Phys­i­cal ac­tiv­ity shows ev­i­dence of ben­e­fi­cial ef­fects on im­mune sys­tem

The Weekend Australian - Travel - - Health - EX­ER­CISE CHRIS TZAR

ARE­CENT fea­ture in the pres­ti­gious Jour­nal of Amer­i­can Med­i­cal As­so­ci­a­tion (2008;299(2):160-161) has gained much at­ten­tion within the med­i­cal and health sec­tor. It dis­cussed the ev­i­dence sup­port­ing mod­er­ate ex­er­cise train­ing as a strat­egy to off­set com­pro­mised im­mune func­tion in older adults.

Its sig­nif­i­cance is high­lighted by the fact that in­fec­tions are the lead­ing cause of death for peo­ple aged 65 and older. As the hu­man body ages, the im­mune sys­tem be­comes less ef­fi­cient. Con­se­quently, its abil­ity to fight in­fec­tions and other health is­sues is di­min­ished in com­par­i­son to younger peo­ple.

Ob­ser­va­tional stud­ies sug­gest the in­ten­sity of ex­er­cise in­flu­ences im­mune sys­tem changes. Mod­er­ate ex­er­cise im­proves im­mune func­tion­ing by stim­u­lat­ing pos­i­tive changes in the func­tion and num­ber of var­i­ous im­mune sys­tem cells, such as the nat­u­ral killer cell (NK) — one of the body’s first lines of de­fense against viruses. It also im­proves the killing ca­pac­ity of neu­trophils — re­spon­si­ble for com­bat­ing for­eign mi­cro-or­gan­isms and ini­ti­at­ing the im­mune re­sponse.

In­tense ex­er­cise, on the other hand, ap­pears to sup­press im­mune func­tion. Changes in im­mune mark­ers dur­ing high in­ten­sity or pro­longed ex­er­cise in­clude lower mea­sures of an­ti­bod­ies, de­pressed NK ac­tiv­ity and de­creased neu­trophil ac­tiv­ity.

The ben­e­fits of reg­u­lar phys­i­cal ac­tiv­ity or ex­er­cise for both the pre­ven­tion and man­age­ment of chronic dis­ease and ill-health are well es­tab­lished. Much of the ev­i­dence to date has ob­served changes in the body’s var­i­ous sys­tems — pri­mar­ily meta­bolic, car­dio­vas­cu­lar and mus­cu­loskele­tal. It is only in re­cent years that at­ten­tion has been fo­cus­ing on the im­mune sys­tem. The im­pact of ex­er­cise on the im­mune func­tion has im­por­tant pub­lic health con­se­quences and high­lights the ben­e­fi­cial ef­fects of ex­er­cise on dis­ease pre­ven­tion and man­age­ment.

A re­cent study ob­serv­ing wound heal­ing prop­er­ties in aged mice, pub­lished in the Amer­i­can Jour­nal of Phys­i­ol­ogy — Reg­u­la­tory,In­te­gra­tive­andCom­par­a­tivePhys­i­ol­ogy, re­vealed that ex­er­cise has the abil­ity to re­duce the in­flam­ma­tory re­sponse in wounds (2008;294:R179-R184). The au­thor the­o­rised that ex­er­cise en­cour­ages heal­ing by de­creas­ing lo­cal in­flam­ma­tion.

The re­sults may have sig­nif­i­cant im­pli­ca­tions for the im­mune func­tion of peo­ple with chronic ill­nesses, since in­flam­ma­tion un­der­lies the patho­phys­i­ol­ogy in many dis­eases in­clud­ing type 2 di­a­betes, heart dis­ease, arthri­tis, and Alzheimer’s dis­ease.

In­deed, this may pro­vide fur­ther ev­i­dence that ex­er­cise is a pri­mary ther­apy for peo­ple with di­a­betes, since its two most com­mon sec­ondary com­pli­ca­tions are also strongly linked to in­flam­ma­tory mark­ers. Th­ese in­clude the in­flam­ma­tory C-re­ac­tive pro­tein present in heart dis­ease and the in­flam­ma­tory cy­tokines in foot ul­cers.

Al­though this is a rel­a­tively new area, progress is be­ing made to de­ter­mine the mech­a­nisms that af­fect im­mune func­tion­ing through ex­er­cise, and more im­por­tantly, whether th­ese changes in im­mune func­tion­ing can re­duce the risk of de­vel­op­ing a dis­ease, or at the very least, de­lay its pro­gres­sion.

A fre­quent ques­tion con­cerns ex­er­cise dur­ing ill­ness. Most clin­i­cal au­thor­i­ties in the area of ex­er­cise im­munol­ogy sug­gest the fol­low­ing:

For head colds (runny nose, sore throat with­out fever or gen­eral aches and pains):

Mild to mod­er­ate ex­er­cise (eg walk­ing, short jog­ging pe­riod) does not ap­pear to be harm­ful High-in­ten­sity ex­er­cise should be avoided Higher-in­ten­sity ex­er­cise may be re­sumed a few days af­ter symp­toms have ceased

For chest colds, symp­toms of fever, ex­treme tired­ness, mus­cle aches or swollen lymph glands: Avoid ex­er­cise dur­ing symp­toms Com­mence with light-in­ten­sity ac­tiv­ity a few days af­ter symp­toms have ceased, and al­low two to four weeks be­fore re­sum­ing higher-in­ten­sity ex­er­cise

Dur­ing this pe­riod, mon­i­tor how you feel dur­ing ex­er­cise and dur­ing the re­cov­ery pe­riod, to avoid a re­lapse of symp­toms.

The ex­er­cise dose range for en­hanced im­mune func­tion is con­sis­tent with cur­rent phys­i­cal ac­tiv­ity guide­lines, in­clud­ing both aer­o­bic and strength ex­er­cise. To de­ter­mine the ap­pro­pri­ate ex­er­cises and in­ten­sity for your cir­cum­stances, con­sult your lo­cal ex­er­cise phys­i­ol­o­gist. Chris Tzar is an ex­er­cise phys­i­ol­o­gist and di­rec­tor of the Lifestyle Clinic, Fac­ulty of Medicine, Univer­sity of NSW www.lifestyle­clinic.net.au

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