Two Northern Arizona University faculty members have been collaborating with cardiologists at the University of Arizona's Sarver Heart Center.  These researchers are studying the effects of an exercise machine they developed at NAU that could help frail seniors double their muscle strength without the effort of aerobic exercise or weightlifting.

The machine looks like a recumbent exercise bicycle, but instead of having pedals that rotate forward, it uses a motor to drive the pedals backward. The rider tries to slow their movement, via eccentric (or negative) muscle work, by pressing against the pedals, which causes the muscle to act as a brake, such as when a person hikes downhill.

Stan Lindstedt, PhD, a regents professor in biology at NAU and Paul LaStayo, PhD, PT, an assistant professor of physical therapy from NAU, have spent the past 6 months studying the bike's effects on elderly individuals (average age is 81), who suffer from muscle wasting, have cardio-respiratory limitations and are at a high-risk for falling. Drs. LaStayo and Lindstedt are using the bike in a pilot study to see whether it could benefit people with sarcopenia, the muscle wasting that occurs with age. Each of the elderly participants have been using the bike for 10-20 minutes three times a week. The study is funded by the National Institute on Aging, one of the 25 institutes and centers of the National Institutes of Health.

The training on this bike is different not only in how the pedals move, but in the physiological responses. "The activity feels like it's very low intensity," says Dr. Lindstedt.  "There is minimal or no increase in heart rate when they're on the bike, and minimal or no increase in respiratory rate."

Despite the low-intensity nature of the training paradigm there are profound muscle changes that occur. Because the bike works the leg muscles without making the rider tired or winded, the activity more closely resembles weightlifting than aerobic exercise, but requires far less effort. "There's something about this kind of eccentric lengthening muscle contraction that allows very high muscle forces with very low energy," Dr. LaStayo says. "It's not 100 percent clear why that's the case."

Drs. Lindstedt and LaStayo report that after eight weeks of training (the study is 10 weeks long), all of the participants have increased their workloads on the bike 10 fold and more than doubled the muscle strength in their legs,. "It is evident that even octogenariens with moderate cardio--respiratory impairment respond to this training paradigm just like young healthy college-aged individuals. That is, they adapt very quickly to the high muscle loads, have minimal perceived exertion and they get stronger" Dr. LaStayo says.

"There are a lot of individuals who are exercise intolerant because of heart or respiratory problems," Dr. Lindstedt says. When that happens, it's a downward spiral because the person loses muscle mass and strength and becomes progressively weaker, resulting in falls and broken bones.

Dr. LaStayo and Dr. Lindstedt hope the results from the pilot study will lead to a larger grant that would allow them to return to the Heart Center to study the bike's benefits for people with chronic heart failure or chronic obstructive pulmonary disease, such as emphysema. If further studies validate the bike's apparent benefits, Drs.  Lindstedt and LaStayo think it eventually could be used to help people suffering from severe heart or respiratory problems or who are recovering from heart transplants or heart attacks. The bike could work as a bridge back to typical exercise routines thus helping elderly individuals at least maintain their muscle mass until they can resume normal activities. There is even some evidence that it may improve bone density. "And because it's takes little energy to use, Dr. Lindstedt notes, it's more likely they would stick with it."