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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
24
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.
Henan Sport University
Zhenzhou, Henan, China
Change from Baseline to Week 10 in 1-Repetition Maximum (1RM) Back Squat (kg)
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).
Time frame: Baseline and Week 10
1-Repetition Maximum (1RM) Shoulder Press (kg)
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).
Time frame: Baseline and Week 10
Y-Balance Test Composite Score (percent)
Dynamic balance assessed using the Lower Quarter Y-Balance Test. Composite score calculated as ((ANT + PM + PL) / (3 × limb length)) × 100; reported as percent.
Time frame: Baseline and Week 10
Single-Leg Triple Hops (m)
Single-leg triple hop for distance and reported in meters（m）.
Time frame: Baseline and Week 10
Yo-Yo Intermittent Recovery Test Total Distance (m)
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).
Time frame: Baseline and Week 10
T-Test Agility Time (s)
Agility assessed using the T-test; outcome is time to complete the course, reported in seconds (s).
Time frame: Baseline and Week 10
Isokinetic Hip Extension Peak Torque/Body Mass at 60°/s (N·m/kg)
Concentric peak torque for hip extension measured using an isokinetic dynamometer at 60°/s; normalized to body mass and reported as N·m/kg.
Time frame: Baseline and Week 10
Isokinetic Hip Extension Peak Torque/Body Mass at 180°/s (N·m/kg)
Concentric peak torque for hip extension measured using an isokinetic dynamometer at 180°/s; normalized to body mass and reported as N·m/kg.
Time frame: Baseline and Week 10
Isokinetic Knee Extension Peak Torque/Body Mass at 60°/s (N·m/kg)
Concentric peak torque for knee extension measured using an isokinetic dynamometer at 60°/s; normalized to body mass and reported as N·m/kg.
Time frame: Baseline and Week 10
Isokinetic Knee Extension Peak Torque/Body Mass at 180°/s (N·m/kg)
Concentric peak torque for knee flexion measured using an isokinetic dynamometer at 180°/s; normalized to body mass and reported as N·m/kg.
Time frame: Baseline and Week 10
Isokinetic Ankle Extension (Plantarflexion) Peak Torque/Body Mass at 60°/s (N·m/kg)
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.
Time frame: Baseline and Week 10
Isokinetic Ankle Extension (Plantarflexion) Peak Torque/Body Mass at 180°/s (N·m/kg)
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.
Time frame: Baseline and Week 10
Step-back Jump Shot Vertical Impulse (N·s/kg)
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.
Time frame: Baseline and Week 10
Step-back Jump Shot Jump Height (cm)
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.
Time frame: Baseline and Week 10
Squat Jump Height (cm)
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.
Time frame: Baseline and Week 10
Drop Jump Reactive Strength Index (RSI) (m/s)
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.
Time frame: Baseline and Week 10
Change-of-Direction (45°) Braking Impulse (N·s/kg)
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.
Time frame: Baseline and Week 10
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 (%)
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.
Time frame: Baseline and Week 10
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.