ASH Test Explained: Athletic Shoulder Testing for Sport
- Jo Clubb
- 33 minutes ago
- 8 min read
This post outlines the purpose, protocols and data outcomes of the Athletic Shoulder (ASH) Test.
I've previously explored how shoulder testing often starts with internal and external rotation strength. Quantifying these capacities with a fixed frame dynamometer, such as VALD's ForceFrame, can provide useful information about shoulder strength and particularly the balance of strength when we calculate the ER: IR Shoulder Ratio. It is a valuable part of many shoulder testing profiles.
But many sporting actions do not ask the athlete to produce force with the arm neatly by their side. Throwing, serving, tackling, reaching, bracing and overhead actions often involve long-lever shoulder positions. These are the positions where the athlete needs to express force, stabilise the trunk, and transfer force through the upper body. They are also often the positions where the shoulder is most exposed.
This is where the Athletic Shoulder Test, or ASH test, can add another layer to the shoulder testing profile. Developed by physiotherapist and performance director Dr Ben Ashworth, the ASH test assesses prone, long-lever isometric shoulder strength in three different positions: I, Y and T. It can help practitioners understand how an athlete produces force through the shoulder in positions that may be more relevant to overhead, throwing, contact and return-to-performance contexts.
What Is the ASH Test?
The ASH test is a prone, long-lever, isometric shoulder strength test.
It is commonly performed in three positions:
The ASH-I position, with approximately 180 degrees of shoulder abduction.
The ASH-Y position, with approximately 135 degrees of shoulder abduction.
The ASH-T position, with approximately 90 degrees of shoulder abduction.
These positions should not be treated as interchangeable. Each gives a slightly different perspective on the shoulder and the kinetic chain through the upper body.
A 2025 study led by Ben Ashworth Sports provides a useful example of this in baseball athletes. In that paper, the authors examined maximal isometric shoulder strength and rate of force development (RFD) across the ASH-I, ASH-Y and ASH-T positions. Their rationale was that different shoulder abduction angles may correspond to different demands within throwing actions.
In practical terms, this means the ASH test may provide useful information for overhead and throwing athletes because it assesses force production in longer-lever positions than traditional ER/IR testing. That does not mean the ASH test replaces ER/IR testing. Rather, the two can complement each other.
Short-lever tests can tell us something about isolated rotational strength. Long-lever tests can add insight into force expression and force transfer in positions that may look more like what the athlete has to manage in sport.
A thrower does not only need a strong rotator cuff. They need to transfer force from the lower body, through the trunk, across the shoulder girdle and into the arm. A rugby player reaching into a tackle position does not only need shoulder strength. They also need to control the trunk and scapula while the arm is exposed in a long-lever position.
This is why the ASH test can be useful. It starts to ask slightly different questions:
Can the athlete produce force with the arm away from the body?
Can they stabilise the trunk while expressing force through the shoulder?
Can they access force quickly, not just eventually?
And what strategy do they use when the test becomes challenging?
That last question is important. If we only look at the number on the screen, we may miss the most useful part of the assessment. Take a look at the full video to see Ben discuss the types of compensations to look out for during the test and what they tell us about how the athlete is trying to create stability or produce force in a challenging position.
Setting Up the ASH Test
As with any athlete test, consistency of the testing protocol matters.
The athlete lies face down in a prone position. Their forehead rests on a block or pad to standardise and relax the neck position. The testing arm is placed straight out in the relevant I, Y or T position, with the hand flat on the force plate.
Force plates, such as VALD ForceDecks, are the gold standard for ASH testing because they allow practitioners to assess force-time characteristics such as peak force and rate of force development.
However, not everyone has access to force plates. The test can also be performed using a dynamometer, such as a fixed-frame device like ForceFrame or a handheld dynamometer from the VALD DynaMo range.
One important protocol detail is the position of the non-testing arm.
In the ASH-I position, the non-testing arm is typically placed by the athlete’s side.
In the ASH-Y and ASH-T positions, the non-testing arm should be placed behind the lower back. This limits the athlete’s ability to anchor through the opposite arm and use it to stabilise against the floor.
That detail matters because the Y and T positions are intended to challenge the athlete’s ability to produce and transfer force without simply fixing themselves with the opposite arm.
The athlete should also point their toes towards the floor. Again, the aim is to limit movement and minimise lower-body contribution.
Remember, this is an isometric test. We do not want to see the athlete changing position, shortening the lever, or creating movement to generate a higher score. The start position should look like the finish position. For demonstrations of the videos being conducted, take a look at the earlier YouTube video.
Peak Force and Rate of Force Development
Two of the most useful outputs from the ASH test are peak force and rate of force development.
Peak force tells us how much force the athlete can produce. This can be reported as an absolute value or relative to body mass.
Rate of force development, or RFD, tells us how quickly the athlete can produce force. This may be particularly relevant in sporting actions where the athlete has very limited time to express force.
These qualities are related, but they are not the same. Plus combining them can be illuminating to the athlete's profile.
An athlete may have good peak force but relatively poor RFD. In that case, they have the capacity to produce force, but may struggle to access it quickly. That may lead you towards more explosive upper-body work, where the athlete has to express force quickly.
Conversely, if the athlete has reasonable RFD but lower peak force, the programming emphasis may be different. They may need more work on maximal strength capacity, positional strength, or progressive exposure to higher force outputs in the relevant shoulder positions.
