Consumo de oxigênio e custo energético durante testesSubmáximos em cicloergômetro de braço em indivíduos pósacidenteVascular encefálico

Abstract

After a stroke, high energy demands during physical activities may lead to physicalinactivity and adversely impact functionality. The knowledge about energyexpenditure of various physical activities of stroke individuals is important for thedevelopment of physical activities and exercise programs for this population.However, energy expenditure, in terms of oxygen consumption (VO2) and energycost (EC) of various physical activities has not yet been extensively investigated instroke individuals. Most of the available information is about lower-limb activities,especially walking. Information on VO2 and EC of upper-limb activities is insufficient.Upper-limb activities should also be considered in physical activity and exerciseprograms after a stroke, therefore, it is necessary to investigate energy expenditureof upper-limb activities in this population. In face of the difficulty in standardizingtypical upper-limb activities, that allow for the estimation of energy expenditure ofboth the paretic and the non-paretic upper limbs, unilateral arm crank exercise test,with incremental and submaximal protocol, was proposed to ensure that theparticipants reached similar levels of intensity in both upper limbs, and thus, correctinferences from intra- and inter-individual comparisons could be established. Thus,the objective of the present study was to estimate VO2 and EC of stroke individualsduring unilateral arm crank submaximal exercise tests, performed with both theparetic and non-paretic upper limbs, compared to healthy controls. Twenty-sixparticipants were evaluated: 14 stroke individuals at the chronic phase (54 ± 11years; body mass index: 27.5 ± 3.5; 57% men) and 12 healthy controls (55 ± 9 years;body mass index: 26.5 ± 3.5; 50% men). All participants underwent two unilateral armcrank submaximal exercise tests, each upper limb being evaluated on different days,two to 15 days apart. During the tests, the load was progressively increased by fivewatts every three minutes until the participants reached 85% of their maximum agepredictedheart rate or could no longer maintain a constant rate of 50 rpm. For those,who were beta-blocker users, an effort of six points out of 10 on the modified Borgscale was also considered as a criterion for the end of the test. Peak VO2 (mL.kg-1.min-1) measures were obtained with a gas analysis system during the tests. The EC(mL.kg-1.min-1.watts-1) was calculated from the test peak VO2 divided by the maximumload (watts) reached by the participant. For the VO2, ANOVA did not reveal anysignificant differences between the sides or groups. However, for the EC, significantinteraction between side and group factors was found (F=9.34, p=0.005), indicatingthat the differences between the groups only occurred for the paretic upper limb. TheEC of the paretic upper limb was almost two times higher, when compared with thatof the non-paretic limb of the stroke group (mean difference = 0.46, 95% CI 0.12 to0.81) and the non-dominant upper limb of the control group (mean difference = 0.42,95% CI 0.03 to 0.81). The percentage difference of EC between the upper limbs was41% higher for the stroke group (median = 52%, interquartile range 37% to 154%)than for the control group (median = 11%, interquartile range - 4% to 19%). Theresults suggested that increases in EC of upper-limb physical activities of strokeindividuals only occur on the paretic upper limb. This reinforces the need for thedevelopment of stroke-specific exercise prescription guidelines. Although theunilateral arm crank exercise test showed to be a viable option for the evaluation ofenergy expenditure of both the non-paretic and paretic upper limbs of individuals withstroke, future studies should investigate the relationships between energyexpenditure measures obtained with arm crank exercise tests and those which betterreflect typical activities of the upper limbs of stroke individuals.