SJ-IMTP test
The SJ-IMTP test is used to measure an athlete’s dynamic strength index (DSI).
Learn how to effectively carry out tests on your athletes without spending a penny. You’ll master performance testing, field tests, gym tests and more for free.
By Owen Walker
18th Feb 18 | 4 min read
Contents of Article
Although the Static SJ-IMTP is an accurate and reliable measure of an athlete’s Dynamic Strength Index, it can be problematic to conduct due to the requirements of complex and expensive equipment (i.e. force platforms). Nonetheless, it provides the strength and conditioning coach or sports scientist with novel information regarding the athlete’s force producing capacity.
Keywords: squat jump, SJ, IMTP, isometric mid-thigh pull, strength deficit, strength diagnosis, peak force.
Though it appears somewhat complicated, this test is actually very simple and is used to measure an athlete’s Dynamic Strength Index. The Dynamic Strength Index (DSI), otherwise known as the Dynamic Strength Deficit [1] or the Explosive Strength Deficit [2-4], is simply a ratio between an athlete’s ballistic peak force and their dynamic or isometric peak force [5]. This can be used to identify whether the athlete may require maximal strength training, ballistic strength training, or concurrent training (i.e. a combination) as a stimulus in their programme [6]. It can also be used to reliably measure the performance capabilities in both the lower- and upper-body and in recreational, university, and elite athletes.
Firstly, the Static SJ refers to the Static Squat Jump, and the IMTP is the abbreviation for the Isometric Mid-Thigh Pull. The Static SJ is a dynamic ballistic exercise, whilst the IMTP is an isometric exercise. Using both of these tests and comparing the results, the practitioner is able to identify the athlete’s strengths and weaknesses when it comes to producing force.
For a more in-depth discussion on the Dynamic Strength Index (inc. why to measure it) – CLICK HERE
To learn more about the Squat Jump – CLICK HERE
It is important to understand that whenever fitness testing is performed, it must be done so in a consistent environment (e.g. facility) that it is protected from varying weather types, and with a dependable surface that is not affected by wet or slippery conditions. If the environment is not consistent, the reliability of repeated tests at later dates can be substantially hindered and result in worthless data.
Required Equipment
Before the start of the test, it is important to ensure you have the following items:
Testing Procedure
Warm-up
Participants should thoroughly warm-up prior to the commencement of the test. Warm-ups should correspond to the biomechanical and physiological nature of the test. In addition, sufficient recovery (e.g. 3-5 minutes) should be administered following the warm-up and prior to the commencement of the test.
Once the test configuration has been set up, and the test official(s) and the athlete are ready, then the test can begin.
Starting the test
The test should always begin with the athlete’s performing the Static SJ followed by the IMTP, due to the fatiguing nature of the IMTP.
Performing the Static SJ
Performing the IMTP
After completing the Static SJ test, the athlete’s should be provided with sufficient rest time; 3-10 minutes has been used in previous research [5, 6]. For the IMTP, athletes should obtain self-selected knee and hip angles based on the reports of previous research [5, 7] and ensure the barbell sits on the mid-thigh.
The equation below is used to calculate an athlete’s DSI. Although it is often referred to as a “ratio”, it is not displayed as a one, and is instead a simple division between ballistic and dynamic or isometric peak forces.
Dynamic Strength Index (DSI) = Ballistic Peak Force (N) / Dynamic or Isometric Peak Force (N)
Example:
Using only the best performances from the Static SJ and IMTP tests, the following can be calculated. Table 1 displays examples of various DSI scores.
Dynamic Strength Index (DSI) = Static SJ peak force (N) / IMTP peak force (N)
DSI = 1450 / 3178
DSI = 0.46
When conducting the test there are several factors that need to be taken into consideration before you begin – some being:
The Static SJ and IMTP test has been proven to be a reliable measure of maximal and explosive strength capacity in recreational and collegiate athletes [6, 5].
Some coaches believe that reading one article will make them an expert on Performance Testing. Here’s why they’re wrong…
Performance Testing entails many, many topics. By choosing to simply read up on The SJ-IMTP Test and ignore the sea of other crucial Performance Testing topics, you run the risk of being detrimental to your athlete’s success and not realising your full potential.
To make you an expert coach and make your life as easy as possible, we highly suggest you now check out this article on The Vertec Jump Test.
Reference List (click here to open)
Owen Walker MSc*D CSCS
Owen is the founder and director of Science for Sport and chief editor of the monthly Performance Digest. He was formerly the Head of Academy Sports Science and Strength & Conditioning at Cardiff City Football Club, and an interim Sports Scientist for the Welsh FA. He also has a master’s degree in strength and conditioning and is a NSCA certified strength and conditioning coach.
Follow him on Facebook
Learn how to effectively carry out tests on your athletes without spending a penny. You’ll master performance testing, field tests, gym tests and more for free.