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Am J C/in Nuir l990 ;5 1 :15 3-7 . P rin ted in U SA . 1990 Am erican So cie ty fo r C lin ica l N u tritio n 15 3

E ffe c t o f in te n s ity o f p h ys ica l a c tiv ity o nb o d y fa tn e s s a n d fa t d is trib u tio n 1 2Ange lo T rem blay , Jean -P ier re D espr# {233 }s, C laude Leblan c, C o ra Lynn C raig ,B lake Ferris , T hom as S tephens , and C laude B oucha rd

ABSTRACT T o eva lua te the effe ct o fin ten s ity o f p hy s ica lactiv ity on body fa tness and fa t d is tr ib u tio n , o bse rva tions of1 366 w om en and 1257 m en w ho p ar tic ipa ted in the 1 981 C an-ada F itness Surv ey w ere an aly zed . S ub jec ts w ere tes ted fo r en -ergy expen d itu re o fleisu re -tim e ac tiv itie s and es tim ated m axi-m al oxygen up take (VO 2m ax), body fatn ess w as m easu red bysub cu tan eous sk in fo ld th ickn esses, and an th rop om e tr ic m ea -su rem en ts w ere m ad e . S ub jec ts o f bo th sexes w ere ca tego rizedin to fou r subg rou ps on the basis o f th eir pa rtic ipa tion in le i-su re- tim e ac tiv itie s o f va rio us in ten sities . In gen era l, su b jec tsprac tic ing v igo rous ac tiv itie s o n a reg u lar basis had low er sub-cu taneous sk in fo ld th ick nesses an d w ais t-to -h ip ra tios (W H Rs)than tho se no t p erfo rm ing th ese ac tiv itie s . T h ese d iffe rencesrem a ined statis tica lly sign ifican t af te r a cov ariance ana lysis w asused to rem ove the e ffec t o f to ta l ene rg y ex pend itu re o f leisu re -tim e ac tiv itie s o n sub cu tan eo us fa t and fa t d is tr ibu tio n . M ore-ov er , the W HR rem a ined sig n if ican tly low er in su b jec ts pe r-fo rm in g h ig h -in tensity exe rcis e a f ter th e e ffec t o f subcu taneo usfa t on fa t d is tr ibu tio n w as ad justed fo r. Am J C lin N utrl9 90 ;5 1 : 153 -7 .KEY W ORDS Fa tn ess , ad ip osity , en ergy exp en d itu re ,phys ical ac tiv ity

In troduc t ionE xerc ise tra in ing is freq uen tly u sed du rin g the cou rse o f a

w eig h t-reduc ing prog ram and its bene ficia l effec ts on fitne ss a rew ell accep ted . The p o ten tia l o f reg u la r exe rc ise to ind ucew eig h t lo s s h as no t been sys tem atica lly dem on stra ted , h ow -ever. Ind eed , som e inv es tig a to rs o bserved th at ex erc ise tra in ingcan in duce a subs tan tia l reduc tion in b ody w eig h t (1 -3 ),w hereas o the rs foun d essen tially no m o rph o log ica l ch an ge inob ese ind iv idu als su b jec ted to th is trea tm en t (4 , 5 ). A c lo se ex -am ina tio n o fthe tra in ing pro to co ls u sed in th ese in vestiga tio nsrevea ls tha t the q uan tity o f exe rc ise pe rfo rm ed w as m uchh igher in stud ies th at show ed a subs tan tia l w e igh t lo ss in corn -pariso n w ith those no t d em onstra ting th is e ffec t. T h is su gges tstha t the im pac t o f train ing on bodyw eig h t and fa t is to som eex ten t depend en t on th e lev el o f en ergy expen d itu re in ducedb y e xe rc is e.

