Isokinetic Fatigue Protocol Research Articles

Myotendinous Thermoregulation in National Level Sprinters after a Unilateral Fatigue Acute Bout—A Descriptive Study

In the last decade there has been a growing interest in infrared thermography in the field of sports medicine in order to elucidate the mechanisms of thermoregulation. The aim of this study was to describe bilateral variations in skin temperature of the anterior thigh and patellar tendon in healthy athletes and to provide a model of baseline tendon and muscle thermoregulation in healthy sprinters following a unilateral isokinetic fatigue protocol. Fifteen healthy national-level sprinters (eleven men and four women), with at least 3 years of athletic training experience of 10–12 h/week and competing in national-level competitions, underwent unilateral isokinetic force testing and electrostimulation in which their body temperature was measured before, during, and after the protocol using an infrared thermographic camera. ANOVA detected a significant difference in the time × side interaction for patellar temperature changes (p ≤ 0.001) and a significant difference in the time/side interaction for quadriceps temperature changes (p ≤ 0.001). The thermal challenge produces homogeneous changes evident in quadriceps areas, but not homogeneous in tendon areas. These data show that metabolic and blood flow changes may depend on the physical and mechanical properties of each tissue. Future research could be conducted to evaluate the predictive value of neuromuscular fatigue in the patellar tendon and quadriceps after exercise in order to optimize post-exercise recovery strategies.

Changes in knee flexion-extension performance and hamstring-to-quadriceps ratio during a fatiguing isokinetic protocol in male professional futsal players

ABSTRACT Knee flexion (KF) and extension (KE) performance and hamstring-to-quadriceps (H:Q) ratio are used to estimate injury risk and readiness to return to sport. However, the traditional measures (i.e. non-fatigued state and by peak torque [PT]) may not reflect the thigh and knee injury conditions (i.e. high-speed actions and fatigue presence). We verified the effects of a high-speed isokinetic fatigue protocol (30 consecutive KF and KE concentric contractions at 300°/s) on KF and KE performance and H:Q ratios assessed through different parameters (i.e. PT, work, average and peak power) in male professional futsal players (n = 17). A significant (p < 0.01) time × muscle group interaction was verified. There were reductions (p < 0.01) in KF by PT (84.79 ± 15.05 to 50.29 ± 15.29 Nm), work (87.28 ± 14.46 to 39.00 ± 13.83 Nm), average power (227.81 ± 39.31 to 104.75 ± 31.24 W) and peak power (383.40 ± 59.90 to 191.39 ± 48.35 W). Similarly, KE performance decreased (p < 0.01) for all parameters (PT: 131.36 ± 16.05 to 81.61 ± 9.15 Nm; work: 148.83 ± 20.88 to 90.72 ± 11.89 Nm; average power: 148.83 ± 20.88 to 90.72 ± 11.89 W; peak power: 664.74 ± 85.32 to 398.38 ± 42.42 W). KF (−55.18 ± 13.91% to −40.94 ± 12.66%) showed a higher percentage decrease than KE (−40.46 ± 7.38% to −37.45 ± 6.61%). Finally, reductions (p < 0.01) in H:Q ratio by work, average and peak power but not by PT (p = 0.25) were verified. The tested methods can provide additional information about the athlete’s condition.

Effects of an isokinetic fatigue protocol on knee flexion–extension performance and hamstrings-to-quadriceps ratio in women professional soccer players

Effects of an isokinetic fatigue protocol on knee flexion–extension performance and hamstrings-to-quadriceps ratio in women professional soccer players

Effects of a Thorstensson fatiguing protocol on isometric and isokinetic performance

