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PubMed2006

[Consequences of pain on isokinetic performance after anterior cruciate ligament reconstruction using a semitendinosus and gracilis autograft].

PURPOSE OF THE STUDY: The purpose of this study was to investigate isokinetic performance of the knee twelve months after ligamentoplasty of the anterior cruciate ligament using four-strand hamstring autografts. We wanted to ascertain the effect of exercise-induced postoperative pain. MATERIAL AND METHODS: Between January 2001 and January 2003, at total of 75 patients underwent arthroscopic hamstring ligamentoplasty performed by the same surgeon. Isokinetic measurements were obtained at 4, 6, and 12 months postoperatively. At four months, four subpopulations were identified depending on the presence or not of exercise-induced pain. RESULTS: Fifty-two patients were pain free, seven presented exercise-induced posterior pain, nine exercise-induced anterior pain and seven diffuse pain with more than 5 degrees limitation of extension and 10 degrees for flexion. Isokinetic measurements at an angular speed of 60 degrees /s performed at the fourth postoperative month were compared with the pain-free population and demonstrated a significant flexion deficit in patients with exercise induced posterior pain (32% vs 18%, p = 0.04), significant extension deficit in patients with exercise-induced anterior pain (45% vs 30%, p = 0.02), and significant deficit in extension (58% vs 30%, p = 0.001) and flexion (39% vs 18%, p = 0.01) in patients with diffuse pain and limited joint motion. Certain deficits persisted one year after surgery. Patients did not achieve their prior level in contact pivot sports if they presented exercise-induced anterior pain. The population with diffuse pain and limited joint motion only resumed line sports. DISCUSSION: It is not easy to ascertain the origin of knee pain after ligamentoplasty. Posterior pain at the harvesting site occurs after hamstring reconstruction (defective regeneration or incomplete disinsertion with muscle retraction). The hamstring technique can also lead to anterior pain involving all the structures of the extension system. Diffuse pain with limited joint motion is related to "minor" reflex dystrophy. CONCLUSION: A mean 10% extensor and flexor isokinetic deficit can be expected one year after four-strand hamstring ligamentoplasty. Isokinetic tests performed four months postoperatively in patients with exercise-induced pain can provide objective evidence of difficult recovery. Posterior exercise-induced pain is associated with a flexion deficit of more than 30%. Anterior pain with exercise is associated with 45% deficit in extension. Diffuse pain with limited joint motion is associated with more than 40% in flexion and more than 55% in extension. These quantitative results enable the surgeon to inform the patient concerning potential sports level after repair since recovery will be longer with greater deficit.

Adult↗

PubMed1973

Electromyographic study of the rigidospasticity of athetosis.

The static and dynamic components of the tonic stretch reflex and shortening reactions have been studied in 10 patients with athetosis. EMG activity could be recorded only from the biceps muscle when the patient was at rest. The dynamic stretch reflex increased with the velocity of stretching in all muscles examined except the biceps. The biceps stretch reflex was found to be inhibited by increasing muscle length, whereas the stretch reflexes of triceps, hamstrings, and quadriceps muscles were facilitated by increasing muscle length. Reinforcement increased resting activity in the biceps and the dynamic shortening reaction of the triceps muscle. Both these effects were suppressed by the action of phenoxybenzamine. Although phenoxybenzamine was shown to reduce muscle tone in a double-blind controlled trial, no corresponding improvement was detected in involuntary movements or the patients' performance in a tracking test. The differences between the pattern of hypertonus in athetosis, Parkinson's disease, spasticity, and activated normal subjects are presented in discussion.

Adult↗

PubMed1992

[A case of distal myopathy with rimmed vacuole formation, progresses into proximal-dominant muscle involvement].

A case of 55-year-old male with distal myopathy with rimmed vacuole formation is reported. He first noticed dragging of his legs at the age of forty-three. Two years later, he was evaluated to have muscle wasting and weakness in lower legs. In another ten years, he became unable to stand or walk unaided. On physical examination, proximal limb muscles were more severely affected than distal limb muscles. Notably, muscle strength of the quadriceps femoris muscles were weak (MRC Scale 3/5), compared to hamstrings, tibialis anterior muscle and gastrocnemius muscle (4/5). Serum creatine kinase, electromyography, nerve conduction velocities were all compatible with this diagnosis. A computed tomography of the musculoskeletal system was consistent with physical findings. Muscle biopsy revealed many fibers with typical rimmed vacuoles (approximately 6% of fibers). Additionally, small amount of ragged-red fibers (0.5%) was noted. Histochemical reaction showed a focal deficiency of cytochrome c oxidase. This case suggests that during the longstanding course of the illness, proximal limb muscles may be more severely affected, and quadriceps femoris muscle may be predominantly involved.

