Whilst frailty and ageing are inherently linked, we agree with O' Hanlon and Rechner that frailty is likely to be more useful for assessing perioperative risk in older people . Physical inactivity is a defining feature of frailty, and a target of numerous frailty intervention studies . Health benefits from a physically active lifestyle are well-documented; increased physical activity can delay the onset and slow the progression from a non-frail to frail state . Furthermore, there is growing evidence of the association between physical activity and perioperative outcomes . Such considerations have prompted the incorporation of promotion of activity into prehabilitation in this population. Whilst sustained change in habitual, environmentally-cued behaviours such as physical activity is notoriously difficult to achieve, it is plausible that the preoperative period may represent a “teachable moment” in which motivation may be elevated. However, the impact that increasing preoperative physical activity has on frail elderly patients, the optimal type, duration and intensity of physical activity for prehabilitation programmes and the mutable determinants of activity in this population are poorly understood. Consequently, parameters that are likely to be important in the design and evaluation of complex interventions targeting preoperative physical activity remain uncertain.