Trials Today

Heat Therapy and Muscle Function Study

Purpose

Exercise tolerance decreases with age and a sedentary lifestyle. Muscle critical power (CP), is a sensitive measure of exercise tolerance that is more even more relevant to and predictive of endurance performance than VO2max. While recent evidence indicates that CP and muscle function decrease with aging, the cause of this decrease in CP and the best way to mitigate the decrease in CP are unknown. This study will: 1. Measure knee extensor CP in young and old individuals and determine the extent to which changes in muscle oxygen delivery (e.g. resistance artery function, maximum exercise blood flow), muscle mass and composition (e.g. whole-muscle size, muscle fiber cross-sectional area) and mitochondrial oxygen consumption (e.g. maximal coupled respiration of permeabilized fibers biopsied from the knee extensors) contribute to the decrease in CP with age. 2. Examine the effectiveness of two different therapies (1. High Intensity Interval Training, HIIT and 2. Muscle Heat Therapy) at improving muscle function and critical power in young and older adults. 3. Examine the impact of muscle disuse (2 weeks of leg immobilization), a potential contributor to the decrease in muscle function with aging, on muscle function and critical power and determine if heat therapy is an effective means of minimizing the impact of disuse on muscle function and critical power.

Conditions

Exercise Intolerance
Aging
Heat Therapy
High Intensity Interval Training

Eligibility

Eligible Ages: Between 18 Years and 95 Years
Eligible Genders: All
Accepts Healthy Volunteers: Yes

Inclusion Criteria

18-95 years of age - Currently no cardiovascular or metabolic disease (e.g. heart failure, diabetes) - ability to perform knee extension exercise

Exclusion Criteria

Pregnant - Current cardiovascular or metabolic disease (e.g. heart failure, diabetes) - participating in exercise training within the last 6 months - inability to perform knee extension exercise

Study Design

Phase: N/A
Study Type: Interventional
Allocation: Randomized
Intervention Model: Parallel Assignment
Intervention Model Description: Young (18-35 years) and Older (60+ years) will be randomly assigned to one of 3 different conditions (High Intensity Exercise Training of the Knee Extensors, Heat therapy of the Knee Extensors or Sham Heat therapy of the Knee Extensors). Muscle function will be measured before and after 6 weeks of the randomized treatment. A separate set of 40 young adults (18-35 years) will undergo 2 weeks of leg immobilization. Half of the subjects will receive daily heat therapy, while the other half will receive a sham heat therapy treatment. Muscle function and critical power will be measured before and after immobilization for both groups
Primary Purpose: Treatment
Masking: Single (Participant)
Masking Description: Subjects assigned to the heat therapy and the sham heat therapy will not know if they are truly receiving the heat therapy or not. The muscle heater (shortwave diathermy) will be placed on the muscle during each visit, but, unbeknownst to the heat and sham group, will not be turned on for the sham group.

Arm Groups

Arm	Description	Assigned Intervention
Experimental Effect of High Intensity Interval Training	Young and older subjects will participate in single-leg, high-intensity interval training of the right knee extensors (4 intervals of 4 minutes at 80% of max aerobic power with 4 minute rest intervals between, 3x per week for 6 weeks). Muscle function and knee extensor critical power will be measured before and after the 6 weeks of treatment.	Other: High Intensity Interval Training of the Knee Extensors Subjects will perform intense, single leg knee extension exercise 3 times a week for 6 weeks. Specifically, subjects will be seated in a custom knee extension ergometer and perform single leg, dynamic knee extension (similar to single leg cycling) as they perform the exercise. After a 6 minute warm-up at ~20% of that leg's maximum aerobic power (determined during a graded exercise test of single leg knee extension), subjects will perform 4 bouts of 4 minutes at ~80% of maximum aerobic power. Recovery of 4 minutes at ~40% will occur between each bout of exercise. A cool down will be provided at the end of exercise. In total, subjects will perform 40 minutes of single leg knee extension exercise, 3 times a week for 6 weeks. Maximum aerobic power (determined by a graded exercise test) will be determined again at 3 weeks to appropriately adjust the training intensity. Other names: HIIT
Experimental Effect of Muscle Heat Therapy	Young and older subjects will participate in single-leg,heat therapy training of a single leg ( quadriceps femoris, 120 minutes of shortwave diathermy to raise the muscle temperature to ~39C) 3 times a week for 6 weeks. Muscle function and knee extensor critical power will be measured before and after the 6 weeks of treatment.	Other: Muscle Heat Therapy Subjects will receive muscle heat therapy on the knee extensor muscles (short-wave diathermy) for 120 minutes for each visit. Specifically, subjects will lie supine while short-wave diathermy units (Megapulse II) will be placed on the quadriceps femoris and turned on to 800 pulses per second with a pulse duration of 400 microseconds. Our previous research (e.g. Hafen et al 2018- Repeated exposure to heat stress...) has indicated that this treatment raises muscle temperature to ~39C, a similar temperature induced by exercise. Other names: Short-wave Diathermy
Sham Comparator Effect of Sham Muscle Heat Therapy	Young and older subjects will participate in a sham treatment of single-leg,heat therapy training of the right knee extensors (120 minutes with shortwave diathermy unit positioned on leg, but not turned on) 3 times a week for 6 weeks. Muscle function and knee extensor critical power will be measured before and after the 6 weeks of treatment.	Other: Sham Heat Therapy Specifically, subjects randomly assigned to the sham group will receive the same treatment as the heat group (same number of visits and set up with the heating units applied to leg for 2 hours each visit) except, unbeknownst to either group, the heating units will never be turned on for the sham group.
Sham Comparator Effect of Immobilization with Daily Sham Heat Therapy	Young subjects (18-35 years) will undergo 2 weeks of leg immobilization while receiving 2 hours of a sham heat therapy treatment each day. For the sham treatment, the heating device will be applied to the limb, but, unbeknownst to the participant, it will not be turned on. Muscle function and knee extensor critical power will be measured before and after the 2 weeks of leg immobilization.	Other: Sham Heat Therapy Specifically, subjects randomly assigned to the sham group will receive the same treatment as the heat group (same number of visits and set up with the heating units applied to leg for 2 hours each visit) except, unbeknownst to either group, the heating units will never be turned on for the sham group.
Experimental Effect of Immobilization with Daily Heat Therapy	Young subjects (18-35 years) will undergo 2 weeks of leg immobilization while receiving 2 hours of heat therapy treatment each day. Heat therapy will consist of 120 minutes of shortwave diathermy to raise the quadriceps femoris muscle temperature to ~39C. Muscle function and knee extensor critical power will be measured before and after the 2 weeks of leg immobilization.	Other: Muscle Disuse Subjects will undergo 2 weeks of limb immobilization (a model of muscle disuse). Specifically, a knee brace will be placed on one of the subjects' legs and bent to a flexion of 60 degrees to prevent the foot from touching the ground while standing. Subjects will given a pair of crutches and asked to ambulate on crutches for 2 weeks, avoiding bearing any weight with the immobilized leg. Other names: Leg Immobilization

Recruiting Locations

Brigham Young University
Provo, Utah 84602

Contact:
Jayson Gifford, Ph.D.
801-422-3090
jaysongifford@byu.edu

More Details

NCT ID: NCT04733287
Status: Unknown status
Sponsor: Brigham Young University

Study Contact

Jayson Gifford, Ph.D.
8014223090
jaysongifford@byu.edu

Notice

Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.