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PubMed1997

Thigh muscle size and strength after anterior cruciate ligament reconstruction and rehabilitation.

It is the hypothesis of the senior author (GAA) that high circumference measurements are not an accurate reflection of thigh muscle cross-sectional area or muscle strength after standard rehabilitation following anterior cruciate ligament reconstruction. Likewise, normal quadriceps femoris strength is not achieved in these patients despite aggressive rehabilitation. The purpose of our study was to quantify thigh muscle size and strength and correlate thigh circumference, muscle cross-sectional area by magnetic resonance imaging (MRI), and isokinetic strength in our patients. Thirty-three patients with anterior cruciate ligament repair utilizing autografts of iliotibial band (N = 28), semitendinosus autograft (N = 3), and bone-patellar tendon-bone autograft (N = 2) were retrospectively evaluated 48.7 +/- 6.91 months after surgery. We compared involved operated extremities with uninjured, uninvolved contralateral extremities, measuring thigh circumference, isokinetic peak torque, and cross-sectional area by MRI. We found a significant 1.8% decrease in thigh circumference, a 10% decrease in average quadriceps torque, and a 8.6% decrease in quadriceps cross-sectional area by MRI in the involved extremities compared with the uninvolved extremities. A positive correlation between MRI cross-sectional area, quadriceps, and hamstring peak torque was recorded in involved and uninvolved extremities. A positive correlation between thigh circumference, quadriceps, and hamstring peak torque was found in uninvolved extremities but not in operated extremities. The authors concluded that thigh circumference underestimates atrophy and is not correlated with cross-sectional thigh muscle area by MRI or strength in operated extremities. Persistent quadriceps weakness and decreased cross-sectional area at 49 months postsurgery and rehabilitation continue to challenge our efforts. The pathophysiology of the decrease in thigh muscle size and quadriceps femoris strength is discussed.

Adolescent↗
PubMed1992

[Isokinetic torque of the knee extensor and flexor in patients with recurrent patellar dislocation].

UNLABELLED: In order to establish the role of muscle strength in the recurrent dislocation of the patella, an isokinetic study was performed using BIODEX, by which the concentric (CC) and passive eccentric (PEC) torques of the quadriceps and hamstrings were measured. The angle velocity was set at 30 degrees and 90 degrees/sec. The subjects were divided into three groups: (I) non-surgical, (II) surgical and (III) normal control. In each group 20 knees were tested, and the following results were obtained. 1. Peak torque: At either 30 degrees/sec or 90 degrees/sec of velocity, it was significantly smaller in group I. On the other hand, the torque in group II was similar to that of group III. 2. E/C (eccentric torque/concentric torque) ratio: PEC was divided by CC to express a muscular strength balance. At 30 degrees/sec velocity, group I showed a significantly high E/C ratio. CONCLUSION: The knees with recurrent dislocation of the patella exhibited significantly lower peak torque and irregular curve patterns. The muscle strength, has been restored to a near-normal level in the surgical group, therefore, the muscle weakness in this disorder can be considered to be a secondary factor. The eccentric torque appeared to play a major role in the development of recurrent dislocation of the patella.

Biomechanical Phenomena↗
PubMed1997

Assessment of morbidity of semitendinosus and gracilis tendon harvest for ACL reconstruction.

