Phototherapy during treadmill training improves quadriceps performance in postmenopausal women

Objective To evaluate the effects of infrared-light-emitting diode (LED) during treadmill training on functional performance. Methods Thirty postmenopausal women aged 50-60 years were randomly assigned to one of three groups and successfully completed the full study. The three groups were: (1) the LED group, which performed treadmill training associated with phototherapy (n = 10); (2) the exercise group, which carried out treadmill training only (n = 10); and (3) the sedentary group, which neither performed physical training nor underwent phototherapy (n = 10). Training was performed over a period of 6 months, twice a week for 45 min per session at 85-90% of maximal heart rate, which was obtained during progressive exercise testing. The irradiation parameters were 100 mW, 39 mW/cm(2) and 108 J/cm(2) for 45 min. Quadriceps performance was measured during isokinetic exercise testing at 60 degrees/s and 300 degrees/s. Results Peak torque did not differ amongst the groups. However, the results showed significantly higher values of power and total work for the LED group (Delta= 21 +/- 6 W and Delta = 634 +/- 156 J, p < 0.05) when compared to both the exercise group (Delta = 13 +/- 10 W and Delta = 410 +/- 270 J) and the sedentary group (Delta = 10 +/- 9 W and Delta = 357 +/- 327 J). Fatigue was also significantly lower in the LED group (Delta = -7 +/- 4%, p < 0.05) compared to both the exercise group (Delta = 3 +/- 8%) and the sedentary group (Delta = -2 +/- 6%). Conclusions Infrared-LED during treadmill training may improve quadriceps power and reduce peripheral fatigue in postmenopausal women.