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The habitual motion path theory predicts that humans tend to maintain their habitual motion path (HMP) during locomotion. The HMP is the path of least resistance of the joints defined by an individual’s musculoskeletal anatomy and passive tissue properties. Here we tested whether participants with higher HMP deviation and whether using footwear that increases HMP deviation during running show higher reductions of knee joint articular cartilage volume after 75 minutes of running. We quantified knee joint articular cartilage volumes before and after the run using a 3.0-Tesla MRI. We performed a 3D movement analysis of runners in order to quantify their HMP from a two-legged squat motion and the deviation from the HMP when running in different footwear conditions. We found significantly more cartilage volume reductions in the medial knee compartment and patella for participants with higher HMP deviation. We also found higher cartilage volume reductions on the medial tibia when runners wore a shoe that maximized their HMP deviation compared with the shoe that minmized their HMP deviation. Runners might benefit from reducing their HMP deviation and from selecting footwear by quantifying HMP deviation in order to minimize joint cartilage loading in sub-areas of the knee.
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The habitual motion path theory:
Evidence from cartilage volume
reductions in the knee joint after
75 minutes of running
Steen Willwacher1*, Daniela Mählich1, Matthieu B. Trudeau2, Joseph Hamill3, Gillian Weir3,
Gert-Peter Brüggemann1 & Grischa Bratke4
The habitual motion path theory predicts that humans tend to maintain their habitual motion path
(HMP) during locomotion. The HMP is the path of least resistance of the joints dened by an individual’s 
musculoskeletal anatomy and passive tissue properties. Here we tested whether participants with
higher HMP deviation and whether using footwear that increases HMP deviation during running show
higher reductions of knee joint articular cartilage volume after 75 minutes of running. We quantied 
knee joint articular cartilage volumes before and after the run using a 3.0-Tesla MRI. We performed a 3D 
movement analysis of runners in order to quantify their HMP from a two-legged squat motion and the 
deviation from the HMP when running in dierent footwear conditions. We found signicantly more 
cartilage volume reductions in the medial knee compartment and patella for participants with higher
HMP deviation. We also found higher cartilage volume reductions on the medial tibia when runners
wore a shoe that maximized their HMP deviation compared with the shoe that minmized their HMP
deviation. Runners might benet from reducing their HMP deviation and from selecting footwear by 
quantifying HMP deviation in order to minimize joint cartilage loading in sub-areas of the knee.
Overuse injuries in distance running occur with gradual onset over time and result from the repetitive stress of
biological tissues and associated cumulative trauma1. e knee joint is the most common site for running-related
overuse injuries (RROIs)2. Nigg et al. have proposed that the neural control of running is tuned towards mini-
mizing mechanical stress of biological tissues, resulting in an optimal path of lower extremity joint movement for
each individual and every specic movement3. Recently, we proposed a redenition of this theory by assuming
that the neural control of running is tuned towards keeping the individual’s habitual joint motion path (HMP),
which we dene as the joints’ path of least resistance, and a function of an individual’s anatomy and passive tissue
mechanical properties4. As such, the HMP is the set of joint kinematics during motions which minimizes loading
of lower extremity joints relative to the loads during running. Examples for these relatively low loading motions
are walking, stair climbing, sitting down or standing up from a chair. Consequently, we have developed a simple
method to estimate the HMP for individuals from a basic half-squat movement4.
Running at typical distance running speeds requires greater force application to the ground in order to satisfy
the body weight support requirement during shorter ground contact times compared to walking5,6. erefore,
runners must generate amplied lower extremity joint moments when running in order to maintain the HMP
and to optimize the load distribution to regions that have been adapted to carry these loads. Based on the HMP
theory, deviating from the HMP leads to loading of less adapted structures of lower extremity joints, resulting in
a greater risk of sustaining a running-related overuse injury. From the same theoretical background, we proposed
that running footwear selection should account for the minimization of the deviation from the HMP4. Footwear
that does not fulll this task would lead to deviation from the HMP or additional muscle activity to keep the
HMP. Both of these consequences would result in greater loading of joint structures.
1Institute of Biomechanics and Orthopaedics, German Sport University, Cologne, Germany. 2Brooks Sports
Inc., Seattle, Washington, USA. 3Biomechanics Laboratory, University of Massachusetts, Amherst, MA, USA.
