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Purpose: The dynamics of vagal withdrawal and reactivation during pulses of exercise are described by indices computed from heart period (RR) variations, which may be sensitive to duration and load. We sought to assess the consistency over time of these indices, which is not well established., Methods: We recorded continuous electrocardiogram during series of five successive bouts (2 min) of submaximal exercise (at 40 and 70% of VO(2peak), different days). Autonomic responsiveness was inferred from quantification of onset and offset of RR dynamics of each individual bout. Consistency of results was assessed with intraclass correlation (ICC)., Results: During exercise bouts, indices from tachycardic and bradycardic transients reach lower levels in response to higher exercise loads and progression of exercise. There is a significant effect of load and time (i.e., bout repetition) for all examined variables, with a clear interaction. However, no interaction is observed with the 60 s change in heart rate. ICC analysis demonstrates that various indices are characterized by large differences in stability, which is generally greater within the same day (e.g., tachyspeed ICC at 40% = 0.751, at 70% = 0.704, both days = 0.633; bradyspeed, respectively, = 0.545, 0.666, 0.516)., Conclusions: Intensity and duration of exercise modulate vagal withdrawal and reactivation. Analysis of RR variations, during successive brief exercise bouts at lower and higher intensity, ensures a consistency similar to that reported for autonomic cardiac regulation at rest and might guide the choice among multiple indices that are obtained from the tachogram.

Purpose: Autonomic assessment might be useful in training management. We planned to assess whether oscillatory metrics of RR variability (such as LFnu) would be more efficient than static indices from low order statistics (RR variance) at discriminating laying rest from stand posture, as an analog of a shift to sympathetic dominance.Methods: We studied a large population of elite Olympic athletes: a total of 406 athletes (162 females and 244 males, of similar age 21.7 and 24.4 years) participating to the selection for the upcoming 2016 Olympic games. We employed various methods to extract autonomic indices from RR variability and employed a stepwise statistical approach combining factor and discriminant analysis.Results: We observed that that relative power of oscillatory components from spectral analysis of RR variability (such as LF or HF in nu) and indices from symbolic analysis (particularly 0V) clearly outperform RR variance in discriminating between two physiological conditions (laying rest and stand) related to posture and autonomic activation.Conclusions: In world class Olympic athletes we have shown that a small subset of RR variability indices, related to sympathovagal balance, may be more appropriate than RR variance to assess excitatory sympathetic autonomic responsiveness of the SA node. These findings may have practical implications for the use of RR variability in guiding training and predicting success in competitions. [ABSTRACT FROM AUTHOR]

Background Chronic non-communicable diseases represent the major drivers of disease burden, being responsible for the majority of health care cost and deaths. Almost half of premature deaths is due to behaviors amenable to change. Accordingly, addressing behavior might represent a strategic change in the health delivery system. Improving lifestyle requires a specific strategy embedding the active collaboration of individuals with a multilevel team-oriented medical practice. With the present study we sought to assess whether the implementation of cognitive-behavioral strategies, following the principles of lifestyle medicine in an outpatient clinic provides better results in weight reduction as compared to simpler strategies as presently executed in General Practitioners' offices. Methods This is an observational study on 173 subjects (age 53.1 ± 11.5), comparing three different groups of preventive practice: a personalized lifestyle medicine, combining cognitive behavioral strategies with patient tailored prescription of exercise and nutrition (Group A); a semi-structured approach with generic counseling (Group B); and an unstructured advice (Group C). Results At the end of the intervention period (17–20 months), group A showed an average weight loss of 5.4 ± 5.1 kg, which was significantly (p < 0.001)more than observed in group B (2.8 ± 5.1 kg) and group C (1.2 ± 4.8 kg). Likewise BMI and waist were progressively more reduced from A to C. Conclusions It is possible to implement preventive cognitive-behavioral lifestyle strategies in outpatient internal medicine clinics. This methodology appears more efficacious in inducing weight reduction after more than a year as compared to usual family medicine approaches. [ABSTRACT FROM AUTHOR]