This randomized controlled trial evaluates the effects of adding blood flow restriction training to regular roller skating training on neuromuscular function under non-fatigued and fatigued conditions, muscle morphology, body composition, physiological responses, lower-limb strength, and roller skating performance in competitive roller skaters. Thirty participants aged 18 to 25 years will be randomly assigned to either a blood flow restriction training group or a regular training control group. Both groups will complete the same standardized 10-week roller skating training program. The blood flow restriction training group will wear pressure cuffs individualized according to each participant's arterial occlusion pressure during selected training sessions three times per week, while the control group will complete the same training without blood flow restriction. Before and after the intervention, participants will complete standardized assessments of muscle morphology using musculoskeletal ultrasound, body composition using dual-energy X-ray absorptiometry, and lower-limb strength using handheld dynamometry and one-repetition maximum tests. Physiological responses will be evaluated using blood lactate concentration and heart rate variability. Roller skating performance will be assessed using sprint, repeated-sprint, and endurance skating tests. Neuromuscular function, jump performance, and balance will also be assessed under both non-fatigued and fatigued conditions. Surface electromyography and force-platform data will be collected simultaneously during selected jump and single-leg balance tasks. The Y-Balance Test will be conducted separately without surface electromyography. The study aims to determine whether blood flow restriction training improves muscle and neuromuscular adaptations, body composition, strength, physiological responses, and roller skating performance, and whether it helps roller skaters maintain neuromuscular function, jump performance, and balance during fatigue.
This study is a randomized, parallel-group controlled trial designed to evaluate the effects of blood flow restriction training added to regular roller skating training in competitive roller skaters. Thirty participants aged 18 to 25 years will be recruited and randomly assigned to either a blood flow restriction training group or a regular training control group. Both groups will complete the same standardized roller skating training program for 10 weeks. Participants in the blood flow restriction training group will wear blood flow restriction cuffs during selected portions of regular training three times per week for approximately 20 to 30 minutes per session. Cuff pressure will be individualized according to each participant's arterial occlusion pressure. Participants in the control group will complete the same training content, frequency, and duration without blood flow restriction. Assessments will be conducted before and after the 10-week intervention using the same standardized procedures. Because the assessment battery includes multiple physiological, morphological, neuromuscular, and performance measures, baseline and post-intervention testing will each be completed over three separate sessions. The first assessment session will evaluate basic anthropometric characteristics, lower-limb muscle morphology, body composition, and strength. Musculoskeletal ultrasound will be used to assess prespecified lower-limb muscle morphology, including muscle thickness, muscle volume, and pennation angle. Dual-energy X-ray absorptiometry will be used to assess body composition and bone-related measures. Lower-limb strength will be assessed using handheld dynamometry, maximal voluntary contraction testing, and one-repetition maximum tests. The second assessment session will evaluate neuromuscular function, jump performance, and balance under both non-fatigued and fatigued conditions. Surface electromyography and force-platform data will be collected simultaneously during selected jump, landing, and single-leg balance tasks. The Y-Balance Test will be conducted separately without surface electromyography. After completion of the non-fatigued assessments, participants will undergo a cycle ergometer-based fatigue protocol followed by a standardized roller skating-specific fatigue protocol. Fatigue status will be determined using blood lactate concentration, heart rate, rating of perceived exertion, power output, and task performance. Once the predefined fatigue criteria are reached, participants will repeat the relevant neuromuscular, jump, and balance assessments. The third assessment session will evaluate roller skating-specific performance using short-distance sprint skating tests, repeated-sprint skating tests, and an endurance skating test. Physiological responses, including blood lactate concentration and heart rate variability, will also be assessed at prespecified time points. Training attendance, heart rate, rating of perceived exertion, internal training load, participant discomfort, and adverse events will be monitored throughout the intervention. The study will compare changes from baseline to post-intervention between the blood flow restriction training group and the control group and will also examine whether blood flow restriction training reduces fatigue-related declines in neuromuscular function, jump performance, and balance.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
30
Participants will complete a 10-week standardized roller skating training program. During regular roller skating training, participants will wear blood flow restriction cuffs three times per week for 20 minutes per session. Cuff pressure will be individualized according to each participant's arterial occlusion pressure and progressively increased according to a prespecified protocol: 40% of arterial occlusion pressure during weeks 1-2, 50% during weeks 3-4, and 60% during weeks 5-10. Progression to the next pressure stage will occur only if the participant tolerates the current pressure without excessive discomfort or abnormal responses. Training attendance, heart rate, rating of perceived exertion, pressure-related discomfort, and adverse events will be monitored throughout the intervention.