E xercise in ten sity is ano th er d im en sion of exe rc ise p re sc rip -tion th at m ay in fluence ene rgy ba lan ce indep en den tly o f theeffec t o f exerc ise duration . T he comm on be lie f am ong healthp ro fess io na ls is tha t th e op tim al exerc ise p resc rip tion to b e rec -

om m ended in w e igh t-reduc ing program s is a low -in tensity cx -erc ise . T h is ob v ious ly rep resen ts a secu re ap proach bu t a lowin tensity exe rc ise is a lso cons ide red th e m ost ap propria te p re -sc rip tion becau se th e prop ortion o flip id o x id ized is h igh er th antha t o bse rv ed du rin g a v igo rous e ffo r t (6 ). Ifon e co nside rs on lythe ph ysio log ica l adap ta tion s tha t o ccu r du rin g exe rc ise , th ishyp o thesis seem s to be ju stified . H ow ev er , if the po stexe rc iseadap ta tio ns a re also taken in to accou n t, it becom es u nc lea rw he the r a low -in ten sity exe rc ise rea lly rep re sen ts the p rescr ip -tion th at w ill m ax im ize the p ostexe rcise n eg a tive en ergy ba l-ance. In deed , S tev en son e t al (7 ) foun d tha t en fo rced exe rcis eindu ced a sh ort-te rm suppre ssing effec t o n ene rg y in take ,w h ich m igh t be asso cia ted w ith the stre ss gen era ted b y exe rcis e.In a re cen t s tud y L ennon e t a l (8 ) o b ta in ed re su lts sugg e st ingtha t the in crease in restin g m etabo lic ra te (RM R ) indu ced btra in ing m ig h t depend on the in tens ity o f the ex ercise . Th us,the se observa tion s sugg est th at v igo rou s exe rcis e is m ore lik elyto c rea te a neg ativ e ene rgy b alan ce than is low -in ten s ity ex e r-c ise . If th is hyp o thesis is va lid , it co u ld m ean tha t fo r a g iv enlev el o fenergy expend itu re o fac tiv itie s , peop le reg u lar ly partic -ipa ting in v igo ro us ac tiv itie s du ring the ir le isu re tim e a re cha r-acte r ized by red uced ad iposity . To exam in e th is no tio n , w e an -a lyzed da ta o f the 19 81 C anada F itness Surv ey (9 ) in w hichbody fa tness, fa t d is tribu tion , and ene rgy expen d itu re o f lei-su re -tim e ac tiv itie s acco un ting fo r frequency , in tensity , an ddura tion w ere m easured in a la rge co hort o fm en and w om en .

Meth od sSub jec ts

T he su b jec ts w ere w om en (n = 1 366) and m en (n = 1257 )aged 20-49 y w ho pa rtic ipa ted in th e 1 98 1 C an ad a F itness Su r-vey (9 ). T hey w ere m easured fo r energy exp end itu re o f le isu re -tim e ac tiv ities , e s tim ated m axim al o xygen up take (VO 2m ax),and subcu taneous fa t and an th ropom etric charac te ris tics . T he

From the P hy sica l A ctiv ity S c iences L abora to ry . L ava l U nivers ity ,S te -F oy , Q u# {2 33 }b ec,and th e C anad ian F itness an d L ifes ty le R esearch In -stitute, Ot t awa .

2 A ddress rep rin t reques ts to A T rem blay , Phy sica lA ct i vi ty S ci en ce sLaboratory, PEPS , Lavab Universi ty, Sai nte-Foy, Qu#{ 233}bec,CanadaG IK7P4 .

R ece ived D ecem ber 28 ,1988 .A ccep ted fo r pub lication M arch 29 , 1 989 .

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15 4 T R EM B L A Y ET A LT A B L E IE nergy ex p en d itu re o f ac tiv itie s (E EA ), V O2m ax , an d an th ropom e tric charac teris tic s in w om en categ oriz ed by in ten sity o f u sual daily le isu re -ta ct i v i t i e s*

A c tiv ity in ten s ity

A B C D

V ar iab le

(x < 5M E T S )

(n = 848)

(5 x < 7M E T S )

(n = 252)(7 x < 9ME T S )

(n 1 1 2)

(x 9ME T S )

(n = 154 )

S tatistical analy sis

A N O V A A N CO V A t

E EA ( k c a l . k g . y )VO2ma x (mL . k g .m i n )

