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PubMed1996

Segmental sensory innervation of the anterior cruciate ligament and the patellar tendon of the cat's knee.

We performed a study in cats to describe and quantify the segmental sensory innervation of the anterior cruciate ligament of the knee. We also studied the patellar tendon to show that transport occurs from an extraarticular, dense connective tissue structure and to obtain comparable quantitative information. We injected a tracer (horseradish peroxidase HRP, coupled to wheat germ agglutinin WGA) in the anterior cruciate ligament and observed the reaction product in the articular nerves of the injected knee and in the cell bodies of ipsilateral dorsal root ganglia. In these experiments, we found an average of 26 (13-52) labeled neurons, mostly large, after injecting the anterior cruciate. More than half of the labeled neurons were found in the dorsal root ganglion of L7 (last lumbar segment in the cat). We counted an average of 204 (17-426) labeled neurons, mostly small, after injecting the patellar tendon. More than half of these labeled neurons were found in the L5 spinal ganglion. No product was observed in contralateral spinal ganglia. Surgical ablation of the medial and lateral articular nerves (MAN and LAN) before injecting HRP-WGA in the anterior cruciate ligament, showed that the remaining afferents in the posterior articular nerve (PAN) projected mainly to L7. After excision of PAN, the projection was maintained through MAN and LAN, mostly to L5. Our quantitative data show that the anterior cruciate ligament is poorly innervated, if compared to the patellar tendon. The anterior cruciate segmental sensory innervation is directed to L7 (corresponding to the main ventral root forming the sciatic nerve in the cat), but also to L5 and L6 (main femoral nerve ventral roots). These segmental data indicate that anterior cruciate innervation influences muscle tone regulation, not only of the hamstrings (neuromuscular system of the sciatic nerve), but also of the quadriceps muscle (neuromuscular system of the femoral nerve).

Animals↗

PubMed1991

[Congenital facioscapulohumeral muscular dystrophy associated with tongue atrophy and sensorineural hearing disturbance].

An 18-year-old high-school boy presented facial muscle weakness since birth, and then developed wasting around the neck, shoulder girdle, upper arms, and thighs. He was born to un-consanguineous parents. His father had suffered from similar but milder muscle atrophy with predominance on the right side of the face and shoulder girdle since adolescence. His mother and his only sibling were clinically unaffected. Hearing disturbance was detected at the age of 6, and he also noted atrophy of the tongue and the bilateral thighs at the age of 10. The symptom progressed gradually. Neurological examination on admission revealed a well-developed boy (166 cm/60 kg) with a prominent facial diplegia with distinct proximal muscular atrophy of the extremities. Muscles of the tongue, neck, upper arms, shoulder and pelvic girdles, and hamstrings were markedly involved. The anterior tibial muscles were also affected, while the calf muscles were hypertrophic. High arched palate, X legs, mild lordoscoliosis were also noted. Serum CK was slightly increased (424 IU/l), and needle EMG in the extremities including the tongue revealed myopathic changes. Muscle CT demonstrated marked atrophy of the proximal muscles in the lower limbs and hypertrophy of the calf muscles. Audiogram showed bilateral sensorineural hearing disturbance. Muscle biopsy of the gastrocnemius showed myogenic as well as neurogenic changes consisting of atrophic and hypertrophic fibers with interstitial cellular infiltration, and type I fiber predominance. With these family history as well as clinical and laboratory examinations, this case could be diagnosed as "congenital facioscapulohumeral muscular dystrophy".(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2003

Effect of pedaling exercise on the hemiplegic lower limb.

OBJECTIVE: To assess the effects of pedaling exercise on the muscle activities in hemiparetic lower limbs in patients with stroke. DESIGN: In this before-and-after trial, 17 nonambulatory patients with chronic hemiparetic stroke were recruited. Using a servo-dynamically controlled ergometer with a trunk support, the patients pedaled at a resistance of 5 N-m at their comfortable speeds. Muscle activities were recorded with surface electrodes from bilateral quadriceps femoris, medial hamstrings, tibialis anterior, and medial gastrocnemius, and integrated electromyograms were used for analysis of muscle activity patterns during the pedaling cycle. Muscle activities during pedaling were compared with those during voluntary knee extension of the affected limb before, immediately after, and 30 min after the pedaling. RESULTS: We found phasic muscle activities in the affected limb during pedaling that were antiphasic to the contralateral side. The muscle activities of quadriceps femoris and tibialis anterior increased significantly during pedaling compared with those during voluntary knee extension effort, whereas the muscle activity of medial hamstrings did not change. The postpedaling facilitation of quadriceps and tibialis anterior and the inhibition of gastrocnemius during voluntary knee extension effort lasted at least for 30 min. CONCLUSION: Pedaling could facilitate phasic and coordinated muscle activities even in patients with severe hemiparesis, and it is potentially an effective mode of muscle reeducation.

