Investigation of the Role of 905-nm Laser Light in the Delay of Muscle Fatigue
Condition: Muscle Fatigue
MeSH terms: Fatigue
Study type: Interventional

Summary: 
      800-nm laser light has been shown to delay muscle fatigue when applied before exercise. The
      effect of illumination during the aerobic phase of strenuous exercise has not been studied.
      The investigators hypothesize that the increased energy donated to cells during the aerobic
      phase will significantly delay muscle fatigue. A novel aspect of this study is to include
      simultaneous treatment with near infrared light at 800 nm and 905 nm. Fatigue index and
      change in lactate blood level will be used to compare the different laser treatments for each
      participant. Monte Carlo simulations of light energy reaching the muscle will be carried out,
      based on skin-fold thickness measurements of each participant. The investigators believe this
      will be the first report of optical dosimetry as a function of adipose thickness and it will
      enable estimation how much of the light applied to the skin surface is able to penetrate to
      the muscles that are thought to be affected. The results of this study will help clinicians
      to optimize treatment for individual patients.
    

Detailed description: 
      Rationale, Objectives and Significance A recent study has shown that low intensity Near
      Infrared (NIR) light at 810 nm applied before exercise results in an increase in performance
      and decrease in oxidative stress and muscle damage (1). Another study by the same group with
      830 nm light showed a delay in exercise-induced muscle fatigue when applied before exercise
      (2). A number of studies have shown varying results with near infrared light for pain relief,
      inflammation and wound healing. The results often vary in part due to the difference in the
      wavelength and intensity of the light source and variation in the depth of penetration of the
      light. Red and NIR light is known to penetrate significantly into biological tissues. For
      example, a recent study presents qualitative evidence that 830 nm light penetrated
      significantly through cadaver soft tissue and a human hand in vivo (3). The optical
      properties of various human tissues have been studied at 800 to 950 nm so it is possible for
      the investigators to calculate the precise distribution of near infrared light in relation to
      the physiological effects. The investigators are well equipped to carry this out with an
      original, calibrated Monte Carlo program. The mechanism of action for low intensity red to
      NIR light has been fairly well studied and is thought to occur through absorption of the
      light by mitochondrial cytochrome c oxidase which leads to energy production in the
      illuminated cells (4). The effect of illumination DURING the aerobic phase of strenuous
      exercise has not been studied. The investigators hypothesize that the increased energy
      donated to cells during the aerobic phase will significantly delay muscle fatigue.

      fatigue index and lactate blood level will be used to compare the different laser treatments.
      Another novel aspect of this study is to include NIR light at 905 nm. A hypothesized
      mechanism for delay of muscle fatigue is a light-initiated release of oxygen from hemoglobin
      molecules by 905-nm laser light, resulting in increased oxygenation of the local tissue. The
      laser may heat the tissue slightly so it is not clear whether oxygen release is due to a
      thermal or photochemical mechanism. A recent study of low level light (660 nm, 350 mW, 15
      minutes) resulted in no measurable change in local tissue oxygenation for healthy
      participants (5). Another recent study with a more intense light source (K-laser at 800, 907
      and 970 nm, 3 W, 4 minutes) demonstrated increased blood flow in the upper arm following
      irradiation with the NIR laser (6). However the authors did not measure the temperature of
      the irradiated tissue.

      In the proposed study the investigators will keep the intensity of 800 nm light constant in
      all of the trials. The proposed study will include collection of surface temperature during
      the treatment to begin to document whether tissue heating is involved in the mechanism. The
      adipose thickness (calculated from skin fold thickness) will be used with the Monte Carlo
      simulation to calculate the fraction of light that is expected to reach the muscle for each
      participant. This will be the first report of optical dosimetry as a function of adipose
      thickness and it will enable estimation of how much of the light applied to the skin surface
      is able to penetrate to the muscles that are thought to be affected. The results of this
      study will help clinicians to optimize treatment for individual patients.

        1. Thiago de Marchi, Ernesto Cesar Pinto Leal Junior et al, Low level laser therapy (LLLT)
           in human progressive intensity running: effects on exercise performance, skeletal muscle
           status and oxidative stress. (2012) Lasers in Medical Science 27:231236.

        2. Ernesto Cesar Pinto Leal Junior, Rodrigo Alvaro Brandao LopexMartins et al. Effect of
           830nm lowlevel therapy in exercise induced skeletal muscle fatigue in humans. (2009)
           Lasers in Medical Science 24:425431.

        3. Jared Jagdeo, Lauren Adams, et al. Transcranial red and near infrared light transmission
           in a cadaveric model. (2012) PLOS ONE 7:10 e47460

        4. Janis Eells, Margaret WongRiley, et al. Mitochondrial signal transduction in accelerated
           wound and retinal healing by near infrared light therapy. (2004) Mitochondrion Sep;
           4(56):55967.

        5. Franziska Heu, Clemens Forster, Barbara Namer, Adrian Dragu, Werner Lang. Effect of
           lowlevel laser therapy on blood flow and oxygenhemoglobin saturation of the foot skin in
           healthy subjects: a pilot study. (2013) Laser Therapy 22(1): 2130.

        6. Kelly Larkin, Jeffrey Martin, Elizabeth Zeanah, Jerry Tue, Randy Braith, Paul Borsa.
           Limb blood flow after class 4 laser therapy. (2012) Journal of Athletic Training. 47(2):
           178183.
    

Intervention name(s): Control; 800 nm laser; combination laser; 905 nm laser
Intervention type(s): Device; Device; Device; Device
Intervention description(s): laser beam only; 800 nm laser applied to forearm at 4.4 Joules per square cm during 40 hand grips; 800 nm and 905 nm laser applied to forearm at 4.4 Joules per square cm during 40 hand grips; 905 nm laser applied to forearm at 4.4 Joules per square cm during 40 hand grips
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Each participant receives placebo and two different light treatments in random order
Masking: Single (Participant)
Primary purpose: Basic Science
Keywords: Low-Level Light Therapy