Differences in muscle cross-sectional area and strength between elite senior and college Olympic weight lifters

BACKGROUND: The purpose of this study was to investigate the profiles of muscle cross-sectional area (CSA) and strength capability in relation to lifting ability in Olympic weight lifters. METHODS: The subjects were 8 elite senior lifters (ESL, age=25.2+/-1.3 years, height=1.64+/-0.03 m, mass=68.6+/-4.2 kg, mean+/-SEM) and 9 college lifters (CL, 20.8+/-0.3 years, 1.67+/-0.03 m, 70.53.4 kg) whose predetermined weight classes were within the same range. The CSAs of elbow or knee extensor and elbow or knee flexor muscles were measured using a B-mode ultrasound apparatus. Concentric and eccentric maximal voluntary forces were determined with an isokinetic dynamometer at a constant velocity of 1.05 rad/sec. RESULTS: The best score of the total mass lifted in the snatch and the clean and jerk lifts was significantly higher in ESL than in CL even in terms of per unit of fat-free mass. There were no significant differences between the two groups in fat-free mass, muscle CSA and force values with the exception that ESL compared to CL showed significantly greater force in concentric knee flexion. However, the ratios of force to muscle CSA (F/CSAs) in concentric and eccentric elbow extensions, eccentric knee extension and concentric knee flexion were significantly higher in ESL than in CL. CONCLUSIONS: The present results indicated that the magnitude of muscular development in limbs was similar in elite senior and college lifters whose predetermined weight classes were within the same range. As compared to college lifters, however, elite senior lifters had a higher F/CSA in specific muscle action modes, which might relate to the optimal execution of the Olympic lifts.     

Concentric and eccentric torque comparisons for knee extension and flexion in young adult males and females using the Kinetic Communicator

The purposes of this investigation were to establish average leg torque values as a proportion of body weight for both concentric and eccentric contractions for leg extension and leg flexion, to determine leg flexion/extension ratios for both concentric and eccentric contractions, and to compare those values in males and females from ages 15 to 34 years. The Kinetic Communicator (Kin-Com, Chattecx Corp., Chattanooga, TN), a relatively new computerized strength testing device, was used so that both concentric and eccentric torques could be measured. Pilot study results indicated that Kin-Com results were reliable, r greater than 0.88. Average torque, across the full range of motion, and peak torque expressed in newton meters were divided by body weight in kilograms to produce torque values adjusted by body weight. No differences across age or sex were observed for flexion/extension ratios, but the males' weight-adjusted torque values were significantly (P less than 0.01) greater than the females'. Younger (ages 15 to 24 years) male and female subjects produced significantly (P less than 0.01) greater torque for concentric contractions than older subjects (25 to 34 years). In rehabilitation programs using the Kin-Com, the weight-adjusted torque values and flexion/extension ratios will be useful in determining patients' strength recovery from knee or leg injury and/or surgery.     

Reproducibility of isokinetic knee eccentric and concentric strength indices in asymptomatic young adults

ObjectiveTo assess the reproducibility of isokinetic eccentric and concentric knee extension and flexion strength indices obtained at two different angular velocities.DesignCohort study.SettingUniversity human performance laboratory.Participants45 healthy physically active young adults (25 males).Main outcome measuresA non reciprocal protocol of concentric and eccentric contractions of the knee extensors and flexors was performed at 30 and 120°/s. Strength indices evaluated included peak moment; dynamic control ratios; and the difference between eccentric and concentric ratio at the two angular velocities.ResultsNo evidence for inter-test bias in any of the strength indices was noted. Measurement precision for peak moment, as quantified using ratio limits of agreement, suggest that scores may be expected to vary up to 15% for the knee extensors in both eccentric and concentric contraction modes. An error of up to 19% was calculated for the peak moment scores of the knee flexors. Intraclass correlation coefficients revealed fairly robust preservation of participants’ rank order for the majority of strength indices (>0.85).ConclusionIsokinetic-related indices of knee muscles performance enable an acceptable level of detection of expected changes in muscular strength parameters as a result of planned interventions.     

