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PubMed1998

High thigh muscle strength but not bone mass in young horseback-riding females.

To evaluate whether the type of weight-bearing loading subjected to the skeleton during horseback-riding was associated with differences in bone mass and muscle strength of the thigh, we investigated bone mass and isokinetic muscle strength in 20 female horse riders (age 17.9 +/- 0.6 years) who were riding 7.0 +/- 3.4 hours/week, and 20 nonactive females (age 17.8 +/- 1.1 years). The groups were matched according to age, weight, and height. Areal bone mineral density was measured in total body, head, lumbar spine, right femoral neck, Ward's triangle, and trochanter, the whole dominant and nondominant humerus, and in specific sites in the right femur diaphysis, distal femur, proximal tibia, and tibia diaphysis using dual X-ray absorptiometry. Isokinetic concentric and eccentric peak torque of the quadricep and hamstring muscles were measured using an isokinetic dynamometer. There were no significant differences in bone mass between the horseback riders and nonactives at any site measured. The horse riders were significantly (P < 0.05-0.01) stronger in concentric hamstrings strength at 90 degrees/second and 225 degrees/second and in eccentric quadricep and hamstring strength at 90 degrees/second. Horseback riding in young females is associated with a high muscle strength of the thigh, but not with a high bone mass.

Adolescent↗

PubMed1990

Differential responses to proprioceptive neuromuscular facilitation (PNF) stretch techniques.

The purpose of this study was to investigate the effects of sustained stretch and two common proprioceptive neuromuscular facilitation (PNF) stretch techniques on hamstring muscle activation and knee extension range of motion (ROM) in different athletic populations. Three stretch techniques: stretch-relax (SR), contract-relax (CR), and agonist contract-relax (ACR) were applied to 10 endurance athletes (EN), 10 high intensity athletes (HI), and 10 control subjects (C). The results revealed that ACR produced 89-110% greater hamstring EMG activity (P less than 0.05) and 9-13% more knee joint ROM than CR and SR, respectively. This same pattern was evident for the individual subject groups. Comparisons of mean data among the three subject groups revealed that the EN athletes generated 58-113% more hamstring EMG activity (P less than 0.05) than the HI and C groups, respectively, across all stretch conditions, whereas the EN group attained significantly less ROM than the HI and C groups for CR and ACR conditions. It was postulated that high intensity-short term activity training necessitates less hamstring resistance to knee extension than long term endurance training. The findings suggest that decreases in muscle activity may not be strongly related to increases in joint range of motion and that factors other than muscle relaxation are important in achieving increased ROM. Also, the differential effects of various stretch techniques between dissimilar athletic populations should be considered if stretch-induced injury is to be avoided.

Adult↗

PubMed1999

Forward leaning reaching task in sitting (FLRS): a new measure for clinical evaluation of hamstring length in children.

BACKGROUND AND PURPOSE: In this study, the rotation of the pelvis was taken into account when assessing the length of hamstrings. A new measure for clinical evaluation was developed to establish reference values of hamstring length in children without movement disabilities for different age groups. Subjects (N = 60) were 3-, 6-, 10- and 14-year-old children (N = 15 for each age group). These values could be helpful in deciding treatment interventions in children with movement disabilities, for example cerebral palsy, when hamstring length is in question. METHOD: The study was performed with subjects sitting and reaching for a touch control on a wall whilst voluntarily rotating the pelvis forwards. By use of digitized video frames, the spatial angles of the lumbar spine and pelvis, as well as the joint angles of hip and knee, were computed at the initial and end positions of a forward leaning reaching task in sitting (FLRS). The active forward leaning induced a forward rotation of the pelvis, causing stretch on the hamstring muscle with extended knee. RESULTS: The results of spatial and joint angle measurements suggest that the difference of the hip joint angle between initial erect and final forward leaned sitting may be used as reference values for hamstring length. Reference values are based on the mean (+/- SE) of means (mean of 15 children, that is, group and individual means of ten trials). CONCLUSIONS: The age group reference values obtained may indirectly give information as to whether the hamstring length of a child with cerebral palsy is within the normative value of age-related control subjects. The new test developed in this study provides a convenient means for measuring hamstring length and could enhance clinical evaluation.

