Author(s): MALMGREN, A., TRÄGÅRDH, E., GUDMUNDSSON, P., STAGMO, M., DENCKER, M., Institution: SKÅNE UNIVERSITY HOSPITAL, Country: SWEDEN, Abstract-ID: 879

INTRODUCTION:
Long-term intense training leads to structural, functional, and electrical remodelling of the heart which may overlap with cardiac pathology. Cardiac abnormalities can be identified using a 12-lead resting electrocardiogram (ECG), by careful interpretation, to differentiate physiologic cardiac adaptations from underlying pathology. Heart rate variability (HRV) is a non-invasive marker of cardiac autonomic function and has been associated with cardiovascular health and physical fitness. Although regular physical activity is known to improve autonomic function, sex-specific data on ECG findings and HRV responses to regular exercise in women remain limited. The aim of this study was to compare ECG and HRV parameters between physically active middle-aged women and age-matched women who do not engage in regular structured exercise.
METHODS:
In this cross-sectional study 38 endurance trained women and 36 inactive women underwent a 12-lead resting ECG and a 48-hours ambulatory ECG. Left ventricular dimensions included the sum of QRS voltage in all 12-leads (from the peak of the R wave to the nadir of either the Q wave or the S wave, whichever was deeper), Cornell voltage, Sokolow & Lyon and a voltage-duration product for each of the three measurements was calculated by multiplying the voltage criterion by QRS duration. HRV was recorded using 48-hours ambulatory ECG. Inter-group differences were evaluated using the Independent-samples t-test and a p-value <0.05 was considered statistically significant.
RESULTS:
HRV data was missing in one endurance trained women. Sinus bradycardia was found in eight trained women and in three inactive women. Left ventricular hypertrophy (LVH) were found in three inactive women and in two trained women according to the Sokolow & Lyon criteria and in one trained woman according to the Cornell criteria. None of them had findings of hypertension or LVH on echocardiography. 12-lead sum of voltage (p<0.001), Sokolow & Lyon (p<0.001) and their voltage multiplied by QRS (p<0.001 and p=0.001 respectively), all reflecting left ventricular size, showed statistical inter-group differences. This was not seen in Cornell voltage (p=0.211) and its QRS product (p=0.225). During 48-hours of ECG monitoring the physical active women had significantly higher maximal heart rate (p 0.013) and lower average and minimal heart rate (p<0.001) compared to the inactive women. Measures of heart rate variability, including SDNN, RMSSD and pNN50 were all significantly higher in active women (p<0.001).
CONCLUSION:
Engaging in regular physical activity appears to enhance cardiac electrical and autonomic function in middle-aged women, reflected by higher HRV, a well-established indicator of cardiovascular health and general fitness.