Massage Therapy Journal Spring 2025

44 • Massage Therapy Journal

AMTA Continuing Education

Slow-twitch muscles fibers also have numerous mitochondria, which are the structures inside cells that are responsible for energy production. Slow-twitch fibers contract slower compared to fast-twitch fibers. Slow-twitch muscle fibers utilize aerobic metabolism (the use of oxygen) to produce adenosine triphosphate (ATP), or energy. This allows these types of muscles to sustain contractions for long periods of time without fatiguing quickly. They are well-suited for endurance activities, such as long-distance jogging or swimming, which require lower effort but sustained performance. Fast-twitch or type-2 muscle fibers are larger in size and have less myoglobin content with fewer mitochondria in comparison to slow twitch fibers. They contract rapidly, generating a higher force in a shorter amount of time. Fast-twitch muscle fibers generally rely on anaerobic metabolism (without the use of oxygen) to produce ATP or energy, which allows these muscle fibers to generate rapid bursts of power but leads to quicker fatigue since oxygen is not being used. Most muscles in our body contain a mix of both slow-twitch and fast-twitch fibers. The proportion can vary based on genetics, training and the function of specific muscle groups. Athletic performance and training adaptations can be influenced by the types of muscle fibers predominant in a person’s body. Trigger Points: A Common Cause of Pain Myofascial pain syndrome or trigger points are one of the most common causes of musculoskeletal pain. Leon Chaitow defines a myofascial trigger point in his book, Modern Neuromuscular Techniques , as “a localized, palpable area of soft tissue which is painful on pressure and which refers symptoms, usually including pain, to a predictable area some distance from itself.” The term myofascial pain was first described in 1600 by Guillaume de Baillou, and since then many other researchers have also described this denser muscle or fascial tissue that may refer

symptoms to a specific area. Dr. Janet Travell would go on to coin the term trigger points to refer to this tissue, and along with Dr. David Simons, researched and authored two books about trigger points in 1983 and 1992. An active trigger point is defined as a pain or neurologic sensation that the client is familiar with. When the trigger point is palpated, the pain or neurologic sensation increases. In contrast, a latent trigger point can be defined as a pain or neurologic sensation that the client is not familiar with but still increases in neurologic sensation upon applied pressure. Some research has led to the mapping of trigger points, which has shown that they will commonly develop in very specific areas of muscles. Trigger points will also refer pain to a specific area that may be either surrounding the point or distant to the location of the trigger point. It is important to note that trigger points are a pathologic condition, and not everyone’s pain will be caused by trigger points. Furthermore, every trigger point is found in a taut band of muscle, but not every taut band has trigger points in it. Postural and Phasic Muscles Postural muscles act mainly to sustain the posture of the body. Due to the endurance required for this activity, these muscles contain mainly slow-twitch muscle fibers and have a greater capacity for constant work. As such, they may be prone to hypertonicity. Phasic muscles are designed for moving the body through space. Because of this, they contain mostly fast-twitch muscle fibers. Phasic muscles are prone to inhibition and can fatigue more easily than postural muscles. Postural muscles tend to shorten in response to overuse, underuse or trauma, whereas phasic muscles tend to lengthen and weaken in response to these sorts of stimuli. These effects can lead to musculoskeletal imbalance and joint instability when postural and phasic muscles are located on opposing sides of the agonist/antagonist relationship.

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