Eccentric reinforcement of the ankle evertor muscles after lateral ankle sprain

To compare two methods of ankle evertor muscle reinforcement after ankle sprain: concentric vs eccentric reinforcement. Eighteen subjects practising sport with first episode of ankle sprain. The first randomized group underwent conventional physical therapy including concentric reinforcement of the evertor ankle muscles [concentric group (CG)]. The second randomized group underwent eccentric reinforcement [eccentric group (EG)]. At the end of the physical therapy, the strength of the evertor muscles was tested using an isokinetic dynamometer. The measurements were peak torques in the concentric and eccentric modes; ankle strength deficits, expressed as percentages of the healthy ankle values recorded in the concentric and eccentric modes; ratios between concentric/eccentric values. After the concentric reinforcement, in the CG group, there is both significant concentric strength deficit and an eccentric strength deficit on the injured side in comparison with the healthy side. After the eccentric reinforcement in the EG group, the muscle strength was significantly greater during concentric movements. Eccentric rehabilitation therefore restored the strength of the injured evertor muscles. These results show the value of this method, especially as the weakness of these muscles after sprains is one of the main risk factors contributing to instability and the recurrence of sprains.     

Relationships between aerobic energy cost, performance and kinematic parameters in roller ski skating

The aims of this study were to test the hypotheses that 1) the aerobic energy cost of roller ski skating (CS) is significantly related to level of performance and 2) a significant part of inter-individual differences of CS can be explained by kinematic parameters of skating locomotion. Oxygen uptake, kinematics of the knee and ankle joint, EMG of the vastus lateralis (VL) and gastrocnemius lateralis (GL) muscles, and roller ski velocity were recorded in 13 skiers who roller skied at 19.0 +/- 0.1 km x h(-1). CS was found to be 2.51 +/- 0.35 J x kg(-1) x m(-1) and significantly correlated with the skiers' level of performance (r = 0.61; p < 0.05). Significant relationships were found between CS and 1) knee angular amplitude (r = 0.75; p < 0.01) during the concentric phase, 2) VL average EMG during the concentric phase (r = 0.72; p < 0.01) and 3) VL and GL average EMG during the eccentric phase (p < 0.05). The results of this study showed that a significant part of performance could be explained by the aerobic energy cost of locomotion in skating. It can also be suggested that differences in upper/lower body utilization and/or in mechanical efficiency may explain the differences in CS.     

Effects of Kinesio tape application to trunk isokinetic strength in female participants

ABSTRACT

The purpose of this study is to analyse the effects of KT on trunk strength with respect to different angular speeds when applied to the trunks of healthy women. Forty healthy female participants were randomly distributed into two groups: the placebo group (PG) in which placebo KT was applied and the experimental group (EG). Participants’ trunk concentric flexion and extension muscle strength were measured using an isokinetic dynamometer in two different angular speeds (60°/s ? 180°/s). In both PG and EG groups, there was no significant difference measured immediately after taping at the two angular speed values. In the measurements taken 48 h later, as regards PG trunk flexion, extension muscle strength increased significantly (p = 0.0001) at 60°/sc. angular speed while, for the EG only, the strength of trunk extension muscle increased significantly (p = 0.002). It was observed, that to ensure an increase in strength, waiting for a certain length of time was required. Lower angular speeds and short-term applied KT improved the strength of the trunk extension muscle.     

The effects of strength training, cardiovascular training and their combination on flexibility of inactive older adults

The purpose of this study was to investigate the effects of aerobic training, strength training and their combination on joint range of motion of inactive older individuals. Thirty-two inactive older men (65 - 78 yr) were assigned to one of four groups (n = 8 per group): control (C), strength training (ST), cardiovascular training (CT), and combination of strength and aerobic training (SA). Subjects in the S, A, and SA trained three times a week for 16 weeks. ST included 10 resistance exercises for the major muscle groups at an intensity of 55 - 80% of 1-RM and CT included walking/jogging at 50 - 80 % of maximal heart rate. Body weight and height, physical activity level and maximal oxygen uptake (.VO(2)max) were measured before the training period. Isokinetic (60 and 180 deg x sec(-1)) and concentric strength (1-RM in bench and leg press) were assessed prior to and at the end of the training period. Hip flexion, extension, abduction, and adduction, shoulder extension, flexion, and adduction, knee flexion, elbow flexion and sit-and-reach score were determined before and at 8 and 16 weeks of training. There were no differences between groups in .VO(2)max, body weight, and height (p < 0.05). ST and SA but not CT and C increased isokinetic and concentric strength at the end of the training period (p < 0.05). ST and SA increased significantly (p < 0.05) sit-and-reach performance, elbow flexion, knee flexion, shoulder flexion and extension and hip flexion and extension both at mid- and post-training. CT increased (p < 0.05) only hip flexion and extension at post training. Results indicate that resistance training may be able to increase range of motion of a number of joints of inactive older individuals possibly due to an improvement in muscle strength.     

