MY LATEST RESEARCH ON ACL INJURIES IN FEMALE ATHLETES

 

I thought I had done 1 of these somewhat recently until I checked back the other day and it was 2022!

There's still a lot of ACL's being done in both men's and women's footy - 19/800 men's + 23/550 women's in 2025 - which by those numbers isn't a great deal of difference really but the hysteria around female ACL's is sometime ridiculous.

No one wants anyone to do an ACL but it's a part of all sports for all genders.

Looking more closely at female ACL's in AFLW, it's a mixed bag from the somewhat limited data I could collect.

• 23 ACL's injuries in 2025
• 13 in games and 10 at training
• 3 in marking contests
• 2 from indirect contact
• 3 from non-contact
• 1 from direct contact
• 3 from neutral actions
• 3 from attacking actions
• 2 from defensive actions

The notes below come from about 15 pages of info I've collected since 2022 with my go-to coach being Jason Avedesian who doesn't seem to be on socials anymore and now is part of the Cleveland Cavaliers in the NBA.

What I've been onboard with for a while and what gets a fair run in these notes is that the physical side of ACL injuries is not the greatest pre-cursor to ACL injuries although it's usually the result after the fact of these injuries, and more needs to be done around the brain, vision and neurocognitive aspects of performance to really get ton top of it

There's a lot here so put your reading glasses on!

CAUSES

• Biomechanical x trunk flexion, lateral trunk flexion, hip flexion, hip adduction, knee abduction moment, knee flexion, knee internal/external rotation, ankle dorsi flexion, ground reaction forces, single leg landing/cutting maneuver, limb symmetry and variability
• Neuromuscular x trunk strength, quad-to-hamstring strength ratio, hip extensors strength and hip abduction strength
• Environmental x surface type, weather conditions, activity duration and sociocultural perception of training
• Neurocognitive x reaction time, working memory, processing speed, visual-spatial attention, impulse control, self-monitoring and dual tasking
• Prior Injury History x ACL, ankle sprain and sports related concussion
• Additional Factors x warm up implementation/compliance, lower extremity balance/proprioception, fatigue, knee laxity/anatomy, shoe design, stress/anxiety
• Divided attention can reduce knee flexion upon initial contact, increased vertical ground reaction forces and reduced stability during landing/cutting

MOMENT WHEN 

• Within the 1st 40 - 60msecs of contact and way before any conscious processing can occur with the visible bad mechanics being from the athlete not having enough time/space
• Reflex time + electro-magnetic delay occurs in 110msecs after contact which passes before substantial force can be produced from the surrounding muscles after loading the ACL
• Athletes can perform any movement safely in controlled conditions but in competition they must process enormous amounts of environmental information and that changes every msec
• Sensorimotor processes during this are anticipation, pattern recognition, visual attention, response to initiation/inhibition, memory retention, kinematic cueing, reaction time, processing speed, working memory, spatial orientation, visual fixation and trajectory estimation which also changes every msec so you need to train small-sided games, oculomotor training, strobe glasses, sensory boards and live agility training
• Decreased visual-spatial attention/delayed processing speed and reaction time/decreased working memory leads to perception action mismatch/timing leas to delayed neuromuscular response and increased tissue load = increased risk for lower extremity injury so modify cognitive/oculomotor risk factors via sensory boards/stroboscopic eyewear/sports specific virtual reality + game representative agility training = decreased lower extremity injury risk
• Anterior tibial translation is probably the primary biomechanical mechanism for ACL injury and maximum knee valgus likely occurs after the ACL tear so focus on quad strength
• Low visual fusion range (the ability to merge images from each eye into a single image) was the strongest internal ACL risk factor meaning non-contact ACL’s are sensorimotor integration deficits
• Upper body contact is highly influential to ACL biomechanics and athletes landing 30 – 40ms earlier on the contralateral limb after upper body contact is the initial time we think ACL injuries actually occur

