By Carl Valle
I have been doing jump analysis for a long time, and each year the problems and challenges tend to actually grow, not diminish. Currently, a mad dash for more jump data is causing many programs in sports training to actually give up testing entirely, because the main needs of coaches are not being taken care of. Specifically, this means making the information part of real day-to-day decision-making or bringing enlightenment to the program.
Contact mats are an excellent way to benchmark change, but are often thought of as replacements to force plates because of calculations after having the same units of power. In this article, two important components will be fully explained in detail. The first is what contact mats can and cannot do with jump testing with athletes. The second is how to implement simple testing in a way that obeys the laws of sport science without making it a burden to coaches.
Why Jump Test?
Before I recommend any protocol or technology, the most obvious question that coaches must answer is why they are testing in the first place. The responses are often overly complicated or not even useful on paper—just regurgitated pop sport science that isn’t practical or meaningful. Many coaches are not familiar with how to actually do the jumps they believe are being tested, like the squat jump, for example. If they want jump data, it’s likely they want to connect the information to the following:
Talent Identification – Jump testing is an easy way to measure the explosive abilities of athletes, even at youth levels. The ability to jump high is frankly just the ability to jump high, and some limits exist on anybody being able to extrapolate a mainly vertical jump into an ability to play a sport. Generally speaking, someone explosive has the potential to use that ability if they are groomed and coached up, but again, no one quality is a silver bullet.
The ability to jump high is frankly just the ability to jump high, and some limits exist on anybody being able to extrapolate a mainly vertical jump into an ability to play a sport.
Risk Analysis and Return to Play – Most coaches are aware of the importance of eccentric strength, but they don’t test for it. Additional needs in injury reduction like right and left symmetry, along with a return to previous training ability, can be included as well. Many coaches are wary of the vague use of the term “return to play” because the ability to play doesn’t always coincide with being prepared in the way that got them there.
Performance Enhancement – An obvious need for jump testing is to see change in the development of an athlete, whether long-term or during an important phase, like evaluating an off-season period. Unfortunately, most of the time variables that are performance qualities are not indicative of what is actually being developed because so many variables make a strong conclusion a bit foggy. My favorite example is a combination, when an athlete training for an absolute test gives great scores in athletic power, but much of the data must be taken with a grain of salt. The argument that great test results don’t guarantee great sports performance, especially in team ball sports, is a waste of time.
Clearly, jump testing isn’t going to predict the next 100-meter record holder or Super Bowl champion, but the data has relevance when used properly. The goal is to use the context of the information and come to reasonable conclusions as to why things are happening or not, with training based on a case-by-case approach to each athlete individually.Jump testing data has relevance when used in context to come to reasonable conclusions. Click To Tweet
Monitoring Power and Fatigue – Given the rise of technology, a popular approach is sampling neuromuscular changes with weekly jump testing of teams. This methodology, while well-intentioned and likely administered well, is harder to do than most expect. Some coaches have chased RFD (rate of force development) with research-grade force plates, and some have looked at other metrics, hoping to see neurological fatigue or recovery. What can be determined is that only severe drops in power, along with other data points, give confidence to the conclusion, and only when the athlete is cooperative and motivated in the process.
Note: Most coaches will look at jump testing as a way to look at leg power; specifically, relative abilities compared to one’s body weight. This is a good general summary, but I will later explain the limitations to specificity and transfer with any type of jump.
All of the above can be done with different success rates, but be warned: Don’t think that even one valid measure is enough to make a solid decision. Sometimes confounding variables make interpretation difficult, no matter how great the technology is or how carefully the athlete follows a protocol.
The Anatomy and Physiology of a Jump
Jump testing can range from something as simple as height in a vertical jump to a very demanding assessment of foot contact pressure profiles during a fraction of a second. Several types of jumps and protocols, and various technologies, can result in data, but to get the signal from all of the noise, you have to think about realistic expectations. Jump testing and jump training are not the same thing, and each athlete is highly variable because of their personality and values, not just their physical DNA. Jump assessment and implementation of testing is an art and science, and it’s better to use it correctly, but less frequently, than to use it all the time and hope to get more value from using a measurement more. Daily HRV assessment makes sense, but going to the gym and doing a jump test before every workout is ineffective.
When deciding to add jump testing, you must take five things into consideration. They are:
1. Type of Jump – Jumps are a wide option, and the variations of each movement can create a firestorm of debate with both sport scientists and coaches. The key to jump evaluation is being fluent with the specific types in the literature and ensuring that the technique matches what is shared from the literature and replicated with the athletes tested. The first lesson is to be aware of the difference between jumps, hops, bounds, and so forth. The way in which someone takes off and lands varies a lot, and the misnomer terms can create confusion, such as hurdle hops (two-legged jumps over hurdles) with track and field.
