title: Response of red cell and plasma volume to prolonged training in humans.
abstract: To clarify the role of progressive heavy training on vascular volumes and hematologic status, seven untrained males [maximal O2 uptake (VO2max) = 45.1 +/- 1.1 (SE) ml.kg-1.min-1] cycled 2 h/day at an estimated 62% of VO2max. Training was conducted five to six times per week for approximately 8 wk. During this time, VO2max increased (P less than 0.05) by 17.2%. Plasma volume (PV) measured by 125I increased (P less than 0.05) from 3,068 +/- 104 ml at 0 wk to 3,490 +/- 126 ml at 4 wk and then plateaued during the remaining four wk (3,362 +/- 113 ml). Red cell (RBC) mass (RCM) measured by 51Cr-labeled RBC did not change during the initial 4 wk of training (2,247 +/- 66 vs. 2,309 +/- 128 ml). As well, no apparent change occurred in RCM during the final 4 wk of training when RCM was estimated using PV and hematocrit (Hct). Collectively, PV plus RCM, expressed as total blood volume (TBV), increased (P less than 0.05) by 10% at 4 wk and then stabilized for the final 4 wk. During the initial phase of training, reductions (P less than 0.05) were also noted in Hct (4.6%), hemoglobin (Hb, 4.0%), and RBC count (6.3%). In contrast, an increase in mean cell volume (MCV, 1.7%) and mean cell Hb (2.3%) was observed (P less than 0.05). From 4 to 8 wk, no further changes (P greater than 0.05) in Hb, RBC, and MCV were found, whereas both mean cell Hb and Hct returned to pretraining levels.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Kinesiology, University of Waterloo, Ontario, Canada.
authors.forename: H J
authors.initials: HJ
authors.lastname: Green
authors.forename: J R
authors.initials: JR
authors.lastname: Sutton
authors.forename: G
authors.initials: G
authors.lastname: Coates
authors.forename: M
authors.initials: M
authors.lastname: Ali
authors.forename: S
authors.initials: S
authors.lastname: Jones
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D004911:Erythrocyte Volume / Q000502:physiology*; D005293:Ferritins / Q000097:blood; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training; D010953:Plasma Volume / Q000502:physiology*; D013997:Time Factors
chemical_list: D005293:Ferritins