2 9 7 1 1 9 23 2 .3 5 .0

3 3 3 9 1 333 .6 5 .0

5 0 3 1 6 0 534.74.9

2 5 7 5 4 635.74.2

NS -A #B ,C ,D ;B #D A #B ,C ,D

B o dy w eigh t (k g ) 60 .3 1 0 .7 5 9 .5 9.9 59 .2 9 .0 59 .8 8 .2 N S N SB M I (k g /rn2 ) 23 .0 3 .8 22 .4 3.4 21.9 2.7 22.2 8.2 A # C A # CW ais t-to -h ipratio 0 .760.06 0.7 40.0 5 0.7 50.1 1 0 .730 .04 A #B ,D ;C #D A #B ,D ;C #DC ircum f erences (cm )

W aist 7 3 .0 8. 9 7 1 . I 7.6 70.5 7. 1 69.9 5 .3 A # B, C , D A # B, C , DH ip 96 .2 8 .2 95 .5 6 .6 94 .7 8 . 1 9 5 .5 6 .0 N S N S* S D . N S , p > 0 .05 .t C ov ariance analy sis , con tro llin g for the statistical e f f ec t o f the to tal energ y ex pend itu re o f activ ities .

pro ced ures f o llow ed in th is stud y con f o rm ed toth e H els in k iD ec laration o f 1975 as rev ised in 1983 .Pro toco l

Energy ex pend iture o f le isure-tim e ac tiv itie s w as estim atedb y use o f a ques tion naire sim ilar to the M inneso ta L e isu reT im e A c tiv ity Q uestio nnaire (10 ). A s reported elsew here (9) ,the question naire w as d esigned to co llec t ex ten siv e d etails onle isu re -tim e phy sical ac tiv ity , inc lud in g ty pe , f req uency , d ura-tion , and in ten s ity , f o r period s 1 y . T h e com p le te qu es tion -naire and fu rther de tails o n its adm in is tration and analy sisw ere already pub lish ed (1 1 , 12 ). A descrip tion o f th e 1981 C an-ada Fitness S u rv ey is also presen ted in on e o f these reports (9 ) .

T o tal en ergy ex pend iture o f activ ities w as calcu lated as fo b-lows :To ta l en ergy ex pend iture (k cal . k g . y

= : (N1 X D x mets1)whe re N is th e n um ber o f occas ion s o f ac tiv ity i in th e past 1 2m o, D is th e av erage d uratio n in ho urs o f th at ac tiv ity , andmets is th e en ergy cos t o f th e activ ity ex p re s sed as k ibo cab orie sex pend ed per k ilo gram body w eigh t per hour o fac tiv ity . A m etw as considered as correspond in g to 1 k cal. k g . h of ac tiv ity and th e mets v alu e f or each activ ity w as estab lished by a groupo fex p erts on th e bas is o f the ex ercise and w o rk phy sio log y lite r-ature(l3).

T o de term in e th e e f f ec t o f ex erc ise in tens ity o n ad ip osity ,sub jec ts o f each sexw ere d iv ided in to fo ur su bgroup s on thebasis o f th e mets v alue o f the ir leisu re -tim e ac tiv itie s byus e ofth e fo llow ing criteria: group A , sub jects no t reporting ac tiv itie so f 5 M ET S 6 m o in th e pas t y ear; group B , sub jec ts report-ing ac tiv itie s o f 5 M ET S bu t < 7 M ET S f o r 6 m o in th epast y ear; group C , sub jec ts reporting ac tiv itie s o f 7 M ET Sbu t < 9 M ET S f o r 6 m o in the pas t y ear; and g roup D , sub-jec ts reporting ac tiv itie s o f 9 M ET S fo r 6 m o in the pasty ear. W hen a sub jec t cou ld be classif ied in m ore th an onegroup , he o r sh e w as assigned to the h igh es t re lev an t in ten sitygroup . T he m ean age (S D ) and num ber o f w om en in each

sub grou p w ere as f o llow s : g rou p A , 31 .9 8 .2 y ,n = 84 8 ; g ro upB , 29 .9 8 .1 y , n = 252 ; g roup C , 28 .2 7 .0 y ,n = 112; andgroup D , 28 .5 6 .8 y , n = 154 . T he corresp ond ing v alu es f orm en w ere g roup A , 31 .9 8 .2 y , n = 552 ; g ro up B , 3 0 .2 8 .2y , n = 22 4 ; g ro up C , 29 .5 7 .4 y ,n = 161 ; and g roup D , 29 .77 .7 y ,n= 32 0 .

