Intermuscular Coordination Research Articles

Introduction of a procedure to objectively quantify spastic movement impairment during freely performed voluntary movements

Spastic impaired limb function is a frequent result of brain lesions. Although its assessment is important for clinical and therapeutical management, it still lacks an objective measure to quantify the functionality of the affected limb. The present paper reports a procedure based on the muscular activation recorded by Surface Electromyography (sEMG), which enables the assessment of the degree of spastic impairment.15 healthy subjects and 7 patients with impaired upper limb function due to spasticity were included in the study. SEMG was recorded from the biceps and brachioradialis during active elbow extension at different movement velocities. The spastic impairment was clinically assessed by the Tardieu-Test and the Wolf Motor Function Test.Results of the clinical assessment and parameter values quantifying the muscular activation at different joint positions and movement velocities have been set in relation to one another.The results show that spastic impairment leads to a changed correlation between the muscular activation and movement velocity as well as to a changed inter-muscular co-ordination of biceps and brachioradialis. These changes, reflected in the sEMG, can be quantified by 5 newly introduced parameters. This way could allow the assessment of spastic impairment in the context of functional everyday tasks, for the first-time.

Cross-Recurrence Quantification Analysis for Inter-Muscular Coordination during Power Grip at Different Force Levels.

This study aimed to examine the dynamical coordination across muscles during power grip at different force levels. Twenty-four healthy volunteers (12 males, 12 females) participated in this experiment. Subjects were instructed to grip a hydraulic hand dynamometer and produce forces at 30%, 50%, 70% Maximal Voluntary Contractions (MVC) for at least 10s, respectively. Surface electromyography (sEMG) signals were simultaneously recorded from eight muscles, including brachioradialis (BR), flexor carpi ulnaris (FCU), flexor carpi radialis (FCR), extensor digitorum communis (EDC), flexor digitorum superficialis (FDS), abductor pollicis brevis (APB), first dorsal interosseous (FDI) and abductor digiti minimi (ADM). A cross-recurrence quantification analysis (CRQA) was applied to analyze the sEMG signals by both visualization and quantifications. Results showed that percentage of determinism (%DET) and percentage of entropy (%ENT) of the extrinsic muscle pairs were augmented with increased force levels and had a weak but positive correlation. For intrinsic muscle pairs, the %DET and %ENT increased with force levels but the difference is not or less statistically significant. These results showed that the intermuscular coordination would be alter with force output increased. For the right-handers, the values of intrinsic muscles couplings in right hand were lower than left hand, because less coupled intrinsic muscles contribute to finger dexterity; the reason why the values of extrinsic muscles couplings in right hand were greater than left hand was stronger couplings of extrinsic muscles produced higher synergistic force.

Dynamical Coordination of Hand Intrinsic Muscles for Precision Grip in Diabetes Mellitus

This study investigated the effects of diabetes mellitus (DM) on dynamical coordination of hand intrinsic muscles during precision grip. Precision grip was tested using a custom designed apparatus with stable and unstable loads, during which the surface electromyographic (sEMG) signals of the abductor pollicis brevis (APB) and first dorsal interosseous (FDI) were recorded simultaneously. Recurrence quantification analysis (RQA) was applied to quantify the dynamical structure of sEMG signals of the APB and FDI; and cross recurrence quantification analysis (CRQA) was used to assess the intermuscular coupling between the two intrinsic muscles. This study revealed that the DM altered the dynamical structure of muscle activation for the FDI and the dynamical intermuscular coordination between the APB and FDI during precision grip. A reinforced feedforward mechanism that compensates the loss of sensory feedbacks in DM may be responsible for the stronger intermuscular coupling between the APB and FDI muscles. Sensory deficits in DM remarkably decreased the capacity of online motor adjustment based on sensory feedback, rendering a lower adaptability to the uncertainty of environment. This study shed light on inherent dynamical properties underlying the intrinsic muscle activation and intermuscular coordination for precision grip and the effects of DM on hand sensorimotor function.