OBJECTIVE: Having participants perform 50 maximal isokinetic contractions, as introduced by Thorstensson and Karlsson (1976), is to this day one of the most commonly used fatigue protocols. Purpose: To determine to what extent a Thorstensson fatiguing protocol affects isokinetic and isometric performance characteristics. METHODS: Twenty-five college-aged men performed an isokinetic fatigue protocol consisting of 50 maximal elbow flexions at a moderate speed (180∘⋅s-1). Pre- and post-tests were used to calculate fatigue indices (FI%) for the following variables: isometric and isokinetic peak torque (PT), isometric rate of torque development (RTD), and maximum acceleration (ACCmax). RESULTS: Each of the four dependent variables significantly decreased with fatigue (each demonstrated p&lt; 0.001), but not of the same magnitude. Isometric PT FI (-18.7%) was significantly less than isokinetic PT FI (-45.1%, p⩽ 0.001) and ACCmax FI (-26.3%) was significantly less than isometric RTD FI (-54.9%, p⩽ 0.001). There was a significant positive relationship between isometric and isokinetic PT FI% (r= 0.60, p&lt; 0.002) as well as between isometric PT FI% and RTD FI% (r= 0.40, p&lt; 0.046). There was no significant relationship observed between RTD FI% and ACCmax FI% nor between isokinetic PT FI% and ACCmax FI%. CONCLUSIONS: This investigation observed different patterns of response in maximal strength between isometric and isokinetic assessments following a isokinetic fatigue protocol. Additionally, the ability to rapidly generate strength and velocity had significantly different responses to fatigue between isometric and dynamic assessments. Due to these different responses, we recommend that assessments of fatigue at least include the same testing modality as the modality of the fatigue protocol.

Does Alteration of Balance Control After Ankle Muscle Fatigue in National Judo Athletes Depend on Postural Task Difficulty?

Background: The purpose of the present study was to assess the impacts of plantar-flexors and dorsi-flexors fatigue following isokinetic contractions on postural control in nine young healthy national level judo athletes. Methods: Participants were required to stand still on a force plate with opened and closed eyes in feet together (FT) and single leg (SL) stance before (PRE) and after (POST) an isokinetic fatigue protocol. Mediolateral sway (ML sway), anteroposterior sway (AP sway), and velocity sway were calculated and used to assess the postural control. Results: Velocity sway POST was significantly (P &lt; 0.001) higher than PRE in FT stance and SL stance. Velocity sway POST was significantly higher in the SL stance than the FT stance (P = 0.01). During eyes closed, a significant interaction postural task by fatigue for all parameters was found. All parameters increased significantly after fatigue compared to PRE. After fatigue, ML sway, AP sway, and velocity sway were significantly higher for the SL stance than the FT stance. Conclusions: Ankle muscle fatigue led to reduced postural stability during different stances in young healthy judo athletes. This effect was more accentuated when vision was removed and the base of support was reduced. Alteration of postural control depended on the difficulty of the postural stance.

Does Alteration of Balance Control After Ankle Muscle Fatigue in National Judo Athletes Depend on Postural Task Difficulty?

ackground: The purpose of the present study was to assess the impacts of plantar-flexors and dorsi-flexors fatigue following isokinetic contractions on postural control in nine young healthy national level judo athletes. Methods: Participants were required to stand still on a force plate with opened and closed eyes in feet together (FT) and single leg (SL) stance before (PRE) and after (POST) an isokinetic fatigue protocol. Mediolateral sway (ML sway), anteroposterior sway (AP sway), and velocity sway were calculated and used to assess the postural control. Results: Velocity sway POST was significantly (P &lt; 0.001) higher than PRE in FT stance and SL stance. Velocity sway POST was significantly higher in the SL stance than the FT stance (P = 0.01). During eyes closed, a significant interaction postural task by fatigue for all parameters was found. All parameters increased significantly after fatigue compared to PRE. After fatigue, ML sway, AP sway, and velocity sway were significantly higher for the SL stance than the FT stance. Conclusions: Ankle muscle fatigue led to reduced postural stability during different stances in young healthy judo athletes. This effect was more accentuated when vision was removed and the base of support was reduced. Alteration of postural control depended on the difficulty of the postural stance.

Effect of laterality and fatigue in peroneal electromechanical delay.

