Are pulses racing fast enough?

February focuses the mind on matters of the heart in many western societies. In 2024 the colorectal community may be forgiven for being more confused than ever before on this topic, not because of St Valentine but more because of the wealth of seemingly contradictory data regarding cardiac health (and especially cardiorespiratory fitness) and colorectal surgery. We have long known that some patients are clearly not fit enough for major colorectal resectional surgery and are best managed by alternative strategies. The past two decades, however, have seen an explosion of research regarding the optimisation of those patients with suboptimal fitness. The correlation between some physiological parameters such as anaerobic threshold (AT) and VO2 Max, and poor outcomes are well established from observational studies [1]. By extrapolation many have sought to mitigate perioperative risk by using exercise programmes to improve these physiologic variables. Intuitively, this seems a common-sense approach and the articles that extol the virtues of preoperative exercise regimes are legion but may not be of the optimal design to establish proof of benefit and causality. Recently, we have seen a long overdue appraisal of the higher quality evidence from the randomised controlled trials that exist regarding prehabilitation, especially relating to cancer surgery. Firstly, RCTs that investigate the role of prehabilitation displayed considerable heterogeneity in outcome reporting, and low outcome reporting quality [2]. A range of endpoints had been used, including patient-reported outcomes, surgical outcomes, physical/functional outcomes, disease activity, and intervention delivery (a process measure rather than an outcome). A core outcome & measurement set is desperately needed in this field and hopefully the Defining Standards in Colorectal Optimisation (DiSCO) Study will report soon [3]. Secondly, the design and conduct of the available RCTs has been called into question [4]. The trials have sample sizes that vary by over an order of magnitude and relatively low rates of recruitment compared to the number screened, which raises concerns regarding external validity and applicability. Several attempts have been made to synthesise the available evidence on prehabilitation. While high profile headlines in the lay press may make one think that this is a cut and dried issue, there remains a considerable degree of circumspection on the part of experts. The reviews were disparate on whether prehabilitation improves functional capacity (e.g. measured by the 6 min walk test), but all were concordant that prehabilitation did not significantly affect postoperative complications, LOS, readmissions etc due to the evidence ranging from moderate to very low quality [5-7]. Whether prehabilitation could be recommended remains a moot point after these excellent attempts at evidence synthesis. Sadly, the situation is no clearer after the recent publication of two large, well conducted trials that have conflicting outcomes. [8, 9] This may in part relate to different patient inclusion criteria, differences in how the intervention is delivered (home/community vs hospital) and exactly what the intervention is (standard exercise regimes or high intensity interval training). There are further studies either in process or write up that may shed light on this topic [10]. Another aspect to the circumspection regarding the utility of such programmes remains scepticism regarding their utility in the short time frames between diagnosis and surgery in those being treated on cancer pathways. While fitness may be able to be optimised over months the time frames for cancer surgery may be too small for any meaningful impact to occur. The converse view is that the intervention is very safe, and the risks of harms are miniscule. In such circumstances, what harms can occur from recommending exercise programmes? A rhetorical question from an individual patient perspective, but from a health service funders perspective the opportunity cost needs to be weighed carefully.