The Benefits of Working Hard in the Gym

High-intensity exercise improved blood sugar control in adults with abdominal obesity more than low-intensity exercise, but both types reduced waist size

(RxWiki News) Exercise is almost never a bad thing, but new evidence suggests that not all exercise is created equal.

New research found that higher-intensity workouts had more health benefits for adults with abdominal obesity than low-intensity routines. Increasing workout intensity decreased abdominal girth and helped lower blood sugar levels.

Exercising at a lower intensity helped decrease tummy size but didn’t appear to affect blood sugar, this study found.

Aaron Michelfelder, MD, professor, vice chair and director of medical student education at Loyola University Chicago Stritch School of Medicine, told dailyRx News that, along with exercise, patients usually need to make diet changes to lose weight.

"What is missing from the study is dietary changes," Dr. Michelfelder said. "Physicians never recommend exercise only for weight loss and would always combine exercise with dietary changes."

Dr. Michelfelder added, "Getting in exercise is important and helpful in any form, but exercise alone is not enough. The mainstay of weight loss and glucose control are dietary changes above all, add exercise for improved effect!"

Lead study author Robert Ross, PhD, of the School of Kinesiology and Health Studies at Queen's University in Kingston, Ontario, said in a press release that "Higher intensity can be achieved simply by increasing the incline while walking on a treadmill or walking at a brisker pace. Participants were surprised by how easy it was for them to attain a high intensity exercise level."

Obesity increases the risk of diseases like heart disease and type 2 diabetes. Type 2 diabetes occurs when people become resistant to insulin, the hormone that regulates blood sugar.

Dr. Ross and team found that people who carried a lot of weight around the middle were at greater risk than others who were obese but carried the weight in other places.

Past research has found that exercise may help people lose weight and improve blood sugar control. However, the current study was designed to demonstrate whether increasing the intensity of regular workouts or the amount of exercise would show the same benefits.

Dr. Ross and team assigned 300 patients to three groups.

The first group performed short, high-intensity workouts, while the second performed long, lower-intensity workouts. Each group exercised five times a week.

Dr. Ross and team determined intensity of exercise using the patients’ heart rate and other measures. The third group did not follow an exercise program.

The study patients were instructed to eat a healthy diet but not to cut calories.

After 24 weeks, patients in both exercise groups had lost slightly more than 1.75 inches around their waists on average.

However, only those in the high-intensity group showed a difference in blood sugar control. Blood glucose levels dropped by an average of 9 percent in this group.

Patients who exercised more intensely and longer also had a greater improvement in their heart and lung function than those in the low-intensity group. This improvement was significant — the low-intensity group had double the risk of dying of heart disease compared to the high-intensity group.

In an editorial about this study, Mihoko Yoshino, MD, PhD, and Samuel Klein, MD, of the Washington University School of Medicine in St. Louis, wrote that “These data provide direct evidence to support the current national guidelines for physical activity and show that even the lowest dose recommended (150 minutes of weekly low-intensity exercise) has healthful effects in adults with abdominal obesity. However, this amount of activity (energy expended during exercise) did not improve [blood sugar] control ... Thus, higher-intensity exercise is better than lower-intensity exercise at any given amount of activity.”

The study and editorial were published March 2 in the Annals of Internal Medicine.

The Canadian Institutes of Health Research funded this study. Dr. Ross and team disclosed no conflicts of interest.

Review Date: 
March 2, 2015