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Greater vertical impact loading in female runners with medically diagnosed injuries: A prospective investigation
Abstract
Background Running has been critical to human survival. Therefore, the high rate of injuries experienced by modern day runners is puzzling. Landing on the heel, as most modern day shod runners do, results in a distinct vertical impact force that has been shown to be associated with running-related injuries. However, these injury studies were retrospective in nature and do not establish cause and effect.
Objective To determine whether runners with high impacts are at greater risk for developing medically diagnosed injuries.
Methods 249 female runners underwent a gait analysis to measure vertical instantaneous loading rate, vertical average loading rate (VALR), vertical impact peak (VIP) and peak vertical force. Participants then recorded their mileage and any running-related injuries monthly in a web-based, database programme. Variables were first compared between the entire injured (INJ; n=144) and uninjured (n=105) groups. However, the focus of this study was on those injured runners seeking medical attention (n=103) and those who had never injured (n=21).
Results There were no differences between the entire group of injured and uninjured groups. However, all impact-related variables were higher in those with medically diagnosed injuries compared with those who had never been injured. (effect size (ES) 0.4–0.59). When VALR was >66.0 body weight (BW)/s, the odds of being DX_INJ were 2.72 (95% CI 1.0 to 7.4). Impact loading was associated with bony and soft-tissue injuries.
Conclusions Vertical average loading rate was lower in female runners classified as ‘never injured’ compared with those who had been injured and sought medical attention.
... The gross motor J o u r n a l P r e -p r o o f function of children with CP can be classified using the Gross Motor Functional Classification Scale-Expanded and Revised (GMFCS E-R), which is an ordinal scale of five levels [3]. Children aged [6][7][8][9][10][11][12][13][14][15][16][17][18] years in GMFCS level I will be able to run with limited balance, speed and coordination, while twothirds of children in GMFCS level II are able to run [4]. Children classified as GMFCS levels III to V are not able to run independently due to their neurological disorders and motor disturbance [3]. ...
... Running barefoot is reported to have a higher VALR than shod running, especially if the barefoot runner has a rearfoot strike [15,16]. Increased VALR when running has been associated with lower limb stress fractures and plantar fasciitis [17,18]. Forefoot J o u r n a l P r e -p r o o f striking has also been associated with lower patellofemoral stress and increased peak ankle plantarflexion moment compared to rearfoot striking, which may imply a reduced risk of knee injury, but increased risk of foot and ankle injuries [19]. ...
... Since footwear did not appear to change foot strike pattern in GMFCS II, this suggests that for children with CP GMFCS level II, cadence and step length may be more important determinants of loading rate than the footwear itself. Higher loading rates in barefoot running when compared to shod are reported in neurotypical adults [33] and TD children [34] which is of clinical interest because of the association between increased loading rate and injuries such as tibial stress fractures and plantar fasciitis in adult recreational runners and athletes [17,18]. In neurotypical adults, higher cadence/shorter step length is associated with reduced ankle and knee joint excursion [35], increased leg stiffness [36], and increased loading rate [33], regardless of footwear condition. ...
Background
The biomechanics of barefoot and shod running are different for typically developing children but unknown for children with cerebral palsy (CP). Such differences may have implications for injury and performance.
Aims
The primary aims of this study were to compare the lower limb biomechanics of barefoot and shod running in children with CP, and to determine whether any differences were the same in GMFCS levels I and II.
Methods
This cross-sectional study examined 38 children with CP (n=24 (GMFCS) level I; n=14 GMFCS II), running overground at 3 speeds (jog, run, sprint) in barefoot and shod conditions. Marker trajectories and force plate data were recorded, and lower limb kinematics, kinetics and spatiotemporal variables were derived. Differences between barefoot and shod running were analysed using linear mixed models.
Results
For both GMFCS levels, barefoot running resulted in higher loading rates, but smaller impact peaks at all speeds. Barefoot running was associated with greater hip and knee power; less ankle dorsiflexion and hip flexion at initial contact, and less ankle and knee range of motion during stance, compared to shod running, at all speeds. Barefoot stride length was shortened, and cadence increased compared to shod during jogging and running but not sprinting. For GMFCS level I only, barefoot running involved a higher incidence of forefoot strike, greater ankle power generation and less hip range of motion during stance.
Significance
Running barefoot may facilitate running performance by increasing power generation at the ankle in children with CP, GMFCS level I. Higher barefoot loading rates may have implications for performance and injury.
... Impact-related variables may be surrogate measures of some of the loading that the lower limb experiences during gait and have been measured through force plates (Chan et al., 2017) and inertial measurement units (Crowell & Davis, 2011). While the development of running-related injuries is multifactorial (Edwards, 2018;Matijevich et al., 2019), impact loading-related variables, such as ground reaction forces (GRF) and peak tibial acceleration (PTA) metrics have been associated with an increased injury risk during running (Chan et al., 2017;Davis et al., 2016;Milner et al., 2006). Elevated PTA has been associated with a history of tibial stress fracture (Milner et al., 2006), and female runners with a greater vertical GRF average loading rate (>66 BW/s) were 2.7 times more likely to sustain an injury than those who had lower loading rates over a two-year period (Davis et al., 2016). ...
... While the development of running-related injuries is multifactorial (Edwards, 2018;Matijevich et al., 2019), impact loading-related variables, such as ground reaction forces (GRF) and peak tibial acceleration (PTA) metrics have been associated with an increased injury risk during running (Chan et al., 2017;Davis et al., 2016;Milner et al., 2006). Elevated PTA has been associated with a history of tibial stress fracture (Milner et al., 2006), and female runners with a greater vertical GRF average loading rate (>66 BW/s) were 2.7 times more likely to sustain an injury than those who had lower loading rates over a two-year period (Davis et al., 2016). Supporting the notion that impact loading is a risk factor for running-related injury development, Chan et al. (2017) showed that the incidence of running-related injuries over 1 year also reduced by 62% when runners undergo gait retraining to reduce their vertical GRFs by running "softly". ...
... This could be explained by peripheral muscle fatigue, where weakened, fatigued, or altered activation patterns may compromise the ability to attenuate impact loading through eccentric muscle contractions during early contact, leading to greater impact and strain imparted on the bone during landing (Avin et al., 2014;Burr, 2011;Warden et al., 2014) Investigations of the effects of prolonged running and fatigue on lower-limb biomechanics allow insight into the adaption techniques made by athletes to help with injury risk or performance during a run (Winter et al., 2017). Given the role of elevated impact loading in the aetiology of running-related injuries such as bone stress injury (Davis et al., 2016;Milner et al., 2006;Rice et al., 2019a) and the U-shaped relationship between variables such as leg-stiffness and running economy (Moore et al., 2019), understanding if fatigue is associated with changes to the biomechanics of running has important implications for both injury and performance. Multiple systematic reviews investigating biomechanical changes during running (Winter et al., 2017), biomechanical risk factors for runningrelated injury (Ceyssens et al., 2019) and biomechanical changes post-match in team sport athletes (Garrett et al., 2019) have been conducted. ...
This systematic review and meta-analysis aimed to synthesise and clarify the effect of running-induced fatigue on impact loading during running. Eight electronic databases were systematically searched until April 2021. Studies that analysed impact loading over the course of a run, in adult runners free of medical conditions were included. Changes in leg stiffness, vertical stiffness, shock attenuation, peak tibial accelerations, peak ground reaction forces (GRF) and loading rates were extracted. Subgroup analyses were conducted depending on whether participants were required to run to exhaustion. Thirty-six studies were included in the review, 25 were included in the meta-analysis. Leg stiffness decreased with running-induced fatigue (SMD -0.31, 95% CI -0.52, -0.08, moderate evidence). Exhaustive and non-exhaustive subgroups were different for peak tibial acceleration (Chi2 = 3.79, p = 0.05), with limited evidence from exhaustive subgroups showing an increase in peak tibial acceleration with fatigue. Findings for vertical GRF impact peak and peak braking force were conflicting based on exhaustive and non-exhaustive protocols (Chi2 = 3.83, p = 0.05 and Chi2 = 5.10, p = 0.02, respectively). Moderate evidence suggests leg stiffness during running decreases with fatigue. Given the non-linear relationship between leg stiffness and running economy, this may have implications for performance.
... However, one of the drawbacks is the high incidence of running-related injuries (RRI), such as patellofemoral pain syndrome, iliotibial band friction syndrome, plantar fasciitis, meniscal injuries and patellar tendinopathy (Van Gent et al., 2007;Kluitenberg et al., 2015). The etiology of RRI is believed to be multifactorial (Buist et al., 2010;van der Worp et al., 2015;Davis et al., 2017;Dudley et al., 2017) and is generally thought to include the following biomechanical risk factors: altered medial longitudinal arch (MLA) posture (Cowan et al., 1993;Busseuil et al., 1998;Bennett et al., 2001;Williams et al., 2001;Weist et al., 2004;Headlee et al., 2008;Kelly et al., 2015); greater ankle (Messier and Pittala, 1988;Willems et al., 2006;Pohl and Buckley, 2008) or rearfoot (Noehren et al., 2007(Noehren et al., , 2013Hein and Grau, 2014;Messier et al., 2018) eversion; and higher loading rates (Hreljac et al., 2000;Milner et al., 2005;Zadpoor and Nikooyan, 2011;Bredeweg et al., 2013;Davis et al., 2016), impact peaks (Bennell et al., 1996;Hreljac et al., 2000;Milner et al., 2005;Davis et al., 2016), and breaking forces (Grimston et al., 1991;Messier et al., 1995;Napier et al., 2018). ...
... However, one of the drawbacks is the high incidence of running-related injuries (RRI), such as patellofemoral pain syndrome, iliotibial band friction syndrome, plantar fasciitis, meniscal injuries and patellar tendinopathy (Van Gent et al., 2007;Kluitenberg et al., 2015). The etiology of RRI is believed to be multifactorial (Buist et al., 2010;van der Worp et al., 2015;Davis et al., 2017;Dudley et al., 2017) and is generally thought to include the following biomechanical risk factors: altered medial longitudinal arch (MLA) posture (Cowan et al., 1993;Busseuil et al., 1998;Bennett et al., 2001;Williams et al., 2001;Weist et al., 2004;Headlee et al., 2008;Kelly et al., 2015); greater ankle (Messier and Pittala, 1988;Willems et al., 2006;Pohl and Buckley, 2008) or rearfoot (Noehren et al., 2007(Noehren et al., , 2013Hein and Grau, 2014;Messier et al., 2018) eversion; and higher loading rates (Hreljac et al., 2000;Milner et al., 2005;Zadpoor and Nikooyan, 2011;Bredeweg et al., 2013;Davis et al., 2016), impact peaks (Bennell et al., 1996;Hreljac et al., 2000;Milner et al., 2005;Davis et al., 2016), and breaking forces (Grimston et al., 1991;Messier et al., 1995;Napier et al., 2018). ...
