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PubMed1991

A useful technique for measurement of back strength in osteoporotic and elderly patients.

Improvement of back extensor strength (BES) can be used as a therapeutic method for patients with chronic back pain and osteoporosis. The method of evaluation must be reliable and accurate without compromising the condition of the patient. We report the development of a back isometric dynamometer (BID-2000) designed specifically by two of us to address these concerns in elderly patients with osteopenia or osteoporosis. As the demographics of the general population change, increasing numbers of patients will need the type of monitoring that the BID-2000 provides. Aging has been shown to cause a reduction in the number of functional muscle motor units. To examine this effect on BES, we tested 50 normal, healthy women who were 30 to 79 years old. Proper testing of BES in patients with fragile vertebrae should include isometric measurement in the prone position, maneuverability of the device to allow comfortable positioning of the patient, and simplicity of technique to minimize repetitious performance of maximal contraction. The BID-2000 incorporates each of these features and also provides meaningful results inexpensively. The device offers a safe, reliable (coefficient of variation = 2.33%), and valid (P = 0.001) method of evaluation. The results of our study demonstrated moderate, steady reduction of BES with increasing age and with each successive decade.

Adult↗
PubMed1990

Effects of eccentric and concentric resistance training on skeletal muscle substrates, enzyme activities and capillary supply.

This study compared the skeletal muscle metabolic adaptations in response to combined eccentric and concentric or concentric resistance training regimens. Twenty-six physically active males were assigned to either the combined eccentric and concentric group (n = 10), the concentric group (n = 10) or the control group (n = 6). The combined eccentric and concentric and the concentric groups performed four to five sets of maximal, voluntary bilateral quadriceps muscle actions at 1.05 rad s-1 using a speed-controlled dynamometer three times per week for 12 weeks. The concentric group performed 12 concentric actions per set, whereas the combined eccentric and concentric group performed six coupled eccentric and concentric actions per set. Bilateral percutaneous muscle biopsies were obtained from m. vastus lateralis at rest pre- and post-training. Tissue samples were analysed for contents of adenosine triphosphate, creatine phosphate and creatine and for enzyme activities of citrate synthase, lactate dehydrogenase, myokinase, phosphofructokinase, hexokinase and Mg2(+)-ATPase using fluorometric techniques. Histochemical staining procedures were employed to determine capillary supply. The overall increase (P less than 0.05) in muscle strength was greater (P less than 0.05) for the combined eccentric and concentric group than for the concentric group. Enzyme or substrate contents and capillary supply were unaltered after either type of training. It is suggested that substantial increases in muscle strength may occur in response to resistance training without enhancing or compromising metabolic function of skeletal muscle.

Adaptation, Physiological↗
PubMed2001

Knee extension strength and vertical jumping performance in nordic combined athletes.

BACKGROUND: The purpose of this study was to measure knee extension strength and vertical jumping performance characteristics in nordic combined athletes. METHODS: Unilateral knee extension isometric maximal force (MF) and rate of force development (RFD) were measured by a special dynamometer, and unilateral isokinetic peak torque (PT) at angular velocities of 60 and 180 deg/sec by a Cybex II dynamometer. Maximal squat (SJ) and counter-movement jumps (CMJ) were performed on force platform. Nine nordic combined athletes as the experimental group and 12 untrained male university students as the control group participated. RESULTS: Nordic combined athletes had a greater (p<0.05) absolute and relative (body mass-related) values of knee extension isometric MF and isokinetic PT, isometric RFD as well as jumping height in SJ and CMJ, than controls. The jumping height in CMJ was greater (p<0.05) compared with SJ only in nordic combined athletes. Jumping height in SJ and CMJ correlated significantly (p<0.05) with knee extension isometric RFD (r=0.62-0.83) and isokinetic PT at angular velocity of 60 deg/sec (r=0.70-0.82) in nordic combined athletes and untrained men. No significant correlation was obtained between unilateral knee extension isometric MF and isokinetic PT or vertical jumping height. CONCLUSIONS: The present study demonstrated a markedly higher voluntary maximal and explosive force-generating capacity of the extensor muscles of lower extremities in nordic combined athletes compared with untrained men, which indicates the adaptation to specific explosive type of strength training.

Adult↗
PubMed1990

Strength training for wheelchair users.

