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The effect of the heel-to-toe drop of standard running shoes on lower limb biomechanics
Abstract
Running brings many health benefits, but can lead to injuries to the musculoskeletal system. Modern running shoes have been developed to improve running biomechanics, including the heel-to-toe-drop (HTD) which has been highlighted as a central feature in shoe design. The purpose of this study was to investigate impact force characteristics, joint kinematics and kinetics across three commonly-available HTDs, as well as between running with HTDs and barefoot. Fifteen recreational runners took part in this study. Full-body kinematics and ground reaction force (GRF) data were collected while the participants ran at a speed of 4 m/s in three different shoe conditions (4 mm, 8 mm, and 12 mm HTD) as well as barefoot. Comparisons between the four conditions were made for GRFs, joint kinematics and kinetics of the lower extremities. The results primarily showed that a 4 mm HTD led to increased vertical loading rate and maximum ankle moment and a decreased maximum knee moment compared to 8 mm and 12 mm HTD. In addition, differences in ankle and knee kinematics were seen between running in shoes and running barefoot. A lower HTD mainly altered the kinetics of the ankle and knee. Running with a low HTD did not lead to similar lower limb biomechanics as barefoot running. These findings are important because a deeper understanding of biomechanical responses may lead to more customized footwear, which could decrease the risk of running-related injuries.
... Caution should be used when interpreting F I G U R E 1 1 Knee flexion moment (y axis) graphed against run speed (x axis). Data were included from studies where data were normalized via Nm/kg and methodological quality scores were "moderate" or higher 23,49,50,54,55,62,70,79,80,90,95,99,100,102,107,109,111,115,117,118,138,139 The regression presented is only applicable for run velocities between 4 and 10 m/s. An exponential curve fitted to the data reports an R 2 value of 0.81, meaning 81% of the variance in knee flexion moment is explained by run speed. ...
... Data were included from studies where data were normalized via Nm/kg and methodological quality scores were "moderate" or higher. 23,49,50,54,62,80,90,95,99,102,107,109,111,115,117,118,138 The regression presented is only applicable for run velocities between 4 and 10 m/s. An exponential curve fitted to the data reports an R 2 value of 0.68, meaning 68% of the variance in hip extension moment is explained by run speed. ...
... m/s). Random effects model, N = 8, heterogeneity: I 2 = 95.43.50,54,62,102,109,111,118 A prediction interval is an estimated range of values that are statistically predicted to contain the value of a single new observation. ...
Introduction: Hamstring strain injury (HSI) remains a performance, economic, and player availability burden in sport. High-speed
running (HSR) is cited as a common mechanism for HSI. While evidence exists regarding the high physical demands on the hamstring muscles in HSR, meta-analytical synthesis of related
activation and kinetic variables is lacking.
Methods: A systematic search of Medline, Embase, Scopus, CINAHL, SportDiscus, and Cochrane library databases was conducted in accordance with the PRISMA 2020 guidelines. Studies reporting hamstring activation (electromyographic [EMG]) or hamstring muscle/related joint kinetics were included where healthy adult participants ran at or beyond 60% of maximum speed (activation studies) or 4 m per second (m/s (kinetic studies).
Results: A total of 96 studies met the inclusion criteria. Run intensities were categorized as “slow,” “moderate,” or “fast” in both activation and kinetic based studies with appropriate relative, and raw measures, respectively. Meta-analysis revealed pooled mean lateral hamstring muscle activation levels of 108.1% (95% CI: 84.4%–131.7%) of maximal voluntary isometric contraction (MVIC) during “fast” running. Meta-analysis found swing phase peak knee flexion internal moment and power at 2.2 Newton meters/kilogram (Nm/kg) (95% CI: 1.9–2.5) and
40.3 Watts/kilogram (W/kg) (95% CI: 31.4–49.2), respectively. Hip extension peak moment and power was estimated as 4.8 Nm/kg (95% CI: 3.9–5.7) and 33.1 W/kg (95% CI: 17.4–48.9),
respectively.
Conclusions: As run intensity/speed increases, so do the activation and kinetic demands on the hamstrings. The presented data will enable clinicians to incorporate more objective measures into the design of injury prevention and return-to- play
decision-making strategies.
... It should note that four studies do not indicate the volume of training practiced by the subjects before the study (Besson et al., 2019;Chambon et al., 2015;Malisoux et al., 2017;Yu et al., 2021). ; In ten studies, a sample of between 10 and 20 subjects was used (Besson et al., 2019;Chambon et al., 2015;Fu et al., 2022;Horvais & Samozino, 2013;Mo et al., 2020;Moody et al., 2018;Richert et al., 2019;Yu et al., 2021;Zhang et al., , 2022, while the other two studies used samples of 38 and 59 subjects, respectively. (Gij on-Noguer on et al., 2019; Malisoux et al., 2017). ...
... (Gij on-Noguer on et al., 2019; Malisoux et al., 2017). In six studies, only were studied men (Chambon et al., 2015;Horvais & Samozino, 2013;Mo et al., 2020;Richert et al., 2019;Yu et al., 2021;Zhang et al., 2022); in three studies, only women were studied (Besson et al., 2019;Fu et al., 2022; Gij on-Noguer on et al., 2019), in two, a mixed sample was studied (Malisoux et al., 2017;Moody et al., 2018). One study did not specify the sex of the participant . ...
... In five of the studies, the measurements were performed on treadmill (Gij on-Noguer on et al., 2019; Horvais & Samozino, 2013;Malisoux et al., 2017;Mo et al., 2020;Moody et al., 2018), while six were carried out exclusively over ground (Besson et al., 2019;Fu et al., 2022;Richert et al., 2019;Yu et al., 2021;Zhang et al., , 2022. A study analysed the running performed on treadmill and over ground (Chambon et al., 2015). ...
Heel-to-toe drop (HTD) values may modify the running biomechanics. However, more than twenty additional footwear characteristics may contribute to this too. The aim of this review was to identify and systematise the specific effects caused by different HTDs on running bio-mechanics. A systematic search was carried out in seven online databases and Footwear Science according to PRISMA protocol for studies that included the practice of endurance running in running shoes with different HTD types. A modified Downs and Black checklist was used to assess the risk of bias. Characteristics of the studies and footwear, the equipment used, and bio-mechanical outcomes were extracted for qualitative synthesis. Twelve studies were included. Only one had a randomised control trial design, which was classified as 'good' (score ¼ 24) quality. The studies reported thirty-nine kinematic and sixteen kinetic variables. HTD ranged between À8 to 16 mm. HTDs did not produce modifications in contact and flight time, stride frequency, and stride length. Some controversial evidence supports that the foot strike pattern changes towards forefoot strike only with HTD 0 compared to HTD 8-10. All evidence indicates that HTD values modified neither ankle, knee, or hip kinematics. Greater evidence supports that the modification of HTD in running shoes does not modify the values of GRF. Despite the controversial nature of the data, the trend is that a lower HTD shows a higher vertical loading rate. The different HTDs modified neither of the joint moments. The negative HTD could be an interesting variable to consider for future research. In addition, it is necessary to study the relationship between the HTD values and different combinations of heel height and forefoot height.
... Alterations such as heel-to-toe drop modifications, which is the difference in height of the heel and the forefoot, have been shown to affect vertical loading rates or the time over which the GRF is applied. Richert et al. reported greater vertical loading rates and impact peak durations in shoes with 8 mm and 4 mm heel-to-toe drops, which differ from the typical 10-12 mm heel-to-toe drop [9]. When comparing midsole thickness, Hannigan et al. reported a significant decrease in vertical loading rates when comparing maximal cushioning to minimal cushioning [10]. ...
... Some examples of alterations that influenced GRFs were varying heel-to-toe drops and midsole thickness. Richert et al. reported a greater vertical loading rate in a 4 mm heel-to-toe drop when compared to 8 mm, 12 mm, and barefoot running [9]. Similarly, when comparing the effect of midsole thickness on GRF variables, it was found that a minimal amount of cushioning produced greater vertical loading rates when compared to maximal cushioning and traditional cushioning [10]. ...
... Additionally, when comparing 15 mm, 10 mm, 5 mm and 0 mm drops, Zhang et al. found that patellofemoral joint force was significantly higher in shoes with 15 mm and 10 mm drops when compared to shoes with a 0 mm drop [12]. GRF variables were used in these studies to determine the potential lessening of impactrelated forces on lower limb joints when comparing shoe conditions, all of which showed alterations that were then related to the potential of having a decreasing effect on injury in the patellofemoral joint and ankle joint regions as these are areas where injuries most frequently occur in runners [5,6,9,10,12]. When considering female runners, Sinclair et al. reported significantly greater patellofemoral knee loading rates when compared to males, as such women may benefit from a gender specific shoe that contains adaptations to try and reduce these forces [19]. ...
Alterations in running shoe design have been studied and used in the prevention of injury and enhancement of performance allowing running shoe companies to market to a variety of runners based on skill level, foot-strike pattern, and even sex. These alterations have been shown to affect biomechanical and physiological variables associated with running. Some shoe companies have designed shoes specifically for biological female runners due to the morphological differences found between male and female feet. The purpose of this study is to determine if sex-specific running shoes can alter female runner biomechanics or physiology. Female runners were asked to run in the male and female models of the Altra Torin 4 Plush shoe to determine if there were differences in ground reaction forces (GRFs), sagittal plane joint angles and moments, oxygen consumption (VO2), respiratory exchange ratio (RER), and perceived level of comfort while running; There were no significant differences in GRFs, sagittal joint angles and moments, VO2, RER, or perceived comfort; There were no differences in measured biomechanical or physiological variables between the female and male version of the shoes suggesting that the alterations made to the female-specific shoe do not provide any additional benefit to female recreational runners.
... However, a lower HTD was found to result in a greater impact peak and vertical loading rates of the ground reaction force during treadmill running (Besson, Morio, Millet, & Rossi, 2019;Chambon et al., 2015). Similarly, Richert, Stein, Ringhof, and Stetter (2019) indicated a greater vertical loading rate in 4-mm HTD when compared with 12-mm HTD. ...
... In addition to the footstrike angle, impact peak and vertical loading rates of the ground reaction force, HTD has also been extensively examined in relation to spatiotemporal characteristics. No significant differences were reported in ground contact time among different HTDs (Besson et al., 2019;Chambon et al., 2015;Moody, Hunter, Ridge, & Myrer, 2018;Richert et al., 2019), whereas Horvais and Samozino (2013) reported a positive correlation between HTD and ground contact time. Cadence and/or step length were found to be no differences among different HTDs (Horvais & Samozino, 2013;Richert et al., 2019). ...
