Exercise Induced Plasma Volume Expansion Lowers Cardiovascular Strain

California Baptist University

Status: Completed

Conditions: Cardiac Output; Stroke Volume

Treatments: Procedure: High Intensity Intervals; Procedure: Moderate Exercise

Study type: Interventional

Funder types: Other; Other U.S. Federal agency

Identifiers

NCT05800808

Plasma Volume and Hypoxia

Details and patient eligibility

About

The goal of this observational study was to better understand the impact of increased plasma volume on later exercise in hypoxia. Investigators examined young, healthy, males who regularly participated in aerobic exercise.

Investigators first measured participant's response to exercise in hypoxia (simulated ~7,500 feet above sea level). The investigators then had participants either 1) undergo 1 bout of high intensity interval exercise or 2) undergo 1 bout of moderate, continuous exercise.

48 hours after the exercise, participants were again examined in hypoxia.

Full description

A crossover design was utilized to assess the effects of exercise-induced plasma volume expansion on cycling performance in hypoxia. All participants completed a high intensity (HI) bout and control (CON) intervention in a counterbalanced order. The HI bout consisted of 8x4min cycling bouts at 85% of VO2peak with 4 min rest between intervals. CON consisted of cycling at 50% VO2peak. Two 15 km, self-paced cycling time trials (TT) were performed before and after each training intervention. The first TT occurred 5 days before the training intervention (HI or CON) and the second TT occurred 48 hours post intervention. Interventions were separated by 14 days to ensure sufficient washout of any training effect as data have suggested retention of expanded plasma volume may last for 7-14 days. During washout, participants were instructed to continue their normal exercise routine.

The investigators hypothesized that a single HI session would increase plasma volume and attenuate cardiovascular strain during exercise in hypoxia, as evidenced by reductions in HR and elevations in SV and Q. Furthermore, the investigators hypothesized that these changes would contribute to a reduced time-to-completion in a 15 km, self-paced cycling TT.

Enrollment: 8 patients

Sex: Male

Ages: 18 to 38 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Males age 18-38
• Exercise at least 3 times/week for at least 30 minutes/day for the past 3 months.

Exclusion criteria

• Frequent hot bath or sauna users
• Resided at altitude greater than 2,500 meters for >14 days.
• Cardiovascular or metabolic disease

Trial design

Primary purpose: Prevention

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: None (Open label)

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8 participants in 2 patient groups

High Intensity Exercise

Experimental group

Description:

Vigorous cycling

Treatment:

Procedure: High Intensity Intervals

Continuous Moderate Exercise

Active Comparator group

Description:

Leisurely cycling

Treatment:

Procedure: Moderate Exercise