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By Carl Valle
The isometric mid-thigh pull (IMTP) is a specific strength test that assesses maximal strength and rate of force development (RFD) for athletes. Now that international sport science is more accessible, the U.S. is gravitating to the assessment due to both the rise of force plate usage and the need to get more useful data with athletes.
In this article, I explain how to do the test, why it matters, and how to interpret the information. In addition to the test itself, I dive into the interaction of the test’s metrics with other assessments. The IMTP is a wonderful option for evaluating an athlete’s ability, and the information is worth the dedication of time and effort.
What Is the Isometric Mid-Thigh Pull?
The IMTP is a maximal strength test done with force analysis hardware and a barbell placed equidistant between the athlete’s knee and hip. Similar to a clean or deadlift, the exercise is isometric in nature, meaning the bar doesn’t move because it’s locked in place. The athlete needs to pull with their legs into the ground, and put an all-out effort into pulling the bar vertically to estimate their raw leg strength.The #IMTP test is a simpler and safer option than the traditional one-rep maximum test, says @spikesonly. Click To Tweet
The IMTP is simple and safe to do, so many teams and coaches use the test to estimate the maximal strength of athletes. Because of the risks associated with maximal strength testing that uses conventional barbells, some teams have all but eliminated the traditional one rep maximum (1RM) test from their battery of assessments. The IMTP is a great replacement.
One primary reason coaches have not used the IMTP more often is that it requires either a force plate or strain gauge to properly acquire force and time data from the assessment. Only a handful of teams and schools had access to force plates years ago, so the test was considered something only for elite clubs or sport scientists. Now that force plates are common and affordable, performance of the test has grown internationally, especially in the U.S., where we use dynamic strength tests.
Again, the IMTP is an isometric test, so the voluntary output provided by the athlete is expected to be an honest effort. While any volitional exercise is at risk of poor compliance with both technique and effort, the IMTP solves this problem because the technical demand is minor and leading force analysis systems give immediate feedback. Along with baseline data, normative scores that add perspective to testing can help drive better commitment to maximal performance. The only fault with isometric testing is that, without biofeedback, sometimes athletes are not motivated to give their best effort, but a competitive environment should solve this potential problem.
The Key Three Benefits of the Isometric Mid-Thigh Pull
I shared the value of the IMTP earlier, as a test that is safe and easy to perform, and provides useful information in a great package. The exciting part of what looks like a vanilla test is that it’s team-friendly and very practical when time is a factor. A few seconds of effort is all you need to get an athlete tested, so you can assess entire rosters in a few minutes. In fact, progressive teams have constructed dedicated stations to make the IMTP more efficient, which is evidence of the value of this one test.The #IMTP test only takes a few seconds of effort, so you can assess entire rosters in just minutes, says @spikesonly. Click To Tweet
Personally, I have always found the idea of using the IMTP intriguing, but the price tag of force plates and cumbersome software spooked me from committing to it. When I heard about a solution that would streamline testing and be affordable, I circled back to see what we can do beyond just testing quarterly. To boil down the essence of the IMTP in detail, here are the three key reasons coaches should add it to their testing arsenal.
- The test is valid and represents exactly what it measures.
- Safety is virtually a non-issue, unlike many maximal strength tests.
- Using the IMTP in team environments is both practical and time-efficient.
These benefits are rather straightforward and don’t need much expansion or detail, but they are worth elaborating on because you can make an argument for other tests. All three listed benefits work together to form a great testing solution; without all the pieces working together, the test would be just another regular option.
If I was to sell the test, my main case for it would be the fact it’s the best training assessment for team sports environments that find it difficult to test strength of the lower body. While I do like maximal effort appraisal options like squatting, the risk and residual fatigue afterwards is a burden that just isn’t worth it anymore. I am a fan of maximal strength and train for it, but testing it has risk and baggage afterwards. Since the sequence of testing usually has the slower maximal strength lifts later in the testing battery, the total cumulative fatigue is sometimes too much during congested schedules in the preseason or regular season. Even though the test is a maximal strength assessment, it’s isometric, so the residual soreness and fatigue associated with intense assessment is lower than with counterpart barbell tests.
I stopped doing max tests only a few years ago, as the information I got with load velocity modeling was enough to fit a very accurate approximation, but the IMTP is great for athletes with poor lifting track records, especially in soccer, baseball, and basketball. The IMTP may not be a replacement for everyone, but it’s safe to say it can be for many coaches who simply want to gauge maximal strength but only train near-maximal.
