The finding could be a boon to older adults, since age tends to slow down wound healing, raising infection risk, write Charles Emery, PhD, and colleagues.
The results recently appeared in the Journal of Gerontology: Medical Sciences. Here's how the study worked.
Step 1: Get Moving -- or Not
Emery's study included 28 older adults who were 55-75 years old. At the study's start, all participants were sedentary, meaning they hadn't exercised regularly for at least six months.
Half were told to work out three times per week at Ohio State. Here's what each session involved:
- Warm up for 10 minutes with stretches.
- Ride a stationary bike for 30 minutes hard enough to maintain a certain goal heart rate.
- Walk briskly and/or jog for 15 minutes.
- Use exercise equipment to strengthen arm muscles.
- Cool down for five minutes.
The other participants were told to stay sedentary. Both groups were asked not to change their normal diets.
Step 2: Get Wounded
After a month, the researchers gave participants tiny skin wounds in the back of their upper arms. Right-handed participants got the wound in their left arm and vice versa.
The month's delay allowed the exercisers' bodies to adjust to their new routine.
The wounds were immediately bandaged for 24 hours. After that, no bandage was needed.
A week later, the researchers photographed each wound with a high-resolution digital camera. The wounds were photographed three days per week until they had healed and couldn't be seen.
The goal was to see which group healed more quickly. The researchers predicted that the exercisers would win that race.
Step 3: Heal the Wound
None of the wounds had totally healed after two weeks. All had healed within seven weeks. Wounds had healed by four weeks for a significantly greater proportion of exercisers, the study shows.
Participants also took before-and-after fitness tests and stress surveys. In addition, they gave samples of saliva at the start and end of the three-month study. The researchers used the saliva samples to measure cortisol, a stress hormone.
Not surprisingly, fitness improved most for the exercisers. The stress results were a bit more complex.
Stress? What Stress?
Participants' stress ratings didn't change much during the experiment, whether they exercised or not. There hadn't been much room for improvement, since none had reported a lot of stress to start with.
Cortisol levels rose for the exercisers, to the researchers' surprise. They had expected cortisol levels to drop with exercise. Cortisol may have a positive effect on the healing process, write Emery and colleagues.
"The stress of exercise may enhance the regulation of cortisol," Emery says in a news release. "This increase in cortisol levels may represent a biological pathway by which exercise helps wounds heal."
Elders who feel more stress may have different results, and further studies should check that possibility, write the researchers.
The study supports the idea of using exercise as part of medical care for patients recovering from skin wounds or surgery, Emery's team adds.
Never Too Late
Exercise strengthens bones and muscles, including the heart, and it's not just for the young.
"No one is too old to enjoy the benefits of regular physical activity," states the CDC's web site.
The CDC adds, "Evidence indicates that muscle-strengthening exercises can reduce the risk of falling and fracturing bones and can improve the ability to live independently" in older adults.
Check with a doctor before starting a new exercise program.