4Department of Diagnostic and Interventional Radiology, University of Cologne, Cologne, Germany. *email:
s.willwacher@dshs-koeln.de
OPEN
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e HMP theory was derived from the assumption that the neural control of running is adjusted to avoid
irreversible injuries such as osteoarthritis. ese optimization strategies might have also been essential for human
evolution7. While the HMP theory was developed from a sound theoretical background, it has only very rarely
been tested empirically4,810.
Measuring the loads imposed on cartilage structures in a running participant non-invasively in-vivo is not
feasible using current technology. Nonetheless, with high-resolution magnetic resonance imaging (MRI) one can
measure cartilage volumes before and aer a prolonged run1114. Cartilage volume may act as a surrogate variable
to indirectly quantify the loading imposed onto the cartilage15. Knee joint cartilage morphology has been related
to biomechanical loading characteristics of the knee during locomotion15.
erefore, the purpose of the present study was to test hypotheses derived from the HMP theory. Specically,
we hypothesized that knee joint cartilage loading, quantied via cartilage volume reductions aer 75 minutes of
running, would be lower in runners who maintained a lower HMP deviation during running compared to run-
ners who deviated more from their HMP. Further, we hypothesized that specic footwear that minimized HMP
deviation in a runner would also minimize cartilage volume reductions during prolonged running. Due to the
high prevalence of RROI at the knee2, we focused on the knee joint in this study.
Methods
Subjects and materials. We recruited twelve participants (seven males and five females; height:
1.77 ± 0.08 m; body mass: 70.9 ± 9.9 kg; age: 29 ± 4 years) for this study which involved a unique multi-visit MRI-
based protocol. All participants were recreational runners and were injury free for at least one year before the
study. None of the participants had known injuries of the articular cartilage of the knee joint. e ethics commit-
tee of the University of Cologne, Cologne, Germany had approved the study protocol. All procedures were carried
out in compliance with the declaration of Helsinki. We obtained written informed consent from all participants.
We performed data collection sessions during 4 dierent days, both in a biomechanics laboratory (1 visit) and
in the MRI facilities of the University hospital (3 visits; at least one week between individual visits).
Running mechanics and habitual motion path determination. In the biomechanics laboratory, we
analyzed the 3D running kinematics and kinetics of the participants while running on a 3D force instrumented
treadmill (Treadmetrix, Park City, UT, USA) at the participants’ self-selected speed using three dierent footwear
conditions. e participants selected the running speed based on experience such that they would feel comforta-
ble keeping the speed for 75 minutes.
e three footwear conditions were: (1) a neutral running shoe (either Brooks Launch or Brooks Glycerin,
based on individual preference) with a homogeneous density ethyl vinyl acetate (EVA) midsole (Control) without
any modications; (2) a Brooks Launch shoe modied by inserting sti plastic tubes along the lateral part in the
midsole (shoe A); and (3) a Brooks Launch shoe modied by inserting sti plastic tubes along the medial part
in the midsole (shoe B) (see Fig.1). We created the custom footwear conditions 2 and 3 using the same baseline
shoe; i.e., when hardening one side of the midsole by inserting plastic tubes, the holes on the other side were le
empty which eectively reduced the midsole hardness on that side. is way, a medial post was created when
inserting tubes on the medial side and vice versa.
We measured runner kinematics using a twelve-camera optoelectronic 3D motion capture system (MX40,
Vicon Motion Systems, Oxford, UK). We used a ve-segment rigid body model of the pelvis and the right lower
extremity to determine 3D joint kinematics. e details of the model can be found in previous publications1618.
During the same lab visit, the subjects performed ten two leg half-squat movements in sock shoes, which
consisted in running socks that have been glued to standard sock liners made out of 5.5 mm EVA foam4,19, at
self-selected speed. e participants placed their feet hip width apart with their feet pointing forwards. From
these movements, we estimated the knee joint HMP of each participant while following our recently published
protocol19. In brief, this protocol quanties the frontal and transverse plane knee joint angles at a knee exion
angle of 40 degrees during the eccentric phase of the half-squat. With this approach there was only one HMP
baseline to compare against running in the dierent footwear conditions. Please refer to the Supplementary
Materials (Supplementary Fig.1) for a graphical illustration of the deviation quantication. Aer determining
the HMP baseline from the half-squat, the protocol determined these angles at the same critical exion angle dur-
ing the eccentric part of the contact phase in the running movement. By subtracting the knee non-sagittal plane
angles during the squat baseline from the knee angles obtained in the running movement, the HMP deviation
Figure 1. Experimental shoe conditions used in this study. We created a laterally posted condition by inserting
plastic tubes in the lateral border of the midsole (A) and a medially posted condition by inserting plastic tubes
along the medial border of the midsole. (B) e neutral shoe was a neutral running shoe (either Brooks Launch
or Brooks Glycerin) without any holes or tubes within the midsole (not shown).