A coach should not only know the jump tests, but they should also know all of the variations and training details that are arguably more important. It’s better to have an athlete bound and hop with great ability on the field than to have an athlete do squat jumps and countermovement jumps (CMJ) well in the weight room. Testing and training aren’t mutually exclusive; they can be done concurrently, but some jump testing often has very little training influence.
2. Protocol or Procedure – Details in testing make jump analysis useful when the instructions make the data reliable and precise. Accurate and valid assessments are harder to do, because many technologies simply measure one part of a complex action. Coaches should focus on making sure the athletes perform the tests as well as they can, so inflated changes don’t happen from gaming the data or from familiarization. Athletes often appear to look the same because they learn to do the activity better and get instant feedback, but at the same time fatigue neutralizes those changes. Thus, you can’t get too excited with data that varies from early testing. Coaches often use the term “baseline,” but the calendar of sport doesn’t always match the biology of athletes. Remember that jump testing is only one piece of the puzzle, even when just comparing test to test.
3. Sequence of Sampling – Coaches need to pick their battles at the right time in the right order. Testing too frequently leads to athletes losing motivation, and testing on the wrong day can actually backfire with sports psychology. Training and competition loading make it difficult to find an ideal time for jumping, but don’t worry that each week has to be perfectly replicated in order to have value. If you choose a testing day too soon after a match, athletes will be spooked, thinking they are getting weak. However, if you test too close before a game, they may get a case of self-fulfilling thinking that could create issues with team chemistry and coaching relationships. Testing before or after practice is also a variable, so this is something that must be individualized based on each team’s own situation.Training and competitions make it difficult to find time to test. Do what works best for your team. Click To Tweet
4. Transfer Value – A popular question (and need) is how the jump test correlates to other abilities, as some jumps are more valuable than others and some are very limited. An example common to coaches is vertical or horizontal jumps having more validity based on the way they connect specifically to narrow qualities of athleticism. Another example of transfer is the style of jump, like an NFL lineman starting statically before they explode or a basketball player tipping a rebound to themselves in a game. Coaches should note that it’s better to get a direct measure than rely too much on transfer extrapolation, as even a great relationship is never as sensitive or precise.
5. Data Type Collected – A last, but very important, consideration with jump testing is what type of data is collected, not what information is reported. A big leap of faith (pardon the pun) between a calculation and a direct measure exists with jump testing. Much of the data limitations will come from the way the numbers or measures were collected, including the protocol and equipment used. For example, you need a force plate if you want to calculate right and left power. Contact mats and other systems estimate power by assuming the flight path is not abused, and even the most careful of assessments will have errors.
High-precision data from force plates is indeed the gold standard, but coaches that can’t afford this technology must accept proxy data that’s less accurate. A healthy perspective is knowing how well the data will fit the actionable decisions afterward, and what faith in the numbers you can possibly have if you do it right. As the technology becomes less direct, it’s important to have it be more of a traffic light than a microscope.
Getting good data is not just about having a big budget: It’s having a comprehensive plan to make sure that a lot of data can be collected and that every jump will matter.
Video 1: This shows the Push Band device used with the weighted repeat squat jump. The takeoff velocity and peak bar velocity are similar but not interchangeable metrics. Also, arm English during jumps can give inflated readings if the jumps are not controlled, thus making it very sensitive to technique.
What sounds easy on paper is much harder when you have to take large groups of athletes and try to do something intelligent and efficient. Before you even shop around or debate the value of jump testing, every factor must be ironed out. Getting good data is not just about having a big budget: It’s having a comprehensive plan to make sure that a lot of data can be collected and that every jump will matter.
Common Technologies Used in Jump Testing
A core point of this article is for the reader to understand the differences in technology and what each one does best. I have used more than a dozen tools, ranging from $100 to $50K or more. Yes, you get what you pay for, and many people go cheap and then complain later when their data looks like Powerball lottery numbers instead of something useful and valid. The secret of investing in technology is knowing what’s important with the system, as it’s not just a linear process of more is better.
Contact mats are not force plates. Pressure mats are not force plates. Contact mats are an option in a category of equipment that simply sees a binary indication of the athlete being in the air or on the ground. This is why other products that use optical sensors are part of the family of contact mats, even if they have no landing surface. Again, the purpose of the contact mat is to sample at a reasonable frequency, in order to know that someone is on it or someone is in the air from propulsive forces. The data it provides is very direct, and the time between the contacts and the rest must be assumed rather than measured.