Participants will complete a 10-week standardized roller skating training program with the same training content, frequency, duration, and monitoring procedures as the experimental group, but without blood flow restriction. Training attendance, heart rate, rating of perceived exertion, discomfort, and adverse events will be monitored throughout the intervention.
Change From Baseline in Ultrasound-Derived Lower-Limb Muscle Morphology
A GE LOGIQ e portable ultrasound system will be used to assess the morphology of prespecified lower-limb muscles using standardized anatomical locations, participant positioning, transducer placement, and image-acquisition procedures. Outcomes will include muscle thickness measured in millimeters, pennation angle measured in degrees, and estimated muscle volume measured in cubic centimeters. Repeated measurements obtained during each assessment will be averaged for analysis. Changes from baseline to Week 10 will be compared between the blood flow restriction training group and the active control group.
Time frame: Baseline and Week 10 (post-intervention)
Mean Change From Baseline in Normalized Mean RMS Amplitude During Single-Leg Countermovement Jump Without Arm Swing
A Cometa wireless surface electromyography system (REF WP180R116PCC1) will record activity of the gluteus medius, biceps femoris, vastus medialis, vastus lateralis, medial gastrocnemius, and tibialis anterior during left- and right-leg single-leg countermovement jumps performed without arm swing. Mean root mean square amplitude will be calculated over the prespecified movement epoch and normalized to maximal voluntary contraction, expressed as a percentage of MVC. Valid trials will be averaged. Values will be reported separately by muscle, test limb, and fatigue condition; no cross-muscle or cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol
Mean Change From Baseline in Normalized Mean RMS Amplitude During Squat Jump With Hands on Hips
A Cometa wireless surface electromyography system (REF WP180R116PCC1) will record activity of the gluteus medius, biceps femoris, vastus medialis, vastus lateralis, medial gastrocnemius, and tibialis anterior during the squat jump performed with the hands maintained on the hips throughout the movement. Mean root mean square amplitude will be calculated over the prespecified movement epoch and normalized to maximal voluntary contraction, expressed as a percentage of MVC. Valid trials will be averaged. Values will be reported separately for each muscle and fatigue condition; no cross-muscle composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol
Mean Change From Baseline in Normalized Mean RMS Amplitude During Five Consecutive Countermovement Jumps
A Cometa wireless surface electromyography system (REF WP180R116PCC1) will record activity of the gluteus medius, biceps femoris, vastus medialis, vastus lateralis, medial gastrocnemius, and tibialis anterior during five consecutive countermovement jumps. Mean root mean square amplitude will be calculated separately for each jump over the prespecified movement epoch and normalized to maximal voluntary contraction, expressed as a percentage of MVC. The five repetition-specific values will be averaged. Values will be reported separately for each muscle and fatigue condition; no cross-muscle composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol
Mean Change From Baseline in Normalized Mean RMS Amplitude During Ten Consecutive Straight-Leg Jumps
A Cometa wireless surface electromyography system (REF WP180R116PCC1) will record activity of the gluteus medius, biceps femoris, vastus medialis, vastus lateralis, medial gastrocnemius, and tibialis anterior during ten consecutive straight-leg jumps. Mean root mean square amplitude will be calculated separately for each jump over the prespecified movement epoch and normalized to maximal voluntary contraction, expressed as a percentage of MVC. The ten repetition-specific values will be averaged. Values will be reported separately for each muscle and fatigue condition; no cross-muscle composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol
Mean Change From Baseline in Normalized Mean RMS Amplitude During Left- and Right-Leg Lateral Bound
A Cometa wireless surface electromyography system (REF WP180R116PCC1) will record activity of the gluteus medius, biceps femoris, vastus medialis, vastus lateralis, medial gastrocnemius, and tibialis anterior during left- and right-leg lateral bound tasks. Mean root mean square amplitude will be calculated over the prespecified movement epoch and normalized to maximal voluntary contraction, expressed as a percentage of MVC. Valid trials will be averaged. Values will be reported separately by muscle, test limb, and fatigue condition; no cross-muscle or cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in the Fatigue-Induced Change in Normalized Mean RMS Amplitude of the Gluteus Medius During Bilateral Countermovement Jump With Hands on Hips
A Cometa wireless surface electromyography system (REF WP180R116PCC1) will be used to record gluteus medius activity during the bilateral countermovement jump performed with the hands maintained on the hips before and immediately after the standardized fatigue-induction protocol at baseline and Week 10. Mean root mean square amplitude will be calculated over the prespecified movement epoch and normalized to the participant's maximal voluntary contraction, expressed as a percentage of MVC. Valid trials under each fatigue condition will be averaged to obtain one value for that condition. The fatigue-induced change will be calculated as the post-fatigue value minus the pre-fatigue value. The reported outcome will be calculated as the Week 10 fatigue-induced change minus the baseline fatigue-induced change.
