In comparison between healthy untrained women and men, women have lower values of what percentages of stroke volume, cardiac output, and VO2 max?

The correct answer reflects the typical physiological differences observed between healthy untrained women and men in terms of stroke volume, cardiac output, and VO2 max. Generally, untrained women have been shown to have about 20% lower values in these measures when compared to their male counterparts.

This difference can largely be attributed to factors such as body composition, hormonal influences, and heart size. Men typically have larger heart sizes, which can lead to greater stroke volume—this is the volume of blood ejected by the heart with each beat. Since cardiac output is a product of stroke volume and heart rate, the differences in stroke volume can lead to lower cardiac output in women, even when heart rates are similar.

VO2 max, which refers to the maximum rate of oxygen consumption measured during incremental exercise, also shows a similar disparity. Lower muscle mass and size in women compared to men contribute to these differences, as VO2 max is influenced by the amount of oxygen the body can utilize during exercise relative to body weight and muscle efficiency.

The 20% difference is a generally accepted figure found in exercise physiology literature, reflecting a significant but not extreme gap. Understanding these physiological differences is crucial for tailoring exercise programs and assessing fitness levels in both sexes.