Coaches’ philosophies on the transfer of strength training to elite sports performance

The objective of the study was to explore coaches’ philosophies regarding strength training (repetitive muscle actions against high loads) and the transfer of strength training to sports performance. Thirteen world class coaches and athletes from track cycling, Bicycle Moto-Cross (BMX), sprint kayaking, rowing and athletics sprinting were interviewed using an open-ended, semi-structured approach. Participants were asked about their coaching philosophies, design of athlete training programmes, strength training and its transfer to sports performance. A thematic analysis was conducted. Data trustworthiness was enhanced by methods of member checking and analyst triangulation. Coaches believed that task-specific strength is essential for sports performance. They reported that non-specific strength training (‘traditional’ gym-based strength exercises that are not specific to a sport movement) is important for increasing athletes’ muscle size and strength. This is typically used in conjunction with resisted sport movement training (for example, increased resistance running, pedalling or rowing), believed to achieve an effective transfer of enhanced muscle strength to sports performance. Coaches described the transfer process as complex, with factors associated with fatigue and coordination having particular significance. The importance that coaches place on coordination is supported by a theoretical model that demonstrates increases in muscle strength from strength training may need to be accompanied with a change in inter-muscular coordination to improve sport performance. The idea that each athlete needs to adapt intermuscular coordination in response to a change in his/her unique set of ‘organism constraints’ (e.g. muscle strength) is well described by the theory of ecological dynamics and Newell’s model of constraints.

Knee extensor fatigue developed during high-intensity exercise limits lower-limb power production

ABSTRACTWe investigated the association between changes in vastii electromyography (EMG) and knee extensor fatigue during high-intensity cycling, and the subsequent effect on lower-limb power and intermuscular coordination during all-out cycling. On two separate days, participants completed 30-s all-out cycling or 10-min of high-intensity cycling followed by 30-s all-out cycling. EMG for gluteus maximus (GMAX), rectus femoris (RF), vastii (VAS), hamstrings (HAM) and gastrocnemius (GAS); co-activation for GMAX/RF, VAS/HAM and VAS/GAS; isometric maximal voluntary force (IMVF) and resting twitch (RT) of the knee extensors were measured. VAS EMG increases during high-intensity cycling (6% to 14%, P < 0.05) were negatively correlated (r = −0.791, P < 0.05) with knee extensor IMVF decreases (−2% to−36%, P < 0.05) following the exercise. Knee extensor IMVF decreases were positively correlated (r = 0.757, P < 0.05) with all-out cycling power reductions (0% to −27%, P < 0.05). VAS/GAS co-activation did not change (P > 0.05) during all-out cycling while VAS and GAS EMG decreased. Larger increase in VAS EMG during high-intensity cycling was associated with greater knee extensor fatigue and larger power reduction during all-out cycling. High VAS/GAS co-activation potentially limited power reduction induced by knee extensor fatigue during all-out cycling.

The Phenomenology of Parkinson's Disease.

The motor symptoms of Parkinson's disease are not limited to the cardinal symptoms of bradykinesia, rigidity, and resting tremor, but also include a variety of interrelated motor phenomena such as deficits in spatiotemporal planning and movement sequencing, scaling and timing of movements, and intermuscular coordination that can be clinically observed. Although many of these phenomena overlap, a review of the full breadth of the motor phenomenon can aid in the diagnosis and monitoring of disease progression.

Evidence of adaptations of locomotor neural drive in response to enhanced intermuscular connectivity between the triceps surae muscles of the rat.

The aims of this study were to investigate changes 1) in the coordination of activation of the triceps surae muscle group, and 2) in muscle belly length of soleus (SO) and lateral gastrocnemius (LG) during locomotion (trotting) in response to increased stiffness of intermuscular connective tissues in the rat. We measured muscle activation and muscle belly lengths, as well as hindlimb kinematics, before and after an artificial enhancement of the connectivity between SO and LG muscles obtained by implanting a tissue-integrating surgical mesh at the muscles' interface. We found that SO muscle activation decreased to 62%, while activation of LG and medial gastrocnemius muscles increased to 134 and 125%, respectively, compared with the levels measured preintervention. Although secondary additional or amplified activation bursts were observed with enhanced connectivity, the primary pattern of activation over the stride and the burst duration were not affected by the intervention. Similar muscle length changes after manipulation were observed, suggesting that length feedback from spindle receptors within SO and LG was not affected by the connectivity enhancement. We conclude that peripheral mechanical constraints given by morphological (re)organization of connective tissues linking synergists are taken into account by the central nervous system. The observed shift in activity toward the gastrocnemius muscles after the intervention suggests that these larger muscles are preferentially recruited when the soleus has a similar mechanical disadvantage in that it produces an unwanted flexion moment around the knee.NEW & NOTEWORTHY Connective tissue linkages between muscle-tendon units may act as an additional mechanical constraint on the musculoskeletal system, thereby reducing the spectrum of solutions for performing a motor task. We found that intermuscular coordination changes following intermuscular connectivity enhancement. Besides showing that the extent of such connectivity is taken into account by the central nervous system, our results suggest that recruitment of triceps surae muscles is governed by the moments produced at the ankle-knee joints.

