WEDNESDAY, Feb. 4 (HealthDay News) -- Exercise may play a key role in helping people recover from total knee replacement and knee osteoarthritis (OA), two new studies show.

After receiving a total knee replacement, patients following a six-week progressive strengthening program showed much improvement in strength, function and pain when compared to those following the conventional care of inpatient rehabilitation and home physical therapy, according to a University of Delaware study published in the February issue of Arthritis Care & Research.

Those in the exercise program -- which consisted of sessions focused on knee extension, range of motion, kneecap mobility, quadriceps strength, pain control and gait two to three times a week -- also showed much greater strength in their quadriceps and functional performance than the other group a year after the program.

Half of those in the exercise group also received neuromuscular electrical stimulation, but the additional treatment didn't seem to have any further effect on the results.

"Our data suggest that individuals who do not undertake an intensive rehabilitation program following [total knee replacement] are clearly at a disadvantage," the authors concluded. "Failing to obtain adequate functional recovery may accelerate functional decline and predispose these individuals to an early loss of functional independence as they age."

The other study, published in the same issue of Arthritis Care & Research, found that people who engaged in activities with low muscle strength (such as light household work) or high mechanical strain (such as dancing or tennis) had a greater risk of developing knee osteoarthritis.

VU University Medical Center in Amsterdam based its findings on physical activity questionnaires filled out by almost 1,700 seniors throughout a 12-year period. The activities were scored for intensity, mechanical strain, turning action and muscle strength, then evaluated. The findings also took into account demographics, health and physical activity from earlier in life.

The authors noted a particular lack of a link between being overweight and mechanical strain to knee osteoarthritis.

"This finding could indicate that the higher risk of knee OA in obese persons may be explained by factors other than increased mechanical strain, and higher levels of physical activity may not negatively affect knee health in heavier respondents," the authors wrote.