Impact of gender, lunge direction, and fatigue on the lower limb biomechanics in badminton lunges

Abstract

Background: The lunge is a crucial movement in badminton, influenced to different extents by factors such as lunge direction, fatigue, and gender. This study investigates the effects of these factors on lower limb biomechanics to inform strategies for injury prevention and performance optimization.

Methods: Twenty-four amateur badminton players (12 males, 12 females) performed forehand and backhand forward lunges under both fatigued and non-fatigued conditions. Lower limb kinematics and kinetics were recorded using an 8-camera Vicon system and two AMTI force plates. A three-way mixed-design ANOVA was conducted to examine the effects of gender, lunge direction, and fatigue on biomechanical variables.

Results: Forehand lunges demonstrated significantly higher peak joint moments at the hip (extension and external rotation), knee (internal rotation), and ankle (adduction) than backhand lunges. Under fatigued conditions, participants exhibited reduced knee flexion angles and increased leg stiffness. Regarding gender differences, females showed significantly higher knee internal rotation moments and vertical ground reaction force, while males exhibited greater ankle inversion angles. The interaction between gender and lunge direction revealed that males had a significantly smaller hip range of motion in the transverse plane than females, whereas males had greater knee coronal plane range of motion in backhand lunges.

Conclusion: Lower limb movement strategies differ between forehand and backhand forward lunges, with backhand lunges potentially posing a greater risk of ankle injury. Fatigue reduces knee flexion and increases leg stiffness, which may elevate the load on the lower limbs. Gender differences also influence knee moments and ground reaction forces, with females experiencing higher loads. The interaction between gender and lunge direction revealed distinct movement patterns. Females may benefit from targeted hip and knee strengthening exercises to improve lunge performance and reduce injury risk.

Fig 1. Subject markers protocol.

The marker placement locations included the following anatomical landmarks: the brow bone, occipital bone, acromion, C7 vertebra, center of the right scapula, T10 vertebra, center of the clavicle, lowest point of the sternum, anterior and posterior superior iliac spines, medial and lateral femoral condyles, lateral thigh, lateral calf, medial and lateral malleoli, heel, and the first and fifth metatarsal heads.

Fig 2. Schematic diagram of forehand and backhand forward lunges.

(a) indicates the backhand forward lunge, and (b) represents the forehand forward lunge. The dashed line represents 1.5 times the leg length. The X, Y, and Z coordinates are defined according to the force plate. White footprints indicate the position of the left foot, and black footprints indicate the position of the right foot, with numbers indicating the step sequence. FP1 and FP2 represent two different force plates.

Fig 3. Fatigue Intervention.

This fatigue exercise consisted of unlimited repetitions of 5 consecutive vertical jumps (each averaging over 70% of their maximum vertical jump heights) followed by a 30-m sprint (accelerate and decelerate as quickly as possible). This process is repeated until the fatigue criteria are met.

Fig 4. Division of lunge phases.

The forehand forward lunge is used as an example to illustrate the division of lunge phases: (A) Initial contact: the heel contacts the force plate, with vertical ground reaction force > 15 N; (B) Moment of minimum flexion angle in the dominant knee joint; (C) Lift-off: the dominant leg leaves the force plate, with vertical ground reaction force < 15 N. The braking phase is defined as the period from (A) to (B). The recovery phase is defined as the period from (B) to (C). The stance phase is defined as the period from (A) to (C) [10].

Fig 5. Example identification of phases from vertical loading rate and vertical ground reaction force.

The five force phases (a, b, c, d, and e) are identified. BW = body weight; GRF = ground reaction force; LR = loading rate.

Fig 6. Interaction effect of gender and lunge direction on hip transverse plane range of motion (ROM).

Error bars represent 95% confidence intervals.