Functional eccentric-concentric ratio of knee extensors and flexors in pre-pubertal children, teenagers and adult males and females

The purpose of this study was to examine the age and sex associated differences in the eccentric/concentric functional ratio for the knee. Isokinetic concentric and eccentric knee extension and flexion was measured at 0.52 rad x s (-1) and 3.14 rad x s (-1) in 121 subjects. Other than mass there were no significant age-by-sex interaction effects for all variables examined. A significant velocity-by-age group effect was demonstrated for ECC (KF)/CON (KE) with higher ratios at 3.14 compared to 0.52 rad x s (-1). Females' CON (KF)/ECC (KE) was significantly lower than males at both velocities. Adults demonstrated significantly lower CON (KF)/ECC (KE) than the teenagers at 0.52 rad x s (-1) and lower than the prepubertal and teenager groups at 3.14 rad x s (-1). However, for ECC (KF)/CON (KE) at 3.14 rad x s (-1), prepubertal ratios were significantly lower than teenagers and adults. The results of the current study suggest that functional rather than conventional ratio should be used when examining knee stability. During fast velocity movements, prepubertal children have a lower capacity for generating eccentric compared to concentric torque. The lower CON (KF)/ECC (KE) ratio in adults appears to be due to a greater ability to generate large eccentric torques at all slow and fast movement velocities. The lower CON (KF)/ECC (KE) ratio in females is a product of lower concentric torque as opposed to high eccentric torque producing capability as previously thought.     

Effects of hamstring‐emphasized neuromuscular training on strength and sprinting mechanics in football players

The objective of this study was to examine the effects of a neuromuscular training program combining eccentric hamstring muscle strength, plyometrics, and free/resisted sprinting exercises on knee extensor/flexor muscle strength, sprinting performance, and horizontal mechanical properties of sprint running in football (soccer) players. Sixty footballers were randomly assigned to an experimental group (EG) or a control group (CG). Twenty‐seven players completed the EG and 24 players the CG. Both groups performed regular football training while the EG performed also a neuromuscular training during a 7‐week period. The EG showed a small increases in concentric quadriceps strength (ES = 0.38/0.58), a moderate to large increase in concentric (ES = 0.70/0.74) and eccentric (ES = 0.66/0.87) hamstring strength, and a small improvement in 5‐m sprint performance (ES = 0.32). By contrast, the CG presented lower magnitude changes in quadriceps (ES = 0.04/0.29) and hamstring (ES = 0.27/0.34) concentric muscle strength and no changes in hamstring eccentric muscle strength (ES = ?0.02/0.11). Thus, in contrast to the CG (ES = ?0.27/0.14), the EG showed an almost certain increase in the hamstring/quadriceps strength functional ratio (ES = 0.32/0.75). Moreover, the CG showed small magnitude impairments in sprinting performance (ES = ?0.35/?0.11). Horizontal mechanical properties of sprint running remained typically unchanged in both groups. These results indicate that a neuromuscular training program can induce positive hamstring strength and maintain sprinting performance, which might help in preventing hamstring strains in football players.     

Eccentric muscle action increases site-specific osteogenic response.

PURPOSE: Strain magnitude is known to be a primary determinant of the osteogenic response to loading. However, whether bone adaptation to muscle loading is determined primarily by load magnitude is unclear. The purpose of this study was to determine the contribution of load magnitude from muscle action on the site-specific osteogenic response. METHODS: Twenty young women (12 exercise, 8 control) served as subjects. Bone mineral density (BMD) of the whole body and mid-femur segment and body composition were determined by dual-energy x-ray absorptiometry. Knee extension and flexion strengths were determined on a KinCom dynamometer, with surface electromyography of the vastus lateralis muscle. Exercise subjects trained three times weekly for 18 wk on a KinCom. One leg trained using eccentric knee extension and flexion, and the opposite leg trained using concentric knee extension and flexion. RESULTS: Eccentric exercise demonstrated greater force production with lower integrated electromyographic signal (IEMG) compared with concentric exercise. Significant increases in muscle strength occurred in both exercised legs (P < 0.05), which were of similar relative change. However, only the eccentric trained leg significantly increased mid-femur segment BMD (+3.9%, P < 0.05) and mid-thigh segment lean mass (+5.2%, P < 0.05). CONCLUSIONS: These results suggest that eccentric muscle training is more osteogenic than concentric muscle training and that eccentric training is more efficient by attaining higher force production with lower IEMG.     

