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When is the best moment to apply photobiomodulation therapy (PBMT) when associated to a treadmill endurance-training program? A randomized, triple-blinded, placebo-controlled clinical trial

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Photobiomodulation therapy (PBMT) employing low-level laser therapy (LLLT) and/or light emitting diode therapy (LEDT) has emerged as an electrophysical intervention that could be associated with aerobic training to enhance beneficial effects of aerobic exercise. However, the best moment to perform irradiation with PBMT in aerobic training has not been elucidated. The aim of this study was to assess the effects of PBMT applied before and/or after each training session and to evaluate outcomes of the endurance-training program associated with PBMT. Seventy-seven healthy volunteers completed the treadmill-training protocol performed for 12 weeks, with 3 sessions per week. PBMT was performed before and/or after each training session (17 sites on each lower limb, using a cluster of 12 diodes: 4 × 905 nm super-pulsed laser diodes, 4 × 875 nm infrared LEDs, and 4 × 640 nm red LEDs, dose of 30 J per site). Volunteers were randomized in four groups according to the treatment they would receive before and after each training session: PBMT before + PBMT after, PBMT before + placebo after, placebo before + PBMT after, and placebo before + placebo after. Assessments were performed before the start of the protocol and after 4, 8, and 12 weeks of training. Primary outcome was time until exhaustion; secondary outcome measures were oxygen uptake and body fat. PBMT applied before and after aerobic exercise training sessions (PBMT before + PBMT after group) significantly increased (p < 0.05) the percentage of change of time until exhaustion and oxygen uptake compared to the group treated with placebo before and after aerobic exercise training sessions (placebo before + placebo after group) at 4th, 8th, and 12th week. PBMT applied before and after aerobic exercise training sessions (PBMT before + PBMT after group) also significantly improved (p < 0.05) the percentage of change of body fat compared to the group treated with placebo before and after aerobic exercise training sessions (placebo before + placebo after group) at 8th and 12th week. PBMT applied before and after sessions of aerobic training during 12 weeks can increase the time-to-exhaustion and oxygen uptake and also decrease the body fat in healthy volunteers when compared to placebo irradiation before and after exercise sessions. Our outcomes show that PBMT applied before and after endurance-training exercise sessions lead to improvement of endurance three times faster than exercise only.
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ORIGINAL ARTICLE
When is the best moment to apply photobiomodulation therapy (PBMT)
when associated to a treadmill endurance-training program? A
randomized, triple-blinded, placebo-controlled clinical trial
Eduardo Foschini Miranda
1
&Shaiane Silva Tomazoni
2
&Paulo Roberto Vicente de Paiva
1,3
&Henrique Dantas Pinto
1,3
&
Denis Smith
3
&Larissa Aline Santos
3
&Paulo de Tarso Camillo de Carvalho
3
&Ernesto Cesar Pinto Leal-Junior
1,3
Received: 18 June 2017 / Accepted: 20 November 2017
#Springer-Verlag London Ltd., part of Springer Nature 2017
Abstract
Photobiomodulation therapy (PBMT) employing low-level laser therapy (LLLT) and/or light emittingdiode therapy (LEDT) has
emerged as an electrophysical intervention that could be associated with aerobic training to enhance beneficial effects of aerobic
exercise. However, the best moment to perform irradiation with PBMT in aerobic training has not been elucidated. The aim of this
study was to assess the effects of PBMT applied before and/or after each training session and to evaluate outcomes of the
endurance-training program associated with PBMT. Seventy-seven healthy volunteers completed the treadmill-training protocol
performed for 12 weeks, with 3 sessions per week. PBMT was performed before and/or after each training session (17 sites on
each lower limb, using a cluster of 12 diodes: 4 × 905 nm super-pulsed laser diodes, 4 × 875 nm infrared LEDs, and 4 × 640 nm
red LEDs, doseof 30 J per site). Volunteers were randomized in four groups according to the treatment they would receive before
and after each training session: PBMT before + PBMT after, PBMT before + placebo after, placebo before + PBMT after, and
placebo before + placebo after. Assessments were performed before the start of the protocol and after 4, 8, and 12 weeks of
training. Primary outcome was time until exhaustion; secondary outcome measures were oxygen uptake and body fat. PBMT
applied before and after aerobic exercise training sessions (PBMT before + PBMT after group) significantly increased (p<0.05)
the percentage of change oftime until exhaustion and oxygenuptake compared tothe group treated with placebo before and after
aerobic exercise training sessions (placebo before + placebo after group) at 4th, 8th, and 12th week. PBMT applied before and
after aerobic exercise training sessions (PBMT before + PBMTafter group) also significantly improved(p< 0.05) the percentage
of change of body fat compared to the group treated with placebo before and after aerobic exercise training sessions (placebo
before + placebo after group) at 8th and 12th week. PBMT applied before and after sessions of aerobic training during 12 weeks
can increase the time-to-exhaustion and oxygen uptake and also decrease the body fat in healthy volunteers when compared to
placebo irradiation before and after exercise sessions. Our outcomes showthat PBMTapplied beforeand after endurance-training
exercise sessions lead to improvement of endurance three times faster than exercise only.
Keywords Low-level laser therapy .Light emitting diode therapy .Phototherapy .Fatigue .Exercise .Aerobic training
Introduction
Physical activity is recommended and beneficial for both
asymptomatic persons and individuals with chronic diseases
[1,2]. Aerobic endurance is considered a useful tool for the
assessment of physical fitness and the detection of changes in
aerobic fitness resulting from systematic training [3].
Regular aerobic exercise has various beneficial metabolic,
vascular, and cardiorespiratory effects [4]. Additionally, it de-
creases body fat and increases muscle mass, muscle strength,
and bone density [5]. Moreover, it improves self-esteem and
*Ernesto Cesar Pinto Leal-Junior
ernesto.leal.junior@gmail.com
1
Laboratory of Phototherapy in Sports and Exercise, Nove de Julho
University, Sao Paulo, SP, Brazil
2
Masters and Doctoral Programs in Physical Therapy, Universidade
Cidade de São Paulo (UNICID), Sao Paulo, SP, Brazil
3
Post-Graduate Program in Rehabilitation Sciences, Nove de Julho
University, Rua Vergueiro, 235/249, Sao Paulo, SP 01504-001,
Brazil
Lasers in Medical Science
https://doi.org/10.1007/s10103-017-2396-2
physical and mental health and reduces the incidence of anx-
iety and depression [4,6].
Various ergogenic agents, such as whey protein [7], caffeine
[8], creatine [9], and neuromuscular electrical stimulation [10],
are currently used to increase the benefits of aerobic training.
Photobiomodulation therapy (PBMT) has emerged as an
electrophysical intervention that could be associated with aero-
bic training to enhance beneficial effects of aerobic exercise,
since several studies used PBMT to improve physical perfor-
mance when associated with different kinds of exercise [1114].
Several studies have recently used PBMT to improve muscle
performance during aerobic activities in healthy adults [1518]
and postmenopausal women [19,20]. However, to the best of
our knowledge, the best moment to perform irradiation with
PBMT in aerobic training has not been yet elucidated.
For instance, the current literature shows that the applica-
tion of PBMT before progressive aerobic exercise has ergo-
genic effects and acutely increases the time until exhaustion,
covered distance, and pulmonary ventilation and decreases the
score of dyspnea during progressive cardiopulmonary test
[15]. In addition, PBMTirradiation performed prior toaerobic
exercises improves the exercise performance by decreasing
the exercise-induced oxidative stress and muscle damage
[18] and increasing the oxygen extraction by peripheral mus-
cles [16]. When performed during aerobic training sessions,
PBMT improves the quadriceps power and reduces the pe-
ripheral fatigue in postmenopausal women [19,20].
Additionally, when applied after the sessions of endurance-
training program, PBMT leads to a greater fatigue reduction
than endurance training without PBMT irradiation [17].