Cytochrome-c Oxidase Deficiency↗

PubMed2000

Effects of a three-month therapeutic exercise programme on flexibility in subjects with low back pain.

BACKGROUND AND PURPOSE: Spinal and muscle flexibility have been studied intensively and used clinically as outcome measurements in the rehabilitation of subjects with low back pain. The results of previous studies are contradictory and there is a lack of longitudinal data on the effects of long term therapeutic exercise on flexibility. METHOD: A controlled experimental study was conducted to determine the effects of progressive therapeutic exercise on spinal and muscle flexibility. Eighty-six chronic low back pain subjects fulfilled the inclusion criteria and were divided into three study groups: (1) intensive training group, (2) home exercise group and (3) control group. The intervention period lasted three months and measurements were performed at both the beginning of the study and immediately after intervention. Follow-up measurements were carried out six and 12 months after baseline. Spinal flexibility was measured with lumbar flexion, extension, spinal lateral flexion and rotation, and muscle flexibility was measured with measurements of erector spinae, hamstring and iliopsoas muscles. Also self-reported outcomes of the Oswestry Index and Borg Scale--Back Pain Intensity were used. Associations between change (pre- to post-treatment) were determined for the dependent variables. RESULTS: The results showed no correlation between flexibility, the Oswestry Index or back pain intensity. After the first three-month period lumbar flexion, extension and spinal rotation decreased among all subjects. Spinal rotation and erector spinae muscle flexibility improved significantly with intensive training. At the nine-month follow-up, erector spine flexibility was still greater than at baseline. Hamstring flexibility increased among the intensive training and home exercise groups from pre- to post-intervention. However, the degree of hamstring flexibility gained during training was subsequently lost following the period without programmed exercise in both training groups. Self-reported outcome variables showed positive changes among the three study groups after the completion of intervention period, but these changes were only able to be maintained during subsequent follow-ups for the intensive training and home exercise groups. CONCLUSIONS: The findings suggest that flexibility does not play an important role in coping with chronic low back pain for subjects whose functional limitations are not severe. Also, it appears that the achieved gains in spinal and muscle flexibility may not be able to be maintained without continued exercise.

Case-Control Studies↗

PubMed1993

Can muscle co-contraction protect knee ligaments after injury or repair?

A computer-based model of the knee was used to study forces in the cruciate ligaments induced by co-contraction of the extensor and flexor muscles, in the absence of external loads. Ligament forces are required whenever the components of the muscle forces parallel to the tibial plateau do not balance. When the extending effect of quadriceps exactly balances the flexing effect of hamstrings, the horizontal components of the two muscle forces also balance only at the critical flexion angle of 22 degrees. The calculations show that co-contraction of the quadriceps and hamstring muscles loads the anterior cruciate ligament from full extension to 22 degrees of flexion and loads the posterior cruciate at higher flexion angles. In these two regions of flexion, the forward pull of the patellar tendon on the tibia is, respectively, greater than or less than the backward pull of hamstrings. Simultaneous quadriceps and gastrocnemius contraction loads the anterior cruciate over the entire flexion range. Simultaneous contraction of all three muscle groups can unload the cruciate ligaments entirely at flexion angles above 22 degrees. These results may help the design of rational regimes of rehabilitation after ligament injury or repair.

Anterior Cruciate Ligament↗

PubMed1995

Caudal medullary pathways to lumbosacral motoneuronal cell groups in the cat: evidence for direct projections possibly representing the final common pathway for lordosis.