This study evaluates the morbidity of harvest of both the semitendinosus and gracilis tendons for anterior cruciate ligament reconstruction on nine patients at a minimum of 3 year follow-up. Specifically, the effect on knee function, knee extension and flexion strength, the size of the individual posterior thigh muscles, and the extent of retraction of the semitendinosus and gracilis tendons were evaluated. At final follow-up, each patient was evaluated using the following functional scales: International Knee Documentation Committee (IKDC), Hospital for Special Surgery (HSS), Lysholm, and Tegner. Each patient also had a dynamometer evaluation and a comprehensive magnetic resonance imaging study of both the operated and nonoperated knees. The average functional evaluation scores were: HSS-47.9, Lysholm-88, and Tegner-0.27. The average percent quadriceps and hamstring strength of the operated compared with the nonoperated extremities were 93.7% and 95.3%, respectively; neither decrease was significant. Magnetic resonance imaging evaluation of the cross-sectional areas of the biceps femoris, semimembranosus, and sartorius muscles of both thighs at the same level above the joint were not significantly different. The distal-most insertion of the semitendinosus and gracilis tendons after harvest were always more proximal than the nonoperated side; the average difference was 26.7 mm (range: 11 to 32 mm) for the semitendinosus (unable to calculate in three patients) and 47.1 mm (range: 17 to 72 mm) for the gracilis. We conclude that tendon harvest of the semitendinosus and gracilis muscles does not significantly compromise function and strength despite a more proximal insertion of the retracted tendons. In addition, the majority of cases demonstrated some but never complete regrowth or scar formation of these tendon remnants.

Adult↗
PubMed2005

Kinematic and electromyography analysis of submaximal differences running on a firm surface compared with soft, dry sand.

Kinematic and electromyography (EMG) aspects of running on a firm surface and on soft, dry sand were studied to elucidate mechanisms contributing to the higher energy cost (EC) of sand running. Eight well-trained males (mean VO(2max) 64.3+/-8.6 ml.kg(-1).min(-1)) performed barefoot running trials on a firm surface (wooden floor) and on a soft, dry sand surface (track dimensions 8.8 mx60 cm; depth 13 cm) at 8 and 11 km.h(-1). Kinematic and EMG data were collected simultaneously using an integrated six-camera 50 Hz VICON motion analysis system, an AMTI force-plate and a 10-channel EMG system. Running at 8 km.h(-1) on sand resulted in a greater (P<0.05) stance time (t(s)) compared with the firm surface. At 11 km.h(-1), sand running resulted in a greater stance-to-stride ratio (P<0.005), a shorter stride length (SL) (P<0.05), and a greater cadence (P<0.001) compared with the firm surface values. Hip and knee flexion at initial foot contact (IFC), mid-support (MS) and flexion maximum were greater (P<0.001) running on sand compared with firm surface values at 8 and 11 km.h(-1). Over duration of stride, Hamstring (semimembranosus and biceps femoris) EMG was greater running on sand compared with the firm surface at 8 (P<0.001) and 11 (P<0.05) km.h(-1). During the stance phase in the 8-km.h(-1) trials, EMG in the Hamstrings (P<0.001), Vastii (Vastus lateralis and Vastus Medialis) (P<0.02), Rectus femoris (Rec Fem) (P<0.01) and Tensor Fascia Latae (Tfl) (P<0.0001) were greater than the firm surface measures. During stance in the 11-km.h(-1) trials, Tfl EMG was greater (P<0.02) running on sand compared with the firm surface. At IFC and MS, Hamstrings' EMG was greater on sand at both running speeds (P<0.001). For the Vastii (P<0.02), Rec Fem (P<0.0001) and Tfl (P<0.0001) muscles, the EMG at MS running on sand at both speeds was greater than the firm surface values. The increased EC of running on sand can be attributed in part to the increased EMG activation associated with greater hip and knee range of motion compared with firm surface running.

Adult↗
PubMed1984

Functional treatment of congenital dislocation of the hip.

