Updated: Nov 30, 2021
Today I'm bringing you information about a study done back in 2012 with laser looking at increasing blood flow. But I want to really highlight some of the things that researchers talked about in this study, concerning laser types and the equipment, the protocols, and the settings and the importance of those. I've run into people many times that say, you know, does the power of the laser really matter? Does the technique matter? What about the way you use it ?
Unfortunately there's just not a lot of training available out there for how to properly apply and use laser, which is the main thing that I founded LTI to do; provide good, accurate training and protocols to start to standardize what laser therapy providers are doing so that you can get reproducible and predictable results from laser therapy.
How Does Laser Therapy Work?
First, I want to talk to you about kind of laser mechanisms, just to recap how laser works in the tissues. Then I want to talk to you about class three versus class four lasers, the differences and why they matter. And then after I go through that, then I'll talk you through the methods on this study, and the conclusions they were able to make, so that you can use this information going forward in your practice and also going forward in your decision making about what type of equipment to buy and also what type of training you should be looking for.
Controlling Blood Flow and Swelling is Critical
The study is titled "Limb Blood Flow after Class IV Laser Therapy." This was published in the Journal of Athletic Training in 2012 and by produced by a mixture of chiropractors, PhD researchers, athletic trainers and physical therapists as well, and was headquartered at the university of Florida. So they start off by talking about the ability of laser to produce arteriolar dilation and improved blood flow within the soft tissues in general, they say that laser therapy induced changes in blood flow in microcirculation promote healing by controlling ischemia, hypoxia, and edema after injury, thereby limiting the zone of secondary tissue damage, and the increased circulation in and around the injury zone, not just on the injury, but also around the injury creates a favorable environment for biological repair after musculoskeletal injury.
When you have a sprain/strain injury, swelling is a major component of that, and minimizing swelling is very important. Why? Because the more swelling you have around the injury, the less blood flow actually gets into those tissues. And the more pain is generated. And then the slower this thing heals, that's why controlling swelling is such a big piece in the initial stages of managing a sprain strain injury. You want to use ice. You want to elevate. You want to compress and you want to rest that injured area. Now the newest data shows that we should really only be icing in that first day. And we shouldn't continue icing past that for sprain strain injuries, because it does reduce circulation and that slows down the recovery.
So once you've got the swelling controlled, then you want more circulation. That's exactly what we're talking about with this study. Getting more blood flow to that injured area and around that injured area to maximize the healing capability of the body. It will reduce ischemia. It will reduce hypoxia and it will also reduce edema if you can get laser to and around that injured tissue pretty rapidly after the injury has occurred.
Improving Blood Flow with Laser Therapy
So if we know that the potential is there for laser to increase blood flow to an injured area and nearby improve healing and repair, then the next step is laser dose. Figuring out dose has been somewhat of a controversial issue for the last couple of decades and the researchers in this paper say that achieving that therapeutic dose without under stimulating or overstimulating the target tissues is often the most difficult component of clinical laser therapy practice. If you have the wrong dose, you're not going to get the right level of effect. If your dose is too low, or if it's too high, you either understimulated or overstimulated the area and that can even slow down healing. If you've looked into the science behind light therapy and laser, you'll see a lot of people that talk about the Arndt Schultz principle, which is that idea of overstimulation and under stimulation both being bad and needing to be in the middle of that dose window to accelerate healing, but not overstimulate or under stimulate the tissues.
These researchers go on to say that the idea of optimal therapeutic dosage was originally adapted from a toxicology studies of yeast culture, to look at growth rates and so forth and singles, a single cell layer, and ultimately that's where some of the dose guidelines have come from- looking at tissue cultures and cell layers, and then based on those observations, translating that onto a live tissue model. Live tissues are complex, there are differing tissue volume and different tissue types, different skin colors that affect the way that laser is absorbed, different muscle content, water, content, fat content. Depending on even the region of the body you're working on, even on the same patient, working on a knee is vastly different than working on the low back.
The study goes on to say that several published reports have questioned the ability of low power lasers to effectively transmit energy beyond the skin into deep musculoskeletal tissues. Now, if the skin is your target, you can use low power level and low level lasers very effectively. What these authors are calling into question is, with a low power laser, can you actually get a therapeutic dose into those deep tissues?
