Sex Differences in Cardiac Autonomic Modulation and Baroreflex Sensitivity Following Differential Exercise Training

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Ashley Noel Lightner (Creator)
Institution
Appalachian State University (ASU )
Web Site: http://www.library.appstate.edu/
Advisor
Scott Collier

Abstract: Maintained balance between sympathetic and parasympathetic tone within the cardiac autonomic systems is a vital component of cardiovascular regulation. The alteration of baroreflex function can contribute to chronic parasympathetic withdrawal and subsequent sympathetic dominance that is often seen in the development and progression of cardiovascular diseases. Heart rate variability (HRV) and baroreflex sensitivity (BRS) are non-invasive clinical measures utilized to assess baroreflex control and cardiac autonomic modulation, respectively. Aerobic exercise (AE) training has been shown to increase HRV and BRS; however, little is known concerning the response of HRV or baroreflex function to resistance exercise (RE) training. The purpose of this study was to assess the potential sex differences of short-term aerobic training versus resistance training on HRV and BRS in a hypertensive population. A 2x2x2 design was utilized to analyze mode (resistance vs. aerobic) x time (pre- versus post-training) x sex (male versus female). Forty pre- to stage-1 essential hypertensives between the ages of 33 and 60 years old (20 men, 20 women) underwent either AE training [30 minutes of treadmill exercise, 3 days per week at 65% of peak oxygen consumption (VO2 peak)] or RE training (3 sets of 10 repetitions for 9 major muscle groups, 3 days per week at 10 repetition maximum). Body mass index (BMI), body composition assessment, electrocardiogram (ECG) recordings, beat-to-beat blood pressure (BP), and heads up tilt tests were performed at baseline pre and post 4 week training period. An increase in BRS was seen in both sexes following AE training; however, RE training, showed decreases in BRS in males and no change in females. Following RE training decreases in HRV as indicated by the low frequency to high frequency (LF: HF) ratio were seen in males, and increases in HRV were observed within females. These data show that 4 weeks of moderate intensity aerobic training results in increases in BRS and HRV in both sexes. The decrease in BRS seen in males following 4 weeks of RE training may be related to an increase in arterial stiffness in hypertensive individuals.

Additional Information

Publication
Thesis
Lightner, A.N. (2011). Sex Differences in Cardiac Autonomic Modulation and Baroreflex Sensitivity Following Differential Exercise Training. Unpublished master’s thesis. Appalachian State University, Boone, NC.
Language: English
Date: 2011