... No significant differences were reported in ground contact time among different HTDs (Besson et al., 2019;Chambon et al., 2015;Moody, Hunter, Ridge, & Myrer, 2018;Richert et al., 2019), whereas Horvais and Samozino (2013) reported a positive correlation between HTD and ground contact time. Cadence and/or step length were found to be no differences among different HTDs (Horvais & Samozino, 2013;Richert et al., 2019). ...
Effects of heel-toe drop remain largely unknown during running in cushioned shoes, which usually present a standard heel stack height (e.g. 21 mm). The purpose of this study was to investigate the isolated effect of heel-toe drop on running kinematics and kinetics and perceived footwear comfort of runners in standard cushioned shoes. Fifteen male habitual rearfoot strike runners ran in four shod conditions: no drop (0 mm, D0), 4-mm (D4), 8-mm (D8), and 12-mm drop (D12). Running kinematics and kinetics were collected using motion capturing system and instrumented treadmill, respectively. Footwear comfort was acquired immediately after each running trial using a visual analogue scale. Significant effects were demonstrated on footstrike angle (p < 0.001), stride length (p ¼ 0.005), and cadence (p ¼ 0.015). A greater footstrike angle was indicated during running in D8 compared with D4 (p ¼ 0.034) and D0 (p ¼ 0.006). However, such reduction was not sufficient to cause footstrike pattern transition towards a midfoot/forefoot strike pattern. Stride length in D8 was significantly larger than in D12 (p ¼ 0.007). No significances were found on vertical loading rates, contact time and perceived footwear comfort (p > 0.05). The isolated effects of heel-toe drop on running biomechanics were demonstrated in shoe models with a standard heel stack height. A lower heel-toe drop of standard cushioned shoes may reduce footstrike angle and increase stride length during running.
... Considering that it is plausible to induce running injuries in occasional runners when running in shoes with higher heel lift or heel-toe drop [14,[29][30][31][32][33], it is believed to lower loading rate and thereby reduce the risk of running-related injuries [28,34,35]. Moreover, arch-support orthoses may provide support on the midfoot structure and thereby affect forefoot mechanics during push-off [36], but this was not investigated in previous biomechanical studies on the effectiveness of arch-support orthoses. ...
... In our study, wearing higher heel lift (e.g., D10) orthoses was shown to be associated with smaller loading rate, but larger rearfoot touchdown angle when compared to wearing lower heel lift orthoses (e.g., D2 and control). This is in line with previous studies, which suggested that wearing shoes with higher heel lift would lead to a smaller loading rate and larger foot strike angle [14,25,29,32,47,50]. The decrease in loading rate would be resulted from lower peak pressure and contact area at rearfoot region in higher heel lift condition [51]. ...
While foot orthosis is suggested to improve rearfoot motion in running, little information is known about forefoot biomechanics. The objective of this study was to examine the effects of arch-support orthoses with various heel lift manipulation on the loading rate, spatiotemporal, and forefoot joint mechanics using a skin marker set model. Fifteen male habitual rearfoot strikers ran at their selected speeds on an instrumented treadmill in four foot orthoses conditions: flat-control, D2 (2 mm heel lift, arch-support), D6 (6 mm heel lift, arch-support), and D10 (10 mm heel lift, arch-support). A repeated measures ANOVA was performed to examine any significant difference in each of the tested variables, with α = 0.05. Wearing D10 led to smaller maximum loading rate than D2 (p < 0.001) and control (p = 0.002). For sagittal plane, D10 had larger rearfoot touchdown dorsiflexion than D2 (p = 0.027) and control (p = 0.007) and larger in D6 than control (p = 0.025). For frontal plane, wearing D10 demonstrated larger rearfoot frontal RoM than D2 (p = 0.018) and peak forefoot eversion than D6 (p = 0.047) and control (p = 0.048). Furthermore, the forefoot frontal range of motion was lowest when wearing D6. For joint moment, wearing control orthosis exhibited larger peak rearfoot eversion moment than D6 (p = 0.035), but smaller peak knee extension moment than D2 (p = 0.025) and D10 (p = 0.010). These findings indicate that the use of arch-support orthoses would alter the running mechanics that are related to injury potential. Lower heel lift orthoses led to alternations to most of the biomechanical variables than higher heel lift orthoses. Further longitudinal study seems necessary to optimize arch-support orthoses design in running.
... This study has found another piece of puzzle in understanding the effects of stack heights on running style and stability. Future studies may focus on running coordination (Garofolini et al., 2024) as well as analysis of joint loads (Richert et al., 2019) and muscle activities (Santuz et al. 2020) to better understand stack height effects. ...
The footwear market contains a wide variety of running shoe solutions aiming at optimizing performance and minimizing injuries. Stack height is one of the most highly discussed design features of running shoes, but its effects are not yet well understood. This study investigated the effects of different shoes differing mainly in their stack heights (High: 50 mm, Medium: 35 mm & Low: 27 mm) on running style and stability during treadmill running at 10 and 15 km/h. A total of 17 healthy experienced runners participated in this study. The kinematic data were recorded with a 3D motion capturing system. The running style was investigated by a dual-axis framework with duty factor (DF) and leg length normalized to step frequency (SFnorm). Additionally, the ratio of landing to take-off duration, the lower body joint angle time series in the sagittal and frontal planes, the vertical center of mass oscillation (COMosc), and the stiffness parameters (kver & kleg) were compared for different conditions. The stability was analyzed using linear (i.e. discrete frontal ankle parameters) and nonlinear methods (i.e. Maximum Lyapunov Exponent for local dynamic stability of head, trunk, hip, and foot, and detrended fluctuation analysis of stride time). High resulted in longer ground contact relative to stride time (DF) compared to Low. The higher the stack height, the higher was the COMosc. Furthermore, High led to a longer foot eversion during stance compared to Medium. In addition, the local dynamic stability of the hip decreased with High in comparison with Low. The higher stack heights (≥ 35 mm) led to a lower SFnorm at 15 km/h but not at 10 km/h. The remaining shoe effects were independent of the running speed. Findings showed that changes in stack height can affect running style. Furthermore, the highest stack height resulted in changes related with instabilities (i.e., longer foot eversion and lower hip dynamic stability) which may be a critical issue in terms of injuries and performance. However, this study did not include joint load analysis or running performance measures such as VO2. Future studies may benefit from the combination of analysis approaches to better understand stack height effects on running injuries and performance.
... Biomechanical variables were normally distributed except for the initial peak twisting moment and ankle external rotation moment. Regarding biomechanical variables, one-way repeated measures ANOVA test was conducted for normally distributed datasets to compare three shoe conditions as a repeated measure (within-subject factors) for each dependent variable [67]. Friedman test was used for the datasets with non-normal distribution. ...
Directional changes in cutting maneuvers are critical in sports, where shoe torsional stiffness (STS) is an important factor. Shoes are designed based on different constructions and movement patterns. Hence, it is unclear how adjustable spacers into the sole constructions of air pressure chambers (APC) affect the STS in side-step cutting. Therefore, this study investigated the effects of altered STS through adjustable sole spacers on ground reaction force (GRF) and ankle and knee joint moments in side-step cutting. Seventeen healthy recreational athletes performed side-step cutting with experimental conditions including (i) barefoot (BF), (ii) unaltered shoes (UAS): soles consisting of APC, and (iii) altered shoes (AS): modified UAS by inserting elastomeric spacers into cavities formed by APC. Mechanical and biomechanical variables were measured. Significant differences were revealed across shoe conditions for impact peak (p = 0.009) and impulse (p = 0.018) in vertical GRF, time to achieve peak braking (p = 0.004), and peak propulsion (p = 0.025) for anterior-posterior GRF in ANOVA test. No significant differences were observed in GRF peaks and impulses between UAS and AS except for a trend of differences in impact peak (p = 0.087) for vertical GRF. At the ankle and knee joint, peak ankle power absorption (p = 0.019), peak knee internal rotation moment (p = 0.042), peak knee extension moment (p = 0.001), peak knee flexion moment (0.000), peak knee power absorption (p = 0.047) showed significant difference across three shoe conditions. However, no significant differences between the UAS and AS were noticed for peak joint moments and power. Altered shoe torsional stiffness did not significantly affect the peak forces and peak ankle and knee joint moments or powers; hence sole adjustment did not influence the cutting performance. This study might be insightful in sports footwear design, and adjusting shoe torsional stiffness by sole modification might be advantageous for athletes playing sports with cutting maneuvers to reduce the risk of injuries by controlling the twisting force at the ankle that frequently happens during cutting maneuvers.
... Concerning the general effects of midsole geometries on BRFs without considering covariates, most of the included studies have addressed the effect of midsole geometry on GRF parameters. An increase in heel-toe drop has been reported to reduce vertical GRF loading rates [70][71][72][73]. Diverse results have been reported for midsole thickness, for which one study found lower vertical GRF loading rates in thicker than thinner midsoles [74], whereas another study could not identify any differences [75]. ...
Injury prevention is essential in running due to the risk of overuse injury development. Tailoring running shoes to individual needs may be a promising strategy to reduce this risk. Novel manufacturing processes allow the production of individualised running shoes that incorporate features that meet individual biomechanical and experiential needs. However, specific ways to individualise footwear to reduce injury risk are poorly understood. Therefore, this scoping review provides an overview of (1) footwear design features that have the potential for individualisation; and (2) the literature on the differential responses to footwear design features between selected groups of individuals. These purposes focus exclusively on reducing the risk of overuse injuries. We included studies in the English language on adults that analysed: (1) potential interaction effects between footwear design features and subgroups of runners or covariates (e.g., age, sex) for running-related biomechanical risk factors or injury incidences; (2) footwear comfort perception for a systematically modified footwear design feature. Most of the included articles (n = 107) analysed male runners. Female runners may be more susceptible to footwear-induced changes and overuse injury development; future research should target more heterogonous sampling. Several footwear design features (e.g., midsole characteristics, upper, outsole profile) show potential for individualisation. However, the literature addressing individualised footwear solutions and the potential to reduce biomechanical risk factors is limited. Future studies should leverage more extensive data collections considering relevant covariates and subgroups while systematically modifying isolated footwear design features to inform footwear individualisation.
