A. 1Hr PV Loop Hysteresis. Hysteresis in the Old HVT-HF group was significantly greater than Young HVT-HF and Old HVT-LF groups. Data are presented as mean +/− st.dev N=7 for Young HVT – HF, 7 for Young HVT – LF, 9 for Old HVT – HF, 12 for Old HVT – LF. B. 4Hr PV Loop Hysteresis. Hysteresis of the Old HVT-HF group was greater than that of the Old LVT-HF and Old HVT-LF groups. N=5 for Young LVT – HF, 6 for Young HVT – HF, 3 for Young HVT – LF, 5 for Old LVT – HF, 4 for Old HVT – HF, 5 for Old HVT – LF *p<0.05, **p<0.01.