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ObesityNCT02532725

Work-Related Effects of Heat, Activity, and Fat in Middle Aged Men

An observational study of Obesity and Gender, run by Freeman-Sheldon Research Group, Inc. at 1 site in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

Obesity is associated with many undesirable health effects and disease, and middle age is associated with increased risk for disease. Unfortunately, while others have looked at the effects of obesity, gender, and middle age, the combined effects of obesity and middle age on men's ability to do work in hot industrial… Read more about this study

Who is it for?
Ages 35 to 55 years, men onlyHealthy volunteers can take part
Conditions the study is for
Obesity, Gender, Problem of Aging
What is being tested?
Cardiopulmonary Exercise Stress Test, Body Composition Evaluation and Pre-Exercise Risk Assessment
Type of treatment
Surgery or procedure
How many people
12 participants
Where
1 siteUnited States
Study dates
Jun 1972to Dec 1972
Phase
Observational
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 35 to 55 years
  • Men only
  • Healthy volunteers accepted
  • Adult

Study population: Lean and obese middle aged men unaccustomed to working in hot industrial conditions

Who may be able to join

  • Able and willing to give consent and to complete minimum study procedures, as defined by the protocol
  • Non-invasive resting blood pressure within normal limits
  • Resting electrocardiogram within normal limits
  • Hematology and Chemistry (blood) panels within normal limits
  • Urinalysis (pH, glucose, and protein) within normal limits
  • Negative cardiopulmonary stress test
  • Absence of acute or chronic metabolic, cardiovascular, pulmonary, and orthopedic disease

Who cannot join

  • Unable or unwilling to give consent or to complete minimum study procedures, as defined by the protocol
  • Non-invasive resting blood pressure outside normal limits
  • Resting electrocardiogram outside normal limits
  • Hematology and Chemistry (blood) panels outside normal limits
  • Urinalysis (pH, glucose, and protein) outside normal limits
  • Positive cardiopulmonary stress test
  • Presence of acute or chronic metabolic, cardiovascular, pulmonary, and orthopedic disease

Trial locations and contacts

1 site in 1 country.

United States1 site
  • Freeman-Sheldon Research Group, Inc. Headquarters

    Buckhannon, West Virginia, 26201

Other trials in United States

About this study

Official title: Relationship of Occupational Heat Stress Endurance, Work, and Percentage of Body Fat in Middle Aged Men

Obesity is associated with many undesirable health effects and disease, and middle age is associated with increased risk for disease. Unfortunately, while others have looked at the effects of obesity, gender, and middle age, the combined effects of obesity and middle age on men's ability to do work in hot industrial environments have not been satisfactorily investigated.

This small study evaluates the heat tolerance of lean and obese middle aged men both while exercising and resting and the ways in which each compensate for and dissipate increasing environmental heat and heat generated by the body while exercising.

As obesity is a worldwide public health crisis and as populations in many industrialized nations age, it is important to understand the combined effects of obesity and middle age for men on their ability to safely work in hot environments. Such information will permit establishing and revising of safe work standards and inform public health outreach to the target population, itself.

Read the detailed description

The present study was initially approved by and conducted at The Pennsylvania State University in 1972 for the senior author's (Rodger J McCormick) D.Ed. thesis in Biological Sciences; funding support was provided by the US National Institute of Arthritis, Metabolism, and Digestive Diseases Grant AM-08311 and National Institutes of Health Grant 01748. Data re-analysis and representation of that study was first approved in 2011 by and conducted at the FSRG deGruyter-McKusick Institute of Health Sciences for partial fulfillment of an MS in Clinical and Applied Physiology being pursued by the junior author (Mikaela I Poling). No funding was received for this use of existing data.

Importance of Present Study:

Several heat tolerance studies, including Kenny, Gagnon, Dorman, Hardcastle, and Joy (2010), have indicated that middle-age men can perform hard work in hot environments nearly as well as younger men. Dufour and Candas (2007), in comparing passive heat responses and sudomotor function in young, middle aged, and older men, found only local, not global, decreases in sweat gland output in the two older groups, suggesting at least some significant preservation of sudomotor function. Since most studies employed subjects with lean normal body types, their results in terms of physiological reactions to heat stress may not be applicable to obese middle aged men. Other studies have demonstrated degraded heat stress exercise capacity in obese persons.

