Preparing to have even minor surgery can be daunting, as it brings added stress to what is likely an already full plate of responsibilities. The last thing one might want to think about leading up to surgery is getting enough exercise, but a new study from researchers at the University of Otago in Dunedin, New Zealand, suggests that a short period of high-intensity interval training (HIIT) four to six weeks before having surgery can significantly help with recovery post-surgery.

In fact, researchers found that pre-operative exercise was correlated with a 56% drop in post-operative complications and shorter stays in the hospital.

Fewer Complications and Shorter Stays

The study, published in the journal Surgery, reviewed and analyzed 12 studies that included 832 patients who had undertaken preoperative high-intensity interval training, which involves repeated aerobic high-intensity intervals at about 80% of the maximum heart rate followed by active recovery.

Lead investigator Kari Clifford, PhD, says the study included all types of major surgeries, such as those expected to last more than two hours or with an anticipated blood loss of greater than 500 mL, and included liver, lung, colorectal, urologic and mixed major abdominal surgeries. The average age of participants was 66 years in the intervention group and 67 years in the control group.

“We have found that high-intensity interval training is safe and effective for surgical patients,” says Dr. Clifford. “A HIIT program can meaningfully improve a patient's fitness within four to six weeks, and this reduces postoperative complications and length of stay.”

The most significant result was the change in cardiorespiratory fitness, as determined by measuring VO₂max. This is a measure of how well the body takes in oxygen and delivers it to the muscles and organs during prolonged periods of exercise.

“The pooled results suggest that HIIT increases cardiorespiratory fitness by 2.39 mL/kg/min,” says Dr. Clifford. “This is not only significantly different than standard surgical care but is also clinically relevant. We know that this level of increase is associated with a lower risk of adverse postoperative outcomes.”

Generally, postoperative complications occur in about 30% of patients, or up to 50% for frail patients. In the study, those who undertook HIIT prior to surgery showed a consistent reduction in post-surgery complications, such as cardiac complications, pneumonia and postoperative bowel issues, she says.

“Our study’s pooled results showed that HIIT reduces the risk of having a complication by 56%, which is substantial,” explains Dr. Clifford She adds that, on average, these individuals also stayed for three fewer days in hospital.

What the Research Means to Health and Exercise Professionals

“All of these findings suggest that a period—even as brief as four weeks—of pre-surgery high-intensity interval training may substantially improve patient outcomes and bring with it robust benefits across patient populations,” says Dr. Clifford.

In other words, you can play a role in helping clients prepare for surgery by designing safe and effective programs that incorporate HIIT. When utilizing HIIT with new or deconditioned clients, start with relatively short intervals (10 to 30 seconds) of high-intensity exercise at approximately 85 to 95% of age-predicted max heart rate, followed by longer periods of lower-intensity activity (60 to 70% of maximum heart rate), using relatively stable equipment such as the cycling ergometer with arm action or a rowing machine. Whether they are long-time exercisers or relative newcomers to physical activity, clients of all ages should be able to tolerate one or two high-intensity intervals, followed by active recovery intervals, before gradually progressing to performing more work intervals with shorter periods of active recovery. 

Dr. Clifford offers this reminder, which underscores the wide-ranging benefits of cardiorespiratory fitness: “It is never too late to improve fitness, and this can really make a difference to health outcomes in the surgical context.”