1 Downhill running and exercise in hot environments increase leukocyte Hsp 72 1 (HSPA1A) and Hsp90α (HSPC1) gene transcripts 2 James A Tuttle 1* , Paul C Castle 1 , Alan J Metcalfe 1,4 , Adrian W. Midgley 3 , Lee Taylor 1# , & 3 Mark P Lewis 2# . 4 5 1 Muscle Cellular and Molecular Physiology (MCMP) Research group, Institute of Sport and 6 Physical Activity Research (ISPAR), Department of Sport Science and Physical Activity, 7 University of Bedfordshire, Bedford, UK. 8 2 National Centre for Sport and Exercise Medicine (NCSEM) England, School of Sport, 9 Exercise and Health Sciences. Loughborough University, Loughborough, UK. 10 3 Department of Sport and Physical Activity, Edgehill University, Ormskirk, UK. 11 4 School of Exercise and Health Sciences, Edith Cowan University, Perth, Australia. 12 # Both of these authors are to be credited as Senior Authors of this work. 13 14 15 Running title: Heat shock protein response to various exercise induced stressors. 16 Keywords: Heat shock response, exercise heat stress, thermotolerance. 17 Word count: 4,890 18 *Correspondence: 19 James Alexander Tuttle 20 Telephone: +44 (0)7516 146008 21 Email: james.tuttle1987@gmail.com 22 Articles in PresS. J Appl Physiol (February 26, 2015). doi:10.1152/japplphysiol.00387.2014 Copyright © 2015 by the American Physiological Society.