Adult↗

PubMed1997

Fatigue after eccentric quadriceps femoris work produces earlier gastrocnemius and delayed quadriceps femoris activation during crossover cutting among normal athletic women.

Athletic women are at greater risk of anterior cruciate ligament (ACL) injury than men. Twenty, healthy, athletic women were evaluated for the effect of preferred stance limb isokinetic quadriceps femoris and hamstring fatigue from eccentric work compared with controls on the activation onset of vastus medialis, rectus femoris, vastus lateralis, the medial hamstrings, biceps femoris, and gastrocnemius muscles. Following 3 weeks of crossover cut training, subjects were tested for fatigue effects (5 subjects/week, 3 conditions, 1 condition/day, order effect controlled) on muscle activation onsets prior to crossover cut landing heelstrike (mixed model, ANOVA, P < 0.05). Fatigue from eccentric quadriceps femoris work produced delayed vastus medialis (P = 0.03), rectus femoris (P = 0.007), and vastus lateralis (P = 0.03) activation onsets compared with control, but did not differ compared to hamstring fatigue. Neither hamstring nor quadriceps femoris fatigue produced differences (P > 0.05) in medial hamstring or biceps femoris activation onsets compared to control. Quadriceps femoris fatigue from eccentric work produced earlier gastrocnemius activation onsets (P = 0.048) than control, but did not differ for hamstring fatigue. The gastrocnemius appears to provide synergistic and compensatory dynamic knee stabilization in closed kinetic chain function during quadriceps femoris fatigue. This finding in a normal group at high risk of ACL injury while performing a maneuver with a high ACL injury risk supports gastrocnemius inclusion in knee rehabilitation and conditioning programs and suggests the need for comparative evaluations of knee injured/reconstructed subjects.

Analysis of Variance↗

PubMed2004

Analysis of sEMG during voluntary movement--Part II: Voluntary response index sensitivity.

In this paper, a method for analyzing surface electromyographic (sEMG) data recorded from the lower-limb muscles of incomplete spinal-cord injured (iSCI) subjects is evaluated. sEMG was recorded bilaterally from quadriceps, adductor, hamstring, tibialis anterior, and triceps surae muscles during voluntary ankle dorsiflexion performed in the supine position as part of a comprehensive motor control assessment protocol. Analysis of the sEMG centered on two features, the magnitude of activation and the degree of similarity [similarity index (SI)] of the sEMG distribution to that of healthy subjects performing the same maneuver (n = 10). The analysis calculations resulted in response vectors (RV) that were compared to healthy-subject-derived prototype response vectors resulting in a voluntary response index (VRI). Incomplete SCI subjects (n = 9) were used to test the sensitivity of this analysis method. They were given supported-weight treadmill ambulation training, which is expected to improve or at least not cause a deterioration of voluntary motor control. The VRI provided evidence that the quantitative sEMG analysis method used was able to differentiate between healthy subjects and those with iSCI, characterize individual differences among iSCI subjects, and track motor control changes occurring over time.

Adult↗

PubMed2005

Electromyographic evaluation of the sound and involved side during gait of spastic hemiplegic children with cerebral palsy.

The purpose of this study was to investigate the surface electromyogram (EMG) of the lower limbs of hemiplegic children with spastic cerebral palsy during gait. The EMG of seven muscles was analyzed for 17 children (5-12 years old). The EMG of the involved side was decreased for the examined shank muscles and increased for the hamstrings, during certain phases of the gait cycle, compared with the sound side. The rectus femoris of the involved side showed prolonged activation during the swing phase. The enhanced activation of the hamstrings may be beneficial/compensatory, preventing knee hyperextension. The presence of equinus foot obstructs the foot clearance and hence the prolonged rectus femoris EMG activity during the swing phase may contribute to shorten the lower limb by flexing the hip. Possible compensatory mechanisms of the proximal muscles of the involved lower limb that can be measured with instrumented gait analysis should be taken into account before the decision for a specific treatment.