Supplementary Information
The online version contains supplementary material available at 10.1186/s13102-023-00760-x.
... Heel height may also affect the sagittal plane torques and range of motion of the ankle through stance 3,6,7 . It is unclear if these effects are direct modifications of ankle dynamics or secondary outcomes of changes in stride length 8 . ...
Shoes alter the evolved biomechanics of the foot, potentially affecting running kinematics and kinetics that can in turn influence injury and performance. An important feature of conventional running shoes is heel height, whose effects on foot and ankle biomechanics remain understudied. Here, we investigate the effects of 6 -- 26 mm increases in heel height on ankle dynamics in 8 rearfoot strike runners who ran barefoot and in minimal shoes with added heels. We predicted higher heels would lead to greater frontal plane ankle torques due to the increased vertical moment arm of the mediolateral ground reaction force. Surprisingly, the torque increased in minimal shoes with no heel elevation, but then decreased with further increases in heel height due to changes in foot posture that are probably a strategy to compensate for potentially injurious ankle torques. We also found that increasing heel heights caused a large increase in the ankle plantarflexion velocity at heel strike, which we explain using a passive collision model. Our results highlight how running in minimal shoes may be significantly different from barefoot running due to complex interactions between proprioception and biomechanics that also permit runners to compensate for modifications to shoe design, more in the frontal than sagittal planes.
... Concerning the general effects of midsole geometries on BRFs, most of the included studies have addressed the effect of midsole geometry on ground reaction force parameters. An increase in heel-toe drop has been reported to reduce vertical GRF loading rates (72)(73)(74)(75). Mixed results have been reported for midsole thickness, for which one study found lower vertical loading rates in thicker than thinner midsoles (76), whereas another study could not identify any differences (77). ...
Running shoes were categorized either as motion control, cushioned, or minimal footwear in the past. Today, these categories blur and are not as clearly defined. Moreover, with the advances in manufacturing processes, it is possible to create individualized running shoes that incorporate features that meet individual biomechanical and experiential needs. However, specific ways to individualize footwear to reduce individual injury risk are poorly understood. Therefore, the purpose of this scoping review was to provide an overview of (1) footwear design features that have the potential for individualization; (2) human biomechanical variability as a theoretical foundation for individualization; (3) the literature on the differential responses to footwear design features between selected groups of individuals. These purposes focus exclusively on reducing running-related risk factors for overuse injuries. We included studies in the English language on adults that analyzed: (1) potential interaction effects between footwear design features and subgroups of runners or covariates (e.g., age, gender) for running-related biomechanical risk factors or injury incidences; (2) footwear perception for a systematically modified footwear design feature. Most of the included articles (n = 107) analyzed male runners. Several footwear design features (e.g., midsole characteristics, upper, outsole profile) show potential for individualization. However, the overall body of literature addressing individualized footwear solutions and the potential to reduce biomechanical risk factors is limited. Future studies should leverage more extensive data collections considering relevant covariates and subgroups while systematically modifying isolated footwear design features to inform footwear individualization.
... However, based on that, the direction of force was not measurable with the current setup, it is possible that the peak value, due to the forward inclined foot when using the high riser height, also creates a propulsive force. This would be comparable to the potential effect of heel to toe drop in running shoes (Richert et al., 2019;Mo et al., 2020). It was demonstrated that foot angle is well comparable for certain combinations of gradient and riser height (8% low vs. 24% medium, or 8% medium vs. 16% high, or 16% medium vs. 24% high). ...
In ski mountaineering, equipment and its interaction with the exercising human plays an important role. The binding, as the crucial connection between boot and ski, must ensure safe fixation during downhill skiing and a free moving heel when walking uphill. Uphill, the binding offers the possibility to adopt the height of the heel (riser height) to personal preferences and the steepness of the ascent. This possible adjustment and its influence on various biomechanical parameters are the focus of this work. For this study, 19 male leisure ski mountaineers were tested on a treadmill, ascending at a fixed submaximal speed (3.9 ± 0.4 km·h−1) at 8, 16, and 24% gradient and with three heel riser heights, low (0 cm), medium (3.0 cm) and high (5.3 cm). The applied biomechanical measurement systems included a 3D motion capture system in sagittal plane, pressure insoles, a with strain gauges instrumented pole, spirometry and a comfort scale. Step length and step frequency were influenced by the riser height and the gradient (p ≤ 0.001). The high riser height decreased the step length by 5% compared to the low riser height over all tested gradients, while steps were 9.2% longer at the 24% gradient compared to the 8% gradient over all three riser heights. The high riser height revealed a force impulse of the pole 13% lower than using the low riser height (p < 0.001). Additionally, the high riser height reduced the range of motion of the knee joint and the ankle joint compared to the low riser height (p < 0.001). Therefore, advantageous settings can be derived, with the low riser height creating proper range of motion for ankle, knee and hip joint and higher propulsion via the pole at 8%, while higher riser heights like the medium setting do so at steeper gradients. These findings are in line with the conducted comfort scale. We would not recommend the highest riser height for the analyzed gradients in this study, but it might be an appropriate choice for higher gradients.
... Several authors from the biomechanics view had researched the effect of different HTDs. It was reported that a 4mm HTD induced a higher vertical loading rate than 8 and 12 mm HTD, and the lower limb biomechanics performance of a 4-mm HTD was not similar to barefoot running (Richert et al., 2019). During the investigation, there was no specific adaptation in spatiotemporal variables and kinematics between the three kinds of shoes (0 mm HTD, 6 mm HTD, and 10 mm HTD) (Malisoux et al., 2017). ...
The study aimed to research the effects of innovative running shoes (a high heel-to-toe drop and special structure of midsole) on the biomechanics of the lower limbs and perceptual sensitivity in female runners. Fifteen healthy female runners were recruited to run through a 145-m runway with planted force plates at one peculiar speed (3.6 m/s ± 5%) with two kinds of shoe conditions (innovative running shoes vs. normal running shoes) while getting biomechanical data. The perception of shoe characteristics was assessed simultaneously through a 15-cm visual analog scale. The statistical parametric mapping technique calculated the time-series parameters. Regarding 0D parameters, the ankle dorsiflexion angle of innovative running shoes at touchdown was higher, and the peak dorsiflexion angle, range of motion, peak dorsiflexion velocity, and plantarflexion moment on the metatarsophalangeal joint of innovative running shoes during running were significantly smaller than those of normal running shoes (all p < 0.001). In addition, the braking phase and the time of peak vertical force 1 of innovative running shoes were found to be longer than those of normal running shoes (both p < 0.05). Meanwhile, the average vertical loading rate 1, peak vertical loading rate 1, peak braking force, and peak vertical force 1 in the innovative running shoes were lower than those of the normal running shoes during running (both p < 0.01). The statistical parametric mapping analysis exhibited a higher ankle dorsiflexion angle (0–4%, p < 0.05), a smaller knee internal rotation angle (0–6%, p < 0.05) (63–72%, p < 0.05), a decreased vertical ground reaction force (11–17%, p = 0.009), and braking anteroposterior ground reaction force (22–27%, p = 0.043) for innovative running shoes than normal running shoes. Runners were able to perceive the cushioning of innovative running shoes was better than that of normal running shoes. These findings suggested combining the high offset and structure of the midsole would benefit the industrial utilization of shoe producers in light of reducing the risk of running injuries for female runners.
... However, this condition is still debated because there is no clear evidence that high cushioning can reduce the impact peak [11]. Furthermore, different HTD can induce different running biomechanics such as an increased vertical loading rate in low HTD [12], changes in the foot inclination angle and therefore, changes in the running biomechanics [13]. ...
Simple Summary
Running is a physical activity practiced by many people to maintain good levels of movement. Recreational runners commonly strike the ground with the postero–lateral zone of the foot, which may be associated with a higher biomechanical load on the lower limb, called impact peak. Different running shoes with specific cushioning are available to overcome the biomechanical load, e.g., shoes with a thickness difference between the forefoot and heel parts of the sole, called heel-to-toe drop. Analyzing the running pattern of recreational runners may be challenging because biomechanics laboratories mainly analyze these characteristics in individuals with visible alterations. To overcome these limitations, we employed a 3D markerless system; furthermore, we investigated footwear use. These parameters were studied to understand the behavior of those runners with and without a higher impact peak. Thirty participants underwent a running analysis and a questionnaire about their footwear. The study’s main finding highlighted kinematic and spatiotemporal differences between the runners presenting a higher impact peak and those without it. Furthermore, we observed that runners without an impact peak prefer shoes with a lower heel-to-toe drop, while the other group prefers shoes with a higher heel-to-toe drop. Investigating biomechanics characteristics is essential to reduce possible injury.
Abstract
Running is a physical activity and the investigation of its biomechanical aspects is crucial both to avoid injuries and enhance performance. Recreational runners may be liable to increased stress over the body, particularly to lower limb joints. This study investigates the different running patterns of recreational runners by analyzing characteristics of the footwear impact peak, spatiotemporal, and kinematic parameters among those that present with a peak impact and those that do not, with a 3D markerless system. Thirty recreational runners were divided into two groups: impact peak group (IP) (n = 16) and no impact peak group (n = 14) (n-IP). Kinematic and spatiotemporal parameters showed a large Cohen’s d effect size between the groups. The mean hip flexion was IP 40.40° versus n-IP 32.30° (d = −0.82). Hip extension was IP 30.20° versus n-IP 27.70° (d = −0.58), and ankle dorsiflexion was IP 20.80°, versus n-IP 13.37° (d = −1.17). Stride length was IP 117.90 cm versus n-IP 105.50 cm (d = −0.84). Steps per minute was IP group 170 spm, versus n-IP 163 spm (d = −0.51). The heel-to-toe drop was mainly 10–12 mm for the IP group and 4–6 mm for the n-IP group. Recreational runners whose hip extension is around 40°, ankle dorsiflexion around 20°, and initial foot contact around 14°, may be predisposed to the presence of an impact peak.
... HTD, as a main feature of shoe design, was associated with alterations of lower limb biomechanics. Reduced HTD led to a transition of the foot strike pattern from RFS to FFS or MFS and changes of ankle and knee joints kinematics and kinetics (Horvais and Samozino 2013;Lee et al., 2013;Richert et al., 2019). As for the injury risk, although the injury risk among all runners was not changed, lower HTD shoes were associated with the lower injury risk among occasional runners, but the higher injury risk among regular runners (Malisoux et al., 2016). ...