Kinesiophobia,but not strength is associated with altered movement in women with patellofemoral pain

BackgroundEvidence indicates the presence of both kinesiophobia and knee extension strength deficits in women with patellofemoral pain (PFP). Both impairments may contribute to apparent compensatory gait patterns including reduced cadence and peak knee flexion during stair negotiation.Research questionIs kinesiophobia or knee extension strength associated with movement pattern in women with patellofemoral pain?MethodsForty women with PFP were assessed with three-dimensional kinematic analyses during stair descent; isokinetic dynamometry of the knee extensors (isometric, concentric and eccentric); and the Tampa scale for kinesiophobia. Pearson coefficients were calculated to determine relationship among variables.ResultsKinesiophobia correlated significantly with cadence (r = −0.62, p < 0.001), and peak knee flexion (r = −0.76, p < 0.001). No significant correlations were found between any knee extensor strength variables and kinematics (cadence or peak knee flexion); or kinesiophobia (p > 0.05).SignificanceFindings of this study could suggest addressing strength impairments alone may not adequately address kinesiophobia and movement pattern impairments in women with PFP. However, high-quality randomised controlled trials are needed to test this assumption. Further value may be added if currently evidence-based knee strengthening exercise is combined with education and/or graded exposure to address kinesiophobia, and consideration to gait retraining to address altered movement patterns at the knee.     

Albuterol helps resistance exercise attenuate unloading-induced knee extensor losses

INTRODUCTION: While resistance exercise (REX) attenuates knee extensor (KE) mass and strength deficits during short-term unloading, additional treatments concurrently administered with REX are required to reduce the greater losses seen with longer periods of unloading. METHODS: To determine whether albuterol helps REX attenuate unloading-induced KE losses, two groups of subjects strength trained their left thigh three times per week, and otherwise refrained from ambulatory and weight-bearing activity for 40 d while receiving a capsule dosing treatment (albuterol, placebo) with no crossover. A third group served as unloaded controls (CTRL). On days 0, 20, and 40, the following data were collected from the nonweight-bearing (left) thigh: cross-sectional area (CSA); integrated electromyography (IEMG); and concentric and eccentric KE strength measures. Thigh CSA was estimated using anthropometric methodology. IEMG was used to provide root mean square (RMS) values from submaximal (100 nm) and maximal isometric contractions. Concentric and eccentric strength were measured from eight-repetition unilateral leg press sets. RESULTS: Repeated-measures mixed-factorial 3 x 3 ANCOVAs with day 0 values as a covariate showed group by time interactions for concentric and eccentric total work (CTW, ETW). Tukey's post hoc test showed REX-albuterol evoked significant (p < 0.05) day 40 CTW and ETW gains vs. within-group day 0 and within-time REX-placebo and CTRL values. By days 20 and 40, CTRL subjects incurred significant decrements. CONCLUSIONS: Albuterol augmented the effects of REX to increase CTW and ETW. Research identifying possible mechanisms responsible for such changes, as well as the safety of REX-albuterol administration in other models, is warranted.     

膝关节屈肌和伸肌等速向心、等速离心及等长测试的研究

本文通过运用Ｃｙｂｅｘ－６０００型等速测力系统对２５名健康男青年膝屈肌和伸肌进行等速向心、等速离心及等长测试，来比较膝肌肉向心收缩、离心收缩和等长收缩的功能，并探讨其相互间的关系。结果表明：等速测试时，膝屈肌和伸肌离心收缩的肌力明显大于向心收缩。在膝屈曲６０°时，离心收缩和等长收缩的肌力同样明显大于向心收缩，但离心收缩与等长收缩相比无显著性差异。随运动速度增加，屈肌和伸肌向心收缩的肌力明显下降，而离心收缩的肌力无明显变化。     

Effect of activation force on knee extensor torques

The purpose of this study was to determine whether the magnitude of the activation force, defined as the force that must be applied to the load cell in order to activate the resistance arm of an isokinetic dynamometer, affected knee extensor torques. Twenty-four healthy female subjects performed resisted knee extension through the range of 95 degrees to 5 degrees knee flexion, with a 5-s rest between concentric and eccentric muscle actions. Six exercise sets, composed of the combinations of activation force (20,50, and 100 N) and angular velocity (45 and 135 degrees.s-1), were randomly assigned on each of two occasions, completed within a 10-d period. Although peak torques were not affected by the activation force, average torques, eccentric torques at mid-range (50 degrees knee flexion), and torques during the initial portion of each muscle action (80 degrees knee flexion during concentric muscle actions and 20 degrees flexion during eccentric actions) increased as the activation force increased. The effect of the activation force tended to be more pronounced during eccentric than during concentric muscle actions, and at the faster angular velocity. Comparisons of torques should be based on similar test protocols, including activation force.     