Adolescent↗

PubMed2000

Ageing, muscle properties and maximal O(2) uptake rate in humans.

This paper asks how the decline in maximal O(2) uptake rate (VO(2),max) with age is related to the properties of a key muscle group involved in physical activity - the quadriceps muscles. Maximal oxygen consumption on a cycle ergometer was examined in nine adult (mean age 38.8 years) and 39 elderly subjects (mean age 68.8 years) and compared with the oxidative capacity and volume of the quadriceps. VO(2),max declined with age between 25 and 80 years and the increment in oxygen consumption from unloaded cycling to VO(2),max (delta VO(2)) in the elderly was 45 % of the adult value. The cross-sectional areas of the primary muscles involved in cycling - the hamstrings, gluteus maximus and quadriceps - were all lower in the elderly group. The quadriceps volume was reduced in the elderly to 67 % of the adult value. Oxidative capacity per quadriceps volume was reduced to 53 % of the adult value. The product of oxidative capacity and muscle volume - the quadriceps oxidative capacity - was 36 % of the adult value in the elderly. Quadriceps oxidative capacity was linearly correlated with delta VO(2) among the subjects with the slope indicating that the quadriceps represented 36 % of the VO(2) increase during cycling. The decline in quadriceps oxidative capacity with age resulted from reductions in both muscle volume and oxidative capacity per volume in the elderly and appears to be an important determinant of the age-related reduction in delta VO(2) and VO(2),max found in this study.

Adult↗

PubMed1995

Regional muscle loss after short duration spaceflight.

BACKGROUND: Muscle strength and limb girth measurements during Skylab and Apollo missions suggested that loss of muscle mass may occur as a result of spaceflight. Extended duration spaceflight is important for the economical and practical use of space. The loss of muscle mass during spaceflight is a medical concern for long duration flights to the planets or extended stays aboard space stations. Understanding the extent and temporal relationships of muscle loss is important for the development of effective spaceflight countermeasures. HYPOTHESIS: We hypothesized that significant and measurable changes in muscle volume would occur in Shuttle crewmembers following 8 d of weightlessness. METHODS: MRI was used to obtain the muscle volumes of the calf, thigh and lower back before and after the STS-47 Shuttle mission. RESULTS: Statistical analyses demonstrated that the soleus-gastrocnemius (-6.3%), anterior calf (-3.9%), hamstrings (-8.3%), quadriceps (-6.0%) and intrinsic back (-10.3%) muscles were decreased, p < 0.05, compared to baseline, 24 h after landing. At 2 weeks post recovery, the hamstrings and intrinsic lower back muscles were still below baseline, p < 0.05. CONCLUSIONS: These results demonstrate that even short duration spaceflight can result in significant muscle atrophy.

Adult↗

PubMed2005

Effect of high-intensity strength-training on functional measures of balance ability in balance-impaired older adults.

OBJECTIVE: The aim of this study was to evaluate the effect of a 10-week, high-intensity strength-training program targeting key lower extremity muscles for the purpose of improving postural control in balance-impaired older adults. METHODS: A quasi-experimental, delayed entry controlled design was used to evaluate balance ability in balance-impaired older adults after participation in 10 weeks of high-intensity strength training focused on the quadriceps, hamstrings, tibialis anterior, and gastrocnemius muscles. Participants were evaluated using validated clinical measures of functional balance ability: the Berg Balance Scale, the Timed Up and Go, and the Activities-Specific Balance Confidence Scale. RESULTS: After strength training, the exercisers were significantly stronger than the control subjects. They improved significantly on the Berg Balance Scale (P = .030) from a mean score of 48.8 +/- 2.4 of 56 before training to 51.2 +/- 4.3 of 56 after training. The Timed Up and Go (P = .045) and the Activities-Specific Balance Confidence Scale (P = .038) also improved significantly in the experimental group. These changes are associated with a decrease in fall risk. CONCLUSIONS: High-intensity strength training can safely and effectively strengthen lower extremity muscles in balance-impaired older adults, resulting in significant improvements in functional balance ability and decreased fall risk.

Aged↗

PubMed2005

Recruitment of the thigh muscles during sprint cycling by muscle functional magnetic resonance imaging.