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was quantied. Since transverse and frontal plane ranges of motion at the knee joint in running are dierent, we
determined the overall HMP deviation by using a weighted sum of frontal and transverse plane deviations using
the following formula:
=+.⋅
−−
DevDev 05 Dev, (1)
HMPTot HMPFront HMPTrans
where DevHMP-Tot is the total HMP deviation in the running movement, DevHMP-Front is the HMP deviation within
the frontal plane and DevHMP-Trans is the deviation within the transverse plane of motion.
MRI data collection during prolonged running. In the MRI facilities, we installed a treadmill directly
in front of the MR room in order to minimize the time between running and MRI measurements, and additional
loading to the knee. On dierent days, each participant ran 75 minutes at the same speed as during the biome-
chanical assessment in three dierent footwear conditions. e individual running sessions were completed in
randomized order within a time period of less than four weeks. Measurements were taken at the same time of the
day for all participants.
We performed knee MRI scans before (pre-run) and immediately after (post-run) each running bout.
Furthermore, we performed additional MRI scans of the calf muscles at 2.5, 5, 10, 15 and 45 minutes, which
were not related to the purposes of this study. ese scans interrupted the treadmill running by 3:40 minutes on
average. All participants completed a 30-minute rest phase before the pre-run scan which involved lying on the
MR table outside of the MRI scanner so that the participitants could be placed within the scanner without further
movement or loading of the knee. We took the pre-run MRI scan for the segmentation aer the acquisition of the
survey and anatomical proton-density weighted images which lasted another 15 minutes, which meant an overall
rest of 45 minutes before the pre-run scan Each participant entered the MRI scanner within ten seconds following
the 75-minute run. e start of the scan occurred less than a minute aer nishing the run. Given the short time
between the end of the run and the completion of the scan, we believe that the subjects’ cartilage recovery was
minimal, and therefore that we were able to capture eects from the prolonged run.
We performed the multiple-slice MRIs on a 3.0 Tesla scanner (Ingenia, Philips N.V., Amsterdam, Netherlands)
with a 16-channel high resolution transmitting and receiving knee coil. We carefully positioned the participants
in a supine orientation while centering the knee joint center within the magnet and attached with the knee coil.
We used a 3D water selective (WATS) T1 gradient echo sequence (repetition time: 11 ms; echo time: 5.6 ms; ip
angle: 10°) with a eld of view of 160 × 160 × 90 mm and 180 partially overlapping slices (gap: 0.5 mm). e
size for the acquired voxels was set to 0.493 × 0.493 × 1 mm and 0.286 × 0.286 × 0.5 mm for the reconstruction
voxels. e eective scan duration was 5:27 minutes for the complete sequence while using parallel imaging for
faster image acquisition (SENSE factor 2).
We conducted segmentation of the total subchondral bone area (Piscoya et al., 2005) and the cartilage joint
surface area (AC) by manual segmentation on a section by section basis with a B-spline Snake algorithm (deform-
able contour) using custom soware (Chondrometrics GmbH, Ainring, Germany). We divided the knee joint
into seven anatomical regions14,20 (Fig.2A): patella (P), medial tibial compartment (MT), lateral tibial compart-
ment (LT), the medial (MF) and lateral (LF) femoral condyles, and medial and lateral central (weight bearing
area) femoral condyles (CMF and CLF). In these anatomical regions, we calculated the cartilage volume (VC)
from three-dimensional reconstructions. We normalized cartilage volumes to body mass and height, and quan-
tied dierences between pre and post run cartilage volumes. We expressed these cartilage volume reductions as
percentage dierences relative to the pre-run condition.