... A promising alternative strategy, the so-called "bottom-up" approach, targeted foot core muscles strength (intrinsic and extrinsic foot muscles) (McKeon and Fourchet, 2015a) and biomechanics with the goal of attenuating mechanical loads directly related to RRI (Milner et al., 2005;Warden et al., 2008;Davis et al., 2016). It applies the lumbopelvic core system concept to the foot core system. ...
This study investigated the effectiveness of an 8-week foot-core exercise training program on foot-ankle kinematics during running and also on running kinetics (impact loads), with particular interest in biomechanical outcomes considered risk factors for running-related injuries in recreational runners. A single-blind, randomized, controlled trial was conducted with 87 recreational runners randomly allocated to either the control (CG) or intervention (IG) group and assessed at baseline and after 8 weeks. The IG underwent foot-core training 3 times/week, while the CG followed a placebo lower-limb stretching protocol. The participants ran on a force-instrumented treadmill at a self-selected speed while foot-segment motion was captured simultaneously with kinetic measurements. After the intervention, there were statistically significant changed in foot biomechanics, such as: IG participants strike the ground with a more inverted calcaneus and a less dorsiflexed midfoot than those in the CG; at midstance, ran with a less plantarflexed and more adducted forefoot and a more abducted hallux; and at push-off, ran with a less dorsiflexed midfoot and a less adducted and more dorsiflexed hallux. The IG runners also had significantly decreased medial longitudinal arch excursion (p = 0.024) and increased rearfoot inversion (p = 0.037). The 8-week foot-core exercise program had no effect on impact (p = 0.129) and breaking forces (p = 0.934) or on vertical loading rate (p = 0.537), but it was positively effective in changing foot-ankle kinematic patterns.”
... Atypical lower limb alignment and biomechanical function are proposed to play a role in the development of lower limb injury [13], and may contribute to development of RRI. Previous investigations of biomechanical and musculoskeletal risk factors for RRI have included measures of muscle strength [14][15][16][17][18], joint range of motion (ROM) [4,16,19], lower limb alignment characteristics [4,16,17,20,21], plantar pressure analysis [22,23], running kinetics [16,24,25], and three-dimensional (3D) running kinematics [16,[26][27][28][29]. The findings of these studies have generally provided conflicting or inconclusive results. ...
... Five-hundred-and-six potentially relevant full texts were retrieved and screened (Fig. 1). Thirty articles [4,10,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][50][51][52][53][54][55][56][57][58][59][60][61] were included, while 476 were excluded based on the stated criteria (Additional file 1). ...
... [16, 24-26, 28, 29, 57, 58]. Five studies reported significant risk factors for RRI [16,24,25,29,58]. Napier et al. found peak braking force (PBF) to be a significant predictor of low-back or lower extremity RRI, reporting that runners in the highest PBF tertile (< − 0.27) become injured at 5.08 times those in the middle PBF (− 0.27 to 0.23) (HR 5.08, 95% CI 1.71 to 15.03, p = 0.003) tertile and 7.98 times those in the lowest tertile (> − 0.23) (HR 9.98, 95% CI 2.08 to 30.51, p = 0.002) [25]. ...
Background
Running-related injury (RRI) is highly prevalent among recreational runners and is a key barrier to participation. Atypical lower limb alignment and mechanical function have been proposed to play a role in development of lower extremity injury. The purpose of this study was to investigate relationships between incidence of running-related injury (RRI) in non-elite runners with biomechanical and musculoskeletal variables.
Methods
A systematic review and meta-analysis of prospective studies. Published research indexed in MEDLINE, EMBASE, CINAHL, SPORTDiscus, AMED, and The Cochrane library until 13th January 2021, grey literature, and reference lists of included studies were screened to identify prospective studies of non-elite adult runners that measured a relationship between biomechanical or musculoskeletal measures and incidence of RRI.
Results
Thirty studies (3404 runners), testing over 100 discrete biomechanical and musculoskeletal risk factors for RRI, were included. Nineteen studies were pooled in twenty-five separate meta-analyses. Meta-analysis of four studies detected significantly less knee extension strength among runners who developed a RRI (SMD − 0.19, 95% CI − 0.36 to − 0.02, p = 0.03), though this may not be clinically important. A meta-analysis of two studies detected significantly lower hip adduction velocity among runners who developed a RRI (MD − 12.80, 95% CI − 25.22 to − 0.38, p = 0.04). Remaining meta-analyses found no significant relationship between biomechanical or musculoskeletal variables and RRI.
Conclusion
This systematic review and meta-analysis found the currently available literature does not generally support biomechanical or musculoskeletal measures as risk factors for RRI in non-elite runners. While meta-analysis findings for knee extension strength and hip adduction velocity as risk factors for RRI were statistically significant, the associated trivial to small effects sizes suggest these findings should be treated with caution. Until further evidence emerges, recommendations for injury prevention in non-elite runners cannot be made based on biomechanical and musculoskeletal measurements alone.
... High vertical loading rates of the GRF are associated with tibial stress fracture injuries retrospectively 23 and prospectively. 24 High free moment of the GRF is also associated with tibial stress fracture injury history. 23 Interventions to mitigate localized muscle fatigue may also prevent gait modifications that are potentially injurious, such as increases in loading rates and free moments, as fatigue-induced changes in running mechanics are often considered to be an injury risk factor during prolonged running. ...
... The variables of interest are the vertical average loading rate (VALR) of the GRF and free moment of the GRF (free moment). 23,24 Muscle force production was assessed by maximal countermovement jump height (jump height), as neuromuscular fatigue caused a decrease in jump height in both short-and longterm fatigue. 27,28 Because of positive effects of roller massage on athletic performance, we hypothesized that roller massage prior to running would mitigate fatigue-related increases in VALR and free moment and mitigate fatigue-related decreases in muscle force production. ...
... VALR was calculated as the average slope of the vertical GRF between 20% and 80% of the time from initial contact to impact peak and scaled by body weight (BW). 24 When no impact peak was present, 13% of stance was used as a surrogate point of impact peak to calculate loading rate. 37 Free moment was scaled by BW and height (BW × Ht), and the peak absolute value during stance was determined. ...
Context:
Understanding if roller massage prior to a run can mitigate fatigue-related decrements in muscle force production during prolonged running is important because of the association between fatigue and running-related injury.
Objective:
The authors investigated whether a bout of roller massage prior to running would (1) mitigate fatigue-related increases in vertical average load rate and free moment of the ground reaction force of running and (2) mitigate decreases in maximal countermovement jump height.
Design:
Repeated-measures study.
Setting:
Laboratory.
Participants:
A total of 14 recreational endurance athletes (11 men and 3 women) volunteered for the study.
Interventions:
A 12.5-minute foam roller protocol for the lower extremities and a fatiguing 30-minute treadmill run.
Main outcome measures:
Vertical average load rate, free moment, and maximal jump height before (PRE) and after (POST) the fatiguing treadmill run on separate experimental days: once where participants sat quietly prior to the fatiguing run (REST) and another where the foam roller protocol was performed prior to the run (ROLL).
Results:
A 2-way multiple analysis of variance found no significant differences in vertical average load rate, free moment, and jump height between PRE/POST times in both REST/ROLL conditions.
Conclusions:
The authors concluded that recreational endurance athletes maintain running mechanics and jump performance after a fatiguing run regardless of prerun roller massage and may not rely on prerun roller massage as a form of injury prevention.
... One potential reason for the limited empirical evidence and understanding of the etiology of RRIs, and the ensuing difficulty in preventing them, may lie in the paradigms that are typically used in studying these risk factors (Bolling et al., 2018;Wiese-Bjornstal, 2018; see also Bittencourt et al., 2016). Contemporary paradigms in studies focusing on risk factors of RRIs include biomechanics (e.g., Ceyssens et al., 2019;Bertelsen et al., 2017;Napier et al., 2018;Davis et al., 2016;Fields et al., 2010), exercise physiology (e.g., Baltich et al., 2016;Ramskov et al., 2018;Hespanhol et al., 2018), evolutionary biology and adaptation (e.g., Lieberman, 2020), and others such as anthropometrics and (socio-)demographics (e.g., van Poppel et al., 2020, Yeung et al., 2011. We emphasize that these perspectives are well-documented and important for understanding why RRIs occur. ...
... This contribution connects to one of our original reasons for taking this specific psychological direction: the pattern of research on health outcomes of running relying heavily on more physiological and biomechanical perspectives while foregoing the psychological factors that may play a role. Fortunately, in addition to these valuable physiological and biomechanical perspectives (e.g., Hespanhol et al., 2018;Davis et al., 2016;Fields et al., 2010), there is a visible upward trend in research investigating psychological matters (e.g., Mousavi et al., 2021;Balk, 2018;Martin et al., 2021). As we join this trend (see also Ángel et al., 2021), building on insights from work, sport, and (occupational) health psychology, we identified relevant psychological factors that were linked to injuries and other health outcomes of runners. ...
This dissertation discusses whether specific psychological factors contribute to our ability to understand and optimize the health outcomes of running. It provides information on coping, psychological risk profiles, an app intervention, and a self-assessment tool to determine one's risk for adverse health outcomes as a runner.
... Virtual joint center markers were calculated for each static trial as follows: Hip joint center by regression equation defined by Harrington et al. (2007) [13] and knee, ankle, and forefoot joints center by averaging the medial and lateral epicondyle, malleolus, and metatarsal head markers, respectively. GRF data were low-pass filtered using zero-lag fourth-order Butterworth at a cut-off frequency of 50 Hz [14,15]. ...
... Visual inspection of vertical GRF (Fig 3) also shows decreased time to impact peak in boot condition which is not surprising for the less cushioned footwear and it is in agreement with previous studies [10]. Literature found that the time to peak is more important than the magnitude of the peak itself in running injuries [14,32]. Greater variability in the medial-lateral component of GRF existed that has been noted previously [26] and there were also non-significant less breaking and propulsion peaks of the anterior-posterior component of GRF in the boot condition. ...
Boots are often used in sports, occupations, and rehabilitation. However, there are few studies on the biomechanical alterations after wearing boots. The current study aimed to compare the effects of running shoes and boots on running biomechanics. Kinematics and ground reaction forces were recorded from 17 healthy males during running at 3.3 m/s with shoe and boot conditions. Temporal distance gait variables, ground reaction force components as well as lower limb joints angle, moment, and power were compared using Paired t-test and Statistical Parametric Mapping package for time-series analysis. Running with boots was associated with greater stride, step, flight, and swing times, greater flight length, and smaller cadence ( p <0.05). The only effect of boots on lower limb joints kinematics during running was a reduction in ankle range of motion ( p <0.05). Significantly greater hip flexor, abductor, and internal rotator moments, greater knee extensor and abductor moments, and ankle plantar flexor moments were observed at push-off phase of running as well as greater ankle dorsiflexor moment at early-stance in boot condition ( p <0.05). Also, knee joint positive power was greater with a significant temporal shift in boot condition, suggesting a compensatory mechanism in response to limited ankle range of motion and the inability of the ankle joint to generate the required power. Our findings showed that running with boots is physically more demanding and is associated with a greater net contribution of muscles spanning hip and knee joints in order to generate more power and compensate for the ankle joint limitations, consequently, may increase the risk of both musculoskeletal injuries and degenerative joint diseases.
