Practical Uses for the Dynamic Strength Index

This article covers everything you need to know about the Dynamic Strength Index (DSI). Let’s dive right into it!

Coach Travis Mash

Content menu:

• What is the Dynamic Strength Index?
• Why is the Dynamic Strength Index important?
• How to test your Dynamic Strength Index
  – The DSI Formula
• Dynamic Strength Index workout: how to improve DSI
• DSI vs RSI vs Force Velocity Profile
• Dynamic Strength vs Static Strength
• Conclusion

Introduction to Dynamic Strength Index

The Dynamic Strength Index (DSI) is a way to measure an athlete’s absolute strength or maximal strength in relation to their explosive strength. Coaches use this to determine whether an athlete should focus on getting stronger or more explosive.

The DSI can be used to determine this measure with the upper body and the lower body. When matched with the Reactive Strength Index, a Force-Velocity Profile, and a movement screen, a coach or sports scientist will have enough data to individualize a program in a way that an athlete could really benefit.

Prefer to learn more about DSI via video? Check this out:

What is the Dynamic Strength Index?

The Dynamic Strength Index, or explosive strength index, is a measure of an athlete’s maximal strength in relation to their explosive strength. More specifically, DSI is a ratio between an athlete’s ability to produce peak force in an explosive movement in relation to their peak force in a dynamic or isometric absolute strength movement. 

Most coaches use a counter movement jump (CMJ) to measure peak force in an explosive movement. For the maximal strength movement they normally use a 1RM back squat or an Isometric Mid-Thigh Pull (IMTP).

However, with a GymAware RS or FLEX unit, you could use any strength movement as long as you have enough people on your team to compare athletes against each other.

We’ve been using the trap bar deadlift for the max strength portion with our athletes at Rise Sport Performance where I am now the Head of Sports Science. I will explain all of this in later sections. The trap bar deadlift is just a safer way of performing the test.

In practical terms, the DSI is a way of calculating an athlete’s ability to create maximum force in relation to their ability to use that force athletically on the field of play, where it counts the most. 

Later, I will explain how three simple tests available with a GymAware RS or FLEX can give coaches enough information to individualize programming in a way that could be done simply even with bigger groups. I believe that this is the direction that strength and conditioning is heading.

Why is the Dynamic Strength Index Important?

In the world of athletics, strength is only as good as it can be applied to the sport being played. The Dynamic Strength Index is important, because it shows an athlete’s ability to produce force during a ballistic movement like the counter movement jump. This is then compared against the force production in a maximal strength exercise. 

Once a coach gets the DSI report, they know if the athlete needs to focus on heavy strength training, ballistic movements like bounding plyometrics, or a bit of both.

Whether you are a coach, athlete, or parent of an athlete, it’s important to understand the importance of both components: maximum/ absolute strength and ballistic/ explosive strength.

Absolute strength is clearly linked to sprint speed, change of direction, jumping, and almost any athletic endeavor that you can think of. Absolute strength is also linked to allowing young athletes to express their athleticism sooner in their careers allowing them to gain advantage over their competitors and allows them to express those qualities to a greater extent.

Additionally, Dr. Avery Faigenbaum’s research shows clear links of resistance training to a reduced risk of injury.

Absolute strength or maximum force production is one of the requirements for an athlete to produce power, which is what all of us are after. Dr. Bryan Mann, in his work, has explained the importance of absolute strength especially in the first two years of an athlete’s resistance training because an increase in absolute strength was directly related to an increase in all qualities of strength.

However, eventually in an athlete’s career, if an athlete keeps focusing solely on improving his or her 1RM, there will be clear adaptations that don’t necessarily lead to improved explosive strength. Explosive movements like jumping, cutting, and sprinting require athletes to produce force at very high rates. At this point, a lot of factors come into play like the stretch reflex, elasticity, and pennation angle to ensure each athlete is capable of producing ballistic or explosive peak force.

Simply put, if an athlete gets stronger in his or her 1-repetition maximum strength, the athlete would also improve their ability to produce force quickly. That’s why a lot of high school coaches notice that when an athlete gets stronger, they also get faster and jump higher.

Sport is all about producing force quickly, and that’s where the DSI comes in. The ground contact time for a sprint is around 80-90ms, and the swing of a baseball bat is happening at 70 miles per hour or for all of you VBT fans 31.3m/s. 

The DSI tells us if you need strength or speed to become the athlete you dream of. 

