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PubMed2005

Epidemiology of injuries in English professional rugby union: part 2 training Injuries.

OBJECTIVES: To undertake a detailed epidemiological study of training injuries sustained by professional rugby union players in order to define their incidence, nature, severity, and causes. METHODS: A two season prospective design was used to study training injuries associated with 502 rugby union players at 11 English Premiership clubs. Team clinicians reported all training injuries on a weekly basis and provided details of the location, diagnosis, severity, and mechanism of each injury. Training exposures for individual players were recorded on a weekly basis. Loss of time from training and match play was used as the definition of an injury. RESULTS: The overall incidence of injury was 2.0 per 1000 player-hours, and each injury resulted on average in 24 days lost time. Recurrences, which accounted for 19% of injuries, were more severe (35 days) than new injuries (21 days). Twenty two per cent of all training occurred during the preseason but 34% of all injuries were sustained in this period. Hamstring, calf, hip flexor/quadriceps, and adductor muscle injuries were the most common for backs, whereas hamstring, lateral ankle ligament, and lumbar disc/nerve root injuries predominated for forwards. Lumbar disc/nerve root, shoulder dislocation/instability, and hamstring muscle injuries for forwards and hamstring muscle and anterior cruciate ligament injuries for backs caused the greatest number of days absence. Running was the predominant cause of injury for both forwards and backs, although the overall incidence and severity of injuries sustained during skills training were significantly greater than those sustained during conditioning training. CONCLUSIONS: On average, a club will have 5% of their players unavailable for selection as a consequence of training injuries.

Adult↗

PubMed2000

Dynamic control and conventional strength ratios of the quadriceps and hamstrings in subjects with anterior cruciate ligament deficiency.

The hamstrings:quadriceps muscle strength ratio has been used as an indicator of normal balance between the knee flexors and extensors. A more functional approach to this strength ratio would be to compare opposite muscle actions of antagonistic muscle groups. The dynamic strength control ratio (DSCR) should give a more appropriate measure relating to knee function. There is a lack of normative data relating to DSCR for anterior cruciate ligament (ACL) deficient subjects. Effects of ACL deficiency on isokinetic peak torque for eccentric and concentric muscle actions of the quadriceps and hamstrings, in conjunction with isometric peak torque, were examined in 10 patients awaiting reconstructive surgery (male = 8, female = 2 ; age = 32.8 +/- 8.3 years; height = 1.77 +/- 0.08 m; mass = 72.1 +/- 12.5 kg). These variables were assessed using an isokinetic dynamometer. The results were considered in terms of the conventional ratio and DSCR. Anterior tibial drawer was measured using a knee ligament arthrometer to confirm clinical diagnosis of ACL rupture. The isokinetic peak torque data analysed were for angular velocities of 1.05 rad s(-1) (60 degrees s(-1)). Significant strength deficits were apparent between normal and injured sides for: concentric isokinetic quadriceps action (p < 0.05); isometric quadriceps action at 70 degrees of knee flexion (p < 0.05); isometric quadriceps action at 40 degrees of knee flexion (p<0.01); eccentric isokinetic hamstrings action (p < 0.05). With bilateral comparison, the conventional strength ratios showed no significant difference, as did the DSCR. The bilateral comparison of isometric strength ratios revealed significant losses in quadriceps strength for the injured side (p < 0.05) but no significant losses in hamstring strength (p > 0.05). Thus, differences can be seen in conventional ratios and DSCR for ACL-deficient subjects. This is an area of clinical interest with the increasing frequency of ACL reconstruction using hamstrings tendons.

Adult↗

PubMed1996

Subacute encephalomyelitis presenting as stiff-person syndrome: clinical, polygraphic, and pathologic correlations.

