D-25 Free Communication/Poster - Endurance Performance and Training: JUNE 2, 2011 1:00 PM - 6:00 PM: ROOM: Hall B
PURPOSE: The current study address the inconsistencies observed in studies (study protocol, HRV techniques and results produced) on the effect of exercise interventions on the autonomic nervous system as measured by HRV
METHODS: This was a prospective twelve week strictly standardised exercise intervention on recruits (n=185, 100 male and 100 females) from the South African National Defence Force (SANDF). None of the participants were professional athletes or high level sport participants. The study protocol was submitted and approved by the (SANDF) and by the Ethical committee of the University of Pretoria, and all participants gave written consent. All participants were subjected to exactly the same standardised 24 hour routine (exercise, diet and sleep) for the duration of the twelve week exercise intervention. HRV was determined by calculation of HRV indicators with time domain, frequency domain and non-linear analysis. Median values were calculated from 3 separate 180 second tachograms for every participant in the supine (0-180s, 180-360s, 360-540s) and 3 separate tachograms in the standing position (0-180s, 180-360s, 360-540s), measured pre- and post the exercise intervention. The Wilcoxon signed-rank test (95% confidence level), were used to determine the significance of differences between pre and post measurements.
CONCLUSIONS: Novel finding: the current study showed that increased vagal influence on HR is not only visible in the supine position, but also during standing up (a non-stationary period), as well as in the standing position (after stabilisation), as measured HRV indicators from 6 different time periods after a twelve week exercise intervention.