Exercise training and intensity does not alter vascular volume responses in women

Abstract

Purpose: The effect of endurance training on vascular volumes in females has received little research attention. Further, the effect of exercise training intensity on vascular volumes is unknown. Therefore, we investigated the hypothesis that greater hematologic changes would be induced in women by higher exercise intensity during endurance training.

Methods: There were 26 healthy, sedentary adult females with the following characteristics (mean +/- SD): maximal oxygen consumption (VO2max) = 30.0+/-6.6 ml x kg(-1) x min(-1); age = 32+/-5 yr; body mass index (BMI) = 23.7+/-3.6 kg x m(-2)) who were randomly assigned to control (CON, n = 8); high intensity (HI, 80% of VO2max, n = 10), or low intensity (LO, 40% of VO2max, n = 8) cycle ergometer training groups. Training, conducted 3-5 (3.37+/-0.05) d x wk(-1) for 12 wk, was supervised. Estimated exercise energy expenditure was equated across training groups, progressing from 150-375 kcal per session (mean +/- SE across training weeks = 298+/-0.34 and 297+/-0.37 kcal per session for HI and LO, respectively). Plasma volume (PV, T-1824 dilution); calculated total blood (TBV) and red cell volumes (RCV); calculated total hemoglobin (THb); erythropoietin concentration ([Epo]) and selected hematologic variables were measured at baseline and weeks 2, 4, 8 and 12 of training.

Results: The observed relative (percent) changes in PV, TBV, RCV and THb from pre-training baseline values were not statistically significant. Decreases (p < 0.05) in hematocrit (Hct), hemoglobin ([Hb]) and RBC count were observed in both training groups. Mean corpuscular Hb (MCH) and Hb concentration (MCHC) increased (p < 0.05) during training. [Epo] was decreased at week 2 compared with baseline (p < 0.03), but was similar to baseline at weeks 4, 8 and 12.

Conclusions: Within the limits of this study, endurance training did not increase PV, TBV, RCV and THb in previously sedentary females regardless of the intensity of training.