To assess exercise tolerance in clinical practice, various functional tests are used (with dosed exercise, change in body position, breath holdings, etc.). The greatest practical distribution was received by the PWC 170 test , based on the notion of a linear (within certain limits) nature of the relationship of the heart rate
(HR) and the power of physical work (W). It is believed that at a pulse frequency of 170 beats / min, a limiting mode of operation of the cardiorespiratory system is noted with maximum oxygen consumption. Therefore, physical performance conditionally expressed in terms of the capacity of physical activity, at which the heart rate = 170 in 1 min. Hence the name PWC 170 — Physical Working Capaciti, i.e. capacity for maximum physical exertion. This test is generally accepted and officially recommended by WHO. Most often it is used according to the method of V.L. Karpman using two standard bicycle ergometric loads (70 W and 130 W for 5 minutes each) with a two-minute rest between them. The indicator is calculated according to the formula:
170 —f 1 PWC 170 = N 1 + (N 2 —N 1 ) . ———,
f 2 —f 1 where —N 1 is the power of the 1st load, in W; N 2 —the power of the 2nd load, in W; f 1 – HR
at the end of the 1st load; f 2 —ChSS at the end of the 2nd load. The lower limit of the normal rate is 150 watts.
The method also allows you to calculate other indicators — the pulse cost of work, the pulse amount of work, and the pulse amount of recovery. As a dosed exercise, climbing a step can also be used (step test). The technique consists in a two-minute rise of the investigated one step at a height of 50 cm at a rate of 30 times per minute. Evaluation of the results of the sample is carried out on the index of the test (I).
T. 100 I = —————,
(P 2 + P 3 + P 4 ) . 2 where T is the sample time (s); P 2 , P 3 , P 4 —frequency rate in the first 30 seconds 2, 3, 4 minutes
recovery period after the load. The index is normally 40— units. Very informative is also a sample of Rufe. The subject produces 30 squats in 45 s. Results are evaluated by the change in heart rate. Pulse is counted for 15s (P 1 ) after a 5-minute calm state, then after squats, the pulse is counted for the first 15s (P 2 ) and the last 15 s (P 3 ) for the first minute after the end of the load. Index (I) is calculated
according to the formula:
4 (P 1 + P 2 + P 3 ) – 200 I = —————-
ten The value of I is estimated as follows:
from 0.1 to 5 — differently from 5.1 to 10 — well, from 10.1 to 15 — satisfactory
from 15.1 to 20 is bad. Orthostatic test. In the supine position, the patient is counted
pulse rate, after which he is offered to stand up smoothly, without sudden movements. During the first 15 seconds in a standing position counting the pulse. Evaluation of the sample is made in accordance with the data presented.