Effects of Pedal Speed and Crank Length on Pedaling Mechanics during Submaximal Cycling

ABSTRACTDuring submaximal cycling, the neuromuscular system has the freedom to select different intermuscular coordination strategies. From both a basic science and an applied perspective, it is important to understand how the central nervous system adjusts pedaling mechanics in response to changes in pedaling conditions.PurposeTo determine the effect of changes in pedal speed (a marker of muscle shortening velocity) and crank length (a marker of muscle length) on pedaling mechanics during submaximal cycling.MethodsFifteen trained cyclists performed submaximal isokinetic cycling trials (90 rpm, 240 W) using pedal speeds of 1.41 to 1.61 m·s−1 and crank lengths of 150 to 190 mm. Joint powers were calculated using inverse dynamics.ResultsIncreases in pedal speed and crank length caused large increases knee and hip angular excursions and velocities (P < 0.05), whereas ankle angular kinematics stayed relatively constant (P > 0.05). Joint moments and joint powers were less affected by changes in the independent variables, but some interesting effects and trends were observed. Most noteworthy, knee extension moments and powers tended to decrease, whereas hip extension power tended to increase with an increase in crank length.ConclusionsThe distribution of joint moments and powers is largely maintained across a range of pedaling conditions. The crank length induced differences in knee extension moments, and powers may represent a trade-off between the central nervous system’s attempts to simultaneously minimize muscle metabolic and mechanical stresses. These results increase our understanding of the neural and mechanical mechanisms underlying multi-joint task performance, and they have practical relevance to coaches, athletes, and clinicians.

Susceptibility to Hamstring Injuries in Soccer

Background: Running-related hamstring strain injuries remain a delicate issue in several sports such as soccer. Their unremittingly high incidence and recurrence rates indicate that the underlying risk has not yet been fully identified. Among other factors, the importance of neuromuscular coordination and the quality of interplay between the different hamstring muscle bellies is thought to be a key determinant within the intrinsic injury risk. Muscle functional magnetic resonance imaging (mfMRI) is one of the tools that has been proven to be valid for evaluating intermuscular coordination. Purpose: To investigate the risk of sustaining an index or recurring soccer-related hamstring injury by exploring metabolic muscle characteristics using mfMRI. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 27 healthy male soccer players and 27 soccer players with a history of hamstring injuries underwent standardized mfMRI. The mfMRI protocol consisted of a resting scan, a strenuous bilateral eccentric hamstring exercise, and a postexercise scan. The exercise-related T2 change, or the signal intensity shift between both scans, was used to detect differences in metabolic characteristics between (1) the different hamstring muscle bellies and (2) the prospective cohorts based on the (re)occurrence of hamstring injuries during a follow-up period of 18 months. Results: The risk of sustaining a first hamstring injury was associated with alterations in the intermuscular hierarchy in terms of the magnitude of the metabolic response after a heavy eccentric effort, with the dominant role of the semitendinosus set aside for a higher contribution of the biceps femoris (P = .017). Receiver operating characteristic (ROC) curve analysis demonstrated that this variable was significantly able to predict the occurrence of index injuries with a sensitivity of 100% and a specificity of 70% when the metabolic activity of the biceps femoris exceeded 10%. The risk of sustaining a reinjury was associated with a substantial deficit in hamstring strength endurance (P = .031). Soccer players who sustained a reinjury were only able to perform prone leg curls for a mean duration of 146.50 ± 76.16 seconds, whereas those with an injury history but no recurrence during follow-up were able to continue for a mean of 237.45 ± 110.76 seconds (95% CI, 11.9-230.5 seconds; P = .031). Conclusion: This was the first study to assess the causal relation between the intramuscular recruitment pattern and the risk of sustaining an index or secondary hamstring strain. Changes in intermuscular interplay seem to significantly increase the risk of sustaining index hamstring injuries in male amateur soccer players. Inadequate eccentric muscle endurance could be associated with an increased risk of sustaining a recurring hamstring injury.

Effects of 5 Weeks of Bench Press Training on Muscle Synergies: A Randomized Controlled Study.