T he pro to co l used f or m easuring f itness v ariab les, w h ich , lik ethe questionnaire , w ere adm in is tered in the hom e ,w as the C a-nad ian S tandard iz ed Fitness T es t (14). H eart rate response toa standard iz ed , m u ltis tag e, subm ax im al steptest w as measuredf o r th e estim ation o f V O 2m ax . T h is batte ry o f f ie ldtests alsoinc luded the m easu rem en t o f w aist and h ip c ircum feren ces aw e ll as sk in f o ld th ick nesses at the f o llow ing s ites: sup railm ac ,subscapu lar, calf , b icep s, and triceps.St a tistica l pro ce dures

A one-w ay analy sis o f v ariance (A N OV A ) w asused to com -pare v alu es o f th e fo ur in ten sity subg roups o f su b jec ts f or eachdep enden t v ariab le ( 1 5). M oreo v er, w e per fo rmed th e sam ecom pariso n af ter ad justm en t by cov ariance analy sis f or thecon tribu tion o f to tal energy ex pend itu re o f le isu re -tim e ac tiv i-ties o n th e in terg roup d if f erences (15). T he d if f erencesb e twe e nac tiv ity - in ten s ity g rou ps in sk in f o ld th ick nesse s and w ais t-to -hip-c ircum feren ce ratio (W HR ) w ere also stud ied by use o fcov ariance analy sis con tro lling f or the con trib u tion o f to talsub cu tan eous fat (sum o f f iv e sk in f o ld th ick nesses) .

Resu l tsTab les 1 and 2 presen t va lues o fto ta l energy expend iture o f

leisure -tim e phy sical ac tiv itie s , V O 2m ax , and an thropom etriccharac teristic s in w om en and m en , respectiv ely . In general,sub jec ts repo rtin g v ig orous phy sical ac tiv itie s in the ir leisuret im e w ere also charac teriz ed b y h igher lev els o f energy ex pend i-ture o f activ ities ex cep t f or w om en categoriz ed in the h igh estex erc ise -in tensity group , w hose v alu es w ere sim ilar to those othe low est-in ten sity group . A ll these v ariations w ere no t statis ti-cally sig n if ican t, h ow ev er, probab ly because of th e larg e in tra-

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* 1 SD . N S , p > 0 .05 .t C ova rian ce ana lysis , co n tro lling fo r th e sta tis tic a l e ffec t o fth e to ta l en ergy exp en d itu re o factivities.

PHYS ICA L -A CT IV ITY INTENS ITY AND BODY FA T 155TA BLE 2Energy ex pend itu re o fac tiv itie s (EEA ), V O 2m ax , and an th ropom etric charac te ris tic s in m en ca teg orized by in tens ity o fusu al da ily le isu re- tim ea ct i v i t i e s*

A ctiv ity in ten sity

A B C D(x < 5 (5 x < 7 (7 x < 9 (x 9 S ta tis tica l an aly sisMETS ) M ETS ) M ETS ) M ETS )

Variab le (n = 552) (n = 224) (n = 161) (n = 320) A NOVA ANCO VA tE EA ( k c a l . k g . y ) 3 7 6 1 0 6 2 3 7 3 8 0 2 5 2 3 1 3 8 7 4 9 3 1 1 1 6 NS -VO 2m ax(m L .kg .m in ) 42 .27 .1 44 .68 .0 4 4 .27 .5 4 6 .47 .6 A #B ,C ,D ;B ,C #D A #B ,C ,D ;B ,C #DBody w eigh t (kg ) 76 .2 1 1 .5 7 6 .6 1 1 .2 75 .8 10 .8 76 .8 9 .9 N S NSBM I (k g /rn2 ) 24 .7 3 .3 24 .9 3 .3 24 .7 3 .3 2 4 .5 2 .8 N S NSW aist-to -h ip ra tio 0 .88 0 .06 0 .87 0 .06 0 .87 0 .06 0 .86 0.06 A , B , C # D A , B , C # DC ircum ferences (cm )