Adolescent↗

PubMed2006

Comparison of the efficacies of botulinum toxin A and Johnstone pressure splints against hip adductor spasticity among patients with cerebral palsy: a randomized trial.

OBJECTIVE: The goal was to compare the efficacies of botulinum toxin A (BTX) treatment and Johnstone pressure splint (JPS) treatment against hip adductor muscle spasticity among children with spastic diplegic cerebral palsy. METHODS: For each patient in the BTX group, a total of 300 IU of BTX was injected into adductor and medial hamstring muscle groups. In the JPS group, long leg JPS were administered for 30 minutes 3 days per week. Bobath neurodevelopmental exercises were administered to both groups 3 days per week during the study period. All cases were assessed by using gross motor function measurements, passive hip abduction goniometric measurements, modified Ashworth Scale scores, and measurements of the distance between the knees as indicator variables. RESULTS: We found that there was statistically significant improvement in all indicators for both groups. BTX treatment was found to be superior to JPS treatment in terms of the indicator variables of our study.

Adolescent↗

PubMed2006

Incidence of injury in elite Gaelic footballers.

The purpose of this study was to undertake a comprehensive prospective epidemiological study of injuries sustained by elite Gaelic Football players over one season. The pattern of injury is strikingly similar across all teams with 47% of all injuries occurring in the final quarter of games and training. Injuries to the lower limb, particularly the hamstrings muscles accounted for the majority of injuries. 65% of players were unable to participate fully in Gaelic Football activity for between one and three weeks as a result of injury. The high incidence of injury especially hamstrings injuries in the latter stages of training and games warrants further investigation.

Adolescent↗

PubMed1988

Ankle muscle activity during gait in children with cerebral palsy and equinovarus deformity.

Temporal electromyographic (EMG) characteristics of lower limb muscles during gait of spastic hemiplegic and diplegic children with cerebral palsy are described. All subjects were referred for presurgical evaluation of equinovarus deformity. The data indicated both similar and discriminating phasic EMG characteristics between groups of patients. All children displayed premature triceps surae activity beginning in swing phase of gait and continuing through stance. Tibialis posterior, normally active during stance, was also active during swing phase of gait. However, some patients displayed cocontraction of triceps surae and tibialis anterior during stance, together with hamstring muscle activity within normal limits. The remainder of the patients displayed a prolonged duration of hamstring activity. How this gait analysis contributed to presurgical decisions for equinovarus gait is discussed and compared with data from postsurgical gait analysis.

Ankle↗

PubMed2002

The evolution of hindlimb tendons and muscles on the line to crown-group birds.

The anatomy and functions of muscle-tendon complexes and their bony attachments in birds and their outgroups show how the major pelvic limb muscle groups evolved. Fossils reveal that most changes evolved after the divergence of archosaurs in the Triassic, particularly in the dinosaurian precursors to birds. Three-dimensional limb control became concentrated at the hip joint; more distal joints and muscles were restricted to flexion or extension early in dinosaur evolution. Hip extensors expanded even though the primary femoral retractor M. caudofemoralis longus was reduced. Hip flexors and two-joint "hamstring" muscles were simplified to a few large heads. Knee extensors increased their sizes and moment arms early in bipedal dinosaurs, but the patella and cranial cnemial crest evolved later in birds. Lower limb muscles expanded as ossifications such as the hypotarsus increased their moment arms. The ossification of lower limb tendons, particularly in extensors, is a recent novelty of birds. Muscles and tendons that develop large forces, stresses, and moments to stabilize or move the limbs became increasingly prominent on the line to birds. Locomotion evolved in a stepwise pattern that only recently produced the derived limb control mechanisms of crown-group birds, such as the strongly flexed hip and knee joints.

Animals↗

PubMed1986

Serial isokinetic evaluations used for a patient with scapuloperoneal muscular dystrophy. A case report.

