indicated an improvement in heart rate and blood pressure responses observed with the application of LBNP after 15 days of bed rest.
Without proper recovery following multiple training sessions or competitions, an athlete increases the risk for poorer performance and overuse injuries [8,10] Mimicking sports massage by stimulating the circulatory system and lymphatic vessels, LBNP is claimed to play a vital role in the recovery of the athlete in order to maximise athletic performance in competitive sport.
Arterial and venous response to tilt with LBNP
test after a 60 day HDT bed rest.
LBNP was applied by a custom made LBNP-chamber previously described  and induced by stepwise suction of air out of the chamber.
The associations between the independent variables LBNP and NPPV and the dependent variables HR, mean arterial pressure (MAP), SV, [DELTA]PP, [DELTA]POP, PVI, and PI were analyzed by linear mixed model regression analyses.
In addition, as discussed above, the LBNP
dataset shows a significant level of variations in the baseline drift.
To answer the question of specificity to hemorrhage, we tested the hypothesis that HPV metrics would be able to differentiate between subjects exposed to LBNP (simulating blood loss) or the same subjects undergoing moderate exercise.
(39) As previously described, we performed a study in which the ability of HPV metrics to differentiate between a state of central hypovolemia simulating blood loss (via LBNP) and physical activity was ascertained (10) While HPV metrics could not reliably distinguish between these physiological conditions (Figure 5), we were able to identify that pulse pressure could differentiate the conditions of physical activity from LBNP (Figure 6).
Specifically, older subjects demonstrated a pronounced flattening of the HR response relative to young subjects during unsupported standing (3), during a lower body negative pressure (LBNP) protocol (19), and during a head-up tilt (HUT) protocol (7).
These results are consistent with findings in which plasma norepinephrine (NE) levels, an indicator of sympathetic efferent activity, were not different between young and older subjects during quiet standing or LBNP (19), or during a head-up tilt protocol (7).
Chronic endurance exercise training:a condition of inadequate blood prssure regulation and reduced tolerance to LBNP. Med Sci Sports Exerc.
Reduction in LBNP tolerance following prlonged endurance exercise training.