Heart rate variability, but not heart rate, is associated with handgrip strength and mortality in older Africans at very low cardiovascular risk: A population-based study. (6th May 2015) - Koopman, Jacob J.E.; van Bodegom, David; Maan, Arie C.; Li, Zhao; Ziem, Juventus B.; Westendorp, Rudi G.J.; Jukema, J. Wouter