Class 3 vs Class 4 lasers
So a class 3 or class 3B laser can go from five to 500 milliwatts, whereas class four lasers will be any lasers that can go over 500 milliwatts. So that means that a one watt older model therapy laser is a class four laser. And so is the laser that the Navy uses on its ships to shoot down drones at more than 50 kilowatts. They're all in the same class. They're all class four. So laser classes don't really give us a really clear idea on heat level or tissue destruction capability or tissue stimulation. It's just a way to indicate the level of power being above that half a watt. This study says that class four lasers can emit greater photonic energy in a shorter period of time than class 3B lasers without producing an appreciable rise in tissue temperature under normal treatment protocols. So if you've heard that class four lasers always damaged tissue, if you've heard that class four lasers are surgical lasers, that simply is not true. If you have a therapy laser it's designed to do laser therapy in that class four range, it is simply delivering more energy in a shorter period of time, but utilizing the same mechanisms of as Class 3 laser to promote increasing blood flow and stimulating better cellular respiration so that you have improved tissue healing. The authors of this study, go on to say that this higher power becomes important when treating injuries to deeper tissues, such as ligaments, muscles, tendon, and cartilage.
The authors in this paper say that beam intensities greater than one watt greatly improve light transmission through soft tissues when compared with lower beam intensities of say, half a watt, therefore class four lasers using beam intensities of greater than one watt may have an advantage or a class three lasers in transmitting light to deeper tissues. What that means is the higher your light's power is, the more it can get into deeper tissues. It's not an exact across the board percentage of light that gets to deeper tissues, it's more of an exponential factor. You get more light in deeper if you start with higher power. There's actually been multiple studies that have shown this fact, whether it is transcranial or just simply getting through the skin barrier to get into those deeper tissues.
There's absolutely value to class 3B lasers. There is absolutely value to LED light therapy, and there's value to class four. Each of them have different things they are better at. In a clinical setting, time is important and so is the capability of reaching deeper tissues, and that is why many, many clinicians have moved to class four lasers.
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These authors applied class four laser to the bicep, and then measured blood flow in the distal forearm. Their hypothesis here was it by lasering the upper portion of the arm, they would actually see changes in blood flow, not where they were lasering, but distal to the place where they applied the laser. They utilized a sham treatment in addition to settings at one watt, six watts, and three watts, all at a 50% duty cycle using a K-laser, and they applied the laser for four minutes to the bicep, taking measurements throughout the treatment, and then also five minutes after the treatment. What they saw is that for the three watt dose, they saw good increases in blood flow, both at minute four of the treatment and then up to two minutes after treatment, that it continued to have improved blood flow to that distal forearm. They did not observe any changes in blood flow for the six watt or one watt settings, and of course did not see any for these sham doses before, during or after laser treatment either.
Laser Therapy Settings and Protocols
So even though they were using the same equipment, the same time and the same treatment location, just changing the power settings, had a massive difference on improving blood flow down the arm. If they went too high, they didn't see any improved blood flow down into the rest of the limb. If they went too low, they didn't see any improved blood flow to the rest of the limb. They had to be in that sweet spot. You to have the right dosing. So they conclude by saying that a properly designed laser treatment protocol with appropriate dosing guidelines is a viable therapy to increase limb blood flow. But what they didn't say is the wrong treatment protocol or the wrong dosing will do you really no good. And that I think is really one of the big takeaways here. Laser is a great modality for improving blood flow and for soft tissue healing. But more than that, you have to have the right equipment that can give you the right level of dosing. You need to have the right settings, you need the right protocols. If you don't have all that correct, then in clinical practice, you're just not going to see the results that you should. If you're using a laser that's too weak or that is under powered, if your settings aren't adapted to the effects you want to see in the tissue, if the protocols you're using have you treated in the wrong place or for the wrong amount of time, you're just not going to see those reproducible predictable results. And when it comes to clinical practice, that's incredibly frustrating because what you do with one patient that works may not work with another patient.
Custom Laser Settings and Treatment Plans
That is why Laser Therapy Institute exists; is to provide protocols that give you these producible, reproducible, and predictable results in clinic. That means you need the custom protocols that give you the right response in the tissues. You need to have the education on how to pick the correct dose, the correct time, the correct power settings, and even where to treat. Let us help you get the right settings and protocols in place for your practice to see excellent results through laser therapy and, as a result, practice growth.