High Intensity Interval Training (HIIT) to Reduce Frailty and Enhance Resilience in Older Veterans

Frailty is defined as a greater susceptibility to stressors resulting from age-related impairments in adaptive biological systems. Frailty leads to poorer physical performance and functional capacity and higher risk of adverse outcomes including falls, hospitalization, and mortality. Resilience, defined as the capacity to recover from disruptions to homeostasis, is critical to successful aging because it precedes frailty and enhances adults' ability to maintain optimal health and function well into older age. Evidence- based therapies to help older adults enhance resilience are limited and the biological underpinnings contributing to improved resilience have not yet been fully characterized. To address this important need, the investigators will conduct a clinical trial to examine the benefits of center- and home-based high intensity interval training (HIIT) on functional capacity, frailty, and resilience, and also to identify novel biomarkers of resilience in older Veterans.

Impact of Home-Based High Intensity Interval Training on Resilience in Older Veterans More than 30% of U.S. Veterans 65 years or older are frail, which is three-times higher than in non-Veterans in the same age group. Frailty is defined as an increased susceptibility to stressors resulting from age-related impairments in adaptive biological systems, leading to higher risk of adverse outcomes including falls, disability, hospitalization, and mortality. Further, frailty prevalence increases with age, affecting 50% of all adults 85 and over. Resilience, which is defined as the capacity to recover from stress-induced disruptions to homeostasis, is critical to successful aging because it precedes frailty and presents an opportunity to intervene on early health deficits, thus preventing aging-related decline in health, function, and quality of life. Evidence-based therapies that enhance resilience in older adults are limited and the complex biological and physiological mechanisms underlying resilience are not yet fully understood. Consequently, Veterans seeking to boost their ability to recover from late-life stressors and prevent frailty have few proven options. The investigators overarching aim is to characterize the complex factors contributing to resilience and develop novel strategies that enhance resilience to boost health span in older adults. Towards this end, the investigators previous VA RR\&D SPiRE Award allowed us to demonstrate the feasibility of 12-weeks of high intensity interval training (HIIT) among older Veterans. The investigators successfully enrolled and retained older male and female Veterans and safely conducted individually tailored HIIT that improved cardiorespiratory fitness, lower-body endurance, cognition, and quality of life. The purpose of the proposed larger trial is to build upon the investigators previous successes and develop and implement practical HIIT regimens to reduce frailty and enhance resilience in older Veterans. The investigators will conduct a randomized controlled trial to ascertain the therapeutic benefits of 12-weeks of center- and home-based HIIT on recovery and resilience among Veterans 60 years or older. The investigators have identified a series of biomarkers of resilience and are also seeking to examine key biological drivers of recovery at the molecular level. The investigators proposed study will not only identify feasible methods to measure resilience in older Veterans but will also assess the benefits of home-based HIIT on physical and cognitive performance, frailty, resilience, and health span.

Eligibility Criteria:
Inclusion Criteria:

* Ages 60 years
* Male and female, any race
* Medically cleared for exercise
* Non-frail or pre-frail (frailty score \< 3)

Exclusion Criteria:

* Severe co-morbidity: COPD (GOLD stage IV), CKD ( stage 3)), severe HTN (180 mmHg/120 mmHg)
* VA-SLUMS score 20 or lower (Cognition)