Phototherapy during treadmill training improves quadriceps performance in postmenopausal women

Abstract

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/cm² and 108 J/cm² for 45 min. Quadriceps performance was measured during isokinetic exercise testing at 60°/s and 300°/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 (∆ = 21 ± 6 W and ∆ = 634 ± 156 J, p < 0.05) when compared to both the exercise group (∆ = 13 ± 10 W and = 410 ± 270 J) and the sedentary group (∆ = 10 ± 9 W and ∆ = 357 ± 327 J). Fatigue was also significantly lower in the LED group (∆ = −7 ± 4%, p < 0.05) compared to both the exercise group (∆ = 3 ± 8%) and the sedentary group (∆ = −2 ± 6%).

Conclusions Infrared-LED during treadmill training may improve quadriceps power and reduce peripheral fatigue in postmenopausal women.

Key words::

• PHOTOTHERAPY
• INFRARED
• PHYSICAL TRAINING
• MUSCLE PERFORMANCE
• POSTMENOPAUSE

ACKNOWLEDGEMENTS

We would like to thank the Fundação de Amparo à Pesquisa do Estado de São Paulo, Conselho Nacional de Desenvolvimento Científico e Tecnológico and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior for financial support. We also acknowledge the valuable technical assistance graciously provided by Ms. Juliana Cristina Milan (physical therapist), Ms. Isabela Verzola Aniceto (medical doctor) and Professor Nivaldo Antonio Parizotto, PhD (physical therapist).

Conflict of interest The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Source of funding The Fundação de Amparo à Pesquisa do Estado de São Paulo – Grant no. 98/14270-8, 2008/57858-9 and 2009/01842-0; Conselho Nacional de Desenvolvimento Científico e Tecnológico – Grant no. 573587/2008-6; and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.