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PubMed1999

Co-activation of vastus lateralis and biceps femoris muscles in pubertal children and adults.

Determining the mechanisms of co-activation around the knee joint with respect to age and sex is important in terms of our greater understanding of strength development. The purpose of this study was to examine the effects of age, sex and muscle action on moment of force and electromyographic (EMG) activity of the agonist and antagonist muscle groups during isokinetic eccentric and concentric knee extension and flexion. The study comprised nine pubertal boys [mean age 12.6 (SD 0.5) years], nine girls [12.7 (SD 0.5) years] nine adult men [23.1 (SD 2.1) years] and nine adult women [23.7 (SD 3.1) years] who performed maximal isometric eccentric and concentric efforts of knee extensors and flexors on a dynamometer at 30 degrees x s(-1). The moment of force and surface EMG activity of vastus lateralis and biceps femoris muscles were recorded. The moment of force:agonist averaged EMG (aEMG) ratios were calculated. The antagonist aEMG values were expressed as a percentage of the aEMG activity of the same muscle, at the same angle, angular velocity and muscle action when the muscle was acting as agonist. Three-way analysis of variance (ANOVA) designs indicated no significant effects of age or sex on moment:aEMG ratios. Eccentric ratios were significantly higher than the corresponding concentric ones (P < 0.05). The results also indicated no significant effect of age and sex on the aEMG of the vastus lateralis and biceps femoris muscles when acting as antagonists. The antagonist aEMG was significantly greater during concentric agonist efforts compared with the corresponding eccentric ones (P < 0.05). These findings would suggest that the moment exerted per unit of agonist EMG and the antagonist activity are similar in children compared with adults and are not sex dependent. Future comparisons between eccentric and concentric moments of force and agonist ENG should take into consideration the antagonist effects, irrespective of age or sex.

Adult↗
PubMed1999

Reliability of isokinetic ankle dorsiflexor strength measurements in healthy young men and women.

The purposes of this study were: (i) to determine the test-retest reliability of isokinetic ankle dorsiflexor strength measurements in young healthy adults using the Biodex dynamometer, and (ii) to examine several statistical measures for the interpretation of reliability. Thirty men and women (mean age 23 +/- 3 years) performed three maximal concentric contractions at 30 degrees/s, 60 degrees/s, 90 degrees/s, 120 degrees/s and 150 degrees/s. Reliability of peak torque, work and torque at a specific time were assessed by calculating the intraclass correlation coefficient (ICC 2,1), Pearson product moment correlation coefficient (r), standard error of the measurement (SEM), method error (ME) and coefficient of variation (CV), and by plotting the differences between observations against their means. Isokinetic tests of ankle dorsiflexor strength in healthy young adults using the Biodex dynamometer were highly reliable (ICC 0.61-0.93). It is recommended that test-retest reliability analyses include the ICC and assessments of measurement errors (SEM, ME or CV), as well as graphs to indicate any systematic variations in the data.

Adult↗
PubMed2000

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.

Anthropometry↗
PubMed2003

[Relationship between gait speed and strength parameters in multiple sclerosis].

INTRODUCTION: Recent studies have focused on correlation between strength and gait parameters in hemiplegia, suggesting the interest for strength training in patients with central nervous system lesions. The aim of this study was to evaluate this correlation in multiple sclerosis (MS) patients with special regard to the different clinical forms including proprioceptive loss or cerebellar ataxia. PATIENTS AND METHOD: Gait speed and muscular function were performed in 27 patients with moderate affected gait (EDDS < 6). Gait speed was evaluated with Locometre and peak-torques of quadriceps and hamstrings were evaluated with isokinetic dynamometer. Patients were separated in three groups related to their deficiency: spastic group (8 patients), spastic with proprioceptive loss (12 patients) and spastic with cerebellar ataxia (7 patients). Gait parameters were evaluated in 10 healthy subjects as control group. RESULTS: Gait speeds (spontaneous and maximal) and peak torques of quadriceps and hamstring were similar in the three groups. In the whole patients group, gait speed was reduced and related to hamstring peak torque (r = 0.56 at spontaneous speed and 0.51 at high speed) but not with quadriceps peak torque. Patients with proprioceptive loss exhibited not only a higher correlation between gait speed and hamstring torque (r = 0.76 and 0.65 respectively) than other patients but also with quadriceps torque (r = 0.66 and 0.59 respectively) when patients in other groups did not. CONCLUSION: As it was previously pointed out in hemiplegic patients, MS patients exhibit some correlation between gait speed and muscle strength, mainly with hamstrings. These correlations can change in special sensory conditions suggesting that patients with sensory loss use different muscular strategies to maintain gait speed. Strength training may therefore be discussed in MS including specific modalities as a function of clinical parameters.

