Comparison of substrate utilization patterns in males and eumenorrheic females during submaximal exercise
Year: 1997
Type: dissertation
Abstract: b strate U tilizatio n P atte rn s in M ales an d E u m en o rrh eic Fem ales D u rin g S ubm axim al Exercise (76 pp.) D irector: D r. B rent C. R u ^y P ^/T he p u rp o se of this in v estig atio n w as to exam ine su b strate oxidation an d p la sm a glucose kinetics in m ales a n d reg u larly m e n stru atin g fem ales d u rin g subm axim al exercise.Five recreationally train e d m ales a n d fem ales (VOjpeak = 61.7 ± 2.9 v s 48.6 ± 3.0 m l kg^ m in \ respectively) p erfo rm ed cycle erg o m etry exercise for 25 m in u tes at ~70%VO2 of th eir respective lactate th resh o ld (LT), im m ediately follow ed b y 25 m in u tes of exercise a t ~90%VO2 LT.Fem ale subjects w ere tested d u rin g th e m idfollicular (MF) p h ase (4-6 d ay s after o n set of m enses) a n d d u rin g th e lu teal (L) p h ase (22-27 d ay s after onset of m enses).A ll subjects w ere tested after a n 11 h o u r fast a n d w ith in tw o h o u rs of w aking.C arb o h y d rate an d fat ox id atio n w ere d eterm in ed w ith in d irect calorim etry (respiratory exchange ratio a n d VOj) w h ü e p lasm a glucose p ro d u c tio n (Ra) a n d utilizatio n (Rd) w ere d eterm in ed b y a p rim ed (30 jxm ol kg'^) co n stant in fu sio n (0.42 p m o l kg'^ m in'^) of 6,6-^H-glucose.D u rin g exercise at 70% LT ("40-50% V02peak)/ m ales a n d fem ales, reg ard less of m e n stru al ph ase, oxidized sim ilar p ro p o rtio n s of carb o h y d rate a n d fat.A t rest a n d d u rin g 70% LT, there w ere n o differences b etw e en g en d ers an d m en stru al p h ases in p lasm a glucose Ra a n d Rd.A t 90% LT ("52-62% V02peak)/ m ales a n d MF fem ales oxidized sim ilar p ro p o rtio n s of carb o h y d rates an d fats a n d h a d sim ilar glucose Ra an d Rd (pm ol-kg lean b o d y m ass ' m i n ^).H ow ever, d u rin g the L phase, fem ales te n d e d to oxidize pro p o rtio n ally less carb o h y d rate a n d m ore fat co m p ared to th e m ales (p>0.05) a n d the MF p h ase (p<0.05).In accord w ith th e d ecrease in carb o h y d rate oxidation at 90%LT d u rin g the L phase, p lasm a glucose R d w as lo w er th a n in m ales a n d th e MF p h ase (both p<0.05).W ith th e p re se n t d ata, it can n o t b e d eterm in ed w h e th e r th e differences in su b strate ox id atio n are d u e to increased h p id availability d u rin g th e L p h ase o r a d ecreased glycolytic flux.F u tu re stu d ies in th is area sh o u ld em ploy th e m u s d e b io p sy tech nique to d eterm in e th e pre-exercise m uscle glycogen concentrations.T hese resu lts su g g est th a t conclusions a b o u t g e n d e r differences in su b strate o x id atio n an d p la sm a glucose u tilizatio n d u rin g exercise d e p e n d u p o n th e co m p ariso n exercise inten sity a n d the m e n stru al p h ase of th e fem ales subjects.u
Source: The Mathematics Enthusiast
Author: Theodore W. Zderic
Language: English
Subfield: Complementary and alternative medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W1643263983