournament, it can therefore be concluded that the breaks between games seem to be sufficient to return to the initial level of muscle contractility.

Physiological Mechanisms of Exercise and Its Effects on Postural Sway: Does Sport Make a Difference?

While the effect of a variety of exercises on postural balance control has been extensively studied, less attention has been paid to those requiring sport-specific skills. Therefore there is a need to analyze the literature and elucidate changes in postural balance control after exercises performed in conditions close to a particular sport. This scoping review aims (i) To map the literature that addresses postural sway aspects of acute responses to general and sport-specific exercises and their underlying physiological mechanisms, and (ii) To identify gaps in the existing literature and propose future research on this topic. The main literature search conducted on MEDLINE, Web of Science, Scopus, PubMed, and Cochrane Library databases was completed by SpringerLink, Elsevier, and Google Scholar. A total of 60 articles met the inclusion criteria. Findings identified that among a variety of studies evaluating the effects of exercise on postural balance control, only few of them were conducted under sport-specific conditions (i.e., while shooting in biathlon or pentathlon, and after simulated or match-induced protocols in combat and team sports). Therefore, more research is still needed to address this gap in the literature and aim research at investigation of postural sway response to sport-specific exercises. Further analysis of the literature showed that the type, intensity and duration of exercise play a key role in increased postural sway. Whole body and localized muscular fatigue of the trunk, neck and lower limbs is considered to be a main factor responsible for the magnitude of balance impairment in an initial phase of recovery and speed of its readjustment to a pre-exercise level. Other likely factors affecting postural stability are hyperventilation and deterioration of sensorimotor functions, though some contribution of muscle damage, dehydration, hyperthermia or dizziness cannot be excluded. A better understanding of the physiological mechanisms of balance impairment after exercises performed under simulated fatigue induced protocol, close to conditions specific to a particular sport, has implications for designing smart exercise programs tailored to individual needs to improve athlete performance with high demands on postural stability and/or decrease their risk of injuries.

Role of Occupational Footwear and Prolonged Walking on Lower Extremity Muscle Activation during Maximal Exertions and Postural Stability Tasks

Background: Occupational footwear and a prolonged duration of walking have been previously reported to play a role in maintaining postural stability. The purpose of this paper was to analyze the impact of three types of occupational footwear: the steel-toed work boot (ST), the tactical work boot (TB), and the low-top work shoe (LT) on previously unreported lower extremity muscle activity during postural stability tasks. Methods: Electromyography (EMG) muscle activity was measured from four lower extremity muscles (vastus medialis (VM), medial hamstrings (MH), tibialis anterior (TA), and medial gastrocnemius (MG) during maximal voluntary isometric contractions (MVIC) and during a sensory organization test (SOT) every 30 min over a 4 h simulated workload while wearing ST, TB, and LT footwear. The mean MVIC and the mean and percentage MVIC during each SOT condition from each muscle was analyzed individually using a repeated measures ANOVA at an alpha level of 0.05. Results: Significant differences (p &lt; 0.05) were found for maximal exertions, but this was limited to only the time main effect. No significant differences existed for EMG measures during the SOT. Conclusion: The findings suggest that occupational footwear type does not influence lower extremity muscle activity during both MVIC and SOT. Significantly lower muscle activity during maximal exertions over the course of the 4 h workload was evident, which can be attributed to localized muscular fatigue, but this was not sufficient to impact muscle activity during postural stability tasks.

Brief Exercise at Work (BE@Work): A Mixed-Methods Pilot Trial of a Workplace High-Intensity Interval Training Intervention.

