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PubMed1984

Changes in popliteal angle measurement in infants up to one year of age.

The purpose of this study was to determine trends in the changes of the popliteal angle in 130 normal infants between one day and 12 months of age, for use in assessing infants with possible neuromuscular pathology. Using a 360 degree goniometer, the popliteal angle was measured with the hip held at 90 degree flexion, to indicate hamstring-muscle tightness. Limitation of knee extension was also measured with the hip extended (HEKE angle) to indicate capsular tightness. Both the popliteal and HEKE angle measurements showed greatest limitation of knee extension at birth, which decreased until eight months of age, when most infants showed no limitation. A highly significant negative correlation was found between age and mean popliteal and HEKE angles.

Anthropometry↗

PubMed1957

A comparison of the local effects of various intramuscular injections in the rat.

A method is described for the assessment of the local reaction produced by intramuscular injections. This method involves the histological examinations of the injection site after injection of material into the hamstring muscles of the rat. The results obtained with both aqueous and oily materials are described; the correlation of these results with clinical observations in man is discussed.

Animals↗

PubMed1982

Some pharmacological studies on the spastic mouse.

1 Full-wave rectification and integration of the EMG signal recorded from the hamstring muscles of the spastic mouse was used to evaluate the actions of a variety of drugs on the muscle rigidity of these mutants, animals in which no histological lesion has yet been found. 2 Profound and long-lasting muscle relaxant responses were consistently observed upon the injection of diazepam (2 mg/kg, i.p.) and flunitrazepam (2 mg/kg, i.p.). Such responses were always greater than those obtained upon injection of 40% (v/v) propylene glycol (10 ml/kg) alone, the vehicle for the benzodiazepines. 3 The muscle relaxant action of a low dose (0.25 mg/kg i.p.) of the benzodiazepine Roll-6896 was not shared by the same dose of its enantiomer Roll-6893. 4 Profound and long-lasting muscle relaxation was caused by sodium valproate (696 mg/kg, i.p.). Consistent muscle relaxant responses were also observed upon the injection of pentobarbitone (30 mg/kg, i.p.), but not phenobarbitone (30 mg/kg, i.p.). 5 Other drugs that had little or no detectable effect on the muscle rigidity of the spastic mouse included diphenylhydantoin (30 mg/kg, i.p.) and bromocriptine (10 mg/kg, s.c.) while, in some animals, benztropine (2 mg/kg, i.p.) and baclofen (10 mg/kg, i.p.) increased muscle rigidity. 6 The development of full muscle relaxant responses to flunitrazepam (2 mg/kg, i.p.) and to sodium valproate (696 mg/kg, i.p.) was shown to depend upon mild warming of the animals with radiant heat, a procedure which can increase muscle spindle afferent input to the spinal cord. 7 The results suggest a hyperactivity of stretch reflexes in the spastic mouse, ameliorated selectively by those drugs that enhance the GABA-mediated presynaptic inhibition of such pathways.

Animals↗

PubMed1992

Intrathecal neurokinin A facilitates the spinal nociceptive flexor reflex evoked by thermal and mechanical stimuli and synergistically interacts with substance P.

The neuropeptide neurokinin A was injected intrathecally and its effect on the spinal nociceptive flexor reflex was examined. The reflex, which was evoked by electrical, thermal or mechanical stimulation of the foot and was recorded from the ipsilateral hamstring muscles, was substantially facilitated by 7 pmol intrathecally injected neurokinin A. The facilitatory effect of neurokinin A to thermal stimulation was, however, significantly stronger than to electrical or mechanical stimuli. Furthermore, co-administration of neurokinin A with substance P induced a significant synergistic facilitation of the reflex. It is suggested that neurokinin A, like substance P, may be released in association with activation of polymodal C-nociceptors.

Animals↗

PubMed1982

The role of spinal cord transmission in the ventilatory response to electrically induced exercise in the anaesthetized dog.