The purpose of the present study was to investigate recruitment patterns of the thigh muscles during maximal sprint cycling by muscle functional magnetic resonance imaging (mfMRI). Twelve healthy men participated in this study and performed 2, 5, and 10 sets of 6-s supramaximal cycling with a load of 7.5 % of their body weight with 0.5 min of rest between the sets. Before and immediately after the exercise, T2-weighted MR images, i.e. mfMRI, of the right-thigh were taken to calculate T2 of eleven thigh muscles. Vastus lateralis, semitendinosus, and sartorius were the highest activated, i. e. had the greatest T2 change, among the quadriceps, hamstring, and adductors, respectively, compared with other muscles. Total power output during 2, 5, and 10 sets of sprint cycling was correlated with percent change in T2 in the quadriceps correlated (r (2) = 0.507 to 0.696, p < 0.01), the hamstring (r (2) = 0.162 to 0.335, p < 0.05 approximately 0.001), and the adductor muscles (r (2) = 0.162 to 0.473, p < 0.05 approximately 0.0001). With use of stepwise regression analysis, total power output was significantly correlated with % change in T2 of the vastus medialis (VM) (p < 0.0001) and vastus intermedius (VI) (p < 0.05) (r (2) = 0.698, p < 0.0001). We concluded that eleven thigh muscles were activated non-uniformly, and that the VM and VI play a key role during maximal sprint cycling.

Adult↗

PubMed1995

Motor unit recruitment strategy of knee antagonist muscles in a step-wise, increasing isometric contraction.

The purpose of this study was to determine if differences exist between the control strategies of two antagonist thigh muscles during knee flexion and extension muscular coactivation. Surface myoelectric signal (MES) of the quadriceps (rectus femoris) and the hamstrings (semitendinosus) were obtained from both muscles while performing step-wise increasing contractions during flexion and extension with the knee at 1.57 rad of flexion (90 degrees). The median frequency of the power density spectrum, which is related to the average muscle fiber action potential conduction velocity and therefore to motor unit recruitment, was calculated from each MES. The results suggest that, in all the subjects tested, when the muscle acts as antagonist most motor units are recruited up to 50% of the maximal voluntary force, whereas when the muscle acts as antagonist motor units are recruited up to 40% of the maximal voluntary force. The force range past 40-50% of the maximal force is also characterized by differences between the agonist/antagonist.

Adult↗

PubMed1996

Ontogeny of postural adjustments during sitting in infancy: variation, selection and modulation.

1. The aim of the study was to find out whether the development of postural adjustments occurs via a coupling of simple muscle responses, such as stretch reflexes, or via selection from an innate repertoire of centrally generated response patterns. 2. Postural responses during sitting on a moveable platform were assessed in eleven healthy infants at 5-6, 7-8 and 9-10 months of age. Multiple surface EMGs and kinematics were recorded while the infants were exposed to slow and fast horizontal forward (Fw) and backward (Bw) displacements of the platform. 3. From the youngest testing age onwards, largely variable but direction-specific muscle activation patterns were present. Fw translations resulted predominantly in an activation of the neck flexor, the rectus abdominis and rectus femoris muscle, while the neck-, thoracal- and lumbar extensor muscles (NE, TE, LE) and the hamstrings (Ham) showed varying amounts of inhibition. During Bw translations NE, TE, LE and Ham were preferably activated. The muscle activity could not be explained by simple stretch reflex mechanisms, but is likely to reflect centrally generated motor activity maturing in a predetermined way. However, indications for a contribution of stretch reflex mechanisms were also present. 4. With increasing age the variation in muscle activation patterns decreased, resulting in a selection of the most complete patterns. The ability to modulate the amplitude of the selected, most complete patterns during Fw translations, with respect to platform velocity and initial pelvis position, emerged at 9-10 months.

Afferent Pathways↗

PubMed2005

Neuromuscular biomechanical modeling to understand knee ligament loading.

