Effects of the infrared lamp illumination during the process of muscle fatigue in rats

Abstract

In this study the effects of infrared lamp illumination during the muscle fatigue process was studied. Three different groups (n=5) were used: one control group and two treated ( Infrared Lamp 780- 1400nm), with the energy densities of 0.5 and 1.0 J/cm 2 and time of illumination of 300 seconds. The treated animals were illuminated in one point directly in the tibiali s muscle, after the first tetanic contraction out of six, with an interval between each tetany. The results were registered in an electrophysiograph and the intensity of the force of contraction in grams w as analysed. It was observed that the control group presented a reduction in the intensity of the force of contraction, while the treated group managed to maintain it, which was clearly evident in the energy density of 0.5 J/cm 2. It was concluded that the use of the infrared lamp illumination was efficient c oncerning resistance to muscle fatigue.

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403
Brazilian Archives of Biology and Technology
Vol.50, n. 3 : pp.403-407 May 2007
ISSN 1516-8913 Printed in Brazil BRAZILIAN ARCHIVES OF
BIOLOGY AND TECHNOLOGY
A N I N T E R N A T I O N A L J O U R N A L
Effects of the Infrared Lamp Illumination during the
Process of Muscle Fatigue in Rats
Andréia Zarzour Abou-Hala1, Daniella Galvão Barbosa2, Rodrigo Labat Marcos3, Cristina
Pacheco-Soares1 and Newton Soares da Silva1*
1Laboratório de Biologia Celular e Tecidual; 2Laboratório de Fluorescência; 3Laboratório de Fisiologia e
Farmacodinâmica; Instituto de Pesquisa e Desenvolvimento; Universidade do Vale do Paraíba - UNIVAP; Av.
Shishima Hifumi, 2911; nsoares@univap.br; 12244-000; São José dos Campos - SP - Brasil
ABSTRACT
In this study the effects of infrared lamp illumination during the muscle fatigue process was studied.
Three different groups (n=5) were used: one control group and two treated (Infrared Lamp 780-
1400nm), with the energy densities of 0.5 and 1.0 J/cm2 and time of illumination of 300 seconds. The
treated animals were illuminated in one point directly in the tibialis muscle, after the first tetanic
contraction out of six, with an interval between each tetany. The results were registered in an
electrophysiograph and the intensity of the force of contraction in grams was analysed. It was observed
that the control group presented a reduction in the intensity of the force of contraction, while the treated
group managed to maintain it, which was clearly evident in the energy density of 0.5 J/cm2. It was
concluded that the use of the infrared lamp illumination was efficient concerning resistance to muscle
fatigue.
Key words: Muscle fatigue; infrared illumination; muscle tension; tetany
* author for correspondence
INTRODUCTION
Muscle fatigue can be defined as the group of
manifestations produced by work or prolonged
exercise. The consequence will be the reduction in
maintaining or continuing the expected result
(Rossi, 1999; Schwid, 2002). Muscle fatigue may
alter muscle functioning due to the exhaustion of
mediators at several levels, which can establish a
muscular unbalance, making easier the appearance
of lesions (Fitts, 1996). Possible causes of the
muscle fatigue can be failure of the motor nerve,
the neuromuscular junction, the central nervous
system and also the contractile mechanism, in
which fatigue takes place due to the depletion of
the adenosine triphosphate and muscular glycogen
stock and the large amount of lactic acid (Fox et
al., 1991; Thomas et al., 2003). Muscle fatigue
may be the result of impairments at any of a
number of sites within the neuromuscular system,
which manifests as a decline in the maximum
force-generating capacity of the muscle (Fulco
at al., 2001; Allman and Rice, 2002).
The skeletal muscle, when exposed to intense and
continuous effort, tends to lose its contractile
capacity. This occurs because during the
contraction, the intramuscular pressure exceeds the
blood pressure, obliterating small nutrition vessels
and the oxygen flow as well. The muscle cells
obtain energy through the anaerobic glycolysis in