Kristiansen, M, Samani, A, Madeleine, P, and Hansen, EA. Effects of 5 weeks of bench press training on muscle synergies: A randomized controlled study. J Strength Cond Res 30(7): 1948-1959, 2016-The ability to perform forceful muscle contractions has important implications in sports performance and in activities of daily living. However, there is a lack of knowledge on adaptations in intermuscular coordination after strength training. The purpose of this study was therefore to assess muscle synergies before and after 5 weeks of bench press training. Thirty untrained male subjects were randomly allocated to a training group (TRA) or a control group (CON). After the pretest, TRA completed 5 weeks of bench press training, before completing a posttest, whereas subjects in CON continued their normal life. During test sessions, surface electromyography (EMG) was recorded from 13 different muscles. Muscle synergies were extracted from EMG data using nonnegative matrix factorization. To evaluate differences between pretest and posttest, we performed a cross-correlation analysis and a cross-validation analysis, in which the synergy components extracted in the pretest session were recomputed, using the fixed synergy components from the posttest session. Two muscle synergies accounted for 90% of the total variance and reflected the concentric and eccentric phase, respectively. TRA significantly increased 3 repetition maximum in bench press with 19.0% (25th; 75th percentile, 10.3%; 21.7%) (p < 0.001), whereas no change occurred in CON. No significant differences were observed in synergy components between groups. However, decreases in correlation values for intragroup comparisons in TRA may suggest that the synergy components changed, whereas this was not the case in CON. Strength and conditioning professionals may consider monitoring changes in muscle synergies in training and rehabilitation programs as a way to benchmark changes in intermuscular coordination.

Age- and gender-related development of stretch shortening cycle during a sub-maximal hopping task.

The aim of this study was to analyse the effects of age and gender (and their interaction) on a stretch shortening cycle solicited during a hopping task. For this aim, 147 girls and 148 boys aged 11 to 20 years, who were enrolled in middle school or secondary school with no experience in sport activity, or training less than three times per week, performed 3×5 hops in place. Leg-stiffness, jump-height and reactive-strength indices were assessed using an accelerometer (Myotest). The participants were selected in order to form five age groups: 11 12, 13-14, 15-16, 17-18 and 19-20 years. Regression analysis between force and centre of mass displacement revealed spring-mass behaviour for all groups (r2=.73-.89), meaning that beginning at the age of 11 years, children are able to perform complex inter-muscular coordination of the lower limbs, revealing efficient neural control early in childhood. Leg stiffness increased from 24.7 ± 10.6 kN · m−1 at 11-12 years to 44.1 ± 14 kN · m−1 in boys, with a small increase until 16 years (+17%) and a large increase between 17 and 20 years (+32.7%). In girls, leg stiffness increased from 26.6 ± 9 kN · m−1 at 11-12 years to 39.4 ± 10.9 kN · m−1 at 19-20 years, with a curious decrease in leg stiffness at 17-18 years, probably due to an increase in the percentage of fat at this age (25%). While no gender effect was found, the reactive-strength index revealed that, from 15-16 years onward, boys were better able to produce high levels of force in a shorter time than girls. The age of 15-16 years is a threshold of maturity and gender differentiation, where the boys investigated are more efficient in the stretch shortening cycle.

Methods of Using Innovative Game Practice in Extracurricular Physical Education of 5th-Graders

The purpose of the research is to ground the organizational and pedagogical conditions of use of innovative game practice in extracurricular physical education of 5th graders (by the example of SNAG).&#x0D; Research methods. Theoretical analysis and collation of literature sources, sociological analysis, pedagogical experiment, methods of mathematical statistics.&#x0D; Research results. The introduction of a minigolf section in the extracurricular work at Kharkiv gymnasium No. 144 brought about the 64% increase in the number of pupils of the experimantal class attending extracurricular forms of physical education, while the pupils of the reference class increased in numbers only by 7%. Some pupils attended with pleasure both the dancing club and the SNAG section.&#x0D; The results reliably showed that, compared to the beginning of the research, the experimental group manifested improvement (almost 2.5 times) of the state of special physical readiness (increased minigolf target hit rate). The indicators of the overall intermuscular coordination improved too, showing better results than in the reference group (by 15.65%) in hitting the target with a small ball (p &lt; 0,05).

Muscular coordination of biceps brachii and brachioradialis in elbow flexion with respect to hand position.

