Skeletal muscle metabolism after stroke: A comparative study using treadmill and overground walking test
Ana Paula C. Loureiro, Birgitta Langhammer, Terje Gjøvaag, Hege Ihle-Hansen, Luiz César Guarita-Souza
Department of Physical Therapy, Pontifícia Universidade Católica do Paraná - School of Life Sciences,
80215-901 Curitiba, Brasil. E-mail: firstname.lastname@example.org
Objective: The primary aim of this study was to investigate muscle metabolism in stroke survivors
through measurements of the respiratory exchange ratio and rates of fat and carbohydrate oxidation in relation to total energy expenditure at preferred walking speed during treadmill and overground walking. The secondary objective was to investigate whether the energy source used during walking influences the daily physical activity pattern and fatigue of post-stroke individuals.
Methods: The sample comprised 28 stroke participants and 10 non-disabled, healthy controls. Measurements of oxygen consumption and carbon dioxide production were recorded. Participants wore a uniaxial accelerometer (activPAL™) over 4 days as an estimate of daily physical activity. Measurements of Human Activity Profile and Neurological Fatigue Index for stroke were documented.
Results: Carbohydrate oxidation accounted for the majority of fuel oxidation at preferred walking speed in the stroke group (55.86% vs 47.29% during tread-mill walking and 66.13% vs 50.15% during overground walking). Stroke patients who had higher levels of carbohydrate oxidation reached a lower score in the Human Activity Profile survey, had fewer steps screened by activPAL data (4,422 vs 6,692 steps/day) and higher fatigue index.
Conclusion: Carbohydrate oxidation accounted for the majority of fuel oxidation at the preferred walking speed in post-stroke individuals. The increased carbohydrate utilization recorded at preferred walking speed may have influenced the physical activity profile.
This study evaluated the type of energy substrate used during walking test in 28 people who had suffered stroke. The skeletal muscle uses fat and carbohydrate (CHO) as fuel source during contractile activity. CHO stores are limited in muscles, thus a high rate of CHO oxidation during ordinary walking can affect endurance capacity and perceived fatigue. The fact that CHO was the primary fuel selected for the stroke participants during preferred walking speed, we believe may have influenced the levels of physical activity in persons with stroke. An improved understanding of substrate oxidation during walking in post stroke individuals is important, in order to adapt exercise to the optimal therapeutic modality.
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