A prerequisite for the development of congenital dislocation of the hip is ligamentous laxity of the hip-joint, which is demonstrable shortly after birth when the hip can be easily dislocated and reduced. This situation is described as dislocatable hip. Ligamentous laxity naturally tends to disappear, and 90% of all dislocatable hips in fact stabilize spontaneously. No dislocation develops unless an exogenous factor is involved. In infants born in breech presentation the hyperextension of the knees with the resulting increased tension in the hamstrings plays a role. During or shortly after birth, the deflexion of the hip-joint causes an increased tension in the relatively shortened iliopsoas muscle, as a result of which the hip can be dislocated in postero-superior direction. By the time the infant is two months old secondary changes (more specifically restricted abduction) become more pronounced. It may therefore be stated that contracture of the iliopsoas muscle is one of the causes, and restricted abduction a consequence of congenital dislocation of the hip. The degree of dislocation is determined by a balance between the degree of ligamentous laxity and the influence of exogenous factors. When the infant starts to stand and walk, its body weight also begins to function as a deforming exogenous factor. When dislocatable hips are not treated immediately after birth, the frequency of congenital dislocation of the hip at the age of three months amounts to 1-2 per 1000 neonates. The male:female ratio is 1:4. The secondary changes in the osseous structures of the hip-joint should always be studied three-dimensionally. Apart from conventional antero-posterior pelvic roentgenograms, CT-scans can enhance spatial insight. The secondary changes manifest themselves in an enlarged neck-shaft angle, increased femoral anteversion, an increased inclination of the acetabulum and possibly also in diminished acetabular anteversion. In view of the high radiation load involved, examination by CT-scan is not yet a routine procedure in congenital hip dislocation. Radiological examination is usually confined to an antero-posterior pelvic roentgenogram on which the acetabular angle, the neck-shaft angle and the CE-angle can be measured. These are all values projected in a frontal plane. To determine the real values the degree of acetabular and femoral torsion has to be known. With the aid of the CT-scan the torsion of the acetabulum and of the femoral neck as well as their summation - the instability index - can be measured without difficulty.(ABSTRACT TRUNCATED AT 400 WORDS)

Child↗
PubMed1994

Cardiorespiratory fitness and isokinetic muscle strength of elite Asian junior soccer players.

There is a scarcity of descriptive data on the physiological characteristics of elite Asian junior soccer players. The purpose of this study was to evaluate the cardiorespiratory fitness and isokinetic muscle strength of elite junior soccer players in Hong Kong. It was conducted in conjunction with the selection of the Hong Kong team to the 1989 Gothia Cup held in Sweden. Twenty-one top junior soccer players were selected as subjects for the study. The following means (+/- SD) were observed: age 17.3 +/- 1.1 years; height 172.5 +/- 6.2 cm; weight 62.8 +/- 7.0 kg; body fat 5.2 +/- 1.8%; forced vital capacity (FVC) 4.6 +/- 0.6 L; maximum oxygen uptake (VO2max) 58.6 +/- 2.9 ml.kg-1.min-1; anaerobic threshold (AT) 76.7 +/- 10.2% of VO2max; peak isokinetic dominant knee extensor and flexor strengths 3.28 +/- 0.37 Nm.kg-1 and 1.84 +/- 0.24 Nm.kg-1; hamstring to quadriceps peak torque ratio (H/Q) 56 +/- 0.6% measured at 60 degrees s-1. Hong Kong players appeared to have comparable aerobic power, light body weight, poor flexibility and above average isokinetic muscle strength compared to other international junior soccer players. Training programs to improve the contralateral knee muscle imbalance and to increase the fast speed movement capability of the non-dominant knee flexors are recommended.

Adipose Tissue↗
PubMedDate not supplied

Cruciate ligament loading during isometric muscle contractions. A theoretical basis for rehabilitation.

A model of the knee in the sagittal plane was used to investigate the ligament forces resulting when an external load applied to the tibia resisted either extension or flexion of the knee under increasing isometric quadriceps or hamstrings contractions, respectively. An elementary mechanical analysis showed which ligament, the anterior or posterior cruciate, was loaded at a given flexion angle and known line of action of the external load. Ligament force, as a proportion of the external load, was also calculated. The results serve as guidelines for the design of injury-specific physical therapy techniques for use after cruciate ligament reconstruction.

Anterior Cruciate Ligament↗
PubMed2002

The effectiveness of aerobic and muscle strength training in patients receiving hemodialysis and EPO: a randomized controlled trial.

