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J. Drouin1, M. Murley2, S. Dadoush3, K. Kearfott3, J. Sharrad3, M. Weinberg3, C.R. Marks4
1Self-employed, Clarkston, Michigan, United States, 2Premier Rehabilitation, Physical Therapy, Holt, Michigan, United States, 3Oakland University, Physical Therapy, Rochester, Michigan, United States, 4Oakland University, Exercise Science, Rochester, Michigan, United States
Background: Heart Rate Variability (HRV) represents the variation between peak to peak heart beats on a 5-minute ECG and it is a sensitive measure of cardiovascular disease (CVD) risk. However, differences in HRV between college-aged women who perform resistance exercise compared to aerobic exercise or who remain sedentary are not known.
Purpose: This study measured HRV differences between sedentary (SED), aerobic (AE) and anaerobic (AN) trained women to determine cardiovascular health and predict CVD risk.
Methods: Following institutional review board approvals, a convenience sample of 18 college aged females (18-35) years) were recruited to participate in this study. Inclusion criteria were women who trained either AE or AN and women who were sedentary. Women who performed a combination of exercises were excluded from the study. Participants did not to eat after midnight or exercise the day prior to testing. Data was collected in the morning using Biopac MP-150 software, an ECG and a metabolic cart (ICC reliability > .96). Participants rested for 10 minutes in a quiet, dimly lit laboratory then two 5-min ECG recordings were taken. Breath rates were standardized at 12 breaths per minute using a metronome for consistency. Data collection was repeated within 10 days and the resulting four 5-min ECGs were averaged for accuracy. The Minimal Clinically Important Difference (MCID) was 3 ms. and CVD risk was determined by Hillebrand ‘s method (2013) where each 1 ms. below 50 ms. equated to a 1% increase in CVD risk; conversely each 1 ms. above 50 ms. represented a 1% lower CVD risk.
Results: HRV measures from 7 AE women were 84.3 ms. and 80.7 ms. from 7 AN trained-women. These measures represented reductions in CVD risk of 30.7 – 34.4%. The measures were also 15.6 – 19.2% higher than age predicted norms of 65.09 ms. HRV measures from 6 SED women were 54.9 ms. which represented only a 4.9% decrease in CVD risk and were also 10.2% lower than predicted for their age.
Conclusion(s): This study found HRV measures from AE and AN trained-women were significantly higher than predicted for their age. Since HRV measures decline 3 ms per decade, these subjects would continue to have measures of 25 – 35-year old women into their 70-80 year-age range. However, SED women had HRV measures significantly lower than predicted for their age and their values were like 55 – 65-year-old women. Moving forward in time, SED women would begin to experience increased CVD risk and ANS dysfunction in the 35 – 45 year-age range when their HRV measures would be those of 65-74 year old women.
Implications: The outcomes of this study provide support for physical therapists on the importance of engaging in health promotion that includes AE and AN exercise among college aged women to promote health, prevent cardiovascular disease (CVD) and improve ANS balance.
Funding, acknowledgements: Oakland University Provost's Graduate Student Research Grant
Keywords: Heart Rate Variability, Cardiovascular Disease Risk, College Aged Women
Topic: Cardiorespiratory
Did this work require ethics approval? Yes
Institution: Oakland University, Rochester, Michigan USA
Committee: Institutional Review Board
Ethics number: 741106-1
All authors, affiliations and abstracts have been published as submitted.