Abou-Hala, A. Z. et al.
Brazilian Archives of Biology and Technology
404
which the metabolic result is the lactic acid.
Clinically, this phenomenon is interpreted as
contractures and reduction of the muscular
functional capacity, due to decrease in the peak
tension and power (Fitts, 1996).
The use of infrared (IR) radiation in the treatment
of a variety of medical conditions has been studied
for a long time. The IR radiation is applied in the
inner part of the electromagnetic spectrum which
generates heat when absorbed by matter (Kitchen
and Partridge, 1991; Gul and O'Sullivan, 2005).
According to Moss et al. (1989), many sources
which emit either visible or ultraviolet radiation
will also emit IR and this IR radiation have
different refractive indices and different reflection,
transmission and scattering characteristics,
depending on the wavelength of the light. Infrared
radiation in the IR-B (medium infrared: 1.4 - 3µm)
and IR-C (long infrared: 3µm - 1mm) ranges is
absorbed in the top layers of the skin. The shorter-
wavelength IR-A radiation (780 - 1400ηm) has a
greater penetrating power. The IR lamp, a non-
coherent irradiation, has a wavelength spectrum
with a pronounced peak approximately 1000ηm in
the deep-penetrating IR-A range. All of these
patterns are quite important when measuring IR
radiations but only the reflection and absorption
are extremely meaningful biologically and
clinically since they have been considered effects
of IR radiation on tissues.
The investigation into the effect of the IR lamp
illumination during the process of muscle fatigue
in tibialis anterior muscle of rats was the main goal
of this study.
MATERIALS AND METHODS
In this study the ethical principles of animal
experimentation was applied in conformity to
COBEA (Brazilian School of Experimentation
Animal), having been approved by the Committee
of Ethics in Research of UniVap, Protocol n°
L007/2003/CEP. Fifteen (15) male Wistar rats
were used, weighing between 250 and 300g.
During the experiment, the animals were housed
under standard conditions in cages, five animals
per cage and kept under constant conditions of
temperature (22±2°C) with a 12-h light/12-h dark
cycle. The rats were fed with ad libitum and
supplied with drinking water.
All surgical procedures were performed under
aseptic conditions. Each animal was pre-
anesthetized with Butorfanol (Torbugesic), in
the dose of 2 mg/Kg via intramuscular (Flecknell,
1996). After 15 minutes, the rat was sedated with
chloral hydrate (i.p.), in the dose of 420mg/kg in a
10% solution (Almaguer-Melián et al., 1999) and
placed on a surgical table where it was carried
through the withdrawal of the skin and dissecation
of the muscle previous tibial with the purpose to
isolate the nerve fibular deep (responsible for the
stimulation of the muscle) isolated the nerve, in
the region of the insertion next to the plantar to
metatarsus region, the muscle (through the tendon)
was connected to an isometric transducer (Ugo
Basile®; Vareze, Italy) that it transforms the data
of muscle tension into electric signals transmitted
to the electrophysiograph and the nerve connected
to a bipolar electrode, on to the eletrostimulator,
for indirect inervation of the muscle.
The muscle was exposed to a constant tension of
10g. The muscle was stimulated indirectly by
pulses of 7 V, 0.2Hz for 2 miliseconds. The
muscle and tetanics contractions in response to the
indirect stimulations were registered in a
physiograph (GEMINI 7070 of UGO BASILE®)
through the isometric transducer for approximately
60 minutes. To stimulate the tetanic contraction,
the frequency was raised to 60 Hz, every 10
minutes, out of six contractions (Marcos, 2002;
Lopes-Martins et al., 2006). During the whole
experiment, the muscle was dampened with a
sterile saline solution (0.9%) to prevent drying.
The muscle fatigue was determined by the
incapacity to keep the muscle contraction.
Therefore, there would be a decline of the
amplitude in 50% maximum contraction muscle
recorded, to prevent the death of the tissue because
of the tetanic contraction.
The animals were divided in three groups, which
were:
1) Control group: not radiated, with stimulation of
6 tetanic contractions;
2) Infrared Lamp Illumination, energy density of
0.5J/cm2;
3) Infrared Lamp Illumination, energy density of
1.0J/cm2.
A PHILIPS® lamp - Infrared 780-1400nm (Fig. 1)
was used. The treated animals were illuminated in
one point after the stimulation of the first tetanic
contraction, directly in the tibialis muscle exposed
at that moment. The patterns of each protocol are
indicated in table 1.
At the end of each experiment the animals were
killed with excessive intracardiac dose of Sodium