This article reports the reversal of an atypical rapid decline in muscle strength experienced by a patient with scapuloperoneal muscular dystrophy by modulating his excessive daily physical activity. This process was aided by our monitoring the strength of the quadriceps femoris and hamstring muscles using an isokinetic dynamometer. Serial torque values for muscle strength were compared as the total daily physical activity was decreased systematically. The torque values for thigh muscle strength increased as the subject's total work load was decreased. A complete management program for neuromuscular patients should include specified amounts of daily physical activity, rest, and therapeutic exercise.

Adult↗

PubMed2005

Effect of dry needling of gluteal muscles on straight leg raise: a randomised, placebo controlled, double blind trial.

OBJECTIVES: To use a randomised, double blind, placebo controlled trial to establish the effect on straight leg raise, hip internal rotation, and muscle pain of dry needling treatment to the gluteal muscles in athletes with posterior thigh pain referred from gluteal trigger points. METHODS: A randomised, double blind, placebo controlled trial of 59 male runners was performed during the 2002 Australian Rules football season. Subjects were thoroughly screened and had magnetic resonance imaging of their hamstring muscles to exclude local pathology. The inclusion criterion was reproduction of recognisable posterior thigh pain with the application of digital pressure to the gluteal trigger points. Subjects randomly received either therapeutic or placebo needle treatment on one occasion at their gluteal trigger points. Range of motion and visual analogue scale data were collected immediately before, immediately after, 24 hours after, and 72 hours after the intervention. Range of motion was measured with passive straight leg raise and hip internal rotation. Visual analogue scales were completed for hamstring and gluteal pain and tightness at rest and during a running task. RESULTS: Magnetic resonance imaging scans revealed normal hamstring musculature in most subjects. Straight leg raise and hip internal rotation remained unchanged in both groups at all times. Visual analogue scale assessment of hamstring pain and tightness and gluteal tightness after running showed improvements immediately after the intervention in both groups (p = 0.001), which were maintained at 24 and 72 hours. The magnitude of this improvement was the same for therapeutic and placebo interventions. Resting muscle pain and tightness were unaffected. CONCLUSIONS: Neither dry needling nor placebo needling of the gluteal muscles resulted in any change in straight leg raise or hip internal rotation. Both interventions resulted in subjective improvement in activity related muscle pain and tightness. Despite being commonly used clinical tests in this situation, straight leg raise and hip internal rotation are not likely to help the therapist assess response to treatment. Patient reports of response to such treatment are better indicators of its success. The mechanisms by which these responses occur and the reasons for the success of the placebo needling treatment are areas for further investigation.

Acupuncture Therapy↗

PubMed1992

Effect of knee joint laxity on long-loop postural reflexes: evidence for a human capsular-hamstring reflex.

The onset latency and discharge amplitude of preprogrammed postural responses were evaluated in order to determine if the structure of synergistic activation could be altered by ligamentous laxity at the knee joint. Twelve subjects with unilateral and one subject with bilateral anterior cruciate ligament (ACL) insufficiency were tested while standing on a moveable platform. External balance perturbations (6 cm anterior or posterior horizontal displacements of the platform) were presented at velocities ranging from 15 to 35 cm/s. Perturbations were presented under the following experimental conditions: unilateral and bilateral stance, knees fully straight or flexed, and with ankle motion restricted or free. These stance, knee position, and ankle motion conditions were introduced to alter the stress transmitted to the knee joint during movement of the support surface. The automatic postural response was recorded from the tibialis anterior (T), quadriceps (Q), and medial hamstrings muscles (H) bilaterally. The normal response to an externally induced backward sway involved the automatic activation of T and Q at latencies of 80 ms and 90 ms respectively. Activation of the hamstrings in the non-injured extremity was not coupled with the postural response. Hamstrings are not typically involved in the correction posterior sway because H activation would tend to pull the center of mass further backwards. However, when the response in the ACL-deficient extremity was compared to the non-injured limb: (1) the automatic postural response in the ACL-deficient extremity was restructured to include hamstrings activation (100 ms latency), (2) H activation time was faster and less variable in the ACL-deficient limb, and (3) the ratio of H/Q discharge amplitude integrated over 100 ms and 200 ms from the onset of EMG activation showed a dominance of hamstring activity during unilateral stance on the lax limb. In addition, H/Q ratios integrated over 200 ms showed dominant hamstring activity in the ACL-deficient limb during bilateral stance. (4) Cross-limb comparisons showed greater normalized IEMG amplitudes for T, H, and Q during unilateral stance on the lax limb. These results suggest that a capsular-hamstring reflex is integrated into the existing structure of a preprogrammed postural synergy in order to compensate for ligamentous laxity. Furthermore, the generalized increase of response gain observed during perturbations of unilateral stance on the lax limb indicates that joint afference can modulate central programming to control localized joint hypermobility. A concept of postural control is discussed with respect to the capsular reflex, joint loading and displacement of the center of gravity.

