For years, strength and conditioning coaches have relied heavily on the Isometric Mid-Shin Pull (MSP) and Isometric Mid-Thigh Pull (IMTP) to assess athletic performance. These tests are widely used because they are highly repeatable, simple to perform on a force plate, and provide valuable information about maximal voluntary force and early neural drive.

However, maximal force and explosiveness are not the same physical quality. When testing explosiveness, the key question is not only how much force an athlete can produce, but how quickly they can generate it during a dynamic movement.

A study published in Sensors by Rosaci, Latini, Nigro, and Bartolomei (2025) highlights an important limitation of isometric testing: a static pull may not fully reflect how an athlete develops explosive force during movement.

By comparing the Isometric Mid-Shin Pull with several vertical jump conditions, the researchers revealed important differences in force development and quadriceps activation. Their findings offer practical insights into how coaches and sport scientists should approach testing explosiveness in athletes.

CONTENTS

1- The Experiment: Static vs. Dynamic Force
2- Key Finding 1: Standing Still Produces Force, but Jumping Reveals Explosiveness
3- Key Finding 2: Explosive Movement Changes Muscle Recruitment
4- Key Finding 3: Small Loading Variations Do Not Change the Overall Blueprint
5- What This Means for Testing Explosiveness
6- FAQ: Testing Explosiveness in Athletes
7- Reference

1- The Experiment: Static vs. Dynamic Force

To explore the difference between static strength and dynamic explosiveness, the researchers tested 15 resistance-trained individuals across five different conditions. Each test was performed on a force plate, while surface electromyography (EMG) measured quadriceps muscle activity.

The five conditions included:

• Isometric Mid-Shin Pull (MSP): a maximum-effort static pull against a fixed barbell positioned 22.5 cm above the floor;
• Countermovement Jump (CMJ): a standard vertical jump performed using body mass;
• Elastic Band-Assisted CMJ (CMJAB): a deloaded jump in which elastic bands pulled the athlete upward and reduced their effective body weight;
• Elastic Band-Resisted CMJ (CMJRB): a jump performed against bands anchored to the floor;
• Weighted Vest CMJ (CMJV): a loaded jump performed while wearing a weighted vest.

When testing explosiveness, the researchers focused on two key mechanical variables:

• Peak Force (PF): the highest force produced during the movement;
• Peak Rate of Force Development (PRFD): how rapidly the athlete reached peak force.

They also measured the excitation of the vastus medialis and vastus lateralis to determine whether static pulling and dynamic jumping produced different neuromuscular responses.

2- Key Finding 1: Standing Still Produces Force, but Jumping Reveals Explosiveness

Unsurprisingly, the Isometric Mid-Shin Pull generated the highest raw Peak Force. When pulling against an immovable bar, athletes have more time to progressively build tension and reach their maximum force capacity.

However, the results were very different for the Peak Rate of Force Development. All jump conditions produced a significantly higher PRFD than the static pull. In other words, jumping required athletes to generate force much faster.

This distinction is important when testing explosiveness. A high Peak Force during an isometric pull does not necessarily indicate that an athlete can produce force rapidly during a dynamic movement.

The researchers also found no significant correlation between the PRFD measured during the MSP and the values recorded during the jumps. An athlete who develops force quickly while performing a static pull may not demonstrate the same ability during an explosive movement involving rapid triple extension.

Isometric testing remains valuable for assessing maximal force capacity. However, these findings suggest that it cannot be used alone to represent an athlete’s dynamic explosiveness.

3- Key Finding 2: Explosive Movement Changes Muscle Recruitment

The surface EMG data provided further insight into why jumping and static pulling produce different mechanical outcomes. The researchers monitored two major quadriceps muscles: the vastus medialis, located on the inner side of the thigh, and the vastus lateralis, located on the outer side.

Although both types of tests activated the quadriceps, vastus lateralis excitation was significantly higher during the jumps than during the Isometric Mid-Shin Pull.

This difference may be explained by the stretch-shortening cycle. A countermovement jump begins with a rapid eccentric lowering phase, immediately followed by a powerful concentric push-off. This sequence allows the neuromuscular system to use pre-activation, stored elastic energy, and rapid motor unit recruitment.

