Isokinetic aerobic power output testing of the quadriceps muscle.

A stepwise increasing exercise protocol to measure the maximal aerobic power output of the quadriceps muscle is proposed for use in rehabilitation medicine. Sixteen healthy volunteers performed isokinetic knee extension/flexion exercises at an angular velocity of 180 degrees x s(-1). The protocol consisted of stages of 200 knee movements from 100 flexion to full extension, starting at 10% peak torque (PT) and increasing by 10% PT each following stage until exhaustion. Quadriceps work, oxygen uptake, heart rate, plasma lactate concentration and surface electromyography were monitored. Quadriceps power output (Pext) was highly related (r = 0.95) to the extension torque at which the subjects were instructed to exercise. The test-retest (r = 0.82) and left to right (r = 0.94) correlations of maximum quadriceps power output (Pmax) were high. Both sexes (males 43+/-9W, females 36+/-8W) achieved their Pmax at 47% PT. At submaximal power output stages oxygen uptake (r = 0.85) and EMG-amplitude (r = 0.88) were linearly related to Pext. Mechanical efficiency (optimum at 60% Pmax) showed a large variation between power output stages and between subjects. The relationship between relative oxygen uptake and heart rate or plasma lactate concentration was similar to that of whole body exercise, e.g. running. We conclude that the proposed test is reliable for assessing the maximal aerobic power output of the quadriceps muscle. This parameter of the muscle function may add useful information for assessing the rehabilitation process after knee immobilization.

Effects of cast-bracing of the knee on physical performance in healthy subjects.

Effects of application of a hinged cast-brace on thigh muscle strength and physical performance tests were studied in eight healthy volunteers. The cast-brace was applied to one leg for four weeks. The subjects were free to move around. The extra loading by the cast-brace was determined in a progressive uphill walk test on a treadmill with measurements of oxygen uptake, heart rate and plasma lactate concentration. Submaximal oxygen uptake in the uphill walk test was raised significantly (average 9%) on the day after application. After four weeks of cast-brace wearing the submaximal oxygen uptake in the uphill walk test had decreased, but remained elevated (average 4%) even one day after removal. Heart rate was significantly higher (average 7%) during cast application and after removal. Plasma lactate concentration, however, was not influenced. To investigate the effect of four weeks cast-bracing various performance tests to judge the thigh muscle function were taken before application and after removal. No significant changes in peak torque of knee flexion and extension, in physiologic variables at submaximal running pace during treadmill exercise, maximal running speed, 60 m dash, or in jump height were found. In conclusion, cast-bracing of a healthy knee for four weeks has no significant effects on physical performance after removal.

[Ankle sprains. Comparison of long-term results of functional treatment methods with adhesive tape and bandage ("brace") and stability measurement]. / Das Knöchelinversionstrauma. Vergleich der Langzeitergebnisse funktioneller Behandlungsmethoden mit Klebeverband und Bandage ("Brace") und die Eignung der Stabilometrie.

Both taping and bracing can be applied in the early functional treatment of ankle sprains. In this study the long-term (2.3 +/- 0.5 years) results of functional treatment with two types of bandages were compared. Out of 165 patients treated, 112 were available for interview, 60 of whom had been treated with adhesive, non-elastic tape and 52, with a confection brace. In 93 of these patients (47 in the tape group), the ankle was examined and stabilometry was performed. The distance (D) and area (A) covered by each patient's centre of gravity while he/she stood on one leg for 30 s were measured. The following symptoms were found on the total population: pain on movement in 5%, swelling in 8% and functional instability (recurrent sprain or a feeling of giving way) in 38%. Mechanical instability was found in 34%. Pain on palpation of the lateral ligaments was the only symptom whose frequency differed significantly (P < 0.05) between the tape group (47%) and the brace group (20%). Stabilometric measurements revealed no substantial difference between the tape group (D: 436 +/- 100 mm; A: 192 +/- 87 mm2) and the brace group (D: 459 +/- 111 mm; A: 206 +/- 92 mm2). Nor was any difference in stability observed between the injured and the non-injured ankle, between the stable and the unstable ankle, or between the unstable ankle with and without brace application. Stabilometry is thus not an appropriate means of quantifying the symptoms of ankle instability.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional and morphological adaptations following four weeks of knee immobilization.

