Comparative Study

Loss of lag-response curvilinearity of indices of heart rate variability in congestive heart failure.

Bmc Cardiovasc Disor. 2006 Jan 1;6:27.
Article

Time domain, geometrical and frequency domain analysis of cardiac vagal outflow: effects of various respiratory patterns.

Clin Physiol. 2001 May 1;21(3):365-76.
Randomized Controlled Trial

Heart rate variability as a predictor of negative mood symptoms induced by exercise withdrawal.

Med Sci Sports Exerc. 2007 Apr 1;39(4):735-41.