The nucleus retroambiguus (NRA) projects to distinct brainstem and cervical and thoracic cord motoneuronal cell groups. The present paper describes NRA projections to distinct motoneuronal cell groups in the lumbar enlargement. Lumbosacral injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) were made to localize and quantify the retrogradely labeled neurons in the caudal medullary lateral tegmentum. These injections were combined with spinal hemisections to distinguish between neurons having ipsi-or contralaterally descending axons. The NRA-lumbosacral fibers descend almost exclusively contralaterally, but neurons in areas surrounding the NRA project mainly ipsilaterally. In an anterograde tracing study, injections of WGA-HRP or tritiated leucine were made in the region of the NRA to determine the NRA targets in the lumbosarcral cord. Hemisections in C2 made it possible to distinguish between NRA projections and projections from neurons in the adjoining lateral tegmentum. The results show delicate NRA projections to distinct lumbosacral motoneuronal cell groups innervating specific hindlimb muscles (iliopsoas, adductors, and hamstrings) as well as axial muscles (medial longissimus and proximal tail muscles). The projection is bilateral, with a contralateral predominance. Ipsilaterally terminating fibers are derived from NRA neurons whose axons cross the midline at the level of the obex, descend through the contralateral spinal white matter, and recross at the level of termination. A conceptual description is presented in which the periaqueductal gray-NRA-lumbosacral projections form the final common pathway for lordosis in the cat.

Animals↗

PubMed1996

The clinical spectrum of limb girdle muscular dystrophy. A survey in The Netherlands.

A cross-sectional study was performed in the Netherlands to define the clinical characteristics of the various subtypes within the broad and heterogeneous entity of limb girdle muscular dystrophy (LGMD). An attempt was made to include all known cases of LGMD in the Netherlands. Out of the reported 200 patients, 105 who fulfilled strictly defined criteria were included. Forty-nine patients, mostly suffering from dystrophinopathies and facioscapulohumeral muscular dystrophy, appeared to be misdiagnosed. Thirty-four cases were sporadic, 42 patients came from autosomal recessive and 29 from autosomal dominant families. The estimated prevalence of LGMD in the Netherlands was at least 8.1 x 10(-6). The clinical features of the autosomal recessive and sporadic cases were indistinguishable from those of the autosomal dominant patients, although calf hypertrophy was seen more frequently, and the course of the disease was more severe in autosomal recessive and sporadic cases. The pectoralis, iliopsoas and gluteal muscles, hip adductors and hamstrings were the most affected muscles. Distal muscle involvement occurred late in the course of the disease. Facial weakness was a rare phenomenon. The severity of the clinical picture was correlated with a deteriorating lung function. All autosomal dominantly inherited cases showed a mild course, although in two families life-expectancy was reduced because of concomitant cardiac involvement.

Adolescent↗

PubMed2002

Hamstring injury in athletes: using MR imaging measurements to compare extent of muscle injury with amount of time lost from competition.

OBJECTIVE: The purpose of this study was to examine relationships between MR imaging measurements of the extent of hamstring injury and the amount of time lost from competition in a group of athletes. SUBJECTS AND METHODS: Thirty-seven athletes with suspected hamstring injury underwent T1 and inversion recovery T2 turbo spin-echo MR imaging in axial and sagittal planes. The presence and dimensions of abnormal focal intra- and extramuscular T2 hyperintensity were independently recorded by two radiologists, and the muscles involved and intramuscular location of injury were noted. The percentage of abnormal cross-sectional muscle area, abnormal muscle volume, and length of extramuscular T2 hyperintensity were measured from T2-weighted images depicting the maximal extent of the injury. Time (days) lost from competition was noted during follow-up. RESULTS: MR imaging detected hamstring muscle and linear extramuscular T2 hyperintensity in 30 (81%) and 25 (68%) of 37 athletes, respectively. The long head of the biceps was the dominant site of injury in 21 cases. The musculotendinous junction was involved in 28 (76%) of 37 cases. A relationship was seen between days lost from competition and percentage of abnormal muscle area (r = 0.63, p = 0.001) and volume of muscle affected (r = 0.46, p = 0.01), but only a trend for linear extramuscular T2 hyperintensity (r = 0.33, p = 0.12) was shown. CONCLUSION: Rehabilitation time was related to MR measurements such as the percentage of abnormal muscle area and approximate volume of muscle injury. Hamstring injury most frequently involved the long head of the biceps femoris muscle, and involvement of the intramuscular tendon was common.

Adolescent↗

PubMed2002

Changes in muscle torque following anterior cruciate ligament reconstruction: a comparison between hamstrings and patella tendon graft procedures on 45 patients.

We designed a prospective study to examine the influence of graft type (hamstring or patella tendon) on thigh muscle torque recovery after anterior cruciate ligament reconstruction. 60 patients undergoing ACL reconstruction, using a hamstring or patella tendon graft, were studied and 45 were followed up to 1 year. Concentric and eccentric quadriceps and hamstring torque were recorded, using an isokinetic dynamometer preoperatively, 6 and 12 months after ACL reconstruction. We found an improvement in all muscle functions in both the operated and unoperated legs during the recovery period. Graft type had no effect on recovery. During the first 6 months, torque was restored to preoperative levels and continued to improve in all muscles and actions between 6 months and 1 year.