Statistical analysis. We applied one-tailed Wilcoxon rank sum tests to determine whether the relative car-
tilage volume reductions of the runners with the highest overall HMP deviation (n = 6) were higher than those
of the runners with the lowest HMP deviation (n = 6). To improve the robustness of this analysis, we averaged
cartilage volume reductions and HMP deviation values over all three footwear conditions. We further performed
comparisons between the footwear conditions with the highest and the lowest individual HMP deviation values
using dependent sample t-tests. In addition to these pairwise comparisons, we performed simple linear regression
analyses to identify potential relationships between HMP deviation and cartilage volume reductions. We set the
level of signicance for all tests to 0.05. We quantied eect sizes for between group and between footwear com-
parisons (Cohen’s d,21) using
=
+
d
xx
,
ji
ss
2
ji
22
with
xij
, being the average and
sij
,
2
being the sample variance of the group or footwear data. Eect sizes of 0.2
were considered as small, 0.5 as medium, and 0.8 as large21.
All statistical analyses were performed using Matlab soware (R2018b, Statistics and Machine Learning
Toolbox, e Mathworks, Natick, MA, USA).
Results
e participants ran the 75-minute running trials at a constant speed of 2.78 ± 0.38 m/s. e fastest individual
performed the running trials at 3.33 m/s and the slowest at 2.31 m/s. We observed signicant reductions in car-
tilage volume in all knee joint sub areas aer the 75-minute run compared to the pre-run condition (Fig.2B–D).
Runners with greater overall HMP deviation values (n = 6, average over all footwear conditions: 12.5 ± 2.7°)
were characterized by greater cartilage volume losses in the MT (p = 0.047), MF (p = 0.033) and P (0.033)
sub-areas of the knee joint cartilage compared to runners with lower HMP deviation values (n = 6, average over
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all footwear conditions: 6.2 ± 2.3°)(Fig .2B,C). ere were no signicant dierences between HMP deviation
groups with respect to body mass (p = 0.94; high deviators: 69.7 ± 8.6 kg, low deviators: 70.2 ± 14.9 kg) and
body height (p = 0.85; high deviators: 1.77 ± 0.07 m, low deviators: 1.78 ± 0.13 m). We did not nd a system-
atic dierence in self-reported physical activity levels between high and low HMP deviator groups. Further, we
found no signicant dierences in running speed between the two groups of runners (p = 0.38; high deviators:
2.71 ± 0.41 m/s, low deviators: 2.93 ± 0.42 m/s).
We identied a signicant relationship between overall HMP deviation and the amplitude of MT (R² = 0.43;
p = 0.031) and MF (R² = 0.35; p = 0.045) sub area cartilage volume reductions.
For each participant, we determined the shoe with the greatest overall HMP deviation and the shoe with the
least HMP deviation. ree, three and six runners had the greatest HMP deviation in the laterally posted, medi-
ally posted and neutral shoe conditions, respectively. Two, seven and three runners had the least deviation in the
laterally posted, medially posted and neutral shoe conditions, respectively.
Within the footwear conditions associated with the least overall HMP deviation (8.2 ± 5.9°; Fig.3) compared
to the shoes with the highest HMP deviation (10.6 ± 4.7°; Fig.3), we found signicantly lower cartilage volume
reductions in the MT sub-area (p = 0.004, Fig.2D). We identied a strong linear relationship between the dier-
ence between the two extreme footwear conditions in frontal plane deviation and the dierence between these
shoes in cartilage volume reductions in the CMF sub-area (R² = 0.58; p = 0.004).
e dierences in overall HMP deviation between the high and low HMP deviation groups were greater than
the dierences within subjects when comparing the highest and lowest deviation footwear condition (Fig.3).
Discussion
e purpose of the present study was to test hypotheses derived from the HMP theory using cartilage volume
reductions as a variable for the indirect quantication of knee joint cartilage loading. We found greater carti-
lage volume reductions in the medial compartment of the knee in runners with greater deviation from their
HMP baseline compared to runners with lower deviation from their HMP baseline. erefore, we accept our rst
Figure 2. (A) Schematic drawing of cartilage sub-areas of interest in this study. (B) Individual response in
cartilage volumes to the 75-minutes running intervention. Individual data points are the average of the three
footwear conditions. Bold data points/lines indicate the mean values of the high and low deviation groups. In
each column the le value is the pre-run cartilage volume and the right value is the post-run cartilage volume. (C)
Relative post-run cartilage volume reductions between post-run and pre-run measurements (means – standard
deviations) between runners with high HMP deviation and runners with low HMP deviation in the dierent knee
joint sub-areas. * indicates a signicantly higher cartilage volume reduction in the High HMP deviation group
(p < 0.05). (D) Relative post-run cartilage volume reductions compared to pre-run (means – standard deviations)
between the footwear conditions with the highest and lowest overall HMP deviation. *Indicates a signicant
dierence between the two footwear conditions at a level of p < 0.05.
