Identification of Critical Thermal Environments for Aged Adults

• Sponsor: Penn State University (Other)
• Overall Status: Recruiting
• CT.gov ID: NCT04284397
• Collaborator: (none)
• Enrollment: 190
• Location: 1
• Arms: 2
• Anticipated Duration (Months): 50
• Patients Per Site Per Month: 3.8

Study Details

Study Description

Brief Summary

This study evaluates critical environmental limits (temperature and humidity) above which older adults are unable to effectively thermoregulate. Participants will exercise in a series of different environmental conditions to identify combinations of temperature and humidity above which age-related physiological changes cause uncompensable heat stress, resulting in increased risk of heat illness.

Condition or Disease	Intervention/Treatment	Phase
Aging	Drug: Low dose ASA; Other: Control	Early Phase 1

Detailed Description

The earth's climate is warming well above historical averages, and there is an increased frequency, duration, and severity of heat waves. At the same time, the world's population is rapidly aging. Aging is associated with reductions in thermoregulatory capacity due to reductions in sweating and skin blood flow. For this reason, people ≥65 years exhibit exponentially larger increases in morbidity and mortality during heat waves than younger individuals, with the large majority of excess deaths during heat waves occurring in the elderly.

Compounding the physiological effects of primary aging, co-morbidities and common classes of drugs taken by older adults can further compromise their thermoregulatory function. One such class of medications is cyclooxygenase inhibitors, including aspirin (ASA) and other platelet inhibitors. Provocative data published by our lab indicate that platelet inhibitors including ASA increase the rate of heat storage during passive heat stress by ~25%. Following current clinical guidelines, nearly 40% of US adults over the age of 50 engage in an aspirin therapy regiment for the primary or secondary prevention of cardiovascular disease.

Although there is compelling evidence that aging is associated with decreased heat dissipation and elevated risk of heat illness in hot ambient conditions, the significant question remains: In what specific environments does this age disparity begin to occur? The goal of the current study is to identify and model ambient conditions that are unsafe for older adults. A second aim of the study is to determine the effects of the commonly used platelet inhibitor, acetylsalicylic acid (ASA), on age-specific critical environmental limits.

Study Design

• Study Type: Interventional
• Anticipated Enrollment: 190 participants
• Allocation: Randomized
• Intervention Model: Single Group Assignment
• Intervention Model Description: Two groups of subjects (young, older) participate in twelve experiments; experimental conditions consist of six different combinations of temperature and humidity and are performed at two different exercise intensities. The experiments are conducted in randomized order and are separated by a minimum of three days. A subgroup of older adults will be asked to complete all trials after taking daily low-dose aspirin for seven days, and aspirin will be continued until all trials are complete.Two groups of subjects (young, older) participate in twelve experiments; experimental conditions consist of six different combinations of temperature and humidity and are performed at two different exercise intensities. The experiments are conducted in randomized order and are separated by a minimum of three days. A subgroup of older adults will be asked to complete all trials after taking daily low-dose aspirin for seven days, and aspirin will be continued until all trials are complete.
• Masking: None (Open Label)
• Primary Purpose: Basic Science
• Official Title: Identification of Critical Thermal Environments for Aged Adults
• Actual Study Start Date: Dec 30, 2020
• Anticipated Primary Completion Date: Feb 28, 2025
• Anticipated Study Completion Date: Feb 28, 2025

Arms and Interventions

Arm	Intervention/Treatment
Experimental: Critical Environmental Limits Subjects will perform exercise at ~200-300W with ambient temperature or humidity increasing every 5 min throughout the trial until core temperature begins to rise.	Other: Control; All participants will be tested with no treatment.
Experimental: Aspirin Supplementation After a minimum of 7 days of daily, low-dose aspirin ingestion, older subjects will repeat critical environmental limits trials. As before, subjects will perform exercise at ~200-300W with ambient temperature or humidity increasing every 5 min throughout the trial until core temperature begins to rise.	Drug: Low dose ASA; A sub-group of older adults will be re-tested after 7 days of treatment with low-dose aspirin.; Other Names: Low-dose aspirin

Outcome Measures

Primary Outcome Measures

1. Temperature and humidity limits for maintaining stable core temperature [Through study completion, an average of 1 year.]

   Core temperature will be measured throughout exercise. The point at which heat stress becomes uncompensable will be determined for each environmental and exercise condition by assessing the combination of temperature and humidity at which core temperature begins to rise.

Secondary Outcome Measures

1. Core temperature [Continuous throughout visit until completion of exercise; an average of 2 hours.]

   Core temperature will be monitored throughout each experimental visit

2. Sweat rate [Immediately before and immediately after exercise.]

   Sweat rate will be determined by measuring nude body mass before and after each experimental visit

3. Skin temperature [Continuous throughout visit until completion of exercise; an average of 2 hours.]

   Skin temperature will be monitored throughout each experimental visit

Eligibility Criteria

Criteria

• Ages Eligible for Study: 18 Years to 85 Years
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: Yes

Inclusion Criteria:

• Non-obese with body mass index <30

• HbA1C <5.7%

• Low density lipoprotein cholesterol <180 mg/dl

• Between the 20th and 80th percentiles for sex- and age-appropriate VO2max according to the American College of Sports Medicine 10th edition Guidelines for Exercise Testing and Prescription

Exclusion Criteria:

• Tobacco use

• Medications that affect thermoregulatory or cardiovascular responses to exercise

• Any contraindications to low intensity physical activity on the Physical Activity Readiness Questionnaire

• Any mobility restrictions that interfere with low intensity physical activity

• Pregnant or planning to become pregnant in the next 12 months

• Prior diagnosis of cancer, cardiovascular disease, diabetes, or metabolic syndrome

• Illegal/recreational drug use

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	Noll Laboratory	University Park	Pennsylvania	United States	16802

Sponsors and Collaborators

• Penn State University

Investigators

• Principal Investigator: W. Larry Kenney, Ph.D., The Pennsylvania State University

Study Documents (Full-Text)

None provided.

More Information

Publications

None provided.

• Responsible Party: W. Larry Kenney, Professor, Penn State University
• ClinicalTrials.gov Identifier: NCT04284397
• Other Study ID Numbers: Study14062
• First Posted: Feb 25, 2020
• Last Update Posted: Feb 25, 2022
• Last Verified: Feb 1, 2022

• Individual Participant Data (IPD) Sharing Statement: No
• Plan to Share IPD: No
• Studies a U.S. FDA-regulated Drug Product: Yes
• Studies a U.S. FDA-regulated Device Product: No
• Product Manufactured in and Exported from the U.S.: Yes
• Keywords provided by W. Larry Kenney, Professor, Penn State University: Aging; Thermoregulation; Heat stress
• Additional relevant MeSH terms: Aspirin

Study Results

No Results Posted as of Feb 25, 2022