Effects of detraining on cardiovascular responses to exercise: role of blood volume

Abstract

In this study we determined whether the decline in exercise stroke volume (SV) observed when endurance-trained men stop training for a few weeks is associated with a reduced blood volume. Additionally, we determined the extent to which cardiovascular function could be restored in detrained individuals by expanding blood volume to a similar level as when trained. Maximal O2 uptake (VO2max) was determined, and cardiac output (CO2 rebreathing) was measured during upright cycling at 50-60% VO2max in eight endurance-trained men before and after 2-4 wk of inactivity. Detraining produced a 9% decline in blood volume (5,177 to 4,692 ml; P less than 0.01) during upright exercise, due primarily to a 12% lowering (P less than 0.01) of plasma volume (PV; Evans blue dye technique). SV was reduced by 12% (P less than 0.05) and VO2max declined 6% (P less than 0.01), whereas heart rate (HR) and total peripheral resistance (TPR) during submaximal exercise were increased 11% (P less than 0.01) and 8% (P less than 0.05), respectively. When blood volume was expanded to a similar absolute level in the trained and detrained state (approximately 5,500 +/- 200 ml) by infusing a 6% dextran solution in saline, the effects of detraining on cardiovascular response were reversed. SV and VO2max were increased (P less than 0.05) by PV expansion in the detrained state to within 2-4% of trained values. Additionally, HR and TPR during submaximal exercise were lowered to near trained values. These findings indicate that the decline in cardiovascular function following a few weeks of detraining is largely due to a reduction in blood volume, which appears to limit ventricular filling during upright exercise.

Maximum and Resting Heart Rate in Treadmill and Deep-Water Running in Male International Volleyball Players

“…Some authors compared aerobic values less than 60% of the highest theoretical value of HR during walking on TM and in DRW and there were no differences in the results (Gleim, & Nicholas, 1989;Whitley, & Schoene, 1987); however, according to our results, as other authors (Butts, Tucker, & Christine, 1991;Eyestone, Fellingham, George, & Fisher, 1993) above of 140 HR the differences among the values of HR are higher in the physical exercise developed on TM and in DRW. The results of this study are in accordance with values given by other authors who are among 10% (Butts, Tucker, & Christine, 1991), 14% (Coyle, Hemmert, & Coogan, 1984) and 16% (Eyestone, Fellingham, George, & Fisher, 1993).…”

“…The maximum heart rate was 7.83% lower in water than for the standard laboratory ergometer test performed on land. Others have proposed values ranging from 10% (Butts et al, 1991), to 14% (Coyle et al, 1984), to 16% (Eyestone et al, 1993;Takeshima et al, 1997) for various populations of international level sportspersons. Although some authors found no differences in aerobic heart rate levels less than 60% of the theoretical maximum heart rate values between walking on land and in water (Gleim & Nicholas, 1989;McMurray, Fieselman, & Avery, 1988;Whitley & Schoene, 1987), this study like some others (Butts et al 1991;Eyestone et al 1993) found that above 140 bpm the differences in heart rate are greater between water-based and land-based exercises.…”

Critical determinants of combined sprint and endurance performance: an integrative analysis from muscle fiber to the human body

“…Firstly, our results show that iSDH activity and residuals were positively associated with capillarization (C/F and CAF) and likely with MCV, facilitating greater interstitial PO 2 , reflected by higher [O 2 HbMb] values. Surprisingly, both iSDH activity and residuals did not relate to RBC, [Hb], and Hct, possibly because those measures neglect differences in blood flow or blood volume (73). Secondly, [Mb] was not associated with iSDH activity or residuals (P = 0.16; P = 0.23, respectively).…”

Body Fluid Changes, Cardiovascular Deconditioning and Metabolic Impairment Are Reversed 24 Hours after a 5-Day Dry Immersion

“…The importance of hypovolemia is shown by inverse relationships between microgravity-induced plasma volume reduction and orthostatic tolerance [29]. Coyle et al [30] showed that the decline in SV and O 2 max and the V  increase in HR and TPR during upright exercise following a few weeks of inactivity (only sedentary daily routines and no training) in men who had been training intensely for several years, was largely due to a decline in blood volume. When blood volume was expanded by dextran solution, the reduction of cardiovascular function after a few weeks of detraining was minimal.…”