Journal of Muscle IQ

Journal of Muscle IQ - Volume 7
May of 2025
 

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RESEARCH ARTICLE: Identifying the Reflexive Origin of Muscle Weakness Through Observation of the Myotatic and Autogenic Inhibition Reflexes

Journal of Muscle IQ - Volume 2 - September 2023

Authors:  Christopher P. Knudsen, DPT and Alyssa Stewart (PT Tech, BYU Student)

Key words: Muscle Weakness, Muscle Inhibition, Afferent Input, Fascia.

ABSTRACT:

Physical therapists treat muscle weakness in patients every day in outpatient clinics.  Most muscle weakness found through manual muscle testing is due to a loss of the Myotatic reflex (or stretch reflex), and/or due to stimulation of the Autogenic Inhibition reflex. This paper will discuss how to identify where the reflexive weakness originates based on testing of the Myotatic reflex.  We summarize the science behind the myotatic reflex, the Autogenic Inhibition reflex, and the role of nociceptors in the Fascia in muscle inhibition and the impact of negative Afferent Input messages received by the spinal cord. The reflexive evaluation method will be explained in great detail using real patient cases in the clinic.  Videos will be included to better explain the actions involved in this process and the responses from the patients. REFLEXIVE TESTING METHOD: How to Identify the Reflexive Origin of Weakness:  Step 1: Perform manual muscle testing to find the weak muscle.  Step 2: Test for loss of Myotatic Reflex of a test limb during contraction of the weak muscle.  Step 3: Identify the reflexive origin of the muscle weakness.  Step 4:  Treat the site.  Step 5: Retest the Myotatic reflex and retest the weak muscle. CONCLUSION: Most muscle weakness found in the outpatient clinic is reflexive weakness and we can use reflex testing to identify the origin of that weakness.  Muscle strength can be restored through treatment at the reflexive origin of that weakness.  Physical Therapists with a basic understanding of manual muscle testing and reflexes will be able to replicate this technique with their patients in an outpatient setting and test the premise of this paper, that most muscle weakness found in the outpatient clinic can be linked to reflexive weakening.  More case study papers should be written to explain the impact of the loss of myotatic reflex on specific injuries found in the outpatient clinic.