Date of Award

Spring 2005

Document Type


Degree Name

Master of Science in Biomedical Engineering - (M.S.)


Biomedical Engineering

First Advisor

Stanley S. Reisman

Second Advisor

Ronald H. Rockland

Third Advisor

Joel Schesser

Fourth Advisor

Sina Zaim


The goal of this thesis is to determine if a relationship exists between the activity of the autonomic nervous system (ANS) and the speed of heart rate recovery post maximal exercise. The parasympathetic branch of the ANS was assessed during rest by obtaining the high frequency (HF) component of the heart rate variability (HRV) frequency spectrum. The recovery time was estimated by fitting an exponential curve to the heart rate post exercise where the exponent was used to calculate the time constant to indicate recovery time. A regression was then performed on the HF and recovery time in order to find a relationship between the ANS activity and the recovery time.

Changes in the ANS through all stages of the experiment were characterized using two different time-frequency methods; Continuous Wavelet Transform (CWT) and the Short Time Fourier Transform (STFT).

A moderate relationship (R2=0.5164) exists between the HF and the rate of recovery. Changes in the ANS throughout the experiment indicated a drop in both the LF and HF (where LF represents a mixture of sympathetic and parasympathetic activity) values during exercise and may indicate sympathetic saturation. The normalized LF and HF values contained a large spike in the LF and a corresponding drop in the HF at the start of exercise and again at the start recovery indicating sympathetic activation and sympathetic desaturation, respectively.