Effects of Microdosed Resistance Training During Physical Education on Health-Related Fitness in Adolescents
Effects of Microdosed Resistance Training During Physical Education Lessons on Health-Related Fitness in School Adolescents
This study will examine whether short bouts of resistance training incorporated into physical education lessons can improve health-related physical fitness in secondary school students aged 15-16 years.
A total of 264 students will participate in two successive cohorts. School classes, rather than individual students, will be randomly assigned to study groups. In the first cohort, three resistance-training programs using low, moderate, or high training loads will be compared with usual physical education. The program producing the most consistent beneficial changes will then be tested in a new group of students in the second cohort and compared with usual physical education.
Each training program will last eight weeks. Participants will be assessed before the intervention, halfway through it, immediately after it, and eight weeks after it ends. Assessments will include body composition, blood pressure, cardiorespiratory fitness, muscular fitness, jumping performance, trunk muscular endurance, and sprint performance.
The study will evaluate both average changes in each group and the proportion of students showing improvements greater than the expected measurement error of the tests.
Study Overview
Status
Conditions
Intervention / Treatment
Detailed Description
This school-based study is designed as a two-stage, cluster-randomized controlled trial consisting of an exploratory cohort followed by a confirmatory cohort. The school class is the unit of randomization. Planned enrollment is 132 students in each cohort, for a total of 264 participants.
In Cohort I, participating classes will be randomized in a 1:1:1:1 ratio to one of four study conditions: low-load resistance training, moderate-load resistance training, high-load resistance training, or usual physical education. The three resistance-training conditions will differ primarily in training load, repetition range, number of sets, rest intervals, and repetitions in reserve.
The resistance-training program showing the highest frequency of beneficial individual responses in Cohort I will be selected for further evaluation. A beneficial individual response will be defined as an improvement exceeding the minimal detectable change (MDC) for the respective outcome. Cohort II will include a new set of school classes randomized in a 1:1 ratio to either the resistance-training program selected from Cohort I or usual physical education.
Randomization will be performed at the class level using permuted blocks. Block size will be four classes in Cohort I and two classes in Cohort II. The sex composition of classes will be considered to support balanced allocation across study conditions. The randomization sequence will be generated using R with a fixed random seed. Participants and physical education teachers cannot be blinded to group assignment. Outcome assessors will remain unaware of class allocation where feasible.
The resistance-training interventions will be incorporated into regular physical education lessons and supervised by physical education teachers. Exercises will use body weight, dumbbells, medicine balls, and resistance bands. Training load will progress every two weeks by modifying repetitions, rest intervals, external resistance, or the number of sets according to the assigned training condition.
Measurements will be performed at four time points: before the intervention, at the intervention midpoint, immediately after the eight-week intervention, and eight weeks after completion of the intervention. Assessments will include anthropometric measures, body composition assessed by bioelectrical impedance analysis, resting blood pressure, cardiorespiratory fitness assessed using the 20-m shuttle run test, handgrip strength, countermovement jump performance, standing long jump performance, 30-second sit-up performance, and 10-m sprint performance. Somatic maturation, injury history, dietary habits, rating of perceived exertion, and repetitions in reserve will also be recorded.
Statistical analyses will account for repeated measurements and the clustering of students within school classes. Mixed-effects approaches, including linear mixed models and generalized linear mixed models where appropriate, will be used to evaluate changes over time and differences between study groups. Individual responsiveness will additionally be evaluated using outcome-specific MDC thresholds.
Study Type
Enrollment (Estimated)
Phase
- Not Applicable
Contacts and Locations
Study Contact
- Name: Dawid Koźlenia, PhD
- Phone Number: +48 71 347 33 61
- Email: dawid.kozlenia@awf.wroc.pl
Participation Criteria
Eligibility Criteria
Ages Eligible for Study
Accepts Healthy Volunteers
Genders Eligible for Study
Description
Inclusion Criteria:
- Enrollment in the second year of a participating secondary school.
- Participation in regular physical education lessons at the participating school.
- No health contraindications to physical exercise.
- Written informed consent from the participant and, for participants who are minors, written informed consent from a parent or legal guardian.
Exclusion Criteria:
- Acute or chronic musculoskeletal injury preventing safe participation in the exercise intervention or physical fitness assessments.
- Chronic disease or other medical condition constituting a contraindication to physical exercise.
- Medical recommendation limiting participation in physical activity.
- Acute infection or other temporary health condition preventing safe participation in a scheduled assessment.
- Lack of the required informed consent.
