The counter-movement jump (CMJ) is a movement that is utilized in nearly every sport. An athlete may perform a CMJ when going up for a rebound in basketball, receiving a pass in football, making a block in volleyball, and so on. When you break a CMJ down to its fundamental characteristics you find more than the simple act of jumping. At its core, the CMJ is the explosive extension of the hips, knees, and ankles. This movement can be mimicked and loaded through traditional weightlifting movements like the snatch and clean. Loaded movements present an easy model of improvement with load increases scaling up with training. If you want to know how many apples are in an orchard, you count the apples – not the apple trees. When we use jumps as a metric for power, we’re comparing apples to apples.
The training room and the sports arena are not the same environments. The relevance of performance testing is most accurate the more closely it resembles the movements performed by an athlete in their respective sport. In training we expect jump height and body mass to change over time as an athlete experiences changes in power development and body composition. This can happen in any number of ways to produce different outcomes. For example, jump height might decrease in a collegiate athlete in the off season due to a disproportionate loss of lean mass to fat mass. Likewise, jump height can increase due to a loss of fat mass with no change in lean mass. A stable body composition hopefully yields an increased jump height after pre-season training with a block of plyometric training. With these shifting outcomes, our barometer to a successful training program is through determining peak power. Studies have appropriately shown this to be the case by normalizing power to body mass and body fat.1,2 The Sayers equation3 can be used to see if changes in body mass and jump height are favorable to our training objectives.
PEAK POWER (WATTS) = [60.7 _JUMP HEIGHT (CM)] + [45.3_ BODY MASS (KG)] – 2055
Some examples of how this works for a single individual over the course of a training cycle:
An increase in jump height from the first time point to the second is modest at best. Peak power increases by almost 320 watts, but relatively speaking this fairly consistent performance with an increase in mass shows no power development when you observe differences in relative peak power. However, even with a modest drop in body mass, peak power is amplified by such a steep increase in jump height. A shallow look tells us an increase of 530 watts, but training really shines by taking a measure relative to their current mass, showing a larger jump from the second trial to the third trial. Generally speaking, we can see the effect of training longitudinally, but all see the marked difference between functional mass and non-functional mass. Without peak power as a metric, we’re limited in our conclusions as compared to simple jump height.
A case study by Haines and Deacon in 2014 analyzed relative peak power in a male elite volleyball player. They made comparisons of relative peak power assessed through a CMJ and a loaded CMJ across a 23 week training program. Trend differences from baseline mirrored each other, within roughly 4%, only showing a large departure at taper at closer to 9%. Both showed sensitivity to strength training volume and intensity and appeared to reflect decrements resulting from a high volume of power endurance.
Performing the test Previous methods of testing can be conducted using a vertical arm with a pivoting system to determine jump height.5 Alternatively, it’s possible to use a wall and chalk marking system to denote jump height, both subtracting for body height with the arm extended. Another common method uses a pressure and release switch timer to calculate displacement between leaving the ground and landing.5 The standout limitation of these is the facility requirements and/or ease of implementation.
With a scale, a PUSH band, an accompanying waist band, and a flat surface, the test can be performed in almost any setting. Athlete profiles can be edited from the PUSH Portal, or on the fly using the application on the iPod/iPad. The PUSH unit is threaded through the waist belt, with the sensor placed on the small of the back.
Switch to the athlete’s profile and select tests icon (Fig 1).
Select the CMJ – Arm Swing test. This will display a description of the exercise (Fig 2).
Activate the unit (it will turn from red to green), perform the jump, and press the activation button again (it will turn green to red).
The iPod/iPad will give summary metrics (Fig 3). Pressing the analytics tab will give you additional information, such as peak velocity superimposed on average velocity (Fig 4), or peak and average power (Fig 5).
Upon returning to the tests section (Fig 1), the most recent jump height will be displayed.
Returning to the CMJ test description will display previous tests by date (Fig 2).
Utility and application
The CMJ gives a solid read on peak power as it applies directly to most sports. This is not limited to just performance testing though. In terms of athletic monitoring, it can give a solid gauge of preparedness based on physical outcomes.6 Monitoring physical outcomes (such as power) is easy to communicate, and can therefore be more actionable than other measurements. Convoluted measurements of blood glucose, respiratory exchange ratio, or other physiological measures don’t translate as readily to coaches, athletes, and strength and conditioning coaches as well as direct measures of performance. Performance outcomes are not only more actionable, but give a measure that correlates highly to physiological metrics like neuromuscular status.
The system offered by PUSH allows for multiple stations to run simultaneously with few facility restrictions. Rather than pulling antiquated equipment from storage in many facilities, the multifaceted piece of equipment that the PUSH Band is can supersede old testing methods.
Another advantage specific to PUSH, is the streamlined approach in which flights of athletes can be efficiently imported to PUSH Portal (Figure 6). The data syncs to the Portal, allowing progress to be monitored over time (Figure 7). Export functions allow the data to be pooled to provide team and position comparisons. Much like the testing process with PUSH, data management is simplified. As a professional strength and conditioning coach this gives you a streamlined approach to communicating progress.
And lastly, if the testing process was so easy, why wouldn’t you do it?
- Markovic G, Jaric S. Scaling of muscle power to body size: The effect of stretch-shortening cycle. Eur J Appl Physiol. 2005;95(1):11-19. doi:10.1007/s00421-005-1385-5.
- Nedeljkovic a, Mirkov DM, Bozic P, Jaric S. Tests of muscle power output: the role of body size. Int J Sports Med. 2009;30(2):100-106. doi:10.1055/s-2008-1038886.
- Sayers SP, Harackiewicz D V, Harman EA, Frykman PN, Rosenstein MT. Cross-Validation of Three Jump Power Equations.; 1999. doi:10.1097/00005768-199904000-00013.
- Haines B, Deakin G. Longitudinal neuromuscular monitoring tool: a case study using bodyweight vs loaded countermovement jump. J Aust Strength Cond. 2014;22(5):37-40.
- Miller T. NSCA’s Guide to Tests and Assessments. (Miller T, ed.). Champaign, IL: Human Kinetics; 2012.
- Langley M. Athlete Monitoring and Frequency of Feedback. 2016. http://www.trainwithpush.com/blog/athlete-monitoring-frequency-of-feedback-by-mark-langley.