1. The ventilatory response to electrically induced ;exercise' was studied in six chloralose-anaesthetized dogs. The on-transient and steady-state responses to ;exercise' were compared in the same dogs before and after spinal cord transection at T8/9 (dermatome level T6/7) on fifteen occasions.2. Phasic hind limb ;exercise' was induced for periods of 4 min by passing current (2 Hz modulated 50 Hz sine wave) between two needles inserted through the hamstring muscles. The maximum current used was 30 mA. This was below the level previously found to produce an artifactual stimulation of breathing with the cord intact.3. Cord transection produced no significant change in either the resting values of ventilation ( V(I)) and CO(2) production ( V(CO) (2)) or the ventilatory equivalent for CO(2) during ;exercise' ( big up tri, open V(I)/ big up tri, open V(CO) (2)).4. During the steady state of exercise P(a, CO) (2) was on average significantly lower than at rest with the cord intact (mean big up tri, openP(a, CO) (2), - 2.1 mmHg; range - 5.7 to + 1), and higher, though not significantly, with the cord cut (mean P(a, CO) (2), + 1.2 mmHg; range - 1.5 to + 4.3). However, even in the absence of spinal cord transmission, the ventilatory response to exercise could not be accounted for on the basis of CO(2) sensitivity; the big up tri, open V(I)/ big up tri, openP(a,CO) (2) obtained with exercise (apparent sensitivity) was significantly greater than that obtained with CO(2) inhalation (true sensitivity) both before and after cord section.5. V(I) and V(CO) (2) increased more slowly with the cord cut than with the cord intact. This was thought to be due to a slower increase in venous return in the absence of sympathetic innervation of the lower half of the body following cord transection.6. Similar experiments were performed during muscle paralysis (following gallamine triethiodide). Ventilation was maintained with a respirator controlled by phrenic nerve activity. These experiments showed an increase in ventilation, independent of muscle contraction, which was only present when the cord was intact and which was confined to the on-transient. Only in the absence of spinal cord transmission could there be certainty that the dynamics of the ventilatory response to electrically induced ;exercise' was free of artifact.7. It was concluded that spinal cord transmission is not necessary for the steady-state ventilatory response to electrically induced exercise of the hind limbs.8. The dog with spinal cord transection provides a suitable model for the study of the chemical control of breathing during electrically induced exercise.

Anesthesia, General↗

PubMed1984

Is the voluntary control of exercise in man necessary for the ventilatory response?

The ventilatory response to electrically induced exercise (EEL) was studied in eighteen normal subjects and compared with the response to performing the same exercise voluntarily (EV). EEL was produced by surface electrode stimulation of the quadriceps and hamstring muscles so as to cause a pushing movement at 1 HZ against a spring load; this produced no pain or discomfort. Matching of EV to EEL was achieved by subjects copying a tension signal recorded during EEL and displayed on a storage oscilloscope. There were no differences between the resting states measured before either form of exercise. The ventilatory response (change in ventilation as a ratio of the change in CO2 elimination) was similar in the two types of exercise. The increases in ventilation and CO2 elimination were greater with EEL. Small but significant increases in the gas exchange ratio and serum lactate were found for EEL but not for EV, suggesting an increase in anaerobic metabolism in EEL. End-tidal PCO2 showed little change in either form of exercise. In some runs end-tidal PCO2 rose, but insufficiently to account for the ventilatory response as judged by the response to inhaled CO2. In two subjects arterial blood samples showed small and inconsistent changes in both Pa,CO2 and PaO2 for EV and EEL. pH and base excess changes also were consistent with more anaerobiosis with EEL compared to EV. The first ten breaths of exercise were used to study the on transient. In EV, expiratory duration shortened and ventilation increased significantly on the first breath but CO2 elimination did not increase until the second breath; in EEL, these variables did not change significantly until the second breath. For the remainder of the on transient the pattern of the ventilatory response was similar for EV and EEL. By the end of the on transient both EV and EEL had reached approximately 80% of their final steady-state values. These results suggest that a normal ventilatory response can occur in the absence of a drive to exercise from the cortex.

Adult↗

PubMed1984

The role of spinal cord transmission in the ventilatory response to exercise in man.