Therefore, the optimal moment to perform PBMT in aero-
bic training is still open to discussion. With this perspective in
mind, we aimed to assess the effects of PBMT applied at
different time points (before and/or after) of each training ses-
sion and its potential effects on the outcomes of an endurance-
training program (aerobic exercise).
Materials and methods
Study design and protocol
We performed a triple-blind (assessors, therapists, and volun-
teers), placebo-controlled, randomized clinical trial. The study
was conducted in the Laboratory of Phototherapy in Sports
and Exercise.
Ethical aspects
All participants signed informed consent prior to enrollment
and the study was approved by the research ethics committee
of Nove de Julho University (process 553.831) and registered
at Clinical Trials.gov (NCT02874976).
Sample
The sample size was calculated assuminga type I error of 0.05
and a type II error of 0.2, based on previous study [21], and the
primary established outcome was the time until exhaustion.
Inclusion and exclusion criteria
We recruited 96 healthy volunteers (48 men and 48 women)
between 18 and 35 years of age and without training or in-
volvement in a regular exercise program (i.e., exercise more
than once per week) [22,23]. Volunteers were excluded if they
had any skeletal muscle injury, used any nutritional supple-
ment or pharmacologic agent, presented with signs or symp-
toms of any disease (i.e., neurologic, inflammatory, pulmo-
nary, metabolic, oncologic), or had a history of cardiac arrest
that might limit performance of high-intensity exercises.
Volunteers that were unable to attend a minimum rate of
80% of the training sessions and volunteers with immune
diseases that require continuous use of anti-inflammatory
drugs were also excluded.
Randomization and blinding procedures
Volunteers were distributed in four experimental groups (24
volunteers in each group) through a simple drawing of lots (A,
B, C, or D) that determined the moment they would receive
active and/or placebo PBMT treatment:
PBMT + PBMT: volunteers were treated with active
PBMT before and after each training session.
PBMT + placebo: volunteers were treated with active
PBMT before and placebo PBMT after each training
session.
Placebo + PBMT: volunteers were treated with placebo
PBMT before and active PBMT after each training
session.
Placebo + placebo: volunteers were treated with placebo
PBMT before and after each training session.
Randomization labels were created by using a randomiza-
tion table at a central office where a series of sealed, opaque,
and numbered envelopes ensured confidentiality. The re-
searcher who programmed the PBMT device (manufactured
by Multi Radiance Medical, Solon, OH, USA) based on the
randomization results was not involved in any other procedure
of the study. He was instructed not to inform the participants
or other researchers of the PBMT program (active or placebo).
None of the researchers involved in aerobic endurance-
training assessments and data collection knew which program
corresponded to active or placebo PBMT.
Identical PBMT devices were used in both programs (ac-
tive or placebo) by a researcher who was not involved in any
Lasers Med Sci
phase of the projected data collection to ensure the study
blinding. All displays and sounds emitted were identical re-
gardless of the selected program. The active PBMT treatment
did not demonstrate discernable amounts of heat [24].
Therefore, volunteers were unable to differentiate between
active or placebo treatments. All volunteers were required to
wear opaque goggles during treatments to safety and to main-
tain the triple-blind design.
Procedures
The study included three sessions of aerobic endurance train-
ing per week performed over 12 weeks, and each session
lasted 30 min; the load for each exercise session (treadmill
speed) progressed constantly in order to keep subjectsheart
rate between 70 and 80% from maximum heart rate. The as-
sessments were conducted before the start of the training pro-
tocol and after 4, 8, and 12 weeks of training. A summary of
the study design is presented in Fig. 1.
Cardiopulmonary exercise test
Participants performed a standardized progressive cardiopul-
monary exercise test on a treadmill with a fixed inclination of
1% until exhaustion. They began the test with a 3-min warm-
up at a velocity of 3 km/h. Next, the treadmill velocity was
increased by 1 km/h at 1-min intervals until the velocity of
16 km/h was reached. Participants were instructed to use hand
signals to request termination of the test at any time. A 3-min
recovery phase at a velocity of 6 km/h was allowed after each
test [18]. During testing, we monitored the rates of oxygen
uptake (VO
2
), carbon dioxide production measured with a
VO 2000 gas analyzer (Inbrasport, Indústria Brasileira de
Equipamentos Médico-Desportivos LTDA, Porto Alegre,
RS, Brazil), total time until exhaustion, and heart rate mea-
suredwithadigitalelectrocardiograph (Medical Graphs
Ergomet, São Paulo, SP, Brazil).
These data were used to evaluate the performance of par-
ticipants during progressive cardiopulmonary exercise testing,
because this test is currently the most widely used in the liter-
ature for this purpose [25]. The entire test was monitored by
electrocardiogram and blood pressure measurement. If any
abnormal heart rate or blood pressure changes were observed
or if the test was terminated prematurely on request, the test
was stopped, and the volunteers data were deleted.
Body composition assessment
Body composition was assessed by the same technician
(blinded to volunteers allocation in different experimental
groups) using the procedures established by ISAK [26].
Measurements of height, body mass, and skinfolds were used
to establish the percentage of fat [26].
Aerobic training protocol
Aerobic treadmill training, associated or not with PBMT, was
performed three times a week for 12 weeks, each session
lasting 30 min, with training intensity kept between 70 and
80% of maximum heart rate [27]; changes in running speed
(training load) were constantly performed to achieve the 70
80% heart rate.
Training was interrupted based on the criteria established
by the guidelines of the American Heart Association. Training
intensity was monitored by a heart rate monitor manufactured
by Polar®.
Fig. 1 CONSORT flowchart
Lasers Med Sci
Photobiomodulation therapy
PBMT was applied employing MR4 Laser Therapy Systems
outfitted with LaserShower 50 4D emitters (both
manufactured by Multi Radiance Medical, Solon, OH,
USA). The cluster style emitter contains 12 diodes composing
of four super-pulsed laser diodes (905 nm, 0.3125 mW aver-
age power, and 12.5 W peak power for each diode), four red
LED diodes (640 nm, 15 mW average power for each diode),
and four infrared LEDs diodes (875 nm, 17.5 mW average
power for each diode).
The cluster probe was selected due to the available cover-
age area and to reduce the number of sites needing treatment.
Treatment was applied in direct contact with the skin with a
slight applied overpressure to nine sites on extensor muscles
of the knee (Fig. 2a), six sites on kneeflexors of the knee, and
two sites on the calf (Fig. 2b) of both lower limbs [15,28]. To
ensure blinding, the device emitted the same sounds and re-
gardless of the programmed mode (active or placebo). The
researcher, who was blinded to randomization and the pro-
gramming of PBMT device, performed the PBMT.
PBMT parameters and irradiation sites were selected based
upon previous positive outcomes demonstrated with the same
family of device [13,15,28,29]. Table 1provides a full
description of the PBMT parameters. The volunteers received
PBMTor placebo from 5 to 10 min before and/or after aerobic
training sessions.
Statistical analysis
The obtained results were tested for their normality through
the Shapiro-Wilk test. Since the data showed a normal
distribution, two-way ANOVA test with Bonferroni post hoc
analysis was applied. The data were described as mean values
with the respective standard deviations and both absolute and
percentage values were analyzed. Graphical data are described
as mean and standard errors of mean (SEM). The level of
statistical significance was p<0.05.
