There are four possible explanations for this phenomenon. Firstly, most participants complained of muscle fatigue and knee pain after baseline concentric isokinetic testing. They might try performing lower force of knee extension at the following tests. Therefore, TLE might decrease because they fear developing knee pain. Secondly, before and after the isokinetic testing, all participants were instructed to perform muscle stretching. One study revealed that a 2.8 percent decrease in knee extension peak torque was found between pre stretching and post stretching exercise among healthy young adults; stretching also altered the muscle length-tension relationship and decreased muscle power during the isokinetic muscle strength testing. Thirdly, the provision of general information regarding osteoarthritis of the knee may have encouraged participants in the control group to increase activity and independently perform exercise. This result confinns previous findings that both the exercise and education groups improved isokinetic muscle strength after 8 weeks of the study. For this study, contamination between groups was lessened by a distance of over 10 kilometers between the experimental and the three control settings. The use of no intervention at all might have eliminated these limitation s. However, studying in a community setting could not account for the attention and socialization paid to both groups. Participants in the control group might perform some types of exercise provided for all community members . In addition, there were many women with knee pain related to osteoarthritis of the knee in the community to whom the researcher could not reach. Those women might not be elderly club members, or might still be full time workers, or be too busy. Therefore, generalization was limited to the special group of women in elderly club. The other possible factor contributing to the control group's improve ments might include the learning experiences during the isokinetic strength testing. All participants had to perform the same tests four times during the study period. Inter action with the machine and testing protocol may have been sufficient to produce some training effects. As van Barr and colleagues indicated that maturation may occur from several repeated measures.