Introduction: The efficacy of high-intensity interval training (HIIT) for improving markers of physical fitness and cardiometabolic health is promising. The workplace is one non-laboratory setting where the effectiveness of HIIT could be explored. The aim of this study was to undertake a mixed-methods exploratory pilot trial of a workplace HIIT intervention named Brief Exercise at Work (BE@Work).Methods: Fifty-four healthy employees (mean ± standard deviation [SD] age 46 ± 10 years) from two workplaces in Northeast England were allocated to 8 weeks of thrice-weekly workplace HIIT based on boxing, stair climbing and stepping, comprising 4–7 60 s high-intensity intervals interspersed with 75 s rest (n = 30), or a no-intervention control (n = 24). The primary outcome was the change SD of predicted maximal oxygen consumption (VO2max). Markers of physical fitness, cardiometabolic health and mental well-being were also measured at baseline and follow-up. Participant perceptions of the intervention were explored in post-intervention focus groups (n = 9).Results: Mean (±SD) session attendance was 82% (±15%). Mean peak heart rate across the intervention was 87% of age-predicted maximal heart rate with a within- and between-subject SD of 5.5% and 3.7%, respectively. The SD of changes in predicted VO2max was 6.6 mL·kg−1·min−1 across both groups, which can be used to inform sample size estimations for a future full trial. The control-adjusted mean increase (95% confidence interval) in predicted VO2max was 3.9 (−0.2 to 8.1) mL·kg−1·min−1, corresponding to a Cohen's D of 0.47. We also observed preliminary evidence of small to moderate effects in favour of the intervention group for non-dominant leg extensor muscle power, markers of health-related quality of life, well-being and perceived stress and small to moderate effects in favour of the controls in perceived pain, physical activity and high-density lipoprotein cholesterol. During HIIT, focus group participants reported physiological responses they perceived as unpleasant or tiring (e.g., breathlessness, local muscular fatigue), but also that they felt alert and energised afterwards.Conclusion: The findings of this exploratory pilot trial support the implementation of a definitive randomised controlled trial to quantify the effectiveness of a workplace HIIT intervention.

Modelling muscle recovery from a fatigued state in isometric contractions for the ankle joint

Current models of localized muscular fatigue are capable of predicting performance in isometric tasks with reasonable accuracy. However, they do not account for the effect of continuously-varying task intensities on muscular recovery from a fatigued state. In this work, we propose and evaluate three continuous functions for modelling recovery to replace a dichotomous step-function in the three-compartment controller (3CC-r) model of muscle fatigue (Looft et al., 2018) and validate their predictions with previously collected data in the literature for intermittent and sustained isometric tasks of the ankle joint performed at different intensities. When compared to experimental data the accuracy of one of the three proposed models of recovery is found to be nearly the same as that yielded by the original step-function, but this seemingly-identical accuracy may be a limitation of the dataset used. A superelliptical curve relating recovery factor to task intensity is proposed to be the closest replacement for the step function as it depicts both the elevated value of recovery factor for near-rest activities as well as a nearly-constant value for low-to-high-intensity tasks.

Effects of different fatigue locations on upper body kinematics and inter-joint coordination in a repetitive pointing task.

Studies have shown that muscle fatigue can lead to posture, joint angle, inter-joint coordination and variability alterations. However, the three-dimensional kinematic effects of localized muscular fatigue on a multijoint movement remain unclear. Healthy young adults (N = 17, 10 females) performed a standing repetitive pointing task when they were non-fatigued, and after localized muscle fatigue was induced at the elbow, the shoulder, and the trunk using isometric protocols performed until exhaustion. Joint angles and angular standard deviation (SD) of trunk, shoulder and elbow, and continuous relative phase (CRP) and CRP SD between trunk and shoulder, and shoulder and elbow were computed and compared between fatigue conditions. Results showed that trunk lateral flexion SD increased after fatigue of the elbow (0.1°, p = 0.04), shoulder (0.1°, p = 0.04) and trunk (0.1°, p<0.01). However, fatigue at different muscles brought different kinematic changes. Shoulder fatigue induced the greatest overall changes, with angular changes at all three joints. Trunk fatigue increased the shoulder horizontal abduction SD, elbow flexion SD and trunk-shoulder CRP. Elbow fatigue induced angular changes at trunk, shoulder and elbow, but did not affect CRP or CRP SD. This study highlights the crucial role of trunk variability in compensating for localized muscle fatigue during a repetitive upper limb task performed while standing.

