Zampagni ML, Corazza I, Molgora AP, Marcacci M.J Electromyogr Kinesiol. 2008 May 1.

ABSTRACT: Risk factors that can determine knee and ankle injuries have been investigated and causes are probably multifactorial. A possible explanation could be related by the temporary inhibition of muscular control following an alteration of proprioceptive regulation due to the ankle imbalance pathology. The purpose of our study was to validate a new experimental set up to quantify two kinesiologic procedures (Shock Absorber Test (SAT) and Kendall and Kendall's Procedure (KKP)) to verify if a subtalus stimulus in an ankle with imbalance can induce a non-appropriate response of controlateral tensor fascia lata muscle (TFL). Fifteen male soccer players with ankle imbalance (AIG) and 14 healthy (CG) were tested after (TEST) before (NO-TEST) a manual percussion in subtalus joint (SAT). A new tailor-made device equipped with a load cell was used to quantify TFL's strength activation in standardized positions. Two trials for each subject were performed, separated by at least one 4-min resting interval. In NO-TEST conditions both AIG and CG showed a progressive adaptation of the subject to the force imposed by operator. No reduction in mean force, mean peak force, and muscle force duration (p>0.5). AIGpresented significant differences (mean difference 0.92+/-0.46s; p=0.000) in muscle force duration in TEST conditions. Our results indicated that "wrong" proprioceptive stimuli coming from the subtalus joint in AIGmight induce inhibition in terms of duration of TFL muscle altering the knee stability. This kinesiological evaluation might be useful to prevent ankle and knee injuries.

Comment: This fascinating study investigates two fundamental procedures developed in AK over 25 years ago. The “shock absorber test” developed in AK is a screening examination for extended foot pronation, subluxations, and other dysfunctions of the foot. When there is foot dysfunction, quite often after striking the foot with many vectors, a previously strong indicator muscle will test weak. This was demonstrated in this controlled clinical trial.