恢复期脑卒中患者膝关节最大等长收缩时大腿肌群表面肌电信号特征研究

目的:探讨脑卒中恢复期偏瘫患者膝屈伸最大等长收缩(maximum isometric voluntary contraction,MIVC)时部分大腿肌肉表面肌电(surfaceelectromyography,sEMG)信号特征,为恢复期脑卒中患者的康复治疗提供客观依据。方法:28例脑卒中患者和20例年龄、性别相匹配的正常对照者。在膝关节屈伸MIVC时记录股内侧肌(vastus medialis,VM)、股直肌(rectus femoris,RF)、股外侧肌(vastus lateralis,VL)和股二头肌(biceps femoris,BF)sEMG信号,计算相应的积分肌电值(integrated EMG,iEMG)、协同收缩率(co-contraction ratio,CR)。结果:伸膝时,患侧VM、RF及VL的iEMG值显著小于正常对照及健侧iEMG(P<0.05);健侧RF的iEMG显著小于正常对照iEMG(P<0.05);屈膝时,患侧BF、VL及RF的iEMG显著小于正常对照(P<0.05)。患侧伸膝CR显著大于健侧及正常对照(P<0.05),患侧屈膝CR大于健侧及正常对照,但无统计学意义(P>0.05)。结论:恢复期脑卒中偏瘫患者双下肢肌肉收缩功能下降,患侧大腿伸肌存在轻度痉挛,肌力训练可作为患者康复训练的重点内容之一。     

Strength training and neuromuscular function in elderly people with total knee endoprosthesis

The effects of 1 year of intensive strength training on neuromuscular function were studied in elderly people operated for total endoprosthesis ( n =30) divided into 3 groups: training pup 1 (TG1, n =11), training pup 2 (TG2, n =10) and control group (CG, n =9). After the operation, TG1 and TG2 trained every second day and the training was controlled by training diaries, and CG performed only conventional exercises by themselves. The overall volume of training in TG2 was 30% greater than in TG1. Neuromuscular function was examined by measuring maximal electromyography (EMG) and maximum voluntary isometric and dynamic strength of the knee extensor and flexor muscles. The range of motion of the knee joint and the cross-sectional area (CSA) of the knee extensor muscles were also measured. After the preoperative tests, the same measurements were repeated 3, 6, 12, 24 and 52 weeks postoperatively. After the dramatic decreases in maximal isometric torque and EMG-activity during the first postoperative weeks in all groups, TG2 showed the most remarkable improvement in neuromuscular function. For instance, the maximum isometric extension torque measured at 90° knee angle increased between the 24th and 52nd weeks. The increase in the EMG-activity of the rectus femoris muscle was Significant between the 12th and 24th weeks. The CEA of the knee extensor muscles in TG2 was greater 1 year after the operation compared with the preoperative value. The intra- and extra-articular swelling of the knee joint may have irritated the free nerve endings, leading to reflex inhibition with a concomitant decrease in EMG and strength of the knee extensor muscles. Because TG2 demonstrated the most remarkable improvement in neuromuscular function after the first postoperative weeks, intensive training programs can be successfully used in rehabilitation after a major knee operation, even in elderly people.     

Isokinetic strength testing in patients with chronic heart failure--a reliability study

Measurement of skeletal muscle strength gains increasing importance as outcome parameter in patients with chronic heart failure. This study aimed at establishing short-term reliability of isokinetic strength measurements of knee extensor and flexor muscles in 38 patients with chronic heart failure. Strength tests were performed on the Cybex 6000 dynamometer. Trunk fixation was restricted to pelvic fixation. Two bouts of strength testing were performed on day 1 and one on day 5. Each isokinetic bout consisted of 3 reciprocal knee extension and flexion movements with an angular speed of 60 degrees per second. Isometric strength was measured at 30 degree knee angulation. Intraclass correlations ranged between 0.96 and 0.99 for isokinetic and isometric peak torque of knee extensor muscles and 0.82-0.96 for flexor muscles. Analysis of repeated measurements showed significant differences among the values of flexor peak torque in the isokinetic mode and between all measurements in the isometric mode (p < 0.05). Pearson's correlation coefficients for isokinetic and isometric extensor peak torques ranged between 0.95 and 0.99, for flexor peak torques between 0.81 and 0.85 (all p < 0.0001). Measurement of isokinetic knee extensor and flexor peak torque is a reliable method to assess muscle strength in patients with chronic heart failure even with altered trunk fixation.     

