The Effect of a Gait Modification Training Program on Impact Loading and Running-related Injuries
Phase: NA
Conditions: Athletic Injuries
Sponsor: University of British Columbia

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Official Title: 
The Effect of a Gait Modification Training Program on Impact 
Loading and Running-related Injuries 
 
NCT Number:  
NCT03302975 
 
 
 

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The Effect of a Gait Modification Training Program on Impact Loading and 
Running-related Injuries 
 
 
Objectives 
The purpose of this study is to determine whether a gait modification training 
program can result in a reduction in impact loading and the incidence of running-related 
injuries (RRI) among recreational distance runners. Knee angle at initial contact (IC) has 
been identified in a previous study by the principal investigator (pre-submission stage) as 
both increasing the average vertical loading rate (AVLR) and the incidence of RRI in the 
female recreational running population. This variable will be modified to determine the effect 
on impact loading (AVLR) and incidence of RRI using a repeated measures design.  
 
Background 
Numerous studies have shown that individuals can be trained to modify aspects of 
walking and running[1-18]. Moreover, gait retraining has been shown to be effective in 
treating overuse injuries in runners[4,7,8,18]. However, since it is unclear what variables 
independently contribute to the recovery from these injuries and whether these variables 
can be manipulated prospectively to reduce the risk of injury, optimal prevention and 
treatment of RRI remains unknown. These studies all included some form of feedback to 
the subjects, which helped them modify their technique. The feedback methods included 
verbal instructions and real-time visual[1,3,6,7,9,12,17,18] or auditory 
information[4,5,8,11,15,16]. Other studies used verbal instructions and videotape 
reviews[13,14] or an extensive training program[8,19]. Many of these studies have used 

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overlapping instructions and feedback which make it difficult to infer which factors had a 
causative effect on changing gait mechanics, muscle activation patterns, and ground 
reaction forces. Others have used feedback that is difficult to reproduce outside of a lab 
or clinic environment. Simple cues that produce a specific and intended kinematic or 
spatiotemporal modification are necessary. Furthermore, these cues need to be consistent 
and reproducible in multiple training environments in order to be retained as part of the 
motor program. 
Arendse et al[19] reported that 7.5 hours of training over 5 consecutive days was 
required to learn FF landing, while Dallam et al[20] reported a 1-hour session for 12 
weeks was necessary. Diebal et al showed FF landing could be trained in 6 weeks, with 
training sessions 3 times per week for 45 minutes[8]. An 8-session faded-feedback 
approach was used by Barrios et al to retrain walkers. This design produced changes in 
lower extremity biomechanical variables immediately post-intervention as well as at 1-
month follow-up [1]. Subjects who receive intermittent feedback have been shown to 
perform better in the long-term than subjects who receive continuous immediate 
feedback[21,22]. Removing the feedback is beneficial to motor skill learning because the 
subjects must rely on internal cues for performing correct motor patterns[23]. 
Some researchers have suggested that further studies should investigate the effect 
of gait retraining on injury prevention in runners[8,19]. Changing a runner’s gait to 
reduce the risk of a certain injury, however, may have unintended consequences such as 
increasing the chance of another kind of injury if other kinematic or spatiotemporal 
variables are adversely impacted[2,19]. Knowledge of the independent contributions of 
identified kinematic and spatiotemporal risk factors to impact loading and injury 

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incidence will allow for targeted modification of these variables so that the risk of 
negative consequences is limited. 
 
Hypotheses 
It is hypothesized that after a 15-week training program, a change in knee flexion 
at IC will be significant (p < 0.05) and will result in decreased impact loading (AVLR) 
and incidence of RRI. 
 
Outcome Measures 
 
Primary outcome measures: 
1) Kinetic outcomes: Average vertical loading rate (Body weights [BW] 
per second) and vertical impact peak (BWs). 
2) Incidence of RRI (calculated as the number of new injuries reported 
per 100 runners at risk). 
 