Adult↗

PubMed1999

In situ forces in the human posterior cruciate ligament in response to muscle loads: a cadaveric study.

The objectives of this study were to determine the effects of hamstrings and quadriceps muscle loads on knee kinematics and in situ forces in the posterior cruciate ligament of the knee and to evaluate how the effects of these muscle loads change with knee flexion. Nine human cadaveric knees were studied with a robotic manipulator/universal force-moment sensor testing system. The knees were subjected to an isolated hamstrings load (40 N to both the biceps and the semimembranosus), a combined hamstrings and quadriceps load (the hamstrings load and a 200-N quadriceps load), and an isolated quadriceps load of 200 N. Each load was applied with the knee at full extension and at 30, 60, 90, and 120 degrees of flexion. Without muscle loads, in situ forces in the posterior cruciate ligament were small, ranging from 6+/-5 N at 30 degrees of flexion to 15+/-3 N at 90 degrees. Under an isolated hamstrings load, the in situ force in the posterior cruciate ligament increased significantly throughout all angles of knee flexion, from 13+/-6 N at full extension to 86+/-19 N at 90 degrees. A posterior tibial translation ranging from 1.3+/-0.6 to 2.5+/-0.5 mm was also observed from full extension to 30 degrees of flexion under the hamstrings load. With a combined hamstrings and quadriceps load, tibial translation was 2.2+/-0.7 mm posteriorly at 120 degrees of flexion ut was as high as 4.6+/-1.7 mm anteriorly at 30 degrees. The in situ force in the posterior cruciate ligament decreased significantly under this loading condition compared with under an isolated hamstrings load, ranging from 6+/-7 to 58+/-13 N from 30 to 120 degrees of flexion. With an isolated quadriceps load of 200 N, the in situ forces in the posterior cruciate ligament ranged from 4+/-3 N at 60 degrees of flexion to 34+/-12 N at 120 degrees. Our findings support the notion that, compared with an isolated hamstrings load, combined hamstrings and quadriceps loads significantly reduce the in situ force in the posterior cruciate ligament. These data are in direct contrast to those for the anterior cruciate ligament. Furthermore, we have demonstrated that the effects of muscle loads depend significantly on the angle of knee flexion.

Aged↗

PubMed2002

Developmental changes in compensatory responses to unexpected resistance of leg lift during gait initiation.

The development of the ability to integrate postural adjustments into the gait initiation process was investigated in children, using both kinematic and electromyographic (EMG) analysis. Subjects included children of 1 year of age (1-4 months' walking experience), 2-3 years of age (9-17 months' walking experience), 4-5 years of age (3-4 years' walking experience), and adults. We perturbed the balance of the children during gait initiation to determine the point at which infants begin to develop and finally master the ability to respond to external threats to balance during the gait initiation process. A magnet attached to the force platform on which the child stood was activated and served to resist the child's gait initiation (metal plaques on the soles of the shoes were attracted by the magnet) and thus served as an external perturbation during the gait initiation process. Kinematic and EMG analysis indicated that, while the ability to use preparatory postural adjustments in the gait initiation process emerges early in development, the ability to react efficiently to perturbations during gait initiation does not develop until after about 4-5 years of age. Though even the youngest age groups showed some response to the perturbation, it was highly variable, indicating its primitive form. The main response to the perturbation was a slight decrease in latency and increase in amplitude in the muscles used for push-off for gait initiation. Interestingly there was a shift in response pattern at 4-5 years of age, in both kinematic and EMG patterns. The amplitudes of the lateral and anteroposterior trunk and stance leg oscillations were significantly increased. In addition, the muscle response amplitudes (hamstrings and second quadriceps burst) of the swing leg were significantly increased and delayed (hamstring and gastrocnemius), with coactivation of agonist and antagonist muscles at the knee and ankle joint, concomitant with an exaggerated foot height of the first step.

Adaptation, Physiological↗

PubMedDate not supplied

An in vivo analysis of the effect of transcutaneous electrical stimulation of the quadriceps and hamstrings on anterior cruciate ligament deformation.