The ventilatory response to electrically induced exercise was studied in thirteen patients with traumatic spinal cord transection at or about the level of T6. The steady-state and on-transient responses to this exercise were compared with those obtained in eighteen normal subjects (Adams, Garlick, Guz, Murphy & Semple, 1984). Exercise was produced by surface electrode stimulation of the quadriceps and hamstring muscles so as to produce a pushing movement at 1 HZ against a spring load. At rest there was no significant difference between normals and patients, except that the patients had a lower CO2 elimination (VCO2) and end-tidal PCO2 (PET,CO2) and a higher heart rate. On exercise the mean rise in VCO2 for the patients was 172 ml min-1 (S.D. 72), and for the normals was 287 ml min-1 (S.D. 143). The corresponding mean changes in ventilation (VI) were 4.4 l min-1 (S.D. 2.2) and 7.6 l min-1 (S.D. 3.2). However, the ventilatory equivalent for CO2 (delta VI/delta VCO2) in the steady state was not significantly different between patients (26.0, S.D. 5.9) and normals (28.5, S.D. 7.4). In the steady state there was a mean rise in PET,CO2 of 0.9 mmHg (S.D. 1.4) in the normals, and 3.2 mmHg (S.D. 2.7) in the patients, but there was overlap between the two groups. In many experimental runs in both groups, PET,CO2 did not rise, and sometimes fell. Where PCO2 did rise, the ventilatory response to exercise could not be accounted for on the basis of the ventilatory sensitivity to CO2 inhalation. From arterial sampling in three of the patients it was found that when PET,CO2 rose, the corresponding change in Pa,CO2 was less. During the on transient, there was a significant rise in both VCO2 and VI by the second breath in both groups. At the end of the on transient the normal subjects had achieved 84% (S.D. 40) of the steady-state increase in VCO2 and 88% (S.D. 24) of the increase in VI. The corresponding values for the patients were 67% (S.D. 17) and 77% (S.D. 16) respectively; these differences between normals and patients are significant. The increase of VI during the on transient in the patients was achieved almost entirely by an increase in tidal volume whereas in normals, an increase in respiratory rate was a more important component. We conclude therefore that in man, spinal cord transection with a presumed loss of muscle afferents allows a ventilatory response to electrically induced exercise that cannot be explained by classical chemoreception.(ABSTRACT TRUNCATED AT 400 WORDS)

Carbon Dioxide↗

PubMed1987

The early circulatory and ventilatory response to voluntary and electrically induced exercise in man.

1. The ventilatory and circulatory responses to electrically induced leg exercise (EEL) were studied in seven normal subjects and compared with the responses to performing the same exercise voluntarily (EV). 2. EEL was produced by surface electrode stimulation of the quadriceps and hamstring muscle groups. This produced a push-relax pattern of exercise against a spring load and was free of any pain or discomfort. EV, at the same level, was achieved by subjects copying a display of timing and force information on a storage oscilloscope. 3. Cardiac output was estimated using validated Doppler ultrasound measurements of the velocity in the ascending aorta, combined with an estimate of aortic cross-sectional area using M-mode echocardiography. 4. Data from EV and EEL exercise runs were matched, within subjects, for the increase in oxygen consumption during the first 30 s of exercise; there were no significant differences between the resting states prior to either form of exercise. 5. The first ten beats of exercise were used to study the circulatory on-transient. The cardiac output responses to both EV and EEL were similar; however, in EV alone there was an initial significant drop in stroke volume and a slightly greater rise in heart rate. 6. The first five breaths of the response were used to study the ventilatory on-transient, and by measuring cardiac output, stroke volume and heart rate throughout each breath, the relationship between circulatory and ventilatory variables could be assessed. Ventilation showed a significantly greater rise at the onset of exercise during EV than during EEL; PET,CO2 (end-tidal CO2 pressure) showed small but significant falls for both EV and EEL. 7. The circulatory changes on a breath-by-breath basis are similar for EV and EEL although the ventilatory changes differ. In both EV and EEL the average increase in ventilation at the onset of exercise is proportionally greater than the average increases in cardiac output. Individual exercise runs show no particular relationship between circulatory and ventilatory change. 8. The results provide no support in man during mild leg exercise for a 'cardiodynamic' drive to breathing.

