Background: Muscle pain has important socioeconomic impact and regular exercise has been described as an efficient alternative therapy, not only for reducing pain, but also by the
absence of the common side effects of commercially available analgesics. However, it is well known that the body adapts to exercise intensity over time and individuals with chronic muscle pain
conditions usually respond to exercise differently from healthy individuals. These evidences suggest that an exercise protocol adjusted for individual physiological conditions may be interesting for a
significant reduction of muscle pain. Therefore, the aim of this study was to verify if a classical protocol of exercise, with generalized loads, and an individualized protocol of aerobic exercise
were able to enhance the muscle nociceptive threshold and compared the efficiency of both.
Methods:Male Wistar rats (200 – 250g) from the CEMIB-UNICAMP were used and all experimental procedures were approved by the Ethics Committee in Animal Research of UNICAMP (3869-1).
They were divided in control group (without exercise), classical exercise group (loads at 4% of body weight) and individualized exercise group (loads at 80% of the Maximum Lactate Steady State, MLSS).
The animals included in exercise groups were submitted to a water adaptation protocol and the MLSS test. The exercise protocol consisted of 40 min. of swimming, 5 days a week, during 10 weeks. After
five weeks of exercise, the loads of the individualized group were adjusted according to a new MLSS test. Every 2 weeks of exercise, the nociceptive threshold of rat´s gastrocnemius muscle was
performed by the analgesimeter Randall Selitto.
Results: Both exercise groups showed an increase in muscle nociceptive threshold after 10 weeks of exercise when compared to control group (p<0,05. Bonferroni test). In addition, the
individualized exercise group showed a better efficiency, from second week of exercise, in increasing muscle nociceptive threshold when compared to classical exercise and control groups (p<0,05.
Conclusions: These data demonstrated that chronic exercises are able to increase muscle nociceptive threshold. They also suggest that individualized protocols of exercises are more
efficient in reducing the perception of muscle pain.