W ais t 85 .8 9 .0 8 5 .2 9 .0 8 4 .9 8 .8 8 3 .9 8 .0 A # D A # DH ip 97 .7 7 . 1 97 .5 5 .9 97 .0 6 .4 9 7 .8 5 .8 N S NS

* j: SD . N S , p > 0 .05 .t Covarian ce ana lysis , con tro lling fo r the sta tistica l e ffec t o fthe to ta l energy ex pend itu re o f ac tiv itie s .

g ro up va riatio ns in ene rgy ex pend itu re o f ac tiv itie s . A s ex- o fsubcu taneou s fa t than d id sub jec ts n o t p rac tic ing su chpec ted , VO 2m ax w as sign ifican tly h igh er in sub jec ts rep orting itie s , excep t fo r the ca lf sk in fo ld th ickness . F u rthe rm ore,activ ities o f m od era te- to -h igh in ten sity in com parison w ith tab le sh ow s th at the se d ifferences pe rsis ted w hen the cosub jec ts no t p erfo rm ing th ese activ ities . T h is d ifference w as tio n of to tal ene rgy expend itu re o f ac tiv itie s w as rem ova lso revealed by the co va riance an aly sis , w h ich rem ov ed th e cov ariance ana lysis .con trib u tion ofto tal en ergy exp en d itu re o f ac tiv itie s on v aria - T ab le 4 in d icate s tha t m en practic ing v ig o rous ac tiv itie s alsotion s in VO 2m ax . tend ed to have areduced sub cu taneous ad ipo sity . T he in te r-

T ab le s 1 and 2 a lso in d icate th atbody w eigh t w as com para - g rou p d iffe ren ces fo r w om en rev ea led b y th e A NOVA w erees -b le in each ac tiv ity -in ten sity g rou p fo r b o thsexes . O n the other sentially unchanged w hen the contribution of total energy exhand , fem a le and m a le sub jec ts ca tegorized in the h igh est ac tiv - pend itu re o fac tiv itie s to va ria tio ns in ad ipos ity w as rem oity - in tensity g ro up w ere charac te r ized by a reduced W HR (p T he effec t o fexe rcis e in tensity on sk in fo ld th ick nesse s an d< 0 .05 ) , w h ich w as m ain ly exp lain ed b y low erwais t c ircum fer- W HR adju sted fo r the e ffec t o f the sum of sk in fo ld th ick -ences . Th e in terg roup d iffe rences in W HR and w aist c ircum - n es se s is p resen ted in Tab le5. In bo th sexes non e o f th efe ren ce pe rsis ted w hen sta tis tic a l con tro ls w ere p erfo rm ed fo r d iffe ren ces b etw een ac tiv ity - in tensity g ro ups inthe e ffect o fene rg y exp en d itu re o fac tiv itie s (T ab le s 1 a nd 2). th ick nesse s pe rsis ted a fte r the e ffect o f to ta l su bcu taneou s

A s sh ow n in T ab le 3 , w om en pe rfo rm ing m oderate - to -h igh - ipos ity w as con tro lled fo r . O n the o the r hand , af te r the s tatis-in tensity le isu re -tim e activ ities h ad s ign if ican tly low er am oun ts tical co rrec tio n fo r the ro le o f sub cu taneous fat, the

TA BLE 3Subcu tan eous fa t in w om en categor ized b y the in ten sity o fusua l d aily le isu re -tim e ac tiv itie s*

A ctiv ity in tensity

A B C D(x

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15 6 T REM BL A Y ET A LTABLE 4Subcutaneo us fat in m en catego riz ed by the in te nsi ty o fusual d aily le isu re-t im e activ ities*

Variab le

A ctiv ity in te ns ity

StatisticalanalysisA

(x 0 .05 .t C o va riance ana lysis , con tro llin g fo r the sta tis tic al e ffec t o f the to tal ene rg y ex pend itu re o f ac tiv itie s .

rem a ined sign if ican tly low er in su b jec ts w ho pe rfo rm edh igh -in tensity ex erc ise .