Muscle activation and local muscular fatigue during a 12-minute rotational bridge

Due to anecdotal reports of back pain during a 12-minute rotational bridge test by uniformed services, the level of fatigue leading to possible back pain and or injury was investigated. We hypothesised a high level of fatigue due to diminishing core muscle activation. Nineteen highly trained uniformed service members were measured by surface electromyography of the rectus abdominis, external oblique, internal oblique, lumbar erector spinae, thoracic erector spinae and latissimus dorsi. Average rectified electromyography amplitude (AEMG) and median power frequency were analysed to determine activation and fatigue. All AEMG were normalised and expressed as a percentage of maximal voluntary isometric contraction (%MVIC). Significant increases in AEMG were observed over the test duration for the rectus abdominis (+19.5%MVIC), external oblique (+18.0%MVIC) and internal oblique (+23.2%MVIC) during the prone position; and for the external oblique (+21.8%MVIC) when bracing on the measurement side (all, p < 0.05). No significant changes in median power frequency were observed (all, p > 0.05). Combining prone and side bridge positions is a reasonable measure of anterior, posterior and lateral trunk musculature. Muscular fatigue remained low throughout making this a safe assessment in trained individuals.

Influence of a Prolonged Tennis Match Play on Serve Biomechanics.

The aim of this study was to quantify kinematic, kinetic and performance changes that occur in the serve throughout a prolonged tennis match play. Serves of eight male advanced tennis players were recorded with a motion capture system before, at mid-match, and after a 3-hour tennis match. Before and after each match, electromyographic data of 8 upper limb muscles obtained during isometric maximal voluntary contraction were compared to determine the presence of muscular fatigue. Vertical ground reaction forces, rating of perceived exertion, ball speed, and ball impact height were measured. Kinematic and upper limb kinetic variables were computed. The results show decrease in mean power frequency values for several upper limb muscles that is an indicator of local muscular fatigue. Decreases in serve ball speed, ball impact height, maximal angular velocities and an increase in rating of perceived exertion were also observed between the beginning and the end of the match. With fatigue, the majority of the upper limb joint kinetics decreases at the end of the match. No change in timing of maximal angular velocities was observed between the beginning and the end of the match. A prolonged tennis match play may induce fatigue in upper limb muscles, which decrease performance and cause changes in serve maximal angular velocities and joint kinetics. The consistency in timing of maximal angular velocities suggests that advanced tennis players are able to maintain the temporal pattern of their serve technique, in spite of the muscular fatigue development.

Self-Reported Fatigue Does Not Highly Correlate with Objectively Measured Fatigue in Cancer Survivors

Despite its prevalence, cancer-related fatigue (CRF) is seldom assessed and treated in clinical practice. Due to the subjective and multifactorial causes of CRF, accurately assessing CRF is challenging. Self-reported measures are widely used and accepted for CRF assessment, however, these are not objective measures of fatigue. Direct assessment of fatigue through muscle function testing could provide further insight into how cancer survivors experience fatigue, which could lead to improved exercise-based interventions that target fatigue. PURPOSE: To evaluate the relationship between subjective self-reported psychometric fatigue measures and objectively-measured muscular fatigue in cancer survivors. METHODS: Cancer survivors (N = 117; ages 60 ± 13 years) were asked to complete the Revised Piper Fatigue Scale (PFS) which produces a total score and four subscale scores: behavioral/severity, affective, sensory, and cognitive/mood. A handgrip fatigue index (HFI) was determined for each participant by repetitively squeezing a handgrip dynamometer 15 times with maximal force each repetition. Participants also completed 15 maximal force knee extensions at a joint velocity of 60 deg·s-1 and a quadriceps fatigue index (QFI) was computed. Each fatigue index was computed as the difference between the average of the first two cycles and the average of the last two cycles divided by the average of the first two cycles and expressed as a percentage. RESULTS: Cancer survivors exhibited similar fatigue indices during hand grip (34±15%) and knee extension tests (35±11%) when compared with non-cancer populations from the literature. Significant relationships between the PFS total score and HFI (r2 = .120; p = .001) and the PFS sensory subscale and HFI (r2 = .143; p < .001) were observed, but less than 15% of the variance was explained in either relationship. No significant relationships were observed between PFS and QFI (p = .309). CONCLUSION: These results suggest that cancer survivors display similar rates of muscular fatigue compared with non-cancer populations and that self-reported fatigue measures are not good measures of local muscular fatigue rates in cancer survivors. As a result, subjective measures of fatigue should not be a primary determinant of the exercise dose in cancer survivors.