Sedentary adult males with spinal lesions, all habitual wheelchair users, were allocated to exercise (n = 11) and control (n = 4) groups. A Cybex II dynamometer was used to assess peak power, average power, total work and muscular endurance for elbow flexion/extension, shoulder flexion/extension and shoulder abduction/adduction at five angular velocities, on recruitment and after eight and 16 weeks of forearm ergometer training (three days/week). Small sub-groups of the exercised subjects were assigned to high or low intensity endurance effort (70 or 40 per cent of maximal oxygen intake) and long or short training sessions (40 or 20 minutes per session). Despite the aerobic nature of the activity, gains of average power were registered by the two muscle groups most involved in the ergometer task (shoulder extension and elbow flexion). In keeping with current theories of training, gains were largest with prolonged, high intensity activity at angular velocities approximating those adopted during training.

Adolescent↗
PubMed2000

Mechanical performance and electromyography during repeated maximal isokinetic shoulder forward flexions in female cleaners with and without myalgia of the trapezius muscle and in healthy controls.

This cross-sectional study aimed at investigating the influence of occupational exposure to static and highly repetitive work involving the neck and shoulder muscles, myalgia of and tender point in the trapezius muscle on biomechanical output, and electromyogram (EMG) variables (mean frequency MNF, signal amplitude and ability to relax) during maximal forward flexions of the shoulder muscles. Groups of 25 cleaners suffering from chronic myalgia of the trapezius muscle, 25 cleaners free from myalgia of the trapezius muscle and 21 teachers performed 150 forward flexions using an isokinetic dynamometer. Perception of fatigue was reported and surface EMG was recorded from four muscles during the endurance test. The cleaners were stronger than the teachers. Myalgia was associated with lower levels of endurance and a high degree of perceived fatigue. The ability to relax the trapezius muscle decreased with age and was even lower in cleaners with and without myalgia. Higher MNF of the deltoid muscle but not of the trapezius muscle was found in the group suffering from myalgia compared to the groups free from myalgia. This cross-sectional study indicated that myalgia of the trapezius muscle did not influence the strength but did influence the endurance of the forward flexor muscles of cleaners. The observed decrease in the ability to relax the trapezius muscle in cleaners compared to healthy teachers might be indicative of a future insufficiency in the muscle. Prospective studies are needed to define the significance of the results presented here.

Cross-Sectional Studies↗
PubMed2002

A comparison of the effects of exercise and lifestyle modification on the resolution of overuse symptoms of the shoulder in polio survivors: a preliminary study.

OBJECTIVE: To compare the effectiveness of exercise and lifestyle modification therapy in treating shoulder symptoms in polio survivors with lower-extremity weakness. DESIGN: A randomized parallel group study. SETTING: Research laboratory. PARTICIPANTS: Twenty-three subjects recruited from a cohort of 194 polio survivors who had participated in a previous study had bilateral hip-extensor and knee-extensor weakness and reported experiencing shoulder pain on a regular basis with daily activity. INTERVENTIONS: Subjects were randomly assigned to 1 of 3 treatment groups. Members of group 1 were placed on a home exercise program that focused on strengthening their hip and knee extensors. Members of group 2 were instructed in lifestyle modification techniques designed to avoid shoulder overuse. Members of group 3 received both interventions. MAIN OUTCOME MEASURES: Shoulder symptoms were quantified in terms of number and severity. Isometric strength of bilateral hip and knee extensors was measured with a hand-held dynamometer. RESULTS: Symptoms improved in all 3 groups. However, members of the exercise-only group (group 1) were the only ones to show a significant difference in both number and severity of symptoms when pre- and posttreatment values were compared. CONCLUSIONS: Both exercise and lifestyle modification therapies that focus on reducing the stress related to lower-extremity weakness are effective in treating shoulder overuse symptoms in polio survivors. A trend toward greater improvement in shoulder symptoms in subjects who participated in the exercise program and who also showed a trend toward increased knee-extensor strength supports muscle strength and/or endurance as a key factor.

Aged↗
PubMed2006

Duration of stretch does not influence the degree of force loss following static stretching.

AIM: There is an emerging body of knowledge indicating static stretching (SS) acutely and adversely affects muscle performance. The practical value of this research is limited considering the lengthy stretch durations under investigation. It is unclear if stretch durations typical of those used pre-exercise similarly affect muscle performance. The purpose of this study was to determine if SS using more representative stretch durations affects muscle performance and to establish if changes in muscle performance were influenced by the duration of stretch. METHODS: Following 2 familiarization sessions, 16 recreationally trained males and females participated in 2 randomly ordered experimental sessions. In each session maximal effort hamstring performance was assessed prior to and immediately after 1 of 2 stretching protocols. During one of the protocols participants were required to hold each stretch for 15 s while stretch duration in the second protocol was 30 s. Both protocols consisted of 3 repetitions of 2 stretching exercises. A Kincom isokinetic dynamometer was used to assess hamstring performance during isometric, concentric, and eccentric actions. RESULTS: For each of the three muscle actions a repeated measures ANOVA revealed a significant main effect of time (pre- vs poststretch, P<0.05) but no interaction effect (time x SS protocol). Furthermore, the stretch-induced deficits in muscle performance were consistent across muscle action type. CONCLUSIONS: SS incorporating stretch durations typical of those employed pre-exercise were sufficient to impair muscle performance and the duration of stretch did not influence the degree of force loss. Inclusion of SS, even with short stretch durations, in preparation for strength activities is not appropriate.

