Inflammation

Optimizing Injury Recovery

Bodily or joint injury has been associated with pain, structural impairments, functional limitations, and disability [1]. Though long, painful, and arduous, restoration of neuromuscular function is of vital importance in the injury recovery process [2]. For those suffering from pain from a potential back or neck injury, only strengthening exercises seemed to be an effective treatment [3]. However, even strengthening exercises may not fully lead to injury recovery in a timely manner. Only 72% of patients who suffered from a shoulder injury (rotator cuff tear) recovered adequate strength, endurance, range of motion, and joint stability after 6 months of rehabilitation [4]. 

It has been reported by the National Center for Health Statistics (which is a department within the Centers for Disease Control and Prevention) that approximately 31 million people get injured in the United States each year. Individuals may be suffering from a neck injury, shoulder injury, knee injury, and/or many other injuries that require medical treatment/hospitalization. These severe injuries consequently result in extensive injury recovery times. 

Aside from solely aiming to improve functional limitations during the injury recovery process, specialists (physical therapists, occupational therapists, etc.) must also address inflammation. Clinical hallmark signs of inflammation include warmth, swelling, and pain. Inflammation is a major cause of functional loss and pain at the onset of injury and throughout the entire recovery process. Inflammation is important to the recovery process, though, as demonstrated above, standard injury recovery treatment may not be sufficient enough to efficiently enhance injury recovery times [4]. The use of state of the art, scientifically designed, treatment modalities like PowerDot may be pivotal to enhancing injury recovery times and reducing inflammation. 

PowerDot combines the power of two widely used treatment modalities into one advanced piece of wireless technology: Transcutaneous Electrical Nerve Stimulation (TENS) and Neuromuscular Electrical Stimulation (NMES). TENS and NMES aid in the injury recovery process by reducing both pain and inflammation, expediting the healing and recovery processes [5,6]. With PowerDot, everyone now has access to an affordable and FDA approved device to optimize injury recovery.

Physiological Mechanisms Behind Injury and Inflammation

When injury occurs, consequently, an inflammatory process commences. As previously mentioned, some of the clinical hallmark signs we see with injury and inflammation are warmth, edema (swelling), and pain. The warmth is caused by vasodilation of the blood vessels as blood rushes to the site of injury. The swelling is resultant of vascular permeability as fluids leak out of the blood vessels. Lastly, pain is caused by the release of various cellular products that stimulate nociceptors (pain receptors) causing pain signals to be sent to the central nervous system (CNS) to perceive pain [7].

Now, to be clear, an injury may be anything from a torn anterior cruciate ligament (ACL) to a knee scrape to microscopic musculoskeletal tears that result in delayed onset muscle soreness (DOMS). Each of which result in a similar inflammatory response and those clinical hallmark signs.  

There are two different types of inflammation: acute and chronic. Acute inflammation may last a couple of days or a couple of weeks whereas chronic inflammation is persistent inflammation beyond 2-weeks. For instance, during the injury recovery process, patients may experience several bouts of acute inflammation. Acute inflammation is evident immediately after surgery as there is a lot of swelling post-operatively. During physical rehabilitation, a new exercise may be implemented resulting in another acute bout of inflammation. All this to note, acute inflammation soon resides. Now, for our purposes, we will focus on the acute inflammatory processes as chronic inflammation is more relevant to various diseases like: obesity, type II diabetes, heart disease, arthritis, etc. 

Let’s walk through this step by step and discuss the physiology behind acute inflammation and injury recovery. Now, prior to the inflammatory process there is first some injury to vascularized tissue (muscle, skin, ligaments, etc.). In essence, cells are damaged and disrupted. A good example to think about is the inflammatory and healing process of a scraped knee. Now, when someone scrapes their knee a scab is made, the healing skin is a little red and warm, and it can be painful to the touch. So, just like when our body makes a scab from scraping our knee (skin cells on outside of our body are damaged), the same thing happens when the cells on the inside of our body are damaged. Whether the injury is visible or on the inside of our body, there are a series of physiological responses that result in the clinical hallmark signs of inflammation previously mentioned: warmth, swelling, and pain. 

First, there is an activation of what are called “plasma systems”. These plasma systems consist of the coagulation, kinin, and complement systems. The coagulation system does what it sounds like, sends blood platelets to coagulate and gather together at the injured site to heal the area. The kinin system is important because it releases bradykinin which causes vasodilation of blood vessels to bring blood to the injured site. Though, bradykinin, along with prostaglandin, stimulates nociceptors resulting in pain. Lastly, the complement system is activated in order to help clear debris and destroy any foreign material. In regards to injured skeletal muscle, the complement system responds immediately upon injury signaling the infiltration of neutrophils and macrophages (inflammatory cells that help clear debris) to the injured site [8,9].

Alongside the complement system, it is evident that Mast Cells (which are cells located within connective tissue, like muscle, which respond to injury) become degranulated [10]. Degranulation is a process by which various cellular products are released from the cell. Mast cell degranulation is a rapid response to muscle damage and leads to the release of proinflammatory cytokines (ie.TNF-α, IL-1, histamine) [11,12]. These proinflammatory cytokines create what is called a “chemotactic gradient” that recruits and attracts more mast cells, neutrophils and other immune cells to the injured site [11,12]. Mast cells and neutrophils help to clear damaged muscle fibers from the injured area while also recruiting more macrophages to also help clear up necrotic (dead) cells (may be muscle cells) and cellular debris [13,14,15,16]. 