... Some data suggest that vertical impact peak and loading rate are related to running-related injury risk. 6,7,38 However, these observations were mainly based on crosssectional studies, had limited sample sizes, and mostly focused on tibial stress fracture as the injury outcome. Peak braking force was associated with a higher injury risk in healthy female recreational runners engaged in a 15-week half-marathon training and was therefore suggested as a target for gait retraining interventions. ...
... A previous prospective study investigated impact forces as a potential injury risk factor in female runners. 7 Although no difference was observed between injured and uninjured runners, secondary analyses showed that vertical impact peak and loading rates were greater in runners with a medically diagnosed injury compared with those who had never reported any previous injury. However, these results were based on a small sample size (N = 32 in total), and the analysis was retrospective in nature, which limits the conclusions that can be drawn. ...
Background
Running biomechanics may play a role in running-related injury development, but to date, only a few modifiable factors have been prospectively associated with injury risk.
Purpose
To identify risk factors among spatiotemporal and ground-reaction force characteristics in recreational runners and to investigate whether shoe cushioning modifies the association between running biomechanics and injury risk.
Study Design
Case-control study; Level of evidence, 3.
Methods
Recreational runners (N = 848) were tested on an instrumented treadmill at their preferred running speed in randomly allocated, standardized running shoes (with either hard or soft cushioning). Typical kinetic and spatiotemporal metrics were derived from ground-reaction force recordings. Participants were subsequently followed up for 6 months regarding running activity and injury. Cox regression models for competing risk were used to investigate the association between biomechanical risk factors and injury risk, including stratified analyses by shoe version.
Results
In the crude analysis, greater injury risk was found for greater step length (subhazard rate ratio [SHR], 1.01; 95% CI, 1.00-1.02; P = .038), longer flight time (SHR, 1.00; 95% CI, 1.00-1.01; P = .028), shorter contact time (SHR, 0.99; 95% CI, 0.99-1.00; P = .030), and lower duty factor (defined as the ratio between contact time and stride time; SHR, 0.95; 95% CI, 0.91-0.98; P = .005). In the stratified analyses by shoe version, adjusted for previous injury and running speed, lower duty factor was associated with greater injury risk in those using the soft shoes (SHR, 0.92; 95% CI, 0.85-0.99; P = .042) but not in those using the hard shoes (SHR, 0.97; 95% CI, 0.91-1.04; P = .348).
Conclusion
Lower duty factor is an injury risk factor, especially for softer shoe use. Contrary to widespread beliefs, vertical impact peak, loading rate, and step rate were not injury risk factors in recreational runners.
Registration
NCT03115437 (ClinicalTrials.gov identifier).
... In the past decade, many researchers have focused on investigating impact loading during running as represented by the magnitude and shape of the ground reaction force [15][16][17][18][19][20][21]. In particular, high vertical loading rates have been associated with bony and soft tissue injuries in runners [20]. ...
... In the past decade, many researchers have focused on investigating impact loading during running as represented by the magnitude and shape of the ground reaction force [15][16][17][18][19][20][21]. In particular, high vertical loading rates have been associated with bony and soft tissue injuries in runners [20]. Previous studies on adults and adolescents showed that the type of footwear and footstrike pattern could affect impact loading of the lower limb during running [16,17,19,[22][23][24]. ...
Background
Previous research indicated that running barefoot or in minimalist shoes led to lower impact loading in an adolescent and adult population. Running as fundamental locomotor skill significantly develops during early childhood (preschool age). However, no study has focused on effect of footwear condition on lower limb impact loading during running in this age. Therefore, the purpose of this study was to assess effect of footwear conditions (barefoot, minimalist and standard running shoes) on running impact loading in the preschool years.
Methods
Fourty-eight habitually shod preschool children were divided into 4 age groups. Children performed simple running game in 3 different footwear conditions (random counter-balanced order), 3-dimensional biomechanical analysis were carried out during overground running. The key dependent variables included vertical ground reaction force (VGRF) and vertical instantaneous loading rate (VILR). Statistical parametric mapping was performed to reveal possible differences in VGRF and one-way repeated measures ANOVA in VILR.
Results
Three-year-old children displayed significantly lower impact peak of VGRF in barefoot condition compared to minimalist (3-7% stance, P = 0.012) and standard running shoes (7-11% stance, P = 0.009). Furthermore, in 3-year-old in minimalist shoes had higher loading than in standard running shoes (0-4% stance, P = 0.007). There were also differences in VILR, where 3-year-old had lower loading in barefoot than in minimalist (P = 0.010, d = 1.19) or standard running shoes (P = 0.045, d = 0.98). No differences were found in older children.
Conclusion
Running in minimalist shoes did not imitate barefoot running and did not lower impact forces compared to standard running shoes in 3-year-old children. On the contrary, increased loading was observed in minimalist shoes in early running developmental stages. Professionals who work with children should consider effect of minimalist shoes on impact loading (running on hard surfaces).
... While loading forms a necessary component of training, resulting in homeostatic-positive responses and adaptations, 9,65 excessive cumulative load and a poor work-recovery ratio may result in maladaptation to training and an increased risk of injury. 17,56 Based on the excessive load that some FSPs may produce and the potential for this cumulative load to become injurious over time, 8,12,33 some researchers have suggested that FST, especially an RFS pattern, may be causative of RRIs. 11,25 While this may be intuitive, a direct relationship needs to be established. ...
... Scoring of the quality assessment is detailed in Appendix Table A5 (available online). The mean score for the 19item risk of bias assessment was 11.1 (range, [11][12][13][14][15][16][17]. Two studies had a moderate risk of bias, 15,23 and 11 studies had a low risk. ...
Background
It has been suggested that foot strike technique (FST) at initial contact is related to running-related injuries (RRIs).
Purpose
To explore the relationship between FST and RRIs.
Study Design
Systematic review; Level of evidence, 3.
Methods
A systematic electronic search was performed using MEDLINE, PubMed, SPORTDiscus, Scopus, and Web of Science databases. Included were studies published in the English language that explored the relationship between FST and RRIs between January 1960 and November 2020. Results were extracted and collated. The Grading of Recommendations, Assessment, Development and Evaluation approach was applied to synthesize the quality of evidence.
Results
We reviewed 13 studies exploring the relationship between FST and RRIs. Of these, 6 studies reported FST categorically (foot strike pattern [FSP]), and 7 reported continuous measures (foot contact angle, ankle flexion angle, and strike index). Three of the 6 studies looking at categorical FSP found rearfoot strikers have a significantly greater retrospective injury rate than do non– rearfoot strikers, with 1 other study noting a greater risk associated with midfoot and forefoot strike. Regarding the continuous measures of FST, only 1 of the 7 studies reported a significant relationship with RRIs.
Conclusion
There was low evidence to suggest a relationship between FST (or its subcategories of categorical FSP and continuous measures) and RRIs. While two-thirds of the categorical studies found a relationship between FSP and RRIs, these studies were very low quality, with limitations such as retrospective study design, low participant numbers, and poor FSP assessment methods. More large-scale prospective studies are required.
... An example of using biomechanical data to assess performance can be found in gait re-training, which is a relevant method to prevent running-related injuries through modifications in running technique [21,22]. It has been widely shown that vertical impact loading is associated with some types of running-related injuries, such as stress fractures [21,23,24], patellofemoral pain, and plantar fasciitis [25]. Running coaches can teach novice runners to minimize their impact forces by listening to the sounds runners produce [26]. ...
Accelerometry is becoming a popular method to access human movement in outdoor conditions. Running smartwatches may acquire chest accelerometry through a chest strap, but little is known about whether the data from these chest straps can provide indirect access to changes in vertical impact properties that define rearfoot or forefoot strike. This study assessed whether the data from a fitness smartwatch and chest strap containing a tri-axial accelerometer (FS) is sensible to detect changes in running style. Twenty-eight participants performed 95 m running bouts at ~3 m/s in two conditions: normal running and running while actively reducing impact sounds (silent running). The FS acquired running cadence, ground contact time (GCT), stride length, trunk vertical oscillation (TVO), and heart rate. Moreover, a tri-axial accelerometer attached to the right shank provided peak vertical tibia acceleration (PKACC). The running parameters extracted from the FS and PKACC variables were compared between normal and silent running. Moreover, the association between PKACC and smartwatch running parameters was accessed using Pearson correlations. There was a 13 ± 19% reduction in PKACC (p < 0.005), and a 5 ± 10% increase in TVO from normal to silent running (p < 0.01). Moreover, there were slight reductions (~2 ± 2%) in cadence and GCT when silently running (p < 0.05). However, there were no significant associations between PKACC and the variables extracted from the FS (r < 0.1, p > 0.05). Therefore, our results suggest that biomechanical variables extracted from FS have limited sensitivity to detect changes in running technique. Moreover, the biomechanical variables from the FS cannot be associated with lower limb vertical loading.
... Due to the abrupt nature of this rise in a RFS pattern, vertical load rate is significantly higher in a RFS than an FFS pattern [17,29]. An increased load rate have been associated with a variety of running-related injuries [19,20,30]. It is likely that it is discomfort or pain from this impact force that promotes an FFS pattern in barefoot runners. ...
... Impact loading is measured by the peak ground reaction force (GRF) or the loading rate, which is calculated by dividing the peak GRF by the time to peak GRF [4][5][6]. Recently, the loading rate has received more attention than peak GRF as an indicator of impact loading [7,8]. To reduce sports injuries, it is necessary to identify the physical functions related to the loading rate. ...
Background
Sports injuries are strongly associated with the impact loading at landing. The abilities to produce force and adjust timing are simultaneously required to absorb impact loading.
Aims
Hence, we aimed to examine the hypothesis that the ability to produce an explosive force at the right timing is related to the ability to absorb the impact loading at landing.
Methods
Twenty-nine healthy young men volunteered to participate in the study. We proposed a new test to measure the rate of force development (RFD) in accordance with the countdown signal. To evaluate the ability to produce explosive force at the right time, we measured the rate of change between the RFD at the standard start signal and the RFD at the countdown signal. Furthermore, to evaluate the ability to land from a jump, we measured the loading rate at single-leg drop landing (20 cm).
Results
We divided the participants into two groups based on the timing effect: the positive group (participants with increased RFD at the countdown signal, n = 11) and the negative group (participants with decreased RFD at the countdown signal, n = 18). The loading rate was significantly greater ( P < .01) in the negative group (47.4 ± 11.2 body weight (BW)/s) than in the positive group (34.7 ± 7.1 BW/s).
Conclusions
Participants with increased RFD at the countdown signal had a lower loading rate at landing. Our results suggest that the ability to produce a timely explosive force may be a determinant of safe landing ability.