Biomechanical Phenomena↗
PubMed2003

Posture-dependent trunk extensor EMG activity during maximum isometrics exertions in normal male and female subjects.

Posture-dependent trunk function data are important for appropriate normalization of submaximal trunk exertions, and is also necessary to define a more precise and specific use for strength testing in the prevention and diagnosis of spinal disorders. The aim of the current study was to quantify maximal effort trunk muscle extensor activity and trunk isometric extension torque over a functional range of sagittal standing postures. Twenty healthy, young adult male and female subjects performed isometric extension tasks over a sagittal posture range of -20 degrees extension to +50 degrees flexion, in 10 degrees increments. Erector spinae muscle activity was recorded bilaterally at the level of L3 using surface EMG electrodes. Isometric trunk extension torque was measured using a trunk dynamometer. EMG and trunk torque differed significantly between genders, but there were no differences between male and female subjects when the data were normalized with respect to the upright posture. For the combined male and female population, upright posture normalized L3 EMG activity (EMGn) and trunk extension torque (Tn) increased 1.7-fold and 3.5-fold, respectively, over the 70 degrees range of sagittal postures examined. The ratio (Tn/EMGn) increased two-fold (0.83 to 1.67) from -20 degrees extension to +50 degrees flexion, indicating that the neuromuscular efficiency increases with flexion. Trunk extension torque normalized with respect to the upright posture was linearly and positively correlated (r = 0.59, P < 0.001) to similarly normalized L3 EMG activity. This relatively weak correlation suggests that trunk muscle synergism and/or intrinsic muscle length-tension relationships are also modulated by posture. This study provides data that can be used to estimate trunk extensor muscle function over a broad range of sagittal postures. Our findings indicate that appropriate postural normalization of trunk extensor EMG activity is necessary for studies where submaximal trunk exertions are performed over a range of upright postures.

Adult↗
PubMed1994

The effects of 16 months of angle-specific isometric strengthening exercises in midrange on torque of the knee extensor muscles in osteoarthritis of the knee: a case study.

Although often advocated for arthritis rehabilitation, several studies conducted on healthy subjects have demonstrated conflicting results as to whether isometric strengthening exercises performed at one joint angle can result in strength gains at other angles. The objective of this study was to determine whether midrange strength training of the quadriceps surrounding an osteoarthritic knee would increase strength in this part of the range of motion as well at other knee angles. The midrange position was chosen because the subject, a 57-year-old female with a 2-year history of moderately severe osteoarthritis of the left knee, had greatest weakness in this position. The training occurred three times per week for 16 months using a resistance training program of three sets of two maximal isometric contractions at a knee angle of 60 degrees. The dependent variable of maximal isometric knee extensor torque was recorded on an isokinetic dynamometer at knee angles of 90, 60, and 30 degrees at 6 weeks, 1 year, and 16 months. These data demonstrated a progressive torque increase at all angles over the 16-month period, with a steeper slope at the training angle. Contrary to the specificity of training concept, angle-specific strengthening in midrange may be sufficient to strengthen the extensors surrounding an osteoarthritic knee through a wide range of motion. Mid-range isometric strengthening exercises might thus prove useful in the rehabilitation of patients with knee osteoarthritis who are unable to exercise their weakened quadriceps at other angles due to pain or swelling.

Exercise Therapy↗
PubMed2002

Low bone mass in glycogen storage disease type 1 is associated with reduced muscle force and poor metabolic control.