Time frame: Baseline and Week 10 (post-intervention), with measurements obtained before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Medial Gastrocnemius Pennation Angle at 30% of Lower-Leg Length at Rest
A GE LOGIQ e portable ultrasound system will be used to assess medial gastrocnemius pennation angle at 30% of the distance from the midpoint of the popliteal crease to the medial malleolus, measured distally from the popliteal crease, while the participant is at rest using standardized participant positioning, transducer placement, and image-acquisition procedures. Pennation angle will be defined as the angle between a clearly visible muscle fascicle and the relevant aponeurosis according to the prespecified image-analysis protocol. Three valid images or measurements will be obtained at each assessment and averaged to produce one participant-level value. Change from baseline will be calculated as the Week 10 mean value minus the baseline mean value.
Time frame: Baseline and Week 10 (post-intervention)
Mean Change From Baseline in Average Pennation Angle Across Seven Prespecified Lower-Limb Ultrasound Site-Condition Combinations
A GE LOGIQ e portable ultrasound system will assess pennation angle (degrees) at seven prespecified site-condition combinations: medial gastrocnemius at 30% lower-leg length at rest and during 50% MVC isometric plantar flexion; vastus lateralis at 30%, 50%, and 70% thigh length at rest; and rectus femoris at 50% thigh length at rest and during 50% MVC isometric knee extension. Lower-leg length is the distance from the midpoint of the popliteal crease to the medial malleolus. Thigh length is measured from the greater trochanter to the lateral femoral epicondyle for the vastus lateralis and from the anterior superior iliac spine to the superior patellar border for the rectus femoris. Repeated measurements will be averaged within each combination and then across all seven combinations. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Mean Change From Baseline in Average Muscle Thickness Across Seven Prespecified Lower-Limb Ultrasound Site-Condition Combinations
A GE LOGIQ e portable ultrasound system will assess muscle thickness (millimeters) at seven prespecified site-condition combinations: medial gastrocnemius at 30% lower-leg length at rest and during 50% MVC isometric plantar flexion; vastus lateralis at 30%, 50%, and 70% thigh length at rest; and rectus femoris at 50% thigh length at rest and during 50% MVC isometric knee extension. Lower-leg length is the distance from the midpoint of the popliteal crease to the medial malleolus. Thigh length is measured from the greater trochanter to the lateral femoral epicondyle for the vastus lateralis and from the anterior superior iliac spine to the superior patellar border for the rectus femoris. Repeated measurements will be averaged within each combination and then across all seven combinations. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Mean Change From Baseline in Average Fascicle Length Across Seven Prespecified Lower-Limb Ultrasound Site-Condition Combinations
A GE LOGIQ e portable ultrasound system will assess muscle fascicle length (millimeters) at seven prespecified site-condition combinations: medial gastrocnemius at 30% lower-leg length at rest and during 50% MVC isometric plantar flexion; vastus lateralis at 30%, 50%, and 70% thigh length at rest; and rectus femoris at 50% thigh length at rest and during 50% MVC isometric knee extension. Lower-leg length is the distance from the midpoint of the popliteal crease to the medial malleolus. Thigh length is measured from the greater trochanter to the lateral femoral epicondyle for the vastus lateralis and from the anterior superior iliac spine to the superior patellar border for the rectus femoris. Repeated measurements will be averaged within each combination and then across all seven combinations. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Mean Change From Baseline in Velocity-Derived Jump Height Across Prespecified Jump Tasks
A force platform will assess vertical ground reaction force during bilateral CMJ and SJ with hands on hips, five consecutive CMJs and ten straight-leg jumps with hands on hips, left- and right-leg single-leg CMJs without hands on hips, and left- and right-leg lateral bounds without hands on hips. Jump height will be calculated from take-off velocity derived from the vertical force-time curve. Valid trials will be averaged within each task and fatigue condition; repeated-jump values will be averaged across repetitions. Results will be reported separately by task, limb, and fatigue condition. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Jump-Height Decrement During Repeated Jump Tasks
A force-platform system will be used to assess jump-height decrement during five consecutive countermovement jumps with hands on hips and ten consecutive straight-leg jumps with hands on hips. Jump height will first be calculated for each repetition from take-off velocity. Jump-height decrement will be calculated for each complete repeated-jump series using the prespecified force-platform analysis formula. One decrement value will be obtained for each repeated-jump task and fatigue condition. Results will be reported in prespecified task and fatigue-condition categories; no cross-task composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each category.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Maximum Relative Force Across Prespecified Jump Tasks
