Fisiologia umana I - regolazione nervosa del cuore

OF TREADMILL EXERCISE IN HEALTHY YOUNGSUBJECTS

Cibelli et al., 2008© G. Cibelli, 2008 58° Congresso SIF - 2007 14

Background

• The autonomic nervous system plays a substantial role in the physiological adaptation of cardiovascular functions to change during physical exercise
• In normal subjects exercise is associated with an augmentation of sympathetic tone, whereas vagal tone is high during resting conditions
• The concept of sympathovagal balance has arisen to characterize the autonomic state resulting from these sympathetic and vagal influences
• Heart rate variability (HRV) analysis has emerged as a prevalent technique to assess autonomic influences on the heart
• A number of stress markers, such as corrtisol and catecholamines, have been found to reliably indicate reactivity of physiological stress systems, e.g. the hypothalamic-pituitary-adrenal (HPA) axis

thesympathetic nervous system (SNS) to exercise. Salivary a-amylasehas been suggested to reflect catecholaminergic reactivity to exercisechallange© G. Cibelli, 2008 58° Congresso SIF - 2007

Aim of the study

• To test the effects of treadmill exercise onsalivary a-amylase and cortisol levels, as wellas on cardiovascular parameters, e. g. heartrate (HR), blood pressure (BP) and HRV, inhealthy young subjects
• To find out possible correlations betweenindices of sympathovagal balance and salivarybiomarkers© G. Cibelli, 2008 58° Congresso SIF - 2007

Subjects and protocol

• Twentyfour healthy volunteers participated to this study
• After 6 minutes rest assessment, in upright position, each subject saton a treadmill ergometer (E-motion MTC Climb, Runner, Italy) andperformed an exercise test achieving 92±3% (submaximal level) ofthe theoretical maximal heart reserve (computed as 220 – subject’sage in years), using the Bruce protocol.

1. The LF (low frequencies, 0.04 to 0.15 Hz) and high frequencies (HF, 0.15 to 0.4 Hz) bands was expressed in ms².
2. The LF/HF ratio was calculated from these values and normalized LF (nLF) and HF (nHF) powers were calculated by dividing the individual values by the total power, using the Acqknowledge version 3.9.2-100 M. © G. Cibelli, 2008 58° Congresso SIF - 2007 19
3. Descriptive statistics for the anthropometric characteristics. © G. Cibelli, 2008 58° Congresso SIF - 2007 20
4. The physiological measures at peak treadmill exercise. © G. Cibelli, 2008 58° Congresso SIF - 2007 21
5. Spectral analysis of HRV. © G. Cibelli, 2008 58° Congresso SIF - 2007 22
6. The effects of treadmill exercise on cardiovascular variables. © G. Cibelli, 2008 58° Congresso SIF - 2007 23
7. The effects of treadmill exercise on HRV indices. © G. Cibelli, 2008 58° Congresso SIF - 2007 24