Cooling Strategies for Older Adults in the Heat

Acute and Chronic Interventions to Improve Heat Loss During Uncompensable Humid Heat Stress in Older Adults

The earth's climate is warming, and the number of heat waves has increased in recent years. At the same time, the number of adults over the age of 65 is growing. Humans sweat and increase blood flow to the skin to cool their body when they get hot. Older adults do not do this as well as young adults. This makes it harder to safely be in warm and/or humid conditions. It is important to learn about cooling strategies for older adults to safely be in warm and/or humid conditions.

There is compelling evidence that intermittent hand and forearm cold-water immersion effectively reduces the rise of core temperature during heat stress in older adults. However, it is still unknown if this is an effective cooling strategy for older adults. Furthermore, our laboratory has shown that folic acid supplementation improves blood flow responses in older adults. This may be beneficial to older adults during heat stress.

Study Overview

• Status: Not yet recruiting
• Conditions: Aging
• Intervention / Treatment: Other: Intermittent cold-water hand and forearm immersion; Other: No intermittent cold-water hand and forearm immersion

Detailed Description

Subjects sign an informed consent form and undergo a medical screening prior to participation. The screening includes a physical exam, anthropometry, chemical and lipid profiles.

Subjects participate in 4 experimental trials, 2 while on folic acid supplementation and 2 while on placebo. The order of treatment (folic acid supplementation or placebo) is randomized. Participants will place their hands and forearms in cold tap water intermittently for one of the two trials for each treatment. The order of the hand and forearm immersion trial is randomized for each treatment. The trials are separated by at least five days. For each experiment, core temperature, heart rate, blood pressure, skin temperature, and sweat rate are measured. Each experimental visit will last 2 hours.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: W. Larry Kenney, Ph.D.; Phone Number: 814-863-1672; Email: w7k@psu.edu
• Study Contact Backup: Name: Rachel Cottle, MS; Email: rmc5808@psu.edu

Study Locations

• United States
  • Pennsylvania
    • University Park, Pennsylvania, United States, 16802
      • Noll Laboratory
      • Contact: W. Larry Kenney, Ph.D.; Phone Number: 814-863-1672; Email: w7k@psu.edu
      • Contact: Rachel Cottle, MS; Email: rmc5808@psu.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Adults aged 65 and older
• English proficiency

Exclusion Criteria:

• Chron's disease, diverticulitis, or similar gastrointestinal disease
• Abnormal resting exercise electrocardiogram (ECG)
• Tobacco use
• High-risk determined by the Atherosclerotic Cardiovascular Disease (CVD) Risk Factor Assessment
• Antiepileptic or antiseizure medications
• Methotrexate

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Folic acid supplementation; 5 mg/day folic acid for 6-7 weeks	Other: Intermittent cold-water hand and forearm immersion; Participants will be seated at rest in a hot and humid environment. At 2 time points in the experiment, participants will place their hands and forearms in a bucket of cold tap water for 10 minutes.; Other: No intermittent cold-water hand and forearm immersion; Participants will be seated at rest in a hot and humid environment.
Placebo Comparator: Control; Cellulose placebo tablet for 6-7 weeks	Other: Intermittent cold-water hand and forearm immersion; Participants will be seated at rest in a hot and humid environment. At 2 time points in the experiment, participants will place their hands and forearms in a bucket of cold tap water for 10 minutes.; Other: No intermittent cold-water hand and forearm immersion; Participants will be seated at rest in a hot and humid environment.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Core temperature	Core temperature will be monitored throughout each 2 hour experimental visit.	A slope of core temperature for each experimental aim is calculated and reported through study completion, an average of 1 year.
Heart rate	Heart rate will be monitored continuously throughout each 2 hour experimental visit.	A slope of heart rate for each experimental aim is calculated and reported through study completion, an average of 1 year.
Blood Pressure	Blood pressures will be taken every 10 minutes throughout each 2 hour experimental visit.	Blood pressure for each experimental aim is recorded and reported through study completion, an average of 1 year.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body Mass	Body weight measured on a scale	Baseline immediately before beginning the experimental visit and then once again at the end of the 2 hour experimental visit
Skin Temperature	Average mean skin temperature	Mean skin temperature for each experimental aim is calculated and reported through study completion, an average of 1 year

Collaborators and Investigators

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

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2024
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 1, 2026

Study Registration Dates

• First Submitted: March 19, 2024
• First Submitted That Met QC Criteria: April 4, 2024
• First Posted (Actual): April 5, 2024

Study Record Updates

• Last Update Posted (Actual): April 5, 2024
• Last Update Submitted That Met QC Criteria: April 4, 2024
• Last Verified: April 1, 2024

More Information

Terms related to this study

• Keywords: Aging; Thermoregulation; Heat Stress
• Other Study ID Numbers: STUDY24458

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No