Fitness and Longevity in Exercise (FLEX)

The study objective was to determine the safety and efficacy of aerobic exercise in older HIV-infected men in a randomized trial comparing different levels of exercise intensity.

Study Overview

• Status: Completed
• Conditions: Aging; HIV-1-infection
• Intervention / Treatment: Behavioral: Exercise training

Detailed Description

The study was a randomized trial of moderate-intensity versus high-intensity aerobic exercise (AEX) training in older HIV-infected adults. Funding was provided by K23 AG024896 (PI, Oursler) and the UMB Claude D. Pepper Older Americans Independence Center P60 AG12583 (PI, Goldberg).

The central hypothesis was that high-intensity AEX training is well-tolerated and significantly increases aerobic capacity in older HIV-infected adults.

The study met its objectives:

1. Scientific AIMS met:

   1. High-intensity AEX training significantly increases aerobic capacity
   2. Both moderate-intensity and high-intensity AEX training improve ambulatory function and endurance.
   3. Activity of skeletal muscle oxidative enzymes is reduced, and associated with aerobic capacity.

2. Feasibility Objectives met:

   1. AEX training is safe and well-tolerated in older HIV-infected adults.
   2. Skeletal muscle punch biopsy is safe and well-tolerated in older HIV-infected adults.
   3. Preliminary data was collected on plasma biomarkers of inflammation.

• Study Type: Interventional
• Enrollment (Actual): 31
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• HIV+
• stable combination antiretroviral therapy (cART)

Exclusion Criteria:

• AIDS defining conditions in the prior six months
• Conditions that increase the risk of exercise training per the American College of Sports Medicine (ACSM)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Moderate-intensity aerobic exercise; In the moderate-intensity aerobic exercise group, participants performed a self-paced 1-mile walk (3-5 METs) on an indoor track in the same exercise center as the high-intensity exercise group. Initial sessions lasted 20-30 minutes and were increased weekly to 45 minutes in parallel to the duration of the high-intensity exercise group.	Behavioral: Exercise training; Participants attended center-based exercise sessions three times per week at the research exercise training facility located at the Baltimore VA Medical Center. All exercise training was performed under the supervision of research exercise physiologists. Heart rate (HR) was measured continuously during each session using a Polar HR watch and chest strap allowing for assessment and maintenance of treatment fidelity. Exercise logs included details on exercise type, duration, time in target heart rate zone, blood pressure and perceived intensity during each training session.
Experimental: High-intensity aerobic exercise; In the high-intensity aerobic exercise group, exercise training was performed on a motorized treadmill with occasional substitution with the elliptical machine as needed for joint pain. Target heart rate was based on the baseline treadmill test and was calculated as percentage of the heart rate reserve (HRR=maximal HR-resting HR). Initially, participants trained for 20-30 minutes at 50-60% of HRR. Duration and intensity was increased by 10% weekly so that within 5-7 weeks the aerobic exercise sessions lasted 30-45 minutes at 70-85% of HRR and at the end of the 16 weeks lasted 40-45 minutes at 75-90% of HRR.	Behavioral: Exercise training; Participants attended center-based exercise sessions three times per week at the research exercise training facility located at the Baltimore VA Medical Center. All exercise training was performed under the supervision of research exercise physiologists. Heart rate (HR) was measured continuously during each session using a Polar HR watch and chest strap allowing for assessment and maintenance of treatment fidelity. Exercise logs included details on exercise type, duration, time in target heart rate zone, blood pressure and perceived intensity during each training session.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline Cardiorespiratory Fitness at 16 weeks	Cardiorespiratory Fitness measured by VO2peak	16-weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline Six-minute walk distance at 16 weeks	Distance walked at normal pace in 6 minutes	16-weeks
Change from baseline body composition at 16 weeks	body composition measured as total and regional lean tissue and fat mass (DXA)	16-weeks
Change from baseline exercise endurance at 16 weeks	exercise endurance measured as time on treadmill during modified Bruce protocol	16-weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
skeletal muscle oxidative function	activity of enzymes in oxidative function from muscle biopsy	baseline

Collaborators and Investigators

• Sponsor: University of Maryland, Baltimore
• Investigators: Principal Investigator: Krisann Oursler, MD, University of Maryland, Baltimore

Publications and helpful links

General Publications

• Ortmeyer HK, Ryan AS, Hafer-Macko C, Oursler KK. Skeletal muscle cellular metabolism in older HIV-infected men. Physiol Rep. 2016 May;4(9):e12794. doi: 10.14814/phy2.12794.

Study record dates

Study Major Dates

• Study Start (Actual): July 19, 2007
• Primary Completion (Actual): October 29, 2010
• Study Completion (Actual): April 23, 2012

Study Registration Dates

• First Submitted: January 4, 2018
• First Submitted That Met QC Criteria: January 11, 2018
• First Posted (Actual): January 16, 2018

Study Record Updates

• Last Update Posted (Estimate): December 6, 2022
• Last Update Submitted That Met QC Criteria: December 2, 2022
• Last Verified: December 1, 2022

More Information

Terms related to this study

• Keywords: Intervention; Exercise training; Aerobic capacity
• Other Study ID Numbers: HP-00042601

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No
• IPD Plan Description: Data, which include PHI, are available from the University of Maryland School of Medicine Institutional Review Board for researchers who meet the criteria for access to confidential data.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No