Figure 1.

Schematic representation of different trajectories of ageing. The green line indicates a good trajectory for normative ageing. The red line indicates a poorer ageing trajectory, associated with a steeper decline in age-related physiological functional capacity. Loss of functional capacity results in fitness decline, frailty, and a greater risk of mortality. Improving the human health span would require interventions that are capable of pushing the poorer trajectory of ageing up and to the right, providing more years of good health and vitality.