Learning to Run: Simple Prevention Strategies for the Novice Runner Thank you all for coming here today. Today I’d like to tell you about work that I’ve done developing and optimizing a new approach for 3D imaging of knee morphology under weight-bearing conditions using a C-arm CT scanner. Michael Fredericson, MD, FACSM Professor and Director PM&R Sports Medicine Director, Stanford RunSafe Program

Objectives To provide practical tips for the novice runner to help prevent running injury and improve performance.

THE 10 TOP FORM RECOMMENDATIONS FOR THE NOVICE RUNNER

#1 Soft Landing with Relaxed Knee Knee stiffness or reduced knee flexion may be associated with tibial stress fractures and certain sub-groups of patients with patellofemoral pain. Dierks et al. Med Sci Sports Exer 2011. Milner et al. Med Sci Sports Exer 2006

#2 Use your Butt Muscles to Push Off Reduced hip extension and pushoff may be observed with compensations that include: Increased lumbar spine extension Bounding Souza R. PM&R Clinics 2015

#3 Slight Lean Forward A small increase in trunk lean (~7 degrees) results in a significant lowering of patellofemoral joint stress. Teng & Powers. J of Orthoped Sports Phys Ther 2014; Teng & Powers. Med Sci Sports Exer 2015

#4 Land With Foot Under Center of Mass Overstriding is associated with: Reaching (hip flexion with knee extension prior to initial contact) Reduced shock attenuation Increased running energetics A recent study by Wille and colleagues21 identified a metric that is closely related to overstriding – the distance from the heel at initial contact to the runners center of mass – is a significant predictor of knee extensor moment (the sagittal plane torque across the knee joint during stance) and braking impulse (an important contributor to shock attenuation and running energetics) during running. Edwards et al. Med Sci Sports Exer 2009; Wille et al. J of Orthoped Sports Phys Ther 2014

#5 Push Forward not Upward Bounding leads to increase float time, often in response to other deficits (e.g. reduced hip extension). Increasing cadence by 10% during running can significantly reduce vertical displacement and overstriding. This variable can become a problem in “bounders”, runners who increase float time, often in response to other deficits (e.g. reduced hip extension). The end result is increased work required by the runner to perform this type of running. It has been found that increasing cadence by 10% during running can significantly reduce vertical displacement of the center of mass.28 The vertical displacement of the center of mass is a very important metric to evaluate in runners. It is easily measured by comparing frames of video from the runner’s highest point during float, to the lowest point during stance (Figure 9). There are inherent errors in measuring this variable, as the actual location of the center of mass is impossible to assess on video. One strategy is to identify a location on the runner’s pelvis and use this as a surrogate for the center of mass. Increased excursion of the center of mass vertically has been found to be predictive of the peak knee extensor moment, the peak vertical ground reaction force, as well as braking impulse during running, all very important variables in running mechanics.21 Wille et al. J of Orthoped Sports Phys Ther 2014; Heiderscheit et al. Med Sci Sports Exerc 2011

#6 Beware of a Crossover Gait A narrow base of support has been linked to tibial stress fractures, iliotibial band syndrome, and several kinematic patterns that have been associated with running injuries, such as excessive hip adduction and over pronation. Meardon et al. Internl Soc of Biomechics in Sports 2012 Brindle et al. Gait & Posture 2014; Meardon et al. J of Biomechanics 2014

#7 Avoid Excessive Pronation Several studies have linked excessive pronation to various running injuries, such as tibial stress fractures, patellofemoral pain, and Achilles tendonopathy. .. Foot pronation in runners is a variable that has received considerable attention over many years.38-41 However, measuring foot pronation on 2D video presents significant challenges. One component of foot pronation that can be evaluated is heel eversion. By placing markers at the top and bottom of the shoe heel counter, evaluation of the vertical relationship of the hindfoot can be easily assessed. It is important to evaluate the peak magnitude of heel eversion (i.e. the relationship of the superior marker to the inferior marker), but also the rate of pronation. Furthermore, it has been suggested that runners with excessive calcaneal eversion be prescribed orthotics44, or higher level of support shoes; however, the effectiveness of these strategies has been questioned, and current evidence is inconclusive. Barton et al. J of Orthoped Sports Phys Ther 2010; Milner et al. J of Orthoped Sports Phys Ther 2010; Silbernagel et al. J of Orthoped Sports Phys Ther 2012