Results
After data collection, we analyzed the results of 77 volunteers
of both genders (PBMT + PBMT: 18 volunteers; PBMT +
placebo: 21 volunteers; placebo + PBMT: 18 volunteers; and
placebo + placebo: 20 volunteers) that had completed the aer-
obic training protocol after 12 weeks (Fig. 1). None of the
recruited volunteers were excluded due abnormal heart rate or
Fig. 2 aTreatment sites at knee extensor muscles. bTreatment sites at
knee flexor and ankle plantar flexor muscles
Table 1 PBMT parameters
Number of lasers 4 Super-pulsed infrared
Wavelength (nm) 905 (± 1)
Frequency (Hz) 250
Peak power (W)each 12.5
Average mean optical output (mW)each 0.3125
Power density (mW/cm
2
)each 0.71
Energy density (J/cm
2
)each 0.162
Dose (J)each 0.07125
Spot size of laser (cm
2
)each 0.44
Number of red LEDs 4 red
Wavelength of red LEDs (nm) 640 (± 10)
Frequency (Hz) 2
Average optical output (mW)each 15
Power density (mW/cm
2
)each 16.66
Energy density (J/cm
2
)each 3.8
Dose (J)each 3.42
Spot size of red LED (cm
2
)each 0.9
Number of infrared LEDs 4 Infrared
Wavelength of infrared LEDs (nm) 875 (± 10)
Frequency (Hz) 16
Average optical output (mW)each 17.5
Power density (mW/cm
2
)each 19.44
Energy density (J/cm
2
)each 4.43
Dose (J)each 3.99
Spot size of LED (cm
2
)each 0.9
Magnetic field (mT) 35
Irradiation time per site (s) 228
Total dose per site (J) 30
Total dose applied per lower limb (J) 510
Aperture of device (cm
2
)20
Application mode Cluster probe held stationary
in skin contact with a 90°
angle and slight pressure
Lasers Med Sci
blood pressure during the execution of procedures of this study.
The characteristics of the volunteers are summarized in Table 2.
As shown in Table 2, no statistically significant differences
(p> 0.05) were found for anthropometric variables and base-
line data among the different experimental study groups.
Table 3shows all results of cardiopulmonary progressive
test in absolute values for different variables analyzed in all
experimental groups of this study. We observed a statistically
significant improvement in oxygen uptake when PBMT was
performed before and after training sessions (PBMT + PBMT
group), comparing baseline values vs 4-, 8-, and 12-week
values (p< 0.001). The same was observed for pulmonary
ventilation, comparing baseline values vs 8- and 12-week
values (p=0.0018and p= 0.003, respectively), and for time
until exhaustion, comparing baseline values vs 4-, 8-, and 12-
week values (p<0.001).
Furthermore, PBMT applied before and after each aerobic
exercise training session (PBMT + PBMT group) significant-
ly increased (p< 0.05) the percentage change of oxygen con-
sumption and time-to-exhaustion compared to the group treat-
ed with placebo before and after each aerobic exercise training
session (placebo + placebo group) from 4th to 12th week.
Similarly, PBMT applied before and after each aerobic exer-
cise training session (PBMT + PBMT group) significantly
improved (p< 0.05) the percentage change of body fat com-
pared to group treated with placebo before and after each
aerobic exercise training session (placebo + placebo group).
The outcomes are summarized in Figs. 3,4,and5,
respectively.
Discussion
To the best of our knowledge, this is the first study aiming to
test the optimal moment to perform PBMT in an aerobic train-
ing protocol (before, after, or before and after training). Few
studies have assessed chronic effects of PBMT [17,20,21];
however, PBMT has been applied at different moments (be-
fore, after, or during exercise) of the aerobic training program.
Briefly, we observed that the combination of super-pulsed
lasers and LEDs applied before and after exercise sessions
increased the oxygen uptake, time-to-exhaustion, and reduced
body fat in healthy sedentary volunteers after 12 weeks of
aerobic training.
Paolillo et al. [20] investigated the effects of PBMT applied
during the sessions of aerobic training on the treadmill in 20
postmenopausal women. The training was performed twice a
week for 3 months, with an intensity of 8590% of maximum
heart rate. The volunteers received LEDtherapy with 850 nm,
31 mW/cm
2
, 30 min irradiation, and 14,400 J applied bilater-
ally to the tight regions. PBMT increased the exercise toler-
ance time when compared to the control group. These data
corroborate with the results of our study, however, we used
different light sources and wavelengths simultaneously (4×
905 nm super-pulsed lasers, 4 × 875 nm infrared LEDs, and
4 × 640 nm red LEDs) to irradiate the volunteersand we found
an increase in exercise tolerance of 13.4%. The magnitude of
the difference in outcomes between studies might be related to
the used irradiation protocol (in our study, the volunteers were
irradiated before and after the aerobic training sessions, while
Paolillo et al. [20] irradiated volunteers during the training
sessions).
The same authors [21] also investigated the effects of
PBMT (infrared LEDs850 nm) when applied during tread-
mill training in 45 postmenopausal women. The training was
performed twice a week for 6 months, and each training ses-
sion lasted 45 min. The authors found a significant increase in
exercise tolerance, and metabolic equivalents, and a longer
duration of Bruce test. In our study, the association of
PBMT before and after sessions of the aerobic training pro-
gram was able to increase the oxygen consumption (with
18.7%) and time-to-exhaustion (with 13.4%) and improve
the percentage of change of body fat (with 13.9%) after only
12 weeks of aerobic training.
Table 2 Baseline assessment data in absolute values
PBMT + PBMT PBMT + placebo Placebo + PBMT Placebo + placebo
Age (years) 24.7 ± 4.7 26.1 ± 5.2 26 ± 5.3 25.1 ± 4.6
Body mass index
a
26.0 ± 3.6 25.3 ± 2.8 24.9 ± 2.7 25.2 ± 1.9
Heart rate (beats per minute) 94.2± 15.0 87.8 ± 13.5 89.9 ± 11.9 95.1 ± 14.7
Systolic blood pressure (mmHg) 117.1 ± 12.1 118.4 ± 13.8 118.0 ± 10.1 111.2 ± 13.5
Diastolic blood pressure (mmHg) 84.7 ± 10.1 84.2 ± 8.4 84.7 ± 6.4 81.2 ± 10.1
Time until exhaustion (s) 681.5 ± 111.9 698.7 ± 131.3 693.1 ± 106.9 699.5 ± 137.3
VO
2
max (mL/kg/min) 35.8 ± 9.5 34.8 ± 6.9 35.2 ± 8.9 36.2 ± 7.7
Fat percentage 31.8 ± 10.4 29.5 ± 14.4 28.9 ± 11.1 30.1 ± 13.7
Data is expressed in average and standard deviation (±)
VO
2
max oxygen uptake
a
Calculated as kilograms per square meter
Lasers Med Sci
Duarte et al. [30] evaluated the effects of PBMT (808 nm)
associated with aerobic and resistance training performed
three times a week for 16 weeks in obese women. The authors
found a significant decrease in the percentage of fat and in
neck and waist circumference. It is important to highlight that
in our study, we observed statistically significant improve-
ment in the percentage of change of body fat (13.9%) after
only 12 weeks of aerobic training when associated with
PBMT before and after the training sessions. We believe that
the association of PBMT before and after training was able to
enhance the performance and the tolerance of the volunteers
during the aerobic training protocol, favoring the reduction of
the body fat at the end of the 12 weeks of training.
It is interesting how outcomes in the fourth week for PBMT
+ PBMT group were similar to those of placebo + placebo
group (or exercise alone) in the 12th week. This means that
PBMT with optimal irradiation protocol (before and after ex-
ercise training sessions) can increase the endurance capacity
of volunteers three times faster than exercise alone.
Regarding the mechanisms of the observed effects, we
strongly believe that mitochondrial activity modulation is the
key mechanism, despite the fact that our study only focused
on clinical and functional aspects and not on mechanisms.