Adult↗

PubMed2006

Spontaneous complete hamstring avulsion causing posterior thigh compartment syndrome.

Complete avulsion of the hamstring muscle group from its ischial origin is an uncommon condition, and has been mostly reported in young athletes. A case is presented in which a middle aged man sustained this injury and developed a compartment syndrome of the thigh, which has not been previously reported. The surgical management of this patient is described.

Compartment Syndromes↗

PubMed2001

A randomised clinical trial of the efficacy of drop squats or leg extension/leg curl exercises to treat clinically diagnosed jumper's knee in athletes: pilot study.

OBJECTIVES: To compare the therapeutic effect of two different exercise protocols in athletes with jumper's knee. METHODS: Randomised clinical trial comparing a 12 week programme of either drop squat exercises or leg extension/leg curl exercises. Measurement was performed at baseline and after six and 12 weeks. Primary outcome measures were pain (visual analogue scale 1-10) and return to sport. Secondary outcome measures included quadriceps and hamstring moment of force using a Cybex II isokinetic dynamometer at 30 degrees/second. Differences in pain response between the drop squat and leg extension/curl treatment groups were assessed by 2 (group) x 3 (time) analysis of variance. Two by two contingency tables were used to test differences in rates of return to sport. Analysis of variance (2 (injured versus non-injured leg) x 2 (group) x 3 (time)) was also used to determine differences for secondary outcome measures. RESULTS: Over the 12 week intervention, pain diminished by 2.3 points (36%) in the leg extension/curl group and 3.2 points (57%) in the squat group. There was a significant main effect of both exercise protocols on pain (p<0.01) with no interaction effect. Nine of 10 subjects in the drop squat group returned to sporting activity by 12 weeks, but five of those subjects still had low level pain. Six of nine of the leg extension/curl group returned to sporting activity by 12 weeks and four patients had low level pain. There was no significant difference between groups in numbers returning to sporting activity. There were no differences in the change in quadriceps or hamstring muscle moment of force between groups. CONCLUSIONS: Progressive drop squats and leg extension/curl exercises can reduce the pain of jumper's knee in a 12 week period and permit a high proportion of patients to return to sport. Not all patients, however, return to sport by that time.

Adolescent↗

PubMed1977

C0-contraction and stretch reflexes in spasticity during treatment with baclofen.

Surface electromyograms were recorded from the quadriceps and hamstring muscles of 11 spastic patients during cyclical flexion and extension movements of the knee. A potentiometer strapped to the knee recorded the angle of the joint, the output signal being displayed on an oscilloscope. The patient used this signal to track a sine wave target for 20 cycles. The observer then moved the patient's limb through a further 20 cycles tracking the same target. Recordings were repeated at intervals for four hours after an oral dose of baclofen. Analysis of the recordings showed that the response of a spastic muscle to lengthening is not the same during passive movement as during voluntary movement. In mild spasticity stretch reflexes appear to be suppressed by voluntary effort whereas in severe spasticity they are enhanced. Baclofen suppressed the response to passive stretch by over 30% at plasma concentrations of over 250 ng/ml and by 50% at concentrations of over 400 ng/ml, but this effect was largely extinguised during voluntary movement.

Adolescent↗

PubMed1976

Synchronization of respiratory frequency by somatic afferent stimulation.

In cats anesthetized with chloralose-urethan, vagotomized, paralyzed, and artifically ventilated, superficial radial (cutaneous) and hamstring (muscle) nerve afferents were stimulated while phrenic nerve electrical activity was recorded. The results obtained with both types of nerves were similar. Stimulation in mid and late expiration advanced the onset of the next inspiration, shortening its duration. Stimulation in early inspiration advanced, while that in late inspiration delayed, the onset of the next expiration. These effects were often accompanied by changes in phrenic motoneuron firing patterns (earlier recruitment, increased discharge frequency, increased slope of integrated phrenic neurogram). Repetitive somatic afferent stimulation produced sustained increases in respiratory frequency in all cats and in half of them entrainment of respiratory frequency to the frequency of stimulation occurred at ratios such as 4:3, 4:5, 1:2, 1:3, 1:4, and 1:7. The lowest stimulus intensity required for evoking these phase shifts was between 5 and 10T (threshold of most excitable fibers) for muscle afferents and between 1 and 2T for cutaneous afferents. These results demonstrate the existence of a reflex mechanism capable of locking respiratory frequency to that of a periodic somatic afferent input. They also provide an experimental basis for the hypothesis that reflexes are resposible for the observed locking between step or pedal frequency and respiratory rate during exercise in man.

