New research, however, provides insight that may help patients with knee osteoarthritis get over the "pain hump" when they begin a program of physical activity: evidence that the increased pain immediately following exercise is short-lived.
"Explaining to patients that the increased pain they feel right after exercising isn't long-lasting -- and helping them cope with that temporary increase -- may help them stick with an exercise program long enough to obtain [a] long-term reduction in pain," says lead author Brian C. Focht, Ph.D., of East Carolina University.
Prior research, he notes, indicates that this reduction in pain can result not only in greater comfort, but also in a greater sense of psychological well being and more participation in physical activity.
To better understand the extent and duration of the pain caused by individual workouts or other types of activity, Focht and his colleagues recruited 32 adults with osteoarthritis in one or both knees who were involved in a larger study of arthritis, diet and activity called ADAPT. All were overweight or obese -- a factor known to exacerbate knee the negative impact osteoarthritis has on quality of life -- as well as older than 60 and reporting that their knee pain caused physical limitations and difficulty with daily activities.
Prior to their enrollment in ADAPT, all subjects had been sedentary.
Each participant carried a pager and a notebook for six consecutive days. Pager tones throughout each day signaled participants to record how much knee pain they felt, as well as factors that might influence that level, such as mood and any medications taken.
Every other day, participants engaged in a one-hour period of programmed exercise. On the other days, they refrained from this activity.
In general, the researchers report in the August issue of the Annals of Behavioral Medicine, participants rated their daily pain as weak to moderate. Pain on non-exercise days tended to follow a pattern: lowest when recording began at 7 a.m., rising gradually to its highest level at around 3 p.m., then falling gradually until recording stopped at 9:30 p.m.
On exercise days, the pain curve was similar but showed a significant spike immediately after exercise. This increase, Focht observes, was higher than expected based on the time of day, reported stress levels or use of medications, confirming that it was likely exercise-induced.
Of particular interest, Focht reports, is the researchers' observation that pain the participants reported immediately after exercising tended to abate in the evening, indicating that the exercise-induced pain increase typically did not linger.
"Given that exercise training has been found to be beneficial for the reduction of pain, our findings have significant implications for the role of exercise therapy in patients with knee osteoarthritis," Focht and his colleagues conclude.
Focht cautions that these findings may not apply to apply "to osteoarthritis patients experiencing distressing or excruciating pain," or to those who are "novice exercisers." Additional research, he notes, is needed to characterize the post-exercise pain response of such individuals.
The study was conducted at Wake Forest University, where funding came from the Claude D. Pepper Older Americans Independence Center and the General Clinical Research Center of Wake Forest University.
FOR MORE INFORMATION
Health Behavior News Service: (202) 387-2829 or www.hbns.org.
Interviews: Contact John Durham at (252) 328-6481 or firstname.lastname@example.org.
Annals of Behavioral Medicine: Contact Robert Kaplan, PhD, (619) 534-6058.