Effects of the Infrared Lamp Illumination during the Process of Muscle Fatigue in Rats
Brazilian Archives of Biology and Technology
405
Thiopental (Thiopentax®), 60mg/kg (Thurmon,
1999). The data obtained were analyzed
statistically by the test of variance analysis to 5%
of probability (ANOVA). The average and the
standard error (s.e.) of the average was calculated
and the difference among the data of the control
group and irradiated was determined by the Tukey
test. Significant values were considered
statistically with p< 0.05, p<0.01 and p<0.001.
Figure 1 - Esquematic drawing of the assembly of the box: (1) Infrared Lamp (Philips®), (2)
Wooden Pinhole (Ø 5mm), (3) Lens (CSR® - Ø 50mm 6x) and (4) Filters
Table 1 - Protocol of IR irradiation
Parameters of irradiation Values Values
Energy density 0.5 J/cm2 1 J/cm2
Potency 0.5 mW 1 mW
Wavelength 780-1400 nm 780-1400 nm
Area 0.3 cm2 0.3 cm2
Time 300 seconds 300 seconds
RESULTS
The results of the intensity of the force of
contraction measured in each electric stimulation,
after tetany were analyzed (Fig. 2). It was
observed that in the control group a decrease in the
muscle tension (intensity of the muscle force)
occurred during the tetanic contractions and this
reduction was even better observed by a fall after
the first tetanic contraction.
In the treated group with energy density of
0.5J/cm2, a significant fall was not observed. In the
treated group with energy density of 1.0J/cm2, a
significant fall was observed after the third tetanic
contraction, being more highlighted from the
fourth contraction on.
In the animals of the control group, the most
significant fall of 26.7% was observed. The treated
group with 0.5J/cm2 presented a fall of 6.0%
(lesser fall) and the treated group of 1.0 J/cm2
presented a fall of 14.5%.

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406
123456
13
14
15
16
17
18
19
***
***
*
*
**
**
*
**
** Control
0.5J/cm2
1.0J/cm2
Muscular tension during tetanic contraction (g)
Number of tetanic contraction
Group 1 2 3 4 5 6
Control 18.4 17.1±0.1278 16.3±0.2556 15.5±0.1826 14.5±0.3034 13.2±0.1258
0.5J/cm2 18.4 18.8±0.3452 18.0±0.2154 17.4±0.4169 17.0±0.3262 16.9±0.2880
1.0J/cm2 18.4 18.1±0.3475 17.4±0.2909 16.8±0.2733 15.9±0.4264 15.4±0.4992
Figure 2 - Intensity of the muscle contraction force by tetanic contractions (mean± se) (* p< 0.05,
** p<0.01 and *** p<0.001)
DISCUSSION
This study has investigated, through the IR lamp
illumination, the reduction of the muscle fatigue in
tibialis anterior muscle of rats after stimulation of
tetanic contractions by indirect electrical stimulus.
By using the IR lamp illumination with energy
densities of 0.5 and 1.0 J/cm2, it was possible to
observe a reduction in the intensity of the force of
contraction of 6.0 and 14.5%, respectively; both
being less than the control group (26.7%). High
levels of certain metabolites in the blood, due to
the increased metabolic activity arising from the
high temperatures, have a direct effect on vessel
walls, stimulating vasodilation (Ward, 1986; Wells
et al., 1988; Ganong, 1989). According to
Massuda et al. (2005), the high rate of metabolism
due to increased body temperature and increased
blood flow, decreased subjective symptoms,
resulting in increased energy scores, hence
promoting a better resistance related to muscular
fatigue.
Although has been proved that the use of the IR
lamp illumination improve the resistance, further
studies should be done in order to determine such
effects, clearly showing that the treatment with the
IR lamp illumination was efficient.
CONCLUSION
It could be concluded that the use of the IR lamp
illumination with energy density of 0.5 J/cm2
promoted more resistance to the muscle fatigue.
ACKNOWLEDGEMENTS
We are grateful to Chaker Nayef Abou Hala and
Ana Paula Marques de Mendonça Lopes for
technical assistance, and Renato Amaro Zângaro,
PhD (Laboratório de Fluorescência).
RESUMO
Neste estudo investigamos o efeito da irradiação
da lâmpada infravermelha durante o processo de
fadiga muscular. Foram utilizados 3 grupos
diferentes (n=5), sendo 1 grupo controle e 2
irradiados (Lâmpada de Infravermelho 780-
1400nm), nas densidades de energia 0,5 e 1,0J/cm2
e tempo de irradiação 300 segundos. Os animais
irradiados receberam 1 irradiação em 1 ponto,
diretamente no músculo tibial, após a primeira
contração tetânica de um total de seis, com um
intervalo entre cada tetania. Os resultados foram
registrados em eletrofisiógrafo e analisado a
intensidade da força de contração em gramas. Foi
observado que o grupo controle apresentou uma

Effects of the Infrared Lamp Illumination during the Process of Muscle Fatigue in Rats
Brazilian Archives of Biology and Technology
407
redução na intensidade da força de contração, já os
grupos irradiados conseguiram mantê-la, sendo
mais evidente quando irradiado com densidade de
energia (DE) de 0,5J/cm2. Conclui-se que a
utilização da irradiação da lâmpada infravermelha
é eficaz na resistência a fadiga muscular.
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Received: November 12, 2004;
Revised: August 12, 2005;
Accepted: March 12, 2007.