Animals↗

PubMed1995

Bipedal reflex coordination to tactile stimulation of the sural nerve during human running.

1. Cutaneous reflex responses were elicited during human running (8 km/h) on a treadmill by electrical stimulation of the sural nerve at the ankle. Stimulus trains (5 pulses of 1 ms at 200 Hz) at three nonnociceptive intensities, which were 1.5, 2.0, and 2.5 times perception threshold (PT), were delivered at 16 phases of the step cycle. For 11 subjects the surface electromyographic (EMG) activity of both the ipsilateral and contralateral long head of the biceps femoris (iBF and cBF, respectively), the semitendinosus (iST and cST), the rectus femoris (iRF and cRF), and the tibialis anterior (iTA and cTA) were recorded. 2. During human running nonnociceptive sural nerve stimulation appears to be sufficient to elicit large, widespread and statistically significant reflex responses, with a latency of approximately 80 ms and a duration of approximately 30 ms. These reflex responses seem to be an elementary property of human locomotion. This is indicated by the occurrence of the responses in all subjects, the consistency of most of the reflex patterns across the subjects and, apart from a small amount of habituation, the reproducibility of the responses during the course of the experiment. 3. The responses are modulated continuously throughout the step cycle such that their magnitude does not in general covary with the background locomotor activities. This is observed most clearly in iST, iTA, and cTA for which statistically significant reflex reversals are demonstrated, and in cRF and cTA for which the responses are gated during most of the step cycle. 4. The response magnitude generally increases as a function of increasing intensity, whereas the phase-dependent reflex modulation is intensity independent. 5. A functional dissociation within the ipsilateral hamstring muscles is demonstrated: the iBF and iST show an antagonistic reflex pattern (facilitatory and suppressive, respectively) during the periods of synergistic background locomotor activity in the step cycle. Contralaterally, however, the cBF and cST are reflexively activated as close synergists during these periods. 6. The reflex responses and their phase-dependent modulation are different for the homologous muscles in the two legs. Yet, some similarities are observed. These are present rather with respect to the phase of the corresponding leg than with respect to the phase of the stimulated leg. Both observations suggest that the phase-dependent reflex modulation is controlled separately in the ipsilateral and contralateral legs. 7. The response simultaneity in all investigated muscles supports the notion of a coordinated cutaneous interlimb reflex during human running.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1988

Involuntary movements of the lower extremity following dorsal root entry zone lesions in a man treated for phantom limb pain.

A patient developed continuous patterned involuntary movements of abduction-adduction, flexion-extension of his right lower extremity following surgical placement of spinal dorsal root entry zone lesions for the treatment of phantom limb pain. The stereotype movements were monitored by video and electromyographic recording of quadriceps femoris and hamstring muscles. Administration of para-chlorophenylbutyric acid (baclofen) dramatically stopped the involuntary movements and electromyographic silence ensued. Voluntary muscle movements were preserved. The theoretical implications of this unique movement disorder and central patterning of motor activity within the spinal cord are discussed.

Baclofen↗

PubMed1994

Neuromuscular control of lifting in the elderly.

