Technically, power can be defined as force times distance divided by time. In practice the expression of power allows an individual to sprint, jump, throw objects, lift explosively and complete rapid changes of direction while travelling at speed. These attributes are vital for many sporting and athletic endeavours as well as many everyday activities.
Power can be tested in several ways, some complex and some relatively simple. For a power test to be useful to the trainer it should be able to be performed with limited equipment in a variety of environments. Power tests that require a wide array of expensive equipment may be suited to the sports science laboratory environment, but they are of limited practical use to the general trainer.
This section will introduce and explain a number of easily applied tests that assess power performance.
Who Should Perform the Tests?
Power testing will not be appropriate for all clients. When selecting a test for any component of fitness the trainer should consider the principles of fitness testing: accuracy, client care and appropriateness of the test.
The trainer must assess if the client has achieved a suitable level of physical preparedness to be able to perform the power tests safely. As all of the tests in this section involve jumping, it would be inappropriate to use the power tests on a client that was injured, obese, pregnant, hypertensive or at the beginner stage with respect to physical conditioning. The benefits of assessing vertical jump height would be heavily outweighed by the risks of the test if the client was physically unprepared to sustain the impact of landing from a maximal effort jump.
If the client’s training programme contains some element of power training it would be appropriate to perform the power tests both before and after the power phase. This will allow the trainer to monitor any performance enhancement and modify the training programme accordingly. Using re-testing to demonstrate to the client that they have achieved a performance improvement can be highly motivating. It can also reinforce the client’s faith in the ability of their trainer and justify their investment with respect to time, money and effort.
At risk groups:
As mentioned previously these tests will not be suited to all individuals. Clients that appear on the following list should not perform the power tests explained within this section:
- novice clients
- clients with musculoskeletal injuries or pain in the lower extremities or spine
- pregnant females
- clients with hypertension
- obese clients
- elderly clients (unless still involved in power activities / training)
- clients diagnosed with osteoporosis
- clients with any medical condition or injury that concerns either trainer or client
- fatigued clients
As many of the power tests in this section involve jumping it is important to educate clients as to safe landing procedure. Landing a maximal jump carries with it an inherent risk of musculoskeletal injury. Areas under significant stress include the ankles, knees, hips and spine. The ground reaction forces (GRF) experienced when landing will vary depending on the height of the jump. Kreighbaum & Barthels (1996), suggest that a vertical jumper will experience a GRF of 2-3 times bodyweight on landing. When landing from a height of 1 metre the body will experience a GRF of around 9 times bodyweight. The trainer must therefore, ensure that the client is physically able to participate in the test chosen (see contraindications list above).
To safely land from a jump it is important that the client absorbs the impact through appropriate use of the lower body musculature. The client should aim to land on the balls of their feet, with their knees flexed and their chest over their knees (Boden et al, 2000). A rapid eccentric contraction of the plantarflexors starts to decelerate the downward momentum. Simultaneous, eccentrically controlled flexion of both knees and hips will allow the client to decelerate the downward momentum gradually, thus ‘absorbing the shock.’
Vertical jump tests.
Vertical jump tests can be performed in two distinct ways, the squat jump (SJ) and the countermovement jump (CMJ). Both assess the ability of the musculature of the hips, thighs and lower leg to propel the individual vertically into the air, but the CMJ utilises the elasticity in muscles and the stretch-shortening cycle whereas the SJ does not. If the trainer wishes to perform just one variant of the vertical jump test then the CMJ is probably more appropriate as it more closely replicates the way the body loads then unloads in function.
Countermovement jump (CMJ)
- a smooth wall with a ceiling higher than the jumper can reach
- a flat floor with good traction
- chalk of a different colour than the wall
- measuring tape or ruler
- the client rubs chalk on the fingertips of their dominant hand
- the client stands side on to the wall with the shoulder of their dominant hand about 15cm from the wall
- with their feet flat on the floor the client reaches as high as they can and makes a chalk mark on the wall
- the client then performs a maximal countermovement jump. The countermovement requires the client to rapidly flex the hips and knees, bring the torso forward and down and swing the arms behind the body. This is the eccentric loading phase of the stretch-shortening cycle
- the concentric phase of the jump should instantly follow the eccentric loading phase. The client rapidly extends both hips and knees while simultaneously swinging the arms upward
- at the top of the jump the client should make a second chalk mark with their fingertips
- the trainer then measures the vertical distance between the two chalk marks with the tape measure or ruler
- the best of three trials is recorded and taken as the client’s test score
The procedure for the squat jump is similar to the CMJ. The only difference is that the jump is initiated from an isometrically held, partial squat position. The trainer should ensure that there is no movement from the client for a period of 2 seconds once the partial squat position has been adopted. Measurement of the squat jump is recorded in the same way as for the CMJ.