The Assessment of Muscular Effort, Fatigue, and Physiological Adaptation Using EMG and Wavelet Analysis.

Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) is a transcription factor co-activator that helps coordinate mitochondrial biogenesis within skeletal muscle following exercise. While evidence gleaned from submaximal exercise suggests that intracellular pathways associated with the activation of PGC-1α, as well as the expression of PGC-1α itself are activated to a greater extent following higher intensities of exercise, we have recently shown that this effect does not extend to supramaximal exercise, despite corresponding increases in muscle activation amplitude measured with electromyography (EMG). Spectral analyses of EMG data may provide a more in-depth assessment of changes in muscle electrophysiology occurring across different exercise intensities, and therefore the goal of the present study was to apply continuous wavelet transforms (CWTs) to our previous data to comprehensively evaluate: 1) differences in muscle electrophysiological properties at different exercise intensities (i.e. 73%, 100%, and 133% of peak aerobic power), and 2) muscular effort and fatigue across a single interval of exercise at each intensity, in an attempt to shed mechanistic insight into our previous observations that the increase in PGC-1α is dissociated from exercise intensity following supramaximal exercise. In general, the CWTs revealed that localized muscle fatigue was only greater than the 73% condition in the 133% exercise intensity condition, which directly matched the work rate results. Specifically, there were greater drop-offs in frequency, larger changes in burst power, as well as greater changes in burst area under this intensity, which were already observable during the first interval. As a whole, the results from the present study suggest that supramaximal exercise causes extreme localized muscular fatigue, and it is possible that the blunted PGC-1α effects observed in our previous study are the result of fatigue-associated increases in muscle acidosis. This should be explored in future research using further combinations of EMG and muscle biochemistry and histology.

The Effect Of Commonly Used Alternative Footwear On Balance

Footwear is the critical link between the human body and environment by connecting the foot to the ground surface; and different types of footwear are shown to have varying effects on human balance. PURPOSE: The purpose of this study was to examine the differences in balance prior and after a transient low intensity workload while donning three alternative footwear: crocs (CC), flip flops (FF), and vibram minimalist shoes (MIN). METHODS: Eighteen healthy male adults (age: 22.9±2.88 years; height: 179±6.0 cm; mass: 81.3±8.8 kg) participated in this study following a repeated measures design separated by a minimum of 72 hrs. Balance was assessed by the Eyes Open (EO) and Eyes Closed (EC) conditions of the Sensory Organization Test (SOT) on the Neurocom Equitest System using the equilibrium score (EQ score - higher EQ scores representing better balance) while donning alternative footwear assigned using counter-balanced measures, prior to and after a one mile walk at a self-selected pace. RESULTS: The (3×2) (Footwear × Time) repeated measures ANOVA revealed significant differences in the EO condition for main effect time (p = 0.02) and between footwear during EC condition (p = 0.003). Post-hoc pairwise comparisons using a Bonferroni correction revealed significantly lower EQ score for post-test balance compared to pre-test during EO and significantly greater EQ score for MIN compared to CC during EC. CONCLUSION: The one mile walk caused a decrement in static balance in EO, which may be attributed to the workload suggesting possible localized muscular fatigue. The results of the EC condition suggest MIN allows for greater static balance compared to CC, which may be attributed to the barefoot design feature of the minimalist shoes, suggesting a greater availability of somatosensory feedback, with no visual information.