Hayworth et al. [31] demonstrated that the activity of cyto-
chrome c oxidase is enhanced by PBMT with a single wave-
length in skeletal muscle fibers of rats. More recently,
Albuquerque-Pontes et al. [32] showed that PBMT with dif-
ferent wavelengths (660, 830, or 905 nm) was able to increase
the expression of cytochrome c oxidase in the intact skeletal
Table 3 Progressive endurance test variables
Baseline 4 weeks 8 weeks 12 weeks
VO
2
(mL/kg/min) PBMT + PBMT 35.8 ± 9.5 40.2 ± 10.2* 41.5 ± 10.4* 42.5 ± 11.2*
PBMT + Placebo 34.8 ± 7.0 37.6 ± 7.0 38.6 ± 8.0 38.2 ± 7.0
Placebo + PBMT 35.2 ± 8.9 36.6 ± 8.1 38.6 ± 8.3 38.5 ± 8.3
Placebo + placebo 36.2 ± 7.7 36.8 ± 8.0 37.6 ± 7.5 38.4 ± 10.1
VCO
2
(mL/kg/min) PBMT + PBMT 38.7 ± 7.0 40.4 ± 8.6 41.3 ± 7.8 41.4 ± 8.7
PBMT + placebo 38.,5 ± 7.8 39.5 ± 6.6 41.7 ± 7.9 41.9 ± 6.8
Placebo + PBMT 38.5 ± 9.5 38.2 ± 9.5 41.5 ± 8.4 40.7 ± 9.6
Placebo + placebo 38.8 ± 10.6 40.7 ± 9.4 43.1 ± 13.4 40.9 ± 10.5
VE (mL/kg/min) PBMT + PBMT 73.6 ± 22.8 77.9 ± 21.5 83.5 ± 24.5* 85.3 ± 22.5*
PBMT + Placebo 70.6 ± 20.3 71.0 ± 23.1 78.1 ± 23.0 77.2 ± 22.1
Placebo + PBMT 66.2 ± 25.3 70.6 ± 24.2 73.9 ± 20.6 73.4 ± 20.7
Placebo + placebo 69.9 ± 17.9 70.8 ± 18.8 70.3 ± 22.4 77.1 ± 18.3
Time until exhaustion (s) PBMT + PBMT 681.5 ± 111.9 752.1 ± 111.7* 787.7 ± 114.2* 808.5 ± 124.5*
PBMT + placebo 698.7 ± 131.1 739.3 ± 142.2 773.4 ± 165.9 792.1 ± 186.9
Placebo + PBMT 693.1 ± 106.9 738.4 ± 116.6 766.1 ± 121.0 797.0 ± 139.0
Placebo + placebo 699.5 ± 137.3 720.2 ± 150.0 741.3 ± 154.3* 766.1 ± 159.8*
Data is expressed in average and standard deviation (±)
VO
2
oxygen uptake, VCO
2
carbon dioxide production, VE pulmonary ventilation
*Statistically significant difference compared to baseline (p<0.05)
Fig. 4 Percentage of change in maximum oxygen uptake. The data are
presented in mean and SEM. Letter a indicates statistical significance
between PBMT + PBMT and placebo + placebo (p<0.05)
Fig. 3 Percentage of change in time-to-exhaustion. The data are
presented in mean and SEM. Letter a indicates statistical significance
between PBMT + PBMT and placebo + placebo (p<0.05)
Lasers Med Sci
muscle tissue in different time windows (5 min to 24 h after
irradiation), which means that the muscle metabolism can be
improved through the action of PBMT. These findings help us
to explain the increase in performance observed by the use of
PBMT associated with an aerobic training protocol and pro-
vide the rationale for the concurrent use of different wave-
lengths at the same time, which can represent a therapeutic
advantage in various clinical situations.
In fact, different studies have shown that the concurrent use
of different light sources and wavelengths enhances muscular
performance [1315,28,29,33] decreases pain [34], in-
creases cytochrome c oxidase activity [32], decreases fatigue
development [35], and protects muscles against gradually
worsening damage [35].
In a previous study from our research group with a similar
purpose [36], it was observed that the best moment to perform
PBMT associated to strength training is before each exercise
session. As mentioned before, the current study showed that the
optimal moment to perform PBMT is before and after each
treadmill endurance-training exercise session. It clearly demon-
strates that not only doses [13,37] and power output [42], but
also the moment to apply PBMT should be optimized, since
different types of exercises [38] may need different optimal
moments to perform PBMT for achieving the best outcome.
We believe that our study results are interesting because
they show thatPBMT can chronically enhance aerobic perfor-
mance (endurance) and demonstrate that optimal moment to
perform PBMT associated with aerobic treadmill exercise is
before and after each exercise session. These outcomes can be
helpful to improve the scientific evidence [3941] in this
promising and growing area.
Conclusion
PBMT (with simultaneous combination of super-pulsed la-
sers, infrared, and red LEDs) applied before and after sessions
of aerobic training during 12 weeks can increase oxygen up-
take and time-to-exhaustion and decrease body fat in healthy
volunteers when compared to placebo irradiation before and
after exercise sessions.
Funding information This study was supported by research grants 2010/
52404-0 from São Paulo Research FoundationFAPESP (Professor
Ernesto Cesar Pinto Leal-Junior), 472062/2013-1 and 307717/2014-3
from Brazilian Council of Science and Technology Development
CNPq (Professor Ernesto Cesar Pinto Leal-Junior), and 2014/01279-1
from São Paulo Research FoundationFAPESP for Ph.D. scholarship
(Larissa Aline Santos).
Compliance with ethical standards
Competing interests Professor Ernesto Cesar Pinto Leal-Junior re-
ceived research support from Multi Radiance Medical (Solon, OH,
USA), a laser device manufacturer. The remaining authors declare that
they have no conflict of interest.
Ethical aspects All experimental procedures were submitted and ap-
proved by the Research Ethics Committee of Nove de Julho University
(process number 553.831) and registered at Clinical Trials.gov
(NCT02874976).
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... Since then, the body of evidence about the use of PBMT as a post-exercise recovery strategy has become robust, including two systematic reviews with meta-analysis [11,12]. In addition, PBMT has been used combined with static magnetic field (sMF) in order to have better effects from the synergy between these two therapeutic agents [15][16][17][18][19][20][21], generating a greater transfer of electrons [22]. sMF interacts with biological systems triggering physiological effects [23]. ...
... sMF enhances the positive effects of PBMT increasing mitochondrial respiratory chain activity, production of adenosine triphosphate (ATP), and consequently increasing cell metabolism [22]. Therefore, PBMT-sMF as well as PBMT alone, has been shown to be an effective ergogenic agent [15][16][17][18][19][20][21]. Furthermore, in clinical settings PBMT-sMF has shown better ergogenic effects that PBMT alone [24]. ...
... The PBMT-sMF irradiation protocol applied in our trial can be used before training to improve strength in post-injury rehabilitation, as previously demonstrated [15] and possibly may be used in detraining after a strength-training protocol [34]. Furthermore, our results demonstrated that, as previously described [15][16][17][18][19][20][21], PBMT-sMF as well as PBMT alone, can be considered an interesting intervention to decrease skeletal muscle fatigue and acts as an ergogenic agent. We observed through the fatigue index that PBMT-sMF was able to improve the volunteers' performance in the final third in relation to the first third of the second set of the exercise protocol performed [31]. ...
Article
There is evidence about the effects of photobiomodulation therapy (PBMT) alone and combined with a static magnetic field (PBMT-sMF) on skeletal muscle fatigue, physical performance and post-exercise recovery in different types of exercise protocols and sports activity. However, the effects of PBMT-sMF to improve the subsequent performance after a first set of exercises are unknown. Therefore, the aim of this study was to investigate the effects of PBMT-sMF, applied between two sets of exercises, on the subsequent physical performance. A randomized, crossover, triple-blinded (assessors, therapist, and volunteers), placebo-controlled trial was carried out. Healthy non-athlete male volunteers were randomized and treated with a single application of PBMT-sMF and placebo between two sets of an exercise protocol performed on isokinetic dynamometer. The order of interventions was randomized. The primary outcome was fatigue index and the secondary outcomes were total work, peak work, and blood lactate levels. Twelve volunteers were randomized and analyzed to each sequence. PBMT-sMF decreased the fatigue index compared to the placebo PBMT-sMF at second set of the exercise protocol (MD = -6.08, 95% CI -10.49 to -1.68). In addition, PBMT-sMF decreased the blood lactate levels post-intervention, and after the second set of the exercise protocol compared to placebo (p<0.05). There was no difference between PBMT-sMF and placebo in the remaining outcomes tested. Volunteers did not report adverse events. Our results suggest that PBMT-sMF is able to decrease skeletal muscle fatigue, accelerating post-exercise recovery and, consequently, increasing subsequent physical performance when applied between two sets of exercises.