DiscussionT he e ffec t o f exe rc ise o nbody w eig h t an d fa t lo ss h as been

in vestiga ted frequen tly and , desp ite the la rg e am oun t o f da taaccum ula ted , unce rta in ty still p ersis ts con ce rn ing w ha t m ayconstitu te the p re sc rip tion tha t w ill m ax im ize calo ric de fic it.Ev id en ce sup ports the concep t tha t m orph o log ica l changes a rem ore pronounced w hen a la rg e am oun t o f ex erc ise is pe r-fo rm ed . O n th e o the r h and , th e av ailab le ex perim enta l d ata d ono t allow u s to add re ss th e questio n ofth e lev el o fexe rc ise in -ten sity th at w ill favor a m ax im al pos tex erc ise nega tive energyba lance (16 ). T hus , the p rim ary g oa l o f the p resen t stu dy w asto loo k at m orpho log ica l ch aracte r is tic s o f peo p le pe rfo rm ingor n o t p erfo rm ing v igo ro us p hys ica l activ ities in the ir le isu retim e on a reg u la r b asis . T he d ata o f the 19 8 1 C an ad a F itnessSurvey w ere pa rticu la r ly app rop ria te fo r investig atin g th iseffect because en ergy ex pend itu re o fac tiv itie s tha t accou n ts fo rfreq uency , in ten sity , and dura tion as w e ll a s sub cu tan ous fa tand an th ro pom etr ic cha rac te ris tics w ere m easu red in a largen a tiona l s am ple .

A s ex pected , pa rtic ipa tion in ac tiv itie s o finc rea sin g leve ls o fin ten sity w as assoc ia ted w ith inc reases in VO 2m ax . T h is is inag reem en t w ith re su lts rep o rted b y Tay lo r et a l (10 ) w ho oh-se rv ed th e sam e ph enom enon w ith th e M inneso ta L e isu reT im e A c tiv ity Q uestion na ire . Th ese ob se rv atio ns su ggest th atthe type o fq uestionn a ire u sed in th e p resen t stud y is va lid fo rd is cr im ina ting be tw een in d iv id ua ls w ith re sp ec t to the in ten -sity o fu sua l le isu re -tim e ac tiv itie s.

T he m ajo r fin d ing ofth is study is th at su bcu taneou s fa t w asgene rally low er in sub jec ts w ho reg u la rly p rac ticed v ig o rousph ysica l ac tiv itie s . M oreov e r, w hen statis tica l co n tro ls w erepe rfo rm ed to rem ove the e ffect o fene rg y ex pend itu re o f ac tiv i-tie s , a sig n ifican t d iffe ren ce pe rs is ted be tw een sub jec ts p rac tic -ing o r no t p rac tic ing v ig orous ac tiv ities on a reg u lar basis . T h isind ica te s tha t the e ffect o fexe rc ise in tensity o nbody fat and its

d is tribu tion w as n o t due to the en ergy cos t o f ac tiv itie s b u t toan e ffect o n o the r com pon en ts o fene rgy ba lan ce . In th issense ,experim en ta l ev idence sugges ts th at th e in ten sity o f ex erc isemigh t in fluen ce ene rgy in take . T hus , acco rd ing to S tev en sone t a l (7 ) , v igo rou s exe rc ise m igh t ex ert a sup press ing e ffect onposte xe rcis e en erg y in take . T his h ypo thesis is supp orted by re-cen t da ta th at in d icate th at the re is a s ign if ican t a ssoc iatio n be -tween th e exe rcis e- ind uced inc rease in ca tech o lam ines an dfood -in take inh ib ition (17).

T he red uc tion inbody fat ob se rv ed in in d iv id ua ls p e rfo rm -ing v ig o rous exe rcis e m ay a lso be exp la ined by an inc rease inpostexercise RM R . Indeed , L ennon e t a l (8 ) recen tly repo rtedda ta su gg estin g tha t the inc rea se in RM R indu ced by train ingm ig h t d ep en d on the leve l o fex e rc ise in tensity .

