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Biomechanical Analysis of Jumping: T...

Barker, Leland A.

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Biomechanical Analysis of Jumping: The Influence of External Load and Countermovement Depth on Deceleration Strategies and Performance.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Biomechanical Analysis of Jumping: The Influence of External Load and Countermovement Depth on Deceleration Strategies and Performance./
Author:	Barker, Leland A.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2018,
Description:	110 p.
Notes:	Source: Dissertation Abstracts International, Volume: 80-02(E), Section: B.
Contained By:	Dissertation Abstracts International80-02B(E).
Subject:	Biomechanics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10822154
ISBN:	9780438460225

Biomechanical Analysis of Jumping: The Influence of External Load and Countermovement Depth on Deceleration Strategies and Performance.
Barker, Leland A.

Biomechanical Analysis of Jumping: The Influence of External Load and Countermovement Depth on Deceleration Strategies and Performance. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 110 p.

Source: Dissertation Abstracts International, Volume: 80-02(E), Section: B.

Thesis (Ph.D.)--University of Nevada, Las Vegas, 2018.

Jumping performance has traditionally been measured by jump height alone. In recent years, the reactive strength index (RSI = Jump height / jump time)) has been used as another measure of jump performance. According to RSI, which was developed to assess eccentric force production, jump performance can improve by increasing jump height, decreasing jump time, or both simultaneously. However, it is not clear how force production correlates to RSI variables. If RSI is meant to be a practical measure of eccentric force production, it should correlate strongly to eccentric and amortization force production during jumping. Thus, the purpose of the first study was to determine the relationship between ground reaction force (GRF) variables to jump height, jump time, and the Reactive Strength Index (RSI). Twenty-six Division I male soccer players performed three maximum effort CMJs on a dual-force platform system that measured three-dimensional kinetic data. Vertical GRF (Fz) variables were divided into unloading, eccentric, amortization, and concentric phases and correlated to jump height, RSI (RSI= Jump height/jump time), and jump time (ground contact time from start to takeoff). Significant correlations were observed between jump height and RSI, concentric kinetic energy, peak power, concentric work, and concentric displacement. Significant correlations were observed between RSI and jump time, peak power, unload Fz, eccentric work, eccentric rate of force development (RFD), amortization Fz, amortization time, 2nd Fz peak, average concentric Fz, and concentric displacement. Significant correlations were observed between jump time and unload Fz, eccentric work, eccentric RFD, amortization Fz, amortization time, average concentric Fz, and concentric work. In conclusion, jump height correlated to variables derived from the concentric phase only, while Fz variables from the unloading, eccentric, amortization, and concentric phases correlated highly to RSI and jump time. These observations demonstrate the importance of countermovement Fz characteristics for time-sensitive CMJ performance measures. Further, RSI correlated strongly to Fz variables during eccentric and amortization phases. Researchers and practitioners should include RSI to improve their assessment of jump performance.

ISBN: 9780438460225Subjects--Topical Terms:

548685
Biomechanics.

Biomechanical Analysis of Jumping: The Influence of External Load and Countermovement Depth on Deceleration Strategies and Performance.
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100 1 $a Barker, Leland A. $3 3427923
245 1 0 $a Biomechanical Analysis of Jumping: The Influence of External Load and Countermovement Depth on Deceleration Strategies and Performance.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2018
300 $a 110 p.
500 $a Source: Dissertation Abstracts International, Volume: 80-02(E), Section: B.
500 $a Adviser: John Mercer.
502 $a Thesis (Ph.D.)--University of Nevada, Las Vegas, 2018.
520 $a Jumping performance has traditionally been measured by jump height alone. In recent years, the reactive strength index (RSI = Jump height / jump time)) has been used as another measure of jump performance. According to RSI, which was developed to assess eccentric force production, jump performance can improve by increasing jump height, decreasing jump time, or both simultaneously. However, it is not clear how force production correlates to RSI variables. If RSI is meant to be a practical measure of eccentric force production, it should correlate strongly to eccentric and amortization force production during jumping. Thus, the purpose of the first study was to determine the relationship between ground reaction force (GRF) variables to jump height, jump time, and the Reactive Strength Index (RSI). Twenty-six Division I male soccer players performed three maximum effort CMJs on a dual-force platform system that measured three-dimensional kinetic data. Vertical GRF (Fz) variables were divided into unloading, eccentric, amortization, and concentric phases and correlated to jump height, RSI (RSI= Jump height/jump time), and jump time (ground contact time from start to takeoff). Significant correlations were observed between jump height and RSI, concentric kinetic energy, peak power, concentric work, and concentric displacement. Significant correlations were observed between RSI and jump time, peak power, unload Fz, eccentric work, eccentric rate of force development (RFD), amortization Fz, amortization time, 2nd Fz peak, average concentric Fz, and concentric displacement. Significant correlations were observed between jump time and unload Fz, eccentric work, eccentric RFD, amortization Fz, amortization time, average concentric Fz, and concentric work. In conclusion, jump height correlated to variables derived from the concentric phase only, while Fz variables from the unloading, eccentric, amortization, and concentric phases correlated highly to RSI and jump time. These observations demonstrate the importance of countermovement Fz characteristics for time-sensitive CMJ performance measures. Further, RSI correlated strongly to Fz variables during eccentric and amortization phases. Researchers and practitioners should include RSI to improve their assessment of jump performance.
520 $a The first study observed a strong relationship between jump performance and force production during the eccentric and amortization phases. But, there is limited research on force production during eccentric and amortization phases of the jump squat (JS), which is a countermovement jump performed with external load via barbell. Further, limited research has investigated the influence of countermovement technique on these variables. Therefore, the second and third studies investigated the effect of load and countermovement technique on kinetics during the eccentric and amortization phases of the jump squat. The second and third studies used the same protocol: On day one, participants performed a 3-repetition maximum (RM) back squat. On day two, participants performed JS with 0%, 15%, 30%, 45%, and 60% of estimated 1-RM using three countermovement techniques: preferred (PREF), quarter (QTR), and full (FULL) depths. Participants wore flat athletic shoes, and were outfitted with reflective markers on the lower extremity to collect 3D kinematics. JS were performed on dual force platforms synchronized with the 3D data.
520 $a The purpose of the second study was to compare vertical ground reaction forces (Fz) from the eccentric and amortization phases of the JS across loads and countermovement techniques. A convenience sample of 12 healthy, resistance-trained men (24.8 +/- 4.04 yrs, 86.71 +/- 15.59 kg, 1.78 +/- 0.79 m, 3-RM Back Squat: 123.2 +/- 23.79 kg) were recruited from the university kinesiology department. Dependent variables included: (1) eccentric rate of force development (RFD1 and RFD2); (2) first Fz peak (Fz1); (3) amortization Fz and time; (4) jump height; (5) RSI; (6) peak and average concentric power; (7) and countermovement depth. Eccentric RFD1 did not change with increasing loads (p > 0.05), but eccentric RFD2 decreased with increasing loads (p 0.05), but was greater with load (15%--60% of 1-RM) than without (0% of 1-RM). Jump height and RSI declined with increasing loads (p < 0.05), and power peaked using 15% and 30% of 1-RM. The QTR JS resulted in greater amortization Fz, RSI, peak power, and average power (p < 0.05). Based on the second study, it is recommended that QTR techniques be used in conjunction with FULL or PREF techniques throughout a comprehensive training plan purposed for development of stretch-shortening cycle performance.
520 $a The purpose of the third study was to compare joint kinetics from the eccentric and amortization phases of the JS across loads and countermovement techniques. A convenience sample of 10 healthy, resistance-trained men (24 +/- 4.24 yrs, 88.35 +/- 16.71 kg, 178.15 +/- 7.15 cm, 3-RM Back Squat: 119.27 +/- 21.78 kg) were recruited from the university kinesiology department. (Abstract shortened by ProQuest.).
590 $a School code: 0506.
650 4 $a Biomechanics. $3 548685
650 4 $a Kinesiology. $3 517627
690 $a 0648
690 $a 0575
710 2 $a University of Nevada, Las Vegas. $b Kinesiology and Nutrition Sciences. $3 3427924
773 0 $t Dissertation Abstracts International $g 80-02B(E).
790 $a 0506
791 $a Ph.D.
792 $a 2018
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10822154