... Phototherapy may employ light emitting diodes, lasers, and broadband light ranging on the spectrum from visible to infrared. 7 Phototherapy has been shown to potentiate aerobic performance, [8][9][10][11][12][13][14] increase the number of muscular contractions that can be performed prior to fatigue, [15][16][17][18][19][20][21][22][23] and hasten recovery following exercise-induced muscle damage. 10,16,21,[24][25][26][27][28][29][30][31] While tenets of the treatment vary (dosage, pre vs. post exercise application, pulsed vs. continuous application), PhT generally appears to enhance some types of performance. ...
Article
Full-text available
Background Intense physical activity can result in exercise-induced muscle damage, delayed-onset muscle soreness, and decrements in performance. Phototherapy (PhT), sometimes referred to as photobiomodulation or low-level laser therapy, may enhance recovery from vigorous exercise. Purpose The purpose of this study was to assess the influence of phototherapy on functional movements (vertical jump, agility), and perceptions of muscle soreness following exercise-induced muscle damage caused by high volume sprinting and decelerations. Methods In a between-group design, 33 participants performed 40x15m sprints, a protocol intended to cause muscle damage. Immediately following sprinting and in the four days following, vertical jump and agility were assessed, as well as calf, hamstring, quadriceps, and overall perceptions of soreness. Sixteen subjects (age 20.6±1.6 yrs; BMI 25.8±4.6 kg.m-2) received PhT prior to testing each day, while 17 (age 20.8±1.3 yrs; BMI 26.2±4.5 kg.m-2) received sham PhT and served as a control (CON). Measurements were recorded during five days of recovery from the repeated sprint protocol, then compared to those recorded during three baseline days of familiarization. Area under the curve was calculated by summing all five scores, and comparing those values by condition via a two-tailed unpaired t-test for normally distributed data, and a two-tailed Mann-Whitney U test for nonparametric data (alpha level = 0.05). Results Calf soreness was lower in PhT compared to CON ( p = 0.02), but no other significant differences were observed between groups for vertical jump, agility, quadriceps, hamstring, and overall soreness ( p > 0.05). Discussion Phototherapy may attenuate soreness in some muscle groups following exercise-induced muscle damage, but may not enhance recovery after explosive, short-duration activities. Conclusion Phototherapy may not be a useful recovery tool for those participating in explosive, short-duration activities. Level of evidence 2c
... However, the combination of PBMT and SMF (PBMT-SMF) demonstrated remarkable synergy, leading to enhanced electron transfer and consequent activation of the mitochondrial respiratory chain and ATP production [16]. In addition, studies have shown that PBMT-SMF improves muscle performance in healthy individuals [17,18] and athletes [19,20], decreases pain intensity in people undergoing total hip arthroplasty [21], decreases dyspnea intensity in people with chronic obstructive pulmonary disease [22], and improves functional mobility in post-stroke people [23]. ...
Article
Full-text available
Background: Gait deficit is a major complaint in patients after stroke, restricting certain activities of daily living. Photobiomodulation therapy combined with a static magnetic field (PBMT-SMF) has been studied for several diseases, and the two therapies are beneficia. However, their combination has not yet been evaluated in stroke. Therefore, for PBMT-SMF to be used more often and become an adjunctive tool in the rehabilitation of stroke survivors at physical therapy rehabilitation centers and clinics, some important aspects need to be clarified. Purpose: This study aimed to test different doses of PBMT-SMF, to identify the ideal dose to cause immediate effects on the spatiotemporal and kinematic variables of gait in post-stroke patients. Methods: A randomized, triple-blinded, placebo-controlled crossover pilot study was performed. A total of 10 individuals with hemiparesis within 6 months to 5 years since the occurrence of stroke, aged 45-60 years, were included in the study. Participants were randomly assigned and treated with a single PBMT-SMF dose (sham, 10 J, 30 J, or 50 J) on a single application, with one dose per stage at 7-day intervals between stages. PBMT-SMF was applied with a cluster of 12 diodes (4 of 905 nm laser, 4 of 875 nm LEDs, and 4 of 640 nm LEDs, SMF of 35 mT) at 17 sites on both lower limbs after baseline evaluation: plantar flexors (2), knee extensors (9), and flexors (6). The primary outcome was self-selected walking speed, and the secondary outcomes were kinematic parameters. Gait analysis was performed using SMART-D 140® and SMART-D INTEGRATED WORKSTATION®. The outcomes were measured at the end of each stage after the single application of each PBMT-SMF dose tested. Results: No significant differences (p > 0.05) in spatiotemporal variables were observed between the different doses, compared with the baseline evaluation. However, differences (p < 0.05) were observed in the kinematic variable of the hip in the paretic and non-paretic limbs, specifically in the minimum flexion/extension angulation during the support phase (HMST-MIN) in doses 10 J, 30 J, and 50 J. Conclusions: A single application of PBMT-SMF at doses of 10 J, 30 J, and 50 J per site of the lower limbs did not demonstrate positive effects on the spatiotemporal variables, but it promoted immediate effects in the kinematic variables of the hip (maximum and minimum flexion/extension angulation during the support phase) in the paretic and non-paretic limbs in post-stroke people.
... As already mentioned, this treatment is scientifically based on the assumption that PBM stimulates mitochondrial chains and the cytochrome C oxidase enzyme, which increases ATP production and thus delays muscle fatigue and protects muscle from injury [60,61]. PBM stops the release of muscle damage markers (LDH and CK), proinflammatory protein production (CRP), improves the oxidative system, and increases muscle plugging power [62,63]. Studies on the effects of PBM on muscle performance and fatigue, with various protocols related to wavelength, power density, irradiation time, and laser light sources still reported discordant results [64,65]. ...
Article
Full-text available
Benefits of photobiomodulation (PBM) have been known for several decades. More recently, PBM applied in sports offers a special chance to support the modeling of the performance and recovery. Increasingly complex physical activities and fierce competition in the world of sports generate a state of psycho-emotional and physical stress that can induce chronic fatigue syndrome, failure in physical training, predisposition to muscle damage, physical and emotional exhaustion etc., for which PBM could be an excellent solution. To evaluate and identify all risk factors and the influence of PBM on health and performance in sport and for a better understanding of its effects, we did a search for “Photobiomodulation and Sports” on PubMed, to update the PBM science applied in sports, and we retained for analysis the articles published from 2014 to date. The term “PBM” is recent, and we did not include previous studies with “low level laser therapy” or “LLLT” before 2014. In the present research, PBM has been shown to have valuable protective and ergogenic effects in 25 human studies, being the key to success for high performance and recovery, facts supported also by 22 animal studies. PBM applied creatively and targeted depending on sport and size of the level of physical effort could perfectly modulate the mitochondrial activity and thus lead to remarkable improvements in performance. PBM with no conclusive results or without effects from this review (14 studies from a total of 39 on humans) was analyzed and we found the motivations of the authors from the perspective of multiple causes related to technological limitations, participants, the protocols for physical activity, the devices, techniques and PBM parameters. In the near future, dose–response experiments on physical activity should be designed and correlated with PBM dose–response studies, so that quantification of PBM parameters to allow the energy, metabolic, immune, and neuro-endocrine modulation, perfectly coupled with the level of training. There is an urgent need to continuously improve PBM devices, delivery methods, and protocols in new ingenious future sports trials. Latest innovations and nanotechnologies applied to perform intracellular signaling analysis, while examining extracellular targets, coupled with 3D and 4D sports motion analysis and other high-tech devices, can be a challenge to learn how to maximize PBM efficiency while achieving unprecedented sports performance and thus fulfilling the dream of millions of elite athletes.
