If you’re not assessing your guessing is a phrase often used in the world of strength and conditioning and sports science. The principle being that without concrete data it is difficult to pinpoint where the training focus should be or assess if the training intervention has been successful. Advances in technology have seen an increased use of different devices for data collection with athletes. Apps on your phone can tack bar speed, jump height, and sprint speed. The availability of portable force plates have made the assessment of force time variables such as Force, Impulse and rate of force development (rfd) more accessible to trainers and coaches of all levels. Technology provides us with the opportunity to gain more detailed information more quickly than ever before, but practitioners should ask themselves two questions before using the data from any new device;
- Is it Valid & Reliable?
- Is my standardisation of testing adequate to ensure reliable data?
Validity refers to the extent to which an instrument is measuring what it is supposed to measure, if it proposes to measure bar speed, does it do just that? Typically, any measurement device is compared to “gold standard” of measurement.
Reliability refers to the consistency or repeatability of a measure. A test cannot be valid if it is not reliable, however a test can be reliable but not valid.
A more detailed blog on reliability can be viewed here
Just recently Perez-Castilla et al. 2019 Link published an interesting paper comparing the validity and reliability of 7 commercially available barbell velocity tracking devices which highlighted the varying standards of reliability there are among such devices.
If reliability data is not freely available, the onus is on the practitioner to at least perform some in house reliability work to assess their own reliability as a tester.
Standardisation refers to the set up and execution of testing procedure. Bosco (1999) reported that on a contact mat, jump height could be overestimated by as much as 16% by landing relatively flat footed rather than within the feet plantar flexed. With valid reliable phone apps such as Myjump Link , this can be more readily controlled and invalid trials can be disregarded.
Not assessing is definitely guessing, but garbage in, garbage out is another phrase to keep in mind! If our data collection method is poor and unreliable, using it to direct or make decisions on the effectiveness of training can be largely ineffective and inefficient.
Portable force plates have become increasingly more common in many private practices and teams. Potentially the force plates allow a greater depth of information to provide on an athlete’s jump strategy, instead of merely assessing jump height, the coach can now see what mechanisms the athlete used to achieve this height. Similarly, the Isometric Mid-Thigh Pull (IMTP) is a very popular method of assessing maximum force and other force time variables. A quick scan of social media can highlight the IMTP popularity for testing among s&c coaches and sports scientists, unfortunately, we tend to see the tests performed in such a manner that don’t lend themselves to providing meaningful data. Consider the set up for the IMTP, frequently we can observe practitioners using standard Olympic bars in weight racks for collecting IMTP data. This is likely to skew our rate of force development and force data significantly. The Olympic bar is designed to bend and have some degree pliability, good for Olympic lifting, but not good for IMTP data collection, the movement in the bar and often in the rack itself, causes excessive noise and disturbance in the data, especially if we are seeking to assess rate of force development, which tends to be an inherently unreliable measure to assess in lots of tests Link . We also need to ensure the athlete is strapped or taped to the bar in a consistent manner, without straps there is a significant loss of grip for the athlete which also affects the maximum force the athlete can achieve. Is the athlete in the correct starting position? Is there a dip or countermovement at the start of the pull which will affect where of start of movement is identified in the force time trace curve and consequently affect the reliability of force, impulse and RFD measures. Is the athlete familiar with the test? With any test, it is crucial that the athlete is familiar with the set up and execution of the test, increased familiarisation tends to lead to increased reliability and therefore better data.
Data collected must be actionable, it must serve a purpose and have a direct consequence on the next phase of training or recovery. If the data we collect doesn’t inform some aspect of training or have any input on your chose key performance indicators, we shouldn’t really be collecting that data in the first place! With any piece of sports technology, can we determine its validity and reliability, and then can we refine our set up and standardising process to improve the quality of our data collection.
Ciaran Keogh is a postgraduate research in the Department of Physical Education and Sport Sciences at the University of Limerick. His current research interests include strength and conditioning, motor typing of athletes and exercise physiology. You can contact Ciran via email at Ciaran.Keogh@ul.ie