BACKGROUND: Individuals with end-stage renal disease on hemodialysis therapy have reduced aerobic exercise capacity and reduced muscle strength. METHODS: This was a single-blind, randomized, placebo-controlled trial of an exercise intervention in hemodialysis patients administered erythropoietin. The intervention consisted of progressive resisted isotonic quadriceps and hamstrings exercise and training on a cycle ergometer three times weekly for 12 weeks. Individuals in the control group underwent a nonprogressive program of range-of-motion exercises. Both groups were observed for an additional 5 months without intervention. Outcomes were assessed without knowledge of treatment assignment at baseline, 12 weeks, and 5 months. A healthy age- and sex-matched sample provided comparative data. RESULTS: Our sample was relatively high functioning, with a mean score on the Physical Function subscale of the Short Form 36 (SF-36) of 76 of 100. At 12 weeks, there were large and statistically significant differences in favor of the experimental group on the submaximal exercise test (14 W; 95% confidence interval, 2 to 26) and muscle strength (45 lb; 95% confidence interval, 9 to 81), but not in the 6-minute walk, symptoms questionnaire, or SF-36. Differences between the intervention and control groups at 12 weeks were not evident on retesting 5 months after the end of the intervention. Compared with the healthy sample, patients were significantly lower functioning on the submaximal exercise test, muscle strength, and 6-minute walk test at baseline. CONCLUSION: In this high-functioning sample, the exercise program improved physical impairment measures, but had no effect on symptoms or health-related quality of life. The impact on patients with a greater degree of physical dysfunction needs to be rigorously studied.

Anemia↗
PubMed1995

Bone mass, muscle strength, and different body constitutional parameters in adolescent boys with a low or moderate exercise level.

This study was conducted to evaluate the association between muscle strength of the thigh, different body constitutional parameters, and bone mineral density (BMD) in adolescents. The subjects were 26 healthy adolescent boys, age 15.9 +/- 0.3 years, not training for more than 3 h per week. BMD was measured in total body, head, humerus, spine, femur, and tibia/fibula. Univariate correlations were measured between the explanatory parameters height, weight, body mass index (BMI), fat mass, lean body mass, quadriceps strength, hamstrings strength, and each BMD site using Pearson's coefficient of correlation. The explanatory variables were also used in a multivariate analysis to explain each BMD site. There was a high degree of concordance when comparing the two methods of analysis. Using the multivariate analysis, quadriceps strength and lean body mass showed significant independent correlations to all BMD sites measured, the correlations being stronger for the adjacent femur and tibia/fibula than for the distant humerus and head. Hamstrings strength correlated significantly and independently with tibia/fibula BMD and spine BMD. Fat mass, BMI, and weight correlated significantly and independently to all BMD sites except femur. This study demonstrates a general relationship between BMD and different body constitutional parameters and muscle strength of the thigh.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed2004

Muscle force redistributes segmental power for body progression during walking.

The ankle plantar flexors were previously shown to support the body in single-leg stance to ensure its forward progression [J. Biomech. 34 (2001) 1387]. The uni- (SOL) and biarticular (GAS) plantar flexors accelerated the trunk and leg forward, respectively, with each opposing the effect of the other. Around mid-stance their net effect on the trunk and the leg was negligible, consistent with the body acting as an inverted pendulum. In late stance, their net effect was to accelerate the leg and trunk forward, consistent with an active push-off. Because other muscles are active in the beginning and end of stance, we hypothesized that their active concentric and eccentric force generation also supports the body and redistributes segmental power to enable body forward progression. Muscle-actuated forward dynamical simulations that emulated observed walking kinematics and kinetics of young adult subjects were analyzed to quantify muscle contributions to the vertical and horizontal ground reaction force, and to the acceleration and mechanical power of the leg and trunk. The eccentric uniarticular knee extensors (vasti, VAS) and concentric uniarticular hip extensors (gluteus maximus, GMAX) were found to provide critical support to the body in the beginning of stance, before the plantar flexors became active. VAS also decelerated the forward motion of both the trunk and the leg. Afterwards when VAS shortens in mid-stance, it delivered the power produced to accelerate the trunk and also redistributed segmental power to the trunk by continuing to decelerate the leg. When present, rectus femoris (RF) activity in the beginning of stance had a minimal effect. But in late stance the lengthening RF accelerated the knee and hip into extension, which opposed swing initiation. Though RF was lengthening, it still accelerated the trunk forward by decelerating the leg and redistributing the leg segmental power to the trunk, as SOL does though it is shortening instead of lengthening. Force developed from highly stretched passive hip structures and active force produced by the uniarticular hip flexors assisted GAS in swing initiation. Hamstrings (HAM) decelerated the leg in late swing while lengthening and accelerated the leg in the beginning of stance while shortening. We conclude that the uniarticular knee and hip extensor muscles are critical to body support in the beginning of stance and redistribution of segmental power by muscles throughout the gait cycle is critical to forward progression of the trunk and legs.

