In-Season Groin Squeeze Force Monitoring: Catching Adductor Injury Risk Before It Becomes a Strain

A center-back walks off the training pitch in week six with a grade 1 adductor strain. The staff pull up his file and there it is, in hindsight: a squeeze score of 224 mmHg from the preseason baseline, then nothing recorded again until the week he got hurt, when a reactive test came back at 179 mmHg. Nobody flagged the drop because nobody was looking for it. The team had a squeeze test; it did not have a habit of running it often enough, against a current comparison point, to catch a slide happening in real time.

That is the gap between screening and monitoring. A preseason squeeze test tells you where an athlete starts. It tells you almost nothing about where he is in week nine, after eight weeks of cutting volume, travel, and missed recovery days. The protocol below treats the squeeze test as a repeated in-season measurement rather than a once-a-year checkbox, with one goal: catching a week-over-week force drop early enough to act on it before it becomes a strain, not after.

Why One Squeeze Test a Year Leaves the Real Risk Window Uncovered

The preseason baseline earns its spot on the calendar because it is easy to schedule when everyone is fresh and already standing around for fitness testing anyway. The problem is timing: preseason strength reflects an athlete arriving into training, not one six weeks into a fixture-congestion stretch with three games in eight days. Adductor strain risk is not flat across a season; it tracks far more closely with recent cutting and change-of-direction exposure than with how strong someone tested in July.

A single number, tested once, cannot separate two very different athletes: one who is simply weaker than his teammates by nature, and one who started strong and has been quietly losing capacity for three weeks under a load he has not adapted to. Both might post the same absolute score in week eight. Only the second is sitting on acute injury risk, and only a repeated measurement, read against his own recent history, tells them apart.

Building a Rolling Baseline Instead of a Single Number

Comparing a week 8 squeeze score against a preseason test run in July is comparing two different physiological states, not tracking change. The fix is a rolling baseline built from the athlete's own in-season data rather than a single distant test.

Run the squeeze test in the first two weeks of full training and average those sessions to set the rolling baseline. From there, recalculate it as a trailing three-session average every time a new test is added, dropping the oldest of the three. This smooths out the normal week-to-week wobble in any single session's number while staying sensitive to a genuine multi-week slide, which a fixed number from July cannot do six months later.

Not every week-to-week dip is real change. Published reliability work on the Copenhagen squeeze protocol shows measurable test-retest noise even with a consistent tester and cuff placement; running that variation through a standard minimal-detectable-change calculation puts the threshold for a genuine longitudinal change closer to 15-20%, wider than the tighter 10-15% band used for same-day side-to-side asymmetry. A single-session bilateral comparison and a week-over-week trend comparison answer different statistical questions, and applying one cutoff to both produces false alarms or missed signal.

The Weekly In-Season Testing Protocol

1. Pick one hip position and stick with it. Use the 0° position (hips extended, knees flexed to about 90°, ankles together) for weekly monitoring. It is the fastest to administer and carries the deepest published reference data; save the 45° and long-lever positions for return-to-play reassessment rather than routine weekly screening.
2. Fix the day and time. Test on the same day of the training week, ideally 24-48 hours after the heaviest cutting session and before the next one, and at a similar time of day. Adductor strength shows a measurable diurnal swing, and testing a fatigued Monday-morning group against a fresh Wednesday-afternoon group manufactures a fake drop.
3. Inflate to a 10 mmHg baseline before the athlete engages, cue a maximal squeeze held for five seconds, and record the peak reading during that window, not the reading at the five-second mark.
4. Run two trials, not three, for weekly monitoring, with 30-45 seconds of rest between them. Weekly testing is about tracking a trend, not chasing a true one-rep max, and the shorter version is what actually survives a full season without staff cutting corners.
5. Log pain reproduction as its own field, separate from the pressure number. A stable or even normal squeeze score paired with reported groin discomfort during the test is still a flag.
6. Record that session's cutting and change-of-direction load alongside the score, even a rough high/medium/low tag. A force drop that coincides with a training load spike reads very differently from the same drop after a light recovery week.

