Brian Schiff’s Blog

It has been known for years that increased coefficient of traction can predispose the knee to catastrophic injury.  Hence, the reason we got rid of all the old style astro turf in football stadiums.  But, traction is influenced by the sole architecture of the shoes as well as the playing surface.  Unfortunately, we are not fully aware of how exactly the sole architecture or this increased traction can lead to injury. 

Nike Astro Turf Shoe

Does footwear really matter?  I say YES.  Case in point - I am not a big fan of Nike Shox because they position the ankle in a plantar flexed position, thereby making it so much easier for ankles to roll inward with cutting.  I have seen too many female athletes suffer inversion sprains while running suicides or training in these shoes.  I simply believe the design creates a biomechanical mismatch and elevated risk for ankle sprains.

Now what about traction?  A study in the American Journal of Sports Medicine by J Wannop et al. recently looked at the difference between two shoe designs in a controlled laboratory study.  The tread types of shoes used were either smooth or tread. 

The shoe used in the study was the adidas Response 2+ CPT (smooth shoe) and adidas Response=2(A) (tread shoe).  The traction testing was performed using a robotic testing machine, while the researchers also observed 13 recreational athletes performing 45 degree V cuts in both shoes.  Data was collected using 8 high speed cameras and a force plate.

The results are not shocking.  The highlights are:

• The coefficient of translational traction and peak moment of rotation were both significantly higher in the tread show compared to the smooth shoe.   
• In addition, the high-traction shoe had much higher peak ankle externalrotation moments, peak knee external rotation moments, peak knee adduction moments, and knee adduction angular impulse compared to low-traction shoe.

The findings of the study indicate that the resultant joint loading increased 12% in the ankle (transverse plane) and 13% and 20% in the transverse and frontal planes for the knee.  This increased traction is certainly enough to push the knee into the previously reported mechanical rupture zone.

What we cannot deduce is whether the increases in joint loading is strictly attributable to the higher linear and rotational traction or if there is even a linear relationship between them at all.

You should also note that athletes often choose traction shoes for enhanced performance.  In this study, there was no significant difference in the performance measured between the two groups.  So, we are left to ponder whether we really need higher traction shoes at all.  Future studies will need to address this relationship as preventing knee and ankle injuries just by adjusting footwear seems like a no-brainer if the science supports this.

So, I was meeting with a 14 y/o soccer player referred to me by a physical therapist today who is need of sports performance conditioning (return to play) work after a lateral release.  This talented female athlete suffers from a shallow trochlear groove, thereby making her more prone to patella subluxations.

Such an incident led to two recent surgeries and nearly a year away from the soccer field.  She has returned to soccer, but has been referred to me for prevention and performance work.  I have been thinking about her program, history and all the athletes I have trained in recent memory with knee problems.

I also recall reading an email this weekend from a past intern asking me if there was a single leg training certification out there as she saw me do so much of it at my facility.  These thoughts lead me to my post today.  If you are a jumping, cutting or competitive athlete using your legs to perform, you should absolutely be integrating single leg training into your conditioning programs.

Why, do I say so?  The answer is rather simple in my mind.  The human body is often out of balance.  The brain is so adept at mastering movement, it learns to compensate for even the slightest deficits on one side.  Over time, you end up grooving improper motor patterns and these tend to lead to small imbalances or even overuse issues.

Ever hear about stretch weakness or adaptive shortening?  Maybe you are familiar with the terms overactive and under active muscles?  Regardless, I can assure you that at any given moment, your body may be susceptible to these patterns.

 Through a poper single leg assessment, I see many issues come to light that may otherwise be hidden with two legged squats, lunges, leg press, etc.  Let me go back to the young lady sitting in my office this morning.  She has bilateral shallow trochlear grooves, yet only one knee to date has given way.  Why so?  Will the other one follow suit?

There is no way to definitively predict if her other knee will become problematic.  But, my hunch is there were some single sided imbalances that may have led to her current injury history.  It is now my job to try my best to prevent such an episode on her other knee, as well as make sure she does not have issues on the surgically repaired side.

Anything short of a program heavy on single leg work would be a mistake for her (and many others like her).  You see, we often reinforce imbalances and poor technique with heavy squatting, lunging and dead lifts seen in traditional programs.  I am not oppose dot these lifts - in fact they can be great for strength and power development.

However, we MUST address and correct the single sided imbalances first.  We must also always include some single leg strength work with our athletes to ensure there is no asymmetry developed unknowingly.  Most athletes compete using their own body weight.  We must train in such a way that we foster control, power and mastery of movement with each limb.

This focus and approach will be most helpful in reducing injuries like ankle sprains, ACL tears, muscle strains and common overuse issues in the lower extremity.  So, next time you think about performance training, I want you to consider the importance and relevance of single leg training.  No program is perfect.  But, I will tell you my track record is pretty solid with prevention, performance and return to play training I have done that relies heavily on this approach to conditioning.

Stay tuned as later this week I will unveil my latest DVD as well as review how traction with footwear affects lower limb joint loading.

Well, I have an update on player x.  She saw my preferred soccer/knee orthopedist in town on Wednesday.  He examined her and read the comments I gave to her mother as well.  In summary, he agreed with me that she had patello-femoral pain/inflammation.

He also told the mother she had just gone back to soccer too quickly and never fully regained her quad strength.  He told her if she continued to work around the deficit, she would likely suffer another injury.  This is often the case.  So, at this point the plan of action is to take a one month hiatus from soccer and do formal rehab three times per week.