A force platform will record vertical ground reaction force during bilateral CMJ and SJ with hands on hips, five consecutive CMJs and ten straight-leg jumps with hands on hips, left- and right-leg single-leg CMJs without hands on hips, and left- and right-leg lateral bounds without hands on hips. Maximum relative force will be defined as peak vertical ground reaction force divided by body weight. Valid trials will be averaged within each task and fatigue condition; repeated-jump values will be averaged across repetitions. Results will be reported separately by task, limb, and fatigue condition. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Relative Peak Vertical Power Across Prespecified Jump Tasks
A force platform will assess relative peak vertical power during bilateral countermovement and squat jumps, five consecutive countermovement jumps, ten consecutive straight-leg jumps, left- and right-leg single-leg countermovement jumps, and left- and right-leg lateral bounds. Instantaneous vertical power will be calculated as vertical ground reaction force multiplied by center-of-mass vertical velocity. Relative peak vertical power will be the highest instantaneous vertical power divided by body mass. Repetition-specific values from repeated-jump tasks will be averaged within each trial, and valid trials will then be averaged within each task and fatigue condition. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Modified Reactive Strength Index Across Prespecified Jump Tasks
A force platform will assess modified reactive strength index during bilateral CMJ and SJ with hands on hips, five consecutive CMJs and ten straight-leg jumps with hands on hips, left- and right-leg single-leg CMJs without hands on hips, and left- and right-leg lateral bounds without hands on hips. RSImod will be calculated as jump height divided by time to take-off. Valid trials will be averaged within each task and fatigue condition; repeated-jump values will be averaged across repetitions. Results will be reported separately by task, limb, and fatigue condition. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Concentric Impulse Across Prespecified Jump Tasks
A force platform will assess concentric impulse during bilateral CMJ and SJ with hands on hips, five consecutive CMJs and ten straight-leg jumps with hands on hips, left- and right-leg single-leg CMJs without hands on hips, and left- and right-leg lateral bounds without hands on hips. Concentric impulse will be calculated as the time integral of net vertical force during the concentric propulsion phase. Valid trials will be averaged within each task and fatigue condition; repeated-jump values will be averaged across repetitions. Results will be reported separately by task, limb, and fatigue condition. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Maximum Landing Force Across Prespecified Jump Tasks
A force platform will assess maximum landing force during bilateral CMJ and SJ with hands on hips, five consecutive CMJs and ten straight-leg jumps with hands on hips, left- and right-leg single-leg CMJs without hands on hips, and left- and right-leg lateral bounds without hands on hips. Maximum landing force will be defined as the highest vertical ground reaction force recorded after initial ground contact. Valid trials will be averaged within each task and fatigue condition; repeated-jump values will be averaged across repetitions. Results will be reported separately by task, limb, and fatigue condition. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Time to Stabilization Across Prespecified Landing Tasks
A force platform will assess time to stabilization (seconds) after landing during eight prespecified tasks: bilateral countermovement jump and squat jump with hands on hips; five consecutive countermovement jumps and ten consecutive straight-leg jumps with hands on hips; left- and right-leg single-leg countermovement jumps without hands on hips; and left- and right-leg lateral bounds without hands on hips. Time to stabilization will be defined as the interval from initial ground contact until the force signal meets the prespecified stability criterion for the required continuous duration. Valid trials will be averaged within each task and fatigue condition. For repeated-jump tasks, repetition-specific values will also be averaged. Results will be reported separately by task, limb and fatigue condition. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Total Center-of-Pressure Sway Path Length During Single-Leg Standing
A force-platform system will be used to record center-of-pressure displacement during separate left- and right-leg single-leg standing trials. Total center-of-pressure sway path length will be calculated as the cumulative distance traveled by the center of pressure during the valid trial. Repeated valid trials will be averaged separately for each limb and fatigue condition. Results will be reported in prespecified limb and fatigue-condition categories; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each category. Higher values indicate greater postural sway and poorer static stability.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Mean Center-of-Pressure Sway Velocity During Single-Leg Standing
A force-platform system will be used to record center-of-pressure displacement during separate left- and right-leg single-leg standing trials. Mean center-of-pressure sway velocity will be calculated as total center-of-pressure sway path length divided by valid trial duration. Repeated valid trials will be averaged separately for each limb and fatigue condition. Results will be reported in prespecified limb and fatigue-condition categories; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each category. Higher values indicate faster postural sway and poorer static stability.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Mean Change From Baseline in Center-of-Pressure Sway Envelope Area During Single-Leg Standing