Electromyostimulation and plyometric training effects on jumping and sprint time

This study compared the effects of four-week training periods of electromyostimulation (EMS), plyometric training (P), or combined EMS and P training of the knee extensor muscles on 20 m sprint time (ST), jumping ability (Squat jump [SJ] and Countermovement jump [CMJ]), maximal isometric strength (MVC), and muscle cross-sectional area (CSA). Forty subjects were randomly assigned to one of the four treatment groups: electromyostimulation (EG), plyometric (PG), combined EMG, and P (EPG), that took place 4 times per week, and a control group (CG). Subjects were tested before and after the training program, as well as once more after 2 wk of detraining. A significant improvement (p < 0.05) in ST was observed after training (2.4 %) in EG while a significant slowing (p < 0.05) was observed (- 2.3 %) in EPG. Significant increases in EPG (p < 0.05) were observed in SJ (7.5 %) and CMJ (7.3 %) after training, while no significant changes in both jumps were observed after training and detraining for EG. A significant increase (p < 0.05) in MVC was observed after training (9.1 %) and after detraining (8.1 %) in EG. A significant increase (p < 0.05) in MVC was observed after training (16.3 %) in EPG. A significant increase (p < 0.01) in CSA was observed after training in EG (9.0 %) and in EPG (7.1 %). EMS combined with plyometric training increased the jumping height and sprint run in physically active men. In addition, EMS alone or EMS combined with plyometric training leads to increase maximal strength and to some hypertrophy of trained muscles. However, EMS training alone did not result in any improvement in jumping explosive strength development or even interfered in sprint run.     

Reliability and validity of the Omnitron hydraulic resistance exercise and testing device

This study assessed the measurement reliability and validity of the Hydra-Fitness Omnitron, a microprocessor-controlled isokinetic ergometer that provides concentric resistance for dynamic extension and flexion movements as well as resistance for isometric contractions. Maximal peak torque output measured by the Omnitron and strain gauge devices connected to the apparatus were compared in 26 physically active males who were tested over 3 days for isometric knee extension and isokinetic knee flexion/extension at two resistance levels. Maximal torque outputs remained stable on days 2 and 3 (p less than 0.05), and intraclass reliability yielded r = 0.94 to 0.98. There was no difference between the slopes of the regression lines for the different experimental conditions (p less than 0.05). There was significant improvement between day 1 and days 2 and 3 that corresponded to a combination of a training and learning effect. Thus, one practice session was necessary to obtain reliable individual differences. The validity correlations between peak torque output measured from the Omnitron and strain gauges were greater than r = 0.94. There was a small discrepancy (0.44 to 0.88 Nm) between the two measuring devices that can be explained by the difference in shank pad positioning that accommodates for different segment lengths. We conclude that reliability and validity were excellent over a wide range of torque outputs measured during maximal isometric and maximal dynamic double concentric flexion and extension movements.     

Facilitation of quadriceps activation is impaired following eccentric exercise

Contracting the knee flexor muscles immediately before a maximum voluntary contraction (MVC) of knee extension increases the maximal force that the extensor muscles can exert. It is hypothesized that this phenomenon can be impaired by muscle fiber damage following eccentric exercise [delayed onset muscle soreness (DOMS)]. This study investigates the effect of eccentric exercise and DOMS on knee extension MVC immediately following a reciprocal‐resisted knee flexion contraction. Electromyography (EMG) was recorded from the knee extensors and flexors of 12 healthy men during knee extension MVCs performed in a reciprocal (maximal knee extension preceded by resisted knee flexion), and nonreciprocal condition (preceded by relaxation of the knee flexors). At baseline, knee extension MVC force was greater during the reciprocal condition (P < 0.001), whereas immediately after, 24 and 48 h after eccentric exercise, the MVC force was not different between conditions. Similarly, at baseline, the EMG amplitude of the quadriceps during the MVC was larger for the reciprocal condition (P < 0.001). However, immediately after, 24 and 48 h postexercise the EMG amplitude was similar between conditions. In conclusion, eccentric exercise abolished the facilitation of force production for the knee extensors, which normally occurs when maximum knee extension is preceded by activation of the knee flexors.