Velocity of Pronation

#8 Maintain a Knee Window Excessive hip adduction, excessive hip internal rotation, and excessive knee valgus have been implicated in running injuries and can impact the knee window. However, the vast majority of recreational runners that fail to demonstrate a normal knee window or lose the window during the gait cycle, associated with the kinematic pattern described above – excessive hip adduction and internal rotation, and knee valgus. While identification of this variable is quite simple, it should be noted that correcting an abnormally “closed” knee window is not as simple.53 There are some limitations to this measurement. It is important for runners to wear shorts or tight-fitted pants so that this variable can be assessed. In runners with excessive soft tissue on the medial aspect of the knee, this measurement can be inaccurate. Finally, swing limb hip adduction can also create the impression of a closed knee window, even in the presence of good hip-knee-ankle alignment. Nonetheless, this measurement can be a valuable component of a biomechanics running evaluation, and several recent studies have found this variable to be modifiable through a variety of methods. Evaluation of the knee window is a simple dichotomous assessment of the presence or absence of a space between the knees at all times of the running cycle, and is a measure of the alignment of the hip, knee, and ankle from a posterior (or anterior) view (Figure 14). The knee window does not need to be large – an excessively large knee window may suggest a varus deformity, an alignment issue that also presents with potential problems. Noehren et al. J. Clinical Biomechanics 2007; Wilson et al. J. Clinical Biomechanics 2008; Herrington et al. The Knee 2014

#9 Stable Hips Pelvic drop contributes to excessive hip adduction, a variable that has been linked to numerous running injuries. This is related to both decreased hip abductor and hip extension strength. Assessing the amount of pelvic drop, or maximum pelvic obliquity during stance phase can be augmented with the application of markers on the posterior superior iliac spines (Figure 15). By comparing stance limb and swing limb marker positions, the amount of pelvic drop can be estimated. A recent study found that a 2D quantitative assessment of this variable demonstrated excellent reliability but was poorly correlated with a 3D measurement of pelvic drop.57 However, the clinical significance of 3D- Noehren et al. J. Clinical Biomechanics 2007; Wilson et al. J. Clinical Biomechanics 2008

#10 Consider a Forefoot Strike Pattern or Change in Cadence One study on competitive collegiate runners suggested that runners with a RFS pattern developed more repetitive overuse injuries when compared to runners with a FFS pattern. And while these finding suggest possible association between foot strike patterns and running injuries, more work is necessary before broad conclusions on foot strike recommendations can be made to modify injury risk. Key phases of running. A) The end of terminal swing is identified as to the foot remains elevated from the treadmill, just prior to initial contact. B) Initial contact is identified as the first frame when the foot hits the ground. C) Loading response is identified as the first frame in which the runner’s weight is being transferred onto the lead leg and is characterized by the presence of shoe deformation.

Foot Strike Patterns One study on competitive collegiate runners suggested that runners with a RFS pattern developed more repetitive overuse injuries when compared to runners with a FFS pattern. However, more work is necessary before broad conclusions on foot strike recommendations can be made to modify injury risk or improved performance. Daoud et al. Med Sci Sports Exerc 2012

Foot Strike Patterns High speed videos showing the footstrike for every entrant in the Women’s 2012 U.S. Olympic Trials 10,000-meter race.

#10 Increase Cadence Increasing cadence by 10% can reduce center of mass vertical excursion, braking impulse, and mechanical energy absorbed at the knee, as well as to decrease peak hip adduction angle and peak hip adduction and internal rotation moments during running. The optimal cadence has been an area of debate, with some suggesting that ~180 steps per minute being ideal. The step rate, or cadence should be evaluated in all runners. This variable is easily measured in a variety of ways. One strategy is to count the number of right heel strikes over a 1-minute period. This number is equivalent to the “stride rate”. Multiplying this number by two will equate to the “step rate”. However, the majority of support for this comes from running economy studies, not studies on injury mechanics.33, 34 While it may be too early to suggest that all runners should run at a specific cadence, it is becoming clear, that cadence is an important biomechanical running variable, and one that can be easily manipulated in runners when appropriate. The optimal cadence has been an area of debate, with some suggesting that ~180 steps per minute being ideal.