Secondary outcome measures:  
Secondary outcome measures will be kinematic and/or spatiotemporal 
correlates of impact loading and incidence of RRI as guided by the literature and 
determined in previous studies.  
1) Knee flexion angle at IC 
2) Peak knee flexion angle 
3) Angle of the shank at IC 
Other outcome measures: 

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Other outcome measures will be collected to describe and assess the 
success of the gait modification intervention. These measures include: 
1) Participant compliance: Participant compliance with the gait 
modification intervention will be measured by the number of training 
sessions attended at Fortius (to a maximum of 8, converted to a 
percentage) and the number of home training sessions completed (to a 
maximum of 22, converted to a percentage). Participants will record 
their home training sessions in their weekly online questionnaire. 
2) Adverse events: Adverse events experienced due to the intervention 
(i.e. increased pain or a new injury) will be recorded in the weekly 
online questionnaires. 
3) Fidelity of training sessions: Assessed by calculating the difference 
(error, in degrees) between the intended target angle and the actual 
angle produced during the 10 consecutive stance phases at each of the 
four time points during each training session (first min, 33%, 66%, and 
last min) and averaged within the session. 
4) Perceived difficulty in achieving targeted modification: Assessed at 
each training session using an 11-point numerical rating scale (NRS) 
(0 = “no difficulty”, 10 = “unable to perform”). 
5) Pain: Assessed at each training session using an 11-point NRS (0 = 
“no pain”, 10 = “worst pain imaginable”). 
6) Rating of Perceived Exertion (RPE): Assessed at each training session 
using the 15-point Borg RPE scale. 

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7) Anthropometric and functional measurements: These will include 
BMI, navicular height, hip internal/external rotation range of motion, 
Q-angle, and weight-bearing ankle dorsiflexion and knee valgus angle. 
 
Methods 
The proposed study is a repeated measures design. A sample size calculation for 
comparing injury incidence is based on our current injury rate (27.9%) in our previous 
studies. We calculate that we will require a sample size of 30 to achieve a minimum 
power of 80% (α = 0.05). Thirty uninjured female recreational runners will be recruited 
through advertisements in Vancouver-area running clinics. Participants must be female 
between the ages of 18 and 60; have been running for at least three months prior to study 
commencement; and have experience with running on a treadmill. Participants must not 
have run more than two half marathons previously. Participants will be excluded if they 
have experienced a lower extremity injury in the prior three months; have undergone hip, 
knee, or ankle joint surgery; or currently have pain in their lower back or lower 
extremities while running.  
Eligible participants will first be screened for the biomechanical trait in question 
(less than 10° of knee flexion at IC). A historical control group from a previous study will 
be used as a comparison group and a sample that meets the same screening criteria will 
be matched for age and BMI. 
Demographics and a detailed training and injury history will be taken for each 
subject, which will include information on running experience, previous best times at 
5km, 10km, half marathon and marathon distances (if available), and overall number and 

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type of general musculoskeletal and/or running injuries. Anthropometric and functional 
measurements (including height, mass, foot length, navicular height, hip internal/external 
rotation range of motion, Q-angle, and weight-bearing ankle dorsiflexion) will be 
collected prior to treadmill testing for descriptive purposes and for use as covariates. 
Participants will wear their regular running shoes. 
Using an eight-camera passive marker system (Qualisys Motion Capture Corp., 
Gothenburg, Sweden) and Visual 3D software (C-Motion, Inc., Germantown, MD), 
participants will undergo a static calibration trial to form a musculoskeletal model. 
Anthropometric properties of body segments will be scaled to each individual using the 
subject’s height, mass, and segment lengths. Each model segment position will be 
multiplied by the respective mass; these numbers will then be summed and divided by the 
total body mass. For bilateral analysis, 19 static/calibration markers and 42 tracking 
markers (total = 61) will be affixed to each subject. Before data collection, each subject 
will be allowed 5 minutes to warm-up and determine their speed. Participants will be able 
to adjust the speed as needed over this period until they identify a speed that is 
representative of a typical moderate intensity run. Participants will then be asked to 
identify their rating of perceived exertion (RPE) using Borg’s RPE scale [33]. The speed 
will be adjusted until the participant is at an RPE of 13 (“Somewhat hard” or 70% effort). 
Three-dimensional kinematic and spatiotemporal data will be collected at this pace over 
three trials of 15 seconds using the six-camera, three-dimensional motion analysis 
system. Kinetic data will be collected using an embedded force platform in the 
instrumented treadmill. All kinetic variables will be normalized to subject body mass. 
Initial contact and toe-off will be identified by force plate data (using a threshold of 50N). 