With the increased popularity of running, many studies have been conducted into footwears that are highly related to running performance and running-related injuries. Previous studies investigated different shoe types and running shoes with different heel-to-toe drops (HTDs). However, no research was found in investigating shoes with negative values with HTD. Therefore, the aim of this study was to determine the acute effect of HTD and running speed on lower limb biomechanics and strike pattern in recreational runners. Thirteen male recreational runners wearing shoes with two different HTDs (−8 and 8 mm) performed running at three different speeds (preferred speed [PS], 90% of PS, 110% of PS). Lower extremity kinematics and ground reaction forces were synchronously captured via Vicon motion analysis system and AMTI force platform. Strike index (SI), vertical average loading rate (VALR), vertical instantaneous loading rate (VILR), excursion, eversion duration, joint angles, and range of motion (ROM) of metatarsophalangeal (MTP), ankle, knee, and hip joints were calculated. Joint angles during the entire stance phase were analyzed applying the statistical nonparametric mapping (SnPM) method. SI and VILR in shoes with −8 mm HTD significantly increased by 18.99% and 31.836 BW/s compared to those with 8 mm HTD (SI: p = 0.002; VILR: p < 0.001). Significant alterations of ROM occurred in the MTP, ankle, and knee joints (p < 0.05), and HTD factor primarily accounted for these changes. Joint angles (MTP, knee, and hip) during the entire stance phase altered due to HTD and speed factors. Running speed primarily influenced the kinematics parameters of knee and hip joints, increasing knee angles in the frontal plane and hip angle in the horizontal plane at PS (p > 0.05). Compared to shoes with 8 mm HTD, shoes with −8 mm HTD may be useful to storage and return energy because of the increased ROM of MTP in the sagittal plane. Besides, forefoot strike gait retraining was recommended before transition from normal running shoes to running shoes with −8 mm HTD.
... Minimalist running footwear, a low heel-to-toe drop, have been believed that it could reduce running-related injuries by encouraging to midfoot or forefoot strike pattern (Lieberman et al., 2010). However, there are research revealed that running with a low heel-to-toe drop did not lead to similar lower limb biomechanics as barefoot running, increase in vertical loading rate and be associated with a higher injury risk in regular runners (Richert, Stein, Ringhof & Stetter, 2019;Malisoux, Chambon, Urhausen & Theisen, 2016). The cushioning system has been believed that it would protect the runner against consequences of repetitive high-load shock. ...
Technology is being used in various fields, even in sport area with the purposes of maximizing the potential of athletes and to reduce or prevent injuries. However, a number of studies have shown that the incidence of sport’s injury has not declined as it should be. New technology would be promoted to create new running footwear which enhances the elite athletes’ performance, but the consideration should expand to those who are not an elite.
... stack height) of the sole in the heel versus the forefoot regions. Recent research on the biomechanical effects of offset have limited applicability because of a lack of consensus on a precise definition of offset or a reliable and valid method for measuring it (Chambon et al., 2015;Mo et al., 2020;Richert et al., 2019). ...
The footwear market contains a wide variety of running shoe solutions aiming at optimizing performance and minimizing injuries. Stack height is one of the most highly discussed design features of running shoes, but its effects are not yet well understood. This study investigated the effects of different shoes differing mainly in their stack heights (High: 50 mm, Medium: 35 mm and Low: 27 mm) on running style and stability during treadmill running at 10 and 15 km/h. A total of 17 healthy experienced runners participated. The kinematic data were recorded with a 3D motion capturing system. The running style was investigated with duty factor (DF) and leg length normalized to step frequency (SFnorm). Additionally, the ratio of landing to take-off duration, the lower body joint angle time series in the sagittal and frontal planes, the vertical center of mass oscillation (COMosc), and the stiffness parameters (kver and kleg) were compared for different conditions. The stability was analyzed using linear (i.e., discrete frontal ankle parameters) and nonlinear methods (i.e., Maximum Lyapunov Exponent for local dynamic stability of head, trunk, hip, and foot, and detrended fluctuation analysis of stride time). High resulted in longer ground contact relative to stride time (i.e., DF) compared to Low. The higher the stack height, the higher was the COMosc. Furthermore, High led to a longer foot eversion during stance compared to Medium. In addition, the local dynamic stability of the hip decreased with High in comparison with Low. The higher stack heights (≥35 mm) led to a lower SFnorm at 15 km/h but not at 10 km/h. The remaining shoe effects were independent of running speed. Findings showed that changes in stack height can affect running style. Furthermore, the highest stack height resulted in changes related with instabilities (i.e., longer foot eversion and lower hip dynamic stability) which may be a critical issue in terms of injuries and performance. However, this study did not include joint load analysis or running performance measures such as VO2. Future studies may benefit from combination of analysis approaches to better understand stack height effects on running injuries and performance.
Previous studies on gender differences in running biomechanics have predominantly been limited to joint angles and have not investigated a potential influence of footwear condition. This study shall contribute to closing this gap. Lower body biomechanics of 37 recreational runners (19 f, 18 m) were analysed for eight footwear and two running speed conditions. Presenting the effect size Cliff’s Delta enabled the interpretation of gender differences across a variety of variables and conditions. Known gender differences such as a larger range of hip movement in female runners were confirmed. Further previously undiscovered gender differences in running biomechanics were identified. In women, the knee extensors are less involved in joint work. Instead, compared to men, the supinators contribute more to deceleration and the hip abductors to acceleration. In addition to differences in extent, women also show a temporal delay within certain variables. For the foot, ankle and shank, as well as for the distribution of joint work, gender differences were found to be dependent on footwear condition, while sagittal pelvis and non-sagittal hip and thigh kinematics are rather consistent. On average, smaller gender differences were found for an individual compared to a uniform running speed. Future studies on gender differences should consider the influence of footwear and running speed and should provide an accurate description of the footwear condition used. The findings of this study could be used for the development of gender-specific running shoes and sports and medical products and provide a foundation for the application of smart wearable devices in gender-specific training and rehabilitation.
Shoes affect the evolved biomechanics of the foot, potentially affecting running kinematics and kinetics that can in turn influence injury and performance. An important feature of conventional running shoes is heel height, whose effects on foot and ankle biomechanics remain understudied. Here, we investigate the effects of 6–26 mm increases in heel height on ankle dynamics in 8 rearfoot strike runners who ran barefoot and in minimal shoes with added heels. We predicted higher heels would lead to greater frontal plane ankle torques due to the increased vertical moment arm of the mediolateral ground reaction force. Surprisingly, the torque increased in minimal shoes with no heel elevation, but then decreased with further increases in heel height due to changes in foot posture. We also found that increasing heel height caused a large increase in the ankle plantarflexion velocity at heel strike, which we explain using a passive collision model. Our results highlight how running in minimal shoes may be significantly different from barefoot running due to complex interactions between proprioception and biomechanics that also permit runners to compensate for modifications to shoe design, more in the frontal than sagittal planes.
There is debate and confusion over how to evaluate the biomechanical effects of running shoe design. Here we use an evolutionary perspective to analyze how key design features of running shoes alter the evolved biomechanics of the foot, creating a range of tradeoffs in force production and transmission that may affect performance and vulnerability to injury.
This review aimed to synthesise the methods for assessing and reporting footwear characteristics among studies evaluating the effect of footwear on running biomechanics. Electronic searches of Scopus®, EBSCO, PubMed®, ScienceDirect®, and Web of Science® were performed to identify original research articles of the effect of running footwear on running biomechanics published from 1st January 2015 to 7th October 2020. Risk of bias among included studies was not assessed. Results were presented via narrative synthesis. Eligible studies compared the effect of two or more footwear conditions in adult runners on a biomechanical parameter. Eighty-seven articles were included and data from 242 individual footwear were extracted. Predominantly, studies reported footwear taxonomy (i.e., classification) and manufacturer information, however omitted detail regarding the technical specifications of running footwear and did not use validated footwear reporting tools. There is inconsistency among contemporary studies in the methods by which footwear characteristics are assessed and reported. These findings point towards a need for consensus regarding the reporting of these characteristics within biomechanical studies to facilitate the conduct of systematic reviews and meta-analyses pertaining to the effect of running footwear on running biomechanics.
Background
While minimalist running shoes may have an influence on running biomechanics and on the incidence of overuse injuries, the term "minimalist" is currently used without standardisation. The objectives of this study were to reach a consensus on a standard definition of minimalist running shoes, and to develop and validate a rating scale that could be used to determine the degree of minimalism of running shoes, the Minimalist Index (MI).
Methods
For this modified Delphi study, 42 experts from 11 countries completed four electronic questionnaires on an optimal definition of minimalist shoes and on elements to include within the MI. Once MI was developed following consensus, 85 participants subjectively ranked randomly assigned footwear models from the most to the least minimalist and rated their degree of minimalism using visual analog scales (VAS), before evaluating the same footwear models using MI. A subsample of thirty participants reassessed the same shoes on another occasion. Construct validity and inter- and intra-rater reliability (intraclass correlation coefficients [ICC]; Gwet's AC1) of MI were evaluated.
Results
The following definition of minimalist shoes was agreed upon by 95 % of participants: "Footwear providing minimal interference with the natural movement of the foot due to its high flexibility, low heel to toe drop, weight and stack height, and the absence of motion control and stability devices". Characteristics to be included in MI were weight, flexibility, heel to toe drop, stack height and motion control/stability devices, each subscale carrying equal weighing (20 %) on final score. Total MI score was highly correlated with VAS (r = 0.91). A significant rank effect (p < 0.001) confirmed the MI's discriminative validity. Excellent intra- and inter-rater reliability was found for total MI score (ICC = 0.84-0.99) and for weight, stack height, heel to toe drop and flexibility subscales (AC1 = 0.82-0.99), while good inter-rater reliability was found for technologies (AC1 = 0.73).
Conclusion
This standardised definition of minimalist shoes developed by an international panel of experts will improve future research on minimalist shoes and clinical recommendations. MI's adequate validity and reliability will allow distinguishing running shoes based on their degree of minimalism, and may help to decrease injuries related to footwear transition.