Adult↗
PubMed1998

Leg extensor power and quadriceps strength: an assessment of repeatability in patients with osteoarthritic knees.

OBJECTIVE: To assess the repeatability of two muscle function measures -- leg extensor power (LEP) and isometric quadriceps force (IQF) -- in a population of patients with osteoarthritis of the knee. DESIGN: Repeat measures of LEP and IQF at 25 degrees and 50 degrees knee flexion were taken within seven days. Both legs were measured and a numerical rating scale was used to assess pain on the two occasions. SUBJECTS: Patients who were on a waiting list for a primary unilateral knee replacement for osteoarthritis were invited to take part in the study. SETTING: The physiotherapy department of a National Health Service Orthopaedic Hospital in Oxford, UK. INTERVENTION: Subjects were measured using a Kin-Com dynamometer to assess maximum isometric force and a leg extensor power rig to assess maximum single leg explosive power. RESULTS: Twenty-six patients (mean age: 72 years; SD: 8 years; range: 50-87 years) were included in the study following informed consent. A weak relationship was found between LEP, IQF and pain scores which reached the 5% significance level for the LEP measures only. The level of repeatability for both measures was found to be acceptable. CONCLUSION: Both LEP and IQF are recommended as repeatable measures for assessment of muscle function in patients with osteoarthitis of the knee. However, the LEP rig has the added advantage of being quicker, cheaper and simpler to use in the clinical setting.

Aged↗
PubMed2004

Anterior cruciate ligament reconstruction with double-looped semitendinosus and gracilis tendon graft directly fixed to cortical bone: 5-year results.

Forty-three patients who had undergone an anterior cruciate ligament (ACL) reconstruction using a doubled semitendinosus and gracilis graft were prospectively reviewed at 5-year follow-up. All had suffered subacute or chronic tears of the ligament. At surgery, the femoral tunnel was drilled first through the antero-medial portal. The correct position of the femoral and tibial guide wire was checked fluoroscopically. A cortical fixation to the bone was achieved in the femur with a Mitek anchor, directly passing the two tendons in the slot of the anchor, and in the tibia with an RCI screw, supplemented with a spiked washer and bicortical screw. Rehabilitation was aggressive, controlled and without braces. The International Knee Documentation Committee (IKDC) form, KT-1000 arthrometer, and Cybex dynamometer were employed for clinical evaluation. A radiographic study was also performed. At the 5-year follow-up all the patients had recovered full range of motion and 2% of them complained of pain during light sports activities. Four patients (9.5%) reported giving-way symptoms. The KT-1000 side-to-side difference was on average 2.1 mm at 30 lb, and 68% of the knees were within 2 mm. The final IKDC score showed 90% satisfactory results. There was no difference between the 2-year and 5-year evaluations in terms of stability. Extensor and flexor muscle strength recovery was almost complete (maximum deficit 5%). Radiographic study showed a tunnel widening in 32% of the femurs and 40% of the tibias. A correlation was found between the incidence of tibial tunnel widening and the distance of the RCI screw from the joint (the closer the screw to the joint, the lower the incidence of widening). In conclusion, we can state that, using a four-strand hamstring graft and a cortical fixation at both ends, we were able to achieve satisfactory 5-year results in 90% of the patients.

Adolescent↗
PubMed1991

Isometric back strength of low back pain patients and healthy controls.

The primary objective of this study was to determine the back strength of low back pain patients and to compare their values with healthy control subjects. Using the back and leg dynamometer, we measured the isometric back strength of 21 patients (14 men and 7 women), with chronic low back pain and 21 (14 men and 7 women) healthy (control) subjects. Both groups are comparable (p greater than 0.05) in age, body weight, height and Quetelet index (weight/height2). The back strength of the low back pain patients is not significantly (p greater than 0.05) different from their sex, age and anthropometric matched healthy controls. However, the males in the study were stronger (p less than 0.01) than their female counterparts. Based on our findings, we conclude that weakness of the paraspinal extension muscles is not the likely primary cause of idiopathic low back pain.

Adult↗
PubMed2005

Treatment of chronic inflammatory demyelinating polyneuropathy with high-dose intermittent intravenous methylprednisolone.

