Athlete, Athletic Performance, Biomechanical Data, Fitness Training, Physical Fitness, Plyometric Exercises
Conditions
Brief summary
Korfball is a mixed-gender team sport that requires high levels of coordination, balance, and physical fitness. Unlike basketball or netball, players cannot dribble or run with the ball, and shots must often be taken in a single-leg, step-back position. These unique demands create challenges for athletes' strength, balance, and injury prevention. Despite korfball's growing popularity, scientific research on the sport's physical, biomechanical, and training characteristics remains limited. Complex training (CT) is a training method that alternates heavy resistance exercises with plyometric movements. This approach is known to improve strength, power, sprinting, and jumping ability in other team sports. It is especially relevant for unilateral sports movements, which are common in korfball shooting and defensive actions. However, no studies to date have applied CT to korfball athletes, and the effects of such training on their performance, biomechanics, and interlimb asymmetries are unclear. This study is designed to address three research areas: To describe the internal and external load characteristics of korfball matches using heart rate monitoring and video-based analysis. To investigate limb asymmetry in korfball players through assessments of biomechanics, anthropometry, physical fitness, and shooting technique. To evaluate whether a 10-week unilateral complex training program can reduce limb asymmetry and improve physical fitness and shooting performance in elite players. The study includes both cross-sectional and interventional components. First, competition loads will be monitored to understand game-specific demands. Second, assessments will compare dominant and non-dominant limbs in terms of strength, biomechanics, and technical performance. Finally, athletes will undergo a 10-week unilateral complex training program, after which the same measures will be repeated to test for improvements. The expected outcomes are a clearer understanding of the physiological and biomechanical characteristics of korfball players, as well as evidence on the effectiveness of unilateral complex training. This knowledge may guide coaches and practitioners in designing targeted training strategies to enhance performance, reduce injury risk, and optimize athlete development in korfball.
Interventions
BEHAVIORAL10-week Unilateral Complex Training Program
Participants will undergo a 10-week unilateral complex training program. Each training session combines resistance exercises (e.g., squats, lunges, or weighted lower-limb movements) with plyometric exercises (e.g., jumps, bounding, or explosive step-back movements) performed in alternating sequence. Training is delivered three times per week under supervision. All participants, divided equally by sex, follow the same program. The intervention is designed to improve strength, power, balance, and shooting performance while reducing interlimb asymmetry. No between-group comparisons are planned; outcomes are assessed pre- and post-intervention.
Sponsors
Universiti Sains Malaysia
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Masking description
This is an open-label study; both participants and investigators are aware of the intervention being administered.
Intervention model description
Participants will be stratified by sex into two equally sized groups (male and female). Both groups will receive the same 10-week unilateral complex training intervention. No between-group comparisons are planned; analyses will focus on within-group pre- to post-intervention changes.
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Male or female athletes aged 18 to 35 years. * Selected for the China National Korfball Team or the China Youth National Korfball Team. * Able to participate in the full training and testing protocol and willing to provide informed consent.
Exclusion criteria
* Participation in structured physical training other than korfball training within the previous 6 months. * History of cruciate ligament injury, fracture, or other significant injury affecting sports performance within the previous 12 months. * Failed routine musculoskeletal health screening or has unresolved injury/medical condition that precludes safe participation. * Does not meet baseline strength prerequisites required for safe participation in complex training (combined resistance and plyometric exercises) according to NSCA guidelines. Additional notes (for study procedures, not eligibility): -Participants will complete an information questionnaire to document training history and basic characteristics.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change from Baseline to Week 10 in 1-Repetition Maximum (1RM) Back Squat (kg) | Baseline and Week 10 | Maximal lower-body strength assessed as the one-repetition maximum (1RM) load for the barbell back squat. Participants completed standardized warm-up sets followed by progressive single attempts to determine the maximal load successfully lifted once with correct technique; rest periods were provided between attempts. The outcome is the 1RM load, reported in kilograms (kg). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Isokinetic Hip Extension Peak Torque/Body Mass at 180°/s (N·m/kg) | Baseline and Week 10 | Concentric peak torque for hip extension measured using an isokinetic dynamometer at 180°/s; normalized to body mass and reported as N·m/kg. |
| Step-back Jump Shot Vertical Impulse (N·s/kg) | Baseline and Week 10 | Vertical GRF impulse (Z-axis) during the propulsion phase of the step-back jump shot, computed as the time integral of the Z-axis GRF over propulsion and normalized to body mass (N·s/kg). Registered value = bilateral mean; limb-specific (left/right) values will be reported as additional analyses. |
| Step-back Jump Shot Jump Height (cm) | Baseline and Week 10 | Jump height during the step-back jump shot will be derived from force-plate-defined flight time and reported in centimeters (cm). The registered outcome value will be the bilateral mean; limb-specific values will be reported as additional analyses. |
