During 90 degrees head-up tilt, young men demonstrated larger initial reductions and a prolonged reflex overshoot in finger arterial pressure compared to older men.
Observational (n=33)
valor p: p=<0.05
This study compared the heart rate, finger arterial pressure (AP) and electromyographic (EMG) activity of selected anti-gravity muscles during the initial and prolonged phases of orthostatic stress in healthy young and older men. Beat-by-beat recordings of heart rate, finger systolic pressure, diastolic pressure and mean AP were made during supine rest and 5 min of 90 degrees head-up tilt (HUT) in 18 young (23+/-1 years) and 15 older (73+/-1 years) men. The EMG activity of the soleus, tibialis anterior and vastus medialis muscles was recorded. During the first 30 s following 90 degrees HUT (immediate response), the young men exhibited significant (P0.05) from the values at supine rest for the older men. The mean root mean square EMG activity of the soleus, tibialis anterior and vastus medialis muscles during 90 degrees HUT was not significantly different (P>0.05) from that at supine rest for either group. These results demonstrate that, when compared with healthy older men, young men show larger reductions in finger AP during the initial phase of orthostatic stress. However, during the prolonged phase of orthostatic stress, older men maintain resting finger AP, whereas young men demonstrate a reflex overshoot in finger AP. Finally, differences in lower-limb anti-gravity muscle activation do not account for the contrasting finger AP responses of healthy young and older men.
Gabbett et al. (Tue,) conducted a observational in Healthy (n=33). Young age vs. Older age was evaluated on Change in finger arterial pressure during 90 degrees head-up tilt (p=<0.05). During 90 degrees head-up tilt, young men demonstrated larger initial reductions and a prolonged reflex overshoot in finger arterial pressure compared to older men.