A 60-year-old woman presented with stiff-person syndrome (SPS). Treatment with diazepam controlled her painful spasms initially. Two and one-half years after the onset of SPS, new spells of paroxysmal leg jerking and apnea developed. A spell was recorded with simultaneous video and polygraphic techniques that revealed simultaneous firing of motor unit potentials in several muscles (paraspinal, internal hamstring, and abdominal muscles). Apnea was associated with arterial oxygen desaturation. An increase in the dose of diazepam decreased the number and severity of these episodes. Seventeen months later, the patient began to taper the diazepam dose. Shortly thereafter, she had a cardiorespiratory arrest and subsequently died. Autopsy showed small chronic inflammatory foci in the pancreas (some associated with islets) and findings of diffuse encephalomyelitis characterized by perivascular cuffing in the spinal cord, brainstem, thalamus, hippocampus, and amygdala and a dense mononuclear infiltrate in the anterior horns of the lumbar and cervical cord, with relative preservation of axons and myelin. Cell typing showed this infiltrate was polyclonal and reactive. There have been rare cases of SPS associated with encephalomyelitis reported previously. Although the prolonged course in our patient suggested that SPS may have preceded encephalomyelitis, the more likely explanation is that the patient had an unusually long course of encephalomyelitis alone.

Brain↗

PubMed1998

Effect of fatigue on hamstring coactivation during isokinetic knee extensions.

We examined the effect of fatigue of the quadriceps muscles on coactivation of the hamstring muscles and determined if the response is different between two isokinetic speeds in ten males and ten females with no history of knee pathology. Electromyographic data were recorded from the vastus lateralis and biceps femoris muscles during 50 maximal knee extensions at isokinetic speeds of 1.75 rad x s(-1) (100 degrees x s(-1)) and 4.36 rad x s(-1) (250 degrees x s(-1)). A greater degree of coactivation was apparent at the higher speed, but the increase in coactivation of the hamstring muscles was similar at both speeds. The results revealed that: (1) coactivation is greater at a higher isokinetic speed, and (2) coactivation increases during fatigue, but the rate of increase is independent of contraction velocity.

Adult↗

PubMed1986

Importance of correcting isokinetic peak torque for the effect of gravity when calculating knee flexor to extensor muscle ratios.

The purpose of our investigation was to compare, for the hamstring and quadriceps femoris muscles, peak torque values uncorrected for gravity with the peak torque values corrected for gravity and to determine the effect of making this correction on the hamstring to quadriceps femoris muscle peak torque ratio at slow and fast isokinetic speeds. We measured peak torques isokinetically at 60 degrees/sec (slow) and 240 degrees/sec (fast) in 25 female university soccer players. The gravity effect torque (GET) is the torque resulting from the effect of gravity on the combined weight of the leg and dynamometer arm at the precise angle of extension and flexion peak torque. The GET was added to the measured quadriceps femoris muscle peak torque and subtracted from the hamstring muscle peak torque to yield gravity corrected values. Failure to consider GET greatly underestimated quadriceps femoris muscle torque and overestimated hamstring muscle torque and the ratio between these torques at both speeds. Whereas the uncorrected hamstring to quadriceps femoris muscle peak torque ratio increased as speeds went from 60 degrees/sec to 240 degrees/sec, the gravity corrected ratio significantly decreased. Clinicians must remember the importance of making the gravity correction in patients with reduced torque output where the gravitational torque is a greater percentage of the measured torque to ascertain correctly the relative strength of antagonists inversely affected by gravity.

Adolescent↗

PubMed2002

Relationship between wire EMG activity, muscle length, and torque of the hamstrings.