Contribution of synergistic muscles toward specific movements over multi joint systems may change with varying position of distal or proximal joints. Purpose of this study is to reveal the relationship of muscular coordination of brachioradialis and biceps brachii during elbow flexion with respect to hand position and biomechanical advantages and disadvantages of biceps brachii. A group of 16 healthy subjects has been advised to perform 20 repetitions of single elbow flexion movements in different hand positions (pronated, neutral, and supinated). With a speed of 20°/s, simultaneously sEMG of biceps brachii and brachioradialis and kinematics of the movement were recorded in a motion analysis laboratory. Normalized to MVC the sEMG amplitudes of both muscles contributing to elbow flexion movements were compared in pronated, supinated, and neutral hand position over elbow joint angle. Significant differences in the contribution of brachioradialis were found in pronated hand position compared to supinated and neutral hand position while the muscular activity of biceps brachii shows no significant changes in any hand position. In conclusion, a statistical significant dependency of the inter-muscular coordination between biceps brachii and brachioradialis during elbow flexion with respect to hand position has been observed depending on a biomechanical disadvantage of biceps brachii.

Physiological basis of the improvement of movement accuracy on the basis of stabilographic training with biological feedback

We studied the physiological parameters of ball hitting by volleyball players in unsupported position and opportunities for their improvement by training with biological feedback. Physiological and biomechanical parameters of a direct attack hit from supported position correlate with biomechanical features ofjump shots. At the same time, the physiological basis of accuracy of shots consists of the improvement of trunk and arm movement coordination in the flight phase, the factors of intramuscular and intermuscular coordination of the hitting arm and the change in the displacement of the center of pressure. The use of computer stabilography training with biological feedback helps to optimize physiological and biomechanical parameters of physical actions in unsupported position, which ultimately causes an increase in the accuracy of jump hitting of the ball. The obtained results open the prospects for applying the method of computer stabilography to improve the performance of accuracy-targeted actions in unsupported position in various sports.

Influence of Hypoxia on Joint Action Powers during Exhaustive Cycling

The relative contribution of lower-limb muscle groups changes throughout exhaustive cycling exercise. This suggests that exercise-induced fatigue is muscle group specific. We reasoned that the additional muscular distress associated with hypoxia would alter the muscle-specificity of fatigue during exercise. PURPOSE: To determine the influence of hypoxia on joint action powers across the lower-limb during exhaustive cycling. METHODS: Nine male cyclists (mean ± SD VO2MAX 61.2 ± 3.8 ml/kg/min) pedalled to the limit of tolerance at a fixed work rate (60% of the difference between VO2MAX and gas-exchange threshold: 306 ± 14 W) and fixed cadence (88 ± 2 rpm) in two conditions: normoxia (FIO2 0.21, SaO2 95 ± 1%) and hypoxia (FIO2 0.15, SaO2 85 ± 2%). Simultaneous measurements of pedal force and joint kinematics were made for each condition. Joint-specific action powers (hip extension, hip flexion, knee extension, knee flexion, plantarflexion and dorsiflexion) were derived using inverse dynamics. Each variable was averaged during the first, middle and final 30 s of exercise for each condition. Joint action powers during normoxia were also averaged across the time periods corresponding to the hypoxic condition to allow for a normoxia-isotime comparison. RESULTS: Exercise time was reduced in hypoxia (4.1 ± 0.2 vs. 10.1 ± 1.1 min, P < 0.05). In normoxia, knee extension power and ankle plantarflexion power during the final 30 s of exercise were reduced (87 ± 4% and 92 ± 2%, respectively; P < 0.05), whereas hip extension power was increased (127 ± 4%, P < 0.05). Knee extension power during the final 30 s of exercise was reduced in hypoxia and normoxia-isotime (92 ± 4% and 94 ± 3%, respectively; P < 0.05), whereas hip extension power was increased (113 ± 5% and 109 ± 2%, respectively; P < 0.05). The changes in joint action powers were not different for hypoxia vs. normoxia-isotime (P > 0.05). CONCLUSION: The hip extensors play an important role in producing additional power when other muscle groups are fatiguing during exhaustive cycling exercise. The additional muscular distress associated with hypoxia does not appear to influence inter-muscular coordination strategies.

Lower Extremity Stiffness

This article reviews research to date on lower extremity stiffness relative to its effects on performance and injury. Evidence suggests that an optimal amount of lower extremity stiffness is required for successful athletic performance, as too much or too little can be detrimental and possibly injury inducing. Methods of measuring lower extremity stiffness and fast stretch-shortening cycle performance are suggested. In terms of training, it is recommended that a combination of strength and plyometric training be performed, as well as correct execution of landing mechanics to improve intermuscular coordination and to avoid injury-provoking dominant agonist-to-antagonist coactivation ratios.

