Lower body positive pressure affects systemic but not cerebral haemodynamics during incremental hyperthermia

2020 ◽  
Author(s):  
Blake G. Perry ◽  
Toby Mündel
Keyword(s):  
Positive Pressure ◽  
Lower Body ◽  
Cerebral Haemodynamics ◽  
Lower Body Positive Pressure ◽  
Body Positive

scholarly journals Effect of Uphill Running on VO2, Heart Rate and Lactate Accumulation on Lower Body Positive Pressure Treadmills

Sports ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 51
Author(s):  
Daniel Fleckenstein ◽  
Olaf Ueberschär ◽  
Jan C. Wüstenfeld ◽  
Peter Rüdrich ◽  
Bernd Wolfarth
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Body Weight Support ◽  
Positive Pressure ◽  
Lower Body ◽  
Lactate Accumulation ◽  
Biomechanical Stress ◽  
Lower Body Positive Pressure ◽  
Weight Support ◽  
Body Positive

Lower body positive pressure treadmills (LBPPTs) as a strategy to reduce musculoskeletal load are becoming more common as part of sports conditioning, although the requisite physiological parameters are unclear. To elucidate their role, ten well-trained runners (30.2 ± 3.4 years; VO2max: 60.3 ± 4.2 mL kg−1 min−1) ran at 70% of their individual velocity at VO2max (vVO2max) on a LBPPT at 80% body weight support (80% BWSet) and 90% body weight support (90% BWSet), at 0%, 2% and 7% incline. Oxygen consumption (VO2), heart rate (HR) and blood lactate accumulation (LA) were monitored. It was found that an increase in incline led to increased VO2 values of 6.8 ± 0.8 mL kg−1 min−1 (0% vs. 7%, p < 0.001) and 5.4 ± 0.8 mL kg−1 min−1 (2% vs. 7%, p < 0.001). Between 80% BWSet and 90% BWSet, there were VO2 differences of 3.3 ± 0.2 mL kg−1 min−1 (p < 0.001). HR increased with incline by 12 ± 2 bpm (0% vs. 7%, p < 0.05) and 10 ± 2 bpm (2% vs. 7%, p < 0.05). From 80% BWSet to 90% BWSet, HR increases of 6 ± 1 bpm (p < 0.001) were observed. Additionally, LA values showed differences of 0.10 ± 0.02 mmol l−1 between 80% BWSet and 90% BWSet. Those results suggest that on a LBPPT, a 2% incline (at 70% vVO2max) is not yet sufficient to produce significant physiological changes in VO2, HR and LA—as opposed to running on conventional treadmills, where significant changes are measured. However, a 7% incline increases VO2 and HR significantly. Bringing together physiological and biomechanical factors from previous studies into this practical context, it appears that a 7% incline (at 80% BWSet) may be used to keep VO2 and HR load unchanged as compared to unsupported running, while biomechanical stress is substantially reduced.

scholarly journals Analysis of 3-D Kinematics Using H-Gait System during Walking on a Lower Body Positive Pressure Treadmill

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2619
Author(s):  
Yoshiaki Kataoka ◽  
Ryo Takeda ◽  
Shigeru Tadano ◽  
Tomoya Ishida ◽  
Yuki Saito ◽  
...  
Keyword(s):  
Motion Analysis ◽  
Wearable Sensors ◽  
Three Dimensional ◽  
Lower Limbs ◽  
Positive Pressure ◽  
Lower Body ◽  
Lower Body Positive Pressure ◽  
Gait Kinematics ◽  
Peak Knee ◽  
Body Positive

Recently, treadmills equipped with a lower-body positive-pressure (LBPP) device have been developed to provide precise body weight support (BWS) during walking. Since lower limbs are covered in a waist-high chamber of an LBPP treadmill, a conventional motion analysis using an optical method is impossible to evaluate gait kinematics on LBPP. We have developed a wearable-sensor-based three-dimensional motion analysis system, H-Gait. The purpose of the present study was to investigate the effects of BWS by a LBPP treadmill on gait kinematics using an H-Gait system. Twenty-five healthy subjects walked at 2.5 km/h on a LBPP treadmill under the following three conditions: (1) 0%BWS, (2) 25%BWS and (3) 50%BWS conditions. Acceleration and angular velocity from seven wearable sensors were used to analyze lower limb kinematics during walking. BWS significantly decreased peak angles of hip adduction, knee adduction and ankle dorsiflexion. In particular, the peak knee adduction angle at the 50%BWS significantly decreased compared to at the 25%BWS (p = 0.012) or 0%BWS (p < 0.001). The present study showed that H-Gait system can detect the changes in gait kinematics in response to BWS by a LBPP treadmill and provided a useful clinical application of the H-Gait system to walking exercises.

Hemodynamic and hormonal effects of prolonged anti-G suit inflation in humans

1992 ◽  
Vol 72 (3) ◽  
pp. 977-984 ◽  
Author(s):  
G. Geelen ◽  
P. Arbeille ◽  
J. L. Saumet ◽  
J. M. Cottet-Emard ◽  
F. Patat ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Plasma Renin Activity ◽  
Plasma Renin ◽  
Left Ventricular ◽  
Renin Activity ◽  
Positive Pressure ◽  
Plasma Norepinephrine ◽  
Lower Body ◽  
Lower Body Positive Pressure ◽  
Body Positive