Computer Simulation↗
PubMed2000

Joint angular velocity in spastic gait and the influence of muscle-tendon lengthening.

BACKGROUND: Joint angular velocity (the rate of flexion and extension of a joint) is related to the dynamics of muscle activation and force generation during walking. Therefore, the goal of this research was to examine the joint angular velocity in normal and spastic gait and changes resulting from muscle-tendon lengthening (recession and tenotomy) in patients who have spastic cerebral palsy. METHODS: The gait patterns of forty patients who had been diagnosed with spastic cerebral palsy (mean age, 8.3 years; range, 3.7 to 14.8 years) and of seventy-three age-matched, normally developing subjects were evaluated with three-dimensional motion analysis and electromyography. The patients who had cerebral palsy were evaluated before muscle-tendon lengthening and nine months after treatment. RESULTS: The gait patterns of the patients who had cerebral palsy were characterized by increased flexion of the knee in the stance phase, premature plantar flexion of the ankle, and reduced joint angular velocities compared with the patterns of the normally developing subjects. Even though muscle-tendon lengthening altered sagittal joint angles in gait, the joint angular velocities were generally unchanged at the hip and knee. Only the ankle demonstrated modified angular velocities, including reduced dorsiflexion velocity at foot-strike and improved dorsiflexion velocity through mid-stance, after treatment. Electromyographic changes included reduced amplitude of the gastrocnemius-soleus during the loading phase and decreased knee coactivity (the ratio of quadriceps and hamstring activation) at toe-off. Principal component analyses showed that, compared with joint-angle data, joint angular velocity was better able to discriminate between the gait patterns of the normal and cerebral palsy groups. CONCLUSIONS: This study showed that muscle-tendon lengthening corrects biomechanical alignment as reflected by changes in sagittal joint angles. However, joint angular velocity and electromyographic data suggest that the underlying neural input remains largely unchanged at the hip and knee. Conversely, electromyographic changes and changes in velocity in the ankle indicate that the activation pattern of the gastrocnemius-soleus complex in response to stretch was altered by recession of the complex.

Adolescent↗
PubMed1993

Isokinetic quadriceps training in patients with patellofemoral pain syndrome.

The aims of the present investigation were (a) to evaluate the effect of eccentric quadriceps training in patients with unilateral patellofemoral pain and (b) to compare the effect of eccentric and concentric quadriceps training in patients with bilateral patellofemoral pain. Fifteen patients (9 male and 6 female, aged 17-36 years with a mean of 27.5 years) participated in this study. Nine patients had unilateral pain and trained their painful leg eccentrically, while six had bilateral pain and trained one leg eccentrically and the other concentrically. Quadriceps muscle training was performed on a Kin-Com dynamometer at 90 degrees/s and 120 degrees/s angular velocity twice a week for 8 weeks. Before and after the treatment period the thigh muscle torques were measured on the Kin-Com dynamometer at 60 degrees/s, 90 degrees/s, 120 degrees/s and 180 degrees/s for quadriceps and at 60 degrees/s and 180 degrees/s for hamstrings. Nine controls, matched for gender and age with the group with unilateral pain, were tested in the same way on the Kin-Com dynamometer. For functional evaluation a knee score was calculated before training, after 8 weeks of training and at a mean of 3.4 years after completion of the training. After 8 weeks of training and at follow-up times of 1 and 3.4 years the patients were also questioned regarding whether or not they felt improvement from the training programme. To determine the degree of knee pain during the training Borg's pain scale was used. The results showed that, compared with the controls, the patients had a significantly lower knee extensor torque in their painful leg at all velocities measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1998

Quadriceps atrophy after partial resection of the patellar tendon: an experimental study in a rat model.

