Clegg hammer measures and human external landing forces : is there a relationship?

Saunders, Natalie, Twomey, Dara and Otago, Leonie 2011, Clegg hammer measures and human external landing forces : is there a relationship?, International journal of sports science and engineering, vol. 5, no. 4, pp. 231-236.

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Title Clegg hammer measures and human external landing forces : is there a relationship?
Author(s) Saunders, NatalieORCID iD for Saunders, Natalie
Twomey, Dara
Otago, Leonie
Journal name International journal of sports science and engineering
Volume number 5
Issue number 4
Start page 231
End page 236
Total pages 6
Publisher World Academic Union (World Academic Press)
Place of publication Liverpool, England
Publication date 2011
ISSN 1750-9823
Keyword(s) Clegg hammer
sport surface
Summary Ground hardness is deemed an important consideration for player safety for sports played on natural turf surfaces. Currently, a ground hardness measure is being determined using a Clegg hammer, with the suitability for play dependent on an acceptable reading. This study aimed to examine whether a relationship between Clegg hammer readings and ground reaction forces (GRF’s) generated by a human during a drop landing exist. Fifteen male community level Australian football players were recruited for the study. Participants performed a single leg drop landing on the right leg from a 45cm box onto the force plate to record GRF’s. Ten trials were conducted for three conditions: no shock pad, thin shock pad (15mm) and thick shock pad (50mm) under a synthetic turf sample. Four consecutive Clegg hammer readings were recorded following each set of ten trials. Variables of interest were maximum vertical GRF (Max vGRF), maximum rate of loading (Max RoL) and Clegg hammer (CH) readings. Pearson’s Correlation Coefficient was conducted to examine the relationship between variables and conditions. Slight to fair relationships were found between the Max vGRF and any of the four CH drops (0.181 ≤r≥ 0.189; p ≤ 0.01). This finding was similar to the relationship with Max RoL (0.209 ≤r≥ 0.217; p ≤ 0.01). When analysed for the specific shock pad condition, the relationships remained poor (r <0.1; p ≥ 0.29), with the exception of the Max RoL and the CH readings on the thick shock pad (0.1 ≤r≥ 0.2; p ≥ 0.03). The results of this study show that the ground reaction forces experienced by a human on different levels of surface hardness are significantly different to the forces on impact of the Clegg hammer. Consequently, the Clegg hammer may not be the most appropriate device for relating surface hardness to player safety, thus it is possible that the Clegg hammer alone is insufficient in globally determining ground safety.
Language eng
Field of Research 110699 Human Movement and Sports Science not elsewhere classified
Socio Economic Objective 920409 Injury Control
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2011, World Academic Press, World Academic Union
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Collections: Faculty of Health
School of Exercise and Nutrition Sciences
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