Original articles  EXERCISE PHYSIOLOGY AND BIOMECHANICS 

The Journal of Sports Medicine and Physical Fitness 2002 December;42(3):403-8

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Substrate utilization during arm and leg exercise relative to the ventilatory threshold in men

Yasuda N., Ruby B. C., Gaskill S. E.

Human Performance Laboratory The University of Montana, Missoula, MT, USA

Back­ground. The pur­pose of ­this ­study was to deter­mine vari­a­tions in sub­strate util­iza­tion in men ­during arm and leg exer­cise at 70 and 90% of ­mode spe­cific ven­til­a­tory ­threshold (Tvent).
­Methods. Ten ­males ­served as sub­jects. ­Limb ­total and ­muscle vol­umes ­were esti­mated in the ­right arm and leg ­with anthro­pom­etry. Ven­til­a­tory equiv­alence, ­excess CO2, and mod­i­fied V-­slope ­methods ­were ­used to deter­mine ­Tvent. Sub­jects per­formed 15 min of exer­cise at 70 and 90%­Tvent arm ­cranking (AC) exer­cise, and 70 and 90%­Tvent leg ­cycling (LC) exer­cise.
­Results. VO2, VE, and HR ­were ­higher ­during LC exer­cise at ­both inten­sities. How­ever, arm and leg RPE ­were not dif­ferent at 70 and 90%­Tvent. ­There ­were no sig­nif­i­cant dif­fer­ences ­between ­modes at 70%­Tvent in rel­a­tive car­bo­hy­drate use (54.5±9.5 and 57.8±8.2% for AC and LC, respec­tively) and rel­a­tive fat oxi­da­tion (45.5±9.5 and 42.2±8.2% for AC and LC, respec­tively). How­ever, at 90%­Tvent, rel­a­tive car­bo­hy­drate oxi­da­tion was sig­nif­i­cantly ­higher ­during AC ­versus LC exer­cise (75.4±10.6 ­versus 68.6±9.0%, p<0.05). ­Energy expen­di­ture (­total kJ·min-1) was sig­nif­i­cantly ­lower ­during AC exer­cise (14.5±2.9 and 18.4±3.4 for the 70 and 90%­Tvent, respec­tively) ­versus LC exer­cise (27.1±3.3 and 34.8±4.1 for the 70 and 90%­Tvent, respec­tively; p<0.05).
Con­clu­sions. ­These ­results indi­cate ­that sub­strate use ­during AC exer­cise is sim­ilar to LC exer­cise at 70%­Tvent. How­ever, as the exer­cise inten­sity ­increases, the ­smaller arm mus­cu­la­ture ­becomes ­more depen­dent on car­bo­hy­drate util­iza­tion com­pared to the ­legs.