Introduction: Extremity dominance is one of the intrinsic factors that have been identified for ankle sprains. Electromechanical delay (EMD) is an integral part of the peroneal motor response and, therefore, substantial in preventing ankle sprains. This study aimed to investigate the effect of laterality on EMD times before and after fatigue. Methods: Fifteen healthy male volunteers participated in the study. Measurements were taken with the ankle in a neutral (0°) position, and all subjects followed an isokinetic fatigue protocol. Repeated ANOVA was used for statistical analysis, and the α level was set a priori at p ≤ 0.05. Results: No significant difference was noted in EMD times between the dominant and non-dominant legs of the volunteers (p = 0.940). Fatigue caused a significant increase in EMD by 10–15 ms (p = 0.003), while the leg × fatigue interaction was not significant (p = 0.893). Conclusions: In a non-injured athlete, both ankles seem to be under the same protection of the reactive response of the peroneal muscles. Therefore, athletes should be aware that both their extremities are equally exposed to the danger of an ankle injury. Also, fatigued ankles demonstrate longer EMD times, implying that improving resistance to fatigue may add another layer of protection that has the potential to prevent ankle sprain recurrence.

Modification of Angular Kinematics and Spatiotemporal Parameters during Running after Central and Peripheral Fatigue

Fatigue causes kinematics modifications during running, and it could be related to injuries. The aim was to identify and compare the effects of central and peripheral fatigue on angular kinematics and spatiotemporal parameters during running. Angular kinematics and spatiotemporal parameters were evaluated using an infrared motion capture system and were registered during 2 min treadmill running in pre- and post-fatigue states in eighteen male recreational runners. Central fatigue was induced by a 30 min running fatigue protocol on a treadmill, while peripheral fatigue in quadriceps and hamstrings muscles was induced by an isokinetic dynamometer fatigue protocol. Central fatigue increased the anterior shank oscillation during the initial contact, knee flexion during the maximum absorption, posterior shank oscillation during propulsion, and stance time (p &lt; 0.05). Peripheral fatigue decreased ankle dorsiflexion during initial contact and increased knee flexion and posterior shank oscillation during propulsion (p &lt; 0.05). Moreover, central fatigue increased to a greater extent the hip and knee flexion and ankle dorsiflexion during initial contact and maximum absorption as well as stance time and propulsion time (p &lt; 0.05). These results suggested that central fatigue causes greater increases in the range of movements during the midstance than peripheral fatigue.

Fatigue-Induced Scapular Dyskinesis in Healthy Overhead Athletes.

Alterations of scapular kinematics affect the whole kinematic chain, potentially leading to the impingement syndrome. This is crucial in overhead sports, where athletes perform frequent and quick upper limb actions. In this manuscript, we aimed to assess the extent to which fatigue alters scapulo-thoracic and scapulo-humeral ranges of motion (RoM), as well as scapulo-humeral movement onset during different upper limb actions. Twenty-four young healthy males aged 22 ± 2 years (height: 1.82 ± 0.06 m, body mass: 78.0 ± 7.8 kg) performed three movements (upper limb elevation, scapular-plane abduction, and intra-extra rotation) before and after an isokinetic fatigue protocol (upper limb intra/extra rotation, 32 repetitions at 120 degrees/s). Pre vs. post fatigue RoM of humeral elevation and rotation, scapular retraction/protraction, and rotation and tilt were computed. Humerus-scapula movement delay was also determined. Humerus elevation range reduced during intra/extra humerus rotation in fatigued conditions (p = 0.006). Scapular tilt RoM increased after the fatigue protocol (p = 0.063, large effect). Humerus-scapular movement onset delay reduced in fatigued conditions of about 80 ms (p < 0.001, large effect). In sum, fatigued intra/extra upper limb rotators altered the scapulohumeral rhythm, and joints RoM in movements outside the scapular plane. Rather, movements close to the scapular plane were less prone to fatigue-induced alterations.

Effect of Fatigue on Functional Stability of the Knee: Particularities of Female Handball Players.