How Does Sport Science Support IMTP?
Before we talk about validity, reliability, precision, and accuracy, the most important question is the value of the test. Validity is often thought of as measuring a test’s usefulness, but validity only points out if the test actually measures what it’s supposed to measure. The IMPT is both valuable—meaning it’s effective in helping athletes—and valid in providing information that represents a true measure.
Isometric readings of strength are not perfect in demonstrating transfer to performance, but they are solid enough to merit having the isometric mid-thigh pull be part of the best testing options for coaches and sport scientists. Based on the available evidence, the IMTP has value as both a test and a correlate to show it connects to actual performance. Remember that performance is a mix of various qualities rolled up into one, so talent identification in a complex world of sport can’t be distilled to just one strength test.
Validity: Isometric tests are valid enough to warrant their use in strength and conditioning, but they don’t predict what an athlete can do in other strength tests. Two types of validity exist, criterion and construct validity. To most strength coaches, criterion and construct validity go one step farther than they feel comfortable. Usually, coaches stop at the notion of a test living up the “expectations” of the claim.
For example, a squat jump measures the qualities of jumping from a static position, but some people forget this and assume that a high jump means great athleticism, and several great jumpers are very average in sprinting. Isometric mid-thigh pulls, whether in a fixed or portable system, do a great job of joint-specific pulling, but thinking they are perfect for maximal leg strength dynamically is a stretch—they’re in the ballpark. Technically, maximal strength, whether concentric or eccentric, is specific to the exercise and considered more meaningful because it’s dynamic, but it’s still not a gold standard.
Reliability: The reliability of the IMTP is very good for several reasons, and the most obvious one is that the athletes tested can replicate the same motion simply by following directions and using the same equipment over and over. Due to the low level of skill needed, athletes can see their trends improve from actual changes in maximal strength, not from becoming better at the test.
While the isometric squat is an option, the IMTP is a viable alternative because it’s easier to set up. Some athletes not familiar with strength training may see a rise in scores from learning to express their nervous systems better, but a well-rounded training program should solve for that potential issue. Provided that those involved follow the protocol and the athletes are equally as motivated and committed to expressing their maximal effort, the test is reliable.
Precision and Accuracy: The instrumentation of most systems, such as force plates and strain gauges, provides excellent precision and accuracy, down to the kilogram and single newton. Perhaps the IMTP’s leading benefit is that the instrumentation is sensitive enough to see changes over short periods of time (weeks) and the accuracy is almost exactly what the computer screen claims. The single-strain gauges are precise, but their accuracy is not the same, which means the data is not interchangeable with other systems and force plates. Overall, the sports technology market is strong on the hardware, but software is more variable because it’s sometimes seen as an afterthought.
RFD: The rate of force for a strength test has some connection to sport, but remember that the time to peak force takes much longer than an entire foot strike in running and cutting. The RFD scores are worth noting, but it’s important that coaches realize the dynamic strength index (also called the explosive strength deficit) may fit their needs as well, as those that use force plates are likely to also test jumping.
RFD testing during the IMTP looks at how quickly general total body strength creates speed, while the dynamic strength index looks at the relationship between rapid power of jumps and maximal absolute force qualities of the pulls. Rates of ballistic force are highly coveted and precious in sport, and the RFD of the IMTP is a clue to overall development, but so far no RFD scores for the IMTP connect to RFD of maximal speed.
Correlates to Performance: Studies have found that if you are a high performer in maximal force with the IMTP, you will likely do well in strength and speed activities. Global strength is a main driver of performance, but it’s not magic, as it requires skill and specific training. Research on speed and even change of direction found that athletes who performed better in those field tests or events scored high on the IMTP.
Obviously, dynamic and more-specific tests will connect better, but the IMTP is popular because it helps look at capacity to perform rather than replicating tests or events. No coach worth their salt will train to score high on the IMTP so athletes can run faster. Coaches simply want to know if strength is holding back a fast athlete who may benefit from a better strength base. Sometimes athletes need to stay on the same track and work on the speed component of the F-V curve.Will you complement or replace your existing strength assessment program with the #IMTP test? Click To Tweet
As you can see, a lot of research already exists for the IMTP and it’s clear that confidence in having it in a program is not foolish. Most coaches will decide if they want to complement their existing strength testing program with the IMTP or replace traditional testing with the assessment. I am a fan of keeping both and I use each test, but I like to test 1RM with velocity readings and displacement to reduce the risk of pushing too hard. Usually, training data with maximal strength testing—whether barbell dynamic or barbell isometric—are strong-enough clues that improvement is happening; the additional testing confirms it to make strong decisions later.