|Normative table for vertical jump performance (CMJ)|
|Performance % Rank||Female height (cm)||Male height (cm)|
|91-100 World class||76-81||86-91|
Note that the normative table above is derived from data obtained from elite athletes competing at world class level. Inappropriate use of this type of table could be very demotivating for the average client, as they are likely to rank within a very low percentile. Trainers are advised to exercise caution when comparing clients to normative tables of any kind. Test scores are more appropriately used to monitor a client’s progress against their own previous performances.
The table on the below shows average vertical jump performances obtained from a variety of population groups.
|Vertical jump performance for various populations (CMJ)|
|Population group||Vertical jump height (cm)|
|18-34 year old males||41|
|recreational male college athletes||61|
|competitive male college athletes||64-65|
|18-34 year old females||20|
|recreational female college athletes||38-39|
|competitive female college athletes||41-47|
Adapted from Newton (2002)
The vertical jump tests are particularly useful for clients that participate in sports or activities that require powerful vertical leaping for successful performance. Examples of such sports would be basketball, netball, volleyball, high jumping and certain positions in rugby.
Standing broad jump:
Like the vertical jump tests the standing broad jump can be performed almost anywhere with limited equipment. It can also be performed with or without a countermovement. The countermovement broad jump is by far the more common variation of the test.
The standing broad jump tests are useful for individuals that participate in activities that require powerful horizontal movements. Examples of such activities would be the long jump, triple jump and sprinting.
- flat surface with good traction
- tape measure
- straight line marked on the floor
- the client starts with their feet shoulder width apart, and their toes behind the line marked on the floor
- the client swings their arms behind the body and simultaneously initiates a countermovement from their knees and hips (performs a ¼ to ½ squat)
- the client swings their arms forward and extends knees and hips to leap explosively forward as far as possible
- the trainer marks the back heel of the client and measures the distance between this mark and the start line
- the best score of 2-3 trials is recorded
The trainer can conduct a non-countermovement jump by instructing the client to adopt a static semi-squat position behind the starting line prior to the jump phase. This squat must be held statically for 2 seconds prior to the jump.
|Normative table for standing broad jump performance (CMJ)|
|Performance % Rank||Female distance (m)||Male distance (m)|
|91-100 World class||2.94-3.15||3.40-3.75|
Standing triple jump:
A variation of the standing broad jump is the standing triple jump test. This assesses horizontal distance covered over three successively performed maximal efforts. It is a useful method for evaluating the effectiveness of the stretch-shortening cycle, as well as leg power, co-ordination and balance.
This test requires the individual to generate and sustain forward momentum through 3 phases, a hop, step and jump. The equipment required is the same as for other variants of the standing broad jump, although a longer jumping area will be required.
- the client stands with their feet shoulder width apart and their toes behind the starting line
- the client performs a countermovement and pushes forwards off both feet as far as possible
- the client lands on one foot and immediately projects forward on to the opposite foot
- the client concludes the test by immediately projecting forwards to land on both feet
- the trainer records the distance from the start line to the back heel of the client
- the client may attempt the test 2-3 times with the furthest distance recorded as the test result
|Normative table for standing triple jump performance|
|Performance % Rank||Female distance (m)||Male distance (m)|
|91-100 World class||8.15-8.85||9.80-10.50|
Boden, B. Griffin, L. & Garrett, W. (2000). Etiology and prevention of noncontact ACL injury. The physician and sports medicine. 28 (4)
Chu, D. (1996). Explosive strength and power: complex training for maximum results. Human Kinetics
Harman, E. & Pandorf, C. (2000). Principles of test selection and administration. Ch. In Essentials of strength training and conditioning, Baechle, T. & Earle, R. (Eds). Human Kinetics
Kreighbaum, E. & Barthels, K. (1996). Biomechanics. A qualitative approach to studying human movement. 4th Ed. Allyn and Bacon
Newton, H. (2002). Explosive lifting for sports. Human Kinetics