Background: In the past, isometric exercises were proscribed for heart disease. However, recent evidence suggests that an isometric handgrip training (IHT) protocol -four sets of two minutes at 30% of maximum strength -produces favorable effects on the autonomic modulation and reduces resting systolic (SBP) and diastolic (DBP) blood pressure.

Cardiac vagal tone (CVT), a key determinant of resting heart rate (HR), is progressively withdrawn with incremental exercise and nearly abolished at maximal effort. While maximal HR decreases with age, there remains a large interindividual variability of results for any given age. In the present study, we hypothesized that CVT does not contribute to age-independent maximal HR. Data were obtained from 1 000 (39±14 years old) healthy subjects (719 men) who were not taking medications affecting CVT or maximal HR performed a clinically normal and truly maximal cardiopulmonary exercise testing. CVT was estimated using the cardiac vagal index (CVI), a dimensionless ratio obtained by dividing 2 cardiac cycle durations--end of exercise and pre-exercise--, reflecting HR increases during a 4-s unloaded cycling test (a vagally-mediated response). Maximal HR was expressed as % of that predicted by age (208-0.7 × age (years)). Linear regression analyses identified that CVI can explain only 1% of the % age-predicted maximal HR variability with a high standard error of estimate (~6.3%), indicating the absence of a true physiological cause-effect relationship. In conclusion, the influence of CVI on % of age-predicted maximal HR is null in healthy subjects, suggesting distinct physiological mechanisms and potential clinical complementary role for these exercise-related variables.

EHRG, a novel index combining HR reserve and HR recovery, is a better indicator of mortality risk than either response alone.

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BackgroundExercise-based cardiac rehabilitation tends to reduce mortality. However, it requires medium/long-term adherence to regular physical exercise. It is relevant to identify the variables that affect adherence to an supervised exercise program (SEP).ObjectiveTo evaluate the influence of pre-participation levels of aerobic and non-aerobic physical fitness components in medium-term adherence to SEP.MethodsA total of 567 SEP participants (65 ± 12 years) (68% men) were studied. Participants adherent to the program for less than 6 months (48%) (non-adherent - NAD) were compared with 52% of participants who were adherent for 6 months or more (adherents - AD). In the non-aerobic fitness, flexibility (FLX) (Flexitest) and muscle power (MPW)/body weight in standing rowing (watts/kg) were evaluated while aerobic fitness was obtained by direct measure of VO2max/body weight (VO2). These measurements were normatized for sex and age based on percentiles (P) (P-FLX/P-MPW) of reference data or percentages of predicted (P-VO2). Additionally, AD and NAD with extreme results (tertiles) were simultaneously compared for the three variables.ResultsThere was no difference between AD and NAD for non-aerobic results, in median [P25-P75], P-FLX: 30 [13-56] and 31 [9-52], respectively, (p = 0.69) and P-MPW: 34 [17-58] and 36 [16-62], respectively (p = 0.96), and for aerobic results (mean ± standard error) P-VO2 (75.9 ± 1.3% and 75.0 ± 1.3%, respectively) (p = 0.83). When comparing extreme tertiles, a difference was found for P-MPW in the lower tertile only, with a slight advantage of AD over NAD- 9 [5-16] versus 4 [1-11] (p = 0.04).ConclusionAlthough awareness of the pre-participation levels of aerobic and non-aerobic physical fitness components is useful for individualized exercise prescription, these variables do not seem to influence medium-term adherence to SEP.

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