A force-platform system will be used to record center-of-pressure displacement during separate left- and right-leg single-leg standing trials. Center-of-pressure sway envelope area will be calculated as the area enclosing the center-of-pressure trajectory during the valid trial using the prespecified force-platform software algorithm. Repeated valid trials will be averaged separately for each limb and fatigue condition. Results will be reported in prespecified limb and fatigue-condition categories; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each category. Higher values indicate a larger sway range and poorer static stability.
Time frame: Baseline and Week 10 (post-intervention), assessed before and immediately after the standardized fatigue-induction protocol at each assessment
Change From Baseline in Force-Platform-Derived Jump and Single-Leg Balance Outcomes Under Non-Fatigued and Fatigued Conditions
A KWYB-FP6050 three-dimensional force platform will be used to assess prespecified jump, landing, and single-leg balance tasks under non-fatigued and fatigued conditions. The tasks will include the countermovement jump, single-leg countermovement jump, squat jump, five consecutive squat jumps, 10 consecutive straight-leg jumps, lateral jumps, and single-leg balance. Outcomes will include center-of-pressure displacement and velocity, ground reaction force variables, and related kinetic and postural-control measures. Changes from baseline to Week 10 will be compared between the blood flow restriction training group and the active control group. Fatigue-related changes within each assessment and between-group differences in these changes will also be evaluated.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Dynamic Balance Assessed by the Y-Balance Test Under Non-Fatigued and Fatigued Conditions
A Y Balance Test Kit (Functional Movement Systems, Inc.) will be used to assess lower-limb dynamic balance under non-fatigued and fatigued conditions. Normalized reach distances in the anterior, posteromedial, and posterolateral directions, as well as the composite reach score, will be recorded for each lower limb. Changes from baseline to Week 10 will be compared between the blood flow restriction training group and the active control group. Fatigue-related changes within each assessment and between-group differences in these changes will also be evaluated.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Body Composition and Bone Mineral Density Assessed by Dual-Energy X-Ray Absorptiometry
A GE Lunar iDXA dual-energy X-ray absorptiometry system will be used to assess body composition and bone mineral density. Outcomes will include lean mass measured in kilograms, fat mass measured in kilograms, body fat percentage, and bone mineral density measured in grams per square centimeter. Changes from baseline to Week 10 will be compared between the blood flow restriction training group and the active control group.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Lower-Limb and Trunk Maximal Isometric Strength Assessed by Handheld Dynamometry
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
A microFET3 handheld dynamometer will be used to assess maximal isometric strength during prespecified lower-limb and trunk movements, including ankle dorsiflexion and plantar flexion, knee extension and flexion, hip flexion and extension, hip abduction and adduction, and trunk rotation. Testing will be conducted using standardized participant positions, joint angles, stabilization procedures, and verbal instructions. Force will be recorded in newtons. Repeated valid trials for each movement will be summarized according to the prespecified testing protocol. Changes from baseline to Week 10 will be compared between the blood flow restriction training group and the active control group.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Lower-Limb One-Repetition Maximum Strength
One-repetition maximum strength will be assessed using standardized testing procedures for the squat, leg press, leg extension, and hip abduction exercises. For each exercise, the maximum load successfully completed for one repetition with correct technique will be recorded in kilograms. Changes from baseline to Week 10 will be compared between groups.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Surface Electromyographic Activity During Maximal Voluntary Contractions
A Cometa wireless surface electromyography system (REF WP180R116PCC1) will be used to record muscle activity during standardized maximal voluntary contractions for five prespecified movements: hip abduction, knee extension, knee flexion, ankle dorsiflexion, and ankle plantar flexion. Standardized participant positioning, joint angles, stabilization procedures, electrode placement, and verbal instructions will be used for each movement. Surface electromyographic amplitude measures will be derived from repeated valid trials according to the prespecified signal-processing protocol. Changes from baseline to Week 10 will be compared between the blood flow restriction training group and the active control group.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Blood Lactate Response to Fatigue Induction
Capillary blood lactate concentration will be measured using a Lactate Scout Sport portable blood lactate analyzer. Earlobe blood samples will be collected at rest and following the standardized fatigue-induction protocol. Blood lactate concentration will be recorded in millimoles per liter. Changes in resting and post-fatigue blood lactate concentrations from baseline to Week 10 will be compared between the blood flow restriction training group and the active control group.
