Even though humans are bipeds and equine are quadrupeds, both mammals have quite comparable musculoskeletal systems that can be analyzed using similar tools and methodologies [1].  Seventy percent of all heat emitted from the body is produced by muscle activity [2].  As a muscle contracts, blood flow increases and stored ATP is broken down into energy [3]. This increase of oxygenation and metabolic activity generates heat which is emitted through the skin in proximity of the activated muscle [4].   Infrared imaging is a precise way to detect anatomical regions and measure the thermal emissions of muscle activity [5]. Equine IR measures infrared data within regions of superficial and intermediate muscles to quantify functional asymmetry related to the effects of compensation patterns - systematic and adaptive overuse of certain muscle groups due to physical predispositions (e.g. tension, weakness, injury, limited flexibility, pain) [6].  Based on biology principles of bilateral symmetry and the use of infrared imaging to quantify asymmetry [7], each muscle region is compared to its symmetrical counterpart to identify and measure thermal asymmetry.  Automated reports are generated to 1) quantify functional asymmetry, 2) analyze the increased demands on muscles, ligaments and joints and 3) calculate the potential effects on posture, balance, and mobility.  

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1.  Crook, T.C., Cruickshank, S.E., McGowan, C.M., Stubbs, N., Wakeling, J.M., Wilson, A.M., Payne, R.C. Comparative Anatomy and Muscle Architecture of Selected Hind Limb Muscles in the Quarter Horse and Arab, J Anat. 2008; Feb; 212(2): 144–52. 

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2.  González-Alonso, J., Quistorff, B., Krustrup, P., Bangsbo, J., Saltin, B. Heat Production in Human Skeletal Muscles at the Onset of Dynamic Exer. Biology Letters.  2001; 8: 864-67.

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3.  Tortora, G.J. and Grabowski S.R. Principles of Anatomy and Physiology.  2000; 9th edn. 1055 pp. New York: John Wiley.

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4.  Pennes HH.  Analysis of Tissue and Arterial Blood Temperatures in the Resting Human Forearm. J. Appl. Physiol.  1948; 1: 93–122. [PubMed] [Google Scholar].

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5.  Al-Nakhli, H.,  Petrofsky, J., Laymon, M., Berk, L. The Use of Thermal Infra-Red Imaging to Detect Delayed Onset Muscle Soreness. J Vis Exp.  2012; 59.  Published online. 

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6.  Lohmann Siegel, K., Kepple, T., Stanhope, S. A Case Study of Gait Compensations for Hip Muscle Weakness in Idiopathic Inflammatory Myopathy. 

Clin Biomech (Bristol, Avon). 2007; Mar; 22(3): 319–26.

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7.  Uematsu S.E., Jankel WR, Kozikowski J., Trattner M. (1988) Quantification of Thermal Asymmetry. Part 1: Normal Values and Reproducibility. J Neurosurg 1988; 69: 552–5.​