|Author:||Chung, Wai Man|
|Title:||Kinematic and electromyographic analysis of wheelchair fencing|
Hong Kong Polytechnic University -- Dissertations
|Pages:||xix, 279 leaves : illustrations ; 30 cm|
|Abstract:||Wheelchair fencing is a Paralympic sport, in which fencers compete in a fixed wheelchair at a standardized distance. Without the contribution of footwork, wheelchair fencers rely on their arms and trunks to perform all the necessary techniques. Accordingly, substantial stress was placed onto the fencers’ upper extremities; particularly to fencers with deprived trunk control. Currently, no research has yet to be conducted to investigate the injury incidence and risk factors of WF. As such, the first aim of this thesis was to examine and compare the injury patterns between elite able-bodied fencers (AB) and wheelchair fencers (WF); and between wheelchair fencers with- (Category A: CA) and without- (Category B: CB) active trunk control.A 3-year prospective cohort study was performed. Monthly interviews were conducted to the AB and WF from the Hong Kong National Squad to collect the training duration, match duration and injury data. The overall injury incidence rate (3.85/1000 hours) for WF was significantly higher than AB (2.41/1000 hours), p<0.01. Upper extremity injuries were predominant in WF (73.8%). Lower extremity injuries were predominant in AB (69.4%). WF had higher risk than AB in sustaining minor injury (RR: 2.35; 95% CI: 1.56-3.61), muscle strain (RR: 2.16; 95% CI: 1.34-3.56), shoulder injury (RR: 13.55; 95% CI: 3.39-17.76), and elbow injury (RR: 5.90; 95% CI: 2.45-17.21). The CB fencers had higher injury incidence (4.87/1000 hours) than CA fencers (2.99/1000 hours), p=0.02; and higher risk of muscle strain (RR: 1.83; 95% CI: 1.04-3.28) and shoulder injury (RR: 4.97; 95% CI: 1.82-16.87). AB and WF showed distinct injury patterns. WFs with poor trunk control were more prevalent to sustain various shoulder musculoskeletal disorders.The second aim of this thesis was to establish the repeatability of the optical tracking and surface electromyography (SEMG) measurements during the lunge attack of wheelchair fencing. Ten WFs performed lunge attack at their maximal speed to a dummy target at a standardized distance repetitively in a single session. The mean intraclass correlations (ICC₃,₁) for angular displacement was 0.73-0.98 and coefficient of multiple correlation (CMC) was 0.70-0.98. CMC and ICCs for EMG measurement was 0.70-0.94 and 0.62-0.98 respectively. The results indicated that optical tracking and SEMG methods are reliable for examining the upper limb (UL) motion during lunge attacks.|
The third study aimed to compare the agreement of the three-dimensional UL kinematic measurements using optical method and inertial tracking system. Thirty healthy male participants performed shoulder, elbow and wrist movements at their maximum speeds. The Vicon Motion Analysis System and the Xsens MTx sensors simultaneously captured the resulting motions. Pearson’s correlation coefficients for shoulder, elbow and wrist movements were high (0.71-0.99), p<0.01. Joint angles as measured by the two systems lied within the 95% limits of agreement. The results demonstrated high agreements between the two methods for rapid UL motion analysis and substantiate their use for briskly lunge action in wheelchair fencing.The fourth thesis project aimed to compare the kinematic and EMG data between the CA and CB fencers during lunge attack at various fencing distances. Thirty world-class foil WFs (15 CA and 15 CB) performed the lunge attacks to a hitting target at four standardized distances (100%, 105%, 110% and 115% of the normalized fencing distance) in randomized orders. UL kinematic variables (i.e. angular displacement, peak linear velocity, peak angular velocity and cross-correlation coefficient) were computed. SEMG parameters (i.e. peak EMG and integrated EMG, onset and occurrence of peak EMG, and cross-correlation) of the 8 UL muscles (upper trapezius, infraspinatus, anterior-deltoid, mid-deltoid, biceps, triceps, wrist flexors and wrist extensors) were assessed. The results showed that WFs executed a typical powerful lunge attacks by rapidly flexing and abducting their shoulder to 1000-1200 in combination with 500-700 shoulder internal rotation. CB fencers displayed significantly lower peak horizontal and angular velocities, larger angular displacement and altered joint coordination over their shoulder and elbow joints at 110% and 115% of the normalized fencing distance. Compared to CA fencers, CB fencers exhibited a significantly earlier onset of biceps and substantial increase in their shoulder muscle activity (i.e. peak EMG and integrated EMG) at longer fencing distances. The altered kinematics and EMG patterns might represent a unique adaptive shoulder movement strategy used by CB fencers to compensate their poor trunk control as the fencing distance increased. These movement adaptations may demand a larger muscle effort and increase the stress to CB fencers’ shoulders, which may lead to a higher risk of shoulder disorders in this fencer group. This exploratory study revealed differential biomechanical responses between CA and CB fencers during the lunge attack. The results provide the foundation from which to investigate the underlying mechanisms of WF injuries, and to establish injury prevention program or rehabilitation strategies specific to wheelchair fencing.
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