Muscular power and vertical jump

The vertical jump has long been the physical test par excellence for determining the muscular strength of field hockey players. Does an individual’s ability to jump high really represent his muscular power? Numerous studies have provided a very clear answer to this question. NO, the muscular power of field hockey players cannot be defined in terms of their jump height.

First of all, when “fitness specialists” give muscle power from jump height, flight time or vertical hip speed, they use estimating equations. There’s a whole range of different equations, all with different results. The most popular is certainly that of Sayers et al. (1999):

Power (W) = 51.9 × H (cm) + 48.9 × weight (kg) – 2007

Whatever equation is used, measurements derived from kinematics (body movement in space) do not allow power to be estimated with sufficient accuracy (Hatze et al., 1988).

The only way to obtain precise muscle power is to use a form platform (Linthorne, 2001). This type of equipment directly measures the force applied to the ground by the player during the jump. From this direct measurement, we can define with certainty the muscular power for an action in a vertical axis. However, field hockey is not a sport that requires vertical power generation like basketball or volleyball, for example. To better represent field hockey, it would be better to take a leap forward. The joint angles of the lower limbs will then be much more representative of field hockey.

On the other hand, adapting the test to the specificities of field hockey doesn’t make it any easier to measure muscle power. For example, a bigger long jump doesn’t necessarily mean greater leg power. This is because technique is a key element in jumping performance. An individual’s ability to jump is largely determined by their motor coordination and their ability to recruit the right muscles. So muscular power is not the main factor explaining the height of a jump. This was proven by Tessier et al. (2013) when comparing jump heights with a direct power measurement using a force platform. For this group of athletes, two individuals with the same jump height could have a power output that differed by more than 850 Watts. Given that an individual generates an average of 5000 Watts during a jump, this represents an error of over 20%.

In conclusion, the vertical jump test cannot be used to calculate a field hockey player’s muscular power, and is not representative of the player’s sporting task. Until strength platforms are affordable both financially and in terms of ease of use, jump tests can continue to be useful to coaches and physical trainers, provided they are adapted to field hockey. The first step would be to develop a test that profiles the skating movement more closely. How about a one-legged push?

Written by Léandre Gagné Lemieux, M.Sc. Kinesiology

References:
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.