Patients who walk more than 7,500 steps a day prior to surgery have a 51 per cent lower risk of developing post-operative complications, regardless of the complexity of the operation or their health status, new research has suggested.

A study by US researchers described as the first to explore links between physical activity measured through wearable smart watch-like devices and 90-day post-operative complications has found fewer daily steps associated with higher post-operative complication rates.

The findings based on a sample of 475 people have bolstered evidence for the idea that people who keep themselves fit through adequate physical activity are at lower risk of post-operative complications. Earlier studies have indicated that post-surgery complications can occur in up to 30 per cent of patients and about half of such complications occur after patients leave the hospital.

“Our fitness data wasn’t limited to the immediate pre-operative period. The length of the activity record could be six months or several years before surgery,” said Carson Gehl, the study’s lead author at the Medical College of Wisconsin in Milwaukee. “This was more reflective of long-term physical activity habits, versus physical activity in the immediate preoperative period.”

The findings, released on Friday at the annual clinical conference of the American College of Surgeons, raise the question of whether it would be possible for some patients preparing for planned surgeries to lower their risk of post-operative complications through physical activity during the preoperative period. “We need more studies and evidence to answer that question,” Gehl said.

The study documented a complication in about 12 per cent of study participants within 90 days of the surgery. After adjusting for underlying health disorders, age, body weight, sex and the complexity of the operation, the odds of experiencing a complication were 51 per cent lower if patients’ wearable devices showed they had walked more than 7,500 steps per day before the surgery.

Gehl and his colleagues analysed data from electronic health records and wearable devices and the rates of complications in the sample of patients who had undergone a range of operations including general surgery, orthopaedic surgery, and neurosurgery.

Earlier studies have indicated that for certain types of surgeries, obese patients are at greater risk of complications than non-obese patients. A medical team at the University Hospital of Leipzig, Germany, had last year reported higher rates of pneumonia, kidney and liver complications in obese patients undergoing high-risk abdominal surgeries. They analysed data from 886 patients.

However, doctors at the Erasmus Medical Centre in the Netherlands had eight years ago questioned the premise that obesity increases post-operative mortality rates. Their analysis of data from around 4,000 patients had suggested that while obesity is a significant risk factor for wound infection, more surgical blood loss and a longer operation time, being obese is actually associated with improved long-term survival. The Erasmus doctors, writing in the journal BMC Anaesthesiology, had said their findings validate the “obesity paradox”.