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Hamstring Training and Injury Management in Team Sports, Episode 1: Conversation with Ken Crenshaw

Today i have the pleasure to start an exclusive article/interview series on the topic of hamstrings management in team sport with a bunch of colleagues working worldwide in professional teams in different disciplines (football, baseball, basketball and rugby).

For the first episode of the series i reached out to Ken Crenshaw, one of the key professionals when talking about performance in MLB.

We met a few years ago and we had some interesting discussions about injury prevention methods in pro baseball teams.

Source: Christian Petersen/Getty Images North America

AR: Ken, you've been working with the DBacks for a long time now. Can you explain how your role has evolved over time and how you actually manage all the aspects related to performance and rehab?

Ken Crenshaw: I have fortunately been able to work with 4 different professional baseball organizations (Pittsburgh Pirates, Atlanta Braves, Tampa Bay Rays, Arizona Diamondbacks) all which have helped me get to where I am now. In each organization I had a slightly different job title which allowed to me have a very broad view of how to build a sports medicine & performance team. I started as an athletic trainer and evolved into a strength & conditioning coordinator and then back to an athletic trainer. I have recently had a title change with the Arizona Diamondbacks to Director of Sports Medicine & Performance. I oversee all aspects of our athletic training, rehabilitation and performance (physical & mental) departments. Although I have been doing this for many years I think it allows me an opportunity to fine tune the areas more than I did in the past. I requires a diverse understanding of all areas and demands good communication amongst all areas for the best results. It also allows me to really focus on staff development which I think is critical.

AR: Hamstrings injury seems to have a large impact on MLB. Do you think there is still the need to emphasize hamstrings training over a more comprehensive performance program? What is your approach in off-season and during-season?

Ken Crenshaw: I think just emphasizing hamstring training would be a mistake. We view the body as a whole. Functional movement requires synergy of several components thus all must be addressed. I think the emphasis on the hamstring can happen within a well-rounded approach. The approach we have during the off season is start with recovery both physical/mental, we then would focus on building a solid foundation of cardiovascular function, mobility/stability, strength, power and position. That leads to our skills development time period and then into the pre-season games and regular season games. During the in-season you are trying to maintain your off season gains and possibly build on a few areas. Secondly you are in daily monitor mode for things that may need to be tweaked for best function and recovery. We play 162 games over about a 180 day period so it is critical to stay on top of the small things.

AR: Most performance and rehab professionals doesn't make a proper distinction between training for hamstrings health and training for hamstrings rehab. The different situation in muscle physiology between a previous injured and a non-injured athlete leads to different methods and training variables. How do you manage the rehab process and what baseline testing and metrics you use for return to play decision?

Ken Crenshaw: We have several pre-season screens that we continue to look at daily, this helps us make the necessary adjustments to each player and their program. The distinction between rehab and normal training is somewhat different but also alike in many ways. We focus on proper pelvic/rib cage function as that is what drives hamstring function.

You will obviously have limitations in the amount of stress you can put directly on injured tissue so that has to be gradual and planned. Our regular training program takes into account 3 planes of movement, game demands, previous injury, volume and position that the player plays on the field. As for our baseline testing we do multiple measurements of pelvic position, rib cage position and ability to move in a reciprocal manner. We look at diaphragm position and function. Understanding length tension relationships in all 3 planes of movement drive the interventions we may use to correct aberrant movement patterns. We take into account all joint limitations and also ability to do quality movement before we create a specific player program (rehab or regular). Example would be looking at how the foot may effect the hip or how the hip may effect the foot/knee etc. We implement the plan and monitor to see how each player is responding and make adjustments based off what we see.

AR: An holistic approach to hamstrings training seems to be supported by some recent researches as well as what we see in daily practice. How important is a proper speed and coordination training into the hamstrings conditioning process?

Ken Crenshaw: We certainly take the holistic approach with our program. Speed and coordination are 2 key things when it comes to proper function. They must be trained but not before the fundamentals of movement and function. Also having planned recovery periods and nutrition/hydration/supplementation adequacy is paramount for success.

AR: Eccentric strength and fascicles length are two fundamental parameters related to the risk of hamstrings injuries. Nordic exercise as well as flywheel eccentric can have their place into a training plan but overemphasizing a single exercise or method is a big problem in professional sport. What is your opinion about the way eccentric exercises are being used today?

Ken Crenshaw: As I said previously you need to look at pelvic position & function. If the pelvis is not in good position or tensioned wrong then there will naturally be more stress on the hamstring group. The eccentric training is important but not a stand-alone exercise. I think to focus just on eccentric hamstring strength may be ill advised.

Focus on core stability/function and rib cage position or posture in general as that will lead to a more comprehensive approach. That is not to say eccentric hamstring strength & control are not important as they are but having a broader approach will give best function. Many times loosening tissue (fascia etc) that may be limiting (antagonisticly) hamstring function will be a great addition to eccentric strength.

AR: Technology application is growing today and professional teams are starting to invest in high-end equipments to best assist the health of the players. Neuromuscular diagnostics systems as well as eccentric strength asymmetry testing are growing in popularity both in USA and Europe. What is your approach to monitoring hamstrings condition during the season?

Ken Crenshaw: That is a very complicated question and not an easy one to quantify or answer. Knowing that each player has adequate pelvic/rib cage position or ability to reciprocally move is our base. Having adequate eccentric strength bilaterally is important. Having proper hydration/nutrition balance is critical. Knowing what type of response our training or game schedule is doing to a players nervous system is something that we monitor. Assessing and adjusting a players game/practice volume is a must. There are a number of diagnostic tools but you must have interventions for anything you find thus I would say you need to quantify what you think is the most critical thing and work down the list from there.

AR: The last topic i want to address is the difference between weight-bearing and non weight-bearing exercises for hamstrings function. Muscle activation as well as timing and coordination are highly influenced by foot strike dynamics and overall foot/ankle function: what is your opinion about the ratio between weigh-bearing and non weight-bearing hamstrings exercises in a specific training program?

Ken Crenshaw: I think both are important as we always look at muscles as 2 way streets. Depending on the demands of the movement you can set up training based off that. Ultimately most sports are played on your feet so you have to incorporate weight bearing exercises. We do many activation exercises non–weight bearing to help the athlete find and feel specific muscle firing patterns prior to weight bearing. This also may help in inhibiting a chain of muscles which is important in our philosophy. As for the ratio I think it will depend on what the athlete can qualitatively do which will allow progression or regression in your training or activation program. Lastly it is critical to have a return to play progression with movement sequences which will incorporate open/closed chain exercises in concentric/eccentric ways. Running technique improvement can aide in decreasing movement stress thus is a big part of our preventative programming and also rehab programming.


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