The Isometric Mid-Shin Pull, by contrast, involves force production without movement or a preceding eccentric phase. The nervous system therefore recruits the muscles under very different mechanical and temporal conditions.

When testing explosiveness, muscle activation cannot be assumed to remain consistent across static and dynamic tasks. The selected test should reproduce the type of neuromuscular demand the practitioner wants to evaluate.

4- Key Finding 3: Small Loading Variations Do Not Change the Overall Blueprint

Coaches frequently use weighted vests or elastic bands to modify jump intensity. These methods can increase or decrease the external load, but the study found that they did not significantly change the main characteristics of force development under the tested conditions.

The results showed that:

• assisted, resisted, weighted, and bodyweight jumps produced similar PRFD values;
• quadriceps excitation remained relatively stable across the jump variations;
• adding a weighted vest or elastic resistance did not fundamentally change the neuromuscular characteristics of the jump;
• reducing effective body weight with elastic assistance did not produce a clearly different force-development profile;
• a standard bodyweight CMJ was sufficient to generate high rates of force development.

For practitioners testing explosiveness, this suggests that elaborate loading configurations may not always be necessary. A regular bodyweight jump can provide a simple and effective assessment of dynamic force production.

However, these findings apply specifically to the loads and conditions examined in this study. They do not suggest that assisted or resisted jumps have no value within a broader training program.

5- What This Means for Testing Explosiveness

The results provide several practical takeaways for coaches, sport scientists, and strength and conditioning professionals:

• Separate maximum force from explosive performance: Use the MSP or IMTP to assess maximal isometric strength, but do not assume these results represent an athlete’s dynamic explosiveness.
• Include jump testing: When testing explosiveness, use vertical jumps to assess how rapidly an athlete can produce force during movement.
• Monitor the right metrics: Peak Force indicates maximum force capacity, while PRFD provides information about the speed of force production. Both metrics are valuable, but they answer different questions.
• Keep the protocol simple: A standard bodyweight jump can provide relevant information without requiring weighted vests or complex elastic band configurations.
• Match the test to the sport: Select assessments that reproduce the speed and neuromuscular demands the athlete encounters during training and competition.
• Train the movement, not only the muscle: Static strength exercises can develop force capacity, but explosive sporting actions also require rapid eccentric-concentric transitions and effective use of the stretch-shortening cycle.

6- FAQ: Testing Explosiveness in Athletes

What does testing explosiveness measure?

Testing explosiveness assesses how quickly an athlete can generate force. Metrics such as the Peak Rate of Force Development provide information about rapid force production, while Peak Force reflects the highest level of force generated.

Can an isometric pull measure explosiveness?

An isometric pull can measure maximal force and early force production under static conditions. However, the study found no significant correlation between the PRFD recorded during the Isometric Mid-Shin Pull and the PRFD measured during the jumps. It should therefore not be used alone when testing dynamic explosiveness.

Why are jump tests useful for testing explosiveness?

Jump tests require athletes to produce force rapidly during a dynamic movement. They also involve a fast eccentric phase followed by a concentric push-off, engaging the stretch-shortening cycle.

What is the difference between Peak Force and Peak Rate of Force Development?

Peak Force is the highest force produced during a test. Peak Rate of Force Development reflects how quickly force increases. An athlete can produce high Peak Force without necessarily generating that force rapidly.

Do weighted or resisted jumps produce a higher rate of force development?

In this study, the assisted, resisted, weighted, and bodyweight jumps showed similar force-development characteristics. The small loading variations did not significantly change PRFD or primary quadriceps excitation under the tested conditions.

Should coaches use jumping or isometric pulling?

The choice depends on the quality being assessed. Isometric pulling is useful for measuring maximal force, while jumping is more representative of rapid force production during dynamic movement. When testing explosiveness, practitioners should select a test that reflects the speed and movement demands of the athlete’s sport.

7- Reference

Rosaci, G., Latini, D., Nigro, F., & Bartolomei, S. (2025). Characteristics of Force Development and Muscle Excitation in Resisted and Assisted Jumps in Comparison with the Isometric Mid-Shin Pull. Sensors, 25(3), 975. https://doi.org/10.3390/s25030975