Force plates measure exactly what is implied in their name—the force delivered to the contact surface with strain sensors. Air time can be misleading, as landing technique and other factors can make the data a bit tainted and limited, but that’s why force plates are research solutions and intended for elite athletes. The margin of error is far smaller, but the high price tag is the reason they’re not found in every high school right now. Additionally, the strength of force plates lies in the ability to align them bilaterally for symmetry—something that nearly every coach wants.
Linear positional transducers (LPTs) and accelerometers attempt to get velocity curves based on time and distance through calculations using the hardware. The Gymaware and 1080 Quantum systems can sample displacement with high frequency to give good velocity indicators, but they are not perfect jump tools. However, they offer excellent feedback for training options.
While this is very good data for many purposes, coaches constantly make the mistake of believing that power data coming from the calculations is valid for interchangeable comparison. Most coaches will not pollute their composite scores with a mixed environment, but this is being done countless times without them knowing. As the data becomes less direct and more distant from the ground or center of mass (COM), you can be less confident about real sensitive measures. If you don’t have a force plate it doesn’t mean you can’t jump test—it’s just that the expectations must be toned down a notch and the benefits must be pruned to what the sensors can measure. A good analogy is to look at force plate as an MRI, and the contact mat as an x-ray. It’s not a perfect analogy, but a line in the sand exists with the quality and usefulness of the data.
Optical sensors, like infrared bars from Microgate, are better positioned for step data or good for coaches who want to use cleats on the grass—something a contact mat can’t do. Surfaces are specific, but field testing outside isn’t perfect because Wi-Fi is spotty at times and glare or rain can make electronics a pain to use because of power and safety. Decide on what you need based on what you will likely be able to influence in training. Consider the budget of years as well.A very strong protocol coached well and done with motivation can give very useful solid data. Click To Tweet
As all of the technology improves, expect common needs like speed and simplicity to increase workflow. Information will also become more accessible as the systems decrease in cost. Still, don’t wait for the next big thing with jump technology, as we have not seen a quantum leap (pardon the pun again) with innovation here. A very strong protocol coached well and done with motivation can give solid data so that you know when something doesn’t look good and when to continue going full steam ahead.
Performing the Bosco Tests and More
The most popular jump tests are the Bosco tests, from the Italian scientist Carmelo Bosco. Dr. Bosco’s jump series is validated and useful for nearly any sport, and most technologies support his protocols. I have written briefly about his tests with the Raptor Test, and Dr. Marco Cardinale was great in sharing how to do them in a blog here. My problem with most of the literature is that much of the research on getting people to do the tests better and the nuances that may affect the tests is absent.
With contact mats, we need to know that flight times are sensitive to being abused, so even athletes who are being honest with their landing technique will accidently still game the hang time slightly. This is OK for managing them, but not for sharing absolute abilities. Again, think about consistent jump protocols. You don’t necessarily have to stress accuracy when you want to see change, and not just pure data. Here are some tips on performing the Bosco Tests and other popular jump measures.
The Squat Jump
Video 2: The jump here is a typical passing test based on how stationary the athlete is before exploding, and the specific joint angle of the torso and knee. The prevalence of the vertical jump with arm swings usually influences the jump test technique. Some software with force plates can detect if the jump test has too much body dip or center of mass drop, reducing the need for interpretation. Automation can lead to frustration from the athlete, but tighter data quality improves when subjective measurement is removed.
Static position jumps remove the eccentric component of the jump, and I like the squat jump because it allows a joint angle to be roughly 90 degrees. Some coaches use their eyes, some use benches, some use video software. I like using an LPT. Instead of putting your hands on their hips like the traditional method, athletes can use a dowel or light training bar to keep the jumps repeatable. Video synchronization with force plates makes this a snap, but because not everyone will have access to this, it’s a good idea to film and then measure the best jumps later.
The Countermovement Jump
Video 3: The landing of the countermovement determines how far off the jump estimate is from the force analysis of research instrumentation. When an athlete lands the way they start it’s hard, as athletes tend to allow a knee bend, thus raising the score slightly. Also athletes must stick the landing or the jump is not valid, as most that don’t stick the landing are artificially trying to increase the air time. The jump technique above is sufficient for monitoring deep fatigue, but will not allow for absolute talent identification.
One problem with the countermovement jump is depth. The athlete is actively trying to come down rapidly, while the squat jump just needs someone to follow direction. I have always said in sprints that block start angles should never be poorly implemented because angles in a static position just require an athlete to practice and follow directions, not have talent. The same can be said for squat jumps, but countermovement jumps are more skilled as they obviously have more “moving parts.” The other area to look for is the positions of the knee and hip, as athletes who jump with their arms well are sometimes poor jumpers without their arms because of two factors.