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Other
- Allocation: Randomized
- Interventional Model: Sequential Assignment
- Masking: Single
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
|---|---|
|
Experimental: Cohort I: Low-Load Resistance Training
Teacher-supervised resistance training incorporated into physical education lessons for eight weeks. Exercises use body weight, dumbbells, medicine balls, and resistance bands. The initial prescription consists of 2-3 sets of 12-15 repetitions, 30-40 seconds of rest between sets, and 3-4 repetitions in reserve. Training progresses every two weeks through planned changes in repetitions, rest intervals, external resistance, or number of sets. |
Teacher-supervised resistance training incorporated into physical education over eight weeks using body weight, dumbbells, medicine balls, and resistance bands. Cohort I compares three prescriptions: low-load (2-3 sets, 12-15 repetitions, 30-40 s rest, 3-4 repetitions in reserve), medium-load (3-4 sets, 8-12 repetitions, about 60 s rest, 2-3 repetitions in reserve), and high-load (4-5 sets, 6-8 repetitions, about 90 s rest, 1-2 repetitions in reserve). Progression occurs every two weeks through changes in repetitions, rest, external resistance, or sets. Cohort II receives the program selected from Cohort I based on the frequency of improvements exceeding minimal detectable change. |
|
Experimental: Cohort I: Moderate-Load Resistance Training
Teacher-supervised resistance training incorporated into physical education lessons for eight weeks. Exercises use body weight, dumbbells, medicine balls, and resistance bands. The initial prescription consists of 3-4 sets of 8-12 repetitions, approximately 60 seconds of rest between sets, and 2-3 repetitions in reserve. Training progresses every two weeks through planned changes in repetitions, rest intervals, external resistance, or number of sets. |
Teacher-supervised resistance training incorporated into physical education over eight weeks using body weight, dumbbells, medicine balls, and resistance bands. Cohort I compares three prescriptions: low-load (2-3 sets, 12-15 repetitions, 30-40 s rest, 3-4 repetitions in reserve), medium-load (3-4 sets, 8-12 repetitions, about 60 s rest, 2-3 repetitions in reserve), and high-load (4-5 sets, 6-8 repetitions, about 90 s rest, 1-2 repetitions in reserve). Progression occurs every two weeks through changes in repetitions, rest, external resistance, or sets. Cohort II receives the program selected from Cohort I based on the frequency of improvements exceeding minimal detectable change. |
|
Experimental: Cohort I: High-Load Resistance Training
Teacher-supervised resistance training incorporated into physical education lessons for eight weeks. Exercises use body weight, dumbbells, medicine balls, and resistance bands. The initial prescription consists of 4-5 sets of 6-8 repetitions, approximately 90 seconds of rest between sets, and 1-2 repetitions in reserve. Training progresses every two weeks through planned changes in repetitions, rest intervals, external resistance, or number of sets. |
Teacher-supervised resistance training incorporated into physical education over eight weeks using body weight, dumbbells, medicine balls, and resistance bands. Cohort I compares three prescriptions: low-load (2-3 sets, 12-15 repetitions, 30-40 s rest, 3-4 repetitions in reserve), medium-load (3-4 sets, 8-12 repetitions, about 60 s rest, 2-3 repetitions in reserve), and high-load (4-5 sets, 6-8 repetitions, about 90 s rest, 1-2 repetitions in reserve). Progression occurs every two weeks through changes in repetitions, rest, external resistance, or sets. Cohort II receives the program selected from Cohort I based on the frequency of improvements exceeding minimal detectable change. |
|
No Intervention: Cohort I: Usual Physical Education
Students assigned to the control arm will continue their usual school physical education lessons for eight weeks and will not receive the study-specific resistance training microdosing intervention. |
|
|
Experimental: Cohort II: Selected Resistance Training Program
Teacher-supervised resistance training incorporated into physical education lessons for eight weeks. The program will be the low-, moderate-, or high-load resistance training protocol selected after completion of Cohort I according to the prespecified criterion of the highest frequency of beneficial individual responses exceeding the minimal detectable change in the assessed health-related fitness outcomes. The selected protocol will be implemented in a new set of school classes in Cohort II |
Teacher-supervised resistance training incorporated into physical education over eight weeks using body weight, dumbbells, medicine balls, and resistance bands. Cohort I compares three prescriptions: low-load (2-3 sets, 12-15 repetitions, 30-40 s rest, 3-4 repetitions in reserve), medium-load (3-4 sets, 8-12 repetitions, about 60 s rest, 2-3 repetitions in reserve), and high-load (4-5 sets, 6-8 repetitions, about 90 s rest, 1-2 repetitions in reserve). Progression occurs every two weeks through changes in repetitions, rest, external resistance, or sets. Cohort II receives the program selected from Cohort I based on the frequency of improvements exceeding minimal detectable change. |
