Frailty is term widely used to denote a multidimensional syndrome associated with the loss of physical and cognitive reserve capacity that makes an individual vulnerable to cumulative clinical health conditions. The level of frailty can be classified as one of three phenotypes (non-frail; pre-frail, frail) using the Cardiac Health Study frailty index (CHS). The CHS assesses the number of physical deficits expressed by an individual. These deficits include (unexplained weight loss, poor grip strength, feelings of exhaustion, slowed gait, and low levels of physical activity). An individual who exhibits 1-2 deficits in physical function suggests a pre-frail phenotype. The Canadian Study of Health and Aging's Clinical Frailty Scale (CFS) classifies older adult's level of frailty using a 9-level scale, ranging from "Very fit" (level 1) to "Terminally ill" (level 9). An individual is considered vulnerable or mildly frail if they fall between levels 4 and 5 on the CFS. Both assessment tools will be used to assess frailty status. It becomes more difficult to restore physical health once the individual attains 3+ deficits on the CHS or ≥ level 6 on the CFS.

The purpose of this study is to determine if the pre-frail phenotype can be reversed in participants who are pre-frail and/or vulnerable or mildly frail using CHS and CFS assessment tools respectively. Both assessment tools are used as inclusion criteria and as outcome measures within this study. To confirm frailty status, gait speed will be evaluated over a 4-meter level walkway with an addition 2-meters on either end, to allow for acceleration and deceleration of walking speed. A normal gait speed of 1-1.5 meters/second is associated with persons expressing the pre-frailty phenotype. Females are most susceptible to frailty; therefore, this investigation targets females 65 years of age and older. Eligibility criteria includes only females (65+ years) who are considered pre-frail by the CHS and vulnerable to mildly frail (levels 4-5) on the CFS, with a normal gait speed between 1-1.5 meters/second. Individuals who are considered pre-frail are highlighted for our study as we believe that this demographic is at a critical-point of physical transition between frailty phenotypes. If pre-frail individuals do not actively engage in restorative exercise to reclaim muscle strength and balance, they will remain as pre-frail or continue to regress toward the frailty phenotype.

Frailty is a multidimensional geriatric syndrome additional assessment tools will be used to determine physical strengths and deficits within each individual. Participants will be cleared for exercise participation using the Physical Activity Readiness Questionnaire - Plus (PAR-Q+) and cleared for exercise by a Certified Exercise Physiologist (CEP). The CEP in good standing with the Canadian Society for Exercise Physiology and is trained to effectively screen participants with multiple co-morbidities for exercise and prescribe appropriate exercise programs for these participants. Participants with unstable health conditions will be advised to seek physician approval before re-entering the study using the PAR-Medx assessment form. Cognitive function will be assessed using the Montreal Cognitive Assessment (MoCA) tool to ensure that participants are not suffering from non-observable cognitive impairment.

Participants will be randomized, using a table of random numbers, to either an Exercise (EX) or a Control (CON) group. The EX group will participate in a 16-week multi-component training intervention (3x per week, 45 to 60 minutes/session, at moderate to vigorous intensity) that will include primarily resistance exercises, an aerobic warm-up and cool down, and include both flexibility and balance exercises throughout the session (Bray et al., 2016). The CON group will be asked to maintain their normal daily living habits for the same duration (16 weeks). At the conclusion of the 16-weeks the exercise program will be made available to the CON group participants.

The sample size goal of 50 participants, 25 per group (EX=25, CON=25) was determined based-upon previous research with this population. T-tests will be used to analyze intergroup differences at baseline and post intervention. Analysis of Variance (ANOVA) will be used to analyze intragroup differences at week 0 (baseline), week 8 (mid-point) and week 17 (post intervention). Measures of intragroup differences include frailty assessment measures (CHS and CFS), the Short Physical Performance Battery (SPPB) protocol, isotonic muscle strength of the dominate arm and leg using a Biodex System 4Pro Dynamometer will be assessed and daily physical activity accumulation will be examined using the Phone FITT questionnaire.

The investigators hypothesize that those who are randomly enrolled into the exercise intervention will reverse their frailty phenotype on the CHS index (i.e. 'pre-frail' become 'non-frail') and restore physical function to lower levels (\<4) on the CFS (i.e. 'vulnerable' become 'managing well'), while those in the control group will be unchanged or further regress in their frailty phenotype and become frail, or move further along the CFS toward greater levels of frailty. This research will provide support for the use of multi-component exercise as a proactive approach to restoring physical independence and quality of life for older adults.