PURPOSE: This article examines our use of EMG-driven neuromuscular biomechanical models to study how muscles stabilize the knee. EMG can be used to establish which activation patterns are used by people for knee stabilization. However, it does not reveal the effectiveness of these patterns. The EMG-driven models provide quantitative comparisons of the effectiveness of the different knee-stabilizing activation patterns. METHODS: Subjects performed static tasks and common sporting maneuvers that challenged knee joint stability. EMG, joint posture and motion, and external forces and moments were measured during these tasks. These data were used to calibrate the EMG-driven neuromuscular biomechanical model. We then used the model to predict the role of muscles in supporting varus and valgus moments at the knee. RESULTS: We found specific muscle activation patterns to support varus and valgus moments. The most potent activation pattern to stabilize the knee is when the hamstrings or quadriceps are required to generate flexion or extension moments, respectively. The next most effective knee-stabilizing pattern is cocontraction of the hamstring and quadriceps. The small biarticular muscles at the knee provided the least support of varus and valgus moments. In the sporting tasks, sidestepping was found to place the anterior cruciate ligament at high risk of injury. We found that the muscles are the main defense against knee ligament injuries in these tasks. CONCLUSION: Traditional biomechanical and neurophysiological methods have shown that there are specific activation patterns used to stabilize the knee. By also using the EMG-driven neuromuscular biomechanical model, we have shown how effective muscles are in stabilizing the knee. This modeling method provides a new tool to understand knee joint stabilization.

Biomechanical Phenomena↗

PubMed1994

Time-frequency analysis of the surface EMG during maximum height jumps under altered-G conditions.

Surface electromyographic (SEMG) signals are often used to study motor control during human movement. Typically, the SEMG signal is used to determine when the muscle was on or off during the movement. However, determining the time-based frequency content of the SEMG signal in conjunction with the time-history of the movement may provide us with more insight into how the motion is organized. We collected SEMG from 4 muscles, (soleus, vasti, gluteus maximus, hamstrings) while subjects performed jumping and sit-to-stand tasks under altered g-environments. The experiment was performed on the Dynamic Environmental Simulator at Wright Patterson AFB, OH. The subjects performed the tasks at 1.0, 1.2, 1.4, 1.6, and 1.8 g. The SEMG signals were then analyzed using a continuous discrete wavelet transform based on a 4-coefficient Daubechie wavelet. Our initial results show that although the time-history of muscle activation patterns during movements do not always vary significantly at different g levels, the frequency content does change, with more high frequency activation at low g levels, and more low frequency activation at higher g levels. One possible explanation for the difference in frequency activation is fatigue of fast twitch fibers during the experiment. These differences were not apparent from the time-history activation patterns, and are difficult to interpret from standard FFT manipulations.

Electromyography↗

PubMed1992

Co-activation of ipsi- and contralateral muscle groups during contraction of ankle dorsiflexors.

Seventeen adult, healthy subjects, age 38.4 +/- 0.24 years (mean +/- SEM) 7 of which were females, were studied. Each subject was seated on a specially designed chair with trunk and legs fixed and the foot strapped to a rigid plate that was attached to a load cell. The position of the strap was adjusted so as to lie across the foot at the level of the metatarsal bones. The knee and ankle joints were adjusted to 90 degrees. To record EMG activity, pairs of surface electrodes were placed over the belly of both the right and left tibialis anterior, quadriceps, hamstring and contralateral triceps surae muscles. Two experimental paradigms were used, A and B. In A the subject was asked to sustain maximum voluntary contraction (MVC) of the ankle dorsiflexors until the force decreased to 50% of the initial value; in B the subject was asked to carry out contractions of the ankle dorsiflexors for 6 seconds followed by 4 sec relaxation periods. The initial contraction was 20% of MVC followed by 40, 60, 80 and 100% of MVC which represented one cycle. The subject was asked to repeat this cycle 10 times. Voluntary contraction of ankle dorsiflexors was regularly accompanied by activation of other muscles, usually first in the same leg, later in the contralateral leg during MVC of ankle dorsiflexors. When intermittent contractions with step wise increments of force developed by the ankle dorsiflexors were carried out, co-activation of ipsilateral and contralateral muscle groups occurred before the force of the contracting muscles decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2006

Lower extremity muscle morphology in young athletes: an MRI-based analysis.

