Cardiorespiratory Responses To Incremental Exercise In Young And Middle-aged Sedentary Men

The general behavior of cardiorespiratory responses during incremental exercise are well established. However, these responses can be influenced by factors such as age, gender, physical performance, genetic factors and others. The purpose of this study was to verify the peak oxygen uptake (%Oi peak), the peak workload and the venn'latory anaerobic threshold (AT) in two groups of brazilian sedentary men: Gl (n=15) x=2lyr and 02 (n=10) 55=53 yr. Dynamic exercise tests were applied in a cicloergometer (Quinton, in sitting position) using a continuous protocol up to physical exhaustion, with direct measuremment of the VOi (MMCSensormedics). The results (medians) for the groups were: 02 peak (ml/Kg/min)= 38(G1) and 27.3(02) (p<0.05); WL peak(Watts)= 212(01) and 163(02) (p<0.05); AT(%VO2 peak)= 64%(G1) and 67.2%(G2). These results have shown that during incremental exercises most of the studied parameters were higher in the younger group, with the exception of AT (%O2 peak) which showed differences not statiscally significant. Research support: FAEP-UNICAMP, FAPESP & CAPES, e-mail: [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