Original articles  CARDIOVASCULAR SYSTEM 

The Journal of Sports Medicine and Physical Fitness 2004 June;44(2):179-85

Copyright © 2004 EDIZIONI MINERVA MEDICA

language: English

Cardiac responses to progressive upright exercise in adult male cyclists

Rowland T. W. ¹, Roti M. W. ²

¹ Department of Pediatrics Baystate Medical Center, Springfield, MA, USA 2 Department of Kinesiology University of Connecticut, Storrs, CT, USA

Aim. Pre­vious inves­ti­ga­tions ­have indi­cated ­that max­imal ­stroke ­volume is the pri­mary ­factor ­which dif­fer­en­tiates phys­io­log­ical ­aerobic ­fìtness (V.O2max) in endu­rance ath­letes ­from non­ath­letes. Under­standing the pat­tern of ­stroke ­volume ­response to pro­gres­sive exer­cise may pro­vide ­insights ­into the mech­a­nisms ­which are respon­sible for ­this dif­fer­ence.
­Methods. Dop­pler ech­o­car­di­og­raphy was ­used to esti­mate ­stroke ­volume ­changes ­with max­imal ­upright ­cycle exer­cise in 8 ­highly ­trained ­adult ­cyclists (­mean age 30.5±1.6 ­years) and 16 age-­matched non­trained ­males. Ven­tric­ular dimen­sions ­were meas­ured ­during exer­cise ­using 2-dimen­sional ech­o­car­di­og­raphy (par­a­stemal ­long ­axis ­view). Find­ings ­were com­pared to a ­group of ­untrained ­adult ­male sub­jects.
­Results. ­Mean max­imal ­oxygen ­uptake was 73.7±7.0 and 47.4±7.5 ml . kg-1.min-1 in the 2 ­groups, respec­tively. ­Stroke ­volume ­rose in ­both the ­cyclists and non­trained sub­jects at the ­onset of exer­cise but ­then pla­teaued ­without ­signifìcant ­change to exhaus­tion. ­Values for ­stroke ­index ­were ­signifìcantly ­greater at ­rest and all ­levels of exer­cise in the ­cyclists (max­imal 85±13 ­versus 61±13 ml.m-2). Two dimen­sional ech­o­car­di­o­grams ­during exer­cise in the ­cyclists ­revealed a ­small ­initial ­rise in ­left ven­tric­ular end-dia­stolic dimen­sion and ­then a ­small ­decline, ­while sys­tolic dimen­sion ­decreased pro­gres­sively, ­resulting in a ­rise in short­ening frac­tion.
Con­clu­sion. ­These ­fìndings are con­sis­tent ­with the con­cept ­that deter­mi­nants of ­stroke ­volume at ­rest are ­most influen­tial in ­defìning dif­fer­ences in max­imal ­stroke ­volume ­between ath­letes and non­ath­letes.