Cardiovascular responses during downhill treadmill walking at self-selected intensity in older adults.

Cardiovascular responses of older adults to downhill (DTW, -10% incline) and level treadmill walking (0%) at self-selected walking speed (SSWS) were examined. Fifteen participants (age 68 ± 4 yr, height 1.69 ± 0.08 m, body mass 74.7 ± 8.1 kg) completed two 15-min walks at their SSWS (4.6 ± 0.6 km/hr). Cardiovascular responses were estimated using an arterial-volume finger clamp and infrared plethysmography. Oxygen consumption was 25% lower during DTW and associated with lower values for stroke volume (9.9 ml/beat), cardiac output (1.0 L/min), arteriovenous oxygen difference (a-v O2 diff, 2.4 ml/L), and systolic blood pressure (10 mmHg), with no differences in heart rate or diastolic and mean arterial blood pressure. Total peripheral resistance (TPR) was higher (2.11 mmHg) during DTW. During downhill walking, an exercise performed with reduced cardiac strain, endothelial changes, and reduced metabolic demand may be responsible for the different responses in TPR and a-v O2 diff. Future work is warranted on whether downhill walking is suitable for higher risk populations.