Influence of Fiber Type Composition and Capillary Density on Onset of Blood Lactate Accumulation,
Abstract
Onset of blood lactate accumulation (OBLA) was determined in sixteen healthy and physically active men (23-33 yrs) during cycling using a continuous step-wise increased exercise intensity protocol. OBLA was defined as the exercise intensity corresponding to a lactate concentration of 4 mmol per liter of blood. Oxygen consumption, pulmonary ventilation, respiratory quotient (R), heart rate and lactate concentration were monitored during each exercise intensity. Muscle biopsies were obtained from m. vastus lateralis at rest for determination of fiber type composition and capillary density. Calculated values (mean + or - SD) for exercise intensity, oxygen consumption and ventilation at OBLA were 159 (+ or - 37)W, 2.43(+ or - 0.47) liters per min and 49.8(+ or - 10.5) liters per min or 65(+ or - 10) percent of V sub O sub 2 max OBLA (percent V sub O 2 max) was found to correlate significantly (r=0.75, p less than 0.001) to the relative muscle area occupied by ST (Type I) fibers. Furthermore, 92% of the variance in OBLA could be explained by percent ST area + capillary density. It is suggested that both inherent and adaptative qualities of the exercising muscle are of significance for the onset of blood lactate accumulation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 25, 1981
- Accession Number
- ADA111038
Entities
People
- D. S. Sharp
- P. A. Tesch
- W. L. Daniels
Organizations
- United States Army Research Institute of Environmental Medicine