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The Journal of Sports Medicine and Physical Fitness 1998 Giugno;38(2):116-23

lingua: Inglese

Effect of lac­tate con­sump­tion on exer­cise per­for­mance

Bryner R. W., Hornsby W. G., Chetlin R., Ullrch I. H., Yeater R. A.

Departments of Exercise Physiology and Medicine, School of Medicine, West Virginia University, Morgantown, WV, USA


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Background. Maintenance of plas­ma glu­cose is impor­tant in endu­rance per­for­mance. Gluconeogenesis or car­bo­hy­drate inges­tion main­tain glu­cose ­after hepat­ic gly­co­gen deple­tion. Lactate may ­also ­serve as a glu­co­ne­o­gen­ic pre­cur­sor as ­well as a ­blood buf­fer.
Methods. To deter­mine if an 8% car­bo­hy­drate (CHO) ­sports ­drink ­with and with­out a 2% lac­tate (L) solu­tion ­increased endu­rance per­for­mance, ­peak pow­er, and ­delayed ­blood aci­do­sis, sev­en ­trained ­cyclists par­tic­i­pat­ed in a dou­ble-­blind ran­dom­ized ­study (6 ­males and 1 ­female) per­formed a bicy­cle ­test to deter­mine max V.O2max HR and the HR asso­ciat­ed ­with the ­first res­pir­a­to­ry ­exchange ­ratio (RER) val­ue great­er ­than 1.0 (tar­get HR). Four bicy­cle ­rides to exhaus­tion, sep­ar­at­ed by one ­week, ­were ­done at a con­stant work­load at a HR 10 ­beats ­below ­each ­subject’s tar­get HR. After a 12-­hour ­fast, sub­jects ­received 100 g CHO 2-3 hrs ­before ­each ­test. Mean exer­cise ­heart ­rate was 86-87% max HR. During the ­final 30 s of ­each ­ride the Wingate pow­er ­test was per­formed. Subjects con­sumed ­either (pla­ce­bo, 2% L, 8% CHO or 8% CHO ­plus 2% L) eve­ry 20 min. Blood sam­ples ­were col­lect­ed ­before, eve­ry 30 min dur­ing and imme­di­ate­ly fol­low­ing the ­test.
Results. No sig­nif­i­cant dif­fer­enc­es ­were ­observed in ­total ­time (pla­ce­bo: 95.3±25.8, 2% lac­tate: 95.7±30.0, 8% CHO: 105.2±37.2, 8% CHO+2% lac­tate: 89.0±28.1 min) or ­peak pow­er (pla­ce­bo: 798.2±241.1, 2% L: 750.1±279.2, 8% CHO: 789.4±353.5, 8% CHO+2% L: 716.3±331.3 Watts) ­among ­drinks. There ­were no dif­fer­enc­es in insu­lin, glu­cose, pH and HCO3- ­after the pow­er ­tests ­among the ­drinks.
Conclusion. Exercise per­for­mance is unaf­fect­ed by ­oral sup­ple­men­ta­tion ­with lac­tate.

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