The Fatigue Effects of Single-leg Landing in Volleyball Players Cheng-Yu Chen 1, Dian-Ying Lee, 1 Fan-Wu Meng 2, Ke-Chou Chen 2 and Chin-Shan Ho 1 1 National Taiwan Sport University, Taiwan; 2 Chung Yuan Christian University, Taiwan 2012/09/13 1

The fatigue effects affect athletic performance - Introduction 2 A decline in performance Extended time High- intensity Fatigue Neuromuscular control Maximal force or power Potentially hazardous (Bradley et al., 2002; Adlerton et al., 2003; Rahnama et al., 2003; Gabbett et al., 2004; Ribeiro et al., 2007; McLean et al., 2007)

The fatigue effects in jump-landing - Introduction Non-contact knee injuries Jump-Landing Lower-limb neuromuscular control The deleterious impact (Nyland et al., 1997; Wojtys et al., 1996 ; Hawkins et al., 2001 ) 3 Like this

Jump-landing affect the knee - Introduction Picture from: Rebecca Fellin(2006) 4 Jump-landing were one of knee injured mechanism (Louw et al., 2006) 63% of the injuries form jump-landing in Volleyball players (McLean et al., 2007) Anterior shear force were increased from jump-landing (Chappell et al., 2002 ； Shelburne et al., 2004)

Single-leg?! - Introduction 5  Single-leg landing was a frequently phenomenon in volleyball match

The purpose of this study Collecting and analyzing data of volleyball players jump-landing in the dominant-leg.  The knee range of motion (ROM, the initial joint angle to peak joint angle)  The knee moment 6

Subjects - Methods Six college volleyball players (Division I) Over 5 years for volleyball professional training Without the musculoskeletal injuries near one year HeightWeightAges ±10.19 cm73.64±9.06 kg21.5±0.8 yr 7

The fatigue protocol - Methods 30 cm StartEnd 5 M 1. 4 mines 2. As quickly as possible 3. As many times as possible 4. Record heart rate by polar watch Recommend form McLean et al., A series of step-upBounding intensity ①②

Experimental design - Methods The landing task Calculate 50% of the maximum jump height. The first step were into the forceplate. Jumping and touching the target. Landing by the dominant- leg. (Ross et al., 2005; wikstrom et al., 2007) 9

Installation - Methods Vicon T40 motion system  Ten T40 cameras  Vicon Nexus system  Sample rate 200Hz Kistler forceplate  One (90 cmx60 cm)  Vicon Nexus system  Sample rate 1000Hz reflective markers

Data Analyzes - Methods Ground reaction force &Kinematic data Filter by generalized cross-validated (GCV) Calculate the parameter by Visual 3D (Woltring et al., 1986) Defined the parameter with Matlab

Statistical Analyzes - Methods Compare the knee ROMand moment between the non-fatigue and fatigue.  Statistical analyzes by pair-T test of SPSS for Windows 18.0 software  The significance level was α =.05 12

50% of maximum jump height & Average heart rate - Result 50% of maximum jump height: 272.1±10.9 cm Male volleyball net height-243 cm Average maximum heart rate in protocol: beat/min (91%) Maximum heart rate beat/min(220-ages) 13

Non-fatigue Fatigue Visual 3D analyze - Result 14

The knee ROM and peak moment - Result 15 Knee ROM Non-fatigueFatigueP value Flexion59.31± ± * Abduction8.38± ± * Internal rot3.19± ± Peak knee moment Non-fatigueFatigueP value Flexion3.88± ± * Abduction2.19± ± * Internal rot0.46± ±

The effect of fatigue protocol - Discussion General fatigue protocol was simulated the actual game, but also directly affected a particular limb of the proprioception. Cairns et al., 2005, McLean et al., 2005, Miura et al., 2004 In this study, the fatigue effect indeed stand on the subjects after fatigue protocol. 91% of Maximum heart rate 16

Protection → Damage - Discussion  This phenomenon may increased the risk of knee injuries after fatigue protocol. Nyland et al., 1997; Wojtys et al., 1996 ; Chappell et al., Protecting mechanism Time Loading Hewett et al., 2006 The damage

Compensation - Discussion In fatigue, the other muscle groups had been active from jump-landing. Chappell et al., 2005 Past study found that the quadriceps and hip group muscles were been active from the greater knee flexion and abduction. Besier et al., 2003; Hewett et al., 2006; Leetun et al., 2004; McLean et al., 2005 It was possibility increased the knee internal loading from the other muscle groups active. Hewett et al. (2005) 18

Other reasons - Discussion 19 Knee Muscle Spindles Golgi Tendon Organ The Fatigue Effect weaken  The Fatigue Effect were affect the muscle spindles and Golgi tendon organ, and also weaken the stability of knee. Wojtys et al., 1996; Lattanzio et al.,1998; Gandevia et al., 2001

Conclusion In this study, we found that in fatigue: – Knee ROM Flexion and abduction angle were significantly increased. – Knee moment Flexion and abduction moment were significantly greater than the non-fatigue. 20 The fatigue effect may increased the loading on the knee

Thanks for your attention 21