OBJECTIVE: To determine the effect of change of muscle length on the torque and wire electromyographic activity of six knee flexor muscles. DESIGN: Maximum isometric knee flexion torque and wire EMG data were collected at nine different positions. BACKGROUND: In vivo EMG-length-tension relationship is difficult to determine because of the interaction between muscle length and moment arm. The study of two-joint muscles allows the change of muscle length at one joint while preserving stable mechanical relationships at the other. This model facilitates understanding of length-tension and EMG-length relationship in vivo. METHODS: Nineteen subjects performed maximum isometric knee flexion contraction at nine positions of varying hip and knee angles. Wire EMG activity was recorded from semitendionsus, semimembranosus, long and short head of the biceps femoris, gracilis and sartorious muscles. RESULTS: As the two-joint hamstrings were lengthened, torque was significantly increased. Maximum isometric torque ranged from 257 to 716 kg cm. The ratio of the torque values to EMG activity of all muscles was increased at longer muscle lengths. A change in the muscle length of the two-joint hamstrings did not produce a consistent change of EMG activity. The short head of the biceps femoris and sartorius muscles increased their activity as the angle of knee flexion increased. CONCLUSIONS: Maximum torque of knee flexion occurs at the most lengthened position of the hamstrings. EMG activity did not consistently change with the change in muscle length. RELEVANCE: Understanding in vivo length-tension relationship and associated EMG activity is important for designing rehabilitation protocols, tendon lengthening and transfer and interpretation of EMG data.

Adult↗

PubMed1994

Stretching exercises: effect on passive extensibility and stiffness in short hamstrings of healthy subjects.

Passive muscle stretch tests are common practice in physical therapy and rehabilitation medicine. However, the effects of stretching exercises are not well known. With an instrumental straight-leg-raising set-up the extensibility, stiffness, and electromyographic activity of the hamstring muscles have been experimentally determined and the effects of stretching exercises have been evaluated. Fourteen volunteers, aged 20 to 38 years (mean 27.3) were selected from a young healthy population with the toe-touch test (finger-ground distance greater than 0cm), and a straight-leg-raising angle about 80 degrees. According to usual standards the diagnosis was short hamstrings. One group of seven subjects was treated during 4 weeks with a daily home exercise program aimed at stretching the hamstrings, whereas the untreated group was used as a control. Instrumental straight-leg-raising was performed in the subjects of both groups. The significance of the differences between the mean values was determined with the Student's t-test. Comparison of the data obtained before and after the muscle stretching program showed a slight but significant increase in the extensibility of the hamstrings accompanied with a significant increase of the stretching moment tolerated by the passive hamstring muscles. However, the elasticity remained the same. It is concluded that stretching exercises do not make short hamstrings any longer or less stiff, but only influence the stretch tolerance.

Adult↗

PubMed1998

Isokinetic strength testing does not predict hamstring injury in Australian Rules footballers.

OBJECTIVE: To determine the relation of hamstring and quadriceps muscle strength and imbalance to hamstring injury using a prospective observational cohort study METHOD: A total of 102 senior male Australian Rules footballers aged 22.2 (3.6) years were tested at the start of a football season. Maximum voluntary concentric and eccentric torque of the hamstring and quadriceps muscles of both legs was assessed using a Kin-Com isokinetic dynamometer at angular velocities of 60 and 180 degrees/second. Twelve (11.8%) players sustained clinically diagnosed hamstring strains which caused them to miss one or more matches over the ensuing season. RESULTS: There were no significant differences for any of the isokinetic variables comparing the injured and non-injured legs in players with unilateral hamstring strains (n=9). Neither the injured nor the non-injured leg of injured players differed from the mean of left and right legs in non-injured players for any isokinetic variable. The hamstring to opposite hamstring ratios also did not differ between injured and non-injured players. A hamstring to opposite hamstring ratio of less than 0.90 and a hamstring to quadriceps ratio of less than 0.60 were not associated with an increased risk of hamstring injury. A significantly greater percentage of players who sustained a hamstring strain reported a history of hamstring strain compared with non-injured players (p=0.02). However, this was not related to muscle weakness or imbalance. CONCLUSIONS: Isokinetic muscle strength testing was not able to directly discriminate Australian Rules football players at risk for a hamstring injury.

Adult↗

PubMed2002

Effects of aquatic resistance training on neuromuscular performance in healthy women.