Adolescent↗

PubMed1998

A biomechanical evaluation of cyclic and static stretch in human skeletal muscle.

The short term effect of static and cyclic stretch paradigms on stiffness and maximal joint range of motion was examined in 12 recreational athletes. To assess flexibility, joint range of motion and resistance to stretch were measured using a dynamometer during a passive stretch of the hamstring muscle group to the point of pain. The recorded torque-angle curve allowed for identification of maximal joint range of motion and calculation of passive muscle-tendon stiffness and energy. Three flexibility assessments (stretch 1 - 3), each 10 min apart, were administered to each leg. A 90 s static stretch and 10 cyclic stretches were performed after the second stretch on the left and right side, respectively. Stiffness in a common range for stretch 1 - 3 was unchanged on both the left and right side. However, on the left side (static stretch) there was a significant effect of flexibility assessment (stretch 1 - 3) (p < 0.0001) with an increased maximal joint angle (p < 0.01) and maximal stiffness (p < 0.05) between all three stretches. Similarly, on the right side (cyclic stretches) there was a significant effect of flexibility assessment (p < 0.0001) with an increased maximal joint angle between stretch 1 and 3 (p < 0.01) and maximal stiffness (p < 0.05) between all stretches. During the static stretch passive torque declined 35+/-4% (p < 0.001). During the cyclic stretches passive energy and hysteresis both declined 17% (p < 0.05) while stiffness increased 12% (p < 0.05). The results of the present study demonstrate that static and cyclic stretching, as it is commonly performed by athletes, increases joint range of motion by increasing stretch tolerance while the viscoelastic characteristics of the muscle remain unaltered.

Adult↗

PubMed1997

Influences of muscle stretch reflexes on voluntary, velocity-controlled movements in spastic paraparesis.

We studied voluntary, velocity-controlled knee movements in 22 patients with spastic paraparesis (11 male, 11 female) and 22 healthy controls (11 male, 11 female). Torque and EMG activity of the quadriceps and the hamstring muscles were determined in maximal voluntary concentric (shortening) and eccentric (lengthening) actions of knee extensor and flexor muscles at constant movement velocities of 30, 60, 120 and 180 degrees/s, using an active, isokinetic dynamometer. In the spastic patients, the voluntary strength and the agonist EMG activity were reduced in all movements. The reduction was largest in concentric actions at high velocity. The antagonist EMG activity was reduced in the same proportion as the agonist EMG activity in eccentric actions. In concentric actions when stretch is imposed upon antagonists, the antagonist EMG activity increased with the velocity of stretch, indicating stretch reflex activation. In parallel with the stretch reflex activation of antagonists, there was reduced activation of the agonists compatible with Ia reciprocal inhibition of agonist motoneurons. When agonists were stretched in eccentric actions, stretch reflexes appeared to support the voluntary, agonist activation of knee flexor muscles but not knee extensors.

Adult↗

PubMed1998

Transcutaneous electrical stimulation of thigh muscles in the treatment of detrusor overactivity.

