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

NCT02532725 | Completed

• 1 other identifier: U1111-1120-6134
• Study Type: observational
• Target: 12
• Locations: 1 country
• Sites: 1

Brief 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 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.

Conditions

Obesity; Gender; Problem of Aging

Keywords

heat stress response; cardiopulmonary exercise test; men; middle aged; heat-shock response

Outcome Measures

Primary Outcomes (4)

• 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.

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

• 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.

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

• 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.

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

• 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

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

Secondary Outcomes (5)

• Perceived Exertion Change with Exercise Level and Increased Heat Load

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

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

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

• Heart Rhythm Change with Exercise Level and Increased Heat Load

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

• Metabolic Rate Change with Exercise Level and Increased Heat Load

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

• Heat Load Change with Exercise Level and Increased Environmental Temperature

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

Other Outcomes (2)

• Body Composition

  Evaluated before exercise (20 min)

• Age at Death or Current Age

  up to 526 months

Study Arms (2)

Lean

Men aged 35-55 years, having \<20% body fat

Procedure: Cardiopulmonary Exercise Stress Test; Procedure: Climatic-Controlled Cardiopulmonary Exercise Stress Test; Procedure: Body Composition Evaluation; Procedure: Pre-Exercise Risk Assessment

Obese

Men aged 35-55 years, having \>29% body fat

Procedure: Cardiopulmonary Exercise Stress Test; Procedure: Climatic-Controlled Cardiopulmonary Exercise Stress Test; Procedure: Body Composition Evaluation; Procedure: Pre-Exercise Risk Assessment

Interventions

Cardiopulmonary Exercise Stress Test PROCEDURE

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.

Also known as: Progressive Exercise Test, Graded Exercise Test, Stress Test

Lean; Obese

Climatic-Controlled Cardiopulmonary Exercise Stress Test PROCEDURE

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.

Also known as: Environmental Chamber Exercise Test

Lean; Obese

Body Composition Evaluation PROCEDURE

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.

Lean; Obese

Pre-Exercise Risk Assessment PROCEDURE

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.

Also known as: Pre-Participation Examination

Lean; Obese

Eligibility Criteria

• Age: 35 Years - 55 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)
• Sampling Method: Non-Probability Sample

Study Population

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

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Freeman-Sheldon Research Group, Inc.: lead

Study Sites (1)

Freeman-Sheldon Research Group, Inc. Headquarters

Buckhannon, West Virginia, 26201, United States

Location

Related Publications (3)

• 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.

  PMID: 1176412 BACKGROUND

• 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.

  PMID: 19885672 BACKGROUND

• 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.

  PMID: 17242944 BACKGROUND

Related Links

• Freeman-Sheldon Research Group, Inc. (Sponsor's general website)

MeSH Terms

Conditions

Obesity; Coitus; Multiple Endocrine Neoplasia Type 1

Interventions

Exercise Test

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Sexual Behavior; Behavior; Multiple Endocrine Neoplasia; Endocrine Gland Neoplasms; Neoplasms by Site; Neoplasms; Neoplasms, Multiple Primary; Neoplastic Syndromes, Hereditary; Genetic Diseases, Inborn; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Endocrine System Diseases

Intervention Hierarchy (Ancestors)

Heart Function Tests; Diagnostic Techniques, Cardiovascular; Diagnostic Techniques and Procedures; Diagnosis; Respiratory Function Tests; Diagnostic Techniques, Respiratory System; Ergometry; Investigative Techniques

Study Officials

• Rodger J McCormick, DEd

  Freeman-Sheldon Research Group, Inc.

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: CASE CONTROL
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 19, 2015
• First Posted: August 26, 2015
• Study Start: June 1, 1972
• Primary Completion: December 1, 1972
• Study Completion: December 1, 1972
• Last Updated: August 26, 2015

Record last verified: 2015-08

Locations

US (1)