How to test your Dynamic Strength Index

Now that we understand the importance of knowing your DSI, it’s time to test. Here are 4 simple steps you need to take when measuring your Dynamic Strength Index:

1. Decide which exercise combination you want to use
2. Measure the peak force of the exercise, using a VBT device like GymAware RS
3. Calculate the DSI, using the Dynamic Strength Index formula
4. Apply the test result in training

Let’s dive a little deeper into these 4 steps.

Step 1: pick your DSI exercise combination

To calculate the DSI, you need a combination of an explosive movement and a strength movement. Let’s focus on lower body movements, while keeping in mind you could do the same for upper body movements.

Explosive exercise

The counter-movement jump (CMJ) is often used for the ballistic explosive movement. You could also use a concentric only squat jump.

Strength exercise

The strength exercise can be an isometric exercise (no change to a muscle’s length) or a dynamic exercise (movement containing concentric and eccentric muscle contractions).

The Isometric Mid-Thigh Pull (IMTP) is the standard option for an isometric strength movement.

The back squat is traditionally used for the dynamic strength movement, but you could also use a trap bar deadlift (TBDL) or any other multi-joint dynamic strength movement.

Exercise combinations: static performance

If you want to compare an athlete’s ability to produce peak force from a static position, it makes sense to compare the trap bar deadlift or IMTP (strength) with a static squat jump (explosive). That way you will find an athlete’s ability to produce peak force without a stretch-shortening cycle (SSC).

For example, if you are training sprinters or football players trying to improve their start in the 40-yd dash, these movements would give you a clear look at their peak force production without the benefit of SSC. 

Exercise combinations: dynamic performance

If you want to compare an athlete’s ability to produce peak force during a stretch-shortening cycle, it makes sense to pair dynamic movements requiring an SSC. For instance by combining a back squat (strength) with a countermovement jump (explosive).

An athlete may have the ability to produce peak force from a static position, but unless they have coordinated neuromuscular systems at the joints being used, their dynamic performance may need improvement. I have witnessed this in my own research.

Calculating a DSI score in each way would give a coach a clearer picture of the athlete being tested.

Step 2: measure peak force

This step is pretty straightforward if you have a velocity based training (VBT) device, like the GymAware RS or FLEX. Simply attach the device to the barbell and look at the peak force produced during the strength- and explosive movement.

Here’s how to measure your (countermovement) jump, using a VBT device.

Step 3: Calculate the Dynamic Strength Index

The DSI is calculated by first measuring the peak force in a ballistic (explosive) movement and then measuring the peak force in a dynamic or isometric strength movement. You can then use the DSI formula.

The DSI Formula

Here’s the formula for the Dynamic Strength Index.

Dynamic Strength Index (DSI) = Ballistic Peak Force ÷ Dynamic or Isometric Peak Force

An example:

Peak Force for a Countermovement Jump (CMJ) = 2,620N

Peak Force for an Isometric Mid-Thigh Pull (IMTP) = 3300N

DSI = 2620/3300 = 0.79

Step 4: apply DSI test results in training (use case)

Coach Joe Kenn, NSCA Coach of the Year several times and Veteran NFL Head Strength Coach, is a mentor of mine. He has always said that testing and technology as a whole is only as good as the coach putting the information to work. If there is no action with the test results, you’re not accomplishing a whole lot. 

So now that you know your DSI, here’s what to do with it. (Suchomel et al. 2020) provides us with some training parameters based on the DSI results. 

With my athlete Ryan Grimsland, I wanted to look at his ability to produce peak force in relation to an SSC occurring. I used a back squat with a CMJ, performed on the GymAware RS. Here’s an example:

Ryan Grimsland performed a maximum squat with a peak force of 6,085.44N and a CMJ at a peak force of 3,933.63N, so his DSI would look like this:

DSI= 3,933.63N/6,085.44N = 0.65

Based on the recommendations above, he would need to focus on ballistic training and maximal strength concurrently, which is exactly where you want an Olympic hopeful weightlifter to be. 

There are so many weightlifters in the country that should perform this test. I watch so many of these athletes pushing their maximum squats, when they are obviously moving slowly performing the competition lifts. That means they are clearly not using their peak force capabilities, so they are wasting their time continuing to push the squat. 