The Energy Cost of Battle Rope Exercise

Perturbations of high intensity interval training are currently popular trends in the fitness industry. Among the more popular trends is the use of Battle Ropes (BR) to purportedly improve cardiovascular fitness, power, grip strength, fat loss and muscular endurance. Unfortunately the aforementioned claims have limited scientific support. BR exercise requires a 2.5-5 cm diameter rope ranging from 8–16 m in length, which is anchored in the middle, while the participant uses their arms to bilaterally move the finished ends of the rope up and down. PURPOSE: The purpose of this study was to determine the metabolic and cardiovascular response to performing BR exercise at movement cadences of 50 and 70 per minute. METHODS: 14 college students (7 males and 7 females, age 22.1 ±2.1 yr., ht. 1.73 ± 0.11 m, body mass 77.8 ± 17.1 kg.) performed familiarization trials followed by two different BR movement patterns consisting of an alternating-whip with trunk/hip rotation in an athletic stance (AW) and a double-whip with a simultaneous squat (DW). Each trial consisted of 10 sets of 30 sec work intervals with 60 sec recovery (14 min total) using an 11.7 m x 3.8 cm mid-anchored rope, with an additional 5 min post exercise to obtain recovery VO2. Cadences of 50 and 70 were provided by metronome and VO2 by open circuit spirometry. Lactate was obtained 3 min post-exercise. Statistical analysis by factorial ANOVA were applied to these data (p<.05). RESULTS: VO2 were 27. 2 ± 4.4, 22.4 ± 3.1, 18.3 ± 4.5 and 16.0 ± 2.7 mLO2/kg-min, heart rates were 164 ± 12.5, 152.1 ± 20.1, 131.5 ± 23.3, and 138.9 ± 23.1 b/min for the work intervals, and total caloric expenditure for the total trial plus 5 min post-trial recovery (work + recovery+ post recovery) were 169.4, 138.1, 105.0, and 93.6 kcal/trials for DW70, DW50, AW 70 and AW50 trials, respectively. The correlation between VO2 and HR for all trials was 0.46. CONCLUSION: BR exercise requires moderate energy expenditure with a disproportionate heart rate stimulus, thus precluding the use of HR as an accurate barometer of exercise intensity. The use of BR activity provides an alternative to steady state activity and provides a moderate metabolic stimulus. Due to acute local muscular fatigue of the upper body during BR, interval conditioning and a limited duration of participation are mandated for most exercise enthusiasts.

Towards Whole Body Fatigue Assessment of Human Movement: A Fatigue-Tracking System Based on Combined sEMG and Accelerometer Signals

This paper proposes a method to assess the overall fatigue of human body movement. First of all, according to previous research regarding localized muscular fatigue, a linear relation is assumed between the mean frequency and the muscular working time when the muscle is experiencing fatigue. This assumption is verified with a rigorous statistical analysis. Based on this proven linearity, localized muscular fatigue is simplified as a linear model. Furthermore, localized muscular fatigue is considered a dynamic process and, hence, the localized fatigue levels are tracked by updating the parameters with the most current surface electromyogram (sEMG) measurements. Finally, an overall fatigue level is computed by fusing localized muscular fatigue levels. The developed fatigue-tracking system is evaluated with two fatigue experiments (in which 10 male subjects and seven female subjects participated), including holding self-weight (dip start position training) and lifting weight with one arm (arm curl training).