Time frame: Baseline and Week 10 (post-intervention), assessed before fatigue induction, immediately after fatigue induction, and 20 minutes after fatigue induction
Change From Baseline in Roller Skating-Specific Performance
Roller skating-specific performance will be assessed using 10-meter, 55-meter, and 110-meter sprint skating tests, a repeated-sprint skating test, and a 5-minute endurance skating test. Sprint and repeated-sprint performance will be assessed using completion-time measures recorded in seconds. Endurance performance will be assessed using the number of laps completed during the 5-minute test. Changes from baseline to Week 10 will be compared between groups.
Time frame: Baseline and Week 10 (post-intervention)
Incidence of Intervention-Related Adverse Events
Intervention-related adverse events will be monitored throughout the 10-week training period. Events of interest will include excessive pain, numbness, dizziness, chest discomfort, abnormal skin reactions, unusual fatigue, musculoskeletal discomfort, and any event requiring modification or discontinuation of blood flow restriction or training. The number and proportion of participants experiencing adverse events will be summarized for each group.
Time frame: Throughout the 10-week intervention
Change From Baseline in Heart Rate Variability Response and Recovery Following Exercise
Heart rate and R-R interval data will be recorded using a Polar H10 heart rate monitoring system and analyzed using Kubios HRV software. Heart rate variability will be assessed at three prespecified time points during each testing session: before the 30-second Wingate test, immediately after the test, and 20 minutes after the test. Prespecified time-domain and frequency-domain indices will be derived from the recorded R-R intervals using standardized artifact-correction and analysis procedures. The pre-exercise values will characterize resting autonomic regulation, the immediate post-exercise values will characterize the acute autonomic response to exercise, and the 20-minute post-exercise values will characterize autonomic recovery. Changes from baseline to Week 10 will be compared between the blood flow restriction training group and the active control group.
Time frame: Baseline and Week 10 (post-intervention), assessed before exercise, immediately after exercise, and 20 minutes after exercise
Change From Baseline in Fatigue-Induced Change in Bilateral Mean Normalized Anterior Reach Distance
A Y Balance Test Kit (Functional Movement Systems, Inc.) will assess anterior reach for both lower limbs under non-fatigued and fatigued conditions at baseline and Week 10. The best valid reach for each limb will be normalized to limb length as reach distance divided by limb length and multiplied by 100. The two limb values will be averaged. Fatigue-induced change will be calculated as the fatigued value minus the non-fatigued value. The reported outcome will be the Week 10 fatigue-induced change minus the baseline fatigue-induced change.
Time frame: Baseline and Week 10 (post-intervention), assessed under non-fatigued and fatigued conditions
Change From Baseline in Fatigue-Induced Change in Bilateral Mean Normalized Posteromedial Reach Distance
A Y Balance Test Kit (Functional Movement Systems, Inc.) will assess posteromedial reach for both lower limbs under non-fatigued and fatigued conditions at baseline and Week 10. The best valid reach for each limb will be normalized to limb length as reach distance divided by limb length and multiplied by 100. The two limb values will be averaged. Fatigue-induced change will be calculated as the fatigued value minus the non-fatigued value. The reported outcome will be the Week 10 fatigue-induced change minus the baseline fatigue-induced change.