PURPOSE: The purpose of this study was to investigate the effects of a progressive 10-wk aquatic resistance training on neuromuscular performance and muscle mass of the knee extensors and flexors in healthy women. METHODS: Twenty-four healthy women (34.2 +/- 3.9 yr) were randomly assigned into aquatic exercise (N = 12) and control group (N = 12). Maximum knee extension and flexion torques were measured isometrically and at constant angular velocities of 60 degrees x s(-1) and 180 degrees x s(-1) (isokinetic) with simultaneous electromyography (EMG) recordings of the quadriceps and hamstrings. The lean muscle mass (LCSA) of the quadriceps and hamstring muscles was determined by computed tomography scanning. RESULTS: Significant interaction of group by time was observed in each of the measured parameters. The change in extension and flexion isometric/isokinetic torque varied between 8 and 13% and in EMGs between 10 and 27% in the exercise group. The change in the quadriceps LCSA of the exercise group was 4% and in hamstrings 5.5%. CONCLUSIONS: The results of the present study showed that 10 wk of progressive aquatic resistance training resulted in significant improvement in muscle torque of the knee extensors and flexors accompanied with proportional improvement in neural activation and with significant increase in the LCSA of the trained muscles. Aquatic training can be recommended for neuromuscular conditioning in healthy persons.

Adult↗

PubMed1989

Postural synergies in axial movements: short and long-term adaptation.

Fast backward trunk movements are accompanied by hip, knee and ankle rotation which compensate for the backward shift of the center of gravity. The electromyographic pattern associated with the performance of these movements and the associated synergies consists of a fairly synchronous activation of the prime mover (erectores spinae) and the muscles situated at the back of the leg (hamstring, calf muscles). This pattern is called the "non anticipated pattern". The effect of training on the EMG pattern and on the subjects' mechanical performances was investigated by comparing a population of untrained subjects with one of highly trained gymnasts. A new EMG pattern was observed in the highly trained gymnasts, the "distally anticipated pattern" consisting of an early activation of the gastrocnemius, and in some subjects also of the hamstring, indicating that a long term adaptation had taken place. Performances expressed as a ratio between the displacement of the center of gravity projection onto the ground and the velocity of the movement were clearly better in the gymnasts. Short term adaptation was found to occur in the gymnasts and not in the untrained group when the movement was performed while standing on a narrow support. A suppression of the distal gastrocnemius burst occurred in the gymnasts from the first trial under the constrained standing condition whereas no change occurred in the untrained group. The flexibility of the EMG patterns associated with axial movements occurring either spontaneously or as a result of long or short term training is discussed.

Adaptation, Physiological↗

PubMedDate not supplied

The influence of muscle forces and external loads on cruciate ligament strain.

We know it is important to avoid excessive strain on reconstructed ligaments, but we do not know how individual muscles affect cruciate ligament strain. To answer this, we studied the effect of muscle forces and external loads on cruciate ligament strain. Nine cadaveric knee joints were tested in an apparatus that allowed unconstrained knee joint motion. Quadriceps, hamstring, and gastrocnemius muscle forces were simulated. Additionally, external loads were applied such as varus-internal or valgus-external rotation forces. Cruciate ligament strain was recorded at different knee flexion angles. Activation of the gastrocnemius muscle significantly (P < 0.05) strained the posterior cruciate ligament at flexion angles larger than 40 degrees. Quadriceps muscle activation significantly strained the anterior cruciate ligament when the knee was flexed 20 degrees to 60 degrees (P < 0.01) and reduced the strain on the posterior cruciate ligament in the same flexion range (P < 0.05). Activation of the hamstring muscles strained the posterior cruciate ligament when the knee was flexed 70 degrees to 110 degrees (P < 0.05). Combined varus and internal rotation forces significantly increased anterior cruciate ligament strain throughout the flexion range (P < 0.05). The results suggest that to minimize strain on the ligament after posterior cruciate ligament surgery, strong gastrocnemius muscle contractions should be avoided beyond 30 degrees of knee flexion. The study also calls into question the use of vigorous quadriceps exercises in the range of 20 degrees to 60 degrees of knee flexion after anterior cruciate ligament reconstruction.

