10-week Complex Training for Chinese National Korfball Players

The Effects of 10-week Complex Training on Physical Characteristics, Biomechanics and Fitness of Chinese National Korfball Players.

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 Overview

• Status: Completed
• Conditions: Athletic Performance; Physical Fitness; Athlete; Fitness Training; Plyometric Exercises; Biomechanical Data
• Intervention / Treatment: Behavioral: 10-week Unilateral Complex Training Program

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Henan
    • Zhenzhou, Henan, China, 054000
      • Henan Sport University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Experimental: 10-week Unilateral Complex Training; Participants will be stratified by sex into two equally sized groups (male and female). All participants will complete the same 10-week unilateral complex training program, which combines resistance and plyometric exercises within each session. No between-group comparisons are planned; analyses will focus on pre- to post-intervention changes.

Behavioral: 10-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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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).	Baseline and Week 10

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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).	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.	Baseline and Week 10
Single-Leg Triple Hops (m)	Single-leg triple hop for distance and reported in meters（m）.	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).	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).	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.	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.	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.	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.	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.	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.	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.	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.	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.	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.	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.	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.	Baseline and Week 10

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body Mass Index (BMI) (kg/m²)	BMI will be calculated as body mass in kilograms divided by the square of stature in meters and reported as kg/m².	Baseline and Week 10
Body Fat Percentage (%)	Body fat percentage will be assessed using a bioelectrical impedance analysis (BIA) body composition analyzer under standardized conditions. Results will be recorded as percent (%).	Baseline and Week 10
Mid-thigh Girth (cm)	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).	Baseline and Week 10
Maximal Calf Girth (cm)	Maximal calf girth will be measured with a non-elastic tape at the level of the largest calf circumference and recorded in centimeters (cm).	Baseline and Week 10
Change from Baseline to Week 10 in Limb Symmetry Index (LSI) for Isokinetic Muscle Strength Test in 180° (%)	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.	Baseline and Week 10
Change from Baseline to Week 10 in Drop Jump RSI LSI (%)	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.	Baseline and Week 10

Collaborators and Investigators

• Sponsor: Universiti Sains Malaysia

Study record dates

Study Major Dates

• Study Start (Actual): July 25, 2024
• Primary Completion (Actual): October 7, 2024
• Study Completion (Actual): October 14, 2024

Study Registration Dates

• First Submitted: September 17, 2025
• First Submitted That Met QC Criteria: December 15, 2025
• First Posted (Actual): December 30, 2025

Study Record Updates

• Last Update Posted (Actual): December 30, 2025
• Last Update Submitted That Met QC Criteria: December 15, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: USM/JEPeM/KK/23110824

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No