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hypothesis. Furthermore, we found signicantly less cartilage volume reduction in the MT sub-area when run-
ners wore footwear with the smallest amount of HMP deviation compared to footwear with the highest amount
of HMP deviation. erefore, we also accept our second hypothesis as it relates to the MT sub-area of the knee.
Cartilage volumes of the femur, tibia and patella cartilage in our study were consistent with previous literature
(e.g.11) and indicated a high variability of cartilage volume of the analyzed sample (Fig.2B). Previous studies also
reported reduced cartilage volumes aer running exercise of dierent durations and distances1113,22. Boocock
et al.11 identied a reduction of lateral tibial (5.7%), medial femoral (5.3%) and lateral femoral (4.0%) cartilage
volumes aer a 30-minute running trial. Aer a 5 km run, Kessler et al.22 reported a decrease in the patella (6.6%)
and tibial (3.6%) cartilage volumes. In general, the cartilage volume reductions reported in this study aer the
75-minute running bout agree with previous literature and 30-minutes loading scenarios1113,22.
e results of our study indicate that deviating from the habitual motion path was associated with increased
cartilage volume loss in some regions of the knee joint during a prolonged run. is suggests that deviating from
the habitual motion path may lead to greater loading on some regions of the knee joint. e greater cartilage
volume reductions in runners with greater HMP deviation might have occured because these runners might have
loaded cartilage sub-regions which may have been less adapted to mechanical loads given that, habitually, they
may be less loaded than other regions of the knee. Loading less adapted cartilage areas has been considered to be
a risk factor for the progression of overuse injuries such as knee osteoarthritis23. Consequently, monitoring the
habitual motion path during well controllable weight-bearing activities such as walking, stair climbing, squatting
or sitting down or up from a chair might be an interesting approach to prevent the fast progression of overuse
type injuries at the knee.
Furthermore, the development and selection of technological aids such as footwear should consider the HMP
of their users. e reduced cartilage volume reduction on the medial tibia across footwear conditions found in
this study support this idea, even though the eect sizes induced across footwear were smaller than the eect sizes
observed between runners of dierent HMP deviation patterns. However, the footwear conditions in this study
might not have been ideal for minimizing or maximizing HMP deviation for individual participants. It is inter-
esting to note that dierent shoe conditions minimized or maximized the HMP deviation in individual runners.
is highlights the idea that an individual approach is needed to inform footwear assignment for runners which
is based on the HMP theory. Future studies need to explore the eects of technological interventions including
footwear in greater detail, which might result in a better understanding of the determinants of HMP deviation in
running or other more demanding types of locomotion.
We determined the HMP basleline from a two-leg half squat motion as described in our previous protocol
paper4. We used this motion, because it is a common every day task, similar to e.g. sitting down on a chair.
Further, it requires relatively small force generation and can be well controlled by the participants. erefore, we
believe that it is likely that the HMP can be kept by the participants during the two-leg squat. Furthermore, pilot
studies inidicated a good reliability of the two-leg squat motion, e.g. in comparison to a one-leg squat motion,
which might have the benet of being more similar to the actual running motion. Future studies should attempt
to nd a method to quantify the individual HMP which includes several common knee-exion tasks which likely
Figure 3. Comparison of HMP deviation amplitudes between the high and low HMP deviation groups
(le) and the high and low HMP deviation footwear conditions (right). Each dot on the le part of the graph
represents a dierent runner, while each runner is represented by a dierent line in the right part of the graph.
Bold horizontal lines indicate the mean value of a group of runners (le part) or the mean value of the high and
low HMP deviation footwear conditions, respectively (right part). In the bottom part eects sizes (Cohen’s d)
for between group and between footwear comparisons are highlighted.
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can be performed while staying within the HMP. is way, a more general and more robust quantication of the
HMP baseline might be obtained.
While this study provides new evidence in support of the HMP theory, several limitations need to be con-
sidered when interpreting the results. Due to the extensive cost of MRI measurements used in this study, we
were only able to include twelve participants in the study. is low sample size was a limiting factor concerning
the statistical power of the study. Despite the low sample size, we found several signicant dierences between
subject groups and footwear conditions. However, future studies should try to replicate our ndings with a larger
sample size in order to further understand the eects of personalized footwear. Next, we used treadmill running
to induce running specic loading of the knee joint articular cartilage. e major amount of distance running is
performed over ground. erefore, replication of our results should also consider the use of over ground running,
even though the running conditions are much more dicult to standardize in this situation.
