Original articles  Immunology 

The Journal of Sports Medicine and Physical Fitness 2002 September;42(3):368-78

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Exercise under hot conditions: a major threat to the immune response?

Shephard R. J.

From the Faculty of Physical Education and Health and Department of Public Health Sciences University of Toronto, Toronto, Canada Defence and Civil Institute of Environmental Medicine Toronto, Canada

It ­seems like­ly ­that the dis­tur­banc­es of ­immune ­response ­induced by pro­longed com­pet­i­tive exer­cise are exac­er­bat­ed if ath­letes ­also ­face the ­stress of hot envi­ron­men­tal con­di­tions. We ­have inves­ti­gat­ed ­this ques­tion by manip­u­lat­ing the exer­cise-­induced increas­es of ­body tem­per­a­ture in a cli­mat­ic cham­ber and by sub­mer­sion of exer­cis­ers in a ­large ­water-­bath. Hot con­di­tions ­increase the ­stress of a giv­en ­bout of exer­cise, as ­assessed by per­son­al per­cep­tions, objec­tive (­heart ­rate var­i­abil­ity) meas­ures of auto­nom­ic ­nerve bal­ance, and the secre­tion of “­stress” hor­mones, ­with a par­allel ­increase in ­effects ­upon crit­i­cal lym­pho­cyte sub­sets. Chang­es in the ­immune ­response ­show sub­stan­tial cor­re­la­tions ­with plas­ma con­cen­tra­tions not ­only of epi­neph­rine (­which mod­ulates the adhe­sive­ness of periph­er­al­ly seques­tered lym­pho­cytes), but ­also ­with nor­epi­neph­rine. The lat­ter hor­mone may mobi­lize leu­ko­cytes ­from the ­spleen and ­lymph ­glands, or it may act by increas­ing car­diac out­put and ­thus intra­vas­cu­lar ­shear forc­es. Giv­en the cumu­la­tive ­impact of var­i­ous envi­ron­men­tal stres­sors ­upon the ­immune ­system, eve­ry ­effort ­should be ­made to min­i­mize the ­athlete’s expo­sure to stress­es oth­er ­than the exer­cise to be per­formed. In ­some cir­cum­stanc­es, the use of med­i­ca­tions to ­reduce the over­all ­stress ­response may ­also be war­rant­ed.