... Running is an exercise widely known for the cumulative vertical loading that might induce acute and chronic lower limb injuries such as tibial stress fractures [5,6], tendinopathies and other musculoskeletal disorders at the lower limb and trunk [7][8][9][10]. Multiple studies have shown that assessing the changes in impact loading during running can be useful for preventing and/or reducing injury incidence accessible through variables such as vertical tibial acceleration and the vertical instantaneous loading rates [6,8,11]. Greater instantaneous impact loading may generate louder sounds of footsteps, which have been previously shown to be moderately correlated to vertical loading rates and peak propulsion forces [12,13]. ...
From the point of view of measurement, footstep sounds represent a simple, wearable and inexpensive sensing opportunity to assess running biomechanical parameters. Therefore, the aim of this study was to investigate whether the sounds of footsteps can be used to predict the vertical ground reaction force profiles during running. Thirty-seven recreational runners performed overground running, and their sounds of footsteps were recorded from four microphones, while the vertical ground reaction force was recorded using a force plate. We generated nine different combinations of microphone data, ranging from individual recordings up to all four microphones combined. We trained machine learning models using these microphone combinations and predicted the ground reaction force profiles by a leave-one-out approach on the subject level. There were no significant differences in the prediction accuracy between the different microphone combinations (p < 0.05). Moreover, the machine learning model was able to predict the ground reaction force profiles with a mean Pearson correlation coefficient of 0.99 (range 0.79–0.999), mean relative root-mean-square error of 9.96% (range 2–23%) and mean accuracy to define rearfoot or forefoot strike of 77%. Our results demonstrate the feasibility of using the sounds of footsteps in combination with machine learning algorithms based on Fourier transforms to predict the ground reaction force curves. The results are encouraging in terms of the opportunity to create wearable technology to assess the ground reaction force profiles for runners in the interests of injury prevention and performance optimization.
... The 15% limit was chosen because an impact peak was not always identified and so that the loading rate of every runner was in the same relative temporal window (Willson et al., 2014). The braking (LR brake ) and propulsive (LR prop ) loading rates, because of their relation to running-related injuries (Daoud et al., 2012;Willson et al., 2014;Davis et al., 2016;Johnson et al., 2020), were calculated as the largest slopes of the fore-aft ground reaction force signal between foot-strike and the instant of F brake,min and between mid-stance and the instant of F prop,max , respectively. ...
Duty factor (DF) and step frequency (SF) were previously defined as the key running pattern determinants. Hence, this study aimed to investigate the association of DF and SF on 1) the vertical and fore-aft ground reaction force signals using statistical parametric mapping; 2) the force related variables (peaks, loading rates, impulses); and 3) the spring-mass characteristics of the lower limb, assessed by computing the force-length relationship and leg stiffness, for treadmill runs at several endurance running speeds. One hundred and fifteen runners ran at 9, 11, and 13 km/h. Force data (1000 Hz) and whole-body three-dimensional kinematics (200 Hz) were acquired by an instrumented treadmill and optoelectronic system, respectively. Both lower DF and SF led to larger vertical and fore-aft ground reaction force fluctuations, but to a lower extent for SF than for DF. Besides, the linearity of the force-length relationship during the leg compression decreased with increasing DF or with decreasing SF but did not change during the leg decompression. These findings showed that the lower the DF and the higher the SF, the more the runner relies on the optimization of the spring-mass model, whereas the higher the DF and the lower the SF, the more the runner promotes forward propulsion.
... 10 Additionally, runners with a history of lower extremity injuries have been found to present with increased vertical impact peaks and average loading rates. 11 Although gaittraining programmes targeting these factors have been successful, 12 these interventions have been primarily limited to indoor settings among healthy runners. While several studies have implemented outdoor gait training for healthy runners and runners with tibial stress fractures, 13 14 more evidence is necessary to support our understanding of treatment success among runners actively experiencing lower limb pain in natural running environments. ...
Objectives
To assess the effects of a 4-week randomised controlled trial comparing an outdoor gait-training programme to reduce contact time in conjunction with home exercises (contact time gait-training feedback with home exercises (FBHE)) to home exercises (HEs) alone for runners with exercise-related lower leg pain on sensor-derived biomechanics and patient-reported outcomes.
Design
Randomised controlled trial.
Setting
Laboratory and field-based study.
Participants
20 runners with exercise-related lower leg pain were randomly allocated into FBHE (4 male (M), 6 female (F), 23±4 years, 22.0±4.3 kg/m ² ) or HE groups (3 M, 7 F, 25±5 years, 23.6±3.9 kg/m ² ).
Interventions
Both groups completed eight sessions of HEs over 4 weeks. The FBHE group received vibrotactile feedback through wearable sensors to reduce contact time during outdoor running.
Primary and secondary outcome measures
Patient-reported outcome measures (PROMs) and outdoor gait assessments were conducted for both groups at baseline and 4 weeks. PROMs were repeated at 6 weeks, and feedback retention was assessed at 6 weeks for the FBHE group. Repeated measures analyses of variance were used to assess the influence of group and timepoint on primary outcomes.
Results
The FBHE group reported increased function and recovery on PROMs beyond the HE group at 6 weeks (p<0.001). There was a significant group by time interaction for Global Rating of Change (p=0.004) and contact time (p=0.002); the FBHE group reported greater subjective improvement and reduced contact time at 4 and 6 weeks compared with the HE group and compared with baseline. The FBHE group had increased cadence (mean difference: 7 steps/min, p=0.01) at 4 weeks during outdoor running compared with baseline.
Conclusion
FBHE was more effective than HE alone for runners with exercise-related lower leg pain, manifested with improved PROMs, reduced contact time and increased cadence.
Trial registration number
NCT04270565 .
... Thirty consecutive strides were extracted for analysis. Twelve variables ( Table 3) that have been previously linked to sustaining RRIs 17,19,20,31,32 were extracted from the data. To account for the fact that speed was uncontrolled, residuals from a linear regression between speed and each variable were used for further analysis. ...
Running is a popular form of physical activity with a high incidence of running‐related injuries. However, the etiology of running‐related injuries remains elusive, possibly due to the heterogeneity of movement patterns. The purpose of this study was to investigate whether different clusters existed within a large group of injured and uninjured runners based on their kinetic gait patterns. A sample of 134 injured and uninjured runners were acquired from an existing database and 12 discrete kinetic and spatiotemporal variables which are commonly associated with running injury were extracted from the ground reaction force waveforms. A principal components analysis followed by an unsupervised hierarchical cluster analysis was performed. The results revealed two distinct clusters of runners which were not associated with injury status (OR = 1.14 [0.57, 2.30], X2 = 0.143, p = 0.706) or sex (OR = 1.72 [0.85, 3.49], X2 = 2.3258, p = 0.127). These results suggest that while there appeared to be evidence for two distinct clusters within a large sample of injured and uninjured runners, there is no association between the kinetic variables and running related injuries.
... Multiple loading-related variables have been prospectively linked to the occurrence of injuries. Amongst those variables is the vertical instantaneous loading rate (VILR) of the ground reaction force (GRF)62 . The GRFs during running represent the total acceleration of the body's center of mass (BCOM) and are, according to Newton's second law, responsive to the accelerations of all body segments91,162 . ...
... The relationship between vertical ground reaction forces and running-related injury has been extensively researched, with vertical loading rate reported to have the most consistent association with injury [62][63][64]. Pooled data from this review provide limited evidence that increasing step rate does not change peak vertical ground reaction force, average vertical loading rate, and vertical instantaneous loading rate [1,5,10,11]. These findings were consistent across multiple single studies and included step rate increases from 5 to 30%. ...
Background
Running-related injuries are prevalent among distance runners. Changing step rate is a commonly used running retraining strategy in the management and prevention of running-related injuries.
Objective
The aims of this review were to synthesise the evidence relating to the effects of changing running step rate on injury, performance and biomechanics.
Design
Systematic review and meta-analysis.
Data Sources
MEDLINE, EMBASE, CINAHL, and SPORTDiscus.
Results
Thirty-seven studies were included that related to injury ( n = 2), performance ( n = 5), and biomechanics ( n = 36). Regarding injury, very limited evidence indicated that increasing running step rate is associated with improvements in pain (4 weeks: standard mean difference (SMD), 95% CI 2.68, 1.52 to 3.83; 12 weeks: 3.62, 2.24 to 4.99) and function (4 weeks: 2.31, 3.39 to 1.24); 12 weeks: 3.42, 4.75 to 2.09) in recreational runners with patellofemoral pain. Regarding performance, very limited evidence indicated that increasing step rate increases perceived exertion ( − 0.49, − 0.91 to − 0.07) and awkwardness (− 0.72, − 1.38 to − 0.06) and effort (− 0.69, − 1.34, − 0.03); and very limited evidence that an increase in preferred step rate is associated with increased metabolic energy consumption (− 0.84, − 1.57 to − 0.11). Regarding biomechanics, increasing running step rate was associated with strong evidence of reduced peak knee flexion angle (0.66, 0.40 to 0.92); moderate evidence of reduced step length (0.93, 0.49 to 1.37), peak hip adduction (0.40, 0.11 to 0.69), and peak knee extensor moment (0.50, 0.18 to 0.81); moderate evidence of reduced foot strike angle (0.62, 034 to 0.90); limited evidence of reduced braking impulse (0.64, 0.29 to 1.00), peak hip flexion (0.42, 0.10 to 0.75), and peak patellofemoral joint stress (0.56, 0.07 to 1.05); and limited evidence of reduced negative hip (0.55, 0.20 to 0.91) and knee work (0.84, 0.48 to 1.20). Decreasing running step rate was associated with moderate evidence of increased step length (− 0.76, − 1.31 to − 0.21); limited evidence of increased contact time (− 0.95, − 1.49 to − 0.40), braking impulse (− 0.73, − 1.08 to − 0.37), and negative knee work (− 0.88, − 1.25 to − 0.52); and limited evidence of reduced negative ankle work (0.38, 0.03 to 0.73) and negative hip work (0.49, 0.07 to 0.91).
Conclusion
In general, increasing running step rate results in a reduction (or no change), and reducing step rate results in an increase (or no change), to kinetic, kinematic, and loading rate variables at the ankle, knee and hip. At present there is insufficient evidence to conclusively determine the effects of altering running step rate on injury and performance. As most studies included in this review investigated the immediate effects of changing running step rate, the longer-term effects remain largely unknown.
Prospero Registration
CRD42020167657.
... Impact loading is measured by the peak ground reaction force (GRF) or the loading rate, which is calculated by dividing the peak GRF by the time to peak GRF [2,3]. In recent years, the loading rate has received more attention than peak GRF as an indicator of impact loading [4,5]. In order to reduce sports injuries, it is necessary to identify the physical functions related to the loading rate. ...
Background
Sports injuries are strongly associated with the impact loading at landing. The ability to produce force and adjust the timing are simultaneously required for absorbing the impact loading.
Aims
Hence, we aimed to examine the hypothesis that the ability to produce explosive force at the right timing is related to the ability to absorb the impact loading at landing.