This study examined the hemodynamic consequences of prolonged lower body positive-pressure application and their relationship to changes in the plasma concentration of the major vasoactive hormones. Six men [36 +/- 2 (SE) yr] underwent 30 min of sitting and then 3 h of 70 degrees head-up tilt. An antigravity suit was applied (60 Torr legs, 30 Torr abdomen) during the last 2 h of tilt. In a similar noninflation experiment, the endocrine responses were measured in the suited subjects tilted for 3 h. Two-dimensional echocardiography was used to calculate ventricular volume and cardiac output. Measurements were made 30 min before and 30 and 90 min after inflation. Immediately after inflation, mean arterial pressure increased by 7 +/- 2 Torr and heart rate decreased by 16 +/- 4 beats/min. Left ventricular end-diastolic volume and systolic volume increased significantly (P less than 0.05) at 30 and 90 min of inflation. Cardiac output increased after 30 min of inflation and returned to the preinflation level at 90 min. Plasma norepinephrine and plasma renin activity were maximally suppressed after 15 and 90 min of inflation, respectively (P less than 0.05). No such hormonal changes occurred during control. Plasma sodium, potassium, and osmolality remained unchanged during both experiments. Thus, prolonged application of lower body positive pressure induces 1) a transient increase in cardiac output and 2) a marked and sustained decrease in plasma norepinephrine and plasma renin activity, which reflect an inflation-induced decrease in sympathetic activity.

scholarly journals Effects Of Posture On Central And Peripheral Vascular Responses To Lower Body Positive Pressure

2005 ◽  
Vol 37 (Supplement) ◽  
pp. S221
Author(s):  
Masashi Ichinose ◽  
Shigeko Hayashida ◽  
Asami Kitano ◽  
Takeshi Nishiyasu
Keyword(s):  
Positive Pressure ◽  
Lower Body ◽  
Peripheral Vascular ◽  
Vascular Responses ◽  
Lower Body Positive Pressure ◽  
Body Positive

Hemodynamic responses to graded lower body positive pressure

1993 ◽  
Vol 265 (1) ◽  
pp. H69-H73 ◽  
Author(s):  
X. Shi ◽  
C. G. Crandall ◽  
P. B. Raven
Keyword(s):  
Forearm Blood Flow ◽  
Venous Pressure ◽  
Positive Pressure ◽  
Intramuscular Pressure ◽  
Lower Body ◽  
Central Venous ◽  
Lower Body Positive Pressure ◽  
Pressure Sensitive ◽  
Body Positive ◽  
Forearm Vascular Resistance

Fourteen healthy young men were exposed to progressive increases in lower body positive pressure (LBPP) from 0 to 40 Torr in the supine position. Central venous pressure (CVP) increased 1.09 mmHg (P < 0.05) at 5 Torr LBPP. Between 20 and 40 Torr LBPP CVP increased 0.85 mmHg, resulting in a total increase of 2.06 mmHg (P < 0.05). During 0–20 Torr LBPP mean arterial pressure (MAP) increased from 86 to 89 mmHg with a slope of 0.15 mmHg/Torr LBPP. Stroke volume and cardiac output were significantly increased at 20 Torr LBPP. Beyond 20 Torr LBPP, MAP increased to 95 mmHg at 40 Torr (P < 0.05) with a slope of 0.32 mmHg/Torr LBPP. Forearm blood flow increased above rest at 40 Torr LBPP (P< 0.05). However, neither peripheral nor forearm vascular resistance decreased significantly from rest. Despite the significant increases in MAP, heart rate was unchanged above 20 Torr LBPP. These data suggest that LBPP produces increases in CVP at 0–20 Torr by translocation of blood volume from the legs to the thorax. At LBPP > 20 Torr, further increases in CVP and MAP were produced by other mechanisms possibly related to an activation of intramuscular pressure-sensitive receptors.

Left ventricular function during arm exercise: influence of leg cycling and lower body positive pressure

2007 ◽  
Vol 102 (3) ◽  
pp. 904-912 ◽  
Author(s):  
Jack M. Goodman ◽  
Michael R. Freeman ◽  
Leonard S. Goodman
Keyword(s):  
Left Ventricular ◽  
Cell Labeling ◽  
Positive Pressure ◽  
Lower Body ◽  
Arm Exercise ◽  
Lower Body Positive Pressure ◽  
End Diastolic Volume ◽  
Body Positive ◽  
Leg Cycling ◽  
Leg Exercise

The purpose of this study was to characterize left ventricular (LV) diastolic filling and systolic performance during graded arm exercise and to examine the effects of lower body positive pressure (LBPP) or concomitant leg exercise as means to enhance LV preload in aerobically trained individuals. Subjects were eight men with a mean age (±SE) of 26.8 ± 1.2 yr. Peak exercise testing was first performed for both legs [maximal oxygen uptake (V̇o2) = 4.21 ± 0.19 l/min] and arms (2.56 ± 0.16 l/min). On a separate occasion, LV filling and ejection parameters were acquired using non-imaging scintography using in vivo red blood cell labeling with technetium 99m first during leg exercise performed in succession for 2 min at increasing grades to peak effort. Graded arm exercise (at 30, 60, 80, and 100% peak V̇o2) was performed during three randomly assigned conditions: control (no intervention), with concurrent leg cycling (at a constant 15% leg maximal V̇o2) or with 60 mmHg of LBPP using an Anti G suit. Peak leg exercise LV ejection fraction was higher than arm exercise (60.9 ± 1.7% vs. 55.9 ± 2.7%; P < 0.05) as was peak LV end-diastolic volume was reported as % of resting value (110.3 ± 4.4% vs. 97 ± 3.7%; P < 0.05) and peak filling rate (end-diastolic volume/s; 6.4 ± 0.28% vs. 5.2 ± 0.25%). Concomitant use of either low-intensity leg exercise or LBPP during arm exercise failed to significantly increase LV filling or ejection parameters. These observations suggest that perturbations in preload fail to overcome the inherent hemodynamic conditions present during arm exercise that attenuate LV performance.

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