Cardiac performance in endurance-trained and moderately active young women

Purpose: To compare the cardiac performance of endurance-trained (ET) and m oderately active (MA) young women before exercise and throughout incrementa l work rates to maximum with particular interest in whether their stroke vo lume (SV) levels off at a submaximal work rate or increases to maximum. Met hods: Blood volume (BV), and exercise cardiac performance were examined in seven ET (VO2max = 64.3 +/- 2.0 ml . kg(-1). min(-1)) and seven MA (VO2max = 42.1 +/- 1.0 ml . kg(-1). min(-1)) women, aged 18-30 yr. Cardiac time int ervals were measured at matched heart rates (HR). Results: ET had a signifi cantly larger BV than MA in both mt (ET = 5053 +/- 139, MA = 4327 +/- 202) and mL . kg(-1) (ET = 83.1 +/- 1.4, MA = 72.9 +/- 2.7). The SV of ET was si gnificantly larger than the SV of MA throughout exercise, and the SV of ET increased progressively throughout incremental work rates to maximum. Altho ugh the SV of MA initially leveled off at a submaximal work rate, it underw ent a secondary increase at very heavy work rates. Both diastolic filling r ate (DFR) and left ventricular emptying rate (LVER) were significantly fast er in ET compared with MA at HR of 150 bpm, 170 bpm and HRmax. and in both ET and MA, DFR was significantly faster than LVER at 170 bpm and HRmax. Con clusions: In young women, ET have a larger SV than MA due to an enhanced DF R and LVER, with the primary advantage being DFR (possibly due to their lar ger BV). In addition, the SV of ET increases progressively throughout incre mental work rates to maximum with nt, plateau. whereas the SV of MA levels off through moderate to heavy work rates then undergoes a secondary increas e at very heavy work rates.