BACKGROUND: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) causes progressive disability due to weakness but responds to immunomodulating medication, including oral prednisone and intravenous (IV) immunoglobulin (IVIg). However, there is no consensus on initial therapy, and both of these treatments have drawbacks with long-term treatment. OBJECTIVE: To review the efficacy and safety of high-dose, intermittent IV methylprednisolone (IVMP) as initial and long-term maintenance therapy for patients with CIDP. DESIGN: A retrospective medical record review between 1992 and 2003 of outcomes in CIDP, comparing patients in 3 cohorts depending on whether their primary treatment was IVMP, IVIg, or oral immunosuppression with prednisone or cyclosporine. SETTING: Washington University Neuromuscular Disease Center (St Louis, Mo), outpatient and inpatient records. PATIENTS: Patients with clinical and electrophysiologic evidence of CIDP were identified. Of 57 patients, 39 had sufficient data for full analysis. MAIN OUTCOME MEASURES: Quantitative muscle testing with a handheld dynamometer. Medication profiles and adverse effects were also recorded. RESULTS: There was no significant difference in the mean improvement in quantitative muscle testing at 6 months or at the last clinic visit (an average of 4.5 years later) among the 3 groups. Fewer patients treated with oral immunosuppression improved at 6 months, but at the last visit, 81% to 88% improved in all 3 groups. Less weight gain and fewer cushingoid features affected patients treated with IVMP (19%) compared with patients treated with oral prednisone (58%). CONCLUSIONS: Treatment of patients with CIDP using high-dose intermittent IVMP results in improved strength equal to that with IVIg and oral prednisone. The frequency of occurrences of weight gain and cushingoid features with IVMP is less than that with oral prednisone. Intravenous methylprednisolone should be considered for initial and long-term therapy in CIDP when patients have disability due to weakness.

Administration, Oral↗
PubMed1996

The effect of tourniquet use on postoperative strength recovery after arthroscopic meniscectomy.

The purpose of this prospective study was to determine the effect of pneumatic tourniquet use during arthroscopic meniscectomy on postoperative recovery of quadriceps and hamstring strength. Thirty-four patients with no ligamentous instability underwent arthroscopic meniscectomy after random assignment to the tourniquet or no tourniquet group. Tourniquet pressure was determined with a nomogram that considered thigh circumference and systolic blood pressure at time of induction. Quadriceps and hamstring strengths were tested preoperatively and at 1 week and 4 weeks postoperatively on a Biodex isokinetic dynamometer and expressed as a percentage of the uninvolved side. No significant differences in quadriceps or hamstring strength were noted between groups at any time periods. The findings of this study indicate that recovery of quadriceps and hamstring strength after arthroscopic meniscectomy is not adversely affected by tourniquet use if tourniquet times and pressures are carefully controlled.

Adolescent↗
PubMedDate not supplied

Soft tissue composition, quadriceps strength, bone quality and bone mass in rheumatoid arthritis.

OBJECTIVES: To examine differences in soft tissue composition, bone quality, bone mass and quadriceps strength between women with rheumatoid arthritis (RA) and healthy controls. METHODS: 79 women with RA (median disease duration 10 yrs) were studied. Most were or had been on steroids. 67 healthy age-matched women served as controls. The lean tissue mass (LTM) and fat mass (FM) of the total body and of the major body subregions, as well as the bone mineral density (BMD, g/cm2) of the femoral neck, spine (L2-L4) and distal forearm were measured by dual energy x-ray absorptiometry (DXA). Bone quality expressed as the speed of sound (SOS m/sec), broadband ultrasound attenuation (BUA, dB/MHz) and stiffness was assessed by an Achilles ultrasound device, and isometric quadriceps strength by an isokinetic dynamometer. RESULTS: No between-group differences were found for the body mass index (BMI, weight/height2), total or regional percentage fat, LTM and FM. However, women with RA had 20% lower quadriceps strength than controls. BMD at the femoral neck and distal forearm, and SOS, BUA and stiffness were significantly lower in patients than in controls. No difference was found for spine BMD. In the RA group, z-scores for SOS and stiffness were significantly more reduced than those for BMD. Multiple regression analyses indicated negative associations between ultrasound parameters and the cumulative steroid dose. CONCLUSIONS: Reductions in BMD and muscle strength in RA were not accompanied by changes in soft tissue composition, Bone quality assessed by ultrasonography was compromised in RA and may be modified by steroids.

Absorptiometry, Photon↗
PubMed1991

Hand-held myometry: reference values.

