A Randomized Factorial Feasibility Study of High-Resistance Circuit Training and Strength Training Intervention in Untrained Adolescents: A Mixed Methods Approach

Recruitment process

时间窗: Three weeks.

The recruitment process refers to the protocols used to find, select, and enroll participants into a study. The recruitment process for this study was represented by reporting the total number of unique QR code scans from posted flyers and tabling events, the number of completed interest forms, the number of eligible participants and the number of consented participants. A recruitment period of 3 weeks was given for the before and after-school trials.

Sample Size

时间窗: From enrollment through 4 weeks of treatment.

Sample size was used as another key feasibility marker and refers to the total number of individuals used in the intervention.

Consent Rate

时间窗: From a 3 week recruitment period to enrollment.

Consent rate is often referred to as the percentage of participants enrolled divided by the number of eligible participants. For this study, consent rate was calculated by taking the total number of participants that consented and were randomized divided by the number of eligible students.

Retention Rate

时间窗: From enrollment through 4 weeks of treatment.

Retention rate is defined as the percentage of the total number of randomized participants assessed for primary outcomes and used in the primary outcome analysis. For the purpose of this study, researchers were interested in retention for both primary and secondary outcomes meaning researchers tracked retention from pre-intervention fitness testing, through treatments, and post-intervention fitness testing sessions. The follow up interview was not included in calculating the retention rate. Only participants that withdrew from the study or were not included in the primary and secondary outcome analysis influenced the retention rate. Thus, retention was calculated as the percentage of participants that completed pre and post-intervention fitness assessments and intervention treatment divided by the number of participants randomized into treatment groups.

Fidelity

时间窗: From enrollment through 4 weeks of treatment.

For this study, fidelity was assessed at the instructor and participant level. Instructor fidelity was measured as a percentage by totaling the provided sessions divided by the total number of planned sessions. An acceptable percentage was set at 80% due to conflicts with events such as holiday breaks or parent teacher conferences. To assess participant fidelity, the primary researcher and participants recorded session durations, completed sets and intensity along with activity and diet audits at weeks 2, and 4 of the intervention. The activity and diet audit included a modified Copper Institute Fitnessgram and Activitygram questionnaire.

Average Attendance

时间窗: From enrollment through 4 weeks of treatment.

Participant attendance was observed by the researcher and measured as attended sessions divided by total sessions offered.

Adverse Events

时间窗: From enrollment through 4 weeks of treatment.

Adverse events were recorded during the intervention by the participants on workout documents and by observations from the primary researcher.

Participant Experience

时间窗: From enrollment through 4 weeks of treatment in addition to a 1 month follow up interview.

Participant experience was assessed by utilizing the validated short form 4 item Physical Activity Enjoyment Scale (PACES-S) survey for adolescents \[48\]. Participants answered 4 items including: "I enjoyed it; I find it pleasurable; It is very pleasant; and It feels good" by responding with the five-point Likert scale ranging from 1= "strongly disagree" to 5 = "strongly agree". To further investigators' depth of understanding, participant experience was also assessed by a follow up interview concluding the intervention.