Cardiac Output during Positive and Negative Work

Abstract

Cardiac output was studied in two series of experiments during positive (concentric) and negative (eccentric) bicycle ergometer work. Cardiac output (CO₂-rebreathing and dye dilution methods) was higher during negative work compared to positive work at the same oxygen consumption, provided this was over 1 litre per min. Heart rate was increased to the same extent as cardiac output. Mean arterial blood pressure was also higher, and blood lactate concentration slightly lower for negative work compared to positive work. An increased local temperature and/or a higher muscular tension may be factors which besides oxygen demand influence heart rate and cardiac output during negative work.

Key Words:

• Arterial pressure
• cardiac output
• negative muscle work
• positive muscle work