Supertraining

Members may be interested in the below abstract (NSCA conference abstracts 
2008):

VARIABLES ASSOCIATED WITH OPTIMAL DROP VERTICAL JUMP STARTING HEIGHT

Andrea K. Wilson, Lawrence W. Weiss, Brian K. Schilling

Plyometric jump training is often used for sports requiring explosive leg and 
hip movements. Intensity during the initial eccentric phase of jumps may be 
manipulated by using various drop vertical jump (DVJ) heights. It is likely 
that an optimal height exists that would elicit optimal jumping performance, 
and that the optimal height will vary based on subjects' individual 
characteristics. PURPOSE: The aim of this study  was to identify the 
association between the box height producing maximum performance (vertical 
displacement and reactive strength index or RSI, jump height/contact time) and 
potential independent predictors such as gender, strength, stature, body mass, 
body composition, and muscle mechanical properties.

METHODS: Subjects were evaluated for gender, height, body mass, body 
composition, 1RM squat, and muscle stiffness. Following familiarization, 
subjects completed DVJs from four starting heights: 20cm, 40cm, 68cm, and 77cm.

RESULTS: Spearman's Rho correlation analyses revealed significant
correlations between box height for maximum vertical displacement and gender 
(&#961;=&#8208;0.447, p<.01), subject stature (&#961;=.366, p<.05), body mass 
(&#961;=.415,p<.01), and 1RM squat (&#961;=.324, p<.05). None were 
significantly correlated with box height for maximum RSI. For gender specific 
analyses, no significant correlations were found between optimal box height for 
maximum vertical displacement and the independent variables. However, a 
significant correlation existed for men between optimum box height for
maximum RSI and bodyfat (&#961;=.711, p<.01). Chi square testing indicated no 
significant difference in frequencies between
optimal starting heights for maximum vertical displacement (total and
gender&#8208;specific samples). There was, however, a
significant difference in frequencies for RSI for both the sample (&#967;² 
=24.90, p<.01) and data split between male subjects
(&#967;² =8.00, p<.05) and female subjects (&#967;² =9.58, p<.01).

CONCLUSIONS:
It appears that optimal DVJ starting height is not
highly related to the independent measures examined in this research.

PRACTICAL APPLICATIONS: Based on these findings, it is suggested that DVJ 
testing over a broad range of starting heights should be used to determine 
which height produces optimal performance.

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Jamie Carruthers
Wakefield, UK