Methods
Twenty-nine healthy young men volunteered to participate in the study. We proposed a new test to measure the rate of force development (RFD) in accordance with the countdown signal. To evaluate the ability to produce explosive force at the right time, we measured the rate of change between the RFD at the standard start signal and the RFD at the countdown signal. Furthermore, to evaluate the ability to land from a jump, we measured the loading rate at single-leg drop landing (20 cm).
Results
We divided the participants into two groups based on the timing effect: the positive group (participants with increased RFD at the countdown signal, n = 11) and the negative group (participants with decreased RFD at the countdown signal, n = 18). The loading rate was significantly greater (P < .01) in the negative group (47.4 ± 11.2 body weight (BW)/s) than in the positive group (34.7 ± 7.1 BW/s).
Conclusions
Participants with increased RFD at the countdown signal had a lower loading rate at landing. Our results suggest that the ability to produce a timely explosive force may be a determinant of safe landing ability.
... Bilateral asymmetry, which relates to differences between the left and right lower limbs, has been suggested as a risk factor for RRI's based on the premise that because one leg is subjected to more loading, it is predisposed to injury [70,71]. Again the literature is contrasting, with some studies finding significant limb asymmetries in injured runners both retrospectively [72] and prospectively [73] compared to uninjured runners, while some studies report no differences in asymmetry [70,74]. No systematic review drawing an overall conclusion has been published to date. ...
Purpose:
Understanding the perceived efficacy and ease of use of technologies will influence initial adoption and sustained utilization. The objectives of this study were to determine the metrics deemed important by runners for monitoring running-related injury (RRI) risk, and identify the facilitators and barriers to their use of injury focused wearable technologies.
Methods:
A qualitative focus group study was undertaken. Nine semi-structured focus groups with male (n = 13) and female (n = 14) recreational runners took place. Focus groups were audio and video recorded, and transcribed verbatim. Transcripts were thematically analysed. A critical friend approach was taken to data coding, and multiple methods of trustworthiness were executed.
Results:
Excessive loading and inadequate recovery were deemed the most important risk factors to monitor for RRI risk. Other important factors included training activities, injury status and history, and running technique. The location and method of attachment of a wearable device, the design of a smartphone application, and receiving useful injury-related information will affect recreational runners' adoption of injury focused technologies.
Conclusions:
Overtraining, training-related and individual-related risk factors are essential metrics that need to be monitored for RRI risk. RRI apps should include the metrics deemed important by runners, once there is supporting evidence-based research. The difficulty and/or ease of use of a device, and receiving useful feedback will influence the adoption of injury focused running technologies. There is a clear willingness from recreational runners to adopt injury focused wearable technologies whilst running.
... Following the increase in female participation in distance running [12], investigations into gender differences in running mechanics were intensified in the Western world [12][13][14]. The gender difference studies indicated clear differences in females' body fat and running speed [3], resulting in distinct movement characteristics and injury etiology. ...
(1) Background: The aim of the present study was to examine the characteristics of over 70,000 long-distance finishers over the last four years in Chinese half- and full-marathon events; (2) Methods: The available data of all finishers (n = 73,485; women, n = 17,134; men, n = 56,351) who performed half- and full-marathon events in Hangzhou from 2016 to 2019 were further analyzed for the characteristics of gender, age and average running speed; (3) Results: The total men-to-women ratio was the lowest in the half-marathon event (1.86) and the highest in the full-marathon event (17.42). Faster running performance in males than in females and faster average running speed in short-distance runners were shown. Gender and race distance were observed to have the most significant effects on average running speed (p < 0.01). For both male and female finishers, the slowest running speed was shown in older age groups (p < 0.01) during the full marathon. Our results indicated that the gender difference in performance was attenuated in the longer race distances and older age groups; (4) Conclusions: Understanding the participation and performances across different running distances would provide insights into physiological and biomechanical characteristics for training protocols and sports gear development in different groups.
... 16 Following the retrospective study by Daoud et al., 14 there is an equal number of studies (both prospective and retrospective) which have weighed in whether MFS/FFS is protective or not. [17][18][19][20] Because of these findings, Anderson et al. 21 do not recommend in their systematic review with meta-analysis to modify their endurance runners' footstrike pattern to prevent running-related-injuries. ...
Purpose
To date, the relationship between footstrike pattern and performance, as well as with injury incidence in endurance running remains unclear. For these reasons, it is currently not recommended to modify footstrike pattern in an uninjured long-distance runner. The purpose of this study was to analyse whether athletic coaches apply these current scientific recommendations with their endurance runners on the field.
Methods
A Delphi method study was used to develop an online survey that was administered to French-speaking athletic coaches in Belgium. The survey comprised three sections: 1) coaches’ profile, 2) coaches’ perception of footstrike patterns, 3) practices pertaining to footstrike patterns.
Results
One hundred and fourteen respondents completed the entire questionnaire. Ninety-six (84%) athletic coaches reported modifying the footstrike pattern of their endurance runners. They reported that they modify their runners’ rearfoot and forefoot strike more often than a midfoot strike (P < 0.0001) to prevent injury (83%) and to improve performance (66%). According to them, midfoot strike is considered as the best landing pattern for endurance performance (47%) and injury prevention (36%) whereas rearfoot strike is considered as the worst (respectively, 50% and 52%).
Summary and conclusion
This study highlights the disparities between scientific recommendations and athletic coaches’ field practices for modifying footstrike patterns in endurance runners. Contrary to current scientific literature recommendations, a large proportion of coaches modify the natural footstrike pattern of their endurance runners towards a midfoot strike pattern to improve performance and prevent injury.
... However, while it may take less calf work to land with a RFS pattern, this evolutionary mismatch results in harder landings with greater vertical impact forces leading to greater rates of loading (Pohl et al., 2009;Zadpoor and Nikooyan, 2011;Bonacci et al., 2013). These increased impacts and rates of loading have been associated with common runningrelated injuries (Pohl et al., 2009;Zadpoor and Nikooyan, 2011;Davis et al., 2016;Futrell et al., 2018;Johnson et al., 2020;Johnson and Davis, 2021). ...
Recent studies have suggested that 95% of modern runners land with a rearfoot strike (RFS) pattern. However, we hypothesize that running with an RFS pattern is indicative of an evolutionary mismatch that can lead to musculoskeletal injury. This perspective is predicated on the notion that our ancestors evolved to run barefoot and primarily with a forefoot strike (FFS) pattern. We contend that structures of the foot and ankle are optimized for forefoot striking which likely led to this pattern in our barefoot state. We propose that the evolutionary mismatch today has been driven by modern footwear that has altered our footstrike pattern. In this paper, we review the differences in foot and ankle function during both a RFS and FFS running pattern. This is followed by a discussion of the interaction of footstrike and footwear on running mechanics. We present evidence supporting the benefits of forefoot striking with respect to common running injuries such as anterior compartment syndrome and patellofemoral pain syndrome. We review the importance of a gradual shift to FFS running to reduce transition-related injuries. In sum, we will make an evidence-based argument for the use of minimal footwear with a FFS pattern to optimize foot strength and function, minimize ground reaction force impacts and reduce injury risk.
... One randomized controlled study has shown that a gait retraining aiming to reduce vertical load rates has the potential to reduce occurrence of injuries [31]. While some studies have found associations between high load rates and certain injury pattern [32], no conclusive evidence is available today [3,33]. However, vertical load rates can be altered by cadence, footwear and gait retraining and therefore are of interest for the development of injury prevention strategies [34,35]. ...
The purpose of this chapter is to describe the interdisciplinary field of biomechanics and its importance in the evaluation of running. We will shortly describe the basic principles and origins of this scientific field and go into further details of new technical innovations. Then, a comprehensive overview of laboratory and field-based biomechanical analyses will be discussed in the light of implication for injury aetiology and prevention. Finally, we will end with a discussion on new research areas and implications for future research.
... Such injuries include plantar fasciitis, skeletal stress fractures, patellofemoral pain syndrome and iliotibial band syndrome. The forces that have shown the most consistent relationship with running-related repetitive stress injuries are impact transients (Davis et al., 2016;Johnson et al., 2020), the abrupt collision forces of approximately 1.5-3 times body weight that occur within the first 50 milliseconds after the foot strikes the ground. Thus, from the perspective of injury prevention, attenuation of impact transients is regarded as an important feature of good running technique (Lieberman, 2012(Lieberman, , 2021Lieberman et al., 2010). ...
Research among non-industrial societies suggests that body kinematics adopted during running vary between groups according to the cultural importance of running. Among groups in which running is common and an important part of cultural identity, runners tend to adopt what exercise scientists and coaches consider to be good technique for avoiding injury and maximizing performance. In contrast, among groups in which running is not particularly culturally important, people tend to adopt suboptimal technique. This paper begins by describing key elements of good running technique, including landing with a forefoot or midfoot strike pattern and leg oriented roughly vertically. Next, we review evidence from non-industrial societies that cultural attitudes about running associate with variation in running techniques. Then, we present new data from Tsimane forager-horticulturalists in Bolivia. Our findings suggest that running is neither a common activity among the Tsimane nor is it considered an important part of cultural identity. We also demonstrate that when Tsimane do run, they tend to use suboptimal technique, specifically landing with a rearfoot strike pattern and leg protracted ahead of the knee (called overstriding). Finally, we discuss processes by which culture might influence variation in running techniques among non-industrial societies, including self-optimization and social learning.
... Among those variables is the vertical instantaneous loading rate (VILR) of the ground reaction force (GRF). 2 The GRFs during running represent the total acceleration of the body's center of mass (BCOM) and are, according to Newton's second law, responsive to the accelerations of all body segments. 3,4 Therefore, it is not surprising that the maximal deceleration of the shank along the longitudinal axis upon footfall, also defined as the axial peak tibial acceleration (PTA a ), 5 correlates to the VILR (r range = 0.47 -0.76). ...
Purpose:
The present study aimed to determine if runners can reduce impact measures after a six-session in-the-field gait retraining program with real-time musical biofeedback on axial peak tibial acceleration (PTAa ) and identify the associated biomechanical adaptations.
Methods:
Twenty trained high-impact runners were assigned to either the biofeedback or the music-only condition. The biofeedback group received real-time feedback on the PTAa during the gait retraining program, whereas the music-only condition received a sham treatment. Three-dimensional gait analysis was conducted in the lab before (PRE) and within one week after completing the gait retraining program (POST). Subjects were instructed to replicate the running style from the last gait retraining session without receiving feedback while running overground at a constant speed of 2.9 m⸳s-1 .
Results:
Only the biofeedback group showed significant reductions in both PTAa (∆x̅ = -26.9%, p = 0.006) and vertical instantaneous loading rate (∆x̅ = -29.2%, p = 0.003) from PRE to POST. In terms of biomechanical adaptations, two strategies were identified. Two subjects transitioned towards a more forefoot strike. The remaining eight subjects used a pronounced rearfoot strike and posteriorly inclined shank at initial contact combined with less knee extension at toe-off while reducing vertical excursion of the center of mass.
Conclusions:
After completing a music-based biofeedback gait retraining program, runners can reduce impact while running overground in a lab. We identified two distinct self-selected strategies used by the participants to achieve reductions in impact.