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These data points will be used to determine the stance and swing phases of the gait cycle. 
All outcome measures will be determined by averaging the first 10 consecutive stance 
phases within each of the three trials (n = 30 total stance phases). For the purposes of 
comparison between RF strikers and MF/FF strikers (who may not display a clear VIP), 
AVLR will be calculated for all individuals as the slope of the vertical GRF–time curve 
from IC to 13% of stance. This time value has been shown to be the best surrogate for the 
timing of a missing VIP.  
Participants will follow a 15-week half-marathon training program, wearing their 
regular running shoes throughout the study. During the training program, participants will 
attend the Fortius Biomechanics Lab on Weeks 1, 2, 4, 6, 8, 10, 12, and 14 (eight sessions 
in total) for a 15-30 minute gait modification training session following a faded-feedback 
design (figure 1)[1]. The aim of these sessions will be to modify the angle of knee flexion 
at IC so that it is greater than 10 degrees. Gait modification will be facilitated through the 
use of real-time biofeedback of performance[1,24,25] at each training session. The co-
investigator, a sport physiotherapist, will also provide standardized verbal instructions to 
change the desired biomechanical outcome (e.g. “Land with a more bent knee”). For the 
first four sessions, participants will receive feedback for 100% of the session. By the 
eighth session, feedback will be provided for just 10% of the session (minutes 1, 15, and 
30). All participants will have a total of 60 running sessions (four times per week for 15 
weeks). During the weeks in which a lab-based gait modification session is scheduled, 
participants will have one lab-based biofeedback session and three “regularly scheduled” 
run sessions in which they will be instructed to focus on the same cues given in the lab 
during their runs. During the weeks in which no lab-based feedback session is scheduled, 

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participants will only have the four “regularly scheduled” run sessions in which they will 
be instructed to focus on the same cues given in the lab during their runs. This will ensure 
that they do not have any more run sessions than the historical control group.  
 
Figure 1. Faded-feedback design depicting time spent running on the treadmill 
during each session and time with visual real-time biofeedback for each session. For 
the first four sessions, participants will receive feedback for 100% of the session. By the 
eighth session, feedback will be provided for just 10% of the session. 
 
Kinetic, kinematic, and spatiotemporal data will be collected during each session 
to ensure that the goal of the intervention is being achieved. This will be assessed by 
calculating the difference (error, in degrees) between the intended target angle and the 
actual angle produced during the 10 consecutive stance phases at each of four time points 
during each training session (first min, 33%, 66%, and last min) and averaged within the 

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session. 
Pain, RPE, and perceived difficulty in achieving the targeted modification will be 
measured in all training sessions using an 11-point NRS (pain and perceived difficulty) 
and the Borg RPE scale. Adverse events (increased pain or a new injury) and participant 
compliance with the gait intervention will be assessed in the weekly online questionnaire. 
All participants will return to the Fortius Biomechanics Lab at the conclusion of 
the 15-week half-marathon clinic for retesting. A one-month post-test will also be 
performed to assess for retention. During both sessions (follow-up and retention), the 
participants will be asked to run naturally and then with the modified pattern. The natural 
pattern will be collected to determine whether it has changed since baseline. 
The verbal instruction during each training session will be given by the principal 
investigator (a sport physiotherapist with clinical experience in gait retraining). The 
therapist will not be involved in data collection, but will process the data. To ensure 
blinding, data will be collected by an independent lab assistant and coded to blind for 
participant number for later processing and analysis by the principal investigator. This 
process will ensure that the principal investigator is unaware of which participant they are 
analyzing until the conclusion of the study. 
Demographic, anthropometric, and functional variables will be analyzed for 
differences between the intervention group and a historical control group from our 
previous studies at baseline using 2-tailed t-tests for normally distributed continuous 
variables. Injury incidence (number of new injuries reported per 100 runners at risk) will 
be compared between groups using paired t-tests. Differences in outcomes pertaining to 
the feasibility of the intervention (perceived difficulty, exertion, fidelity, compliance) will 

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be assessed in the intervention group between session 1 and 8 using paired t-tests. The 
biomechanical and clinical outcomes from the follow-up and one-month post-
intervention modified patterns will be compared to the baseline values using ANOVAs 
for repeated measures. Planned pairwise comparisons between the visits will be 
conducted. Differences will be considered statistically significant at p<0.05.All statistical 
analyses will be performed using SPSS version 22.0 (SPSS Inc., Chicago, IL). 
 
 
 
 

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