The risk of anterior cruciate ligament injury in female handball players is high. Fatigue of active stabilizers and increases in joint laxity are often mentioned in the literature as causal factors. However, no studies have been carried out on this population. Our objective is to determine the effect of muscle fatigue on active and passive knee stability in female handball players. This prospective study assessed tibiofemoral joint laxity, as well as hamstring and quadriceps strength, before (Tinitial), during and 3 min after (Tfinal) an isokinetic fatigue protocol (25 repetitions of knee flexion / extension at 180°.s-1). Laxity values (slope of the displacement-load curve and anterior tibial translation) were measured using a GNRB-Rotab® arthrometer; torque values were measured at specific joint angles and peak muscle torque using an isokinetic dynamometer. Nineteen women (20.9±2.4 years, 62.0±4.9 kg, 166±5 cm) were included. Normalized peak torque decreased significantly between the first three and last three repetitions of the fatigue protocol (p<0.0001, ES=3.2 and 3.2). Slope of the displacement-load curve and anterior tibial translation, functional and conventional ratios did not change significantly between Tinitial and Tfinal. Active and passive markers of knee stability were not altered by a fatigue protocol in female handball players, suggesting these players have a large capacity for recovery. These results suggest that muscle strengthening to prevent ACL injury in female handball players may be inappropriate.Level of evidence: Level 2b, Prospective Cohort.

Effect of Fatigue on The Neuromuscular Transmission of Hamstrings During Eccentric Muscle Action

Electromechanical delay (EMD) is a key to evaluate the ability of neuromuscular transmission, and fatigue is believed to be associated with altered neuromuscular transmission of hamstrings, which may increase the risk of non-contact anterior cruciate ligament (ACL) injury. However, experiment evidence supporting this relationship is insufficient. PURPOSE: The purpose of this study is to investigate the effect of fatigue on electromechanical delay times of hamstrings during eccentric muscle action. METHODS: Twenty female (20±2 yrs) volunteers participated in the study and EMD of semitendinosus (ST), semimembranosus (SM) and biceps femoris (BF) were determined before and after fatigue during eccentric muscle action at 120 and 240°/s. All subjects followed an isokinetic fatigue protocol until flexion torque fell below 50% of initial torque for three consecutive repetitions. A 2*2*3 ANOVA was used to calculate the effect of fatigue, movement velocity, type of muscle and their interaction on EMD. RESULTS: There was no significant difference in the EMD of the 3 muscles examined (BF: 119.0±25.3ms vs. SM: 118.9±24.0ms vs. ST: 12 0.3±24.9ms, P>0.05), irrespective of fatigue status or movement velocity. Fatigue caused a significant increase on EMD of 3 muscles examined (non-fatigue: 98.4±11.5ms vs. fatigue: 140±13.8ms, P<0.001). Irrespective of fatigue, EMD of the 3 muscles significantly increased with increasing movement velocity (low angular velocity: 107.8±20.9ms vs. high angular velocity: 131.0±22.5ms, P<0.001). CONCLUSIONS: Our findings suggest that fatigue decrease the ability of neuromuscular transmission of hamstrings during eccentric muscle action, irrespective of movement velocity. This would suggest that improving resistance to fatigue of hamstrings may be an effective prevention tool of non-contact ACL injury.

Photobiomodulation (PBM) therapy at 904nm mitigates effects of exercise-induced skeletal muscle fatigue in young women.

Muscle fatigue is a process influenced by several mechanisms such as concentration of metabolic substrates, changes in blood flow, and increases in reactive oxygen species that impair contractile muscle function. In this context, photobiomodulation has been investigated for preventing muscle fatigue, with reports of positive effects on muscle performance. This study aimed to investigate the effects of 904-nm LASER photobiomodulation on rectus femoris muscle performance in young women. Eighteen young women participated in a randomized, participant and assessor-blinded crossover trial with placebo control. Active LASER (904nm, 60mW, 250Hz, 3.6J per diode, total dose of 129.6J) intervention was applied prior to an isokinetic fatigue protocol consisting of a set of 60 concentric quadricep contractions at a constant dynamometer angular velocity of 180°/s. Compared to placebo, LASER photobiomodulation significantly reduced muscle fatigue across a range of indicators including reduced ratings of perceived exertion (P = 0.0139), and increased electromyographic fatigue index (EFI) (P = 0.005). The isokinetic dynamometer performance analysis demonstrated that LASER photobiomodulation increased peak torque (P = 0.04), time to peak torque (P = 0.042), total work (P = 0.032), average power (P = 0.0007), and average peak torque (P = 0.019) between both experimental conditions. No significant difference was observed for work fatigue index (P = 0.29) or for lactate concentration (P > 0.05). Photobiomodulation at 904nm was effective in reducing fatigue levels and increasing muscle performance in young active women but had no effect on lactate levels.