... However, running also carries the risk of increased musculoskeletal injuries and there is a need to understand the etiology of injury in order to efficiently prevent it [1]. One of the important functions of the human musculoskeletal system is to attenuate and dissipate shock waves initiated with foot ground contact [2]. Those shock waves are initiated by most types of motion, such as walking and running. ...
The purpose of this study was to determine the effect of fatigue on impact shock wave attenuation and assess how human biomechanics relate to shock attenuation during running. In this paper, we propose a new methodology for the analysis of shock events occurring during the proposed experimental procedure. Our approach is based on the Shock Response Spectrum (SRS), which is a frequency-based function that is used to indicate the magnitude of vibration due to a shock or a transient event. Five high level CrossFit athletes who ran at least three times per week and who were free from musculoskeletal injury volunteered to take part in this study. Two Micromachined Microelectromechanical Systems (MEMS) accelerometers (RunScribe®, San Francisco, CA, USA) were used for this experiment. The two RunScribe pods were mounted on top of the foot in the shoelaces. All five athletes performed three maximum intensity runs: the 1st run was performed after a brief warmup with no prior exercise, then the 2nd and the 3rd run were performed in a fatigued state. Prior to the 2nd and the 3rd run, the athletes were asked to perform at maximum intensity for two minutes on an Assault AirBike to tire them. For all five athletes, there was a direct correlation between fatigue and an increase in the aggressiveness of the SRS. We noticed that for all five athletes for the 3rd run the average SRS peaks were significantly higher than for the 1st run and 2nd run (p < 0.01) at the same natural frequency of the athlete. This confirms our hypothesis that fatigue causes a decrease in the shock attenuation capacity of the musculoskeletal system thus potentially involving a higher risk of overuse injury.
... which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited. been reported in injured runners who had been medically diagnosed with injuries when compared to runners without any current or history of injuries (6,9). In addition, plantar pressure during running is a biomechanical measure that was suggested as a predictive parameter of sustaining an overuse injury (10). ...
Background: Running is a cyclic movement requiring bilateral symmetry between the lower limbs to reduce injury risk. The assessment of side-to-side differences is often performed to detect functional deficits.
Objectives: The purpose was to study side-to-side differences using clinical and running performance assessments in healthy runners (HR), runners with a history of lower limb injuries (RHI), and runners with a current lower limb injury (RLI).
Methods: Forty-three runners were recruited, with 14 participants being allocated to the HR group, 13 to the RHI group, and 16 to the RLI group. Peak vertical ground reaction force (GRF), midfoot pressure, foot rotation, and gait variability were recorded using a Zebris FDM-T treadmill analysis system. Participants were also assessed using the navicular drop test. Dependent t-tests were used to determine if any differences existed between the lower limbs within each group. One-way ANOVAs were then used to investigate the side-to-side differences between the three groups.
Results: Significant differences were seen in navicular drop height between lower limbs within both the HR (P = 0.02) and RHI (P = 0.009) groups, and side-to-side differences in foot rotation were greatest in the RLI group (~34%) compared to both the RHI (~30.5%) and HR (~24%) groups. The lateral variability of the center of pressure was greatest in the RLI group (37.1 mm) compared to the RHI (28.9 mm) and HR (22.2 mm) groups.
Conclusions: Variability of butterfly center of pressure diagram may help identify runners at a greater risk of lower limb injury. Side-to-side differences should be expected to progressively decrease from the injured stage, through the recovery and return to sport phases. Target goals of less than 34% side-to-side difference for foot rotation and 37.1 mm for the lateral center of pressure variability may be used to help the decision-making process when considering a return to running practice.
... As these factors have been associated with the development of specific running injuries such as e.g. stress fracture (Davis, Bowser, & Mullineaux, 2016;Milner, Ferber, Pollard, Hamill, & Davis, 2006) or plantar fasciitis (Pohl, Hamill, & Davis, 2009), different solutions of shoe cushioning have been proposed to attenuate landing impacts. ...
In a recent randomized trial investigating running shoe cushioning, injury risk was greater in recreational runners who trained in the shoe version with greater cushioning stiffness (Stiff) compared to those using the Soft version. However, vertical impact peak force (VIPF) was lower in the Stiff version. To investigate further the mechanisms involved in the protective effect of greater cushioning, the present study used an intra-subject design and analysed the differences in running kinematics and kinetics between the Stiff and Soft shoe versions on a subsample of 41 runners from the previous trial. Data were recorded in the two shoe conditions using an instrumented treadmill at 10 km.h⁻¹. VIPF was confirmed to be lower in the Stiff version compared to the Soft version (1.39 ± 0.25 vs. 1.50 ± 0.25 BW, respectively; p = 0.009, d = 0.42), but not difference was observed in vertical loading rate (p = 0.255 and 0.897 for vertical average and instantaneous loading rate, respectively). Ankle eversion maximal velocity was not different (p = 0.099), but the Stiff version induced greater ankle negative work (-0.55 ± 0.09 vs. -0.52 ± 0.10 J.kg⁻¹; p = 0.009, d = 0.32), maximal ankle negative power (-7.21 ± 1.90 vs. -6.96 ± 1.92 W.kg⁻¹; p = 0.037, d = 0.13) and maximal hip extension moment (1.25 ± 0.32 vs.1.18 ± 0.30 N.m.kg⁻¹; p = 0.009, d = 0.22). Our results suggest that the Stiff shoe version is related to increased mechanical burden for the musculoskeletal system, especially around the ankle joint.
Trial registration: ClinicalTrials.gov identifier: NCT03115437..
... The methods used are similar to those O n l i n e F i r s t previously described, although designs can be crosssectional, 27 retrospective, 28 or prospective. 29 Also, groups are usually matched on personal characteristics thought to be related to injury risk (eg, age, sex, body mass, training status, running experience), so that any differences in running biomechanics could theoretically be associated with the presence of injury. However, the direction of the relationship cannot be determined via case-control and retrospective studies, which strongly limits the scope of the conclusions that can be drawn. ...
... However, these conclusions are mostly based on case-control designs. A prospective study investigated impact forces as a potential injury risk factor in female runners, but no difference was observed between injured and uninjured runners (Davis et al., 2016). Secondary analyses showed that Fz1 and loading rates were greater in runners with a medically diagnosed injury compared to those who had never reported any previous injury. ...
Cushioning systems in running shoes are used assuming that ground impact forces relate to injury risk and that cushioning materials reduce these impact forces. In our recent trial, the more cushioned shoe version was associated with lower injury risk. However, vertical impact peak force was higher in participants with the Soft shoe version. The primary objective of this study was to investigate the effect of shoe cushioning on the time, magnitude and frequency characteristics of peak forces using frequency-domain analysis by comparing the two study groups from our recent trial (Hard and Soft shoe group, respectively). The secondary objective was to investigate if force characteristics are prospectively associated with the risk of running-related injury. This is a secondary analysis of a double-blinded randomized trial on shoe cushioning with a biomechanical running analysis at baseline and a 6-month follow-up on running exposure and injury. Participants ( n = 848) were tested on an instrumented treadmill at their preferred running speed in their randomly allocated shoe condition. The vertical ground reaction force signal for each stance phase was decomposed into the frequency domain using the discrete Fourier transform. Both components were recomposed into the time domain using the inverse Fourier transform. An analysis of variance was used to compare force characteristics between the two study groups. Cox regression analysis was used to investigate the association between force characteristics and injury risk. Participants using the Soft shoes displayed lower impact peak force ( p < 0.001, d = 0.23), longer time to peak force ( p < 0.001, d = 0.25), and lower average loading rate ( p < 0.001, d = 0.18) of the high frequency signal compared to those using the Hard shoes. Participants with low average and instantaneous loading rate of the high frequency signal had lower injury risk [Sub hazard rate ratio (SHR) = 0.49 and 0.55; 95% Confidence Interval (CI) = 0.25–0.97 and 0.30–0.99, respectively], and those with early occurrence of impact peak force (high frequency signal) had greater injury risk (SHR = 1.60; 95% CI = 1.05–2.53). Our findings may explain the protective effect of the Soft shoe version previously observed. The present study also demonstrates that frequency-domain analyses may provide clinically relevant impact force characteristics.
Clinical Trial Registration: https://clinicaltrials.gov/ , identifier: 9NCT03115437.
Outdoor running kinetic measurements like vertical ground reaction force (vGRF) need simple and accurate models. A previous study assessed a two mass model (2MM) on an athletic adult population during treadmill running, but not recreational adults during overground running. The objectives were to compare accuracy of the overground 2MM and an optimized version to the reference study and force platform (FP) measurements. Overground vGRF, ankle position, and running speed were collected on 20 healthy subjects in a laboratory. The subjects ran at three self-selected speeds and with an opposite foot strike strategy. Reconstructed 2MM vGRF curves were calculated with the original parameter values (Model1), with parameters optimized each strike (ModelOpt), and with group-based optimal parameters (Model2). Root mean square error (RMSE), optimized parameters, and ankle kinematics were compared to the reference study; peak force and loading rate were compared to FP measurements. The original 2MM showed decreased accuracy with overground running. ModelOpt overall RMSE was lower than Model1 (p > 0.001, d = 3.4). ModelOpt overall peak force was different but most like FP signals (p < 0.01, d = 0.7) and Model1 was most different (p < 0.001, d = 1.3). ModelOpt overall loading rate was similar to FP signals and Model1 was different (p < 0.001, d = 2.1). Optimized parameters were different (p < 0.001) from the reference study. 2MM accuracy was largely attributable to curve parameter choice. These may be dependent on extrinsic factors like running surface and protocol and intrinsic factors like age and athletic caliber. Rigorous validation is needed if the 2MM is to be used in the field.
Objectives:
To explore the immediate and retention effect of real-time tibial acceleration feedback on running biomechanics during gait retraining.
Methods:
Five electronic databases were searched to identify relevant studies published before May 2022. The included studies were evaluated for methodological quality and bias risk, and data were extracted. A meta-analysis was conducted on the primary outcomes, including peak tibial acceleration (PTA) and vertical ground reaction force. Subgroup analysis was performed by gender, feedback criterion, mode, dosage, fading, retention period, and running environment to evaluate the source of heterogeneity. Qualitative analysis was performed to describe other variables.
Results:
Fourteen studies (174 participants) were eligible. Meta-analysis showed that real-time tibial acceleration feedback reduced PTA (P < .01, P < .01), vertical impact peak (P = .004, P < .01), vertical average loading rate (P < .01, P < .01), and vertical instantaneous loading rate (P < .01, P < .01) after feedback and during retention period (5 min-12 mo). Subgroup analysis showed that the immediate effect of vertical impact peak was more noticeable with mixed gender (P = .005) and fading feedback (P = .005) conditions, and the retention effect of PTA was more noticeable with high feedback dosage (P < .01) and fading feedback (P < .01) conditions.
Conclusions:
Real-time tibial acceleration feedback can reduce PTA and vertical ground reaction force during gait retraining, and for periods of 5 minutes to 12 months when the feedback is removed.
