Posts in gait retraining
Accuracy of Self Reported Foot Strike Patterns

The analysis and implementation of different foot strike patterns among runners has grown over the last 10 years.  Changes in foot strike patterns have been shown to reduce loading through the leg and may help reduce the risk or symptoms associated with different running related injuries.  Many runners entering our Physical Therapy clinic state confidence in their ability to utilize a certain gait pattern (fore, mid, or rear foot striking), but often their subjective report is inconsistent with our objective video taped gait analysis.   In prior research less than 70% of runners were shown to accurately determine their foot strike pattern without confirmed video tape analysis.  

A recent research article in the International Journal of Sports Physical Therapy compared the subjective report of foot strike patterns to the objective biomechanical measurement among collegiate and recreational runners (Bade et al. 2016).  Runners were asked for their preferred foot strike pattern (fore, mid, or heel) and then tested as they ran at their preferred speed on a treadmill.  Although collegiate runners were able to more accurately identify their strike pattern (56.5 vs. 43.5%), both groups were not able to accurately identify their gait pattern.

This study highlights the importance of using a skilled Physical Therapist to analyze a runner's gait to determine its' impact on their biomechanics and injury risk.  Importantly, this may question a runner's ability to independently change their gait pattern without an objective measurement by a Physical Therapist. 

Changing Foot Strike Pattern in Distance Runners

In our Boulder Physical Therapy practice, the examination of a runner's gait is a critical part of the evaluation giving us insight into the factors which either precipitated or perpetuated a running related injury.  The forces transmitted across the body in running can be 2-4 times body weight and must be absorbed efficiently to reduce abnormal loading in a given body region such as the knee.  Foot strike pattern in a runner is one variable shown to reduce abnormal loading across the lower extremity.  In the knee example, changing from a rear to a fore or mid foot strike pattern can reduce impact forces across the knee joint.  

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Changes in a runner's step rate per minute is an easy way to change a runner's foot strike pattern with higher rates usually associated with more fore and mid foot strike patterns.  A recent article in the International Journal of Sports Physical Therapy examined 40 runners who ran at least 10 miles per week in a heel strike pattern (Allen et al. 2016).  The authors used video analysis to determine the athlete's foot strike pattern then asked the runner to run at 5, 10, and 15% above their preferred step rate to determine the rate increase's impact on their gait.  With each increase in percentage the runner's demonstrated less foot inclination (ankle bend) and thus less heel strike.  Specifically, the authors found the heel strike pattern changed to a non heel strike pattern at 10 and 15% above the preferred step rate.  

To learn more about how Physical Therapy Gait Retraining can reduce your injury risk and improve your running performance contact a local Physical Therapist. 

Treating Knee Pain in Runners

As the snows melts many of us will return to the amazing Boulder trail system for our training runs.  This popular form of exercise comes with tremendous health benefits, but can also place some runners at risk for running injuries such as knee pain.  Patellofemoral Pain (pain on the front of the knee) is the leading cause for medical consultation attributed to a running program (Taunton et al. 2002).  

Authors have suggested multiple reasons for the pain including training errors (too much volume, too soon), weakness and/or tightness in lower body muscles, and poor control of the lower extremity during the running gait cycle.  Loads on the knee joint have been measured at 4-5 times body weight during running (Roos et al. 2012) with higher loads noted in runners with knee pain (Davis et al. 2010).  Physical Therapy remains the gold standard for treatment of this disorder due its' unique ability to identify and treat the specific factors contributing the symptoms in this group of athletes. 

Prior research on knee pain in runners has shown gait retraining to be an inexpensive and effective treatment for reducing pain and improving function.  In particular, cuing to to improve step frequency and to land softer can significantly reduce impact forces at the knee during running.  A recent article in the Journal of Sports Rehabilitation expands on this research and highlights the impact of a multimodal treatment program for runners with knee pain (Esculier et al. 2016).

The authors included 21 runners with > 3 months of knee pain who were running at least 15 km per week.  These runners must have at least 3/10 pain with running and report pain with stair climbing, kneeling and squatting to be included in the study.  All of the runners were evaluated by a Physical Therapist for their running gait as well as an assessment of strength, flexibility, and control of their knee during functional testing.  Each runner underwent treatment for 8 weeks based on this initial examination performing exercises at home in addition to treatments with the Physical Therapist.  Runners were instructed to increase their step frequency to reduce the loading on their knees, as well as, to land softer to reduce the vertical loading on their legs.  

75% of the runners reported success with improved knee pain and function following the treatments.  Interestingly, the 5 runners who reported low to moderate success did not demonstrate significant changes in the forces across the knee at the end of the trial.  These athletes may require further gait retraining to make a significant impact on their symptoms.  

This study highlights the importance of running gait retraining, without the need for expensive bio-mechanical equipment, and strengthening exercises on improving pain and function among runners.  To learn more about how you can improve your knee pain and get back to running contact your local Physical Therapist.   

 

Role of Vertical Forces on Running Injuries
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It is hard to find a runner who has not missed a training run or competition due to injury.  Among the 20 million Americans who run on a regular basis about 1/3 to 1/2 will sustain a running related injury this year.  This percentage has driven a substantial amount of attention towards shoe wear, running mechanics, and Physical Therapy interventions designed to prevent or treat running injuries.  Gait retraining is one promising area making an impact on injury rates.  Examining and correcting an athlete's running form can significantly reduce pain and improve running performance.  

