Clinical trial NCT04733287: Heat Therapy and Muscle Function Study
Official title: Improving Critical Power and Muscle Function in Older Adults With Heat Therapy
Study type: INTERVENTIONAL
Overall status: UNKNOWN
Phase: NA
Conditions: Exercise Intolerance
Aging
Heat Therapy
High Intensity Interval Training
Lead sponsor: Brigham Young University
Sponsor class: OTHER
First posted: 2021-02-02
Enrollment: 148
Sex: ALL
Minimum age (years): 18
Maximum age (years): 95
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
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

Brief summary: 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.


Eligibility criteria: 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

Primary outcomes:
measure: Muscle Critical Power
timeFrame: 3-8 weeks
Secondary outcomes:
measure: Resistance Artery Function
timeFrame: 3-8 weeks
measure: Maximum Exercise Blood Flow
timeFrame: 3-8 weeks
measure: Muscle Fiber Size
timeFrame: 3-8 weeks
measure: Muscle Mitochondrial Function
timeFrame: 3-8 weeks
measure: Vastus Lateralis Cross-Sectional Area
timeFrame: 3-8 weeks
Other outcomes:
Locations:
city: Provo
country: United States
facility: Brigham Young University
state: Utah
Study officials:
affiliation: Brigham Young University
name: Jayson Gifford, Ph.D.
role: STUDY_DIRECTOR
affiliation: Brigham Young Univeristy
name: Robert Hyldahl, Ph.D.
role: PRINCIPAL_INVESTIGATOR
References:
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citation: Hafen PS, Preece CN, Sorensen JR, Hancock CR, Hyldahl RD. Repeated exposure to heat stress induces mitochondrial adaptation in human skeletal muscle. J Appl Physiol (1985). 2018 Nov 1;125(5):1447-1455. doi: 10.1152/japplphysiol.00383.2018. Epub 2018 Jul 19.
citation: Hafen PS, Abbott K, Bowden J, Lopiano R, Hancock CR, Hyldahl RD. Daily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilization. J Appl Physiol (1985). 2019 Jul 1;127(1):47-57. doi: 10.1152/japplphysiol.01098.2018. Epub 2019 May 2.
citation: Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM. Critical Power: An Important Fatigue Threshold in Exercise Physiology. Med Sci Sports Exerc. 2016 Nov;48(11):2320-2334. doi: 10.1249/MSS.0000000000000939.
citation: Helgerud J, Hoydal K, Wang E, Karlsen T, Berg P, Bjerkaas M, Simonsen T, Helgesen C, Hjorth N, Bach R, Hoff J. Aerobic high-intensity intervals improve VO2max more than moderate training. Med Sci Sports Exerc. 2007 Apr;39(4):665-71. doi: 10.1249/mss.0b013e3180304570.
citation: Brunt VE, Howard MJ, Francisco MA, Ely BR, Minson CT. Passive heat therapy improves endothelial function, arterial stiffness and blood pressure in sedentary humans. J Physiol. 2016 Sep 15;594(18):5329-42. doi: 10.1113/JP272453. Epub 2016 Jun 30.
citation: Kim K, Reid BA, Casey CA, Bender BE, Ro B, Song Q, Trewin AJ, Petersen AC, Kuang S, Gavin TP, Roseguini BT. Effects of repeated local heat therapy on skeletal muscle structure and function in humans. J Appl Physiol (1985). 2020 Mar 1;128(3):483-492. doi: 10.1152/japplphysiol.00701.2019. Epub 2020 Jan 23.