| Squat Jump Height (cm) | Baseline and Week 10 | Squat jump height derived from force plate data (flight-time method ) and reported in centimeters (cm). Registered value = bilateral mean; limb-specific values reported as additional analyses. |
| Drop Jump Reactive Strength Index (RSI) (m/s) | Baseline and Week 10 | Reactive Strength Index (RSI) during drop jump, calculated as jump height (m) divided by ground contact time (s); reported as m/s. Registered value = bilateral mean; limb-specific values reported as additional analyses. |
| Change-of-Direction (45°) Braking Impulse (N·s/kg) | Baseline and Week 10 | Braking GRF impulse in the sagittal axis (Y-axis) during the 45° change-of-direction task, computed as the time integral of the braking-direction portion of the Y-axis GRF over the braking/weight-acceptance interval (initial contact to peak knee flexion) and normalized to body mass (N·s/kg). The registered outcome value will be the bilateral mean; limb-specific values (left/right) will be reported as additional analyses. |
| Change from Baseline to Week 10 in Overall Shooting Accuracy Across 3 m, 5 m, and 7 m in a 1-Minute Timed Shooting Protocol (%) | Baseline and Week 10 | Shooting accuracy will be assessed using a standardized sport-specific timed shooting protocol at three distances (3 m, 5 m, 7 m). At each distance, participants will attempt as many shots as possible within 1 minute. The number of successful shots and total shot attempts will be recorded at each distance. The registered outcome value will be overall shooting accuracy (%) aggregated across all three distances, calculated as: (total successful shots across 3 m+5 m+7 m ÷ total shot attempts across 3 m+5 m+7 m) × 100. Distance-specific accuracies (3 m, 5 m, 7 m) will be analyzed and reported as additional analyses. |
| 1-Repetition Maximum (1RM) Shoulder Press (kg) | Baseline and Week 10 | Upper-body maximal strength assessed as the one-repetition maximum (1RM) load for the shoulder press exercise. The 1RM is defined as the maximal load that can be lifted once with correct technique for the specified exercise; the outcome is the 1RM load, reported in kilograms (kg). |
| Y-Balance Test Composite Score (percent) | Baseline and Week 10 | Dynamic balance assessed using the Lower Quarter Y-Balance Test. Composite score calculated as ((ANT + PM + PL) / (3 × limb length)) × 100; reported as percent. |
| Single-Leg Triple Hops (m) | Baseline and Week 10 | Single-leg triple hop for distance and reported in meters（m）. |
| Yo-Yo Intermittent Recovery Test Total Distance (m) | Baseline and Week 10 | Intermittent running performance assessed using the Yo-Yo Intermittent Recovery Test Level 1 (YYIR1). Performance is defined as the maximal total distance completed, reported in meters (m). |
| T-Test Agility Time (s) | Baseline and Week 10 | Agility assessed using the T-test; outcome is time to complete the course, reported in seconds (s). |
| Isokinetic Hip Extension Peak Torque/Body Mass at 60°/s (N·m/kg) | Baseline and Week 10 | Concentric peak torque for hip extension measured using an isokinetic dynamometer at 60°/s; normalized to body mass and reported as N·m/kg. |
| Isokinetic Knee Extension Peak Torque/Body Mass at 60°/s (N·m/kg) | Baseline and Week 10 | Concentric peak torque for knee extension measured using an isokinetic dynamometer at 60°/s; normalized to body mass and reported as N·m/kg. |
| Isokinetic Knee Extension Peak Torque/Body Mass at 180°/s (N·m/kg) | Baseline and Week 10 | Concentric peak torque for knee flexion measured using an isokinetic dynamometer at 180°/s; normalized to body mass and reported as N·m/kg. |
| Isokinetic Ankle Extension (Plantarflexion) Peak Torque/Body Mass at 60°/s (N·m/kg) | Baseline and Week 10 | Concentric peak torque for ankle extension (plantarflexion) measured using an isokinetic dynamometer at 60°/s; normalized to body mass and reported as N·m/kg. |
| Isokinetic Ankle Extension (Plantarflexion) Peak Torque/Body Mass at 180°/s (N·m/kg) | Baseline and Week 10 | Concentric peak torque for ankle extension (plantarflexion) measured using an isokinetic dynamometer at 180°/s; normalized to body mass and reported as N·m/kg. |
Other
| Measure | Time frame | Description |
|---|---|---|
| Mid-thigh Girth (cm) | Baseline and Week 10 | Mid-thigh girth will be measured with a non-elastic tape at the midpoint between the inguinal crease and the proximal border of the patella, perpendicular to the long axis of the thigh, and recorded in centimeters (cm). |
| Maximal Calf Girth (cm) | Baseline and Week 10 | Maximal calf girth will be measured with a non-elastic tape at the level of the largest calf circumference and recorded in centimeters (cm). |
| Change from Baseline to Week 10 in Limb Symmetry Index (LSI) for Isokinetic Muscle Strength Test in 180° (%) | Baseline and Week 10 | LSI will be calculated for concentric knee extension peak torque at 180°/s as: LSI = (dominant limb / non-dominant limb) × 100, reported as percent (%). Peak torque will be normalized to body mass (N·m/kg) before LSI calculation. Dominant limb defined a priori. |
| Change from Baseline to Week 10 in Drop Jump RSI LSI (%) | Baseline and Week 10 | LSI will be calculated for drop jump Reactive Strength Index (RSI) as: LSI = (dominant limb / non-dominant limb) × 100, reported as percent (%). RSI will be computed as jump height (m) divided by ground contact time (s) for each limb. Dominant limb will be defined a priori. |
| Body Mass Index (BMI) (kg/m²) | Baseline and Week 10 | BMI will be calculated as body mass in kilograms divided by the square of stature in meters and reported as kg/m². |
| Body Fat Percentage (%) | Baseline and Week 10 | Body fat percentage will be assessed using a bioelectrical impedance analysis (BIA) body composition analyzer under standardized conditions. Results will be recorded as percent (%). |
Countries
China
Outcome results
None listed