To date it has been thought that shoe midsole hardness does not affect vertical impact peak forces during running. This conclusion is based partially on results from experimental data using homogeneous samples of participants that found no difference in vertical impact peaks when running in shoes with different midsole properties. However, it is currently unknown how apparent joint stiffness is affected by shoe midsole hardness. An increase in apparent joint stiffness could result in a harder landing, which should result in increased vertical impact peaks during running. The purpose of this study was to quantify the effect of shoe midsole hardness on apparent ankle and knee joint stiffness and the associated vertical ground reaction force for age and sex subgroups during heel-toe running. 93 runners (male and female) aged 16-75 years ran at 3.33 ± 0.15 m/s on a 30 m-long runway with soft, medium and hard midsole shoes. The vertical impact peak increased as the shoe midsole hardness decreased (mean(SE); soft: 1.70BW(0.03), medium: 1.64BW(0.03), hard: 1.54BW(0.03)). Similar results were found for the apparent ankle joint stiffness where apparent stiffness increased as the shoe midsole hardness decreased (soft: 2.08BWm/º x 100 (0.05), medium: 1.92 BWm/º x 100 (0.05), hard: 1.85 BWm/º x 100 (0.05)). Apparent knee joint stiffness increased for soft (1.06BWm/º x 100 (0.04)) midsole compared to the medium (0.95BWm/º x 100 (0.04)) and hard (0.96BWm/º x 100 (0.04)) midsoles for female participants. The results from this study confirm that shoe midsole hardness can have an effect on vertical impact force peaks and that this may be connected to the hardness of the landing. The results from this study may provide useful information regarding the development of cushioning guidelines for running shoes.
Abstract Despite the growing interest in minimalist shoes, no studies have compared the efficacy of different types of minimalist shoe models in reproducing barefoot running patterns and in eliciting biomechanical changes that make them differ from standard cushioned running shoes. The aim of this study was to investigate the acute effects of different footwear models, marketed as "minimalist" by their manufacturer, on running biomechanics. Six running shoes marketed as barefoot/minimalist models, a standard cushioned shoe and the barefoot condition were tested. Foot-/shoe-ground pressure and three-dimensional lower limb kinematics were measured in experienced rearfoot strike runners while they were running at 3.33 m · s(-1) on an instrumented treadmill. Physical and mechanical characteristics of shoes (mass, heel and forefoot sole thickness, shock absorption and flexibility) were measured with laboratory tests. There were significant changes in foot strike pattern (described by the strike index and foot contact angle) and spatio-temporal stride characteristics, whereas only some among the other selected kinematic parameters (i.e. knee angles and hip vertical displacement) changed accordingly. Different types of minimalist footwear models induced different changes. It appears that minimalist footwear with lower heel heights and minimal shock absorption is more effective in replicating barefoot running.
Purpose
Minimalist running shoes are designed to induce a foot strike made more with the forepart of the foot. The main changes made on minimalist shoe consist in decreasing the height difference between fore and rear parts of the sole (drop). Barefoot and shod running have been widely compared on overground or treadmill these last years, but the key characteristic effects of minimalist shoes have been yet little studied. The purpose of this study is to find whether the shoe drop has the same effect regardless of the task: overground or treadmill running.
Methods
Twelve healthy male subjects ran with three shoes of different drops (0, 4, 8 mm) and barefoot on a treadmill and overground. Vertical ground reaction force (vGRF) (transient peak and loading rate) and lower limb kinematics (foot, ankle and knee joint flexion angles) were observed.
Results
Opposite footwear effects on loading rate between the tasks were observed. Barefoot running induced higher loading rates during overground running than the highest drop condition, while it was the opposite during treadmill running. Ankle plantar flexion and knee flexion angles at touchdown were higher during treadmill than overground running for all conditions, except for barefoot which did not show any difference between the tasks.
Conclusions
Shoe drop appears to be a key parameter influencing running pattern, but its effects on vGRF differ depending on the task (treadmill vs. overground running) and must be considered with caution. Unlike shod conditions, kinematics of barefoot condition was not altered by treadmill running explaining opposite conclusions between the tasks.
Side-step cutting manoeuvres comprise the coordination between planting and non-planting legs. Increased shoe collar height is expected to influence ankle biomechanics of both legs and possibly respective cutting performance. This study examined the shoe collar height effect on kinematics and kinetics of planting and non-planting legs during an unanticipated side-step cutting. Fifteen university basketball players performed maximum-effort side-step cutting to the left 45° direction or a straight ahead run in response to a random light signal. Seven successful cutting trials were collected for each condition. Athletic performance, ground reaction force, ankle kinematics and kinetics of both legs were analysed using paired t-tests. Results indicated that high-collar shoes resulted in less ankle inversion and external rotation during initial contact for the planting leg. The high-collar shoes also exhibited a smaller ankle range of motion in the sagittal and transverse planes for both legs, respectively. However, no collar effect was found for ankle moments and performance indicators including cutting performance time, ground contact time, propulsion ground reaction forces and impulses. These findings indicated that high-collar shoes altered ankle positioning and restricted ankle joint freedom movements in both legs, while no negative effect was found for athletic cutting performance.
Increased impact characteristics are often cited as a cause of running injuries. One method that has been used to reduce impact characteristics is to increase the thickness of the midsole of running footwear with the intention of attenuating greater shock from the foot-ground collision. A second method that has been suggested is to run barefoot. The purpose of this study was to compare the impact characteristics of running footwear of different midsole thickness to a barefoot condition. Three-dimensional kinematic and kinetic data were collected as participants ran at their preferred running speed and at a fixed speed. Impact characteristics (impact peak, time to impact peak and vertical loading rate) were derived from the vertical ground reaction force component. Ankle and knee joint stiffness during the loading phase of support were derived from the change in moment divided by the change in angle. The impact parameters were statistically analyzed using a two-way, repeated measures ANOVA. There were no significant speed by footwear condition interactions. For impact peak, ankle stiffness and knee stiffness, there was no difference among the shod conditions but there were significant differences between the shod and barefoot conditions. Based on their strike index, participants in this study appeared to alter their footfall pattern from a rearfoot to a midfoot pattern when changing from running shod to barefoot. It may be concluded that the change in the impact characteristics is a result of changing footfall pattern rather than midsole thickness.
Barefoot or minimal footwear running is currently a highly debated topic among runners and researchers. Several footwear companies have developed minimal running footwear to simulate barefoot running but few studies have compared minimal footwear to barefoot and shoes during running. The primary goal of this study was to compare acute changes in three-dimensional (3D) ground reaction forces (GRFs) and lower limb kinematics and kinetics of habitually shod rearfoot strike (RFS) and forefoot strike (FFS) runners between minimal shoes (MSH), barefoot and neutral cushion running shoes (SH). Lower extremity joint biomechanical variables of RFS and FFS runners were analysed using a 3D motion capture system and a force platform during overground running in barefoot, MSH and running shoes. Barefoot and MSH showed a more anterior foot strike than shoes. The loading rate of the impact peak GRF was greater in barefoot and MSH than in shoes. MSH showed greater ankle plantarflexor moment and negative power in early stance compared to shoes, which indicates greater eccentric plantarflexor muscle involvement in MSH than in shoes. Running shoes had greater peak knee extensor moment, early stance eccentric knee power and late stance concentric knee power compared to MSH and barefoot indicating less knee joint involvement. The current findings only pertain to acute changes between shoe conditions, and therefore training interventions in minimal footwear are warranted to further understand the adaptation effects of shod to barefoot or RFS to FFS running on lower limb biomechanics and running performance.
Purpose: Running shoe cushioning research has focused widely on rearfoot (RF) characteristics, whereas forefoot (FF) characteristics have been rather neglected. However, altered cushioning may affect running biomechanics and respective subjective perception at RF and FF. Thus, this research compared the effect of running shoes with different midsole hardnesses at RF and FF. Methods: Twenty-eight heel-toe runners were tested in five experimental shoe conditions that featured three segmented EVA midsoles (RF, midfoot (MF), FF). Three conditions had the same midsole hardness at RF and FF (soft (SS), medium (MM), hard (HH)). Two conditions had different RF and FF midsole hardness (soft-RF/hard-FF (SH), hard-RF/soft-FF (HS)). All midsoles featured the same MF segment of medium hardness. Vertical ground reaction forces and lower extremity kinematics during stance, subjective cushioning of the heel-toe transition and the overall comfort were quantified. Data were analysed using Kolmogorov-Smirnov tests, repeated measures ANOVA, Bonferroni post-hoc tests (p < 0.05), and effect size analyses (pη2). Results: The consistent midsole shoe conditions showed increased maximum loading rates of impact and propulsion peaks from SS to HH. Respective maximum loading rates of SH were similarly to SS, and respective maximum loading rates for HS were similar to HH. Subjectively, the consistent midsole conditions were rated according to their mechanical properties and softer shoes were preferred over harder shoes. In the varied midsole shoe conditions, SH was perceived similar to SS, whereas HS was perceived similar to MM. Conclusion: The examined biomechanical variables were influenced almost entirely by respective RF cushioning properties. The hard FF did not negatively affect cushioning perception as long as the RF was soft. Combining a soft FF with a hard RF improved inferior cushioning perception associated with shoes being hard at RF and FF.
It is proposed to scale gait data (e.g. steplength, velocity, force, moment, work) by leg length and body mass. It is concluded that temporal parameters are affected by the scaling as well.
One correction: dimensionless power P^ = P/(m.g^3/2.l^1/2
A minimalist shoe could be described as a shoe with minimal midsole thickness at the heel (heel height) and a minimal positive difference between heel and metatarsus heights (drop). This study aimed to analyse the acute effect of heel height, drop and combinations of the two on the foot-strike pattern and running kinematics. Twelve healthy rearfoot males ran for 1 min at 3.9 and 4.7 m.s−1 on a treadmill in 16 different shoe conditions across which heel height and drop of the midsole varied independently. The foot-strike pattern was determined from high-speed video (240 Hz) by measuring the angle between the bottom of the foot and the horizontal at ground contact. Running kinematics were measured by an optical system (1000 Hz) placed on each side of the treadmill by which step frequency, duty factor, and leg and vertical stiffness were measured. Results showed that the lower the heel height and/or drop, the flatter the foot at ground contact, which characterised a foot-strike pattern tending toward a midfoot-strike pattern. Running kinematics was directly affected by drop but not by the heel height: drop was positively correlated to contact time and duty factor and negatively to flight time and leg stiffness. The foot-strike pattern alteration induced by a low drop and/or heel height was correlated to changes in running kinematics toward a running pattern previously associated with low foot–ground impact, and in turn to a ‘safer’ running pattern regarding stress fractures.
