Morbidly obese adults are sedentary for more than 99 percent of the day, getting only a fraction of the amount of walking that experts recommend for staying healthy, a small study suggests.

The study of 10 men and women found that participants spent an average of 23 hours and 52 minutes sleeping, lying down or sitting each day. They typically took about 3,700 steps throughout the day — compared with the 10,000 steps that experts recommend for healthy living.

The findings have important implications for lowering heart disease risk among morbidly obese adults, according to Dr. Thomas Vanhecke and his colleagues at William Beaumont Hospital in Royal Oak, Michigan.

"These results may provide important links between obesity, poor fitness and cardiovascular disease," the researchers report in the journal Clinical Cardiology.

The term morbid obesity is used to describe people whose body mass index (BMI) — a measure of weight in relation to height — is 40 or higher. While severe obesity itself contributes to heart disease, low exercise levels and poor fitness further that risk.

Studies have found that even among obese adults, those with higher fitness levels tend to be healthier. And any regular exercise, including light walking, can boost fitness and have health benefits for the severely overweight, Vanhecke and his colleagues write.

The 10 morbidly obese adults in the current study had an average BMI of 53.6. The researchers had them wear an activity sensor that kept track of their calorie expenditure, minute-by-minute physical activity and number of steps per day over three days. None had heart disease, serious arthritis or other disorders that would limit their mobility.

While the study participants got little physical activity, on average, those who managed to take relatively more steps each day did tend to have higher fitness levels, the researchers found.

The findings, according to Vanhecke's team, "will add incentive to increase physical fitness in this population and increase the awareness of healthcare professionals of the need for recommending physical activity in their patients."