Objectives The aim of this study was to measure the magnitude of forces in the joints of the lower limb whilst running barefoot and compare them to the forces generated whilst wearing running shoes with a thick midsole.Methods
Twenty-three volunteers who utilised running as their main sport or a training aid ran as training aid were included in this study. Each volunteer would run down a fourteen-meter-long corridor both barefoot and with running shoes. Forces for joints of the lower limb were collected using a Vicon motion analysis system and force plates. The joint forces for the ankles, knees and hips were taken as the largest joint force experienced during the stance phase and then averaged over five running trials.ResultsThere was significant reduction in the joint forces for the ankles, knees, and hips when barefoot running compared to the shod condition.Conclusion
Barefoot running could be utilised to prevent both acute and degenerative injuries of the lower limb.
Background:
High impact loads have been linked with running injuries. Fatigue has been proposed to increase impact loads, but this relationship has not been rigorously examined, including the associated role of muscle strength, power, and endurance.
Purpose:
To investigate the effect of fatigue on impact loading in runners, and the role of muscle function in mediating changes in impact loading with fatigue.
Methods:
Twenty-eight trained endurance runners performed a fixed-intensity time to exhaustion test at 85% of V̇O2max. Tibial accelerations were measured using leg-mounted inertial measurement units (IMUs) and sampled every minute until volitional exhaustion. Tests of lower-limb muscle strength, power, and endurance included maximal isometric strength (soleus, knee extensors, knee flexors), single leg hop for distance, and the one leg rise test. Changes in peak axial tibial acceleration (PTA, g) were compared between time-points throughout the run (0, 25, 50, 75 and 100%). Associations between the change in PTA and lower limb muscle function tests were assessed (Spearman's rho [rs]).
Results:
Peak tibial acceleration increased over the duration of the fatiguing run. Compared to baseline (0%) (9.1 g SD 1.6), there was a significant increase at 75% (9.9 g SD 1.7., p = 0.001) and 100% (10.1 g SD 1.8, p < 0.001), with no change at 25% (9.6 g SD 1.6, p = 0.142) or 50% (9.7 g SD 1.7, p = 0.053). Relationships between change in peak tibial acceleration and muscle function tests were weak and not statistically significant (rs = -0.153 to 0.142, all p > 0.05).
Conclusions:
Peak axial tibial acceleration increased throughout a fixed-intensity run to exhaustion. The change in PTA was not related to performance in lower limb muscle function tests.
Exoskeleton robots, which are wearable robots that assist human movement, have recently been developed to augment the performance of the human body. In this study, the ankle spring of lower-limb exoskeleton robots was created from a foam core sandwich-structured composite (FCSC) to support the running movement by storing and releasing elastic energy and to predict kinetic data using the self-sensed capacitance data from the structure. Through finite element analysis, the deformation behaviors of the FCSC ankle spring were analyzed and compared with those of a typical fiber-reinforced plastic composite ankle spring. Using a universal test machine, the capacitive-based self-sensing capability of the FCSC ankle spring was examined under several loading rates and cyclic loading. Furthermore, running tests with the lower-limb exoskeleton robot equipped with the FCSC ankle spring were performed on a treadmill. Horizontal and vertical ground reaction forces (GRFs) and capacitance values were obtained from the force plate embedded in the treadmill and FCSC ankle spring, respectively, at various running speeds. These data were used to train an artificial neural network (ANN) model as input and output data. Consequently, the trained ANN model predicted the kinetic data using the capacitance values of the FCSC ankle spring without additional sensors.
Background:
Plantar fasciitis (PF) is a common overuse injury experienced by runners. PF may decrease the ability of the plantar fascia to create tension and reduce stability of the foot. Stability of the foot is necessary for whole-body dynamic stability during running which consists of cyclical periods of single leg stance. Given that a major risk factor for running-related injury is previous injury, evaluating dynamic stability in runners with PF, runners with resolved PF, and healthy runners may elucidate differences between these individuals and clarify risk for secondary injury in these groups.
Research question:
Is dynamic stability reduced in runners with PF and runners with resolved PF compared to healthy runners?
Methods:
Thirty runners were recruited for this retrospective comparative study based on mileage and injury status: current PF (PF), resolved PF (RPF), or healthy (CON). Kinematic and kinetic data were collected during running and dynamic stability was determined by time-to-contact (TtC) analysis for early, mid, and late stance to the anterior, posterior, medial, and lateral boundary of the foot. Dynamic stability was compared between groups one-way ANOVAs (α = 0.05) and Tukey post-hoc tests conducted when appropriate. Cohen's d effect sizes (d) were reported for all TtC comparisons (small = 0.20, medium = 0.50, large = 0.80).
Results:
TtC values were shorter in PF compared to the other groups to all boundaries during mid-stance. TtC was significantly greater in PF compared to RPF to the anterior boundary during late stance.
Significance:
Shorter TtC observed in PF compared to the other groups during midstance may indicate reduced dynamic stability during the most stable portion of running which may lead to increased injury risk.
Background
While there is substantial information available regarding expected biomechanical adaptations associated with adult running-related injuries, less is known about adolescent gait profiles that may influence injury development.
Research Questions
Which biomechanical profiles are associated with prevalent musculoskeletal lower extremity injuries among adolescent runners, and how do these profiles compare across injury types and body regions?
Methods
We conducted a cross-sectional study of 149 injured adolescents (110 F; 39 M) seen at a hospital-affiliated injured runner’s clinic between the years 2016-2021. Biomechanical data were obtained from 2-dimensional video analyses and an instrumented treadmill system. Multivariate analyses of variance covarying for gender and body mass index were used to compare continuous biomechanical measures, and Chi-square analyses were used to compare categorical biomechanical variables across injury types and body regions. Spearman’s rho correlation analyses were conducted to assess the relationship of significant outcomes.
Results
Patients with bony injuries had significantly higher maximum vertical ground reaction forces (bony: 1.87 body weight [BW] vs. soft tissue: 1.79BW, p=0.05), and a higher proportion of runners with contralateral pelvic drop at midstance (χ²=5.3, p=0.02). Maximum vertical ground reaction forces and pelvic drop were significantly yet weakly correlated (ρ=0.20, p=0.01). Foot strike patterns differed across injured body regions, with a higher proportion of hip and knee injury patients presenting with forefoot strike patterns (χ²=22.0, p=0.01).
Significance
These biomechanical factors may represent risk factors for injuries sustained by young runners. Clinicians may consider assessing these gait adaptations when treating injured adolescent patients.
Background
Runners with a rearfoot strike pattern typically show high vertical ground reaction force loading rates (LRs), that are associated with injuries, compared with forefoot strikers. However, some runners with a rearfoot strike pattern run in a way that reduces LRs. Our purpose was to identify differences in running mechanics between rearfoot strike runners with high and low vertical LRs.
Methods
42 healthy runners, 21 with high (≥ 80.5 BW/s) and 21 with low (≤ 46.3 BW/s) LRs, were included in the current study. Lower extremity kinematic and kinetic data were then collected while participants ran along a 30 m runway. Running mechanics were calculated, including sagittal plane knee stiffness during early stance, the components of knee stiffness (Δ knee flexion and flexion moment), sagittal joint angles at initial contact, as well as cadence. The two LR groups were compared for differences in outcome variables using independent t-tests or Mann Whitney U tests.
Findings
Knee stiffness was significantly lower in the low LR group (p< 0.01, d= 0.87), due to higher knee flexion excursion (p< 0.01, d= 1.38). At initial contact, the low LR group showed lower hip and knee flexion, but greater ankle and foot dorsiflexion (p= 0.01-0.04, d= 0.64-0.93). No differences were found in cadence.
Interpretation
These results provide potential targets, related to gait kinematics and kinetics, for gait retraining aimed at reducing LRs in rearfoot strike runners.
The aim of this study was to assess acute effects of footwear conditions (barefoot, minimalist and standard running shoes) on running impact loading in the preschool years. Fourty-eight habitually shod preschool children (26 males and 22 females) were divided into four age groups (3-, 4-, 5- and 6-year-old). Children performed a simple running game in three different conditions. Three-dimensional biomechanical analysis was carried out during overground running. Statistical parametric mapping was performed on the vertical ground reaction force profiles during the stance phase and one-way repeated measures ANOVA on the vertical instantaneous loading rate. Three-year-old children displayed significantly lower vertical ground reaction force values in the barefoot condition compared to minimalist (3-7% stance) and standard running shoes (7-11% stance). There were also differences in vertical instantaneous loading rate, where 3-year-olds had lower loading when barefoot than in minimalist (p = 0.010, d = 1.19) or running shoes (p = 0.045, d = 0.98), despite no differences in the footstrike pattern (mostly rearfoot-midfoot strike). No differences were found for the older children. Running in minimalist shoes did not imitate barefoot running in 3-year-old children. On the contrary, increased loading was observed in minimalist shoes in early running developmental stages.
Introduction:
Loading rate (LR), the slope of the vertical ground reaction force (vGRF), is commonly used to assess running-related injury risk. However, the relationship between LR and running-related injuries, including bone stress injuries (BSI), is unclear. Inconsistent findings may result from the numerous LR calculation methods that exist and their application across different running speeds.
Purpose:
Assess the influence of calculation method and running speed on LR values and determine the association of LR during healthy running with subsequent injury.
Methods:
Healthy preseason running data and subsequent injury records from Division I cross country athletes (n = 79) over four seasons (2015-2019) at 2.68 m/s, preferred training pace, and 4.47 m/s were collected. LR at each speed was calculated four ways: 1) maximum and 2) average slope from 20-80% of vGRF magnitude at impact peak (IP), 3) average slope from initial contact to IP, and 4) average slope from 3-12% of stance time. Linear mixed effects models and generalized estimation equations were used to assess LR associations.
Results:
LR values differed depending on speed and calculation method (p-value <0.001). The maximum slope from 20-80% of the vGRF at 4.47 m/s produced the highest LR estimate and the average slope from initial contact to IP at 2.68 m/s produced the lowest. Sixty-four injuries (20 BSI) were observed. No significant association was found between LR and all injuries or BSI across any calculation method (p-values ≥0.13).
Conclusions:
Calculation method and running speed result in significantly different LR values. Regardless of calculation method, no association between LR and subsequent injury was identified. Thus, healthy baseline LR may not be useful to prospectively assess running-related injury risk.
Purpose
: Bone stress injuries (BSIs) are common in female runners, and recurrent BSI rates are high. Previous work suggests an association between higher impact loading during running and tibial BSI. However, it is unknown whether impact loading and fatigue related loading changes discriminate women with a history of multiple BSIs. This study compared impact variables at the beginning of a treadmill run to exertion and the changes in those variables with exertion among female runners with no history of BSI as well as among those with a history of 1 or multiple BSIs.