The aim of this investigation was to determine, utilising an electromyographic (EMG) technique, the influence of the ageing process on the neuromotor control of the stoop-lift. Seven elderly (60-75 years) and seven young (18-25 years) subjects completed a series of ten unresisted (no weight) stoop-lifts. EMG potentials were recorded with 4-mm bipolar surface electrodes from the erector spinae and medial hamstring muscle groups. The temporal features of the stoop-lift itself were recorded with an electrogoniometer. The results of this investigation showed that the elderly subjects had a significantly (p < 0.05) earlier onset of the erector spinae muscle during the up-phase of the stoop-lift compared to the younger subjects. In addition, reactivation of the erector spinae muscle in the up-phase occurred at hand positions significantly (p < 0.05) closer to the floor in the elderly group indicating more stooped postures. Thus the EMG profiles of the erector spinae within the elderly subjects performing unresisted stoop-lifts approximated those previously reported in younger subjects performing resisted (with a weight) lifting. The earlier onset of the erector spinae in the up-phase of the stoop-lift was partially explained by a significant (p < 0.05) reduction in flexibility (sit and reach test) associated with the elderly subjects. The results further stress the potential for injury associated with the utilisation of the stoop-lift, particularly by elderly populations.

Adolescent↗

PubMedDate not supplied

Dynamic function after anterior cruciate ligament reconstruction with autologous patellar tendon.

The purpose of this study was to dynamically assess the functional outcome of patients who had undergone successful anterior cruciate ligament reconstruction using an autologous patellar tendon technique and to determine whether their dynamic knee function was related to quadriceps and hamstring muscle strength. The knee kinematics and kinetics of 22 subjects who had undergone anterior cruciate ligament reconstruction (mean age, 27 +/- 11 years) and of 22 age- and sex-matched healthy control subjects were determined during various dynamic activities using a computerized motion analysis and force plate system. The differences in the sagittal plane angles and external moments between the two groups during light (walking), moderate (climbing and descending stairs), and higher-demand (jogging, jog and cut, jog and stop) activities were related to isokinetic strength measurements. Although patients who are asymptomatic and functioning well after anterior cruciate ligament reconstruction can perform normally in light activities, higher-demand activities reveal persistent functional adaptations that require further study.

Adolescent↗

PubMedDate not supplied

Codominance of the individual posterior cruciate ligament bundles. An analysis of bundle lengths and orientation.

BACKGROUND: It is unclear how each bundle of the posterior cruciate ligament contributes to posterior knee stability. HYPOTHESIS: Changes in bundle orientation and length occur such that neither bundle dominates in restraining posterior tibial motion throughout knee flexion and extension. STUDY DESIGN: Controlled laboratory study. METHODS: Six fresh-frozen cadaveric knees were studied in a joint-testing rig with individual quadriceps and hamstring muscle loading. Kinematic data for the tibia and femur were obtained at knee flexion angles from 0 degrees to 120 degrees. The joint was then disarticulated, and the insertions of the two bundles on the tibia and femur were digitized. RESULTS: Length of the anterolateral bundle increased with increasing knee flexion angle from 10 degrees to 120 degrees. Length of the posteromedial bundle decreased with increasing knee flexion angle from 0 degrees to 45 degrees and increased slightly from 60 degrees to 120 degrees. Length of the anteromedial bundle was significantly less than that of the posteromedial at 0 degrees, 10 degrees, and 20 degrees of knee flexion. The anterolateral bundle was significantly more horizontal at flexion angles of 0 degrees, 10 degrees, 20 degrees, 30 degrees, and 45 degrees (P < 0.05). The posteromedial bundle was more horizontal at 120 degrees. CONCLUSIONS: Changes in orientation take place such that neither bundle dominates in restraining posterior tibial motion throughout knee flexion and extension. CLINICAL RELEVANCE: Double-bundle reconstructions achieve more physiologic knee function.

Aged↗

PubMedDate not supplied

The hamstring syndrome. A new diagnosis of gluteal sciatic pain.

A series of 59 patients was treated and operated on for pain felt over the area of the ischial tuberosity and radiating down the back of the thigh. This condition was labeled as the "hamstring syndrome." Pain was typically incurred by assuming a sitting position, stretching the affected posterior thigh, and running fast. The patients usually had a history of recurrent hamstring "tears." Their symptoms were caused by the tight, tendinous structures of the lateral insertion area of the hamstring muscles to the ischial tuberosity. Upon division of these structures, complete relief was obtained in 52 of the 59 patients.

Adolescent↗