Affiliations: [a] Service de physiologie du sport, Hopital Tamier, Paris, France
Note: [*] Address reprint requests to A. Duvallet, Service de physiologie et medecine du sport, Hopital Tarnier, 89 rue d'Assas, 75006 Paris, France.
Abstract: The aim of this study was to investigate the response of heart rate during functional isokinetic testing of muscle. Testing involved unilateral use of the flexor and extensor muscles of the thigh (knee test). After a 10-min warm-up on a cycle ergometer, one leg was tested after the other, starting with the dominant limb. Exercise involved 5-sec isometric tests with extension, and then flexion at 0, 30 and 60 deg, isokinetic tests at 60 and 180 deg/sec, and a 30-movement endurance test at 180 deg/sec. Heart rate was recorded on average over 5 sec and was analyzed at the start and end of exercise. Mean values were determined for 25 regular participants in sporting activities: distance running (n = 6), rugby (n = 11), and diverse recreational sports (n = 8). Respective increases in heart rate during exercise for the first and second legs were 50 and 67% in isometry, 87 and 102% at 60 deg/sec, 67 and 83% at 180 deg/sec, and 135.5 and 142.5% in endurance. Maximal values were reached in endurance testing, with respective means of 156.3 ± 16 bpm and 160.9 ± 17 bpm for the first and the second leg. Analysis of the individual curves for each subject showed maximal values of 181 and 188 bpm, i.e., 93 and 96.5% of the maximum theoretical heart rate (220 – age). Three minutes after testing the heart rate was 93.3 ± 16.8 bpm, i.e., 41.3% above the pretest resting rate. The results demonstrate the importance of the heart work rate imposed by these tests, which only brings into play a relatively limited muscle mass. The endurance test, which is more strenuous, should only be used with subjects free of cardiac risks. This study confirms that an isokinetic test must be performed under the supervision of an appropriate clinician, who should judge the value and feasibility of the endurance test.