Impact reduction has become a factor of interest in the prevention of running-related injuries such as stress fractures. Currently, the midfoot strike pattern (MFS) is thought as a potential way to decrease impact. The purpose was to test the effects of two long-term interventions aiming to reduce impact during running via a transition to an MFS: a foot strike retraining versus a low-drop/low-heel height footwear. Thirty rearfoot strikers were randomly assigned to two experimental groups (SHOES and TRAIN). SHOES progressively wore low-drop/low-heel height shoes and TRAIN progressively adopted an MFS, over a 3-month period with three 30-min running sessions per week. Measurement sessions (pre-training, 1, 2 and 3 months) were performed during which subjects were equipped with three accelerometers on the shin, heel and metatarsals, and ran for 15 min on an instrumented treadmill. Synchronized acceleration and vertical ground reaction force signals were recorded. Peak heel acceleration was significantly lower as compared to pre-training for SHOES (-33.5 ± 12.8 % at 2 months and -25.3 ± 18.8 % at 3 months, p < 0.001), and so was shock propagation velocity (-12.1 ± 9.3 %, p < 0.001 at 2 months and -11.3 ± 4.6 %, p < 0.05 at 3 months). No change was observed for TRAIN. Important inter-individual variations were noted in both groups and reported pains were mainly located at the shin and calf. Although it induced reversible pains, low-drop/low-heel height footwear seemed to be more effective than foot strike retraining to attenuate heel impact in the long term.
Aim:
The purpose of this study was to determine the changes in running mechanics that occur when highly trained runners run barefoot and in a minimalist shoe, and specifically if running in a minimalist shoe replicates barefoot running.
Methods:
Ground reaction force data and kinematics were collected from 22 highly trained runners during overground running while barefoot and in three shod conditions (minimalist shoe, racing flat and the athlete's regular shoe). Three-dimensional net joint moments and subsequent net powers and work were computed using Newton-Euler inverse dynamics. Joint kinematic and kinetic variables were statistically compared between barefoot and shod conditions using a multivariate analysis of variance for repeated measures and standardised mean differences calculated.
Results:
There were significant differences between barefoot and shod conditions for kinematic and kinetic variables at the knee and ankle, with no differences between shod conditions. Barefoot running demonstrated less knee flexion during midstance, an 11% decrease in the peak internal knee extension and abduction moments and a 24% decrease in negative work done at the knee compared with shod conditions. The ankle demonstrated less dorsiflexion at initial contact, a 14% increase in peak power generation and a 19% increase in the positive work done during barefoot running compared with shod conditions.
Conclusions:
Barefoot running was different to all shod conditions. Barefoot running changes the amount of work done at the knee and ankle joints and this may have therapeutic and performance implications for runners.
Background: Barefoot running has been the subject of much attention in footwear biomechanics literature, based on the supposition that it serves to reduce the occurrence of overuse injuries in comparison to conventional shoe models. This consensus has led footwear manufacturers to develop shoes that aim to mimic the mechanics of barefoot locomotion. Objectives: This study compared the impact kinetics and three-dimensional (3-D) joint angular kinematics observed while running barefoot, in conventional cushioned running shoes and in shoes designed to integrate the perceived benefits of barefoot locomotion. The aim of the current investigation was therefore to determine whether differences in impact kinetics exist between the footwear conditions and whether shoes that aim to simulate barefoot movement patterns can closely mimic the 3-D kinematics of barefoot running. Method: Twelve participants ran at 4.0?m s?1 (±5%) in each footwear condition. Angular joint kinematics from the hip, knee and ankle in the sagittal, coronal and transverse planes were measured using an eight-camera motion analysis system. In addition, simultaneous tibial acceleration and ground reaction forces were obtained. Impact parameters and joint kinematics were subsequently compared using repeated-measures analyses of variance (ANOVAs). Results: The kinematic analysis indicated that, in comparison to the conventional and barefoot-inspired shoes, running barefoot was associated with significantly greater plantar?flexion at footstrike and range of motion to peak dorsiflexion. Furthermore, the kinetic analysis revealed that, compared to the conventional footwear, impact parameters were significantly greater in the barefoot condition. Conclusions: This study suggests that barefoot running is associated with impact kinetics linked to an increased risk of overuse injury when compared to conventional shod running. Furthermore, the mechanics of the shoes that aim to simulate barefoot movement patterns do not seem to closely mimic the kinematics of barefoot locomotion.
Evidence for preventive strategies to lessen running injuries is needed as these occur in 40%-50% of runners on an annual basis. Many factors influence running injuries, but strong evidence for prevention only exists for training modification primarily by reducing weekly mileage. Two anatomical factors - cavus feet and leg length inequality - demonstrate a link to injury. Weak evidence suggests that orthotics may lessen risk of stress fracture, but no clear evidence proves they will reduce the risk of those athletes with leg length inequality or cavus feet. This article reviews other potential injury variables, including strength, biomechanics, stretching, warm-up, nutrition, psychological factors, and shoes. Additional research is needed to determine whether interventions to address any of these will help prevent running injury.
Humans have engaged in endurance running for millions of years, but the modern running shoe was not invented until the 1970s. For most of human evolutionary history, runners were either barefoot or wore minimal footwear such as sandals or moccasins with smaller heels and little cushioning relative to modern running shoes. We wondered how runners coped with the impact caused by the foot colliding with the ground before the invention of the modern shoe. Here we show that habitually barefoot endurance runners often land on the fore-foot (fore-foot strike) before bringing down the heel, but they sometimes land with a flat foot (mid-foot strike) or, less often, on the heel (rear-foot strike). In contrast, habitually shod runners mostly rear-foot strike, facilitated by the elevated and cushioned heel of the modern running shoe. Kinematic and kinetic analyses show that even on hard surfaces, barefoot runners who fore-foot strike generate smaller collision forces than shod rear-foot strikers. This difference results primarily from a more plantarflexed foot at landing and more ankle compliance during impact, decreasing the effective mass of the body that collides with the ground. Fore-foot- and mid-foot-strike gaits were probably more common when humans ran barefoot or in minimal shoes, and may protect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners.
There are evidences to suggest that wearing footwear constrains the natural barefoot motion during locomotion. Unlike prior studies that deduced foot motions from shoe sole displacement parameters, the aim of this study was to examine the effect of footwear motion on forefoot to rearfoot relative motion during walking and running. The use of a multi-segment foot model allowed accurate both shoe sole and foot motions (barefoot and shod) to be quantified. Two pairs of identical sandals with different midsole hardness were used. Ten healthy male subjects walked and ran in each of the shod condition. The results showed that for barefoot locomotion there was more eversion of the forefoot and it occurred faster than for shod locomotion. In this later condition, the range of eversion was reduced by 20% and the rate of eversion in late stance by 60% in comparison to the barefoot condition. The sole constrained both the torsional (eversion/inversion) and adduction range of motion of the foot. Interestingly, during the push-off phase of barefoot locomotion the rate and direction of forefoot torsion varied between individuals. However, most subjects displayed a forefoot inversion direction of motion while shod. Therefore, this experiment showed that the shoes not only restricted the natural motion of the barefoot but also appeared to impose a specific foot motion pattern on individuals during the push-off phase. These findings have implications for the matching of footwear design characteristics to individual natural foot function.
The characteristics of the midsole were examined in four pairs of running shoes by a materials test. The variables of interest were the peak acceleration, time to peak acceleration and the kinetic energy absorbed. Ten subjects then ran at a recreational jogging pace (3.5 ms-1) barefoot and in the shoes. An accelerometer secured to the lower tibia was used to measure the peak acceleration and time to peak acceleration associated with footstrike. Subjects were also videoed and a kinematic analysis was undertaken at the knee and ankle joints. The results from the materials test showed that the shoes differed in their midsole characteristics, however, no significant differences (P > 0.05) were observed in the peak acceleration and time to peak acceleration during running in shoes. These variables were significantly greater in the barefoot running condition (P < 0.05), as compared with running in shoes. Small and subtle kinematic differences were observed between the barefoot and shoe conditions. It appears that the differences observed between the shoes in the materials test were not sufficient to elicit the kinematic changes observed between the barefoot and shoe conditions. It is suggested that runners operate within a 'kinetic bandwidth' when responding to impact stresses.
Objective:
Athletic shoes and mats are support surface interfaces composed of relatively soft compressible materials designed to protect against injuries occurring in sports through force of vertical impact. Impact remains high with their use because humans land harder with them. We hypothesize that this hard-landing strategy is an attempt by the user to improve stability, by compressing the material to a less destabilizing thinner-stiff variety. We tested this hypothesis by comparing impact and balance on materials consisting of ethyl-vinyl acetate (EVA) foams of varying stiffness, identical to that found in soles of athletic footwear.
Design:
Randomized-order, crossover trial, controlled comparison, blinded.
Setting:
Volunteers were selected from the general community.
Participants:
A random sample of 12 healthy men from the general population (mean age 30 years, SD +/- 6). Additional selection criteria were absence of disabilities influencing ability to walk, run, and balance, and no history of frequent falls.
Methods:
Impact testing and stability measures were performed on the same test day. Ground reaction forces were measured for ten barefoot footfalls. The protocol required stepping forward from perch to surface 4.5 cm below. Stability testing was performed with one-legged standing consisting of placing left foot on top of right for 30 sec, barefoot, eyes open, and gaze straight, with arms to side. Subjects confronted four surface conditions presented in random order: a bare rigid platform, and the platform covered with one of three 2.5-cm-thick materials.
Results:
Steady state vertical impact was a negative function of interface stiffness, with the softest interface producing the greatest vertical impact, and the stiffest interface the least vertical impact. Vertical impact and stability measures were also negatively related, with the strongest correlation obtained with the softest interface (r = -.87, p < .001). No relation between these variables was obtained for the rigid surface.
Conclusion:
Balance and vertical impact are closely related. This supports the hypothesis that landing hard on soft surfaces is an attempt to transform the interface into a form associated with improved stability. According to these findings, currently available sports shoes and mats are too soft and thick, and should be redesigned to protect the persons using them.
To provide an extensive and up to date database for specific running related injuries, across the sexes, as seen at a primary care sports medicine facility, and to assess the relative risk for individual injuries based on investigation of selected risk factors.