Of course, the ASH test does not tell us exactly what to programme. But it can help us ask better questions.
Is the limitation maximal force capacity?
Is it the ability to access force quickly?
Is it specific to one position?
Is it specific to one side?
Is it actually a strategy issue rather than a strength issue?
This is also why cueing matters. For peak force, the athlete may be asked to build gradually to a maximal effort. For RFD, the cue changes, as the athlete needs to push as fast and hard as possible from the start.
This is similar to the distinction we often discuss with the isometric mid-thigh pull. If the intent of the test changes, the cueing should reflect that.
For this reason, Ben Ashworth has recommended testing peak force and RFD separately in some contexts. A gradual build to maximum may be more appropriate for peak force, while a fast explosive effort is needed for RFD.
Using Normative Data Without Over-Interpreting It
Normative data can be helpful, particularly when practitioners are first getting familiar with a test. The VALD Practitioner’s Guide to Shoulders includes normative ASH test data, which can provide a useful starting point for understanding force outputs across different positions.
In addition, I have seen Ben discuss values around or above 500 N/s as a useful reference point in some elite environments. That can provide context, but I would still be cautious about treating any number as a universal threshold. RFD in particular is more variable, as we've previously explored.
As always, normative data needs context.
A baseball pitcher, swimmer, rugby player, volleyball athlete, tennis player and general gym-based athlete may all have very different shoulder demands. Even within one sport, playing position, training age, limb dominance and injury history can influence the profile.
This is especially important when we think about asymmetry.
In some athletes, such as swimmers, we may expect relatively similar demands across both shoulders. In throwing athletes, we may expect more obvious differences between the dominant and non-dominant side because the sporting demands are inherently asymmetrical.
So rather than asking, “Is this score good or bad?”, I think the more useful question is:
What does this result mean for this athlete, in this position, at this point in time?
Final Takeaways
The ASH test can be a valuable addition to shoulder testing in sport because it assesses long-lever isometric shoulder strength in I, Y and T positions. These positions are not interchangeable. Each provides a slightly different perspective on shoulder strength, force transfer and upper-body strategy, which may be particularly useful for overhead, throwing, contact and return-to-performance athletes.
Peak force and rate of force development can also provide complementary insights. Peak force tells us how much force the athlete can produce, while RFD helps us understand how quickly they can access that force. However, RFD is typically more variable, so it requires careful cueing, familiarisation and interpretation.
As with any athlete test, protocol quality is critical. Head position, arm position, non-testing arm position, hand contact, toe position and overall body strategy can all influence the result.
Most importantly, practitioners need to watch the athlete, not just the screen.
The ASH test should therefore be viewed as one part of a wider shoulder profile, alongside measures such as ER/IR strength, range of motion, symptoms, injury history, lower-body testing profile, and the specific demands of the athlete’s sport.
Used well, it gives practitioners another lens through which to understand shoulder capacity, but like all testing data, its value comes from how it informs better decisions.
Useful Resources
For more detail on shoulder testing options and ASH test normative data, see the VALD Practitioner’s Guide to Shoulders.
For ASH test demonstrations, exercise examples and progressions, see Ben Ashworth’s Athletic Shoulder YouTube channel.
You can also watch the full video version on the Global Performance Insights YouTube channel.
FAQs on the ASH Test
What does the ASH test measure?
The Athletic Shoulder Test (ASH test) is a prone, long-lever isometric shoulder strength test developed by physiotherapist and performance director Ben Ashworth. It can measure peak force, relative peak force and rate of force development. It also provides observational information about how the athlete stabilises and transfers force through the shoulder, trunk and upper body kinetic chain.
What are the ASH-I, ASH-Y and ASH-T positions?
The ASH-I position tests the arm overhead at approximately 180 degrees of shoulder abduction. The ASH-Y position tests the arm at approximately 135 degrees. The ASH-T position tests the arm at approximately 90 degrees.
Can the ASH test be performed without force plates?
Yes. Force plates such as VALD ForceDecks are the gold standard for ASH testing, especially if you want to analyse force-time outputs such as RFD. However, the test can also be performed using fixed-frame or handheld dynamometry, provided the setup is consistent and repeatable.
Should I use peak force or RFD from the ASH test?
Both can be useful. Peak force reflects maximal force capacity, while RFD reflects how quickly the athlete can produce force. They answer different questions, so the most useful interpretation often comes from considering both together.
However, RFD is more sensitive to cueing, intent, familiarisation and technical execution than peak force. This makes it useful, but also more variable. It should be interpreted carefully and ideally tracked over time rather than judged from one isolated test.
What compensation strategies should practitioners look for?
Common compensation strategies include bending the elbow, diving forward through the shoulder, rotating through the pelvis, or kicking the leg into extension or abduction. These strategies may change the meaning of the force output and should be noted during testing.
Is the ASH test only useful for throwing athletes?
No. The ASH test may be particularly relevant for throwing and overhead athletes, but it can also be useful in contact sports, shoulder rehabilitation, and return-to-performance settings where long-lever shoulder force expression matters.
Should the ASH test replace ER/IR testing?
No. The ASH test should complement ER/IR testing rather than replace it. ER/IR testing provides insight into short-lever shoulder strength, while the ASH test adds information about long-lever force expression and force transfer.
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