Conventionally, linear time and spectral domain analysis of heart rate variability (HRV) are identified and corresponded as behavioural and physiological response measures. At rest, for example, the very low frequency (VLF) and low frequency (LF) components estimated from electrocardiogram (ECG) are thought to reflect response to sympathetic input while the high frequency (HF) component is believed to reflect response to vagal activity. This study examines the traditional techniques used to quantify ECG acquired before and after routine daily physiological exercise.