|
No Intervention: Cohort II: Usual Physical Education
New classes assigned to the control arm will continue their usual school physical education lessons for eight weeks and will not receive the study-specific resistance training microdosing intervention. |
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Change in Body Fat Percentage
Time Frame: Baseline, week 4, week 8, and week 16
|
Body fat percentage will be assessed using bioelectrical impedance analysis. Measurements will be obtained at baseline, week 4, week 8, and week 16. Change from baseline at each post-baseline assessment will be analyzed and expressed in percentage points. |
Baseline, week 4, week 8, and week 16
|
|
Change in Muscle Mass
Time Frame: Baseline, week 4, week 8, and week 16
|
Muscle mass will be assessed using bioelectrical impedance analysis. Measurements will be obtained at baseline, week 4, week 8, and week 16. Change from baseline at each post-baseline assessment will be analyzed. |
Baseline, week 4, week 8, and week 16
|
|
Change in Systolic Blood Pressure
Time Frame: Baseline, week 4, week 8, and week 16
|
Systolic blood pressure will be measured after five minutes of seated rest. Three measurements will be obtained at each assessment, and the mean of the three measurements will be used for analysis. Change from baseline at each post-baseline assessment will be analyzed. |
Baseline, week 4, week 8, and week 16
|
|
Change in Diastolic Blood Pressure
Time Frame: Baseline, week 4, week 8, and week 16
|
Diastolic blood pressure will be measured after five minutes of seated rest. Three measurements will be obtained at each assessment, and the mean of the three measurements will be used for analysis. Change from baseline at each post-baseline assessment will be analyzed. |
Baseline, week 4, week 8, and week 16
|
|
Change in Estimated Maximal Oxygen Uptake
Time Frame: Baseline, week 8
|
Cardiorespiratory fitness will be assessed using the 20-m shuttle run test. Maximal oxygen uptake (VO2max) will be estimated from test performance. Measurements will be obtained at baseline, week 4, week 8, and week 16, and change from baseline will be analyzed. |
Baseline, week 8
|
|
Change in Handgrip Strength
Time Frame: Baseline, week 4, week 8, and week 16
|
Isometric handgrip strength will be assessed using a handgrip dynamometer. Measurements will be obtained at baseline, week 4, week 8, and week 16. Change from baseline at each post-baseline assessment will be analyzed. |
Baseline, week 4, week 8, and week 16
|
|
Change in Countermovement Jump Performance
Time Frame: Baseline, week 4, week 8, and week 16
|
Vertical lower-limb power will be assessed using the countermovement jump. Jump height will be recorded at baseline, week 4, week 8, and week 16. Change from baseline at each post-baseline assessment will be analyzed. |
Baseline, week 4, week 8, and week 16
|
|
Change in Standing Long Jump Performance
Time Frame: Baseline, week 4, week 8, and week 16
|
Horizontal lower-limb power will be assessed using the standing long jump. Jump distance will be recorded at baseline, week 4, week 8, and week 16. Change from baseline at each post-baseline assessment will be analyzed. |
Baseline, week 4, week 8, and week 16
|
|
Change in 30-Second Sit-Up Performance
Time Frame: Baseline, week 4, week 8, and week 16
|
Trunk muscular endurance will be assessed using a 30-second sit-up test. The number of correctly completed repetitions will be recorded at baseline, week 4, week 8, and week 16. Change from baseline at each post-baseline assessment will be analyzed. |
Baseline, week 4, week 8, and week 16
|
|
Change in 10-m Sprint Performance
Time Frame: Baseline, week 4, week 8, and week 16
|
Locomotor speed and acceleration will be assessed using a 10-m sprint measured with photocells. Two trials will be performed, and the best performance will be used for analysis. Measurements will be obtained at baseline, week 4, week 8, and week 16, and change from baseline will be analyzed. |
Baseline, week 4, week 8, and week 16
|
Collaborators and Investigators
Collaborators
Investigators
- Principal Investigator: Dawid Koźlenia, PhD, Wroclaw University of Health and Sport Sciences
Study record dates
Study Major Dates
Study Start (Estimated)
Primary Completion (Estimated)
Study Completion (Estimated)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Actual)
Study Record Updates
Last Update Posted (Actual)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Keywords
Other Study ID Numbers
- NdRS/SP/0160/2025/01
- NdRS/SP/0160/2025/01 (Other Grant/Funding Number: inistry of Science and Higher Education, Poland)
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
IPD Plan Description
De-identified individual participant data underlying the results reported in study publications may be shared with qualified researchers upon reasonable request to the Principal Investigator, subject to applicable data protection regulations, institutional requirements, and the conditions of informed consent. No directly identifiable participant information will be shared.
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Studies a U.S. FDA-regulated device product
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