Setting for Assessment and Performing the Test
Testing an athlete doesn’t require much and, if primed well, one test done properly on the first try is usually enough to get great information. Exercise familiarization, or the process of an athlete learning how to do an exercise properly in order to extract true value from a test, is the reason many early tests are not valid or accurate measures. In general, the more complicated a movement, the more learning required to properly execute it. The IMTP is an isometric action that requires very little explanation, and since the exercise requires no temporal or mechanical follow-through besides pulling hard and fast for a brief period, the minimal amount of briefing and instruction streamlines the process.
Most of the setup of the IMTP consists of combining the force plates and the bar placement from the knee to the hip, as that is the core of the test. When investing in the test, coaches have two options:
- Dedicated station with a strain gauge or force plate(s)
- Temporary solution with a rack with a strain gauge or force plates
Facilities that use the test repeatedly with multiple teams over the season, like colleges and high schools, should think about creating a rig or buying a workstation. While it may take only a few minutes to set up, specialized equipment is still faster and more convenient due to the equipment being permanently mounted or assigned.
Before explaining the specific body mechanics of the lift, you must instruct the athlete to commit to a full five seconds and come back and try to perform better after a few minutes of rest. In my experience, a modern athlete who is new to the test can be all over the place with output, as isometrics are less common now than they were in the ’50s and ’60s. While some coaches may employ isometrics with bracing movements or split style options, you are more likely to see a dynamic style lift like a power clean than rounds of bilateral isometric exercises.
Performing the IMTP properly requires a coach who knows the power position of the Olympic lifts, as too many athletes assume the exercise is a finish of a deadlift or rack pull. A good IMTP position is the location where the weight hits rapid acceleration when the bar passes the knees, and this may not be the same with everyone. The middle point of the thigh is a great starting point, but experienced testers will want to make sure body structure does not create confusion for the exact positioning of the bar. Have the athlete keep their torso relatively straight vertically and use a minimal knee bend, but make sure it’s comfortable or they will not pull with a maximal effort. Injury history with older athletes is sometimes an issue, but for the most part, the test is safer than conventional 1 rep max testing.
Having the athlete pulling at hip width apart and with arms straight is of vital importance, as a change in grip and body positioning will change the results and make repeatability difficult. Speaking of grip, participants may want to use wraps, as leg strength and hand strength are not connected. Several talented jumping athletes have explosive legs, but the grip on a lift like the IMTP will limit the expression of those gifts.
Now comes the lift. When the athlete is ready to pull, they need to pull hard and fast. An athlete who knows that they have five seconds to work with may think they have a lot of time to ramp up efforts incrementally, but the truth is they need to be beyond urgent to express their strength. The rate of force, whether time intervals or the duration it takes to reach peak force, requires an athlete honestly racing to their maximal strength output, and those metrics are great for seeing change, provided the athlete follows protocol.
If an athlete is confident they have done their job, there is no need for a repeated effort. After they record a personal best as either a baseline or all-time highest score, the comparison will have a number to chase in the future. Sometimes you’ll need a few tests, but most of the time one to two tests are enough, especially with experienced athletes.
The last need of the IMTP protocol is what America does best—create a supportive and motivating environment. While other countries may have taught a few things to the U.S. in regard to sport science, that advantage shrunk and is likely no longer a real advantage due to the globalization of high performance. The United States’ secret weapon is competition and the belief that anyone has a chance of making it, and that level of drive is what you need on test day. Watch any YouTube video of college testing and you may think we are back in the days of gladiators or medieval jousting. A maximal effort with feedback is an amazing display of how adrenaline can turn a walk-on into the next monster of their sport.
