Importance of "muscle" and "intestine" training before major HPB surgery: A review.

Major hepato-pancreato-biliary (HPB) surgery is one of the most invasive abdominal surgeries. Through the experiences of several clinical trials, including those involving patients undergoing major HPB surgery, we have recognized the importance of "muscle" and "intestine" training before surgery. This review article summarizes the results of our clinical trials, specifically focusing on the importance of "muscle" and "intestine". The patients with low skeletal muscle mass or those with low functional exercise capacity showed a significantly worse postoperative course and poor long-term survival after surgery for HPB malignancy. The introduction of prehabilitation (preoperative physical and nutritional support) improved nutritional status and functional exercise capacity, even in patients with malignancy. Daily physical activity was correlated with nutritional status before surgery. These results indicated the usefulness of prehabilitation. The intestinal microenvironment, which is extrapolated from the fecal concentrations of short-chain fatty acids (SCFAs), showed a significant association with the incidence of surgery-induced bacterial translocation and postoperative infectious complications (POICs). The use of perioperative synbiotics not only increased the fecal levels of SCFAs but also prevented the incidence of POICs. A recent study also indicated that there are correlations between muscle mass and the intestinal microenvironment. Further investigation is required to determine the best "muscle" and "intestine" training protocol to improve the outcomes of major HPB surgeries.