OBJECTIVE: To investigate the clinical effects on detrusor overactivity of a new method of transcutaneous reciprocal electrical stimulation of the thigh muscles. PATIENTS AND METHODS: Nineteen patients with detrusor overactivity, comprising 14 with detrusor hyperreflexia (DH) and five with idiopathic detrusor instability (IDI), were studied. Electrical stimulation was applied alternately to the quadriceps and hamstring muscles of one or both legs through surface electrodes for 20 min. The treatment was given once a day for 14 days and then the patients were evaluated urodynamically. RESULTS: All 19 patients tolerated the therapy well and none reported any adverse effects. The mean maximum cystometric capacity increased significantly (P < 0.05) after treatment. In 11 of the 19 patients, the maximum cystometric capacity was increased by > 50% of the pretreatment value; this occurred in eight of 14 of those with DH and in three of five of those with IDI. In six of the 11 who responded in this way, there was a clinical improvement in their urinary incontinence and frequency for several weeks to 3 months after the period of therapy. A second 14-day treatment was also effective in all four patients who underwent a repeat trial. CONCLUSION: This method of transcutaneous electrical stimulation can inhibit DH as well as IDI with no adverse effects. The suppressive effect on detrusor overactivity may persist for several months and repeat trials appear to be effective. Thus, we believe that this new stimulation technique should be tried as an alternative to other types of electrical stimulation and augmentation cystoplasty.

Adult↗

PubMed1997

Intermuscular co-ordination during fast contact control leg tasks in man.

From previous inverse dynamic analyses of human leg extensions, it was hypothesized that the underlying processes for the activation of mono- and biarticular muscles are different; the mono-articular muscles being activated when they shortened, whereas the biarticular muscles appeared responsible for the control of the external force direction. In the present study, experiments were performed on a dynamometer which was especially developed to test this hypothesis. Subjects had to exert different prescribed force vectors on a moving force-plate during leg extension, which they had intensively practised prior to the actual experiments. Of each trial, position, force and EMG activity were recorded. Net joint torques were calculated by the method of inverse dynamics and related to the EMG-patterns of the mono- and biarticular upper leg muscles to reveal whether the previously observed different roles in contact tasks might constitute a general principle in motor control. The results showed that although the action of the biarticular m. rectus femoris and hamstrings muscles was consistent in controlling the direction of the external force, the actions of the mono-articular muscles did not agree with their hypothesized role as simple work generators. The generalizability of a different control for mono- and biarticular muscles could thus not be confirmed for these tasks. They might rather reflect one out of more available strategies the CNS can use to control different contact control tasks.

Adult↗

PubMedDate not supplied

Long-term expression of a fluorescent reporter gene via direct injection of plasmid vector into mouse skeletal muscle: comparison of human creatine kinase and CMV promoter expression levels in vivo.

Expression of a fluorescent reporter gene has been studied using two alternate promoters to transcribe the green fluorescent protein (gfp) from Aequorea victoria. The human cytomegalovirus (CMV) enhancer/ promoter or the human muscle-specific creatine kinase promoter (CKM) were inserted along with the gfp cDNA into a plasmid expression vector based on a modified adeno-associated virus genome. Naked plasmid DNA was injected into the hamstring muscle of mdx mice and gfp gene expression determined from frozen muscle sections taken at 4, 14, and 42 days postinjection. Fluorescence patterns obtained by photomicroscopy and quantitative fluorescence measurements indicated a near-linear increase in the accumulation of the gfp in skeletal muscle during the length of the study, with gfp expression at 42 days being roughly four times the values obtained at 4 days. The levels of expression of gfp from the CKM construct were consistantly higher than for the CMV construct. The CKM promoter/expression vector combination demonstrates significant potential for simple, direct delivery and long-term, high-level expression of genes in skeletal muscle.

Animals↗

PubMed1987

Non-surgical management of overuse knee injuries in runners.

