Study Of Cardiorespiratory Variables At The Anaerobic Threshold (at) In Trained And Sedentary Subjects

The AT is a parameter which signals the moment of equilibrium loss between the supply and demand of oxygen during the performance of dynamic exercise(DE). This physiological parameter is dependent on to the type of physical training and has been used in the evaluation of aerobic capacity. This study aimed to analyze the cardiorespiratory variables at the moment of the AT. DE tests were applied using a continuous protocoKCP) up to physical exhaustion with direct measurement of the oxygen uptakeCv'Oa ). The studied groups included: 5 sedentary subjects(S); 5 long distance runners(LDR) and; 5 weight lifters(WL). The values (medians) of cardiorespiratory variables determined at the AT were as follows: a) O2 (mI/kg/min.)=18.5(S), 20(WL) and 29.9(LDR)(p<0.05 between LDR and the other groups); bjheart rate (HR-bpm)=120(S),120(WL),120(LDR);c)AHR from rest to the AT=+36(S),+42(WL), and+66(LDR)(p<0.05 between LDR and S); d) power(watts)=50(S),100(WL),100(LDR)(p<0.05 between LDR and S); e) ventilation (l/min)=34.1(S),35.9(WL),40(LDR). These data have shown the occurrence of prominent cardiorespiratory adaptations with increase of aerobic power in LDR group, when compared to the other studied groups (S and WD.Research support: FAEP-UNICAMP& FAPESP. [email protected]

Cardiorespiratory Responses During Dynamic Exercise Using Different Ergometers In Sedentary

The peak oxygen uptake (O: peak) and the ventilatory anaerobic threshold (AT) has been used in the evaluation of aerobic capacity. To evaluate the response of these parameters in different ergometers, 15 healthy sedentary young men (f=21 yr) were submitted to three dynamic exercise tests with direct VOz measurement (MMC-Sensormedics): a) in the cicloergometer (Quinton, sitting position), using a continuous protocol with power increments between 12 to 20 Watts/min up to physical exhaustion; b) in treadmill (Quinton) two tests, one with constant slope of 0% (EO) and the other with constant slope of 10% (E10), both with increments of 0.5 km/min up to physical exhaustion. The results (medians) were: 'frOj at rest (ml/kg/min)= 4.5(C), 4.9(EO), 5.1(E10) (p<0.05 between C and EO and between C and E10); Oj peak(ml/kg/min)= 38(C), 46.6(EO), 48.7(E10) (p<0.05 between C and EO and between C and E10); AT (%Oj peak)= 64(C), 52.4(EO), 57.3(E10). These data have shown that 'v'Oz obtained in treadmill at rest and peak are greater than that obtained in cicloergometer. On the other hand, the AT expressed as percentual value of $Ch peak showed differences not statiscally significant. Research support: FAEPUNICAMP, FAPESP & CAPES, e-mail: [email protected]

Effects of aerobic exercise training on heart rate variability during wakefulness and sleep and cardiorespiratory responses of young and middle-aged healthy men

The purpose of the present study was to evaluate the effects of aerobic physical training (APT) on heart rate variability (HRV) and cardiorespiratory responses at peak condition and ventilatory anaerobic threshold. Ten young (Y: median = 21 years) and seven middle-aged (MA = 53 years) healthy sedentary men were studied. Dynamic exercise tests were performed on a cycloergometer using a continuous ramp protocol (12 to 20 W/min) until exhaustion. A dynamic 24-h electrocardiogram was analyzed by time (TD) (standard deviation of mean R-R intervals) and frequency domain (FD) methods. The power spectral components were expressed as absolute (a) and normalized units (nu) at low (LF) and high (HF) frequencies and as the LF/HF ratio. Control (C) condition: HRV in TD (Y: 108, MA: 96 ms; P<0.05) and FD - LFa, HFa - was significantly higher in young (1030; 2589 ms²/Hz) than in middle-aged men (357; 342 ms²/Hz) only during sleep (P<0.05); post-training effects: resting bradycardia (P<0.05) in the awake condition in both groups; VO2 increased for both groups at anaerobic threshold (P<0.05), and at peak condition only in young men; HRV in TD and FD (a and nu) was not significantly changed by training in either groups. The vagal predominance during sleep is reduced with aging. The resting bradycardia induced by short-term APT in both age groups suggests that this adaptation is much more related to intrinsic alterations in sinus node than in efferent vagal-sympathetic modulation. Furthermore, the greater alterations in VO2 than in HRV may be related to short-term APT