Diminishing Returns

It seems that there is a relatively clear divide between lab and field tests- laboratory tests tend to be more expensive, more specific in terms of the variables you can look at, and require a greater amount of technical expertise. Field tests on the other hand, are generally much cheaper, give less specific information, and are usually easier to operate.  I don’t think that I could break this down and say that one class of tests is particularly better than one another, they just serve different ends.

For the sake of example, let’s look at vertical jump testing.  On the laboratory side, you can use a force plate, optojump, potentiometers and myotest, to name a few.  It is my personal bias, but I prefer force plate testing out of those options, simply because I’m most familiar with them, and I am interested in the ground reaction forces inherent in an athlete/ground system. Force plates can give you a slew of variables, from peak power and peak force, to impulse and jump height.  I don’t believe there is an alternative that is as useful as a force plate in terms of jump testing, especially when you consider the huge volume of data you can get from a single jump on a plate. However, there are a number of drawbacks to using force plates – they are heavy, usually big, often expensive, and require special computer interfaces to collect the data.  For your average coach, these draw backs are far too high to justify using a force plate.
On the other end of the spectrum, there is the option of using a Vertec, seen below.  The Vertec is a quick, easy way to get a good measure of an athlete’s explosiveness and ability to overcome their body mass.  You can get simple vertical leap, or approach jumps, or even drop jumps.  It isn’t all that expensive, and can give you some great performance information.  There is one unfortunate drawback to the Vertec – and that is the fact that technique, specifically arm swing, can affect vertical jump performance1.  When you are trying to evaluate a person’s progress, do you really care if their vertical jump technique got better or if their lower body got more powerful?  Of course the answer is the latter! Athletes going in the combine are coached all the time in how to reach higher and hit a higher tab (even if they aren’t jumping any higher). I’m not saying that the Vertec is a bad test, not by any means.  However, it is important to keep what can affect the test in the back of your mind when and if you use it.

Source: http://georgebeckham.com/wp-content/uploads/2013/02/verteclg-241×300.jpg
So here lies the middle ground – a switch mat. These devices run off of a simple electrical circuit – when you stand on the mat, the switch is closed, when you are in the air, the switch is open.  The switch mat is able to calculate jump height based on flight time (time between closings of the switch).  The fact that the “reach” is out of the picture can make a big difference in your accuracy of measurement.  Further, using a switchmat, you can take the arms out of the picture, by placing hands on hips, or by holding a virtually weightless PVC pipe across the back.  This ensures that you are really measuring explosive performance, and not just jumping technique. Switchmats aren’t perfect – one of the biggest considerations you have to keep is that the athlete must initially hit the mat on the way back down in the same position they left it.  If they land with bent legs, the flight time is artificially increased, and the jump height estimation will be off.
Not having to deal with the “reach” lets you do a number of other tests as well (besides the variations you can do with the Vertec).  One option is to use loaded vertical jumps in your testing protocol, because it gives you a measure how well an athlete performs under supra-body mass loads.  We are interested in how the athlete is able to overcome loads greater than body mass, like they might see when contacting another player (i.e. soccer, football), or when changing direction (high loading on a single leg).  While the vertical jump is not exactly specific to COD or players fighting for position, it might give us a bit more idea how they might perform in that situation (see reference 2 for an example – loaded jump variables differentiated between junior and senior elite rugby players).
It all comes down to determining what information you want, how specific you need to be and what your budget and time constraints are. There is certainly no best way to track progress, but there are many better ways to do things.  The trick is figuring out which ones are best for you and your athletes.

References:
1. Lees, A., Vanrenterghem, J., Clercq, D. D. (2004). Understanding how arm swing enhances performance in the vertical jump. Journal of Biomechanics 37(12). p 1929-1940. Found at: Link
2. Hansen, K. T., Cronin, J. B., Pickering, S. L., Douglas, Lee. (2011) Do Force–Time and Power–Time Measures in a Loaded Jump Squat Differentiate between Speed Performance and Playing Level in Elite and Elite Junior Rugby Union Players? Journal of Strength and Conditioning Research 25(9) p 2382-2391. Found at: Link

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