This intervention consists of a supervised, low-dose isometric handgrip exercise program delivered over 4 weeks using the Squegg handgrip device. Participants will complete two sessions per week, each consisting of 4x2-minute isometric handgrip contractions performed at 30% of maximal voluntary contraction, with 1-minute rest periods between contractions. Contractions will be performed using alternating hands. All sessions will be conducted in person and supervised by trained research staff at the Physical Activity Centre of Excellence, and the intervention will completed before participants' existing exercise routines. Ratings of perceived exertion will be recorded following each contraction.

High attendance rate will be defined as attending ≥75% of prescribed intervention sessions. This outcome will be calculated as the proportion of participants who meet or exceed this threshold, expressed as a percentage (%).

Retention will be assessed as the proportion of enrolled participants who complete the post-intervention assessment. Retention rate will be calculated as the number of participants who complete follow-up testing divided by the number enrolled, multiplied by 100 to yield a percentage (%).

Protocol fidelity will be assessed as the proportion of attended sessions in which participants complete the full isometric handgrip exercise protocol as prescribed (i.e., all contractions at the target intensity and duration). Fidelity will be calculated as the number of sessions completed according to protocol divided by the number of attended sessions, multiplied by 100 to yield a percentage (%). Higher values indicate greater fidelity.

Safety will be assessed by recording the number and type of adverse events occurring during or immediately following baseline testing, intervention sessions, or post-intervention testing. The total number of adverse events will be reported as a count.

Participants' perceptions of safety and comfort during the intervention will be explored through semi-structured, one-on-one interviews conducted following post-intervention testing. Responses will be analyzed qualitatively using thematic analysis.

Reasons for withdrawal will be recorded for all participants who discontinue participation prior to completing the study. Reasons will be documented based on participant report at the time of withdrawal. Reported reasons will be reviewed and grouped into categories as appropriate during analysis. The number of withdrawals in each category will be reported as a count (number of participants), and the distribution of reasons may also be summarized descriptively.

Feasibility of administering the cognitive and physiological assessment battery will be evaluated based on participant perceptions of the testing sessions, explored through semi-structured post-intervention interviews.

Participants are asked to alternate between numbers and letters in sequence (e.g., 1-A-2-B, etc.) while connecting circles as quickly as possible. This test assesses executive function and cognitive flexibility. Performance is measured as the total time in seconds (s) required to complete the task. Lower completion time indicates better performance.

The Montreal Cognitive Assessment (MoCA) is a brief screening tool used to assess global cognitive function across multiple domains, including memory, attention, language, and executive function. It consists of a series of tasks, with scores ranging from 0 to 30, where higher scores indicate better cognitive function.

Participants are given a key pairing numbers with symbols and are asked to match as many symbols to the corresponding numbers as possible within a fixed time period. This test assesses processing speed. Performance is measured as the number of correct responses completed within the time limit, reported as a count (number of correct responses), with higher scores indicating greater performance.

The Short Self-Regulation Questionnaire is a self-report measure that assesses an individual's ability to regulate their thoughts, emotions, and behaviors. Participants respond to a series of statements using a 5-point Likert scale, and responses are summed to generate a total score. Scores range from 31-155, with higher scores indicating greater self-regulation.

Interference score will be calculated using the paper-and-pencil Stroop Color and Word Test (Golden version). The interference score will be calculated using the Golden method, where predicted Color-Word performance is derived as (W × C) / (W + C), and interference is calculated as the difference between actual and predicted Color-Word scores (CW - [(W × C) / (W + C)]). Higher scores indicate better inhibitory control.

Number of correct responses in the Stroop Word condition completed within 45 seconds using the paper-and-pencil Stroop Color and Word Test (Golden version). Higher scores indicate better performance.

Number of correct responses in the Stroop Color condition completed within 45 seconds using the paper-and-pencil Stroop Color and Word Test (Golden version). Higher scores indicate better performance.

Number of correct responses in the Stroop Color-Word condition completed within 45 seconds using the paper-and-pencil Stroop Color and Word Test (Golden version). Higher scores indicate better performance.

The Rey Auditory Verbal Learning Test is used to assess verbal learning and memory. Participants are read a list of 15 words over five learning trials and asked to recall as many words as possible after each trial. Total acquisition score is calculated as the total number of correctly recalled words across the five learning trials, with higher scores indicating better verbal learning performance.

The Rey Auditory Verbal Learning Test is used to assess verbal learning and memory. Participants are read a list of 15 words over 5 learning trials and asked to recall as many words as possible after each trial. Learning score reflects improvement in recall performance across learning trials, with higher scores indicating greater learning efficiency.

The Rey Auditory Verbal Learning Test is used to assess verbal learning and memory. Following repeated learning trials of an initial word list, participants are presented with an interference list (List B). Proactive interference score is calculated as Trial 1 recall minus List B recall and reflects the extent to which previously learned information interferes with learning new information. Higher scores indicate greater proactive interference.

The Rey Auditory Verbal Learning Test is used to assess verbal learning and memory. After presentation of an interference list (List B), participants are asked to recall words from the original list. Retroactive interference score is calculated as Trial 5 recall minus Trial 6 recall and reflects the extent to which new information interferes with recall of previously learned information. Higher scores indicate greater retroactive interference.

The Rey Auditory Verbal Learning Test is used to assess verbal learning and memory. Following delayed recall, participants complete a recognition trial in which they identify previously presented words from a list of target and distractor words. Performance is measured as the number of correctly recognized target words, with higher scores indicating better recognition memory.

The Rey Auditory Verbal Learning Test is used to assess verbal learning and memory. Intrusion errors are defined as recalled words that were not included in the target word list during recall trials. Performance is measured as the total number of intrusion errors, with lower scores indicating better performance.

Resting systolic blood pressure will be measured using an automated device on the right arm following a 5-minute seated rest period. After the initial measurement, a second and third measurement will be taken, each separated by a 1-minute rest interval. Blood pressure will be recorded in millimeters of mercury (mmHg), with higher values indicating higher systolic blood pressure.

Resting diastolic blood pressure will be measured using an automated device on the right arm following a 5-minute seated rest period. After the initial measurement, a second and third measurement will be taken, each separated by a 1-minute rest interval. Blood pressure will be recorded in millimeters of mercury (mmHg), with higher values indicating higher diastolic blood pressure.

Resting heart rate will be measured using an automated device on the right arm following a 5-minute seated rest period. After the initial measurement, a second and third measurement will be taken, each separated by a 1-minute rest interval. Heart rate will be recorded in beats per minute (bpm), with lower values generally indicating better cardiovascular function.

Participant expectancy of cognitive improvement will be assessed at baseline using a single-item 6-item Likert-type scale adapted from prior research, with the response options ranging from "a little improvement" to "extreme improvement." Higher scores indicate greater expectancy of improvement. This measure will be used to explore associations between expectancy and changes in cognitive function.

Perceived exertion will be assessed immediately following each isometric handgrip contraction during each exercise session using the Borg 6-20 Rating of Perceived Exertion Scale. The scale ranges from 6 to 20, with higher scores indicating greater perceived exertion.