Effects of stretching and fatigue on peak torque, muscle imbalance, and stability.

The present study examined the acute effects of hamstrings stretching and fatigue on knee extension and flexion peak torque (PT), hamstrings to quadriceps (H:Q) ratio, and postural stability. Seventeen women (mean±SD age=21.8±2.1 years; body mass=63.0±10.5 kg; height=164.7±6.2 cm) and eighteen men (25.8±4.6 years; 83.6±13.2 kg; 175.3±6.0 cm) took part in three laboratory visits. The first visit was a familiarization session, and the subsequent two visits were randomly assigned as a control or stretching condition. For the testing visits, subjects performed a postural stability assessment, stretched (or sat quietly during the control condition), performed a 50-repetition unilateral isokinetic fatigue protocol, and repeated the postural stability assessment. There were no significant differences between control and stretching conditions for initial quadriceps and hamstrings PT, initial H:Q ratio, quadriceps and hamstrings PT fatigue indexes, H:Q ratio Fatigue Index, rating of perceived exertion (RPE), or postural stability (P>0.05). When analyzing 5 intervals of 10 repetitions, significant declines in quadriceps PT were found in all intervals for both conditions (P<0.05). However, a decline in hamstrings PT was only found until the fourth interval (i.e., repetitions 31 to 40) for the stretching condition (P<0.05). Stretching the hamstrings immediately prior to long-duration activities may eventually cause adverse effects in force-generating capacity of this muscle group to occur earlier when fatiguing tasks are involved. Nevertheless, no changes were found for the H:Q ratios after stretching when compared to no-stretching.

Peroneal electromechanical delay and fatigue in patients with chronic ankle instability.

The purpose of this study was to investigate the effect of chronic ankle instability (CAI) on electromechanical delay times (EMD) before and after fatigue. Understanding the mechanisms that contribute to CAI is essential for the development of effective rehabilitation programmes. It was hypothesized that patients with CAI will demonstrate prolonged EMD times compared to healthy subjects and that fatigue will cause greater increases in EMD times in the CAI group. Twenty-one male volunteers participated in the study providing data on 16 ankles with CAI and 26 with no history of ankle injury. EMD was measured on an isokinetic dynamometer. Measurements were taken with the ankle in neutral (0°) and at 30° of inversion. All subjects followed an isokinetic fatigue protocol until eversion torque fell below 50% of initial torque for three consecutive repetitions. A 2×2×2 ANOVA was used to calculate the effect of ankle status (CAI vs. healthy), fatigue, angle (0° vs. 30°) and their interactions on EMD. Fatigue caused a significant increase on EMD [non-fatigued: 122(29)ms vs. fatigue 155(54)ms; p<0.001]. EMD times were shorter at 30° of inversion compared to neutral [neutral: 145(39)ms vs. 30° of inversion: 132(40)ms, p=0.015]. An interaction effect for ankle status and angle was found (p=0.026) with CAI ankles demonstrating longer EMD [CAI: 156(45)ms vs. healthy: 133(40)ms] in neutral but not at 30° of inversion [CAI: 133(46)ms vs. 132(33)ms]. Patients with CAI had longer EMD times in neutral, but not when the ankle was placed in inversion. This suggests that rehabilitation programmes may be more effective when retraining occurs with the ankle in neutral position. It is likely that low EMD times prevent ankle acceleration at the beginning of the mechanism of injury, but they are less important when the ankle has already inverted at 30°. Both CAI and healthy subjects demonstrated longer EMD after fatigue, emphasizing the importance of proper conditioning in the prevention of delayed peroneal response and subsequent ankle injury. Improving resistance to fatigue of the peroneals may prove to be an effective prevention tool of ankle sprain recurrence in patients with CAI. III.

