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

Purpose: The effect of endurance training on vascular volumes in females ha s received little research attention. Further, the effect of exercise train ing intensity on vascular volumes is unknown. Therefore, we investigated th e 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 ((x) o ver bar +/- SD): maximal oxygen consumption ((V)over dot O(2)max) = 30.0 +/ - 6.6 ml.kg(-1).min(-1); age = 32 +/- 5 yr; body mass index (BMI) = 23.7 +/ - 3.6 kg.m(-2)) who were randomly assigned to control (CON, n = 8); high in tensity (HI, 80% of (V)over dot O(2)max, n = 10), or low intensity (LO, 40% of (V)over dot O(2)max, n = 8) cycle ergometer training groups. Training, conducted 3-5 (3.37 +/- 0.05) d.wk(-1) for 12 wk, was supervised. Estimated exercise energy expenditure was equated across training groups, progressin g from 150-375 kcal per session ((x) over bar +/- SE across training weeks = 298 +/- 0.34 and 297 +/- 0.37 kcal per session for HI and LO, respectivel y). Plasma volume (PV, T-1824 dilution); calculated total blood (TBV) and r ed cell volumes (RCV); calculated total hemoglobin (THb); erythropoietin co ncentration ([Epo]) and selected hematologic variables were measured at bas eline 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 (Hc t), 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: Withi n the limits of this study, endurance training did not increase PV, TBV, RC V and THb in previously sedentary females regardless of the intensity of tr aining.