OBJECTIVE: To study the relation between muscle force, bone mass, and metabolic control in patients with glycogen storage disease type (GSD 1). STUDY DESIGN: Distal radius bone mass and density were evaluated in 19 patients with GSD 1 (15 GSD 1a, 4 GSD 1b) by means of peripheral quantitative computed tomography. Grip force was quantified with a dynamometer. RESULTS: Height, weight, bone mass, and grip force were significantly decreased in the patients with GSD 1a, mainly as the result of low values in the poorly controlled subgroup. Boys had lower bone mass than girls. Patients with GSD 1b had higher values for bone mineral density in the trabecular compartment. In most of the study participants bone mass appeared to be adequately adapted to the mechanical requirements imposed by muscle contraction. However, 3 patients with GSD 1a had evidence for a low bone mass. CONCLUSIONS: In GSD 1, both reduced muscle strength and a direct disease effect can contribute to low bone mass. The quality of treatment is crucial to prevent disturbances in musculoskeletal development.

Adolescent↗
PubMed2002

Fatigue is not a necessary stimulus for strength gains during resistance training.

BACKGROUND: High resistance training enhances muscular strength, and recent work has suggested an important role for metabolite accumulation in this process. OBJECTIVE: To investigate the role of fatigue and metabolite accumulation in strength gains by comparing highly fatiguing and non-fatiguing isotonic training protocols. METHODS: Twenty three healthy adults (18-29 years of age; eight women) were assigned to either a high fatigue protocol (HF: four sets of 10 repetitions with 30 seconds rest between sets) to maximise metabolic stress or a low fatigue protocol (LF: 40 repetitions with 30 seconds between each repetition) to minimise changes. Subjects lifted on average 73% of their 1 repetition maximum through the full range of knee extension with both legs, three times a week. Quadriceps isometric strength of each leg was measured at a knee joint angle of 1.57 rad (90 degrees ), and a Cybex 340 isokinetic dynamometer was used to measure the angle-torque and torque-velocity relations of the non-dominant leg. RESULTS: At the mid-point of the training, the HF group had 50% greater gains in isometric strength, although this was not significant (4.5 weeks: HF, 13.3 (4.4)%; LF, 8.9 (3.6)%). This rate of increase was not sustained by the HF group, and after nine weeks of training all the strength measurements showed similar improvements for both groups (isometric strength: HF, 18.2 (3.9)%; LF, 14.5 (4.0)%). The strength gains were limited to the longer muscle lengths despite training over the full range of movement. CONCLUSIONS: Fatigue and metabolite accumulation do not appear to be critical stimuli for strength gain, and resistance training can be effective without the severe discomfort and acute physical effort associated with fatiguing contractions.

Adult↗
PubMed2000

Optimal burst duration during a facilitated quadriceps femoris contraction.

OBJECTIVE: To determine the most efficient burst duty cycle for eliciting an involuntary quadriceps femoris contraction in healthy subjects. This information will allow clinicians to make an informed decision about the optimal burst duty cycle based upon a specific treatment goal. The logical goal for such a treatment choice is to enhance motor unit recruitment in an effort to maintain postoperative or postinjury strength, when voluntary contractions may be less effective. DESIGN AND SETTING: Single-group and 5-measures design. All tests were performed in a university laboratory. SUBJECTS: Forty-eight healthy subjects (27 men and 21 women; mean age, 26.4 +/- 8.5 years) performed a maximal voluntary isometric contraction (MVIC) on an isokinetic device and received neuromuscular electrical stimulation (NMES) at 5 different burst duty cycles. MEASUREMENTS: Subjects first performed an MVIC for knee extension on an isokinetic dynamometer at 60 degrees of knee flexion. NMES surface electrodes were applied to the quadriceps muscle of each subject's dominant leg. The values for the NMES were 2500-Hz carrier frequency, 50-bursts-per-second treatment frequency, amplitude increased to maximum tolerance, and burst duty cycle set to each of the 5 comparison values. The peak isometric force generated by each of the 5 nonvolitional contractions was recorded, along with the maximal charge per burst tolerated by each subject. Force generated was described as percentage of MVIC. Efficiency was the amount of force per burst charge. RESULTS: The mean MVIC achieved by the subjects was 553.8 newtons (N). The average force per burst charge generated at 10% burst duty cycle was 132.9 N; at 30%, 104.2 N; at 50%, 93.1 N; at 70%, 52.9 N; and at 90%, 41.3 N. The average efficiency (force per millicoulombs [mC]) at 10% burst duty cycle was the highest at 6.49 N/mC and at 90% was the lowest at 1.05 N/mC. CONCLUSIONS: A burst duty cycle of 10% was the most efficient ratio of burst duration to interburst interval duration for eliciting the strongest muscle contraction. Use of this preferred duty cycle enabled only 8 of 48 subjects (16.6%) to achieve 60% MVIC within 1 trial in 1 session of NMES. Twenty-five subjects (52.0%) were able to achieve at least 10% of the MVIC in the same trial period.

