Original articles  EXERCISE PHYSIOLOGY AND BIOMECHANICS 

The Journal of Sports Medicine and Physical Fitness 2003 December;43(4):418-23

Copyright © 2009 EDIZIONI MINERVA MEDICA

lingua: Inglese

A comparison between land and sand-based tests for beach volleyball assessment

Bishop D.

Western Australian Institute of Sport, laremont, Australia

Aim. Ver­tical-­jumping ­ability is crit­ical for suc­cess in ­beach vol­ley­ball. How­ever, as ­beach vol­ley­ball is a rel­a­tively new ­sport, its ­testing pro­ce­dures ­have ­largely ­been ­adopted ­from the ­indoor ­game and are con­se­quently per­formed on ­firm sur­faces. The pur­pose of ­this ­paper was to deter­mine ­whether ver­tical-­jumping ­ability is spe­cific to the ­test sur­face (i.e., ­wood or ­sand).
­Methods. ­Eighteen ­beach vol­ley­ball ­players per­formed ­4 dif­ferent ver­tical ­jumps on a ­wood sur­face or on the ­sand, fol­lowed by the alter­nate sur­face, in a ­random, coun­ter­bal­anced ­order. Cor­re­la­tion coef­fi­cients ­were cal­cu­lated to deter­mine the ­degree of asso­ci­a­tion ­between the 4 ­jumps and ­between the ­test ­results on the 2 sur­faces.
­Results. ­When com­pared ­with the ­land con­di­tion, all ­jump ­heights ­were sig­nif­i­cantly ­lower ­when per­formed on ­sand (p<0.05). ­There was how­ever, a sig­nif­i­cant cor­re­la­tion ­between the ­land and ­sand ­results for all ­jumps (­mean r=0.93; p<0.05). ­While all ­4 ver­tical ­jump vari­a­tions ­were sig­nif­i­cantly cor­re­lated ­with ­each ­other (mean r=0.91; p<0.05), the cor­re­la­tion ­between ­static ­jumps and the ­spike ­jump (3-­step run up) ­tended to be ­lower.
Con­clu­sion. It is ­likely ­that ver­tical ­jump ­height on ­sand is ­lower ­than on ­land due to a reduc­tion in the ­ground reac­tion ­force. How­ever, ­despite ­this, the ­strong cor­re­la­tion ­between ­land and ­sand ­scores sug­gests ­that ver­tical-­jumping ­ability ­exists as a gen­eral ­quality and is not ­greatly influ­enced by ­test sur­face in the sub­jects ­tested. ­This sug­gests ­that ­land-­based ­tests can be ­used to ­assess ­sand ­jumping ­ability in expe­ri­enced ­beach vol­ley­ball ­players.