Adult↗

PubMed1993

Lower extremity muscular flexibility in long distance runners.

Muscle tightness is often considered to be a predisposing factor in muscle injuries. The purpose of this study was to assess the muscle flexibility of the hamstrings, rectus femoris, iliopsoas, gastrocnemius, and soleus muscles in long distance runners. Range of motion measurements of five movements, including hip flexion with knee extended, hip extension with knee flexed, hip extension with knee extended, ankle dorsiflexion with knee extended, and ankle dorsiflexion with knee flexed, were evaluated to determine muscle tightness. Twenty runners and 20 nonrunners volunteered for the study. Each group consisted of 10 males and 10 females. The observed means were compared between runners and nonrunners, males and females, plus the dominant and nondominant leg using a three-way analysis of variance. The runners were found to have tighter hamstrings (p < .05), and soleus (p < .05) muscles than nonrunners. There was no significant difference in rectus femoris and iliopsoas muscle tightness in runners compared with nonrunners. In addition, the males had tighter hamstring muscles than the females in both runners and nonrunners (p < .05). The hamstring muscles of the dominant leg were tighter than the hamstrings of the nondominant leg in all subjects (p < .05). In conclusion, long distance runners appear to have posterior muscle tightness in the lower extremity.

Adolescent↗

PubMedDate not supplied

Interrelationships of strength and gait before and after hamstrings lengthening.

Muscle-tendon lengthenings are an essential part of the orthopaedic management of static and dynamic joint contractures associated with cerebral palsy. Although these procedures typically have a positive biomechanical effect on joint alignment, the potential negative effects of alterations in tendon length on muscle strength and gait function have not been well documented in these patients, in whom muscle weakness is a prevalent clinical symptom. The purpose of this study was to examine the change in strength values of the hamstring and quadriceps muscle groups during a 9-month postoperative period in patients who had undergone hamstring tendon lengthenings, in comparison to an operative "no hamstring surgery" control group, and to relate baseline strength and postoperative changes to gait function in these patients. Results for the "hamstring surgery" group indicated that although hamstring strength declined initially, the strength increased with time and was similar to preoperative values by 9 months. Quadriceps strength measured at 30 degrees of knee flexion increased significantly during the recovery period as a direct result of improvements in knee extension. Although hamstring surgery produced an immediate effect on passive motion and knee-joint alignment, functional improvement, as evidenced by increased stride length, was not evident until strength values approximated or exceeded preoperative values.

Adolescent↗

PubMed1971

Recurrent inhibition of fusimotor neurones exhibiting background discharges in the decerebrate and the spinal cat.

1. Discharges of functionally single fusimotor neurones have been recorded from the nerves to hamstring and triceps surae muscles in the cat. Background discharges were examined for both muscle groups in decerebrate animals but only for hamstrings in spinal preparations.2. Background discharges in forty-six out of sixty-seven triceps and twenty-one out of twenty-five flexor hamstring fusimotor neurones were inhibited by an antidromic volley in other efferent axons. One semimembranosus neurone was similarly inhibited.3. The inhibition was due to impulses in alpha motoneurone axons. It had a mean central delay of 2.3 +/- 0.2 msec and 2.7 +/- 0.2 msec for triceps and hamstring muscles respectively and was detectable for up to 100 msec, although shorter durations of the order of 10 msec were common.4. It was possible for a fusimotor neurone in one ventral root to be inhibited by an antidromic volley in an adjacent ventral root. The origin of the inhibition was not confined to a unit's own muscle nerve.5. The actions of eserine and strychnine on the inhibition were similar to their effects on recurrent inhibition of alpha motoneurones. Eserine potentiated and strychnine reduced the inhibition following an antidromic volley.6. The inhibition was found in spinal and in decerebrate cats but it was depressed following spinal section. L-Dopa in the spinal animal depressed the background discharge of some neurones and potentiated that of others. Both sets of neurones could be inhibited by antidromic volleys.7. It is concluded that antidromic inhibition of some fusimotor neurones does occur and that it is highly likely to be mediated via recurrent collaterals and Renshaw interneurones. The evidence from the use of L-Dopa indicates that the inhibition is present to both dynamic and static fusimotor neurones.

