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The effects of cold and lower body negative pressure on cardiovascular homeostasis.

Kean DJ, Peacock CA, Sanders GJ, McDaniel J, Colvin LA, Glickman EL - Biomed Res Int (2015)

Bottom Line: The purpose of this study is to determine how cold exposure and lower body negative pressure effected cardiovascular variables.Eleven males (20.3 years ± 2.7) underwent two 20-minute exposures to LBNP.From analysis of this data, cold improved the subject's tolerance to LBNP.

View Article: PubMed Central - PubMed

Affiliation: Exercise and Environmental Physiology Laboratory, Kent State University, Kent, OH 44242, USA ; Department of Kinesiology, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA.

ABSTRACT

Purpose: The purpose of this study is to determine how cold exposure and lower body negative pressure effected cardiovascular variables.

Methods: Eleven males (20.3 years ± 2.7) underwent two 20-minute exposures to LBNP. During the 2 trials, the subjects were exposed to cold air (10°C) (COLD) and to ambient temperature (23°C) (AMB). The trials consisted of a 100-minute pre-LBNP period followed by a 20-minute exposure to LBNP and then a 15-minute recovery period. Cardiovascular variables were recorded every 30 minutes using bioimpedance.

Results: When LBNP was applied during the AMB trials, stroke volume immediately decreased. During the COLD trial, there was a five-minute delay before the decrease in stroke volume. Heart rate increased immediately after LBNP initiation during the AMB trials but there was a delay in the increase during the COLD trials. That same pattern was followed with mean arterial blood pressures. Cerebral oxygenation was significantly lower throughout the COLD trial as compared to the AMB trials. Six subjects reported symptoms of syncope or presyncope during the AMB trials but there were no reports of symptoms during the COLD trials.

Conclusion: From analysis of this data, cold improved the subject's tolerance to LBNP.

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Related in: MedlinePlus

The LBNP box.
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fig8: The LBNP box.

Mentions: Subjects were dressed in athletic shorts only for both trials. Subjects positioned themselves in the LBNP box, which is pictured in Figure 8, up to the level of the anterior superior iliac spine. The subject then lied quietly on a table (Hausmann Industries, Northvale, NJ) for the duration of the trial. LBNP was applied at a level of −40 mmHg for both trials. The LBNP box was placed in the chamber prior to cooling and, for both trials, the top of the box was removed for the initial exposure period. This insured that there was not any increase in core temperature due to being sheltered from the environmental stress. The COLD experimental trial consisted of two components: an initial acute cold exposure (ACE) in an environmentally controlled chamber (Neslab, Napa, CA) followed by the LBNP application period. The acute cold exposure was to last for 100 minutes unless the subject's core temperature dropped 1°C at which time the LBNP application was initiated. LBNP application was terminated after 20 minutes or if the subject began experiencing nausea or lost consciousness. The environmental chamber was controlled within ±3°C of 10°C. There was a 15 min recovery period after the trial. The AMB experimental trial took place in the chamber with the temperature controlled within ±5°C of 23°C. LBNP was applied 100 minutes after initiation of the trial and terminated after 20 minutes. There was a 15-minute-recovery period after the AMB trial.


The effects of cold and lower body negative pressure on cardiovascular homeostasis.

Kean DJ, Peacock CA, Sanders GJ, McDaniel J, Colvin LA, Glickman EL - Biomed Res Int (2015)

The LBNP box.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383401&req=5

fig8: The LBNP box.
Mentions: Subjects were dressed in athletic shorts only for both trials. Subjects positioned themselves in the LBNP box, which is pictured in Figure 8, up to the level of the anterior superior iliac spine. The subject then lied quietly on a table (Hausmann Industries, Northvale, NJ) for the duration of the trial. LBNP was applied at a level of −40 mmHg for both trials. The LBNP box was placed in the chamber prior to cooling and, for both trials, the top of the box was removed for the initial exposure period. This insured that there was not any increase in core temperature due to being sheltered from the environmental stress. The COLD experimental trial consisted of two components: an initial acute cold exposure (ACE) in an environmentally controlled chamber (Neslab, Napa, CA) followed by the LBNP application period. The acute cold exposure was to last for 100 minutes unless the subject's core temperature dropped 1°C at which time the LBNP application was initiated. LBNP application was terminated after 20 minutes or if the subject began experiencing nausea or lost consciousness. The environmental chamber was controlled within ±3°C of 10°C. There was a 15 min recovery period after the trial. The AMB experimental trial took place in the chamber with the temperature controlled within ±5°C of 23°C. LBNP was applied 100 minutes after initiation of the trial and terminated after 20 minutes. There was a 15-minute-recovery period after the AMB trial.

Bottom Line: The purpose of this study is to determine how cold exposure and lower body negative pressure effected cardiovascular variables.Eleven males (20.3 years ± 2.7) underwent two 20-minute exposures to LBNP.From analysis of this data, cold improved the subject's tolerance to LBNP.

View Article: PubMed Central - PubMed

Affiliation: Exercise and Environmental Physiology Laboratory, Kent State University, Kent, OH 44242, USA ; Department of Kinesiology, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA.

ABSTRACT

Purpose: The purpose of this study is to determine how cold exposure and lower body negative pressure effected cardiovascular variables.

Methods: Eleven males (20.3 years ± 2.7) underwent two 20-minute exposures to LBNP. During the 2 trials, the subjects were exposed to cold air (10°C) (COLD) and to ambient temperature (23°C) (AMB). The trials consisted of a 100-minute pre-LBNP period followed by a 20-minute exposure to LBNP and then a 15-minute recovery period. Cardiovascular variables were recorded every 30 minutes using bioimpedance.

Results: When LBNP was applied during the AMB trials, stroke volume immediately decreased. During the COLD trial, there was a five-minute delay before the decrease in stroke volume. Heart rate increased immediately after LBNP initiation during the AMB trials but there was a delay in the increase during the COLD trials. That same pattern was followed with mean arterial blood pressures. Cerebral oxygenation was significantly lower throughout the COLD trial as compared to the AMB trials. Six subjects reported symptoms of syncope or presyncope during the AMB trials but there were no reports of symptoms during the COLD trials.

Conclusion: From analysis of this data, cold improved the subject's tolerance to LBNP.

Show MeSH
Related in: MedlinePlus