Total time per athlete runs under three minutes once the group has done it a few times, which is the only reason a weekly cadence survives contact with a real coaching staff's schedule.

What the Research Actually Supports

Thorborg and colleagues (2017), publishing the validation work behind the Copenhagen five-second squeeze test in the British Journal of Sports Medicine, established the test as reliable across repeated sessions run by the same tester with consistent equipment. That reliability data is what makes week-to-week tracking possible in the first place, but it carries a limitation worth respecting: their reliability figures describe short-interval test-retest conditions, not the slower physiological drift a squad experiences across a demanding block of fixtures, so the noise band drawn from that data is a floor, not a guarantee, for how much week-to-week variation to expect from a fatigued, traveling roster.

Delahunt, Fitzpatrick, and Blake (2017), following a squad of elite Gaelic football players across a full season in the Journal of Science and Medicine in Sport, found that a low preseason squeeze score combined with a lower self-reported HAGOS Sport and Recreation subscale score was associated with a higher likelihood of an in-season groin injury. The finding matters for this protocol less for the prediction itself and more for a limitation the authors flagged in their own design: the squeeze measurement was a single preseason snapshot, taken months before some of the injuries it was associated with. A single early-season number predicting a distant injury is a real result, but by the authors' own framing it is indirect evidence for exactly the gap a repeated in-season measurement is built to close — nobody in that cohort was retested between the baseline and the injury, so nobody could have caught the more immediate week-over-week decline that plausibly preceded it.

Reading a Weekly Drop: Thresholds and What They Mean

The bands below translate the rolling-baseline comparison into an action, not a diagnosis. They assume a consistent tester, cuff, position, and timing week to week; skip any of those and the noise floor widens past what the bands assume.

Two consecutive smaller drops matter as much as one large one. A 12% fall in week 4 followed by another 12% fall in week 5 against the updated rolling baseline is a real downward trend, even though neither number alone crosses the higher single-week threshold. Treating each week in isolation is one of the more common ways a real decline gets missed until it becomes an injury.

Mistakes That Turn a Monitoring Tool Into Noise

Building the Weekly Habit Into a Real Staff Workflow

A protocol that requires a spreadsheet fight every Monday will not survive October. The version that works fits into whatever session the team already runs on testing day, usually right after warm-up and before the main field session, when the group is already gathered and a two-trial test takes under three minutes per athlete.

Keep four columns per athlete per week: the peak reading, pain reproduction (yes or no, plus location if yes), the rolling 3-session baseline, and the percent change from it. A fifth column for that week's cutting/COD load, even a rough high/medium/low tag, turns a flagged score from a mystery into a question with an obvious first answer. Review flags in a five-minute huddle right after testing rather than a weekly meeting three days later; the value is in acting while there is still time to adjust training before the weekend fixture.

What to Actually Do When an Athlete Gets Flagged

A flag is a prompt to adjust load and retest, not an automatic stand-down. For a borderline flag in the -10% to -15% band, trim unrestricted cutting volume for that training day, keep the athlete in modified drills that limit maximal deceleration angles, and retest in 48-72 hours rather than waiting for the following week's scheduled session. If the retest recovers toward baseline, the athlete continues as normal; if it does not, treat it as a confirmed decline and escalate.

For a confirmed decline past -15% to -20%, or two consecutive borderline weeks, pull the athlete out of unrestricted change-of-direction work and loop in medical staff for a hip and groin screen before returning to full load, even without pain reported. Force output falling before pain shows up is common with adductor strain, not the exception, which is exactly why this protocol catches cases that waiting for reported discomfort will not. When an athlete does report groin tightness alongside a flagged drop, treat the combination as higher-confidence than either signal alone; that pairing is consistently what the research above associates with elevated injury risk, not the isolated number.