Patient data were recorded by doctors at the Allan McGavin Sports Medicine Centre over a two year period. They included assessment of anthropometric, training, and biomechanical information. A model was constructed (with odds ratios and their 95% confidence intervals) of possible contributing factors using a dependent variable of runners with a specific injury and comparing them with a control group of runners who experienced a different injury. Variables included in the model were: height, weight, body mass index, age, activity history, weekly activity, history of injury, and calibre of runner.
Most of the study group were women (54%). Some injuries occurred with a significantly higher frequency in one sex. Being less than 34 years old was reported as a risk factor across the sexes for patellofemoral pain syndrome, and in men for iliotibial band friction syndrome, patellar tendinopathy, and tibial stress syndrome. Being active for less than 8.5 years was positively associated with injury in both sexes for tibial stress syndrome; and women with a body mass index less than 21 kg/m(2) were at a significantly higher risk for tibial stress fractures and spinal injuries. Patellofemoral pain syndrome was the most common injury, followed by iliotibial band friction syndrome, plantar fasciitis, meniscal injuries of the knee, and tibial stress syndrome.
Although various risk factors were shown to be positively associated with a risk for, or protection from, specific injuries, future research should include a non-injured control group and a more precise measure of weekly running distance and running experience to validate these results.
The purpose of this study was to compare the kinematic and kinetic parameters of treadmill running to those of overground running.
Twenty healthy young subjects ran overground at their self-selected moderate running speed. Motion capture and ground reaction force (GRF) data for three strides of each limb were recorded and the subjects' average running speed was evaluated. The subjects then ran on an instrumented treadmill set to their average overground running speed while motion capture and GRF data were recorded. The kinematics (body segment orientations and joint angles) and kinetics (net joint moments and joint powers) for treadmill (15 consecutive gait cycles) and overground running (three cycles each limb) were calculated and compared.
The features of the kinematic and kinetic trajectories of treadmill gait were similar to those of overground gait. Statistically significant differences in knee kinematics,the peak values of GRF, joint moment, and joint power trajectories were identified.
Parameters measured with an adequate instrumented treadmill are comparable to but not directly equivalent to those measured for overground running. With such an instrument, it is possible to study the mechanics of running under well-controlled and reproducible conditions.
Treadmill-based analysis of running mechanics can be generalized to overground running mechanics, provided the treadmill surface is sufficiently stiff and belt speed is adequately regulated.
Background:
Modern running shoes are available in a wide range of heel-to-toe drops (ie, the height difference between the forward and rear parts of the inside of the shoe). While shoe drop has been shown to influence strike pattern, its effect on injury risk has never been investigated. Therefore, the reasons for such variety in this parameter are unclear.
Purpose:
The first aim of this study was to determine whether the drop of standard cushioned running shoes influences running injury risk. The secondary aim was to investigate whether recent running regularity modifies the relationship between shoe drop and injury risk.
Study design:
Randomized controlled trial; Level of evidence, 1.
Methods:
Leisure-time runners (N = 553) were observed for 6 months after having received a pair of shoes with a heel-to-toe drop of 10 mm (D10), 6 mm (D6), or 0 mm (D0). All participants reported their running activities and injuries (time-loss definition, at least 1 day) in an electronic system. Cox regression analyses were used to compare injury risk between the 3 groups based on hazard rate ratios (HRs) and their 95% CIs. A stratified analysis was conducted to evaluate the effect of shoe drop in occasional runners (<6 months of weekly practice over the previous 12 months) versus regular runners (≥6 months).
Results:
The overall injury risk was not different among the participants who had received the D6 (HR, 1.30; 95% CI, 0.86-1.98) or D0 (HR, 1.17; 95% CI, 0.76-1.80) versions compared with the D10 shoes. After stratification according to running regularity, low-drop shoes (D6 and D0) were found to be associated with a lower injury risk in occasional runners (HR, 0.48; 95% CI, 0.23-0.98), whereas these shoes were associated with a higher injury risk in regular runners (HR, 1.67; 95% CI, 1.07-2.62).
Conclusion:
Overall, injury risk was not modified by the drop of standard cushioned running shoes. However, low-drop shoes could be more hazardous for regular runners, while these shoes seem to be preferable for occasional runners to limit injury risk.
Objective:
This study aimed to investigate the associations between patellofemoral cartilage T1ρ and T2 relaxation times and knee flexion moment (KFM) and KFM impulse during gait.
Method:
Knee magnetic resonance (MR) images were obtained from 99 subjects with and without patellofemoral joint osteoarthritis (OA), using fast spin-echo, T1ρ and T2 relaxation time sequences. Patellar and trochlear cartilage relaxation times were computed for the whole cartilage, and superficial and deep layers (laminar analysis). Subjects also underwent 3D gait analysis. Peak KFM and KFM impulse were calculated during the stance phase. Linear regressions were used to examine whether cartilage relaxation times were associated with knee kinetics during walking while adjusting age, sex, BMI and walking speed.
Results:
Higher peak KFM and KFM impulse were significantly related to higher T1ρ and T2 relaxation times of the trochlear and patellar cartilage, with standardized regression coefficients ranging from 0.21 to 0.28. Laminar analysis showed that overall the superficial layer of patellofemoral cartilage showed stronger associations with knee kinetics. Subgroup analysis revealed that in subjects with patellofemoral joint OA, every standard deviation change in knee kinetics was related to greater increases in PFJ cartilage T1ρ and T2 (standardized coefficients: 0.29 to 0.41). Conversely, in subjects without OA, weaker relationships were observed between knee kinetics and PFJ cartilage T1ρ and T2.
Conclusions:
Our findings suggest that increased peak KFM and KFM impulse were related to worse cartilage health at the patellofemoral joint. This association is more prominent in superficial layer cartilage and cartilage with morphological lesions.
Purpose: This study investigated lower limb variability when trained runners wore a minimal shoe for the first time. It was hypothesised that initial lower limb variability would be decreased in the minimal shoe condition due to lack of familiarity. It was also hypothesised that variability would increase over time as runners become more familiar with the condition.Methods: Testing included three 10 minute treadmill running trials conducted in runner's own running shoes, a pair of minimal shoes followed by runner's own shoes again. The shoe order was selected so as to establish a baseline value of variability in a runner's most familiar shoes followed by a perturbation which was the inclusion of minimal shoes. Continuous Relative Phase (CRP) relationships and kinematic values at heel strike were determined which allowed lower limb variability to be quantified.Results: Kinematic variability values were not statistically different between runner's own shoes and minimal shoes. CRP relationships did not differ between minimal shoes and runner's own shoes or over time.Conclusions: Trained runners did not change lower limb variability while wearing minimal shoes for the first time. Lack of familiarity does not appear to affect lower limb variability. The footwear included in this research study had similar cushioning properties to traditional footwear but with a different construction which may relate to similar values found between conditions. Investigating how runners of different abilities transition to minimal footwear should be focused upon to reduce risk of injury.
Introduction: Research on minimal footwear hasn't utilised runners who habitually wear typical training footwear and therefore what adjustments to running patterns are made and how quickly they occur is unknown. Purpose: The purposes of this study were: 1) to investigate how kinematic patterns are adjusted while running barefoot and in footwear with systematic changes in shock attenuating material; and 2) to determine the time it takes for adjustments to occur when little is known about the footwear condition before running commences. Methods: Ten male heel-toe runners performed treadmill runs of 6 minutes in thin, medium, and thick footwear and barefoot. Participants ran immediately after putting shoes on to limit information about each footwear condition. Standard kinematics and acceleration signals were captured. Repeated measures analysis of variance (ANOVA) was utilised (p < 0.05) to determine differences across footwear conditions and time. Results: The foot was flatter at touchdown (due to a more vertical leg segment and more plantar flexion), the knee had reduced excursion, and stance times, eversion and tibial rotation excursions were greater in the thin footwear or when barefoot. Several variables were adjusted from the initial steps to later in the run. Acceleration standard deviations had more variability during initial steps than immediately following. Discussion: Many kinematic adjustments agreed with previous works though participants did not adopt a midfoot or forefoot strike pattern. Experimental design and participant knowledge and experiences may be contributing to discrepancies in footstrike patterns. Runners sensitive to eversion and tibial internal rotation should use caution when barefoot or in minimal footwear. Finally, the greatest kinematic changes occurred within the first six to eight steps, however more subtle changes continued throughout the six minute run.
Objectives
Minimalist running shoes have been proposed as an alternative to barefoot running. However, several studies have reported cases of forefoot stress fractures after switching from standard to minimalist shoes. Therefore, the aim of the current study was to investigate the differences in plantar pressure in the forefoot region between running with a minimalist shoe and running with a standard shoe in healthy female runners during overground running.
Design
Randomized crossover design
Methods
In-shoe plantar pressure measurements were recorded from eighteen healthy female runners. Peak pressure, maximum mean pressure, pressure time integral and instant of peak pressure were assessed for seven foot areas. Force time integral, stride time, stance time, swing time, shoe comfort and landing type were assessed for both shoe types. A linear mixed model was used to analyze the data.
Results
Peak pressure and maximum mean pressure were higher in the medial forefoot (respectively 13.5% and 7.46%), central forefoot (respectively 37.5% and 29.2%) and lateral forefoot (respectively 37.9% and 20.4%) for the minimalist shoe condition. Stance time was reduced with 3.81%. No relevant differences in shoe comfort or landing strategy were found.
Conclusion
Running with a minimalist shoe increased plantar pressure without a change in landing pattern. This increased pressure in the forefoot region might play a role in the occurrence of metatarsal stress fractures in runners who switched to minimalist shoes and warrants a cautious approach to transitioning to minimalist shoe use.
Although it could be perceived that there is extensive research on the impact attenuation characteristics of shoes, the approach and findings of researchers in this area are varied. This review aimed to clarify the effect of shoes on impact attenuation to the foot and lower leg and was limited to those studies that compared the shoe condition(s) with barefoot. A systematic search of the literature yielded 26 studies that investigated vertical ground reaction force, axial tibial acceleration, loading rate and local plantar pressures. Meta-analyses of the effect of shoes on each variable during walking and running were performed using the inverse variance technique. Variables were collected at their peak or at the impact transient, but when grouped together as previous comparisons have done, shoes reduced local plantar pressure and tibial acceleration, but did not affect vertical force or loading rate for walking. During running, shoes reduced tibial acceleration but did not affect loading rate or vertical force. Further meta-analyses were performed, isolating shoe type and when the measurements were collected. Athletic shoes reduced peak vertical force during walking, but increased vertical force at the impact transient and no change occurred for the other variables. During running, athletic shoes reduced loading rate but did not affect vertical force. The range of variables examined and variety of measurements used appears to be a reason for the discrepancies across the literature. The impact attenuating effect of shoes has potentially both adverse and beneficial effects depending on the variable and activity under investigation.