Dynamic Strength Index workout: how to improve DSI 

The DSI allows you to create a base workout with a few changes to accommodate an athlete’s needs. Let’s look at a very simple example:

Base Program for DSI Score (0.6-0.8)

If your Dynamic Strength Index is “low”, then you can increase it with ballistic training and plyometrics. You could aim for relatively high velocity targets during your strength training. For example:

Plyometrics for the Day:

Box Jumps 3×5 at 80% of Max Height

Strength for the Day:

Front Squat 5×5 at 70% or preferably 0.7m/s, when using velocity based training

Deadlift 5×3 at 82.5% or 0.37-0.4m/s

Program for DSI Score (<0.6)

If your Dynamic Strength Index is “average”, then you can continue working on both explosive- and strength performance gains. For example:

Plyometrics for the Day:

5 Hurdle Hops x 5 sets with a focus on max height and minimum ground contact

Strength for the Day:

Front Squat with Bands  3×5 at a velocity of 0.75m/s+

Deadlift with Bands 4×2 at a Velocity of 0.5m/s+

Program for DSI Score (>0.8)

If your Dynamic Strength Index is “high”, then you can focus on maximal strength training. You can do this by training in low velocity training zones. For instance:

Plyometrics for the Day:

Box Jumps 3×3 at 80% of Max Height

Strength for the Day:

Front Squat 5-Repetition Max at 0.45m/s (around 85%), and three drop sets of 5-reps at -10% for max velocity.

Deadlift 3RM at 0.3m/s (around 88-90%) and 3×3 at -10% for max velocity.

As you can see, everyone is still performing almost the same movements with just a few changes. However, those changes can make a big difference. Of course I know that most of you perform way more volume than this, but I wanted to give you an idea.

DSI vs RSI vs Force Velocity Profile

I was asked in my latest Q&A, about which three tests I consider most important in an athlete’s assessment. Without a doubt, the Dynamic Strength Index, Reactive Strength Index, and a Force Velocity Profile provide coaches with a solid amount of information to individualize programs at scale. Here is my comparison:

1. The DSI provides information about whether an athlete needs heavy strength training, ballistic exercises, or a bit of both.
2. The RSI provides information about an athlete’s stretch-shortening cycle and elastic capabilities as compared to the athlete’s ability to produce force in a jump. This one looks at ground contact time, so basically this allows a coach to know what kind of ballistic training an athlete might need.
3. The Force Velocity Profile provides information about the quality of strength an athlete needs to focus on.

With this information, a coach could develop a program based on individual needs in a way that would flow together. I know that my friend, Coach Geoff Stanford and the football strength and conditioning staff at the University of Louisville is taking this approach. I am so excited to see the results. 

Dynamic Strength vs Static Strength

To be clear, dynamic strength involves movements that utilize eccentric and concentric contractions, which in turn gain passive force due to the elements of the SSC. These movements would be more specific to jumping and dunking a basketball or changing direction. 

Static strength is a look at a concentric only contraction, so you can think about the start of a 100m sprint or a running back firing out of the back field at the snap of the football. It might be a good idea to perform a Dynamic Strength Index looking at both; static and dynamic force production.

Here’s an article on concentric only training: Adaptations from Concentric Only Training.

Conclusion

I hope that you have a solid understanding of the Dynamic Strength Index. Now that I have been using my GymAware RS and FLEX units to build these tests, I realize it’s a simple test to perform. Hopefully, this will save some money for some of you coaches considering force plates. 

With velocity based training, a coach can build a solid assessment of an athlete that will give them all the information they need to create a program to meet their individual needs. 

If you have any questions about the Dynamic Strength Index or anything sports science related, feel free to email me at Travis@GymAware.com.

You can take a look at all of my articles at:

⇒ GymAware Articles

Video presentation

References

1. Suchomel, TJ., Sole, CJ., Bellon, CR., & Stone, MH. (2020). Dynamic Strength Index: Relationships with common performance variables and contextualization of training recommendations. J Hum Kinet, 74, 59–70.
2. Mann, Bryan & Ivey, Patrick & Sayers, Stephen. (2015). Velocity-Based Training in Football. Strength and Conditioning Journal. 37. 52-57. 10.1519/SSC.0000000000000177. 
3. “An Applied Guide to Velocity-Based Training for Maximal Strength” https://www.sportsmith.co/articles/an-applied-guide-to-velocity-based-training-for-maximal-strength/

Coach Travis Mash

Being a World Champion in powerlifting, Travis competed at a world-class level in Olympic weightlifting and has coached professional Olympic weightlifters alongside Don McCauley and Glenn Pendlay at Team MDUSA. Now Travis coaches the most successful weightlifting team in the USA.