Animals↗

PubMed1990

[Pindolol-induced rhabdomyolysis in sarcoid myopathy].

A 72-year-old man suddenly developed severe muscle weakness following the treatment with pindolol (Calvisken) for three days. Neurological examination on admission disclosed marked proximal muscle weakness with absent deep tendon reflexes. Laboratory data showed significant increase of serum CK, aldolase and myoglobin. Electromyography revealed both neurogenic and myogenic changes in all muscle tested. Skeletal muscle CT showed patchy low density areas in muscles of thigh and leg, especially in the hamstrings. Femoral muscle biopsy demonstrated a granulomatous nodule with multinucleated giant cells in the degenerated muscle fibers showing small-grouped atrophy. By Mb-PAP staining, Mb-negative fibers were randomly distributed among normally stained ones. Leu 1, 3a, 4, HLA-DR positive cells were found adjacent to the granuloma by immunoperoxidase staining. After immediate withdrawal of pindolol and treatment with steroid, he recovered muscle strength and enzyme activities were normalized in a week. Beta blockers have been known to induce muscle cramps or pain and moderate elevation of serum muscle enzymes. However, severe muscle weakness with highly elevated enzyme activities leading to rhabdomyolysis as noticed in the present case was rarely reported in the literature. Underlying sarcoid myopathy might be suspected to exaggerate this unusual case of pindolol-induced rhabdomyolysis. A careful use of pindolol is emphasized.

Aged↗

PubMed2005

Do the hamstrings operate at increased muscle-tendon lengths and velocities after surgical lengthening?

Children with crouch gait frequently walk with improved knee extension during the terminal swing and stance phases following hamstrings lengthening surgery; however, the mechanisms responsible for these improvements are unclear. This study tested the hypothesis that surgical lengthening enables the hamstrings of persons with cerebral palsy to operate at longer muscle-tendon lengths or lengthen at faster muscle-tendon velocities during walking. Sixty-nine subjects who had improved knee extension after surgery were retrospectively examined. The muscle-tendon lengths and velocities of the subjects' semimembranosus muscles were estimated by combining kinematic data from gait analysis with a three-dimensional computer model of the lower extremity. Log-linear analyses confirmed that the subjects who walked with abnormally short muscle-tendon lengths and/or slow muscle-tendon velocities preoperatively tended to walk with longer lengths (21 of 29 subjects, p<0.01) or faster velocities (30 of 40 subjects, p<0.01) postoperatively. In these cases, surgical lengthening may have slackened the subjects' tight hamstrings and/or diminished the hamstrings' spastic response to stretch. Other subjects walked with muscle-tendon lengths and velocities that were neither shorter nor slower than normal preoperatively (22 of 69 subjects), and the semimembranosus muscles of most of these subjects did not operate at increased lengths or velocities after surgery; in these cases, the subjects' postsurgical improvements in knee extension may have been unrelated to the hamstrings surgery. Analyses of muscle-tendon lengths and velocities may help to distinguish individuals who have "short" or "spastic" hamstrings from those who do not, and thus may augment conventional methods used to describe patients' neuromusculoskeletal impairments and gait abnormalities.

Adolescent↗

PubMed2007

Early versus late start of open kinetic chain quadriceps exercises after ACL reconstruction with patellar tendon or hamstring grafts: a prospective randomized outcome study.

