Leg Heat Therapy in Elderly Individuals

Indiana Clinical and Translational Sciences Institute, American College of Sports Medicine Foundation

The number of persons aged ≥60 years in the United States is expected to nearly double, from 57 to 109 million between 2010 and 2050. These demographic changes will have profound implications for the healthcare system because advanced age is associated with a heightened risk of negative health outcomes, including disability and frailty. Few therapeutic strategies currently exist to combat the age-related decline in physical functioning that stems from the progressive loss of muscle mass and strength. The goal of the proposed experiments is to determine the benefits of home-based leg heat therapy (HT) in old, sedentary individuals. This novel approach consists of trousers and a portable water pump. Hot water is circulated through the trousers, evenly heating the buttocks, thighs and calf. We propose to conduct a pilot randomized, sham-controlled trial in 20 sedentary, old individuals to establish the effect of daily home-based leg HT for 12 weeks on skeletal muscle size and function, walking performance and perceived quality of life. Participants will be asked to apply the treatment daily for 90 min using water-circulating trousers perfused with water heated to 42ºC (HT group, n=10) or 33ºC (sham group, n=10). The primary study outcomes is the change from baseline in 6-minute walk distance at 12-week follow up. Secondary outcomes include changes in calf muscle strength, as assessed using isokinetic dynamometry , sit-to-stand time, and calf muscle cross-sectional area, fat content and bioenergetics.

Aging and a sedentary lifestyle are associated with a progressive deterioration of skeletal muscle contractile function and cardiorespiratory fitness, resulting in an impaired capacity to perform daily activities and maintain independent functioning. Few therapeutic options exist to combat the skeletal muscle abnormalities and restore muscle strength in older individuals. Heat therapy (HT) is a practical, non-invasive therapeutic tool that has been shown to elicit beneficial adaptations in both vasculature and skeletal muscle. Our objective is to conduct a pilot randomized, sham-controlled trial in 20 sedentary elderly individuals to establish the effect of home-based leg HT for 12 weeks on walking performance, calf muscle structure, function and metabolism, and on perceived quality of life. Individuals randomized to the leg HT group (n=10) will be asked to apply the treatment daily for 90 min using water-circulating trousers perfused with water heated to 42ºC. In the sham group (n=10), water at 33ºC will be circulated through the trousers. The primary study outcome is the change from baseline 6-minute walk distance at the 12-week follow up. Secondary outcomes include changes in calf muscle cross-sectional area, fat content and bioenergetics, as assessed using magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), peak torque of the plantar flexor muscles, as assessed using isokinetic dynamometry, sit-to-stand time, and perceived quality of life. Our working hypotheses are that elderly individuals receiving HT will manifest: 1) improved walking tolerance, 2) greater calf muscle cross-sectional area and volume, 3) enhanced strength of the plantar flexor muscles , 4) lower intramuscular fat content, 5) improved sit-to-stand muscle power, and 6) improved perceived quality of life. Our rationale for this research is that the results obtained can be expected to provide a strong evidence-based framework for the pursuit of a larger randomized clinical trial.

Participants will be provided a leg heat therapy system and will be instructed to apply the therapy daily (90 min/day) for 12 consecutive weeks. The water heater will circulate water at 33ºC.

Participants will be provided a leg heat therapy system and will be instructed to apply the therapy daily (90 min/day) for 12 consecutive weeks. The water heater will circulate water at 42ºC.

The leg heat therapy device consists of a water tank coupled with a circulator, a sous-vide water heater and water-circulating trousers. The water heater in the sham device is adjusted to heat up the water to 33ºC.

The leg heat therapy device consists of a water tank coupled with a circulator, a sous-vide water heater and water-circulating trousers. The water heater in the sham device is adjusted to heat up the water to 42ºC.

The investigators will determine whether home-based leg heat therapy improves the 6-minute walk distance at 12-week follow-up compared to the sham treatment.

The investigators will determine whether home-based leg heat therapy improves the peak torque of the triceps surae at 12-week follow-up compared to the sham treatment.

The investigators will determine whether home-based leg heat therapy improves the time to complete 5 chair rises at 12-week follow-up compared to the sham treatment.

The investigators will determine whether home-based leg heat therapy improves the score in the Walking Impairment Questionnaire at 12-week follow-up compared to the sham treatment.

The investigators will determine whether home-based leg heat therapy improves the score in the Short-Form (SF)-36 Questionnaire at 12-week follow-up compared to the sham treatment.

The investigators will determine whether home-based leg heat therapy enhances the volume and cross-sectional area of the triceps sure at 12-week follow-up compared to the sham treatment.

The investigators will determine whether home-based leg heat therapy reduces the fat content of the triceps sure at 12-week follow-up compared to the sham treatment.

The investigators will determine whether home-based leg heat therapy reduces the phosphocreatine recovery time constant at 12-week follow-up compared to the sham treatment.

Participants must be: 65 yrs or older Sedentary - Exercise less than three days/week, 20 minutes per day. Non smokers The exclusion criteria are: 1) smoking, 2) use of walking aid other than a cane, 3) active cancer, 4) unable to fit into water-circulating trousers, 5) unable to complete the 6-min walk test and 6) age under 65 yrs.