A recent study of close to 250 female runners used gait analysis to determine its' association with future running injury (Davis et al. Br J Sp Med. 2015).  To enter the study runners needed to be running at least 20 miles per week and be injury free over the last 6 months.  Athletes underwent a gait analysis within a Physical Therapy biomechanics laboratory and then were told to maintain a running journal including mileage and injuries over 2 years.  Over 100 athletes sought medical attention for a variety of injuries, listed below, and a surprising 21 did not report prior injury or injury during the study period.  The researchers then examined these two groups of runners for biomechanical faults which may have predisposed them to injury.

The authors reported higher rates of lower extremity loading at foot strike among the injured athletes.  In particular, the amount of vertical translation and force development between foot strike and toe off was associated with both future bone and soft tissue injury.  Clinically, these runners are identified by their "hard" or "loud" landings on the treadmill or ground.  This loading type can often be corrected through cuing to "land softer".

Running athletes are advised to have their gait analyzed by a local Physical Therapist to reduce their injury risk. 

Effect of Fatigue on Stress Fracture Risk in Runners

The tibia is the largest bone in our lower leg and absorbs the majority of weight bearing stresses during running.   The tibia's anatomy and function make it the most commonly affected area for stress fractures/injuries in runners.  These injuries account for up to half of all stress related injuries among runners (Hreljac et al. 2005).  The greatest risk factors for future stress injuries to the lower leg are seen in females with a prior history of a stress fracture.  Additional contributing factors include excessive activity with inadequate rest periods, female athlete triad (eating disorders, amenorrhea, and osteoporosis), and sudden increases in activity or training volume.  Another important factor contributing to these injuries includes an athlete's running biomechanics.  Running is a very symmetrical sport and asymmetries in an athlete's running gait can increase abnormal forces across the lower extremity.   

boulder running gait form leg injury pain

Across all sports, participating in a high level of activity while fatigued leads to poor mechanics and increased injury risk.  Runners who are fatigued from previous workouts or within a single workout are exposed to higher levels of mechanical stress across the lower body.  A recent study in the journal Medicine and Science in Sports and Exercise examined the impact of fatigue on running mechanics and lower body forces (Clansey et al. 2013).  Authors studied the biomechanics of 21 experienced distance runners both before and after a high intensity run to fatigue.  As expected, the runner's biomechanics changed for the worse in the fatigued state leading to increased forces across their legs.  These abnormal forces have previously been associated with tibia stress fractures in runners.

Runners are advised to keep a close eye on their running volume to avoid training errors and poor mechanics associated with a fatigued musculoskeletal system.  Runners should also consider working with a local Physical Therapist to analyze and correct their running gait for poor mechanics associated with injury.  

Improving Running Economy to Improve Performance

In running, performance is easily quantified as the fastest time over a given distance.  The runners with the fastest times often have the best ability to utilize oxygen (VO2 max), process metabolites and substances involved in energy utilization (lactate threshold), and the most efficient running form.  Efficiency in running is described as running economy, similar to miles per gallon in a car, how much energy is expended to run a given distance and speed.  Interestingly, prior research has shown running economy is more predictive of running performance than VO2 max levels (Morgan et al. 1989).  As with many physiological variables there is significant variability in economy between runners with similar VO2 max levels.  Thus two runners can complete a run of the same distance in the same time, but expend different levels of energy.  Imagine an amateur athlete completing a training run with a professional runner.  The professional runner will be at a significantly lower intensity than the amateur. 

Among most runners an increase of 5-20% in VO2 max is observed with aerobic training, but genetics also limit the maximum level of oxygen utilization during activity.  Thus runners trying to improve their running performance should also consider beneficial changes in running economy.   Factors influencing running economy can be broken down into two categories, intrinsic factors inherent to the athlete and extrinsic factors such as running surface and shoe wear.  A recent review article in the journal Sports Medicine highlighted the evidence behind improving running economy (Moore et al. 2016).

A runner’s optimal stride length is mostly self determined by the athlete and represents a self-selected economical running form.  In trained runners stride length is on average 3% greater than optimal, but this percentage can be up to 8% in a novice runner (Ferrauti et al. 2010).   Making small changes in stride length can often improve running economy especially in the novice runner. 

Another variable highlighted in the article involved improving running biomechanics to improve running economy.  Energy wasted in the vertical and rotational planes by the upper or lower body are detrimental to increasing horizontal plane speed and efficiency.  For example, the amount of vertical or rotational displacement observed in the running cycle has been shown to adversely effect economy.  Surprisingly, time in contact with the ground has been an inconclusive variable to improve economy.  Faster stride frequency may reduce injury risk or pain with running, but also impacts energy required during running.  A tradeoff is observed between high stride frequency leading to increasing deceleration muscle costs vs. a lower stride frequency leading to increased energy absorption and potential injury risk.   Despite a commonly reported statement by tribes of runners there is inconclusive evidence that forefoot vs. rearfoot running is more economical. 

A final variable to consider would be the range of motion and muscular effort observed at the lower extremity joints between landing and push off.  An athlete will burn more energy per step if their hip, knee, and ankle move through greater ranges of motion compared to a more efficient runner.  Thus minimizing unnecessary movements will improve running economy and performance.

boulder running form retraining performance

The pros and cons of these variables on a runner's gait must be considered before making any changes.  Thus, runners interested in reducing injury risk and improving performance should utilize gait analysis by a Physical Therapist to evaluate their running gait and determine the most appropriate modifiable factors