... The suggested mechanism of LLLT action is the stimulation of the mitochondrial system and the effect on cytochrome C oxidase that enhances muscle power due to the acceleration of ATP production, leading to fatigue delay and protection of muscle against injury (18,19). LLLT decreases the production of fatigue-associated markers such as LDH, CRP, and CK (19) and, by enhancing the oxidase system, reduces oxidative stress and elevates muscle buffering capacity (20)(21)(22). ...
Article
Background Previous studies have shown positive results of photobiomodulation (PBM) for improving performance and accelerating post-exercise recovery. However, the effects of PBM in healthy individuals who underwent a neuromuscular adaptation training remain unclear. Objective To investigate the effects of PBM during a training program combining sprints and explosive squats exercises on clinical, functional, and systemic outcomes in trained healthy individuals compared to a placebo intervention and a control. Methods We conducted a randomized placebo-controlled trial. Healthy males were randomly assigned to three groups: active PBM (30 J per site), placebo, or control (passive recovery). The participants performed a six-week (12 sessions) of a training program consisting of a combination of sprints and squats with recovery applied between sprints and squats. To prevent the influence of the primary neuromuscular adaptation to exercise on the results, all participants had to participate in a period of six weeks of exercise training program. Functional, clinical, and psychological outcomes and vascular endothelial growth factor (VEGF) were assessed at baseline and after six weeks. Results are expressed as mean difference (MD) and 95% confidence intervals (CI). Results Thirty-nine healthy male volunteers (aged 18–30 years; body mass index 23.9 ± 3 kg/m²) were recruited. There was no significant time by group interaction, and no significant effect of group, but there was a significant effect of time for maximal voluntary isometric contraction (primary outcome) (MD=22 Nm/kg; 95%CI: 3.9, 40) and for squat jump (MD=1.6 cm; 95CI%: 0.7, 2.5). There was no significant interaction (time*group), time, or group effect for the other outcomes. Conclusion The addition of PBM to a combined training performed for 6 weeks in previously trained individuals did not result in additional benefits compared to placebo or no additional intervention.
Article
Background Severe burns lead to decreased pulmonary function and impaired aerobic capacity for long periods post-injury. Low-level laser therapy is a modality utilized to improve aerobic capacity, enhance exercise performance and increase time until fatigue when utilized before aerobic exercises. Purpose This work aims to determine the impacts of pre-exercise low-level laser therapy on aerobic capacity in burn cases. Participants and Methods Sixty adults burned cases of both sexes, aged from 25 to 40 years, with second-degree healed thermal burns, and the total burned body surface area ranged from 20 to 40% participated in this study after complete wound healing. They were randomly categorized into two groups of equal numbers. The study group received low-level laser therapy before aerobic exercises, three sessions/week for 12 weeks, while the control group performed aerobic exercises three times weekly for 12 weeks. All cases received the routine physical treatment program. Aerobic capacity was assessed for both groups by measuring maximum oxygen consumption and time to exhaustion at baseline and twelve weeks following interventions. Findings There was a statistically significant rise in the mean values of maximum oxygen usage and time to fatigue after 12 weeks of treatment in both groups. However, after comparison, the improvements in the study group were statistically significant than those in the control group with (p < 0.01), (p < 0.05) respectively. Conclusion Low-level laser therapy has a beneficial therapeutic impact on promoting aerobic capacity, improving maximum oxygen consumption, and increasing treadmill time in burned cases when preceding aerobic exercises.
Article
This study evaluated the effect of photobiomodulation therapy (PBMt) before or after a high-intensity resistance exercise (RE) session on muscle oxidative stress. Female Wistar rats were assigned to one of the following groups: Sham (non-exercised, undergoing placebo-PBMt); NLRE (exercised, undergoing placebo-PBMt); PBMt + RE (pre-exercise PBMt); RE + PBMt (post-exercise PBMt). The RE comprised four climbs bearing the maximum load with a 2 min rest between each climb. An 830-nm aluminum gallium arsenide diode laser (100 mW; 0.028 cm2; 3.57 mW/cm2; 142.8 J/cm2; 4 J; Photon Laser III, DMC, São Paulo, Brazil) was applied 60 s before or after RE in gastrocnemius muscles. Analyses were performed at 24 h after RE: lipoperoxidation using malondialdehyde (MDA) and protein oxidation (OP) on Western blot. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activity were spectrophotometrically assessed. Nitric oxide (NO) level was determined by the Griess reaction. The MDA and OP levels were significantly higher in the NLRE group. Increased OP was prevented in all PBMt groups; however, increased MDA was prevented only in the RE + PBMT group. The RE + PBMt group had higher SOD activity compared to all other groups. A higher GPx activity was observed only in the PBMT + RE compared to Sham group, and CAT activity was reduced by RE, without PBMt effect. NO levels were unchanged with RE or PBMt. Therefore, PBMt application after a RE section has a more potent antioxidant effect than previous PBMt. Rats submitted to post-RE PBMt illustrated prevention of increased lipoperoxidation and protein oxidation as well as increased SOD activity.Graphic abstract The photobiomodulation can attenuate oxidative stress induced by resistance exercise. A more evident benefit shows to be obtained with the application after exercise, in which it has increased the activity of superoxide dismustase.
Article
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Background The optimal time-response window for photobiomodulation therapy (PBMT) using low-level laser therapy (LLLT) and/or light emitting diodes therapy (LEDT) combined with static magnetic fields (sMF) before physical activity still was not fully investigated. The aim of the present study was to investigate the better of four time-response windows for PBMT combined with sMF (PBMT-sMF) use before exercise in humans. Methods A prospectively registered, randomized, triple-blinded (volunteers, therapists and assessors) placebo-controlled trial was carried out. Sixty healthy untrained male subjects were randomly allocated to six experimental groups (n = 10 per group): PBMT-sMF 5 mins, PBMT-sMF 3 h, PBMT-sMF 6 h, PBMT-sMF 1-day, placebo, and control. The control group performed all procedures, however did not receive any kind of intervention. PBMT-sMF active or PBMT-sMF placebo was applied precisely in different time points after baseline MVC test to ensure that both MVC tests and eccentric exercise protocol would occur at the same hour of the day in all groups. Then, after five minutes, 3 h, 6 h or 1-day (24 h) of PBMT-sMF treatment (active or placebo) the eccentric exercise protocol was performed. The primary outcome was peak torque obtained from maximum voluntary contraction (MVC). The secondary outcomes were creatine kinase (CK), and delayed onset muscle soreness (DOMS). The primary and secondary outcomes were measured at baseline, immediately after, 1 h, 24 h and 48 h after the eccentric exercise protocol. Results Sixty patients were randomized and analyzed to each sequence. The outcomes in absolute values show that all active PBMT-sMF groups increased (p < 0.05) MVC from immediately after to 1 h after eccentric exercise, and decreased (p < 0.05) CK activity at all time points. However, PBMT-sMF 5 mins, 3 h and 6 h groups showed better results in MVC and CK analysis from 24 h to 48 h, and also to DOMS (p < 0.05) at all time points. Participants did not report any adverse events. Conclusions PBMT-sMF can be used from 5 min to 6 h before exercise, and the effects can last up to 54 h after treatment. However, the effects start to decrease when a 1-day (24 h) time-response window is used. Trial registration NCT03420391. Registered 05 February 2018.
