PREDICTION OF ACCEPTABLE PHYSICAL WORK LOADS BASED ON RESPONSES TO PROLONGED ARM AND LEG EXERCISE

Nine healthy men (aged 54-59 years) performed arm crank and leg cycle exercises for 30 min at relative work loads of 50 and 75% of peak oxyg en uptake (VO2) for the corresponding muscle group, and for 60 min at a relative work load of 30% of peak VO2 for the corresponding muscle g roup. In the tests, heart rate (HR), blood pressure, gas exchange vari ables, rating of perceived exertion (RPE) and blood lactate were measu red. At the 75% target exercise level, four subjects interrupted the a rm-cranking test, and one subject interrupted the leg-cycle test. Owin g to differences in peak values during arm-cranking and leg-cycling, t he work load and the VO2 were higher during leg-cycling than during ar m-cranking. There was no difference in HR between the work modes, but the HR increased to a greater extent during arm-cranking compared to l eg-cycling at the 30% (NS) and 50% (P < 0.05) exercise levels. Similar ly, the RPE increased more during arm-cranking compared to leg-cycling at each exercise level. The blood lactate concentration was higher af ter arm-cranking than after leg-cycling; at the 50% exercise level the difference was statistically significant. The results indicate a high er physiological strain with time during arm exercise than during leg exercise at the same muscle group-specific relative work load. The acc eptable physical work load, expressed as the percentage peak VO2 for t he corresponding muscle group, should thus be lower during arm exercis e than during leg exercise. The RPE and the relative HR, expressed as percentage of peak HR for the corresponding muscle group, however, see m to be comparable indicators for the physiological strain during arm and leg exercise.