Posts tagged running mechanics
What is the best way to reduce loading forces in runners?
running-forces-reduction-injury

In our previous blog posts we have discussed the variety of interventions available to reduce the high injury rates seen among both novice and experienced runners.  Many of these interventions are designed to reduce the loading forces across the lower body at foot strike and push off.  In our Boulder Physical Therapy practice we commonly utilize strength training, patient education, and running gait retraining.  No consensus has been reached on the an ideal running form for all individuals, but each runner can improve their gait efficiency and injury risk through analysis and form correction.  We often find simple cues such as "land softer" are most effective at improving a runner's gait.  With runners, like most athletes, complex and multiple cues only lead to "paralysis by analysis".  Most often these cues are designed to improve step frequency (cadence) or vertical oscillation.  A new study provides insight into which cue may be most effective.

Adams and colleagues analyzed healthy runners under 3 running conditions: self selected running gait, cuing to increase step frequency, and cuing to reduce vertical oscillation (International J Sports PT. 2018).  Data on vertical loading, ground reaction forces, and braking impulse during each condition were analyzed in a biomechanics lab.  Although both the vertical oscillation and step frequency groups demonstrated improved loading measurements compared to the baseline group greater improvements were seen among the runners aiming to reduce their vertical oscillations. 

These findings are consistent with prior research indicating runners with high vertical oscillation rates (picture greater up and down movements with each stride) not only are more inefficient but also have greater rates of lower body loading and injury risk. 

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Influence of Shoe Type and Foot Strike Pattern on Loading Rates in Runners

The selection of running shoes continues to be a controversial topic in the sport.  Arguments are heard from both sides of the running shoe continuum from barefoot/minimalist to heavily cushioned shoes.  Both groups advocate their product based on its' perceived influence on reducing the large numbers of running injuries seen every year among both recreational and professional runners.  In addition to shoe wear many athletes are pushed toward either a fore or rear foot strike gait pattern to reduce adverse loading during each foot contact with the ground.  As we have noted in a previous post their are benefits to both contact approaches.

A recent study by Harvard University's Spaulding National Running Center examined the impact of foot strike pattern and shoe wear on loading rates during running (Rice et al. Med Sci Sp Ex. 2016).  The authors studies 29 healthy runners as they ran in their preferred gait pattern and shoe type.  Not surprisingly, athletes who used minimalist shoes with a fore foot running pattern had the lowest force rates compared to runners who ran in either foot strike pattern in traditional running shoes.  Authors noted runners who habituated to the minimalist shoe and used a fore foot strike pattern had the lowest impacts at landing.  Among the runners using standard shoes, similar load rates were noted between forefoot and rearfoot patterns.   

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. 

Physical Therapy Running Gait Retraining for Knee Pain

In our Boulder Physical Therapy Practice, gait retraining is an effective intervention to reduce the abnormal forces which perpetuate many overuse running injuries.  Athletes are videotaped by Physical Therapists for bio-mechanical faults including alignment, stride length, step rate, and running technique.  The athlete is then given real time feedback to correct the faults associated with their respective injury.  In the example above, the athlete demonstrates improved pelvic stability and knee control using the real time feedback.  These gait retraining treatments are gaining momentum in the literature with more studies demonstrating their effectiveness among various running injuries.  

A recent article examined the impact of gait retraining by a Physical Therapist on 16 patients with knee pain (Roper et al. 2016).  Athletes were randomized to either a gait retraining group or a control group.  Those in the gait retraining group received 8 feedback sessions over 2 weeks allowing the athletes to improve their running form and reduce impact forces across their knees.  Conversely, those in the control group ran for the same duration of time but were not provided any verbal feedback. The benefits of the gait training were found immediately after treatment and one month after their last treatment session.  

Runners with knee pain are encouraged to follow up with a local Physical Therapist to both reduce their pain and improve their running technique.

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.