Is harder always better when it comes to working out?

SEATTLE - For many Americans short on time, quicker, high-intensity workouts may seem ideal. But, local doctors say those hard workouts are not sustainable for most people and can even be hazardous to their health.

For experienced athletes looking to get better at their sport, high-intensity interval training is appropriate, said Dr. Chris Maeda, a sports medicine specialist at Pacific Medical Centers. But, he said intense exercise is not feasible for the majority of people who are not exercising on a regular basis.

"You have to work your way up slowly to get there," Maeda said. "High-intensity exercise should only be for people that already work out. You don't go from the couch to a sprint unless you're looking to hurt yourself."

High-intensity training can have serious health consequences, according to Dr. Sarah Speck, a cardiologist at Swedish Medical Center. These workouts can lead to rhabdomyolysis - the breakdown of skeletal muscles - as well as kidney failure, inflammation and injury.

"You really need to be trained to be working at those high intensities," she said.

In addition, because high-intensity training is so uncomfortable, many will not stick with it, Maeda said.

"If you want the same benefits in less time you have to work harder, which most people are not willing to do," he said.

Speck said people experience greater health benefits from moderate exercise and movement spread throughout the day. Our bodies are designed for constant motion, she said, but today's lifestyles don't accommodate that.

"Physically, we want to keep moving," Speck said. "We want to use the fuel we give our bodies as nutrition to do activities."

She says spending more time being active - even at a lower intensity level - is better for cardiovascular health and burns more fat.

"When you get into intense exercise you miss those long term benefits," Speck said. "You may lose weight, but unless you're truly conditioned in both higher and lower intensity you're losing the health benefits of moderate exercise."

While there are weight-loss benefits to high-intensity workouts, Maeda said for those aiming to burn calories, the time you dedicate to exercise may be more important than the intensity level. For example, he said a golfer walking four miles on the course in five hours will burn more calories than a 5K runner going 3.1 miles in 30 minutes.

"Your runner will probably be in better shape because it is more intense, but the golfer will burn more calories because they are out there longer," Maeda said.

Dr. Mollie Grow, a pediatrician at Seattle Children's Hospital, says people who spread out moderate exercise throughout each day are likely to sustain a healthy lifestyle.

"We need to have a balanced view of the average person," Grow said. "Lifestyle exercise is the thing that works the best for me - walks to the bus or bike rides with my daughter."

Maeda said no matter what the intensity, the most sustainable form of exercise is one you look forward to.

"You're going to do whatever you don't dread. Go for walks, bike, garden - anything you enjoy! Something is better than nothing."