R esu lts pre sen ted inT ab le 5 in d ica te tha t the e ffec t o f exe r-c ise in tensity on ind iv idu a l sk in fo ld th icknesses w as n o lo ngerob se rv ed a fte r ad ju stm en t fo r th e co ncom ittan t e ffect o f exe r-c ise in tens ity on to ta l subcu taneou s fa t. T h is sugges ts tha t thresponse o f each sk in fo ld w as prop ortiona l to the o ve ra ll re -sp onse o fsubcu taneou s fa t. O n the o the r hand , re su lts in d icate

TABLESE ffec t o fexe rcise in tensity o n w aist- to -h ip ratio and in d iv id ua lsk in fo ld th icknesses co rrec ted fo r the sum ofsk in fo ld th icknesses*

Variab le M en W om enW aist- to -h ip ratio A , B , C # D A , C # DSkin fo ld th ick ness (mm )

Supra iliac N S N SSubscapu lar N S N SCa l f N S N SB iceps N S N STriceps N S N S* N S, p > 0 .05 . In te rg ro up d iffe rences w ere de te rm ined by a covari-

ance ana ly sis co n tro lling fo r the s ta tistica l ef fect o fthe sum of sk in fo ldth icknesses .

t Se e Tab les 1-4 fo r characte ris tic s o fg roup s A , B , C , and D .

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PH Y S ICA L -A CT IV IT Y IN T EN S IT Y A N D B OD Y FA T 15 7that the W H R rem ained s ign if ican tly low er in ind iv idu als w hop rac ticed h igh -in ten sity ex erc ise ev en af te r the e f f ec t o n subcu -taneous f at w as con tro lled f o r. T h is re su lt su ggests that h igh -in ten sity ex erc ise is as soc iated w ith a pre f e ren tial m ob iliz ationof abdom inal f at . T o ou r k now ledge , it isth e f irst tim e that sucha pre f e ren tial reg ional m ob iliz ation o f f at is reported . T hesere su lts are concordan t w ith earlie r reports f rom our labo rato ry(18 , 19 ) ind icating a tren d f o r a greater red uc tion o f abd om inalf at du ring ex erc ise -in du ced fat lo ss. T h e p resen t report f urtheraddresse s th is is sue b y con tro lling f o r the red uc tion in to tal f at,w hich is im portan t co nsidering the w ell-e stab lished po sitiv e re-latio nsh ip b etw een ob es ity and th e propo rtio n o f abdom inalf at (2 0-2 3).

W e ack now ledge that ou r stud y repo rts cro ss-sectio nal o h-serv atio ns th at w arran t f urther inv estig atio n in a long itud inalex erc ise -train ing s tudy . C on sidering the im po rtan ce o f abdom -inal f at as a corre late o f the m etabo lic com p licatio ns o f ob esity(20 -2 3 ), th e e f f ec t o f ex e rc ise in ten sity on the pro portion o fabdom inal fat cou ld hav e bene f ic ial ef f ec ts on the health p ro f ileo f seden tary ind iv iduals. S u ch an issue also dese rv e s f u rthe rinvest iga t ions.

R esu lts presen ted in T ables 3 and 4 show ed that statis ticallysign if ican t e f f ec ts o f ex erc ise in ten sity on subcu tan eous fat w ereobserv ed m o re sy s tem atically in w om en th an in m en . T h is islik ely ex p lained by th e f act that th e c rite rio n o f ex e rc ise in ten -sity th at cou ld b e used f rom the questio nnaire represen ted agreater relativ e stress f or w om en than f or m en . T h ere fo re , thesedata shou ld no t be used to specu late abou t the ex istence o f sexd if f e rences in th e ab ility to adap t to ex ercise train ing .

In sum m ary , the resu lts o f th is stu dy show that ind iv idualsp erf orm ing v igo rous ac tiv itie s are charac teriz ed by reducedle v e ls o f subcu taneous ad ipos ity and W H R . T h is phenom en onis also observ ed w hen the s tatis tical e f f e c t o f to tal energy ex pen -d itu re o f le isu re- tim e ac tiv itie s on su bcu taneous f at is rem o v ed .T he ef f ec t o f ex erc ise in ten sity on f at d istrib u tion also seem s tobe independ en t o f v ariations in to tal sub cu tan eous f at. #{ 163 } 3

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