The Latest in Running Science
I recently attended a conference for physical therapists (American Academy of Sports Physical Therapy) and wanted to pass along some of the latest studies and discoveries. If you have any questions about these, give me a call!
HIP AND KNEE KINEMATICS DIFFER BY MATURATION AND SEX IN HEALTHY YOUTH LONG-DISTANCE RUNNERS
Purpose & Hypothesis: The purpose of this study was to investigate differences in hip and knee mechanics based on maturation and sex among healthy youth long-distance runners. The researchers hypothesized (1) hip and knee frontal plane kinematics would differ among maturation groups in only females and (2) females would run with increased frontal plane hip and knee kinematics compared to males.
Study Method: Participants ran on a treadmill and knee and hip RoM and peak joint position during stance were extracted
Conclusion: Compared to male runners, female runners demonstrated greater differences in hip and knee kinematics among maturational groups. These differences have previously been linked to knee injuries in adult runners.
“NOT AGAIN”: THE PROBLEM OF RECURRENT INJURIES IN COLLEGIATE TRACK-AND-FIELD ATHLETES
Purpose & Hypothesis: Recurrent injuries are a common problem in sports, however, there is a lack of research regarding the frequency of recurrent injuries and their burden on track-and-field (T&F) athletes. The purpose of this study is to describe the frequency and burden of recurrent injuries on collegiate track and field athletes.
Study Method: Data from the NCAA Injury Surveillance Program was used to describe the frequency and proportion of recurrent injuries affecting various women’s and men’s T&F athletes competing in various events.
Conclusion: T&F runners and throwers demonstrated greater odds of sustaining recurrent injuries compared to other disciplines. Recurrent injuries caused T&F athletes to miss a greater amount of time from sport compared to new injuries regardless of sex, injury diagnosis, or NCAA division. The findings of this study suggest certain T&F disciplines may experience a greater risk of recurrent injuries, which pose a greater burden than new injuries. This area warrants further study to better understand causal factors of recurrent injuries in order to reduce their impact on T&F athletes.
RUNNING BIOMECHANICS ARE ALTERED AT RETURN TO SPORT FOLLOWING A HAMSTRING STRAIN INJURY COMPARED TO PRE-INJURY
Purpose & Hypothesis: Hamstring strain injuries (HSI) are common in running-related sports and have a high recurrence rate, suggesting deficits may be present following an athlete’s return-to-sport (RTS). Characterizing changes in running biomechanics following HSI, compared to preinjury, may improve injury management, RTS criteria, and HSI recurrence prevention methods. The purpose of this study was to compare spatiotemporal and kinematic measures during treadmill running between a healthy, preinjury time point (PRE) and RTS in athletes who sustained an HSI.
Study Method: Whole body mechanics were collected during treadmill running at PRE and at RTS following a unilateral HSI. RTS was determined by when athletes were cleared to resume full sports participation. At RTS, athletes also reported their self-perceived function on a scale of 0 to 100 (SANE score). Running metrics of interest included step rate, stride length, horizontal distance between the heel and center of mass at initial contact, knee flexion angle at initial contact, ankle negative work (NW) during stance, ankle plantarflexion impulse, propulsive ground reaction force impulse, hip NW during swing, and knee NW during swing.
Conclusion: At RTS following an HSI, collegiate athletes demonstrate bilateral changes from preinjury that may be compensations for deficits in hamstring function. The lack of between limb differences suggests that using asymmetry to assess recovery at RTS may have limited value. Of note, as many HSIs occur during high-speed running, gait analysis at submaximal speeds may not be sensitive to detect limb-specific alterations in function. This means that despite being cleared to return to full sport participation and having a perception of near normal function, athletes demonstrate altered running mechanics at RTS. In general, the observed changes reduce the biomechanical demands placed on the hamstrings during running and may result from player apprehension to fully load the recently injured muscle. It remains unknown if these altered running mechanics are a risk factor for injury recurrence.
GAIT MODIFICATION EFFECTS ON SUBJECT-SPECIFIC TIBIA STRESS DURING RUNNING IN MALES AND FEMALES
Purpose & Hypothesis: : Tibia bone stress injury (BSI) rates are high in populations that regularly participate in running. Increasing step width, using a forefoot strike (FFS) pattern, reducing step length and reducing impact loads during running are suggested to modify biomechanical factors related to tibia BSI. It is unknown which gait modification technique most effectively reduces tibia loads and if effects are sex-specific. The aim of this study was to compare acute gait modification effects on tibia stress during running in males and females.
Study Method: Motion-capture data were collected for 20 seconds while subjects ran on an instrumented treadmill in 5 running conditions. Following a preferred run condition, subjects were cued using real-time visual feedback in a random order to increase step width 5% of leg length (WIDE), use a FFS, reduce step length 10% (SHORT) and lower vertical ground reaction force load rate 15% (LOW).
Conclusion: Step length reduction, followed by increasing step width, appeared most effective in reducing running-related tibia stress, the proximate cause of BSI. Running with lower impact forces resulted in mixed effects while using a FFS increased tibia stress, likely due to greater plantarflexor forces. Gait modification effects did not vary by sex. The main takeaway from the study is that both shorter step length and wider step width running modifications are practical and effective interventions for reducing running-related tibia stress. Caution should be used when cueing runners to use a FFS or softer impact pattern due to the potential for acute increased tibia stress.