Determinants of performance when the Counter Movement Jump performs in acute fatigue

DOI: http://dx.doi.org/10.5007/1980-0037.2014v16n3p316 This work analysed the changes that occur in kinetic-temporal parameters and the electromyographic activity of lower limb muscles during the performance of maximum Counter Movement Jumps (CMJ) done with and without muscular fatigue, to explain the changes in performance in both situations. The vertical strength of fifty jumps performed by ten male sportsmen before and after a fatigue protocol was registered. Records of surface electromyography were obtained for six lower limb muscles; in addition, activation level and intermuscular coordination were analysed. For analysis purposes, negative and positive mechanic working times were considered separately. In both conditions, the temporal course of strength distribution is more important for the performance than any other instantaneous parameter. The negative external working time was significantly lower in fatigue conditions. The electromyographic analysis showed an increase in the activation level of all muscles studied and significant changes in the activation sequence. The specific kinetic-temporal variables were not good predictors of jump height. When CMJ is performed without muscle fatigue, a high value of active state favours the positive work. During fatigue, there could be a partial compensation of the performance due to the increasing activity of the contractile elements, although the activation sequence undergoes significant changes. Thus, the changes in performance would be mainly associated with the decrease in the capacity to transmit power in the proximal-distal direction.

Fatores determinantes do rendimento quando o Counter Movement Jump se realiza em fadiga aguda

This work analysed the changes that occur in kinetic-temporal parameters and the electromyographic activity of lower limb muscles during the performance of maximum Counter Movement Jumps (CMJ) done with and without muscular fatigue, to explain the changes in performance in both situations. The vertical strength of fifty jumps performed by ten male sportsmen before and after a fatigue protocol was registered. Records of surface electromyography were obtained for six lower limb muscles; in addition, activation level and intermuscular coordination were analysed. For analysis purposes, negative and positive mechanic working times were considered separately. In both conditions, the temporal course of strength distribution is more important for the performance than any other instantaneous parameter. The negative external working time was significantly lower in fatigue conditions. The electromyographic analysis showed an increase in the activation level of all muscles studied and significant changes in the activation sequence. The specific kinetic-temporal variables were not good predictors of jump height. When CMJ is performed without muscle fatigue, a high value of active state favours the positive work. During fatigue, there could be a partial compensation of the performance due to the increasing activity of the contractile elements, although the activation sequence undergoes significant changes. Thus, the changes in performance would be mainly associated with the decrease in the capacity to transmit power in the proximal-distal direction.

Method-related principles of strength conditioning for attaining positive transfer of training

The aim of the current study was to analyse the method-related principles of applying different means of strength training and correspondence to attaining positive transfer of training. We applied a logical-analytical approach that is based on different concepts of strength conditioning, documented experience of elite athletes, and coaches and internationally published research data. Experience gained by top coaches and research prove that the development of strength abilities has to begin with developing muscle elasticity and inter-muscular coordination, followed by the influencing of intramuscular coordination, with the main focus on increasing the maximal muscle strength on account of hypertrophy or fast innervations. The logical sequences of developing strength abilities in annual training cycle recommended by different authors provide thought-provoking ideas for programming appropriate training patterns, bearing in mind the general principles of the transfer of training.

The influence of locomotor rehabilitation on module quality and post-stroke hemiparetic walking performance

Recent studies have suggested the biomechanical subtasks of walking can be produced by a reduced set of co-excited muscles or modules. Individuals post-stroke often exhibit poor inter-muscular coordination characterized by poor timing and merging of modules that are normally independent in healthy individuals. However, whether locomotor therapy can influence module composition and timing and whether these improvements lead to improved walking performance is unclear. The goal of this study was to examine the influence of a locomotor rehabilitation therapy on module composition and timing and post-stroke hemiparetic walking performance.Twenty-seven post-stroke hemiparetic subjects participated in a 12-week locomotor intervention incorporating treadmill training with body weight support and manual trainers accompanied by training overground walking. Electromyography (EMG), kinematic and ground reaction force data were collected from subjects both pre- and post-therapy and from 19 age-matched healthy controls walking on an instrumented treadmill at their self-selected speed. Non-negative matrix factorization was used to identify the module composition and timing from the EMG data. Module timing and composition, and various measures of walking performance were compared pre- and post-therapy.In subjects with four modules pre- and post-therapy, locomotor training resulted in improved timing of the ankle plantarflexor module and a more extended paretic leg angle that allowed the subjects to walk faster and with more symmetrical propulsion. In addition, subjects with three modules pre-therapy increased their number of modules and improved walking performance post-therapy. Thus, locomotor training has the potential to influence module composition and timing, which can lead to improvements walking performance.