A potential mechanism by which torque output is preserved in cerebral palsy during fatiguing contractions of the knee extensors.

The purpose of this study was to compare agonist and antagonist electromyography (EMG) during an isokinetic fatigue protocol in subjects with cerebral palsy (CP) and typical development (TD). Nine individuals with CP and 11 with TD completed 50 repetitions of maximum concentric knee extensions (KE) and flexions (KF) at 60°/second. Rate of decline in peak torque for KE was significantly less in CP compared with TD. Rate of decline in agonist EMG was not significantly different between groups, but the rate of decline in antagonist EMG was significantly greater in CP. There were no differences between groups for KF. Declining agonist EMG occurred in parallel with declining antagonist hamstring activity in CP, decreasing the relative opposing force and resulting in a lesser decline in net torque. This finding illustrates a potential mechanism by which net torque is preserved in those with CP who are inherently weaker.

The Effect of Isolated Hamstrings Fatigue on Landing and Cutting Mechanics.

The function of the hamstrings in protecting the ACL is not fully understood. The purpose of this study was to determine how landing knee mechanics were affected by hamstrings fatigue, analyzed with principal components analysis (PCA). Knee joint mechanics were collected during single-leg stride landings that were followed by lateral and vertical jumps. An isokinetic fatigue protocol was employed to reduce hamstrings strength by 75% at the cessation of the exercise protocol. On the landing test day, participants performed the stride landing maneuvers before and after the fatigue protocol. PCA was performed on the landing knee joint angle, moment, and power waveforms, and MANOVAs were conducted on the retained PCs of each waveform (P < .05). On the strength test day, hamstrings strength recovery was assessed with an identical fatigue protocol followed by strength assessment ~75 s after the cessation of exercise. Pre- and postexercise hamstrings strength on this day was assessed with a dependent t test (P < .05). The hamstrings strength remained significantly reduced by ~8% postexercise (75 s). For stride landings followed by vertical jumps, there were significantly reduced knee flexion angles, extensor moments, and energy absorption. This was indicative of a stiffer landing strategy postfatigue, which has been associated with increased ACL loading.

Fatigue-resistance of the internal rotator muscles in the tennis player’s shoulder: Isokinetic and electromyographic analysis

Objective The main objective is to determine whether there are differences in the relative isokinetic and electromyographic responses between the internal rotator (IR) muscles on the dominant and non-dominant sides of tennis players during performance of an isokinetic fatigue protocol. Main outcome measures Ten male tennis players were recruited for this isokinetic and electromyographic study. Participants performed 35 concentric maximal voluntary actions, carrying out internal rotations of both shoulders at an angular velocity of 120° s −1. Maximal torque ( T (45°)Max), torque decrease ( T (45°)), Root Mean Square normalised (RMSnorm) and Neuromuscular Efficiency (NME) parameters were analysed. Results Although an increased T (45°)Max was observed on the dominant side compared to the non-dominant side, the progression of torque differences did not indicate differences in fatigue-resistance between the two sides. RMSnorm was also higher on the dominant side compared to the non-dominant side, without showing a fatigue effect. NME values decreased during performance of the fatigue protocol without any side effect. Conclusions Practicing tennis induces an increased T (45°)Max on the dominant side compared to the non-dominant side, but does not appear to provoke differences in the fatigue-resistance of IR muscles. EMG analysis showed that the fatigue induced was mainly peripheral (from metabolic and ionic changes).