Correlation of Heart Rate to Borg's Rating of Perceived Exertion in Indian Females using Queen's College Step Test &amp; Modified Queen's College Step Test-A Pilot Study

Background : The study was carried out to find out the correlation of heart rate to Borg's rating of perceived exertion in adult Indian females using Queen's college step test and modified Queen's college step test. Subject : 60 Adults females between the age group 20 to 40. Method : A total of 60 adult Indian females were screened for the inclusion and exclusion criteria and the endurance of subject in control group was tested using original Queen's college step test (QCT1), while that of subject in Experimental group was tested using modified Queen's college step test (QCT2). Results : Hence, in this study HR and RPE did not show correlation when QCT1 is used in adult Indian females, but HR and RPE showed significant correlation with QCT2. This could be because the height of the stool was modified (i.e. reduced by 10cm) in QCT2. The local muscular fatigue component may have got eliminated because of reduced stool height in QCT2. Conclusion : The study concludes that HR and RPE shows correlation when QCT2 is used in Indian adult female population. It also concludes that HR and RPE show no correlation when QCT1 is used in Indian adult female population.

Relationship between aerobic and anaerobic power, and Special Judo Fitness Test (SJFT) in elite Iranian male judokas

IntroductionThe purpose of this study was to assess the relationship between aerobic and anaerobic power, and special judo fitness test in elite male judokas. MethodNineteen elite Judokas [age 24.3 (3.1)yr, height 1.78 (.06) m, body mass 76.4 (11.2) kg, body mass index 20.2 (3.6)kg·m−2 and body fat 11.0 (1.8)%] performed a graded exercise test in treadmill, the Wingate anaerobic test for arms and the special judo fitness test. The graded exercise test in treadmill estimated maximal oxygen uptake (VO2max) and the Wingate anaerobic test assessed peak and mean power, descriptors of short-term power output and local muscular endurance respectively. ResultsThe index of special judo fitness test was in inverse direct relationship with VO2max (r=-.87, p<.01), peak power (r=-.74, p<.01) and mean power (r=-.62, p<.05). DiscussionBased on these findings, it was showed that the special judo fitness test is a field test that describes chiefly aerobic power, and in a lesser degree short-term power output and local muscular fatigue. Therefore, its further use from judo coaches and fitness trainers as a measure to monitor aerobic power is recommended, and the need for a field test that will describe anaerobic power is highlighted.

Shoulder muscle endurance: the development of a standardized and reliable protocol

BackgroundShoulder muscle fatigue has been proposed as a possible link to explain the association between repetitive arm use and the development of rotator cuff disorders. To our knowledge, no standardized clinical endurance protocol has been developed to evaluate the effects of muscle fatigue on shoulder function. Such a test could improve clinical examination of individuals with shoulder disorders. Therefore, the purpose of this study was to establish a reliable protocol for objective assessment of shoulder muscle endurance.MethodsAn endurance protocol was developed on a stationary dynamometer (Biodex System 3). The endurance protocol was performed in isotonic mode with the resistance set at 50% of each subject's peak torque as measured for shoulder external (ER) and internal rotation (IR). Each subject performed 60 continuous repetitions of IR/ER rotation. The endurance protocol was performed by 36 healthy individuals on two separate occasions at least two days apart. Maximal isometric shoulder strength tests were performed before and after the fatigue protocol to evaluate the effects of the endurance protocol and its reliability. Paired t-tests were used to evaluate the reduction in shoulder strength due to the protocol, while intraclass correlation coefficients (ICC) and minimal detectable change (MDC) were used to evaluate its reliability.ResultsMaximal isometric strength was significantly decreased after the endurance protocol (P < 0.001). The total work performed during the last third of the protocol was significantly less than the first third of the protocol (P < 0.05). The test-retest reliability of the post-fatigue strength measures was excellent (ICC >0.84).ConclusionsChanges in muscular performance observed during and after the muscular endurance protocol suggests that the protocol did result in muscular fatigue. Furthermore, this study established that the resultant effects of fatigue of the proposed isotonic protocol were reproducible over time. The protocol was performed without difficulty by all volunteers and took less than 10 minutes to perform, suggesting that it might be feasible for clinical practice. This protocol could be used to induce local muscular fatigue in order to evaluate the effects of fatigue on shoulder kinematics or to evaluate changes in shoulder muscle endurance following rehabilitation.