Immobilization of the knee as part of the treatment in bone or joint lesions leads to atrophy and consequently loss of functionally. In patients this atrophy and loss of functionality is difficult to quantify because of interfering symptoms and missing baseline data. In the present study structural and functional changes in thigh muscles were examined in eight healthy volunteers of whom one leg was immobilized in a cast for four weeks. Quadriceps cross-sectional area determined with computed tomography was 21% +/- 7% diminished after four weeks immobilization (p < 0.05). Muscle biopsies from the musculus vastus lateralis revealed an 16% decreased fiber diameter (p < 0.05) and no significant shift in fiber types. Isokinetic strength measurements of knee extensors and flexors demonstrated a fall in peak torque of 53% +/- 9% and 26% +/- 13% at an angular velocity of 60 deg.s-1 (p < 0.01). Aerobic power in one-leg-cycling exercise was not significantly affected, but isokinetic quadriceps endurance work decreased from 9.1 kJ to 5.6 kJ (p < 0.05). Despite the fall in quadriceps performance the subjects had only minor functional complaints for a few days. It is concluded that immobilization of the knee is an important factor in the development of thigh muscle atrophy in patients and should therefore be diminished as much as possible.

The effects of a supportive knee brace on leg performance in healthy subjects.

Eight healthy volunteers were fitted with a supportive knee brace (Push Brace 'Heavy') to one knee for a duration of four weeks wherein they were tested before, during and after the application to establish the effect of bracing on performance. The tests consisted of isokinetic strength measurement of knee flexion and extension, 60 meter dash, vertical jump height and a progressive horizontal treadmill test until exhaustion (Vmax) with determination of oxygen uptake, heart rate and plasma lactate concentration. Wearing the brace for one day, the performance indicators showed a decline compared with the test before application (base values). Sprint time was 4% longer (p less than 0.01) and Vmax 6% slower (p less than 0.01). Peak torque of knee flexion at 60 and 240 deg.sec-1 was 6% (p less than 0.05) respectively 9% (p less than 0.05) less. Peak extension torque at 60 deg.sec-1 was 9% less (p less than 0.05). While wearing the brace for four weeks, the test performances were practically identical to their base values. After removal of the brace, all test parameters were statistically similar to the base values. Heart rate at submaximal exercise levels was even lower (p less than 0.05). In conclusion, performance in sports with test-like exercise patterns is not affected by the brace tested. Bracing does not "weaken the knee" as it is widely believed in sports practice.

Transposition of the semitendinosus tendon for early repair of medial and anteromedial laxity of the knee.

In 15 patients with acute medial (N = 8) or anteromedial (N = 7) laxity of the knee, reconstruction of the torn ligaments was combined with the use of the semitendinosus tendon as a dynamic extra-articular stabilizer. The postoperative regimen consisted of early mobilization in a mobile cast with full weight bearing. An evaluation 1 to 3 years after surgery revealed good results in 14 cases, and one fair result as graded using the Marshall score (mean score 45.3, SD 2.9). Isokinetic measurements of knee flexion and extension showed no loss of strength. Equally good results have been reported in conservatively treated isolated MCL lesions. In case of a combination of a MCL lesion and an ACL lesion the results reported are usually worse. This treatment regimen seems to be a good concept in acute anteromedial laxity of the knee and cannot be considered anything but an alternative in isolated MCL lesions.

Early functional treatment of supination-eversion stage-II ankle fractures: preliminary results.

The preliminary results of early functional treatment of 30 patients with a grade-II supination-eversion fracture of the ankle according to Lauge-Hansen are discussed. The treatment of all patients consisted of splint immobilization for one week, followed by the application of a functional brace (Push Brace Medium) and immediate full weight bearing and functional training. All fractures healed without complications. Ankle function, radiographic findings and anamnestic complaints were monitored. The loss of ankle function diminished to 3.2 degrees +/- 4.9 degrees plantar flexion and to 1.7 degrees +/- 5.3 degrees dorsal flexion after one year follow up, none of the patients had significant complaints of pain or swelling. Radiography showed consolidation with callus formation in all cases. The grade-II supination-eversion fracture is a stable fracture which allows early functional treatment with the support of a Push Brace Medium. This results in an inexpensive, simple and comfortable therapy. A prospective randomized clinical trial is necessary to show the advantages of functional treatment over cast immobilization. Long-term follow-up will have to ascertain the theoretic risk of posttraumatic osteo-arthritis.