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.

Exercise performance during captopril and atenolol treatment in hypertensive patients.

1. Maximal aerobic exercise capacity, submaximal endurance exercise performance, and exercise haemodynamics have been studied in sixteen patients with mild to moderate essential hypertension during treatment with captopril and atenolol. 2. Administration of atenolol (1 x 100 mg day-1) or captopril (1 x 100 mg day-1) for 6 weeks resulted in similar supine and erect systolic and diastolic blood pressures. Heart rate was significantly lower during atenolol treatment. 3. Exercise heart rate and systolic blood pressure were significantly lower during atenolol than during captopril treatment, exercise diastolic blood pressure (at 100W) did not differ significantly. With atenolol exercise cardiac output was significantly lower and exercise stroke volume significantly higher than with captopril. 4. Maximal work rate, maximal oxygen consumption and maximal heart rate were significantly lower during atenolol than during captopril treatment (respectively 6%, 8% and 25%). Maximal respiratory exchange ratio and lactate concentration did not differ. 5. No statistically significant difference in submaximal endurance time between atenolol and captopril was found. Endurance time was reduced by 19% during atenolol and by 13% during captopril as compared with placebo. No difference in rating of perceived exertion between atenolol and captopril was present. 6. The results indicate that atenolol will reduce blood pressure during exercise more effectively than captopril in patients with hypertension. The limitation of submaximal endurance exercise performance by both agents is of similar magnitude. This may be regarded as an unwanted side effect in certain physically active patients with hypertension.

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.

Exercise haemodynamics and maximal exercise capacity during beta-adrenoceptor blockade in normotensive and hypertensive subjects.

1. The effects of atenolol administration on maximal exercise capacity and exercise haemodynamics have been compared in eight normotensive and eight mildly hypertensive subjects, matched for sex, age, body weight, and maximal oxygen uptake, and familiar with maximal exercise testing. 2. Supine and exercise blood pressure, and exercise total peripheral resistance were significantly higher, and exercise cardiac output was significantly lower in the hypertensive than in the normotensive subjects. 3. Administration of atenolol (1 X 100 mg day-1) for 3 days reduced supine and exercise systolic blood pressure, heart rate, and cardiac output, and increased exercise stroke volume. Supine and exercise diastolic blood pressure and exercise total peripheral resistance were unaffected by atenolol. The effects of atenolol did not differ in the normotensive and the hypertensive subjects. 4. Maximal work load, maximal oxygen uptake, and maximal heart rate were reduced to a similar extent in normotensive and hypertensive subjects during atenolol treatment. 5. It is concluded that there is no difference in the effects of short-term atenolol administration on exercise haemodynamics and maximal exercise capacity in normotensive and mildly hypertensive subjects.