ACTN3Genotype Does not Influence Muscle Power

The R577X polymorphism within the ACTN3 gene has been associated with elite athletic performance, strength, power, fat free mass, and adaptations to strength training, though inconsistencies exist in the literature. The specific muscle power phenotypes most influenced by the polymorphism are uncertain. The purpose of this study was to examine the association between ACTN3 R577X genotype and muscle power phenotypes. Recreationally active young men and women (N=57) were selected to complete 2 muscle performance assessments, an isokinetic fatigue protocol at testing speeds of 180° s (-1) and 250° s (-1) and a 30 s Wingate test. Isokinetic torque and Wingate power significantly decreased over the duration of each test, but no differences in the rate of decline were observed among ACTN3 genotype groups. Similarly, no significant genotype differences were observed for isokinetic peak torque, Wingate absolute or relative peak power, or fatigue index. These results indicate that in recreationally active individuals the ACTN3 R577X polymorphism is not associated with muscle performance phenotypes, supporting recent findings that R577X may only be important for predicting performance in elite athletes. Our data also indicate that using this polymorphism for genetic screening in the lay population is scientifically questionable.

Functional fatigue of the hip and ankle musculature cause similar alterations in single leg stance postural control

Isokinetic fatigue protocols have been used to determine the relative importance of lower extremity musculature to the maintenance of balance. However, these protocols are not representative of physical activity, thus the recommendations based on these findings may be inappropriate. Therefore, purpose of this investigation was to use a completely within subjects design to examine the effects of a functional ankle and hip fatigue protocol on postural control during single leg stance. All testing was completed in a health and wellness facility where 18 healthy recreationally active university students (nine female, nine male: 21.2 ± 1.96 years, 72.2 ± 17.8 kg, 170.4 ± 10.12 cm) volunteered to participate. Testing consisted of functionally fatiguing the ankle plantar flexors and dorsiflexors as well as the hip flexors and extensors. Postural control was assessed with two pre- and post-fatigue 20 s trials during single leg stance. Three measures of dynamic balance: the overall, medial/lateral, and anterior/posterior stability index were calculated using the Biodex Stability System at stability level 4. Three separate 2-way repeated measure ANOVAs indicated that fatigue of both the ankle (plantar flexors, dorsiflexors) and hip (flexors, extensors) musculature led to postural control impairments for the medial–lateral stability index ( p < 0.01), and anterior–posterior stability index ( p < 0.01). However, only ankle fatigue resulted in deficits in the overall stability index were ( p < 0.01). Furthermore, neither fatigue protocol impaired single leg stance postural control more than the other ( p > 0.05). Our results contradict previous isokinetic fatigue protocol findings, which indicate that proximal musculature fatigue results in greater postural control deficits.

The Effects of a Neoprene Knee Sleeve on Subjects With a Poor Versus Good Joint Position Sense Subjected to an Isokinetic Fatigue Protocol

It has been shown that muscle fatigue has a negative influence on proprioception. Several studies already have demonstrated improvement of proprioception by using knee sleeves. Neoprene knee sleeves have different effects on the joint position sense in locally fatigued subjects with good or poor proprioceptive acuity. A true experimental design with random assignment to intervention and control limbs. Military hospital, department of physical medicine and rehabilitation. Sixty-four healthy subjects. All subjects underwent four consecutive assessments of the same active joint-repositioning test under different conditions (braced, nonbraced, fatigued, and nonfatigued). A three-way analysis of variance with repeated-measures design was conducted to investigate the effects of side (braced versus control side), assessment sequence (one to four), and proprioceptive acuity ("good" versus "poor"), and their interactive effect on the joint position sense. Post hoc analysis revealed that only subjects with "poor" proprioceptive acuity benefit from the braced condition before the isokinetic fatigue protocol (P < 0.001). In contrast, all subjects benefit from the braced condition after the fatigue test. Bracing is helpful in individuals with a poor baseline proprioceptive acuity in both fatigued and nonfatigued states. Subjects with a good joint position sense benefit from bracing only when in a fatigued state. The present findings suggest a rationale for using neoprene knee sleeves as a preventative measure or treatment in subjects and patients to enhance proprioceptive acuity in a fatigued state. Classification into "poor" and "good" proprioceptive acuity is only relevant in the nonfatigued condition.