EX participants completed a 12-week exercise intervention (3-days/week, 45–60 min/session). The CON maintained their normal routine for the same duration. Participants of both groups were assessed for frailty status, functional task performance, and muscle strength at week 0 (pre-intervention) and 13 (post-intervention), and the latter two measures were repeated at weeks 5 and 9 for the EX (Figure 1).
Participants were recruited from the community. Inclusion criteria consisted of: 1) Females ≥ 65 years of age; 2) A Montreal Cognitive Assessment (21) score ≥ adjusted normative values (22); 3) No contraindications to exercise, as determined by the Physical Activity Readiness–Questionnaire Plus; 4) No major injuries/surgeries to the dominant arm or leg in the last six months; 5) Fluent in English; and 6) A pre-frail frailty status.
Initial recruitment found 53 older adults interested but only 21 agreed to complete the pre-intervention assessment, with one being excluded. As a quasi-experimental study, participants were randomized to the EX and CON based upon their perceived availability to participate in exercise. Current interventions utilizing exercise require 80% adherence (23). As a result, 9/20 participants were placed in the EX.
All participants read and signed a letter of informed consent. Ethical approval was granted by the institutional Research Ethics Board (H16-00712). All experimental procedures involved in the study conformed to the declaration of Helsinki.
Multi-Component Exercise (MCE)
Kinesiology students led each session. Details of the aerobic warm-up, as well as the balance exercises and flexibility cool-down are within Figure 1. Resistance training was divided into three blocks of four weeks; each new block decreased the number of repetitions to be completed and subsequently increased the resistance, thus, transitioning from training muscular endurance to strength. Within each block, the resistance was also increased when participants reached the upper limit of the repetition range for all sets. Rest periods between sets ranged from 1-3 minutes. To aid progressive overload, participants disclosed their rating of perceived exertion after the last set of every exercise. Details about the training principles can be found in our companion article, “Practical Implications for Strength and Conditioning of Older Pre-Frail Females” (24).
Four free-weight resistance exercises were selected: 1) Squat; 2) Deadlift; 3) Bench Press; and 4) Leg Press. Exercises 1-3 replicate functional movements, such as standing from a toilet, opening a door, and picking up groceries from the ground; these exercises utilized dumbbells (Hex Dumbbell, Northern Lights Inc, Cornwall, ON) and/or barbells (The Bella 2.0 — Females’s Bar, Rogue Fitness; Columbus, OH) with weighted plates (Virgin Rubber Grip Olympic Plates, Element Fitness; Latvia). The fourth exercise supplemented the Squat exercise but was less technically demanding, and utilized an incline leg press machine (TuffStuff PPL-960 45°Leg Press, TuffStuff Fitness Equipment, Chino, CA). Each session started with the squat or bench press and finished with the deadlift or inclined leg press.
Feasibility and Safety: Participant dropout and adverse events were recorded in an ongoing electrical document log. Adherence rates were maintained in an ongoing paper log that participants were required to sign upon arrival to each intervention session.
Frailty Status: Participants were included in this study if they were classified as pre-frail according to guidelines in at least one of the following three tools:
1-2 on the frailty phenotype (FP) (25)
4-6 on the clinical frailty scale (CFS) (26)
Gait speed (GS) of ≥ 1.0 – < 1.5 m/sec indicated pre-frailty (27)
Previous research suggests that several frailty tools may provide a more reliable measure of frailty status, and that the FP and CFS do not always provide the same classification (9,28). Therefore, GS was used as a third frailty criterion.
Functional Task Performance: GS was assessed across 8 meters (m), excluding acceleration (2m) and deceleration (2m) zones, at a self-selected walking speed that was considered normal. The GS test was completed twice and the fastest trial was used for data analysis. Handgrip strength was measured while standing with a dynamometer (Baseline Smedley, Fabrication Enterprises Incorporated, White Plains, NY) held at arm’s length and slightly abducted. The dynamometer was squeezed as hard as possible for three seconds, and completed twice for each hand. The order of grip testing was randomized and trials occurred between gait tests. The highest score was used for both functional task performance and FP. The sitto-stand (STS) task was adopted from the short physical performance battery (29).
Muscle Strength Performance: The Biodex Dynamometer System 4 Pro (Biodex Medical Systems Incorporated, Shirley, NY) was used to assess peak torque/velocity of isometric/isotonic knee extension (KE) and elbow flexion (EF). For KE and EF, participants were seated with their hips flexed to ~100°. Restraining straps crossed the chest and opposite hip, and for KE, a third was secured across the thigh of the tested leg. For KE, the lateral femoral condyle of the dominant leg was aligned with the dynamometer center of rotation. To account for the effect of gravity, the weight of the limb was calculated by the Biodex with the knee extended to 160°. For EF, the medial epicondyle of the elbow was aligned with the dynamometer center of rotation. The shoulder was slightly forward flexed (10-15°) and abducted. Positioning was measured, recorded, and replicated for all sessions.
Isometric KE and EF contractions were executed at a joint angle of 90°. Isotonic KE was also initiated from 90° but EF isotonic contractions were initiated from 160°. Range of motion of isotonic contractions was 90-160° for KE and the inverse for EF. Isotonic resistance was 20% of the peak torque from the strongest isometric contraction of the pre-intervention assessment. Participants completed five isometric and isotonic contractions for both KE and EF, with two minutes of rest between contractions. All contractions were recorded and the highest value was used for data analysis. The analogue signal was sampled at 2,000 Hz and stored for offline analysis using the Biodex software.
Pre-intervention characteristics were compared using an independent sample t-test. A sample size calculation for a 2-tailed study design advised a minimum sample size of six subjects per group to attain a statistical power of 0.80 for the KE strength variable. A two-way mixed ANOVA of time by group assessed all outcomes. A one-way ANOVA was used to evaluate any significant interactions and main effects. The EX was also examined over time using a one-way repeated measures ANOVA, with a Bonferroni post-hoc test. Sphericity was assessed (Mauchly’s) and a Greenhouse-Geisser correction applied if violated (p < 0.05). Data that violated normality and homogeneity of variances was transformed using the function Log10. Statistical significance was p ≤ 0.05. All values are reported as mean ± standard deviation (SPSS Statistics V.24, IBM Canada Ltd. Markham, Ontario).