Time frame: Baseline and Week 10 (post-intervention), assessed under non-fatigued and fatigued conditions
Change From Baseline in Fatigue-Induced Change in Bilateral Mean Normalized Posterolateral Reach Distance
A Y Balance Test Kit (Functional Movement Systems, Inc.) will assess posterolateral reach for both lower limbs under non-fatigued and fatigued conditions at baseline and Week 10. The best valid reach for each limb will be normalized to limb length as reach distance divided by limb length and multiplied by 100. The two limb values will be averaged. Fatigue-induced change will be calculated as the fatigued value minus the non-fatigued value. The reported outcome will be the Week 10 fatigue-induced change minus the baseline fatigue-induced change.
Time frame: Baseline and Week 10 (post-intervention), assessed under non-fatigued and fatigued conditions
Change From Baseline in Fatigue-Induced Change in Bilateral Mean Y-Balance Composite Reach Score
A Y Balance Test Kit (Functional Movement Systems, Inc.) will assess the composite reach score for both lower limbs under non-fatigued and fatigued conditions at baseline and Week 10. For each limb, the composite score will be calculated as the sum of the best anterior, posteromedial, and posterolateral reach distances divided by three times limb length and multiplied by 100. The two limb scores will be averaged. Fatigue-induced change will be calculated as the fatigued score minus the non-fatigued score. The reported outcome will be the Week 10 fatigue-induced change minus the baseline fatigue-induced change.
Time frame: Baseline and Week 10 (post-intervention), assessed under non-fatigued and fatigued conditions
Change From Baseline in Maximal Isometric Ankle Dorsiflexion Force
A microFET3 handheld dynamometer will be used to assess maximal isometric ankle dorsiflexion force using standardized participant positioning, joint angle, stabilization, and verbal instructions. Valid trials will be averaged separately for the left and right limbs; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each limb.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Maximal Isometric Ankle Plantar-Flexion Force
A microFET3 handheld dynamometer will be used to assess maximal isometric ankle plantar-flexion force using standardized participant positioning, joint angle, stabilization, and verbal instructions. Valid trials will be averaged separately for the left and right limbs; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each limb.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Maximal Isometric Knee-Extension Force
A microFET3 handheld dynamometer will be used to assess maximal isometric knee-extension force using standardized participant positioning, joint angle, stabilization, and verbal instructions. Valid trials will be averaged separately for the left and right limbs; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each limb.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Maximal Isometric Knee-Flexion Force
A microFET3 handheld dynamometer will be used to assess maximal isometric knee-flexion force using standardized participant positioning, joint angle, stabilization, and verbal instructions. Valid trials will be averaged separately for the left and right limbs; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each limb.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Maximal Isometric Hip-Flexion Force
A microFET3 handheld dynamometer will be used to assess maximal isometric hip-flexion force using standardized participant positioning, joint angle, stabilization, and verbal instructions. Valid trials will be averaged separately for the left and right limbs; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each limb.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Maximal Isometric Hip-Extension Force
A microFET3 handheld dynamometer will be used to assess maximal isometric hip-extension force using standardized participant positioning, joint angle, stabilization, and verbal instructions. Valid trials will be averaged separately for the left and right limbs; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each limb.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Maximal Isometric Hip-Abduction Force
A microFET3 handheld dynamometer will be used to assess maximal isometric hip-abduction force using standardized participant positioning, joint angle, stabilization, and verbal instructions. Valid trials will be averaged separately for the left and right limbs; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each limb.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Maximal Isometric Hip-Adduction Force
A microFET3 handheld dynamometer will be used to assess maximal isometric hip-adduction force using standardized participant positioning, joint angle, stabilization, and verbal instructions. Valid trials will be averaged separately for the left and right limbs; no cross-limb composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each limb.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Maximal Isometric Trunk-Rotation Force
A microFET3 handheld dynamometer will be used to assess maximal isometric trunk-rotation force using standardized participant positioning, joint angle, stabilization, and verbal instructions. Valid trials will be averaged separately for the left and right rotation directions; no cross-direction composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each direction.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Total Lean Mass Assessed by Dual-Energy X-Ray Absorptiometry
A GE Lunar iDXA dual-energy X-ray absorptiometry system will be used to assess total lean mass using standardized participant positioning, scan acquisition, and analysis procedures. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Total Fat Mass Assessed by Dual-Energy X-Ray Absorptiometry
A GE Lunar iDXA dual-energy X-ray absorptiometry system will be used to assess total fat mass using standardized participant positioning, scan acquisition, and analysis procedures. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Total Body Fat Percentage Assessed by Dual-Energy X-Ray Absorptiometry