Increasing Cadence vs Forefoot Strike Pattern The issue is whether or not runners need a specific protocol of exercises (or how long that protocol should take) before transitioning, because most runners will probably just try to start with too many miles too quickly, and that's likely when injury is going to happen. Most of the runners in my protocol, who were given no time for (or information about) stretching or strengthening before forefoot striking, were feeling soreness in their calves within a couple of minutes of the retraining protocol. The couple of runners who are my friends and completed my protocol were even reporting soreness the day after testing. In comparison, none of my runners expressed any soreness or pain during the increased cadence retraining and trials. Some of them struggled with finding the rhythm to adapt the pattern during the 5 minutes of retraining, but most found this running pattern to be the easiest to learn. While collecting their data overground, they were still allowed to run with the metronome though to try to help them keep the rhythm as much as possible.

Average Loading Rate Running Pattern Average Loading Rate (BW/s) Forefoot Striking 30.8823 Increased Cadence 53.0041 Rearfoot Striking 49.8786 Average Loading Rate I think that it's hard to really claim that forefoot striking is a better strategy after only 5 minutes of retraining. Most of my subjects (aside from a few trail runners or people who had experimented with forefoot striking) were very uncomfortable and reported soreness after forefoot striking. One subject even had to quit early because he thought there was a chance of injuring himself after only trying forefoot striking for about 15 minutes.  I think that if you think that loading rate is the most critical parameter contributing to injury, then forefoot striking is the easiest way to adjust this parameter.  However, for my paper, I'm hoping to look at other parameters that may tell a different story. For example, if you look at peak absolute free moment (which is thought to contribute to torsional tibial stress fractures), there seems to be a trend that forefoot striking is the worst.

Maximum Loading Rate Running Pattern Average Loading Rate (BW/s) Forefoot Striking 46.6835 Increased Cadence 79.4522 Rearfoot Striking 78.4272 Maximum Loading Rate

Peak Absolute Free Moment Running Pattern Peak Free Moment (N-m/BW) Forefoot Striking 10.5458 x10-3 Increased Cadence 9.9167x10-3 Rearfoot Striking 9.3292x10-3 Peak Absolute Free Moment

Donald et al. Army Medical Journal 2013

Typical RunSafe Profiles

Cassie 12-16 Y/O Male or Female Motivation: Starting cross country/track and field. Symptoms: Osgood-Schlatter, shin splints Classic Issues: increased internal hip rotation, decreased hip extension, increased stride length, low arch, valgus heel, mild overpronation Key Recommendations: increase core and hip stabilization;include functional single leg balance exercisesstrengthen glutes ts), stretch hip flexors, work on quick turnover/short stride Shoes: foot strengthening exercises

Brad 25-35 Y/O Male Motivation: training for a triathlon– wants to improve speed Symptoms: mild patellofemoral pain or iliotibial band pain Classic Issues: decreased knee flexion, decreased hip extension, increased stride length, mild overpronation Key Recommendations: stretch quads and hip flexors regularly; increase running cadence by 5-8%; and or moving to a forefoot strike pattern Shoes: no change

Andrea 35-50 Y/O Female Motivation: weight loss + half marathons Symptoms: knee pain Classic Issues: valgus collapse at knee, increased pelvic drop, decreased knee flexion at initial contact, decreased hip extension, low arch, valgus heel, excessive heel eversion and overpronation Key Recommendations: core and hip stabilization + ilipsoas flexibility Shoes: try stability shoe and/or OTC orthotics

Ben 45-60 Y/O Male Motivation: lifetime runner, training for marathons Symptoms: hip pain, knee pain, arthritis Classic Issues: decreased knee flexion, decreased hip extension, decreased stride length, poor ROM throughout body, varus hindfoot Key Recommendations: general flexibility (hip flexors, quads, calves, hamstrings, spine) Shoes: cushioned shoe

Thank You!