PURPOSE: This study was conducted to describe lower extremity muscle morphology (volume and peak cross-sectional area (CSA)) in young athletes and compare these with previously reported values. A second aim was to determine if muscle morphological values differ significantly between sides, implying that unilateral measurements cannot represent both limbs accurately. METHODS: Axial spin-echo T1-weighted magnetic resonance (MR) images were obtained between the ankle mortise and iliac crest in 10 athletes (age 18.8 +/- 3.7 yr). Subsequently, each subject's three-dimensional anatomy was digitally reconstructed. Muscle volume, peak CSA, and length were calculated for 13 muscles. RESULTS: The mean volumes and CSA for the current sample of athletes were larger than previously reported values (primarily from cadaver studies of nonathletes). The ratio of total quadriceps volume to total hamstrings volume averaged nearly 3:1 (2.9 +/- 0.2), whereas previous reports have been closer to 2:1 (2.1 +/- 0.2). The relative contribution of each muscle to the muscle group (hamstrings or quadriceps) volume was also different for these athletes. Significant differences in side-to-side muscle morphology were observed in several knee muscles (P < 0.03). Vastus medialis muscle volume was larger in the dominant leg (difference between sides: 59 +/- 25 cm3, representing 15.9 +/- 6.7% of its average volume), whereas vastus lateralis muscle volume was larger in the nondominant leg (difference: 54 +/- 47 cm3 representing 9.6 +/- 8.3% of its average). Despite this, total quadriceps volumes were similar between sides. CONCLUSIONS: Findings suggest that the morphology data presented in this study should be used instead of data from cadavers when studying young athletic people. These data should improve the accuracy of biomechanical modeling in the athletic population.

Adolescent↗

PubMed2005

Perturbation-enhanced neuromuscular training alters muscle activity in female athletes.

Female athletes involved in jumping and cutting sports injure their anterior cruciate ligaments (ACL) 4-6 times more frequently than their male counterparts in comparable sports. Neuromuscular factors, including quadriceps dominance, has been incriminated as contributing to the higher rates of injury in women. Currently, the most effective form of intervention developed to reduce female ACL injury rates has been neuromuscular training. The purpose of this study was to (1) identify gender based muscle activity patterns during disturbed walking that may contribute to ACL injury, and (2) determine if a novel training program could positively influence patterns among healthy female athletes utilizing a disturbed gait paradigm. Twenty healthy athletes (female=10, male=10) were tested. All subjects participated in five trials during which a platform translated horizontally in a lateral direction at heel contact before and after completing ten sessions of a perturbation training program. Electromyographic (EMG) data from the vastus lateralis, medial and lateral hamstrings, and medial gastrocnemius were collected. Trials were analyzed for the muscle onset, termination of activity, peak amplitude, time to peak amplitude, and integrated EMG activity. Muscle cocontraction, the simultaneous activation of antagonistic muscles (lateral hamstrings-vastus lateralis, and medial gastrocnemius-vastus lateralis), was calculated as indicators of active knee stiffness in preparation for heel strike, during weight acceptance and midstance. Prior to training, women had significantly higher peak quadriceps activity and higher integrated quadriceps activity during midstance than men. Both medial and lateral hamstring integrals during midstance increased from pre to posttraining. Onset times to peak activities for hamstrings and quadriceps were similar before training except for medial hamstring time to peak which occurred after heel strike in most women. Time to peak medial hamstring activity moved from after to just before heel strike after training. Women had higher medial gastrocnemius-vastus lateralis cocontraction indices in the preparatory and weight acceptance phases of gait than men after training. Prior to training, the athletic women in our sample demonstrated characteristic quadriceps dominance and decreased active knee stiffness when compared to male athletes. Modulation of activity and timing of ACL agonist musculature (hamstrings and gastrocnemius) from before to after training resulted in normal quadriceps-hamstring balance and increased active stiffness. These alterations in ACL agonist muscle activation patterns may reduce the risk of biomechanical strain injury among a high risk population.

Adult↗

PubMedDate not supplied

Quantitative evaluation of a home exercise program on muscle and functional capacity of patients with osteoarthritis.

Rehabilitation of patients with osteoarthritis of the knees is typically based on home exercise. These programs are believed to benefit patients and have been shown to qualitatively improve strength. The purpose of the present study was to quantify the effects of a 3-mo home exercise program on muscle function and functional capacity. The progressive program included flexibility, strength, endurance, active range of motion and functional activities. Nineteen subjects (67.4 +/- 7.5 yr) with osteoarthritis of the knees began the program, with only nine completing it. The subjects initially had significantly reduced muscle function and functional capacity. Maximal isometric strength of knee extension increased significantly at a knee flexion position of 45 degrees for hip flexion positions of 120 degrees and 60 degrees (35%); however, it failed to increase at longer muscle lengths. There were no significant improvements in hamstring strength. Maximal angular velocity improved after 3 mo of exercise (40%). Muscle endurance did not improve significantly. Although there was a slight increase in functional capacity, these data failed to demonstrate significant clinical or statistical improvement in overall function in patients after home exercise.

Aged↗