Quadriceps muscle atrophy of rats was examined after resection of the central third (group 1) or the lateral two thirds (group 2) of the patellar tendon, the tensor fascia lata (group 3), or the medial hamstring (group 4). The quadriceps atrophied in groups 1 and 2, and more so in group 2, but there was no atrophy in groups 3 or 4. Thus, after an anterior cruciate ligament reconstruction procedure using the patellar tendon, resection of the patellar tendon itself leads to quadriceps atrophy and the extent of atrophy is related to the resected width.

Animals↗
PubMed1999

Continuous versus separate isokinetic test protocol: the effect of estradiol on the reproducibility of concentric and eccentric isokinetic measurements in knee muscles.

OBJECTIVE: To investigate the effects of estradiol on the reliability of concentric and eccentric isokinetic measurements of knee muscles and to compare the reproducibility of measurements in a continuous test protocol and a separate test protocol. DESIGN: Repeated measurements. SETTING: A university exercise physiology laboratory. PARTICIPANTS: Twenty healthy sedentary women volunteers, aged 19 to 37 years, who had regular menstrual cycles (ranging from 27 to 35 days). Subjects were randomly divided into two groups: continuous test group (n = 10) and separate test group (n = 10) and tested at the menstrual phase (days 1 to 3) and preovulatory phase (days 12 to 14) in both legs. METHODS: Continuous reciprocal flexion-extension contractions were used in the continuous test group, and separated flexion and extension contractions were used in the separate test group. Four different test protocols were designed to determine the effects of test mode and number of contractions on the isokinetic measurements: Group A, 4 reciprocal flexion-extension repetitions at each angular velocity of 60 degrees/sec and 180 degrees/sec in one leg in the continuous test group; Group B, 4 and 20 reciprocal flexion-extension repetitions at 60 degrees/sec and 180 degrees/sec, respectively, in the contralateral leg in the same group; Group C, 4 repetitions in extensors and flexors at each angular velocity of 60 degrees/sec and 180 degrees/sec with a 5-minute rest between the two muscle groups in one leg in the separate test group; and Group D, 4 repetitions at 60 degrees/sec and 20 repetitions at 180 degrees/sec for extensors and flexors with a 5-minute rest between the two muscle groups in the contralateral leg in the same group. Blood samples were analyzed for sex hormones, creatine kinase, and lactate dehydrogenase before the tests at the menstrual phase and the preovulatory phase. In addition subjective assessment of muscle soreness was made at each blood sampling. RESULTS: Concentric and eccentric peak torque, average power, total work, and endurance ratio at both angular velocities were not significantly different in the two phases of the cycle by paired observation t test for each of the four groups. Except for concentric and eccentric endurance ratios of quadriceps and hamstrings, and concentric peak torque and average power of hamstrings at 180 degrees/sec in Group D, intraclass correlation coefficients of tested variables showed correlations that were moderate to excellent (p < .05) between two phases. In addition, there were no significant correlations between estradiol and the tested variables. Resting serum creatine kinase and lactate dehydrogenase activities and the score of muscle soreness were at the baseline and not significantly different prior to the tests performed at preovulatory and menstrual phases. CONCLUSIONS: The results suggest that: (1) reproducibility of isokinetic tests during the menstrual cycle is not influenced by sex hormone fluctuations, particularly estradiol; (2) when compared with the separate test protocol used in this study, the continuous test protocol is more appropriate to measure peak torque, average power, total work, and endurance ratio for both muscle groups of the knee even if the number of contractions is changed. However, these conclusions are specific to sedentary individuals; to make more valid conclusions, further studies with different subject groups are needed.

Adult↗