Lower limb power and vertical jump
The vertical jump is, for a very long time, the ultimate physical test to determine the muscular power of hockey players. Does the ability of an individual to jump high mean they have good musclar power? Numerous studies have provided a very clear answer to this question. NO, muscle power in hockey players can not be defined according to the height of their jump.
First, when “fitness experts” provide the amount of muscle power from the height of a jump, with a flight time or the vertical speed of the hips, they use estimation equations. There are a variety of different equations which all come to different results. The most popular is probably that of Sayers et al. (1999) :
Power (W) = 51.9 × H (cm) + 48.9 × weight (kg) – 2007
Whichever equation is used, steps from the kinematics (body motion in space) are not able to estimate the power with sufficient precision (Hatze et al., 1988).
The only possible way to get the precise amount of muscle power through the use of a type of platform (Linthorne, 2001). This equipment allows the direct measure of the force applied to the ground by the player during his jump. From this direct measure, one can define with certainty the amount of muscle power in the vertical axis. However, hockey is not a sport that requires to generate vertical power like basketball or volleyball, for example. Jumping forward would be a better representation of hockey. The angles of the lower limb joints will then be much more hockey related.
On the other hand, the fact of adapting the test to hockey does not show a specific measure muscle power. For example, a jump in greater length does not necessarily represent a larger leg power. This is explained by the fact that the technique is a key when performaning a jump. The ability of individuals to jump comes largely from their motor coordination and ability to recruit the right muscles. So the muscle power is not the main factor explaining the height of a jump. This was proven by Tessier et al. (2013) by comparing the jump heights with a forward power measurement with force platform. For this group of athletes, two individuals with the same jump height had power that differed from more than 850 Watts. Knowing that an individual generates an average of 5000 Watts during a jump, a difference of more than 20% is observed.
In conclusion, the vertical jump test does not calculate the muscle power of a hockey player in addition to not being the right representation of the tasks being accomplished in the sport. The first step would be to develop a test that is more of a skating movement. Why not a one leg lateral push?
Written by Léandre Gagné Lemieux, M.Sc. Kinesiology
Hatze H (1998) Validity and reliability of methods for testing vertical jumping performance. J Applied Biomechanics. 14:127-140.
Linthorne NP (2001) Analysis of standing vertical jumps using a force platform. Am J Physics. 69(11):1198-1204.
Sayers SP, Harackiewicz DV, Harman EA, Frykman PN, Rosenstein MT (1999) Cross-validation of three jump power equations. Med Sci Sports Exercise. 31:572-577.
Tessier JF, Basset FA, Simoneau M, Teasdale N (2013) Lower-limb power cannot be estimated accurately from vertical jump tests. J Human Kinetics. 38:5-13.
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