Seventy-three injured runners (45 men, 28 women) who presented with 83 running-induced overuse knee injuries were managed conservatively. The regimens utilized focused on quadriceps and hamstring muscle retraining and the control of functional overpronation. Patello-femoral pain syndrome (42 cases) was by far the most common problem. The next most common problems were iliotibial band friction syndrome (10), patellar tendonitis (9) and popliteal tendonitis (5). The most frequent etiological factor was a sudden increase in training mileage. Following the initial visit and at regular intervals throughout the recovery phase, quadriceps and hamstring capacities were determined on a Cybex II isokinetic unit at 60 degrees/second and 180 degrees/second. Significant differences (p less than 0.01) in Cybex scores were observed between strong and weak extremities in males and females for both muscle groups at both velocities. The mean Cybex scores and the differences with muscle groups between strong and weak legs for the subjects were similar to those reported for healthy non-athletes. The treatment protocol followed four basic principles: control of pain; rebuilding of muscle strength and endurance; improvement of bio-mechanical efficiency and gradual reintroduction of training. No significant changes in the differences between strong and weak leg Cybex scores occurred between the initial and final evaluations, except in the male group when the hamstrings were evaluated at 60 degrees/second (p less than 0.01). In the 82 cases managed non-surgically, 1 poor, 8 fair, 36 good and 37 excellent results were obtained. The authors believe that the significance of disturbance in quadriceps and hamstring function to the etiology of overuse knee injuries may be increased in runners who over-pronate.

Adolescent↗

PubMed2003

Gender differences in surface rolling and gliding kinematics of the knee.

The purpose of the current study was to determine whether knee surface rolling and gliding kinematics differed between genders during open and closed kinetic chain movement conditions. Eleven unimpaired adults (six men and five women) participated in this study. Sagittal plane path of instant center of rotation measurements were obtained with videographic motion analysis and applied to a mathematical knee model from which joint surface rolling and gliding kinematics were obtained. In addition, normalized electromyographic data were collected from subjects' quadriceps and hamstring muscles. During closed kinetic chain knee extension, as the knee approached terminal extension, female participants showed significantly greater relative joint surface gliding than male participants. Female participants also extended the knee in the closed kinetic chain with less relative hamstring activity than males. The relationship between joint surface gliding and relative hamstring activity in females during closed kinetic chain knee extension may explain, in part, the greater incidence of noncontact anterior cruciate ligament injury that occurs in females.

Adult↗

PubMed2005

Strength around the hip and flexibility of soft tissues in individuals with and without patellofemoral pain syndrome.

STUDY DESIGN: Case control design. OBJECTIVES: To investigate whether differences exist in lower extremity muscle strength and soft tissue length between patients with patellofemoral pain syndrome (PFPS) and age- and gender-matched control subjects. BACKGROUND: Based on our clinical experience and emerging data, impairments such as muscular weakness surrounding the hip and limited flexibility of key lower extremity muscles may be important impairments to consider in the conservative management of PFPS. METHODS AND MEASURES: Thirty patients with PFPS and 30 age- and gender-matched controls without PFPS (17 females and 13 males in each group) participated in the study. Data were collected during 1 testing session by an examiner not blinded to group assignment. Demographic, health history, physical activity levels, and pain and function were assessed using patient-completed measures. Physical examination measures included assessment of hip external rotation strength, hip abduction strength, length of the iliotibial band/tensor fascia lata complex, gastrocnemius length, soleus length, and quadriceps and hamstrings muscles length. RESULTS: Patients with PFPS demonstrated significantly less flexibility of the gastrocnemius, soleus, quadriceps, and hamstrings compared to healthy control subjects. No differences existed in flexibility of the iliotibial band/tensor fascia lata complex and strength of the hip external rotators and abductors. Multivariate stepwise discriminant analysis identified gastrocnemius length, hip abduction strength, and soleus length as being able to distinguish between patients with PFPS and healthy individuals without PFPS. CONCLUSION: This study suggests that further research is warranted regarding the association of these impairments of muscle strength and soft tissue length in patients with PFPS.

Adult↗