Exercise prescription based upon cardiac vagal activity for middle-aged obese women

Abstract

OBJECTIVE:The purposes of this study were to examine a new method to determine exercise intensity for obese people based on the cardiac vagal activity and to determine the effect of this approach on myocardial stress. SUBJECTS: Forty-three middle aged obese female volunteers (age 43.7 AE 6.5 y; height 1.56 AE 0.05 m; body mass 66.5 AE 9.3 kg; body mass index 27.3 AE 2.8 kg m 2 ; percentage body fat 40.7 AE 5.9%). MEASUREMENT: In the first experiment, 43 subjects performed a ramp exercise test on a bicycle ergometer with measurement of ECG and gas exchange parameters. In the second experiment, 11 subjects performed 45 min of constant walking exercise on a treadmill at a level corresponding to exercise intensity determined by vagal activity obtained from a ramp bicycle test. Blood pressure, endothelin 1 (ET-1), catecholamine, atrial natriuretic peptide (ANP), and brain natriuretic peptide (BNP) were measured before and after exercise. RESULTS: The heart rate variability power decreased with increasing work rate, and changed little after reaching individualspecific work rate. We presumed that vagal activity disappeared at this point and that the heart rate at this exercise intensity was determined as the vagal activity threshold (T VA ). The results showed a significant positive correlation (r ¼ 0.742, P < 0.0001) between T VA and ventilatory threshold (VT) heart rates, although the mean heart rate of T VA (114.3 AE 8.5 beats=min) was significantly lower (P < 0.001) than that at VT (119.0 AE 11.7), suggesting the cardiac vagal withdrawal occurred prior to the onset of lactate acidosis (lactic acid accumulation). Furthermore, exercise intervention experiment at T VA indicated that ET-1, catecholamine and BNP levels were not significantly different before and after exercise. However, ANP levels increased significantly after exercise (pre-exercise 18.6 AE 5.38 vs post-exercise 44.0 AE 24.87 pg=ml, P < 0.001), which in turn brought about a significant post-exercise reduction in the blood pressure (SBP 117.6 AE 13.7 vs 110.5 AE 7.4 mmHg, P < 0.05; DBP 78.6 AE 6.7 vs 73.5 AE 6.6 mmHg, P < 0.01). CONCLUSION: Our data suggest that it is possible to determine the exercise intensity (T VA ) on the basis of cardiac vagal response. These results also suggest that exercise at T VA level is a safe exercise intensity in the light of cardiac stress, and that T VA may be recommended for obese people who might possess lower cardiac sympatho-vagal activity.

Noninvasive method to estimate anaerobic threshold in individuals with type 2 diabetes

“…In the present study the HRVT, as identified through the quantitative analyses of the Poincaré plots (SD1), occurred at exercise intensities not different to the LT and VT. On the other hand, in spite of non-detectable statistical differences, the exercise intensities associated to the occurrence of the HRVT-SD1 trend to be slightly lower than LT and VT for both T2D and ND, but without statistical difference (p > 0.05). Similarly to our findings, Shibata et al [42] observed that HR corresponding to the HRVT was lower than VT, and the authors suggested that vagal withdrawal would precede the VT occurrence during IT. It is expected that mechanisms responsible for homeostasis during exercise may be related to the occurrence of both VT and LT, and is also dependent to the sympathetic/parasympathetic balance.…”

Cardiac Autonomic Responses during Exercise and Post-exercise Recovery Using Heart Rate Variability and Systolic Time Intervals—A Review

“…Several studies have investigated HRV during exercise (Bernardi et al, 1990; Perini et al, 1990, 2000; Yamamoto et al, 1991, 1992; Dixon et al, 1992; Radaelli et al, 1996; Tulppo et al, 1996, 1998, 1999; Shibata et al, 2002; Casties et al, 2006; Cottin et al, 2006, 2007; Karapetian et al, 2008; Kaikkonen et al, 2010). However, in addition to widely varying HRV analysis methodologies amongst the HRV literature, studies employing exercise with HRV measurements also vary markedly in terms of the participants and exercise protocol.…”

Electrophysiology and kinesiology for health and disease

“…We have recently developed a new exercise prescription method based upon cardiac parasympathetic activity [63,64]. To further verify the validity of this new method, we examined the acute effects of aerobic exercise upon sympatho-vagal activities, b-endorphin, atrial and brain natriuretic peptides (ANP and BNP), and EEG.…”