While this process will be much slower and less active for player x, it probably will be for the best in the long run.  In the short term, she may suffer some loss of fitness, but she needs to focus on strengthening right now.  I will keep you updated on her progress as time goes by.  She will likely return to me for conditioning to transition her safely back to full soccer once therapy winds down.

In the last post, I identified the issue I believed to be going on with player x.  Keep in mind the player returned to  see me the week of 12/15 intially.  The first line of treatment for PF issues in most clinical scenarios involves the following:

1. Rest
2. Ice
3. Stretching (quads, hamstrings, IT band and hip musculature)
4. Straight leg raises
5. Short arc quads (mini-knee extensions from 30-0 degrees if you will on a bolster) although I am not a huge fan of these
6. Mini-squats
7. Calf raises

I advocated relative rest, ice and stretching with my athlete in addition to the following exercises initially:

1. Single leg step-downs (side progressing to front version) in pain free range
2. Single leg stiff legged dead lifts
3. Single leg bent knee floor hamstring bridges
4. Lateral ankle band walks for gluteus medius work
5. Multi-planar lunges in pain free range of motion

She did well with all of the exercises after week one but noted pain with front step-downs and deeper lunges.  On 12/22 I made a significant discovery: she had adopted a compensatory hip strategy to avoid normal knee kinematics with deceleration.  What am I referring to?  I call it a quad avoidance lunge pattern.  She would shift her trunk into extension with foot contact when lunging onto the affected knee as a result of anticipation of pain. (See video clip below as I show a normal lunge pattern, a quad avoidance lunge pattern and the exericse I use to break it)

To help break this cycle, I used an 18 inch box to elevate her unaffected foot and force her into more normal hip flexion on the affected side in a pain free range.  This seemed to work so we added this to the home program using a stair step and eliminated front step-downs altogether, choosing instead to focus on the side step-down in the 40-0 range if you will.  I also added single leg soccer kicks (no ball) forward and in a crossing fashion to work on stability, strength and proprioceptive control.

The athlete returned on 12/31 and seemed to be progressing but still had discomfort with running.  So, I felt she was not ready for full go as of yet.  She also still had discomfort with short and long shuffles moving to the involved side.  At this point, her mom wanted to know what I thought. about practice.

I advised her that player x needed to continue with strengthening 3x/week and try to ease back into jogging as able.  She said the first indoor practice was coming up the week of 1/4.  My thoughts? Indoor soccer fields and PF pain are a bad fit - period.  But, I told her to let her daughter warm-up and do a few drills to get a feel for things.

The verdict?  I got an email on Saturday saying she could not practice due to the same discomfort.  Her next stop is back at the surgeon’s office for a closer look at the knee tomorrow.  I will keep you posted on the diagnosis and treatment as this is an issue that all of us who work with athletes face and struggle with.  Finding the right balance and progression between rest, rehab and return to play is tricky.  So stay tuned for more details.

I have posted on the perils of patello-femoral pain in the past on this blog.  Today, I will share how surgery to fix one knee problem may lead to a new problem.  For privacy reasons, I will refer to my client as player x. 

History: Player x is a 15 y/o healthy female soccer player who suffered a lateral menscus tear in the summer of 2009.  She had arthroscopic repair followed by a brief stint (4-6 weeks) of rehab.  Surgery went well, but she did not regain full extension in rehab (she has about 5 degrees of hyper extension naturally).

Prior to fall high school season, player x came to me for sport reconditioning.  She had obvious quad atrophy (particularly the VMO) and lacked speed and explosiveness.  She worked with me 1-2x/week for 4-6 weeks and made good progress but did note some mild persistent soreness in her knee.

She played the entire fall season without injury/limitation but continued to have the same mild persistent knee pain.  The first week she began club practice (fall high school season had ended), her club coach had the players do a lot of plyometrics.  The exercises did not seem hazardous, but player x immediately had a significant increase in knee pain.

Her mother contacted me and she recently came back in for an assessment.  Ironically enough, her single leg squat and single leg broad jump were within 90% of her uninvolved leg.  However, she had mild swelling, Quad atrophy (about a 1 1/2 inch deficit) and she had significant pain with lateral movement to the side of her involved knee and could not decelerate without pain.

Hmmm…..   So what is the issue here?  After carefully evaluating her and performing functional testing I was able to rule out quadriceps tendinitis.  Her pain occurs primarily at or beneath the superioir and lateral portion of the knee cap at 30-40 degrees of flexion when she is weight-bearing.

I am fairly confident she has patello-femoral joint irritation with excess compression along the lateral facet.  Why?

1. Perhaps the slight extension deficit allowed her to run more on a slightly bent knee (more PF force)
2. Weak VMO is overpowered by the vastus lateralis creating abnormal lateral translation of the patella
3. Pain is worse with deceleration and eccentric strength exercise going past (greater quad pull and patellar compression occurs with these activities)
4. Pain with lateral movement and change of direction suggest lack of proper medial stability and dynamic control of femoral internal rotation which would subject the kneecap to abnormal joint reaction forces especially laterally where her pain is felt
5. No pin point tenderness consistent with soft tissue inflammation

The entire scenario has likely been perpetuated by the volume of training/running in soccer and was then exacerbated by the plyometrics.  She compensated and ignored the mild pain all fall, but the knee finally reached a breaking point with the plyos (keep in mind she did no plyos in the high school fall season).

I see patello-femoral pain all the time in female year-round soccer players.  What is the solution?  Stay tuned as I will share more details about patella balancing training and my corrective exercise program for player x in the next post.