A GE Lunar iDXA dual-energy X-ray absorptiometry system will be used to assess total body fat percentage using standardized participant positioning, scan acquisition, and analysis procedures. Change from baseline will be calculated as the Week 10 percentage minus the baseline percentage.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Total Body Bone Mineral Density Assessed by Dual-Energy X-Ray Absorptiometry
A GE Lunar iDXA dual-energy X-ray absorptiometry system will be used to assess total body bone mineral density using standardized participant positioning, scan acquisition, and analysis procedures. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in 10-Meter Sprint Skating Time
The time required to complete a 10-meter sprint skating test will be recorded using standardized start, course, and timing procedures. Valid trials will be averaged to obtain one value at each assessment. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in 55-Meter Sprint Skating Time
The time required to complete a 55-meter sprint skating test will be recorded using standardized start, course, and timing procedures. Valid trials will be averaged to obtain one value at each assessment. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in 110-Meter Sprint Skating Time
The time required to complete a 110-meter sprint skating test will be recorded using standardized start, course, and timing procedures. Valid trials will be averaged to obtain one value at each assessment. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Mean Sprint Time During the Repeated-Sprint Skating Test
Completion time will be recorded for each sprint during the prespecified repeated-sprint skating test. Sprint times will be averaged to obtain one mean sprint-time value for each participant at each assessment. Change from baseline will be calculated as the Week 10 mean sprint time minus the baseline mean sprint time.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Number of Laps Completed During the 5-Minute Endurance Skating Test
Roller skating endurance will be assessed as the total number of laps completed during a standardized 5-minute skating test. Change from baseline will be calculated as the Week 10 number of completed laps minus the baseline number of completed laps.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Instantaneous Peak Power During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Instantaneous peak power will be defined as the highest instantaneous power output recorded during the test. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in 3-Second Maximal Power During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Three-second maximal power will be defined as the highest mean power recorded over a consecutive 3-second interval. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in 6-Second Minimum Power During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Six-second minimum power will be defined as the lowest mean power recorded over a consecutive 6-second interval. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Mean Power During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Mean power will be calculated as the average power output over the complete 30-second test. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Relative Maximal Power During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Relative maximal power will be calculated as maximal power output divided by body mass. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Relative Mean Power During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Relative mean power will be calculated as mean power over the 30-second test divided by body mass. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Fatigue Factor During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Fatigue factor will be calculated from the decline between maximal and minimum power according to the prespecified Wattbike analysis method. Change from baseline will be calculated as the Week 10 percentage minus the baseline percentage.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Mean Power During Consecutive 5-Second Intervals of the Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Mean power will be calculated separately for the 0-5, 5-10, 10-15, 15-20, 20-25, and 25-30 second intervals. Results will be reported separately by interval; no cross-interval composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each interval.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Mean Cadence During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Mean cadence will be calculated as the average pedaling cadence over the complete test. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Peak Cadence During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Peak cadence will be defined as the highest pedaling cadence recorded during the test. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Energy Expenditure During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Energy expenditure during the test will be calculated using the prespecified Wattbike analysis method. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Mean Speed During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. Mean speed will be calculated as the average cycling speed over the complete test. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Distance Covered During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. The total distance covered during the 30-second test will be recorded. Change from baseline will be calculated as the Week 10 value minus the baseline value.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Left- and Right-Leg Force Contribution During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. The proportional force contribution of the left and right legs will be recorded separately. No cross-leg composite will be calculated. Change from baseline will be calculated as the Week 10 percentage minus the corresponding baseline percentage for each leg.
Time frame: Baseline and Week 10 (post-intervention)
Change From Baseline in Maximal Force Angle During the 30-Second Wingate Test
A standardized 30-second Wingate test will be performed on a Wattbike WPM Model B cycle ergometer. The crank angle at which maximal force occurs will be recorded separately for the left and right legs. No cross-leg composite will be calculated. Change from baseline will be calculated as the Week 10 value minus the corresponding baseline value for each leg.
Time frame: Baseline and Week 10 (post-intervention)