Interpreting the Data and Using the Information for Training
After the data comes in, the next step is to interpret the data and apply the information to a training program, if necessary. For the most part, the IMTP doesn’t produce anything extraordinary or revealing, it just confirms or denies the preparation and possible trend of a training program. Don’t confuse straightforward information as being worthless; in fact, the direct nature of the data is the reason coaches and sport scientists love performing the test, as it’s not fuzzy or cloudy. How much maximal force an athlete can pull with their body is not hard to interpret, and the way they develop their force (rate of force) is also easy to analyze.
When looking at the data, it’s wise to step back and see the big picture first, way before you start reacting to the information. The IMTP only provides a few puzzle pieces to the story of how an athlete can express strength, so one test isn’t going to dictate all of the decision-making later. On the other hand, dismissing the test if the information isn’t positive is a big mistake, as you shouldn’t view the quality of information as merely nice to know and not impacting the health and performance of the athlete tested. Tracking peak force characteristics of an athlete in a repeatable way is undeniable truth, and acting on it appropriately is a responsibility of both the coach and athlete. The goal of testing is to see where talent levels change from training, not to serve as a way to scout for future stars.
Four essential metrics are priorities for the IMTP test. The primary measure is peak force. Another is the symmetry between the right and left legs when you use dual force plates. Some systems use a single-strain sensor or single plate, but it’s standard to compare bilateral force data. The third metric is the rate of force development, a measurement that I outlined previously in my article on how it matters in sport, and a full breakdown of the science and application of RFD. The last measure is the relationship between peak values and ballistic motions like countermovement jumps and sometimes static jumps.
The dynamic strength index is a composite metric, hinted at earlier in the science portion of this article. I purposely left it alone because I only wanted to mention it as a definition, and it’s better explained in the training design section here.
Peak Force Measures: Unlike jumps and other explosive metrics, peak values have more usefulness with isometric pulling because they are likely better representatives of an athlete’s accomplishments. Maximal force or peak force is a snapshot in time for a jump, but in a pulling session they correlate better to summarize what an athlete can do with strength.
Asymmetry: While having asymmetry is normal, the extent of it is subject to the clinical experience of sports medicine and the expertise of the coach. Sometimes athletes just pull with an asymmetrical style, but this is rare with something as straightforward as the IMTP. The way the symmetry trends and widens/closes is a better indication of what is happening.
Rate of Force Development: A well-executed IMTP can estimate meaningful changes in RFD with intermediate athletes or those with dramatic changes in training in later stages of development. RFD calculations are the most scrutinized metrics in force analysis, as a single slice of time or shape of a curve can’t fully tell the story and requires additional data to see if there are impactful or significant measures.
Dynamic Strength Index: Research on the relationship between jumping tests and the IMTP is increasing in popularity, likely because it combines two important measures. Coaches and sport scientists hope to tease out how athletes utilize their absolute strength in short time frames. While a jump is a rapid movement, RFD during ultra-short time frames like foot strike at maximal speed is perhaps more valuable, but also less influenced by training, as it has a high genetic and anatomical component.
Coaches often have two concerns: How the IMTP changes over a career and how it waxes and wanes over a competitive season. Like most biomotor qualities, athlete characteristics are not easily mapped out, nor do they fall into place neatly, so much of the process is trial and error.
Applying this information is not rocket science, simply because the clarity of the measures strikes to the heart of what holds an athlete back or helps them succeed. While many measures are important in sports training, simple strength indices remove debate and confusion, and directly tell the professional reading the data what is needed in the near future. Repeated testing shows whether a plan worked, whether it needs more time, or whether it makes sense to try something else. Like most qualities in sport, general patterns of growth and improvement come from investing time in training, but no guarantee exists for transfer if a small set of characteristics trend well.
Is the Isometric Mid-Thigh Pull the Right Test for You?
Besides the equipment demands, the IMTP is a test everyone can implement into a training program. The question is not so much about the test, but the ability to implement interventions if you don’t have a say in the training and load management of the athletes. Most teams and facilities will see the strength test as something that removes the fear and headaches of getting useful data from athletes, though.The #IMTP delivers as a reliable, quick, and easy method to assess #MaximalStrength, says @spikesonly. Click To Tweet
Strength is a pillar quality in injury reduction and athletic performance production. Coaches thirst for the ability to assess maximal strength with a reliable method that is also quick and easy, and the IMTP delivers. I personally recommend it, as it provides great information with no regrets later. The IMTP is the perfect solution for coaches in tight spots, such as professional and college settings, and even high school and youth levels.