Running has evolved throughout history from a necessary form of locomotion to an athletic and recreational pursuit. During this transition, our barefoot ancestors developed footwear. By the late 1970s, running popularity surged, and footwear manufacturers developed the running shoe. Despite new shoe technology and expert advice, runners still face high injury rates, which have yet to decline. Recently, "minimalist" running, marked by a soft forefoot strike and shorter, quicker strides, has become increasingly popular within the running community. Biomechanical studies have suggested that these features of barefoot-style running may lead to a reduction in injury rates. After conducting more outcomes-based research, minimalist footwear and gait retraining may serve as new methods to reduce injuries within the running population.
The objective of the study was to investigate the adjustment of running mechanics by wearing five different types of running shoes on tartan compared to barefoot running on grass focusing on the gearing at the ankle and knee joints. The gear ratio, defined as the ratio of the moment arm of the ground reaction force (GRF) to the moment arm of the counteracting muscle tendon unit, is considered to be an indicator of joint loading and mechanical efficiency. Lower extremity kinematics and kinetics of 14 healthy volunteers were quantified three dimensionally and compared between running in shoes on tartan and barefoot on grass. Results showed no differences for the gear ratios and resultant joint moments for the ankle and knee joints across the five different shoes, but showed that wearing running shoes affects the gearing at the ankle and knee joints due to changes in the moment arm of the GRF. During barefoot running the ankle joint showed a higher gear ratio in early stance and a lower ratio in the late stance, while the gear ratio at the knee joint was lower during midstance compared to shod running. Because the moment arms of the counteracting muscle tendon units did not change, the determinants of the gear ratios were the moment arms of the GRF's. The results imply higher mechanical stress in shod running for the knee joint structures during midstance but also indicate an improved mechanical advantage in force generation for the ankle extensors during the push-off phase.
To determine the effect of modern-day running shoes on lower extremity joint torques during running.
Two-condition experimental comparison.
A 3-dimensional motion analysis laboratory.
A total of 68 healthy young adult runners (37 women) who typically run in running shoes.
All subjects ran barefoot and in the same type of stability running footwear at a controlled running speed. Three-dimensional motion capture data were collected in synchrony with ground reaction force data from an instrumented treadmill for each of the 2 conditions.
Peak 3-dimensional external joint torques at the hip, knee, and ankle as calculated through a full inverse dynamic model.
Increased joint torques at the hip, knee, and ankle were observed with running shoes compared with running barefoot. Disproportionately large increases were observed in the hip internal rotation torque and in the knee flexion and knee varus torques. An average 54% increase in the hip internal rotation torque, a 36% increase in knee flexion torque, and a 38% increase in knee varus torque were measured when running in running shoes compared with barefoot.
The findings at the knee suggest relatively greater pressures at anatomical sites that are typically more prone to knee osteoarthritis, the medial and patellofemoral compartments. It is important to note the limitations of these findings and of current 3-dimensional gait analysis in general, that only resultant joint torques were assessed. It is unknown to what extent actual joint contact forces could be affected by compliance that a shoe might provide, a potentially valuable design characteristic that may offset the observed increases in joint torques.
Treadmills are often used in research to analyse kinematic and physiological variables. The success of transfering the results to overground running depends on the comparability of the values between the two situations. The aim of the present study was to compare the kinematics and muscle activities in overground and treadmill running. Ten male physical education students with experience in treadmill running were asked to run with a speed of 4.0 and 6.0 m/s both overground and on a Woodway treadmill. The 3D-kinematics of the limbs were studied using a two camera video tracking system. Additionally the surface EMG of six lower limb muscles and the pattern of ground contact of the right foot was registered. Both the activities of the leg muscles and several kinematic variables showed systematic changes from overground to treadmill running. On the treadmill the subjects favoured a type of running that provided them with a higher level of security. The swing amplitude of the leg, the vertical displacement and the variance in vertical and horizontal velocity were lower in treadmill running. The angle between shoe sole and ground at foot impact was also lower and the forward lean of the upper body was higher in running on the treadmill compared with the overground mode. Most of the subjects reduced their step length and increased stride frequency in treadmill running. Furthermore, the contact time in treadmill running was shorter than for overground running. The above mentioned kinematic variables were significantly different (p < 0.05). The EMG patterns of the leg muscles were generally similar between overground and treadmill modes, but some minor differences could consistently be identified.
This study investigated spatio-temporal variables, ground reaction forces and sagittal and frontal plane kinematics during the stance phase of nine trained subjects running barefoot and shod at three different velocities (3.5, 4.5, 5.5 m s(-1)). Differences between conditions were detected with the general linear method (factorial model). Barefoot running is characterized by a significantly larger external loading rate than the shod condition. The flatter foot placement at touchdown is prepared in free flight, implying an actively induced adaptation strategy. In the barefoot condition, plantar pressure measurements reveal a flatter foot placement to correlate with lower peak heel pressures. Therefore, it is assumed that runners adopt this different touchdown geometry in barefoot running in an attempt to limit the local pressure underneath the heel. A significantly higher leg stiffness during the stance phase was found for the barefoot condition. The sagittal kinematic adaptations between conditions were found in the same way for all subjects and at the three running velocities. However, large individual variations were observed between the runners for the rearfoot kinematics.
Repetitive impacts encountered during locomotion may be modified by footwear and/or surface. Changes in kinematics may occur either as a direct response to altered mechanical conditions or over time as active adaptations.
: To investigate how midsole hardness, surface stiffness, and running duration influence running kinematics.
In the first of two experiments, 12 males ran at metabolic steady state under six conditions; combinations of midsole hardness (40 Shore A, 70 Shore A), and surface stiffness (100 kN x m, 200 kN x m, and 350 kN x m). In the second experiment, 10 males ran for 30 min on a 12% downhill grade. In both experiments, subjects ran at 3.4 m x s on a treadmill while 2-D hip, knee, and ankle kinematics were determined using high-speed videography (200 Hz). Oxygen cost and heart rate data were also collected. Kinematic adaptations to midsole, surface, and running time were studied.
Stance time, stride cycle time, and maximal knee flexion were invariant across conditions in each experiment. Increased midsole hardness resulted in greater peak ankle dorsiflexion velocity (P = 0.0005). Increased surface stiffness resulted in decreased hip and knee flexion at contact, reduced maximal hip flexion, and increased peak angular velocities of the hip, knee, and ankle. Over time, hip flexion at contact decreased, plantarflexion at toe-off increased, and peak dorsiflexion and plantarflexion velocity increased.
Lower-extremity kinematics adapted to increased midsole hardness, surface stiffness, and running duration. Changes in limb posture at impact were interpreted as active adaptations that compensate for passive mechanical effects. The adaptations appeared to have the goal of minimizing metabolic cost at the expense of increased exposure to impact shock.
Tibial stress fractures (TSF) are among the most serious running injuries, typically requiring 6-8 wk for recovery. This cross-sectional study was conducted to determine whether differences in structure and running mechanics exist between trained distance runners with a history of prior TSF and those who have never sustained a fracture.
Female runners with a rearfoot strike pattern, aged between 18 and 45 yr and running at least 32 km.wk(-1), were recruited for this study. Participants in the study were 20 subjects with a history of TSF and 20 age- and mileage-matched control subjects with no previous lower extremity bony injuries. Kinematic and kinetic data were collected during overground running at 3.7 m.s(-1) using a six-camera motion capture system, force platform, and accelerometer. Variables of interest were vertical impact peak, instantaneous and average vertical loading rates, instantaneous and average loading rates during braking, knee flexion excursion, ankle and knee stiffness, and peak tibial shock. Tibial varum was measured in standing. Tibial area moment of inertia was calculated from tibial x-ray studies for a subset of runners.
The TSF group had significantly greater instantaneous and average vertical loading rates and tibial shock than the control group. The magnitude of tibial shock predicted group membership successfully in 70% of cases.
These data indicate that a history of TSF in runners is associated with increases in dynamic loading-related variables.
In 1995 the American College of Sports Medicine and the Centers for Disease Control and Prevention published national guidelines on Physical Activity and Public Health. The Committee on Exercise and Cardiac Rehabilitation of the American Heart Association endorsed and supported these recommendations. The purpose of the present report is to update and clarify the 1995 recommendations on the types and amounts of physical activity needed by healthy adults to improve and maintain health. Development of this document was by an expert panel of scientists, including physicians, epidemiologists, exercise scientists, and public health specialists. This panel reviewed advances in pertinent physiologic, epidemiologic, and clinical scientific data, including primary research articles and reviews published since the original recommendation was issued in 1995. Issues considered by the panel included new scientific evidence relating physical activity to health, physical activity recommendations by various organizations in the interim, and communications issues. Key points related to updating the physical activity recommendation were outlined and writing groups were formed. A draft manuscript was prepared and circulated for review to the expert panel as well as to outside experts. Comments were integrated into the final recommendation. PRIMARY RECOMMENDATION: To promote and maintain health, all healthy adults aged 18 to 65 yr need moderate-intensity aerobic (endurance) physical activity for a minimum of 30 min on five days each week or vigorous-intensity aerobic physical activity for a minimum of 20 min on three days each week. [I (A)] Combinations of moderate- and vigorous-intensity activity can be performed to meet this recommendation. [IIa (B)] For example, a person can meet the recommendation by walking briskly for 30 min twice during the week and then jogging for 20 min on two other days. Moderate-intensity aerobic activity, which is generally equivalent to a brisk walk and noticeably accelerates the heart rate, can be accumulated toward the 30-min minimum by performing bouts each lasting 10 or more minutes. [I (B)] Vigorous-intensity activity is exemplified by jogging, and causes rapid breathing and a substantial increase in heart rate. In addition, every adult should perform activities that maintain or increase muscular strength and endurance a minimum of two days each week. [IIa (A)] Because of the dose-response relation between physical activity and health, persons who wish to further improve their personal fitness, reduce their risk for chronic diseases and disabilities or prevent unhealthy weight gain may benefit by exceeding the minimum recommended amounts of physical activity. [I (A)].
- Cohen J