Transcutaneous electrical muscle stimulation (TEMS) has been advocated as a method to rehabilitate the postoperative ACL repaired/reconstructed lower extremity. Isolated quadriceps contraction can potentially disrupt the ACL repair/reconstruction; to minimize this risk simultaneous quadriceps and hamstring stimulation has been used. This study measured the in vivo deformation of the ACL during TEMS of the quadriceps and hamstrings. Six legs in four Rhesus monkeys were immobilized in 0 degrees, 45 degrees, and 90 degrees of flexion in neutral rotation using a Hoffman frame and pins placed through the proximal femur and distal tibia. The hamstrings and quadriceps muscles were stimulated with a dual channel electrical stimulator individually and simultaneously at each point of flexion, and ACL deformation was measured using a Hall effect device placed on the anterior medial fibers of the ACL. The following conclusions were made: 1) Isolated quadriceps contraction produces ACL elongation at 0 degrees and 45 degrees of knee flexion and produces ACL shortening at 90 degrees of knee flexion. 2) Isolated hamstrings contraction produces ACL shortening at 45 degrees and 90 degrees of knee flexion and negligible effects at full knee extension. 3) It is not possible to simultaneously contract the quadriceps and hamstrings using separate stimulator pads for each muscle group. 4) At 45 degrees of knee flexion when the quadriceps muscles are stimulated before the hamstring muscles and simultaneous contraction of both is then sustained, ACL lengthening occurs. 5) When the hamstring muscles are fired before the quadriceps muscles and simultaneous contraction of both is sustained, ACL shortening occurs.

Animals↗

PubMed2007

Muscle length and lengthening velocity in voluntary crouch gait.

The purpose of this study was to explore how origin-insertion length and lengthening velocity of hamstring and psoas muscle change as a result of crouch gait. The second purpose was to study the effect of changes in walking speed, in crouch, on muscle lengths and velocities. Eight healthy female subjects walked on a treadmill both normally and in crouch. In the crouch condition, subjects walked at three different walking speeds. 3D kinematic data were collected and muscle lengths and velocities were calculated using musculoskeletal modeling. It was found that voluntary walking in crouch resulted in shorter psoas length compared to normal, but not in shorter hamstrings length. Moreover, crouch gait did not result in slower muscle lengthening velocities compared to normal gait. These results do not support the role of hamstrings shortness or spasticity in causing crouch gait. Decreasing walking speed clearly reduced muscle lengths and lengthening velocities. Therefore, patients with short or spastic muscles are more likely to respond by walking slower than by walking in crouch. Also, differences in walking speed should be avoided as a confounding factor when comparing patient groups with controls.

Adult↗

PubMed2003

Effects of functional knee bracing on muscle-firing patterns about the chronic anterior cruciate ligament-deficient knee.

OBJECTIVE: To examine the effects of functional knee bracing on the muscle-firing patterns about the chronic anterior cruciate ligament (ACL)-deficient knee in successful brace users. DESIGN: Cross-sectional comparative clinical trial. SETTING: Motion analysis laboratory. PARTICIPANTS: Ten active individuals with unilateral, isolated, chronic (>18mo postinjury), ACL-deficient knees who subjectively reported improved function with a functional knee bracing. INTERVENTION: Each subject completed 3 single-leg hop maneuvers on their ACL-deficient knee with and without their knee brace while surface electromyographic activity was recorded from the quadriceps, hamstring, and gastrocnemius muscles. MAIN OUTCOME MEASURES: Muscle onset latency. RESULTS: Brace use significantly delayed the average onset of vastus lateralis activation before landing (123+/-47ms vs 109+/-30ms, P<.001), though significant interindividual variations existed. Bracing significantly altered the onset latency in 1 or more muscles in 9 of 10 subjects. In 4 subjects, a favorable change in the firing pattern was seen, whereas only 1 subject exhibited an unfavorable change. Without bracing, 5 of the 10 subjects fired the hamstrings or gastrocnemius muscles first; with bracing, 7 of 10 fired these muscles first. CONCLUSIONS: Brace use in this population did not consistently result in more favorable muscle firing patterns during the single-leg hop maneuver. Interindividual responses to brace use indicate the need for further research to investigate the multiple strategies that may exist to stabilize the ACL-deficient knee. In the meantime, functional knee brace use among ACL-deficient patients remains empirical.

Adolescent↗

PubMed1995

Testosterone administration to elderly men increases skeletal muscle strength and protein synthesis.