Journal Article↗
PubMed1990

Effect of muscle exercise with an oral screen on lip function.

The study aimed at evaluating how training of the lips with an oral screen affects the strength of the lips and the pressure of the lips on the teeth. In addition, the effect of the treatment with an oral screen on the dentition was studied. The treatment and lip training programme was instituted for 9 months in 16 children, 7-11 years old, with protruding maxillary incisors. The effect on the dentition was studied on dental casts made before and at the end of the treatment, and 5 months thereafter, as well as on lateral cephalograms. The lip strength was recorded with a dynamometer. The pressure from the lips on the upper and lower central incisors at rest, and during chewing and swallowing was measured with an extra-oral pressure transducer incorporated in a water-filled system with an intra-oral measuring point. Measurements of lip strength and pressure were made regularly before and during the treatment, and continued for up to 10 months thereafter. The treatment resulted in a decrease of the overjet and upper dental arch length, but with some relapse after the treatment. The strength of the lips increased during the treatment, but decreased afterwards. The pressure from the lips on the teeth at rest and during swallowing was unaffected by the lip training. The pressure from the lower lip during chewing increased temporarily during the treatment period.

Cephalometry↗
PubMed1986

Thermogenesis in human skeletal muscle as measured by direct microcalorimetry and muscle contractile performance during beta-adrenoceptor blockade.

The influence of beta-adrenoceptor-blockade on skeletal muscle was studied in ten healthy males with propranolol, atenolol and pindolol randomly given for 8 days each in a cross-over double blind test. After 7 days on each drug, muscle function was tested by an isokinetic dynamometer. Thermogenesis in biopsy samples taken from vastus lateralis muscle after a low grade exercise was studied after 8 days on each drug by direct calorimetry with a perfusion microcalorimeter. Before drug administration, a median heat production rate of 0.67 mW/g of muscle was measured. This value was significantly reduced by 25% during propranolol, but no significant change was found during atenolol or pindolol administration. Peak torque decline during isokinetic endurance test changed significantly in knee flexor but not in extensor muscles, from 15% to 27% after propranolol and from 15% to 23% after pindolol. Maximum dynamic strength was unaltered. Our data suggest that blockade of sympathetic beta 2-receptors decreases thermogenesis in human skeletal muscle and impairs isokinetic endurance.

Adolescent↗
PubMedDate not supplied

A prospective evaluation of untreated acute grade III acromioclavicular separations.

We prospectively studied the natural history of untreated acute grade III acromioclavicular separations. Twenty-five patients were treated nonoperatively with a sling for comfort through progressive early range of motion as tolerated. Ten additional uninjured subjects underwent strength testing to evaluate the difference between the dominant and nondominant sides so that patient data could be standardized. The patients were examined at intervals of 6, 12, 24, 36, and 52 weeks after injury, at which time they completed a subjective questionnaire and underwent isometric dynamometer testing as well as military press and bench press strength testing. One patient underwent a surgical procedure at 2 weeks after injury because of cosmetic concerns. Twenty of the 25 patients completed the 1-year evaluation and strength-testing protocol. Subjectively, 4 of the 20 patients (20%) thought that their long-term outcome was suboptimal, although for 3 of them it was not enough to warrant surgery. Objective examination and strength testing of the 20 patients revealed no limitation of shoulder motion in the injured extremity and no difference between sides in rotational shoulder muscle strength. The bench press was the only strength test that showed a significant short-term difference, with the injured extremity being an average of 17% weaker. This study documents the natural history of patients with an untreated acute grade III acromioclavicular separation and provides a reference with which to judge all other proposed methods of treatment.