Furthermore, we only collected biomechanical data of runners in an non-fatigued state. During a 75 minutes
running bout, running mechanics can change because of running-induced fatigue17,24. erefore, future studies
should consider fatigue eects when quantifying HMP deviation during prolonged runs.
Finally, measuring knee joint kinematics in the frontal and transverse plane from skin mounted markers is
a challenging tasks and is prone to measurement errors, like e.g. so tissue, skin movement or knee cross-talk
artefacts2527. In particular, the so tissue artefact is dependent upon the muscle activation level and impact char-
acteristics of the movement. Even though we used a mathematical optimization of marker trajectory data in our
calculations of the orientation and position of the anatomical coordinate systems, such that the coordinates better
comply with rigid body assumptions10,28, of the thigh and shank. However, it is not unlikely that some of the HMP
deviations calculated were actually caused by measurement errors and not related to actual bone motion dier-
ences. Future studies should address this issue by using more precise measurement technologies like e.g. biplanar
videoradiography29.
In summary, we found evidence in support of the HMP theory. Runners with a higher deviation from the
HMP baseline showed signicantly greater cartilage volume reductions in several knee joint cartilage sub-regions.
Furthermore, the cartilage on the medial tibial compartment showed greater cartilage volume reductions when
participants were running in footwear that induced higher HMP deviation. ese results indirectly indicate
higher mechanical loading on potentially less adapted sub-regions of the knee joint cartilage when runners devi-
ate more from their HMP baseline.
Data availability
All underlying data is made available upon request by the corresponding author of this study.
Received: 10 July 2019; Accepted: 8 January 2020;
Published: xx xx xxxx
References
1. oos, . G. & Marshall, S. W. Denition and Usage of the Term “Overuse Injury” in the US High School and Collegiate Sport
Epidemiology Literature: A Systematic eview. Sports Med. 44, 405–421 (2014).
2. van Gent, . N. et al. Incidence and determinants of lower extremity running injuries in long distance runners: a systematic review.
Br J Sports Med 41, 469–80; discussion 480 (2007).
3. Nigg, B. M., Baltich, J., Hoerzer, S. & Enders, H. unning shoes and running injuries: mythbusting and a proposal for two new
paradigms: ‘preferred movement path’ and ‘comfort filter’. Br. J. Sports Med. bjsports-2015-095054, https://doi.org/10.1136/
bjsports-2015-095054 (2015).
4. Trudeau, M. B. et al. A novel method for estimating an individual’s deviation from their habitual motion path when running.
Footwear Sci. 0, 1–11 (2019).
5. ram, . & Taylor, C. . Energetics of running: a new perspective. Nat. 346, 265–267 (1990).
6. Weyand, P. G., Sternlight, D. B., Bellizzi, M. J. & Wright, S. Faster top running speeds are achieved with greater ground forces not
more rapid leg movements. J. Appl. Physiol. 89, 1991–9 (2000).
7. Bramble, D. M. & Lieberman, D. E. Endurance running and the evolution of Homo. Nat. 432, 345–352 (2004).
8. Fischer, ., ohr, E., Hamill, J., Willwacher, S. & Brueggemann, P. Neuromuscular response to perturbation of the habitual joint
motion path in running. Footwear Sci. 5, S135–S136 (2013).
9. Fischer, ., Willwacher, S., Hamill, J., ohr, E. & Brueggemann, P. esponse of joint inematics and muscle activity to running on
tilted walways. Footwear Sci. 5, S89–S90 (2013).
10. Willwacher, S., Fischer, . M., Bener, ., Dill, S. & Brüggemann, G. inetics of cross-slope running. J. Biomech. 46, 2769–2777
(2013).
1 1. Boococ, M., McNair, P., Cicuttini, F., Stuart, A. & Sinclair, T. e short-term eects of running on the deformation of nee articular
cartilage and its relationship to biomechanical loads at the nee. Osteoarthr. Car til. 17, 883–890 (2009).
12. ersting, U. G., Stubendor, J. J., Schmidt, M. C. & Brüggemann, G.-P. Changes in nee cartilage volume and serum COMP
concentration aer running exercise. Osteoarthr. Cartil. 13, 925–934 (2005).