Aging men develop a significant loss of muscle strength that occurs in conjunction with a decline in serum testosterone concentrations. We investigated the effects of testosterone administration to six healthy men [67 +/- 2 (SE) yr] on skeletal muscle protein synthesis, strength, and the intramuscular insulin-like growth factor I (IGF-I) system. Elderly men with serum testosterone concentrations of 480 ng/dl or less were given testosterone injections for 4 wk to produce serum concentrations equal to those of younger men. During testosterone administration muscle strength (isokinetic dynamometer) increased in both right and left hamstring and quadricep muscles as did the fractional synthetic rate of muscle protein (stable-isotope infusion). Ribonuclease protection assays done on total RNA from muscle showed that testosterone administration increased mRNA concentrations of IGF-I and decreased mRNA concentrations of insulin-like growth factor binding protein-4. We conclude that increasing testosterone concentrations in elderly men increases skeletal muscle protein synthesis and strength. This increase may be mediated by stimulation of the intramuscular IGF-I system.

Aged↗

PubMed1999

Electromyographic timing analysis of forward and backward cycling.

PURPOSE: Backward walking to running progressions are becoming a popular, nontraditional component of functional knee rehabilitation programs. The purpose of this electromyographic (EMG) and motion analysis study was to compare the activation duration of the vastus medialis, vastus lateralis, rectus femoris, medial hamstrings, lateral hamstring, tibialis anterior, and gastrocnemius muscles during forward and backward cycling. We hypothesized that the hamstrings would demonstrate greater activation duration during backward cycling. METHODS: The right lower extremity of 12 healthy subjects (6 male and 6 female) was instrumented with surface EMG electrodes and retroreflective markers to confirm lower extremity kinematic consistency between conditions. RESULTS: Statistical analysis of hip, knee, and ankle kinematics (200 Hz sampling rate) and gender failed to reveal significant differences between conditions (P > 0.05). Quadrant analysis of muscle activation duration with Bonferroni corrections for multiple comparisons revealed that medial and lateral hamstring activation duration was greater during the early recovery phase (quadrant III) of backward cycling than forward cycling (P < 0.00156). Rectus femoris activation duration was greater in the early propulsive phase of backward cycling (quadrant 1) (P < 0.00156) and in the early recovery phase of forward cycling (quadrant III) (P < 0.00156). CONCLUSIONS: These findings lend support for the use of backward cycling during the early recovery phase (quadrant III) to achieve a selective hamstring muscle response of relatively decreased patellofemoral stress and anterior cruciate ligament strain.

Adult↗

PubMed2005

Interrater and intrarater reliability of the Modified Ashworth Scale in children with hypertonia.

PURPOSE: The Modified Ashworth Scale (MAS) is a six-point scale used to assess spasticity. This study assessed interrater and intrarater reliability of the MAS for children with hypertonia. METHODS: Five raters participated in this examination of interrater and intrarater reliability. The study included 17 children who showed hypertonus. Elbow flexor, hip adductor, quadriceps, hamstring, gastrocnemius, and soleus muscles were tested bilaterally. RESULTS: Results demonstrated good interrater reliability (intraclass correlation coefficient [ICC] >0.75) for elbow flexors and hamstrings and poor interrater reliability (ICC <0.50) for other muscles. Intrarater scores were good (ICC >0.75) for hamstrings and moderate (ICC = 0.50 to 0.75) for other muscles. CONCLUSION: Interrater reliability of the MAS may be lower than desired for clinical use for muscles other than hamstrings and elbow flexors, and intrarater reliability may also be lower than desired for muscles other than the hamstrings.

Child↗

PubMedDate not supplied

Intrinsic and extrinsic risk factors for muscle strains in Australian football.

Muscle strains are common injuries in Australian football and other sports involving sprinting. Between 1992 and 1999, 83,503 player-matches in the Australian Football League were analyzed for risk of muscle strain injuries using logistic regression analysis. There were 672 hamstring, 163 quadriceps, and 140 calf muscle strain injuries. All three types of muscle strains were associated with significant risk factors. For all injuries, the strongest risk factor was a recent history of that same injury and the next strongest risk factor was a past history of the same injury. History of one type of muscle strain increased the risk for certain types of other muscle strains. Age was a risk factor for hamstring and calf muscle strains (even when adjusted for injury history) but was not a risk factor for quadriceps muscle strains. Quadriceps muscle injuries were more common in shorter players and were more likely when there had been less rainfall at the match venue in the previous week. Quadriceps muscle injuries were significantly more common in the dominant kicking leg, whereas hamstring and calf muscle injuries showed no difference in frequency between the dominant and nondominant legs.

Adult↗