Methods
: We enrolled 45 female runners (aged 18–40 years) for this cross-sectional study: having no history of diagnosed lower extremity BSI (N-BSI, n = 14), a history of 1 lower extremity BSI (1-BSI, n = 16), diagnosed by imaging, or a history of multiple (≥3) lower extremity BSIs (M-BSI, n = 15). Participants completed a 5 km race speed run on an instrumented treadmill while wearing an Inertial Measurement Unit (IMU). Vertical average loading rate (VALR), vertical instantaneous loading rate (VILR), vertical stiffness during impact via instrumented treadmill, and tibial shock determined as the peak positive tibial acceleration via IMU were measured at the beginning and end of the run.
Results
: There were no differences between groups in VALR, VILR, vertical stiffness, or tibial shock in a fresh or exerted condition. However, compared to N-BSI, women with M-BSI had greater increase with exertion in VALR (–1.8% vs. 6.1%, p = 0.01 and VILR (1.5% vs. 4.8%, p = 0.03). Similarly, compared to N-BSI, vertical stiffness increased more with exertion among women with M-BSI (–0.9% vs. 7.3%, p = 0.006) and 1-BSI (–0.9% vs. 1.8%, p = 0.05). Finally, compared to N-BSI, the increase in tibial shock from fresh to exerted condition was greater among women with M-BSI (0.9% vs. 5.5%, p = 0.03) and 1-BSI (0.9% vs. 11.2%, p = 0.02).
Conclusion
: Women with 1-BSI or M-BSIs experience greater exertion-related increases in impact loading than women with N-BSI. These observations imply that exertion-related changes in gait biomechanics may contribute to risk of BSI.
Running after childbirth, specifically how or when to return, is a hot topic in the field of physical therapy and on social media; however, there are significant gaps in the literature supporting when and how to safely initiate running postpartum. During pregnancy and following childbirth (both vaginal and cesarean), the body undergoes changes that may impact strength, neuromuscular control, endurance, and the ability to withstand the high-impact forces and repetitive nature of running. Many mothers experience new or worsened symptoms of musculoskeletal or pelvic floor dysfunction following pregnancy and childbirth and require physical therapy to normalize function. After most major injuries, it is common to participate in formalized rehabilitation; however, this is not the norm for athletes returning to running postchildbirth. Because of lack of evidence, many runners and clinicians struggle to develop appropriate rehabilitation progressions for return to running after childbirth. Pelvic and sports physical therapists must understand biomechanical features of running gait and safely progress strength, endurance, and neuromuscular control of the kinetic chain when guiding a runner back to running. This clinical commentary builds on existing guidelines, research, and expert opinion to propose a 4-phase rehabilitation framework to help runners initiate and progress running after childbirth. The result is an in-depth exercise prescription (intensity, frequency, type), examples of exercises (hip, abdominal, pelvic floor, and foot), running progression, and progression goals to prepare runners for symptom-free running after childbirth (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JWHPT/A58, where authors provide more insight on this return to running framework).
Introduction:
Many gait retraining studies use cues that promote internal focus of attention. However, the motor control literature clearly shows the beneficial effects of using cues that promote an external focus of attention (EFOA) when teaching new movements. This case report seeks to illustrate the outcomes of using an EFOA for running gait retraining. It also examines whether retrained mechanics transfer across different running speeds.
Case descriptions:
A 22-year-old female competitive runner with a history of tibial stress injuries was the participant.
Patient management:
Baseline assessments of flexibility, strength, and running biomechanics were performed after which an eight-session gait retraining protocol was implemented. Visual (mirror) and verbal feedback (EFOA) cues were provided during the retraining protocol. Outcomes showed improved hip, knee, and ankle kinematics, reduced ground reaction forces, and earlier onset and longer durations of muscle activity following retraining. These improvements transferred across running speeds.
Discussion and conclusion:
In this participant, EFOA cues were effective for the gait retraining protocol and the benefits were transferable across running speeds. Clinicians should consider how EFOA cues may be incorporated to improve gait retraining outcomes.
Running is a gross-motor skill and a popular physical activity, though it comes with a risk of injury. Gait retraining is performed with the intent on managing the risk of running injury. The peak tibial acceleration may be linked with running injuries and is suitable as input for biofeedback. So far, retraining programs with the use of biofeedback on peak tibial acceleration have been bound to a treadmill. Therefore, the objective of this doctoral thesis was to evaluate the effectiveness of a novel music-based biofeedback system on peak tibial acceleration in the context of gait retraining in a training environment. This system is wearable and has lightweight sensors to attach to the lower leg. The sensor first records the tibial acceleration. Then, a processing unit detects the acceleration spike for direct auditory biofeedback.
Studies 1 to 5 covered the measurement of peak tibial accelerations, the design of the music-based feedback, and the effectiveness evaluation of the biofeedback system for impact reduction in a training center. In study 1 the peak tibial acceleration of a group of distance runners was reliable in the same test and repeatable in a re-test. The peak tibial accelerations increased with running speed and were correlated with the maximum vertical loading rate of the ground reaction force, which is an impact characteristic derived in the biomechanics laboratory. The developed peak detection algorithm identified the peak tibial acceleration in real-time. The music-based feedback was developed in study 2. The music was superimposed with perceptible pink noise. The noise intensity could be linked to a biological parameter such as the peak acceleration tibial. The tempo of the music synchronized with the cadence of the runner to motivate the runner and allowed for a user-induced change in cadence in response to the biofeedback. Studies 3 to 5 examined the effectiveness of music-based biofeedback on the peak tibial peak in a training environment. We demonstrated that smaller peak values are achievable with the aid of the validated biofeedback system. In study 3, ten runners with high peak tibial acceleration were subjected to biofeedback on the momentary peak tibial acceleration. The group was able to reduce their peak tibial acceleration by 27% or 3 g in the biofeedback condition. Study 4 evaluated the initial learning effect within a single session at ~11.5 km/h. The main change in peak acceleration occurred after approximately 8 minutes of biofeedback. However, there was substantial between-subject variation in time which ranged from 4 to 1329 gait cycles. Study 5 confirmed the effectiveness of the biofeedback in a quasi-randomized study with control group. The experimental group received the biofeedback in a 3-week retraining program comprising of biofeedback faded in time. The control group received tempo-synchronized music as placebo. A running speed of approximately 10 km/h was maintained session after session via speed feedback. All runners completed the running program consisting of 6 sessions. The peak acceleration decreased by 26% or 3 g in the experimental group. The smaller peak values in studies 3-5 must have resulted from a movement alteration, although there was no significant change in running cadence at the group level.
Studies 6 to 9 give insight into possible strategies for low(er) peak tibial acceleration in level running. In study 6, we discovered that peak tibial accelerations depend on the manner of heel striking. Specifically, a more pronounced heel landing was correlated with smaller axial (1D) and resultant (3D) peak tibial accelerations. The multicenter results of study 7 showed greater resultant peak acceleration in non-rearfoot strikes compared with heel strikes. This greater acceleration was due to an abrupt horizontal deceleration of the lower leg. In study 8, we described and compared the running mechanics of a successful long-distance runner with low (impact) load and a high load capacity. A pronounced heel strike in conjunction with long stance and short flight phases characterized a low-impact runner who successfully completed 100 marathons in 100 days. Study 9 documented adaptations post-biofeedback in a lab center. There was no clear relationship between the changes in peak tibial acceleration and in running cadence, which confirmed the results of the data captured in the training center. Casuistry showed visually detectable changes in the curve of the vertical ground reaction force. A runner with high peak tibial acceleration peaks changed to a more pronounced rearfoot strike or changed to a non-rearfoot strike pattern to reduce the axial peak tibial acceleration. These results suggest the existence of different distal strategies for impact reduction elicited by biofeedback.
Our experiments opened the possibility of impact reduction with the use real-time auditory biofeedback that is perceptible and motivating. Two motor strategies were discovered to run with less peak tibial acceleration. We hope these findings offer encouragement for runners, coaches and clinicians who wish to target a form of low(er) impact running. The biofeedback system effectively modified the running form and has great ecological value due to the portable hardware and energy source for outdoor usage. User-oriented biofeedback systems should become available for the consumer and the patient if proven useful for respectively injury reduction and injury management. Overall, this doctoral thesis contributed to a better understanding of impact severity in distance running and its reduction in a gait retraining context with the use of real-time music-based biofeedback.
Objectives
Hip/groin running-related injuries (RRI) are relatively uncommon. It is unclear if runners of either sex are disproportionately affected. Our objective was to systematically review differences in hip/groin RRIs between males and females.
Data Sources
A structured and comprehensive search of four medical literature databases was performed (PubMed, Embase, Ovid Medline, and CINAHL). Terms searched were: risk, epidemiology, hip injury, groin injury, overuse injury, running, sprinting, and track and field.
Study Selection
Studies reporting sex-specific data on hip/groin RRIs in adult runners were included. Data was extracted and reviewed independently by two authors.
Study Appraisal and Data Synthesis
Sex-specific injury rates, risk factors, and return to sport (RTS) following hip/groin RRI were extracted. Risk of bias was assessed using the Joanna-Briggs Institute Critical Appraisal Tool.
Results
10 studies with 7,353 total runners were included: 2,315 (47%) males and 2,559 (53%) females. The mean age of included runners was 37.3 ± 8.9 years and mean weekly running distance was 10.4 ± 8.4 km. Hip/groin injuries comprised 10.1% (491/4,874) of total RRIs, including 6.3% of RRIs sustained by males and 11.0% by females. Three studies reported significantly higher rates of hip/groin RRIs in female runners. One study reported significantly higher rates of gluteus medius and adductor RRIs for females and males, respectively. One study identified female sex as an independent risk factor for hip/groin RRIs. Three studies reported on RTS after hip/groin RRIs: the pooled RTS rate was 81.4% (57/70) at 1 to 368 days after injury.
Limitations
Data was pooled when possible; however, there was considerable clinical, methodological, and statistical heterogeneity across studies.
Conclusions
Hip/groin RRIs comprise a greater percentage of total injuries among injured female runners relative to males. Females may be at a higher risk for sustaining hip/groin RRIs, though more research on risk factors and RTS is needed.
Decreased daily activities and tension frequently cause excessive muscle co-contractions implicitly, resulting in decreased performance and injury in sports. In this study, we modify the interaction between the environment and human body freely and temporarily, using environmental kinodynamic intervention. We target the load reduction during walking, which is realized by walking on a treadmill, where the acceleration/deceleration of the treadmill acts as the intervention. A forward dynamics simulation using a kinodynamic body model is used to design the intervention pattern. The designed intervention pattern is implemented in a real environment for verification, using a subject experiment with six subjects. The results demonstrate that the vertical component of the ground reaction force decreases by 2.14% and gastrocnemius and tibialis anterior activities decrease by 1.89% and 7.08E−01% when the treadmill speed is low at heel contact and accelerates gradually. Hence, we conclude that the intervention decreases the change in the muscle length during walking, suppresses the stretch reflex, and reduces muscle activity. These results demonstrate the possibility to modify human motor control systems using non-invasive kinodynamic interventions, thereby realizing implicit muscle relief (DATSURYOKU) in sports and daily life, as well as to prevent their injuries.
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