First, and most obvious, everyone who is properly trained can create more displacement or height using their arms. Like the squat jump, removing the arms or momentum contribution reduces the total score and deflates egos. Second, arm actions usually create a bigger hip bend and more of a folding and unfolding effect, which creates more time to gather force and a mechanically advantageous position for some athletes. Some athletes try to jump quickly instead of jumping high, making this test a learning demand for some.
Video 4: When rebound jumping is done properly, it removes much of the gaming of the test quality that athletes do both consciously and subconsciously. Since one has to load properly again, the landing strategy employed by the athlete is likely to be the most effective to produce force again. Rebounding requires coaching: As the video demonstrates, longer contact times are not ideal, and would not be a great Reactive Strength Index (RSI) option. If you want valid RSI scores, focus on getting jump height by applying force with a stiffer joint system, cued appropriately.
Rebound jumping is even more open to interpretation because technique is less agreed on and the goal of the jump test is just as murky. Rebound jumps are continuous jumps, but the details and style can help you see even more information if they’re added to the previous two tests. A central need with rebound jumps is to make sure athletes know what is expected because, unlike the previous two jump tests, this exercise requires multiple bouts of effort. Athletes must know what the goal is before testing.
Maximum air time and minimal contact time should focus on the head getting high. Typically, the joint positions are minimal knee and hip, and a small reduction in the ankle complex as well. Since rebound jumps are mainly about ratios of flight and ground time, power calculations are more for visual purposes than something someone would use in analysis. The total contact time, as well as the ratio, is important, since many athletes may have similar ratios but the way they get there is a little different.
Bigger angles are from “gatherers,” who use strength and some eccentric ability. Athletes who have smaller contact times usually create reactive forces better and might be more talented below the knee. Some tests require almost a straight leg and try to see ankle stiffness: We see this with athletes who look like they have boots on. The addition of this test has recently gained interest in some circles.The Reactive Strength Index is becoming popular in the U.S., and contact mats do well testing this. Click To Tweet
The Reactive Strength Index, or RSI, is growing in popularity in the U.S., for good reason. The score is easy to do and provides a fresh data point that is more likely to be connected to neurological status because the time frames are shorter. Contact mats are actually best positioned for RSI testing because flight times and contact times are ratios. Several alternative tests, like the RSI Modified, are freely available: The most important point to remember is to make sure the population matches with the test style, if possible.
Future Directions With Contact Mat Data
One area I didn’t talk about much is the human side of things—getting people to jump with all-out effort. This is perhaps the most important factor that is seldom talked about because it’s a little embarrassing: Sometimes athletes will not jump, no matter how hard or high you want them to. Things like injuries, fatigue, and boredom make simple Bosco tests or even performing the Raptor Series difficult. Clearly, some entertainment and motivational efforts must be included so jump testing is more engaging, but even those gimmicks will get old.
The most direct way to get buy-in is to share how you make decisions and the cost of not putting in an honest effort. Obviously, this isn’t a perfect solution, as some athletes will still not care and may not jump or will jump without effort. Think about how many times even athletes stop practicing on their own in order to play in much more interesting activities like slam dunk contests or pick-up games of volleyball. A good way to look at contact mats is as an instrument to help you get the right information to know very clear areas that you would be incapable of getting just by looking with your eyes. Aim for a balance between objective and subjective data to help foster relationships and drive better programming in training.
Suggested Reading and References
- A wonderful primer on the CMJ and technology can be found at the Science for Sport website. These five overlapping studies are also all excellent reviews.
- Ache Dias, J, Dal Pupo, JD, Reis, DC, Borges, L, Santos, SG, Moro, ARP, and Borges Jr., NG. “Validity of two methods for estimation of vertical jump height.” J Strength Cond Res 25(7): 2034–2039, 2011.
- Bosco, C, Luhtanen, P, and Komi, PV. “A simple method for measurement of mechanical power in jumping.” Eur J Appl Physiol Occup Physiol 50: 273–282, 1983.
- Glatthorn, JF, Gouge, S, Nussbaumer, S, Stauffacher, S, Impellizzeri, FM, and Maffiuletti, NA. “Validity and reliability of Optojump photoelectric cells for estimating vertical jump height.” J Strength Cond Res 25: 556–560, 2011.
- Markovic, G., D. Dizdar, I. Jukic, and M. Cardinale. “Reliability and factorial validity of squat and countermovement jump tests.” J Strength Cond Res 18(3): 551–555. 2004.
- Nuzzo, JL, Anning, JH, and Scharfenberg, JM. “The reliability of three devices used for measuring vertical jump height.” J Strength Cond Res 25: 2580–2590, 2011.