The purpose of the present investigation was to evaluate physical outcome after anterior cruciate ligament (ACL) reconstruction with early versus late initiation of open kinetic chain (OKC) exercises for the quadriceps in patients operated on either patellar tendon or hamstring grafts. Sixty-eight patients, 36 males and 32 females, with either patellar tendon graft (34 patients) or hamstring graft (34 patients) were enrolled in this study. All patients were randomly allocated to either early (the 4th postoperative week) or late (the 12th postoperative week) start of OKC exercises for the quadriceps, resulting in four subgroups: patellar tendon reconstruction, early start (P4) or late start (P12) of OKC quadriceps exercises, hamstring tendon reconstruction, early start (H4) or late start (H12) of quadriceps OKC exercises. Prior to surgery and 3, 5 and 7 months later, assessments of range of motion (goniometer), anterior knee laxity (KT-1000), postural sway (KAT 2000), thigh muscle torques (Kin-Com dynamometer) and anterior knee pain (anterior knee pain score) were evaluated. No significant group differences were found in terms of range of motion 3, 5 and 7 months postoperatively. The H4 group showed a significantly higher mean difference of laxity over time of 1.0 mm (CI: 0.18-1.86) than the P4 group (P=0.04). Within the same type of surgery, the H4 against the H12, the mean difference over time was 1.2 mm (0.37-2.1) higher in the H4 group than in the H12 group (P=0.01). There were no significant group differences in terms of postural sway or anterior knee pain at the different test occasions. Significant differences in trends (changes over time) were found when comparing the four groups, for both quadriceps muscle torques (P<0.001) and hamstring muscle torques (P<0.001). All groups, except the P4 group, reached preoperative values of quadriceps muscle torques at the 7 months follow-up. In the H4 and the H12 groups, significantly lower hamstring muscle torques at the 7 months follow-up compared with preoperative values were found. In conclusion, early start of OKC quadriceps exercises after hamstring ACL reconstruction resulted in significantly increased anterior knee laxity in comparison with both late start and with early and late start after bone-patellar tendon-bone ACL reconstruction. Furthermore, the early introduction of OKC exercises for quadriceps did not influence quadriceps muscle torques neither in patients operated on patellar tendon nor hamstring tendon grafts. On the contrary, it appears as if the choice of graft affected the strength of the specific muscle more than the type of exercises performed. Our results could not determine the appropriate time for starting OKC quadriceps exercises for patients who have undergone ACL reconstruction with hamstring tendon graft. Future studies of long-term results of anterior knee laxity and functional outcome are needed.

Adult↗

PubMed2003

Recovery of standing balance and functional mobility after stroke.

OBJECTIVE: To examine the extent to which recovery of functional balance and mobility is accompanied by change in a few specific physiologic measures of postural control. DESIGN: Longitudinal prospective study. SETTING: Laboratory setting in Ontario. PARTICIPANTS: Twenty-seven volunteers (age, 64.2+/-13.7y) undergoing 4 weeks of rehabilitation after stroke participated. At initial testing, patients were 32.7+/-18.4 days poststroke and exhibited a moderate level of motor recovery (lower-extremity and postural control, stages 3-4 on the Chedoke-McMaster Stroke Assessment Impairment Inventory). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Three functional measures (Berg Balance Scale, Clinical Outcome Variables Scale, gait speed) were assessed. Three physiologic measures (electromyographic data of hamstrings and soleus muscles bilaterally, postural sway, arm acceleration) were taken while subjects stood quietly on a force platform and while they performed a rapid shoulder flexion movement of the nonparetic upper extremity. RESULTS: After 1 month of rehabilitation, there was an overall significant improvement in all outcome measures (functional, physiologic). However, 10 patients failed to show any improvement in the electromyographic activation of hamstrings muscle on the paretic side in response to the rapid arm movement. These patients compensated by increasing the anticipatory activation of the nonparetic hamstrings. CONCLUSION: After stroke, patients showed improvement in both physiologic and functional measures of balance and mobility over a 1-month period. We have identified some patients who may be using compensatory strategies to increase function. The factors that may predict those patients who are likely to use compensatory strategies awaits further study.

Aged↗