Acromioclavicular Joint↗
PubMedDate not supplied

Resection and repair for medial tennis elbow. A prospective analysis.

Fifty cases in 48 patients of intractable medial tennis elbow tendinosis (medial humeral epicondylitis) were treated surgically from 1985 to 1990 with identification and excision of the injured tendon, while retaining and closing the resection defect. All patients had symptoms that were aggravated by repetitive upper extremity activities and had failed to improve with nonoperative therapy. At surgery, the flexor carpi radialis-pronator teres interval was involved in 28 cases. Histologic examination revealed angiofibroblastic tendinosis and fibrillary degeneration of collagen. Postoperative followup averaged 37 months. An analog scale was used to analyze pain intensity, and pain occurrence was evaluated by a pain phase scale. All patients reported partial or complete pain relief postoperatively (improvement in their pain phase and pain intensity scales). Preoperatively, 14 patients had pain at rest; all 14 had relief of this pain postoperatively. Ten patients did not return to their sporting or occupational activities. Objective dynamometer strength testing revealed a significant improvement postoperatively in all patients; no major complications were seen in this series. A large percentage of patients who fail conservative treatment for medial humeral epicondylitis (tendinosis) can obtain pain relief and return to activities with the described operative technique.

Adolescent↗
PubMed1990

Hand-held compared with isokinetic dynamometry for measurement of static knee extension torque (parallel reliability of dynamometers).

The purpose of this study was to compare measurements of static knee extension torque obtained using a hand-held dynamometer (HHD) and an isokinetic dynamometer (IKD). Twenty young healthy women performed two maximum knee extension efforts against each device. The two HHD measurements did not differ significantly and were highly reliable (intraclass correlation coefficient (ICC) = 0.945). The two IKD measurements did not differ significantly and were highly reliable (ICC = 0.932). The mean of the two HHD and two IKD measurements did not differ significantly. The inter-instrument reliability was fair (ICC = 0.797). Thus, under limited circumstances the instruments may be interchangeable. The less expensive and more portable HHD may be a practical alternative for the clinical measurement of muscle strength.

Adult↗
PubMed2003

Strength increase after whole-body vibration compared with resistance training.

PURPOSE: The aim of this study was to investigate and to compare the effect of a 12-wk period of whole-body vibration training and resistance training on human knee-extensor strength. METHODS: Sixty-seven untrained females (21.4 +/- 1.8 yr) participated in the study. The whole-body vibration group (WBV, N = 18) and the placebo group (PL, N = 19) performed static and dynamic knee-extensor exercises on a vibration platform. The acceleration of the vibration platform was between 2.28 g and 5.09 g, whereas only 0.4 g for the PL condition. Vibration (35-40 Hz) resulted in increased EMG activity, but the EMG signal remained unchanged in the PL condition. The resistance-training group (RES, N = 18) trained knee extensors by dynamic leg-press and leg-extension exercises (10-20 RM). All training groups exercised 3x wk-1. The control group (CO, N = 12) did not participate in any training. Pre- and postisometric, dynamic, and ballistic knee-extensor strength were measured by means of a motor-driven dynamometer. Explosive strength was determined by means of a counter-movement jump. RESULTS: Isometric and dynamic knee-extensor strength increased significantly (P < 0.001) in both the WBV group (16.6 +/- 10.8%; 9.0 +/- 3.2%) and the RES group (14.4 +/- 5.3%; 7.0 +/- 6.2%), respectively, whereas the PL and CO group showed no significant (P > 0.05) increase. Counter-movement jump height enhanced significantly (P < 0.001) in the WBV group (7.6 +/- 4.3%) only. There was no effect of any of the interventions on maximal speed of movement, as measured by means of ballistic tests. CONCLUSIONS: WBV, and the reflexive muscle contraction it provokes, has the potential to induce strength gain in knee extensors of previously untrained females to the same extent as resistance training at moderate intensity. It was clearly shown that strength increases after WBV training are not attributable to a placebo effect.

