Time response of increases in ATP and muscle resistance to fatigue after low-level laser (light) therapy (LLLT) in mice

Abstract

Recently, low-level laser (light) therapy has been used to increase muscle performance in intense exercises. However, there is a lack of understanding of the time response of muscles to light therapy. The first purpose of this study was to determine the time response for light-emitting diode therapy (LEDT)-mediated increase in adenosine triphosphate (ATP) in the soleus and gastrocnemius muscles in mice. Second purpose was to test whether LEDT can increase the resistance of muscles to fatigue during intense exercise. Fifty male Balb/c mice were randomly allocated into two equal groups: LEDT-ATP and LEDT-fatigue. Both groups were subdivided into five equal subgroups: LEDT-sham, LEDT-5 min, LEDT-3 h, LEDT-6 h, and LEDT-24 h. Each subgroup was analyzed for muscle ATP content or fatigue at specified time after LEDT. The fatigue test was performed by mice repeatedly climbing an inclined ladder bearing a load of 150 % of body weight until exhaustion. LEDT used a cluster of LEDs with 20 red (630± 10 nm, 25 mW) and 20 infrared (850±20 nm, 50 mW) delivering 80 mW/cm 2 for 90 s (7.2 J/cm 2 ) applied to legs, gluteus, and lower back muscles. LEDT-6 h was the subgroup with the highest ATP content in soleus and gastrocnemius compared to all subgroups (P<0.001). In addition, mice in LEDT-6 h group performed more repetitions in the fatigue test (P<0.001) compared to all subgroups: LEDT-sham and LEDT-5 min (~600 %), LEDT-3 h (~200 %), and LEDT-24 h (~300 %). A high correlation between the fatigue test repetitions and the ATP content in soleus (r=0.84) and gastrocnemius (r=0.94) muscles was observed. LEDT increased ATP content in muscles and fatigue resistance in mice with a peak at 6 h. Although the time response in mice and humans is not the same, athletes might consider applying LEDT at 6 h before competition.

Can low-level laser therapy (LLLT) associated with an aerobic plus resistance training change the cardiometabolic risk in obese women? A placebo-controlled clinical trial

“…The authors demonstrating that phototherapy reduces lactate levels in the circulation due to increased local microcirculation and consequently increased in oxygen supply. As a consequence, there is an improvement in muscle fatigue, faster recovery of muscle damage and improved performance, both in humans and animals [34][35][36]38]. In this context, our research group demonstrated in exogenous obese rats that the association of low-level laser therapy (LLLT) plus moderate swimming training promoted decrease in adipocyte area and increase in the energetic demand and in the mitochondrial oxidative capacity besides greater workload (data not published).…”

Effects of low-level laser therapy (LLLT 808 nm) on lower limb spastic muscle activity in chronic stroke patients

“…LLLT can also accelerate cellular metabolic processes and increase synthesis of ATP [8] with an anti-inflammatory effect (release of inflammatory mediators, stimulation of microcirculation, absorption of exudates, and interference in the synthesis of prostaglandins) [12,13]. Research corroborates the influence of LLLT in relation to the recruitment of muscle fibers and the torque peak, in addition to delaying development of muscle fatigue, which contributes to a greater musculoskeletal performance [6,[14][15][16][17][18][19][20][21][22][23].…”

Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness

“…Moreover, increases in ATP content in muscle cells and tissue, fatigue resistance, strength, oxidative stress defense, prevention of muscle damage, and improvement of the kinetics of oxygen consumption 7,8,10,12,17,41–43 can also be elicited when phototherapy is applied to muscles before a single bout of exercise (muscular preconditioning). However, it seems there is an optimum time to apply phototherapy when used in a muscular preconditioning regimen as judged by increases in ATP synthesis in muscles, mitochondrial metabolism, and fatigue resistance that are maximal at some hours after light application.…”

“…However, it seems there is an optimum time to apply phototherapy when used in a muscular preconditioning regimen as judged by increases in ATP synthesis in muscles, mitochondrial metabolism, and fatigue resistance that are maximal at some hours after light application. 8,17 …”

“…11,13 Moreover, there has been no study reporting the chronic effects of phototherapy on muscle performance (including maximal load tests and fatigue resistance), hypertrophy, muscle damage, delayed-onset muscle soreness (DOMS), and molecular responses (gene expression) in humans. In addition, it is also important to establish the safety of this treatment applied in a chronic manner, because this therapy produces effects on muscle tissue lasting 24 to 48 hours, 8,16,17 suggesting possible cumulative effects if applied repetitively. Finally, no published study has controlled the genetic aspects of the subjects, because it is known that genetic differences between individual subjects can promote different adaptations to exercise.…”