The Acute T-Rex (Timing of Resistance Exercise) Study

Timing (AM v PM) of Acute Resistance Exercise on Glycemic Control in Older Adults: The Acute T-Rex Study

The primary aim of this study is to evaluate if a single bout of AM vs PM resistance exercise has different effects on insulin sensitivity and sleep. A randomized cross-over trial be used to compare resistance exercise at two different times of the day. Each condition will take place in a laboratory setting. Each condition will consist of exercise, overnight sleep, and oral glucose tolerance tests the following day. The AM exercise will occur ~1.5 hours after habitual wake, and PM exercise will occur ~11 hours after habitual wake. After a 2-6 week washout, participants will complete the other condition. The hypothesis is that PM exercise will be more beneficial than AM exercise in improving insulin sensitivity. This study could identify if there is a better time of day to perform resistance exercise to decrease risk of developing Type 2 Diabetes Mellitus.

Study Overview

• Status: Recruiting
• Conditions: Diabetes Mellitus, Type 2; Insulin Resistance; Glucose Intolerance; Sleep Disturbance; Overweight or Obesity; Insulin Sensitivity
• Intervention / Treatment: Behavioral: Resistance Exercise Timing

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

Contacts and Locations

• Study Contact: Name: Tanya M Halliday, PhD; Phone Number: 801-213-1364; Email: tanya.halliday@utah.edu
• Study Contact Backup: Name: Study Email Study Email; Phone Number: 8014487897; Email: trexstudy@utah.edu

Study Locations

• United States
  • Utah
    • Salt Lake City, Utah, United States, 84112
      • Recruiting
      • University of Utah HPER E Buildling
      • Contact: Jason V Thomas, MS; Email: jason.v.thomas@utah.edu
      • Principal Investigator: Tanya M Halliday, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Men and women, all ethnicities, aged 50-74 years
• BMI ≥25 kg/m² and <45 kg/m²
• Weight stable (less than 5% change in the past 6 months)
• Generally healthy individuals
• Not meeting recommended activity guidelines for aerobic or resistance exercise

Exclusion Criteria:

• Uncontrolled cardiovascular, metabolic, renal, or pulmonary disease
• Cancer treatment in the past 5 years
• Untreated thyroid disease or other medical conditions affecting weight or energy metabolism
• Current use of weight loss medication or other medications likely to impact energy balance
• Bariatric surgery or extensive bowel resection in the past 2 years
• Current or recent history (past 2 years) of eating disorder
• Diagnosis of insomnia, sleep apnea, or other sleep and circadian disorders
• Non-English speaking
• HbA1c >6.5%

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: AM Resistance Exercise; Resistance Exercise intervention taking place in the AM	Behavioral: Resistance Exercise Timing; 1 resistance exercise session consisting of 3 sets, 10 repetitions per set, on 12 different exercises; Other Names: Exercise; Strength-Training; Weightlifting
Experimental: PM Resistance Exercise; Resistance Exercise intervention taking place in the PM	Behavioral: Resistance Exercise Timing; 1 resistance exercise session consisting of 3 sets, 10 repetitions per set, on 12 different exercises; Other Names: Exercise; Strength-Training; Weightlifting

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Insulin sensitivity	Insulin sensitivity will be calculated using the Matsuda Insulin Sensitivity Index	1 day

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sleep Duration	Sum of time spent in stage 1, stage 2, stage 3 and rapid eye movement stage (REM) as assessed via polysomnography.	1 day

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sleep Staging	Time spent in stage 1, stage 2, stage 3 and REM sleep assessed by polysomnography.	1 day
Sleep Quality	As assessed via Pittsburg Sleep Quality Index Questionnaire (scale:0-21, higher scores=worse outcome) and polysomnography	1 day
Sleep Efficiency	Ratio of time in bed vs time asleep	1 day
Muscular Strength	Muscular strength as assessed via 10 repetition maximum test	1 day
Perceived Hunger	Visual Analog Scales (scale: 0-100)	1 day
Perceived Fullness	Visual Analog Scales (scale: 0-100)	1 day
Perceived Prospective Food Consumption	Visual Analog Scales (scale: 0-100)	1 day
Glucose Area Under Curve	Mathematical calculation using fasting, 10,20,30,60,90,120 min blood glucose	1 day
Insulin Area Under Curve	Mathematical calculation using fasting, 10,20,30,60,90,120 min blood insulin	1 day

Collaborators and Investigators

• Sponsor: University of Utah

Study record dates

Study Major Dates

• Study Start (Actual): November 15, 2023
• Primary Completion (Estimated): December 31, 2025
• Study Completion (Estimated): December 31, 2025

Study Registration Dates

• First Submitted: January 31, 2024
• First Submitted That Met QC Criteria: April 10, 2024
• First Posted (Actual): April 15, 2024

Study Record Updates

• Last Update Posted (Actual): April 3, 2025
• Last Update Submitted That Met QC Criteria: April 1, 2025
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Keywords: Sleep; Circadian Rhythm; Resistance Exercise; Strength-training
• Additional Relevant MeSH Terms: Endocrine System Diseases; Nutrition Disorders; Metabolic Diseases; Overnutrition; Body Weight; Glucose Metabolism Disorders; Diabetes Mellitus; Hyperinsulinism; Hyperglycemia; Overweight; Diabetes Mellitus, Type 2; Insulin Resistance; Glucose Intolerance
• Other Study ID Numbers: 00156659

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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