Adolescent↗
PubMed2000

Grip-strength performances by 6- to 19-yr.-old children with and without hearing impairments.

86 children and youth enrolled at a residential school for the deaf were matched with 86 children and youth with normal hearing (by age, sex, height, weight, and hand preference) from four public schools. Each participant's grip strength was tested with a calibrated hydraulic dynamometer set at the second position. No significant between-group differences were observed. The authors attributed the similar between-group performances to the equal opportunities for participation in sport and physical education in this residential school.

Adolescent↗
PubMed2006

Influence of the muscle-tendon unit's mechanical and morphological properties on running economy.

The purpose of this study was to test the hypothesis that runners having different running economies show differences in the mechanical and morphological properties of their muscle-tendon units (MTU) in the lower extremities. Twenty eight long-distance runners (body mass: 76.8+/-6.7 kg, height: 182+/-6 cm, age: 28.1+/-4.5 years) participated in the study. The subjects ran on a treadmill at three velocities (3.0, 3.5 and 4.0 m s(-1)) for 15 min each. The V(O(2)) consumption was measured by spirometry. At all three examined velocities the kinematics of the left leg were captured whilst running on the treadmill using a high-speed digital video camera operating at 250 Hz. Furthermore the runners performed isometric maximal voluntary plantarflexion and knee extension contractions at eleven different MTU lengths with their left leg on a dynamometer. The distal aponeuroses of the gastrocnemius medialis (GM) and vastus lateralis (VL) were visualised by ultrasound during plantarflexion and knee extension, respectively. The morphological properties of the GM and VL (fascicle length, angle of pennation, and thickness) were determined at three different lengths for each MTU. A cluster analysis was used to classify the subjects into three groups according to their V(O(2)) consumption at all three velocities (high running economy, N=10; moderate running economy, N=12; low running economy, N=6). Neither the kinematic parameters nor the morphological properties of the GM and VL showed significant differences between groups. The most economical runners showed a higher contractile strength and a higher normalised tendon stiffness (relationship between tendon force and tendon strain) in the triceps surae MTU and a higher compliance of the quadriceps tendon and aponeurosis at low level tendon forces. It is suggested that at low level forces the more compliant quadriceps tendon and aponeurosis will increase the force potential of the muscle while running and therefore the volume of active muscle at a given force generation will decrease.

Adult↗
PubMed1999

Plantarflexor weakness as a limiting factor of gait speed in stroke subjects and the compensating role of hip flexors.

OBJECTIVE: To determine, using the Muscular Utilization Ratio (MUR) method, whether plantarflexor weakness is among the factors preventing stroke subjects from walking at faster speeds. Potential compensations by the hip flexors were also examined. DESIGN: A convenience sample of 17 chronic stroke subjects in a context of a descriptive study. BACKGROUND: Gait speed is correlated with the residual strength of the muscles involved in gait in stroke subjects. However, it has not been established if this residual strength limits gait speed. METHODS: Kinetic and kinematic data for comfortable and maximal gait speeds were collected on the paretic side, and were used to determine the moments in plantarflexion (mechanical demand: MUR numerator) during the push-off phase. The maximal potential moment (MUR denominator) of the plantarflexors during gait was predicted using an equation derived from dynamometric data collected with a Biodex system. The MURs of the plantarflexors were then calculated at every 1% interval of the push-off phase. The pull-off phase of gait and the hip flexor strength were also examined. RESULTS: Ten subjects of the sample had a MUR value between 80 and 150% at maximal gait speed. These subjects produced the lowest peak torques in plantarflexion. Each of the four fastest subjects of this group had a large hip flexion moment during the pull-off phase of gait and produced high hip flexion torque values on the dynamometer. Each of the seven remaining subjects had a MUR value under 70% when they walked at maximal speed. CONCLUSIONS: Weakness of the plantarflexors should be considered as one factor limiting gait speed in 10 hemiparetic subjects. Some subjects with weak plantarflexors could walk rapidly because they compensated with the hip flexors. For the remaining stroke subjects, factors other than weakness of the plantarflexors have to be considered in order to explain the reduction in their gait speed.

Adolescent↗