title: Systematic review: the impact of exercise on mesenteric blood flow and its implication for preoperative rehabilitation.
abstract: BACKGROUND
  Exercise in the preoperative period, or prehabilitation, continues to evolve as an important tool in optimising patients awaiting major intra-abdominal surgery. It has been shown to reduce rates of post-operative morbidity and length of hospital stay. The mechanism by which this is achieved remains poorly understood. Adaptations in mesenteric flow in response to exercise may play a role in improving post-operative recovery by reducing rates of ileus and anastomotic leak.
  
  
  OBJECTIVE
  To systematically review the existing literature to clarify the impact of exercise on mesenteric arterial blood flow using Doppler ultrasound.
  
  
  METHODS
  PubMed, EMBASE and the Cochrane library were systematically searched to identify clinical trials using Doppler ultrasound to investigate the effect of exercise on flow through the superior mesenteric artery (SMA). Data were extracted including participant characteristics, frequency, intensity, timing and type of exercise and the effect on SMA flow. The quality of each study was assessed using the Downs and Black checklist.
  
  
  RESULTS
  Sixteen studies, comprising 305 participants in total, were included. Methodological quality was generally poor. Healthy volunteers were used in twelve studies. SMA flow was found to be reduced in response to exercise in twelve studies, increased in one and unchanged in two studies. Clinical heterogeneity precluded a meta-analysis.
  
  
  CONCLUSIONS
  The weight of evidence suggests that superior mesenteric arterial flow is reduced immediately following exercise. Differences in frequency, intensity, timing and type of exercise make a consensus difficult. Further studies are warranted to provide a definitive understanding of the impact of exercise on mesenteric flow.
authors.affiliation: Department of Surgery, Queen Elizabeth University Hospital, 1345 Govan Road, Glasgow, G51 4TF, UK.
authors.forename: K A
authors.initials: KA
authors.lastname: Knight
authors.affiliation: Department of Surgery, Royal Alexandra Hospital NHS Trust, Corsebar Road, Paisley, PA2 2PN, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Moug
authors.affiliation: Academic Unit of Cancer Sciences, Faculty of Medicine, University of Southampton, South Block, Mail Point 816, Southampton University Hospital, Southampton, SO16 6YD, UK. M.West@soton.ac.uk.
authors.forename: M A
authors.initials: MA
authors.lastname: West
mesh_terms: D000005:Abdomen / Q000601:surgery; D000328:Adult; D000368:Aged; D057868:Anastomotic Leak / Q000209:etiology / Q000517:prevention & control; D002986:Clinical Trials as Topic; D013505:Digestive System Surgical Procedures / Q000379:methods / Q000534:rehabilitation*; D015150:Echocardiography, Doppler / Q000379:methods; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D045823:Ileus / Q000209:etiology / Q000517:prevention & control; D008297:Male; D008638:Mesenteric Arteries / Q000000981:diagnostic imaging* / Q000502:physiology; D008875:Middle Aged; D057234:Preoperative Period; D013152:Splanchnic Circulation / Q000502:physiology*; D016896:Treatment Outcome; D055815:Young Adult
keywords: Cancer; Colorectal; Mesenteric blood flow; Prehabilitation