Reduced cardiovascular and metabolic responses during eccentric stepping exercise: A pilot study.

Abstract

This study compared cardiovascular and metabolic responses during concentric and eccentric stepping. Eight participants (5 m, 3f; 22 ± 2 years) performed maximal concentric and eccentric ramp incremental tests on a modified stepping ergometer. Subsequently, three randomized 15-min constant-power tests were performed (1) concentric stepping at 90% of the concentric lactate threshold (LT), (2) eccentric stepping at the same power, and (3) eccentric stepping at the same oxygen uptake (V̇O₂). At equivalent power (36 ± 6 W, p = 0.62), eccentric stepping resulted in 46 ± 8% lower V̇O₂, 16 ± 6% lower heart rate (HR), and 11 ± 5% lower mean arterial blood pressure compared to concentric (p < 0.01). Matching V̇O₂ required 65 ± 19% more power during eccentric stepping (p < 0.01). During this test, eccentric V̇O₂ and HR continued to increase, resulting in a 22 ± 29% higher V̇O₂ and 19 ± 16% higher HR in the final minute (p < 0.001). Reduced cardiorespiratory demand during eccentric stepping at the same power as concentric demonstrates a higher eccentric power is required to produce the same V̇O₂. However, despite being below the concentric LT, eccentric V̇O₂ and HR continued to increase past the predicted steady state, indicating a higher exercise intensity.