PURPOSE: To verify if athletes submitted to volume overload display differences in the cardiac autonomic function throughout the post-exercise recovery phase comparatively to athletes submitted to resistance overload.
METHODS: 30 men were divided into three equal groups (p>0,05): non-athlete group (n=10 30.8±3.0 year, BMI: 24.6±2.7 kg/m²), high-intensity functional training athletes (n=10, 31.4±2.9 year, BMI: 31.4±2.2 kg/m²), and triathlon athletes (n=10, 31.2±2.8 year, BMI: 23.1±1.8 kg/m²). Participants underwent a maximal graded treadmill exercise test followed by a five-minute of active recovery protocol (2,4km/h 2,5%). During the post-exercise recovery phase, a valid R-R intervals series were recorded (5min) using a valid and reliable heart rate monitor. The data were processed off-line using the Kubios HRV - Heart Rate Variability Software. A Kruskal-Wallis test was used to determine differences in SD1 and SD2 indices between all groups. The SD1 and SD2 indices were used to assess the degree of parasympathetic reactivation and global cardiac modulation, respectively over the recovery phase. Heart rate variability, by means, SD1 and SD2 indexes of Poincaré Plot were recorded during the 30s; 1^stmin; 3^rdmin and 5^thmin of recovery to evaluate the cardiac autonomic function (CAF).
RESULTS: No significant differences were found in parasympathetic and global cardiac modulation between groups, There were no difference between 3 groups in SD1-30s (2.66-3.15; p = 0.29), SD1-1^st min (2.52-3.24; p = 0.23), SD1-3^rd min (2.87-3.72; p = 0.58), SD1-5^th min (3.08-4.29; p = 0.44), SD2-30s (2.22-2.88; p = 0.21), SD2-1^st min (2.57-2.92; p = 0.39), SD2-3^rd min (4.36-5.78; p = 0.58), SD2-5^th min (5.34-6.79; p = 0.53). Possibly, the magnitude of differences is small, which warrants a larger sample size than used in our study to detect statistical differences.
CONCLUSIONS: In our study, no significant differences in parasympathetic and global cardiac modulation were found between groups. These initials results show that individuals submitted to resistance and volume overload training have similar abilities of the autonomic branches (sympathetic and parasympathetic) on the modulation of the heart throughout the post-exercise recovery.