GAME WHEN 

• Primarily non-contact during single leg deceleration, 40 – 80msecs after contact, unanticipated conditions
• In Rugby 68% come from indirect/non-contact, 72% during off-the-ball actions and 73% in the 1st 40mins of a game
• Action ratios are side stepping x 38%, single leg landing x 31%, deceleration x 31%
• Pressing, tackling, being tackled, regaining balance after kicking and landings are the most frequent patterns
• Are more prevalent early in the game then late in the game
• 44% x non-contact, 44% indirect contact, 12% direct contact
• 47% pressing/tackling, 20% being tackled, 16% regaining balance after kicking, 7% landings, 10% other
• Most frequent inter-segmental positioning at injury frame x ipsilateral trunk tilt (lateral flex) + contralateral rotation (rotation to the same side), abducted hip (same side), dynamic knee valgus (same side), foot planted and externally  rotated (same side)
• Injury timing during matches – 15mins or less x 26%, 15 – 30mins x 19%, 30 – 45mins x 21%, 45 – 60mins x 13%, 60 – 75mins x 12% and 75 – 90mins x 9%
• 33 – 66% of non-contact ACL’s occur during defensive situational patterns x defensive pressing, high horizontal speeds, rapid deceleration, single leg loading, 84% involve neurocognitive error, deceiving action within .240ms prior, high neurocognitive load, knee valgus, extension foot position = horizontal deceleration training
• Non-contact more likely than indirect/direct contact
• More common in defensive actions v attacking actions + more common in out of possession actions v in possession actions
• Injury frequency while pressing/tackling is way higher than other actions
• More common in single leg support moments than 2 leg
• Often involves complex multiplanar interactions with a predominace of knee flexion + a consistent knee valgus pattern at the frame of injury

NON-CONTACT

• Is a sensorimotor integration error where athletes are usually visually distracted while focusing on something that’s not directly in front of them and an error comes in judging when/how much muscular force is required to decelerate
• 50% present with zero valgus but they aren’t caused by valgus and it isn’t a good predictor as it’s probs caused by the ACL tearing, not the other way around
• Biomechanically, 1^st look at the trunk/hip where excessive posterior/lateral shifts can heavily influence knee joint loading
• ACL/valgus are both caused by a lack of foot locking tension/collapse resulting in disorganisation between shin/thigh so train foot locking tension under pressure to produce organised movement
• Many non-contact ACL's might stem from an athlete not being able to properly initiate horizontal deceleration via visual stimulation overload (perception-action mismatch) and thus delayed limb stiffness and rapid ligament loading

TESTING

• Bilateral drops/jumps are not associated with ACL's as they are only ever performed in 1 plane of movement and the bilateral nature also has much greater force that can override unilateral deficiencies and is also a more controlled movement
• Any ACL screening test must include a neurocognitive/dual task component
• Non-contact occurs because of time and space constraints so employ a greater exposure to match-day demands when performing reactive change of direction movements
• Many occur when the athlete is performing a dual cognitive-motor task such as attending to an opposition while changing direction but most rehab exercises are single cognitive
• Drop jump/hop/cutting tasks are the 3 main tests used in rehab so dual task them by also using memory recall during them such as color cards and they recall them in the order you showed them, hold up a picture and they have to recall something from it (object/color etc) or show a shapes slideshow and the athlete has to say what shape preceded the "go" slide

TRAINING

• Extended leg/flat feet landings don’t disperse force over all the leg muscles/joints and are high risk with plantar flexion allowing the calves to lengthen and help attenuate landing forces
• Have your athletes perform cuts under anticipated/unanticipated conditions, film it and look for biomechanical changes at the trunk/knee
• Yes, loading that exceeds tissue tolerance will cause an ACL to tear but there’s so much emphasise on the physical that it’s time to look into sensory input
• There’s a relationship between visuomotor reaction time and non-contact lower extremity injury
• 2 - 3/week x 5 - 10mins do small-sided games/strobe glasses/sensory boards/virtual reality
• For every 10ms decrease in reaction time, there's a 15% increased risk for injury independent of any biomechanical testing
• Think about low arousal conditions = low risk v high arousal conditions = high risk
• Traditional linear learning methods practicing to achieve ideal movement is the least effective treatment but manipulating task constraints enhances athlete robustness
• Use both internal and external focus of attention for ACL risk reduction/rehab but get away from internal as quickly as you can and then the implicit/explicit instruction depends on how much and what type of information is provided as an external foci can be provided both implicit/explicitly 
• Gastroc serves an antagonist for the ACL ligament and the soleus antagonist so train seated calf variations
• Implicit motor learning/random practice/differential learning are concepts that should be integrated when practicing to obtain the most optimal results when learning/fine tuning skills
• A tired neck decreases movement/vision accuracy/precision and the slower you can process what’s around you then the slower you’ll be to react – better vision = more time/space
• ACL injured athletes have worse visual memory than those who aren't and that is correlated with greater time to stabilise = decreased proprioception
• Low vision scores are associated with peak anterior shear forces, peak knee abduction moment/angles and peak valgus during ball handling tasks – all classic pre-cursers to ACL injuries
• Improve the ACL 11/Prep to Play programs by adding in neurocognitive elements such as moving limbs unilaterally, tossing tennis balls against a wall, reacting to partner calls, showing math/pattern cards you look at and then have to repeat back from memory etc – anything to ramp up complexity but not intensity
• When side stepping, keep low to the ground and use small steps
• When decelerating, get your weight on your heels, use tiny steps and get low
• When changing direction keep your feet under base of support, avoid trunk flexion/rotation away from the direction you’re trying to go and face your intended direction