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Background: The direct application of photobiomodulation therapy (PBMT) using low-level laser therapy (LLLT) and light emitting diodes (LEDs) combined with a static magnetic field (sMF) (PBMT-sMF) to target tissues is shown to improve muscle performance and recovery. Studies have reported possible PBMT effects when a local distant to the target tissue is irradiated. Notably, the extent of these effects on musculoskeletal performance and the optimal site of irradiation remain unclear, although this information is clinically important since these aspects could directly affect the magnitude of the effect. Therefore, we investigated the effects of local and non-local PBMT-sMF irradiations on musculoskeletal performance and post-exercise recovery before an eccentric exercise protocol. Methods: This randomized, triple-blind (participants, therapists and assessors), placebo-controlled trial included 30 healthy male volunteers randomly assigned to the placebo, local, and non-local groups. Active or placebo PBMT-sMF was applied to 6 sites of the quadriceps muscle of both legs. An eccentric exercise protocol was used to induce fatigue. The primary outcome was peak torque assessed by maximal voluntary contraction (MVC). The secondary outcomes were delayed onset muscle soreness (DOMS) measured by visual analogue scale (VAS), muscle injury assessed by serum creatine kinase activity (CK), and blood lactate levels. Evaluations were performed before the eccentric exercise protocol (baseline), as well as immediately after and 1, 24, 48, and 72 h upon protocol completion. Results: Ten volunteers were randomized per group and analysed for all outcomes. Compared to the placebo and non-local groups, irradiation with PBMT-SMF led to statistically significant improvement (p < 0.05) with regard to all variables in the local group. The outcomes observed in the non-local group were similar to those in the placebo group with regard to all variables.The volunteers did not report any adverse effects. Conclusion: Our results support the current evidence that local irradiation of all exercised muscles promotes ergogenic effects. PBMT-sMF improved performance and reduced muscle fatigue only when applied locally to muscles involved in physical activity. Trial registration: NCT03695458. Registered October 04th 2018.
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Background: Photobiomodulation therapy (PBMT) has recently been used to alleviate postexercise muscle fatigue and enhance recovery, demonstrating positive results. A previous study by our research group demonstrated the optimal dose for an infrared wavelength (810 nm), but the outcomes could be optimized further with the determination of the optimal output power. Objective: The aim of the present study was to evaluate the effects of PBMT (through low-level laser therapy) on postexercise skeletal muscle recovery and identify the best output power. Materials and methods: A randomized, placebo-controlled double-blind clinical trial was conducted with the participation of 28 high-level soccer players. PBMT was applied before the eccentric contraction protocol with a cluster with five diodes, 810 nm, dose of 10 J, and output power of 100, 200, 400 mW per diode or placebo at six sites of knee extensors. Maximum isometric voluntary contraction (MIVC), delayed onset muscle soreness (DOMS) and biochemical markers related to muscle damage (creatine kinase and lactate dehydrogenase), inflammation (IL-1β, IL-6, and TNF-α), and oxidative stress (catalase, superoxide dismutase, carbonylated proteins, and thiobarbituric acid) were evaluated before isokinetic exercise, as well as at 1 min and at 1, 24, 48, 72, and 96 h, after the eccentric contraction protocol. Results: PBMT increased MIVC and decreased DOMS and levels of biochemical markers (p < 0.05) with the power output of 100 and 200 mW, with better results for the power output of 100 mW. Conclusions: PBMT with 100 mW power output per diode (500 mW total) before exercise achieves best outcomes in enhancing muscular performance and postexercise recovery. Another time it has been demonstrated that more power output is not necessarily better.
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Researches have been performed to investigate the effects of phototherapy on improving performance and reduction of muscular fatigue. However, a great variability in the light parameters and protocols of the trials are a concern to establish the efficacy of this therapy to be used in sports or clinic. The aim of this study is to investigate the effectiveness, moment of application of phototherapy within an exercise protocol, and which are the parameters optimally effective for the improvement of muscular performance and the reduction of muscular fatigue in healthy people. Systematic searches of PubMed, PEDro, Cochrane Library, EMBASE, and Web of Science databases were conducted for randomized clinical trials to March 2017. Analyses of risk of bias and quality of evidence of the included trials were performed, and authors were contacted to obtain any missing or unclear information. We included 39 trials (861 participants). Data were reported descriptively through tables, and 28 trials were included in meta-analysis comparing outcomes to placebo. Meta-analysis was performed for the variables: time until reach exhaustion, number of repetitions, isometric peak torque, and blood lactate levels showing a very low to moderate quality of evidence and some effect in favor to phototherapy. Further investigation is required due the lack of methodological quality, small sample size, great variability of exercise protocols, and phototherapy parameters. In general, positive results were found using both low-level laser therapy and light-emitting diode therapy or combination of both in a wavelength range from 655 to 950 nm. Most of positive results were observed with an energy dose range from 20 to 60 J for small muscular groups and 60 to 300 J for large muscular groups and maximal power output of 200 mW per diode.
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Cryotherapy for post-exercise recovery remains widely used despite the lack of quality evidence. Photobiomodulation therapy (PBMT) studies (with both low-level laser therapy and light-emitting diode therapy) have demonstrated positive scientific evidence to suggest its use. The study aims to evaluate PBMT and cryotherapy as a single or combined treatment on skeletal muscle recovery after eccentric contractions of knee extensors. Fifty healthy male volunteers were recruited and randomized into five groups (PBMT, cryotherapy, cryotherapy + PBMT, PMBT + cryotherapy, or placebo) for a randomized, double-blinded, placebo-controlled trial that evaluated exercise performance (maximum voluntary contraction (MVC)), delayed onset muscle soreness (DOMS), and muscle damage (creatine kinase (CK)). Assessments were performed at baseline; immediately after; and at 1, 24, 48, 72, and 96 h. Comparator treatments was performed 3 min after exercise and repeated at 24, 48, and 72 h. PBMT was applied employing a cordless, portable GameDay™ device (combination of 905 nm super-pulsed laser and 875- and 640-nm light-emitting diodes (LEDs); manufactured by Multi Radiance Medical™, Solon - OH, USA), and cryotherapy by flexible rubber ice packs. PBMT alone was optimal for post-exercise recovery with improved MVC, decreased DOMS, and CK activity (p < 0.05) from 24 to 96 h compared to placebo, cryotherapy, and cryotherapy + PBMT. In the PBMT + cryotherapy group, the effect of PBMT was decreased (p > 0.05) but demonstrated significant improvement in MVC, decreased DOMS, and CK activity (p < 0.05). Cryotherapy as single treatment and cryotherapy + PBMT were similar to placebo (p > 0.05). We conclude that PBMT used as single treatment is the best modality for enhancement of post-exercise restitution, leading to complete recovery to baseline levels from 24 h after high-intensity eccentric contractions.
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Aim: This study aimed to evaluate the medium-term effects of low-level laser therapy (LLLT or photobiomodulation) in postexercise skeletal muscle recovery and performance enhancement and to identify the optimal dose of 810 nm LLLT. Materials and methods: A randomized, double-blind, placebo-controlled trial was performed, with voluntary participation of 28 high-level soccer athletes. We analyzed maximum voluntary contraction (MVC), delayed onset muscle soreness (DOMS), creatine kinase (CK) activity, and interleukin-6 (IL-6) expression. The assessments were performed before exercise protocols, after 1 min, and 1, 24, 48, 72, and 96 h after the end of eccentric exercise protocol used to induce fatigue. LLLT was applied before eccentric exercise protocol with a cluster with five diodes, and dose of 10, 30, or 50 J (200 mW and 810 nm) in six sites of quadriceps. Results: LLLT increased (p < 0.05) MVC from immediately after exercise to 24 h with 50 J dose, and from 24 to 96 h with 10 J dose. Both 10 J then 50 J dose decreased (p < 0.05) CK and IL-6 with better results in favor of 50 J dose. However, LLLT had no effect in decreasing DOMS. No differences (p > 0.05) were found for 30 J dose in any of the outcomes measured. Conclusion: Pre-exercise LLLT, mainly with 50 J dose, significantly increases performance and improves biochemical markers related to skeletal muscle damage and inflammation.