Within high heat stress areas such as in the steel, fiberglass, aluminium, mining, professional sports, and defense industries, lean and obese middle aged men can readily be observed performing the same work task in the same hot environment. Little attention has been given to differences between the lean and obese middle aged men in their physiological responses to the combination of internal heat production from the work task performed and the heat load imposed from the external environment.

In the present study, occupational heat stress endurance differences between lean and obese middle aged men and effect of obesity are investigated under laboratory simulated conditions to test the following hypotheses: (1) with greater baseline cardiovascular demands, it is expected that obese middle aged men will have reduced environmental heat tolerance and will gain and store more total heat; (2) poorer environmental heat tolerance of obese middle aged men will be greatly magnified by work (producing added metabolic heat); (3) lean middle aged men will thermoregulate well; (4) lean middle aged men will show few, if any, major signs of inability to compensate for added cardiovascular demands; (5) obese middle aged men will be functioning at a higher percentage of their maximal ventilation of expired oxygen; and (6) obese middle aged men will have poorer pulmonary fitness, as measured by maximal ventilation of expired oxygen, than lean middle aged men.

Being tested
Cardiopulmonary Exercise Stress Test, Climatic-Controlled Cardiopulmonary Exercise Stress Test, Body Composition Evaluation, Pre-Exercise Risk Assessment
Keywords
heat stress response, cardiopulmonary exercise test, men, middle aged, heat-shock response
Medical subject headings
Obesity, Coitus, Multiple Endocrine Neoplasia Type 1

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Cardiopulmonary Exercise Stress TestProcedure or surgery

    Also called Progressive Exercise Test, Graded Exercise Test, Stress Test

    Test preceded by warm-up treadmill walking 5 min at 4.8 km/h, 5% grade with a 1 min sitting rest period. Test, then, begins at 4.8 km/h, 2.5% grade with incremental grade increases every 2 min until exhaustion. Ambient environment is maintained at neutral, with effective temperature of 19-21° C. Heart, lungs, temperature, and sweating is monitored during testing.

  • Climatic-Controlled Cardiopulmonary Exercise Stress TestProcedure or surgery

    Also called Environmental Chamber Exercise Test

    Test includes 30 min walking bouts on the treadmill, with two 5 min sitting rest periods between bouts (Rest I and Rest II) and 15 min sitting recovery period (Rest III), in effective temperatures of 21.1 (baseline), 26.7, 29.4, 32.2, and 35.0° C. Heart, lungs, temperature, and sweating is monitored during testing.

  • Body Composition EvaluationProcedure or surgery

    Multiple methods are used to accurately estimate percentage of body mass (weight) composed of fat, muscle, bone, and other connective tissues. Four different methods, including caliper and hydrostatic (underwater weighing) are used in this study to ensure an accurate estimation.

  • Pre-Exercise Risk AssessmentProcedure or surgery

    Also called Pre-Participation Examination

    Includes non-invasive measurements of body functioning, a physical examination by a physician, and blood and urine testing to select subjects who can exercise with relative safety.

Study groups in NCT02532725
Study groupRoleWhat they receive
LeanMen aged 35-55 years, having <20% body fat
Receives: Procedure: Cardiopulmonary Exercise Stress Test; Procedure: Climatic-Controlled Cardiopulmonary Exercise Stress Test; Procedure: Body Composition Evaluation; Procedure: Pre-Exercise Risk Assessment
ObeseMen aged 35-55 years, having >29% body fat
Receives: Procedure: Cardiopulmonary Exercise Stress Test; Procedure: Climatic-Controlled Cardiopulmonary Exercise Stress Test; Procedure: Body Composition Evaluation; Procedure: Pre-Exercise Risk Assessment

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Core (Rectal) Temperature Change with Exercise Level and Increased Heat Load

    Failure to maintain rectal temperature within 0.15° C of subject baseline for interval from end of exercise Bout 2 to Bout 3.

    Measured: Evaluated during each session at rest and while exercising, with sessions lasting approximately 165-170 min

  2. Oxygen Consumption Change with Exercise Level and Increased Heat Load

    Oxygen consumption, measured by ventilation of expired oxygen, is used as a measure of physiological strain imposed by metabolic needs during exercise and exaggerated by obesity.

