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Effects of Cyclic Variations in Altitude Conditioning (CVAC) on Wellness and Activity Measures (CVAC)

This study has been completed.
Information provided by (Responsible Party):
Anne Friedlander, Palo Alto Veterans Institute for Research Identifier:
First received: July 28, 2011
Last updated: August 19, 2015
Last verified: August 2015
Cyclic Variation in Altitude Conditioning (CVAC) is a new technique that uses a pod-like device to expose users to controlled fluctuations in air pressure. It is designed to promote quicker altitude acclimatization, thus promoting improvements in exercise capacity at altitude and, possibly, at sea level. However, over the past few years, anecdotal stories from users of the device suggest that the CVAC treatments might be causing changes beyond the expected endurance exercise performance benefits. Therefore, the purpose of the study is to obtain data on some of the previous anecdotal claims regarding the device (e.g. increases in strength, improved glucose tolerance, reduction of neuropathic pain and decreased joint swelling) as well as to obtain broad questionnaire data in order to identify more specific variables to investigate in future studies.

Condition Intervention
Device: CVAC Device (Cyclic Variations in Altitude Conditioning)

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Single Blind (Participant)
Primary Purpose: Health Services Research
Official Title: Effects of Cyclic Variations in Altitude Conditioning (CVAC) on Wellness and Activity Measures

Further study details as provided by Palo Alto Veterans Institute for Research:

Primary Outcome Measures:
  • Plasma Glucose Concentration [ Time Frame: Glucose measurements were made at baseline, 3, 6, & 10 weeks. Blood was collected consistently after a 10-12 h fast the morning after a CVAC session (except for baseline). ]

Enrollment: 28
Study Start Date: January 2007
Study Completion Date: August 2010
Primary Completion Date: August 2009 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Sham Comparator: Control
Sham altitude changes - The CVAC device consists of a small pod-like chamber attached to a computer system that controls a strong pump that can draw air rapidly out of the chamber to increase the simulated altitude. The sham-treated group (SH) was exposed to regular, slowly-fluctuating pressures that reached a maximum altitude of 607 m for all 30 sessions. Sham sessions mimicked the noises and initial pressure-change sensations created in the active sessions, thus giving naıve subjects the impression that they were experiencing altitude treatment. All subjects were blind to their elevation throughout the intervention.
Device: CVAC Device (Cyclic Variations in Altitude Conditioning)
A hypobaric hypoxia chamber
Experimental: Hypoxic intervention
Cyclic Hypobaric Hypoxia (CHH) subjects were given 40 min sessions inside the CVAC device per day (two 20 min sessions sequentially per day), 3 days a week for 10 weeks, for a total of 30 sessions or 20 hours. After familiarization sessions, pre-programmed sessions were administered, progressing from Tier 1 to 5. Subjects rotated through three pre-programmed sessions per Tier and each session varied the pattern and rate of hypoxic fluctuations, so that subjects would experience a constantly changing stimulus at each elevation. Five weeks were allotted to progress from Tier 1 (3048 m) to Tier 4 (5486 m). At Tier 5 (6096 m), there was an additional 5 weeks of exposure.
Device: CVAC Device (Cyclic Variations in Altitude Conditioning)
A hypobaric hypoxia chamber


Ages Eligible for Study:   40 Years to 70 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Healthy middle aged men at risk for metabolic syndrome

Exclusion Criteria:

  • Uncontrolled hypertension,
  • sensitive ears,
  • anything that would preclude person from sustaining rapid pressure changes
  Contacts and Locations
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Please refer to this study by its identifier: NCT01408329

Sponsors and Collaborators
Palo Alto Veterans Institute for Research
Principal Investigator: Anne Friedlander, PhD Veterans Affairs Palo Alto Health Care System
  More Information

Responsible Party: Anne Friedlander, Consulting Professor, Palo Alto Veterans Institute for Research Identifier: NCT01408329     History of Changes
Other Study ID Numbers: FRI0016
Study First Received: July 28, 2011
Results First Received: May 17, 2013
Last Updated: August 19, 2015 processed this record on May 24, 2017