Lastly, there is the release of more cellular products. Yes… more… The human body takes injury recovery very seriously. These cellular products are more cytokines but released from macrophages and T-cells (T-Cells are part of our immune system response). We’ve discussed macrophages above, but to provide further background, macrophages are derived from blood monocytes and recruited to the muscle injury sites by neutrophils shortly after injury [17,18,19,20].

To summarize, and an important note to make, these acute inflammatory processes are a consequence of some type of cell injury resulting in a physiological response which displays the visible clinical hallmark signs of inflammation [13]. Inflammation is part of the healing process and is ok, however, as we will see later, it is possible to aid in expediting the inflammatory and healing process.

Practical Example of Inflammation and Delayed Onset Muscle Soreness (DOMS)

To further put this inflammatory and injury recovery process into perspective, let’s examine DOMS. DOMS is the soreness and pain that is felt 24-72 hours after strenuous unaccustomed exercise or physical activity (ie. eccentric training) and is the result of microscopic muscular injury (damaged muscle cells). Where there is cellular damage there is an inflammatory process. 

Skeletal muscle anatomy is composed of several layers leading all the way down to the muscle cell (aka muscle fiber). Within the muscle fibers are numerous myofibrils which contain our contractile protein elements (actin and myosin) which make-up the sarcomere. The sarcomere is the basic contractile element of skeletal muscle. Actin and myosin connect with one another, ultimately resulting in the contraction of our muscles. Without actin and myosin, our muscles would not contract or produce force.

In regards to DOMS, the muscle damage that does occur is evident at the level of the sarcomere. Meaning, these are microscopic microtears. The damage that occurs is displayed at a location on the sarcomere known as the Z-Disk or Z-Line. The Z-Disk is where actin is anchored or attached to. If actin is not sufficiently anchored, then the interaction between actin and myosin is imparied and force production is decreased [21]. Understanding now where the structural damage is occurring, let’s tie together the inflammatory process and break it down step by step. 

Step 1: A new and/or challenging activity or exercise causes excessive muscular strain resulting in damage to the muscle cell membrane.

Step 2: Damage to the muscle cell membrane disturbs calcium homeostasis resulting in higher than normal calcium levels that go on to activate enzymes that degrade the Z-Disks.

Step 3: In a short period of time, neutrophils and other inflammatory markers begin to accumulate in the injured area.

Step 4: The products of macrophage activity and intracellular contents (histamine and kinins) accumulate outside of the cell and stimulate free nerve endings in the muscle causing pain.

Step 5: Fluid and electrolytes shift into the area (swelling) and also activate pain receptors. 

Though DOMS is a minor cellular injury compared to other more traumatic and debilitating injuries, it is evident that there is a similar inflammatory process. In summary, the inflammation associated with muscle damage triggers pain receptors that results in the painful muscle soreness feeling [22,23]. Ultimately, PowerDot may be used to reduce inflammation as a result of any type of injury, specifically injury associated with DOMS, to help you stay active and feeling your best everyday!

PowerDot and Inflammation

Precious time is wasted every day on various recovery modalities and time-consuming exercises to reduce inflammation and recover from injury or soreness. PowerDot combines the technology of both TENS and NMES into a wireless affordable and FDA approved device to combat pain from inflammation and expedite the injury recovery process. 

The NMES technology creates an electro-induced hyperfusion that may help to wash out and clear away cellular debris accumulated during the inflammatory response thereby decreasing pain [24]. This is evident as previous findings indicate lower inflammatory levels and muscle soreness values 24-hours post-training in those that utilized NMES compared to those that did not [6]. Another group of researchers also found electrostimulation to be more beneficial than other traditional methods for reducing muscle pain [25]. Though, let’s not forget the importance of TENS. The utilization of TENS has also displayed a significant impact in decreasing pain associated with DOMS and reducing markers of inflammation [26,27].

The practical application and benefits of NMES and TENS technology from PowerDot is unmistakable in the DOMS scenario. However, what about major injury recovery like from a rotator cuff or ACL tear? 

As previously mentioned, injury has been associated with pain, functional limitations, and disability [1]. A variety of interventions are used to help people recover, though ultimately, strengthening exercises are the most widely accepted [2]. However, with that said, previous findings indicate that it may take over 6-months to fully regain neuromuscular function [4]. 

NMES and TENS are both treatment modalities used within various rehab clinics and human performance centers to efficiently optimize injury recovery by decreasing pain and enhancing neuromuscular adaptations to exercise. For instance, in ACL reconstruction patients, those who were treated with NMES demonstrated greater quadriceps strength and returned to agility training sooner [5]. Utilization of NMES prior to surgery (knee replacement surgery), in those with osteoarthritis (severely damaged/injured knee joint), demonstrated faster recovery of quadriceps muscle strength and a more expedited return to activity [28]. NMES has also been shown to reduce both structural and functional losses of the quadriceps muscles in those with osteoarthritis [29]. Lastly, by stimulating one leg with NMES and using the other leg as a control, researchers revealed a 24% increase in strength in the NMES leg and only a 10% increase in the control leg [30].

Backed by science, PowerDot harnesses the technological power to optimize injury recovery. Whether recovering from surgery or experiencing the painful effects of DOMS, grab yourself the new PowerDot 2.0, risk free, and do not let injuries slow you down.

References

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