In thirteen major muscle groups of 50 healthy females and 50 males, aged 20-60 years, maximum voluntary contraction was measured with a hand-held dynamometer. The intrasession variation, the left-right variation, and the fifth and fiftieth centile values were calculated. The ratio of two observations within one session ranged from 0.85 to 1.18 and the ratio of left to right ranged from 0.82 to 1.22 (95% reference limits). In 20 volunteers the repeatability was tested after one week. The ratio of averages of three measurements in two successive weeks ranged from 0.82 to 1.23 (95% reference limits). There were only small differences between muscle groups concerning these ratios. A significant relation with age and weight/Quetelet Index could be demonstrated in some muscle groups. The mean strength of females is approximately two thirds of the strength of males. The data may be useful as reference values in the application of hand-held myometry.

Adult↗
PubMedDate not supplied

Torque-velocity relationships of the knee extensor and flexor muscles in individuals sustaining injuries of the anterior cruciate ligament.

Muscle deficits in 58 patients with chronic anterior cruciate ligament (ACL) insufficiency were evaluated after completion of a 6 month rehabilitation program. Quadriceps and hamstring torques were measured on a modified Cybex II isokinetic dynamometer. Twenty-nine of our patients were tested just prior to undergoing ACL reconstruction, and patients who were continuing to tolerate their conditions served as controls. For the surgical group, significant quadriceps deficits (P less than 0.01) were found for all speeds and at both the 30 and 60 degrees positions. The nonsurgical group had significant deficits at the 30 degrees position at 180 degrees/sec, and at 60 degrees for the 0 degree/sec and 30 degrees/sec. However, in comparing the two groups no significant differences were noted. Regarding hamstring deficits in the surgical group, significant deficits were seen only at 30 degrees of flexion at 180 degrees/sec. The nonsurgical group had similar deficits. Of interest was the observation that the hamstring:quadriceps (H:Q) ratio was found to be both speed-position dependent. Overall, no correlation was found between the presence of strength deficits following a rehabilitation program and the need for surgery.

Adolescent↗
PubMed1991

Static dynamometer for the measurement of multidirectional forces exerted by the thumb.

The functioning of a static dynamometer designed to measure simultaneous forces exerted by the thumb in the vertical and horizontal axes is described. The analysis of the output signals by a desktop computer program provides information regarding the forces generated in eight directions covering a plane transverse to the thumb by 45 degree increments. In 12 normal female subjects, the maximum voluntary torques exerted at the trapezo-metacarpal joint of the thumb were examined and the muscle activation patterns of the interosseus, flexor pollicis brevis and adductor pollicis brevis muscles were recorded in one subject. Torques and muscle activation patterns were depicted using polar plots. Dynamometric data indicate that strength varies with direction and that higher torques are obtained in directions that bring the thumb towards the palm, i.e. flexion, adduction, combined flexion-adduction and extension-adduction. Patterns of muscle activity vary according to the direction evaluated suggesting that strength depends on the number of activated muscles as well as the relative force contribution of each muscle.

Calibration↗
PubMed1991

Standardization of grip strength measurements. Effects on repeatability and peak force.

The aim of our study was to test grip strength and assess the effects of various degrees of standardization on repeatability and level of peak force. Sixteen healthy persons and eight subjects with an impaired hand function have been tested using a strain-gauge dynamometer. We compared four measurement protocols: (A) the subject is free to assume a comfortable arm position; (B) the subject is also free to assume a comfortable arm position but in addition a challenging stimulus to exceed a previous maximal effort, is given; (C) the arm was held in a predescribed and partly fixated position, as recommended by the American Society of Hand Therapists; (D) the position of the dynamometer is standardized using two reference points both on the hand and on the dynamometer. We found high test-retest reliabilities for each measurement protocol without any significant difference. There were, however, significant differences in strength level. With measurements according to protocol B the highest peak values were noted. Since the measurement protocol B combined good reliability with realistic peak forces, this procedure seems most suitable for grip strength measurements.

Adolescent↗
PubMedDate not supplied

A biomechanical evaluation of tibiofemoral rotation in anterior cruciate deficient knees during walking and running.

ACL injury has been associated with increased instability of the knee in both in vitro and in vivo studies using passively applied forces. This study assessed tibiofemoral rotation after ACL injury during the functional activity of treadmill ambulation using a triaxial electrogoniometer. Isometric and isokinetic peak torques of the quadriceps and hamstrings were obtained using the Cybex II isokinetic dynamometer. Significant increases in tibiofemoral rotation were noted with increased running speed in the injured and normal knees. The degree of rotation in the injured limb did not significantly exceed that of the normal limb. Isokinetic strength of the quadriceps and hamstrings correlates significantly with the observed extent of rotation.

Adult↗