    Measured: Evaluated near the end of Exercise Bout 1 (2 min) and 3 (2 min)

  3. Heart rate Change with Exercise Level and Increased Heat Load

    Increased heart rate, measured electrocardiographically, is used as an index of cardiovascular strain imposed by needs during exercise and exaggerated by obesity.

    Measured: Evaluated during each session at rest and while exercising, with sessions lasting approximately 165-170 min

  4. Difference in Routine and Maximal Ventilation of Expired Oxygen at Neutral Ambient Temperature

    Warm-up approximates steady, normal work, while the progressive portion of the text places maximal metabolic burden on the subject in order to measure upper limit of heart and lung function

    Measured: Cardiopulmonary Stress Test, during the last 1 min of warm-up and at end of progressive portion as volitional exhaustion approached

Secondary outcomes (5)
  1. Perceived Exertion Change with Exercise Level and Increased Heat Load

    Increased perceived exertion is used as an index of fatigue, an indirect indicator of physiological strain.

    Measured: Evaluated during each session at rest and while exercising, with sessions lasting approximately 165-170 min

  2. Non-Invasive Arterial Blood Pressure Change with Exercise Level and Increased Heat Load

    Increased non-invasive arterial blood pressure rate is used as an index of cardiovascular strain imposed by needs during exercise, is an important indicator of possible onset of shock, and exaggerated by obesity.

    Measured: Evaluated at rest before exercise (20-25 min) and at Rest I (5 min), II (5 min), and III (15 min)

  3. Heart Rhythm Change with Exercise Level and Increased Heat Load

    Heart rhythms, monitored by electrocardiograph, are used as an index of cardiovascular strain imposed by needs during exercise and could be exaggerated by obesity.

    Measured: Evaluated during each session at rest and while exercising, with sessions lasting approximately 165-170 min

  4. Metabolic Rate Change with Exercise Level and Increased Heat Load

    Rate of energy usage of the body calculated from ventilation of expired oxygen values

    Measured: Evaluated near the end of Exercise Bout 1 (2 min) and Bout 3 (2 min).

  5. Heat Load Change with Exercise Level and Increased Environmental Temperature

    Calculated metabolic and environmental heat gain minus heat loss

    Measured: During Rest I (5 min), II (5 min), and III (15 min)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted26 Aug 2015 (estimated)
  2. Study startJun 1972
  3. Primary completionDec 1972
  4. Study completionDec 1972

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Observational
Observational model
Case-control
Time perspective
Prospective
Enrolment
12 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT02532725
Sponsor's protocol ID
U1111-1120-6134
Status last verified
Aug 2015
First submitted
19 Aug 2015
Last updated
26 Aug 2015
Results posted
No
Data monitoring committee
No

Publications

  • Haymes EM, McCormick RJ, Buskirk ER. Heat tolerance of exercising lean and obese prepubertal boys. J Appl Physiol. 1975 Sep;39(3):457-61. doi: 10.1152/jappl.1975.39.3.457.

    PubMed 1176412
  • Kenny GP, Gagnon D, Dorman LE, Hardcastle SG, Jay O. Heat balance and cumulative heat storage during exercise performed in the heat in physically active younger and middle-aged men. Eur J Appl Physiol. 2010 May;109(1):81-92. doi: 10.1007/s00421-009-1266-4. Epub 2009 Nov 3.

    PubMed 19885672
  • Dufour A, Candas V. Ageing and thermal responses during passive heat exposure: sweating and sensory aspects. Eur J Appl Physiol. 2007 May;100(1):19-26. doi: 10.1007/s00421-007-0396-9. Epub 2007 Jan 23.

    PubMed 17242944

Questions about this trial

What is this clinical trial studying?

An observational study of Obesity and Gender, run by Freeman-Sheldon Research Group, Inc. at 1 site in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 7 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 26 Aug 2015. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Core (Rectal) Temperature Change with Exercise Level and Increased Heat Load (time frame: Evaluated during each session at rest and while exercising, with sessions lasting approximately 165-170 min). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT02532725, which also lists 3 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 26 Aug 2015.

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