13. Nieho, A. et al. Deformational behaviour of nee cartilage and changes in serum cartilage oligomeric matrix protein (COMP) aer
running and drop landing. Osteoarthr. Cartil. 19, 1003–1010 (2011).
14. Wirth, W. & Ecstein, F. A Technique for egional Analysis of Femorotibial Cartilage icness Based on Quantitative Magnetic
esonance Imaging. IEEE Trans. Med. Imaging 27, 737–744 (2008).
15. Maly, M. . et al. nee adduction moment relates to medial femoral and tibial cartilage morphology in clinical nee osteoarthritis.
J. Biomech. 48, 3495–3501 (2015).
16. Fischer, . M., Willwacher, S., Hamill, J. & Brüggemann, G.-P. Tibial rotation in running: Does rearfoot adduction matter? Gait
Posture 51, 188–193 (2017).
17. Sanno, M., Willwacher, S., Epro, G. & Brüggemann, G.-P. Positive Wor Contribution Shis from Distal to Proximal Joints during a
Prolonged un. Med. Sci. Sports Exerc. 50, 2507–2517 (2018).
18. Willwacher, S., urz, M., Menne, C., Schrödter, E. & Brüggemann, G.-P. Biomechanical response to altered footwear longitudinal
bending stiness in the early acceleration phase of sprinting. Footwear Sci. 8, 99–108 (2016).
19. Willwacher, S. et al. Footwear eects on free moment application in running. Footwear Sci. 10, 57–68 (2018).
20. Ecstein, F., Mosher, T. & Hunter, D. Imaging of nee osteoarthritis: data beyond the beauty. Curr. Opin. Rheumatol. 19, 435–443
(2007).
Content courtesy of Springer Nature, terms of use apply. Rights reserved
7
SCIENTIFIC REPORTS | (2020) 10:1363 | https://doi.org/10.1038/s41598-020-58352-5
www.nature.com/scientificreports
www.nature.com/scientificreports/
21. Cohen, J. Statistical Power Analysis for the Behavioral Sciences. Lawrence Erlbaum Associates, Hillsdale, NJ (1988).
22. essler, M. A., Glaser, C., Tittel, S., eiser, M. & Imho, A. B. Volume Changes in the Menisci and Articular Cartilage of unners:
An in Vi vo Investigation Based on 3-D Magnetic esonance Imaging. Am. J. Sports Med. 34, 832–836 (2006).
23. Andriacchi, T. P. et al. A Framewor for the in Vivo Pathomechanics of Osteoarthritis at the nee. Ann. Biomed. Eng. 32, 447–457
(2004).
24. Weir, G. et al. e inuence of prolonged running and footwear on lower extremity biomechanics. Footwear Sci. 11, 1–11 (2019).
25. Cappozzo, A., Della Croce, U., Leardini, A. & Chiari, L. Human movement analysis using stereophotogrammetry: Part 1: theoretical
bacground. Gait Posture 21, 186–196 (2005).
26 . Chiari, L., Croce, U. D., Leardini, A. & Cappozzo, A. Human movement analysis using stereophotogrammetry: Part 2: Instrumental
errors. Gait Posture 21, 197–211 (2005).
27. Leardini, A., Chiari, L., Croce, U. D. & Cappozzo, A. Human movement analysis using stereophotogrammetry: Part 3. So tissue
artifact assessment and compensation. Gait Posture 21, 212–225 (2005).
2 8. Södervist, I. & Wedin, P.-Å. Determining the movements of the seleton using well-congured marers. J. Biomech. 26, 1473–1477
(1993).
29. Miranda, D. L., ainbow, M. J., Crisco, J. J. & Fleming, B. C. inematic dierences between optical motion capture and biplanar
videoradiography during a jump–cut maneuver. J. Biomech. 46, 567–573 (2013).
Acknowledgements
is work was partly funded through a grant from Brooks Running Inc., Seattle, WA, USA. We are grateful to the
help of Katina Fischer, Stephan Dill and Markus Kurz during data collection.
Author contributions
e study was designed by S.W., M.B.T., G.P.B., J.H. and G.B. S.W. wrote the paper with substantial contribution
from M.B.T., G.P.B., J.H., G.W. and G.B. Experimental data were collected by D.M., G.B. and S.W. Biomechanical
model calculations were performed by S.W. and D.M. MRI analyses were performed by G.B. Statistical analyses
were performed by S.W.
Competing interests
e authors declare no competing interests.