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The effects of phototherapy (or photobiomodulation therapy) with low-level laser therapy (LLLT) and/or light-emitting diodes (LEDs) on human performance improvement have been widely studied. Few studies have examined its effect on muscular training and no studies have explored the necessary moment of phototherapy irradiations (i.e., before and/or after training sessions). The aim of this study was to determine the optimal moment to apply phototherapy irradiation when used in association with strength training. Forty-eight male volunteers (age between 18 to 35 years old) completed all procedures in this study. Volunteers performed the strength training protocol where either a phototherapy and/or placebo before and/or after each training session was performed using cluster probes with four laser diodes of 905 nm, four LEDs of 875 nm, and four LEDs of 640 nm—manufactured by Multi Radiance Medical™. The training protocol duration was 12 weeks with assessments of peak torque reached in maximum voluntary contraction test (MVC), load in 1-repetition maximum test (1-RM) and thigh circumference (perimetry) at larger cross-sectional area (CSA) at baseline, 4 weeks, 8 weeks, and 12 weeks. Volunteers from group treated with phototherapy before and placebo after training sessions showed significant (p < 0.05) changes in MVC and 1-RM tests for both exercises (leg extension and leg press) when compared to other groups. With an apparent lack of side effects and safety due to no thermal damage to the tissue, we conclude that the application of phototherapy yields enhanced strength gains when it is applied before exercise. The application may have additional beneficial value in post-injury rehabilitation where strength improvements are needed.
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Context: Recent studies suggest the prophylactic use of low-powered laser/light has ergogenic effects on athletic performance and postactivity recovery. Manufacturers of high-powered lasers/light devices claim that these can produce the same clinical benefits with increased power and decreased irradiation time; however, research with high-powered lasers is lacking. Objective: To evaluate the magnitude of observed phototherapeutic effects with 3 commercially available devices. Design: Randomized double-blind placebo-controlled study. Setting: Laboratory. Patients or other participants: Forty healthy untrained male participants. Intervention(s): Participants were randomized into 4 groups: placebo, high-powered continuous laser/light, low-powered continuous laser/light, or low-powered pulsed laser/light (comprising both lasers and light-emitting diodes). A single dose of 180 J or placebo was applied to the quadriceps. Main outcome measure(s): Maximum voluntary contraction, delayed-onset muscle soreness (DOMS), and creatine kinase (CK) activity from baseline to 96 hours after the eccentric exercise protocol. Results: Maximum voluntary contraction was maintained in the low-powered pulsed laser/light group compared with placebo and high-powered continuous laser/light groups in all time points (P < .05). Low-powered pulsed laser/light demonstrated less DOMS than all groups at all time points (P < .05). High-powered continuous laser/light did not demonstrate any positive effects on maximum voluntary contraction, CK activity, or DOMS compared with any group at any time point. Creatine kinase activity was decreased in low-powered pulsed laser/light compared with placebo (P < .05) and high-powered continuous laser/light (P < .05) at all time points. High-powered continuous laser/light resulted in increased CK activity compared with placebo from 1 to 24 hours (P < .05). Conclusions: Low-powered pulsed laser/light demonstrated better results than either low-powered continuous laser/light or high-powered continuous laser/light in all outcome measures when compared with placebo. The increase in CK activity using the high-powered continuous laser/light compared with placebo warrants further research to investigate its effect on other factors related to muscle damage.
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While growing evidence supports the use of photobiomodulation therapy (PBMT) for performance and recovery enhancement, there have only been laboratory-controlled studies. Therefore, the aim of this study was to analyze the effects of PBMT in performance and recovery of high-level rugby players during an anaerobic field test. Twelve male high-level rugby athletes were recruited in this randomized, crossover, double-blinded, placebo-controlled trial. No interventions were performed before the Bangsbo Sprint Test (BST) at familiarization phase (week 1), at weeks 2 and 3 pre-exercise PBMT or placebo were randomly applied to each athlete. PBMT irradiation was performed at 17 sites of each lower limb, employing a cluster with 12 diodes (4 laser diodes of 905nm, 4 LED diodes of 875nm, and 4 LED diodes of 640nm, 30J per site - manufactured by Multi Radiance Medical™). Average time of sprints, best time of sprints, and fatigue index were obtained from BST. Blood lactate levels were assessed at baseline, and at 3, 10, 30 and 60 minutes after BST. Athletes' perceived fatigue was also assessed through a questionnaire. PBMT significantly (p<0.05) improved average time of sprints and fatigue index in BST. PBMT significantly decreased percentage of change in blood lactate levels (p<0.05) and perceived fatigue (p<0.05). Pre-exercise PBMT with the combination of super-pulsed laser (low-level laser), red and infrared LEDs can enhance performance and accelerate recovery of high-level rugby players in field test. This opens a new avenue for wide use of PBMT in real clinical practice in sports settings.
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Context: Skeletal muscle fatigue and exercise performance are novel areas of research and clinical application in the photobiomodulation field, and positive outcomes have been reported in several studies; however, the optimal measures have not been fully established. Objective: To assess the acute effect of photobiomodulation therapy (PBMT) combining superpulsed lasers (low-level laser therapy) and light-emitting diodes (LEDs) on muscle performance during a progressive cardiopulmonary treadmill exercise test. Design: Crossover study. Setting: Laboratory. Patients or other participants: Twenty untrained male volunteers (age = 26.0 ± 6.0 years, height = 175.0 ± 10.0 cm, mass = 74.8 ± 10.9 kg). Intervention(s): Participants received PBMT with either combined superpulsed lasers and LED (active PBMT) or placebo at session 1 and the other treatment at session 2. All participants completed a cardiopulmonary test on a treadmill after each treatment. For active PBMT, we performed the irradiation at 17 sites on each lower limb (9 on the quadriceps, 6 on the hamstrings, and 2 on the gastrocnemius muscles), using a cluster with 12 diodes (four 905-nm superpulsed laser diodes with an average power of 0.3125 mW, peak power of 12.5 W for each diode, and frequency of 250 Hz; four 875-nm infrared LED diodes with an average power of 17.5 mW; and four 640-nm red LED diodes with an average power of 15 mW) and delivering a dose of 30 J per site. Main outcome measure(s): Distance covered, time until exhaustion, pulmonary ventilation, and dyspnea score. Results: The distance covered (1.96 ± 0.30 versus 1.84 ± 0.40 km, t19 = 2.119, P < .001) and time until exhaustion of the cardiopulmonary test (780.2 ± 91.0 versus 742.1 ± 94.0 seconds, t19 = 3.028, P < .001) was greater after active PBMT than after placebo. Pulmonary ventilation was greater (76.4 ± 21.9 versus 74.3 ± 19.8 L/min, t19 = 0.180, P = .004) and the score for dyspnea was lower (3.0 [0.5-9.0] versus 4.0 [0.0-9.0], U = 184.000, P < .001) after active PBMT than after placebo. Conclusions: The combination of lasers and LEDs increased the time, distance, and pulmonary ventilation and decreased the score of dyspnea during a cardiopulmonary test.
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Patients with COPD suffer from lower-limb muscle dysfunction characterized by lower muscle oxidative capacity and muscle mass. Exercise-based training is expected to attenuate lower-limb intramuscular characteristics, but a detailed systematic approach to review the available evidence has not been performed yet. PUBMED and PEDro databases were searched. Twenty-five studies that implemented an exercise-based training program (aerobic and/or resistance training, high intensity interval training, electrical or magnetic stimulation) and reported muscle biopsy data of patients with COPD were critically appraised. The coverage of results includes changes in muscle structure, muscle protein turnover regulation, mitochondrial enzyme activity, oxidative and nitrosative stress, and inflammation after exercise-based training interventions. Study design and training modalities varied among studies, which partly explains the observed heterogeneous response in muscle characteristics. Gaps in the current knowledge are identified and recommendations for future research are made to enhance our knowledge on exercise training effects in patients with COPD.