PT  - JOURNAL ARTICLE
AU  - Eduardo Foschini Miranda
AU  - Paulo Henrique Marchetti
AU  - Ernesto Cesar Pinto Leal Junior
AU  - Simone Dal Corso
TI  - Acute effects of light-emitting diodes on muscle fatigue during isometric exercise in patients with COPD: A pilot study
DP  - 2012 Sep 01
TA  - European Respiratory Journal
PG  - P620
VI  - 40
IP  - Suppl 56
4099  - http://erj.ersjournals.com/content/40/Suppl_56/P620.short
4100  - http://erj.ersjournals.com/content/40/Suppl_56/P620.full
SO  - Eur Respir J2012 Sep 01; 40
AB  - Background: Patients with chronic obstructive pulmonary disease (COPD) are susceptible to early muscle fatigue. Light-emitting diodes (LEDs) have been used to minimize muscle fatigue in athletes and healthy subjects. Aim: To investigate the acute effects of LEDs on muscle fatigue and perception of effort in patients with COPD during isometric endurance test of the quadriceps femoris (QF). Methods: Ten patients (VEF1 50 ± 13% of predicted) underwent a single LED and placebo (PL) application, 48 h apart, in a randomized, cross-over design. The LED and PL were applied in three localized areas of the QF (rectus femoris, vastus lateralis, and vastus medialis). Before and after exposure to LED and PL, patients performed an isometric endurance test (80% of the maximum voluntary isometric contraction) until the limit of tolerance concomitant to surface electromyography recording (median frequency as mean outcome). The slope obtained from linear regression analysis of the median frequency (MF) over endurance time was also used as an endurance index. Results: Endurance time increased significantly after exposure to LED (from 26 ± 2s to 53 ± 5s) as compared to PL (from 23 ± 3s to 30 ± 4s) (F = 64, P = 0.0001). A greater decline in MF was observed during isometric endurance test after placebo, compared to LED (F = 14.6, P = 0.004). The slope of the MF over time was lower post-LED compared to post-placebo (-0.7±0.3 vs. -1.5±0.8; P = 0.004). The dyspnea score corrected for endurance time was lower post-LED (P = 0.008), but similar for fatigue both post-LED and post-PL. Conclusion: A single application of LED minimizes muscle fatigue and increases isometric endurance time.