Additional information
Supplementary information is available for this paper at https://doi.org/10.1038/s41598-020-58352-5.
Correspondence and requests for materials should be addressed to S.W.
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... To our knowledge, no studies have directly tested the effect of matching footwear to minimize biomechanical variability and/or deviation from a specific motion path on running related injury. However, one study (Willwacher et al., 2020) suggested that increased time outside one's habitual motion path was associated with tissue-related changes in the knee joint. In this study of 12 healthy recreational runners, medial femur, medial tibia, and patella cartilage volume reductions were larger after 75 min of running in a shoe that increased a runner's deviation from their habitual joint path compared to one that reduced the deviation. ...
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... Ausgehend vom originären Konzept in Bezug auf die Reduzierung der Stoßkräfte (Dämpfung) sowie die Skelettausrichtung (mediolaterale Stabilität) wird ein "Muskel-Tuning-Konzept" (basierend auf der Muskelvibration), ein Konzept zum "Präferierten Bewegungspfad" sowie zu einem sogenannten Kom-Abb. 6 [56][57][58]. ...
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Objective: To quantify the magnitude of global rearfoot motion, in particular, rearfoot adduction and to investigate its relationship to tibial rotation. Design: One hundred and four participants ran barefoot on an Ethylene Vinyl Acetate (EVA) foam. Global range of motion values for the shank, rearfoot and medial metatarsal segment as well as foot motion within the transverse plane were determined using an optoelectric motion capture system. Relationships between parameters were assessed using partial correlation analysis. Results: Global rearfoot adduction amounts to 6.1° (±2.7). Furthermore global rearfoot adduction and rearfoot eversion were significantly related to internal tibial rotation (partial correlation: r=0.37, p<0.001 and r=-0.24, p=0.015, respectively). Furthermore, a strong relationship between rearfoot adduction and transverse within foot motion (r=-0.65, p<0.001) was found. Conclusion: Next to rearfoot eversion, rearfoot adduction may be also important to the understanding of ankle joint coupling. Controlling rearfoot adduction and transverse within foot motion may be a mechanism to control excessive tibial rotation.
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Longitudinal bending stiffness (LBS) of footwear has been shown to affect performance in jumping and sprinting tasks. A detailed description of the mechanisms underlying these performance alterations is lacking in the literature at the moment. Therefore, the purpose of this study is to describe why performance in a linear acceleration task is affected by LBS. Fifteen male athletes were analysed using full-body motion analysis combined with ground reaction force (GRF) measurements during the first step of a full effort 5 m sprint in a low stiffness baseline (BL), medium stiffness (MS) and high stiffness (HS) condition. A significant reduction in acceleration performance (−6.3%) was found in the HS condition compared to BL. Changes in acceleration performance in MS and HS were related to altered contact times, ground force application and overall body orientation, but not to alterations in energy absorption at the metatarsal phalangeal (MTP) joint. A gearing function of LBS was evident from increased MTP and ankle joint GRF lever arms, which might offer a potential to improve the effectiveness of horizontal force application. Nonetheless, athletes in this study were not using this potential to improve acceleration performance, possibly due to missing strength capacities. The results of this study indicate that high LBS might lead to reduced acceleration performance in athletes lacking the capacities to make use of the gearing function of footwear LBS. Footwear studies need to address the interrelationship between LBS, individual strength capacities, average ground force application and its effectiveness during acceleration tasks in the future.
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In the past 100 years, running shoes experienced dramatic changes. The question then arises whether or not running shoes (or sport shoes in general) influence the frequency of running injuries at all. This paper addresses five aspects related to running injuries and shoe selection, including (1) the changes in running injuries over the past 40 years, (2) the relationship between sport shoes, sport inserts and running injuries, (3) previously researched mechanisms of injury related to footwear and two new paradigms for injury prevention including (4) the 'preferred movement path' and (5) the 'comfort filter'. Specifically, the data regarding the relationship between impact characteristics and ankle pronation to the risk of developing a running-related injury is reviewed. Based on the lack of conclusive evidence for these two variables, which were once thought to be the prime predictors of running injuries, two new paradigms are suggested to elucidate the association between footwear and injury. These two paradigms, 'the preferred movement path' and 'the comfort filter', suggest that a runner intuitively selects a comfortable product using their own comfort filter that allows them to remain in the preferred movement path. This may automatically reduce the injury risk and may explain why there does not seem to be a secular trend in running injury rates. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.