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Effects of Step Rate Manipulation on Joint Mechanics during Running
Abstract
the objective of this study was to characterize the biomechanical effects of step rate modification during running on the hip, knee, and ankle joints so as to evaluate a potential strategy to reduce lower extremity loading and risk for injury.
three-dimensional kinematics and kinetics were recorded from 45 healthy recreational runners during treadmill running at constant speed under various step rate conditions (preferred, ± 5%, and ± 10%). We tested our primary hypothesis that a reduction in energy absorption by the lower extremity joints during the loading response would occur, primarily at the knee, when step rate was increased.
less mechanical energy was absorbed at the knee (P < 0.01) during the +5% and +10% step rate conditions, whereas the hip (P < 0.01) absorbed less energy during the +10% condition only. All joints displayed substantially (P < 0.01) more energy absorption when preferred step rate was reduced by 10%. Step length (P < 0.01), center of mass vertical excursion (P < 0.01), braking impulse (P < 0.01), and peak knee flexion angle (P < 0.01) were observed to decrease with increasing step rate. When step rate was increased 10% above preferred, peak hip adduction angle (P < 0.01) and peak hip adduction (P < 0.01) and internal rotation (P < 0.01) moments were found to decrease.
we conclude that subtle increases in step rate can substantially reduce the loading to the hip and knee joints during running and may prove beneficial in the prevention and treatment of common running-related injuries.
... Appropriate proportions of those variables in the spatiotemporal structure optimize the dynamics of running, increasing its efficiency [7]. The parameters can also be important predictors of injury risk [11]. ...
... Conversely, an increased peak hip adduction angle may be one of the factors that causes patellofemoral pain [12]. In addition, it has been shown that an increased stride frequency can significantly reduce stress on the knee and hip joints, which can result in a lower risk of running injuries [11]. On the other hand, a literature review conducted by Brindle et al. [3] found no significant correlations between spatiotemporal parameters and injury history. ...
... Conversely, an increased peak hip adduction angle may be one of the factors that causes patellofemoral pain [12]. In addition, it has been shown that an increased stride frequency can significantly reduce stress on the knee and hip joints, which can result in a lower risk of running injuries [11]. On the other hand, a literature review conducted by Brindle et al. [3] has not found any significant correlations between spatiotemporal parameters and injury history. ...
Background:Running is one of the simplest and most popular forms of exercise. Biomechanical evaluation of running is one of the elements of evaluating running technique and, consequently, improving sports performance. Running uphill and downhill is one of the components of daily running but also an element of training used by recreational runners. The aim of this study is to optimize running training and minimize the risk of injury by identifying changes in the spatiotemporal structure of running at different inclinations. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. The protocol has been registered on the international platform INPLASY under the number INPLASY202430094U2. The search was conducted up to 30 March 2024 using the Scopus, PubMed, and Web of Science databases. Results: Spatiotemporal parameters were most frequently analyzed at 2.8–3.35 m/s velocities and inclinations in the range of −11% to 11%. Decreases in stride length (SL) and flight time (FT), and increases in step frequency (SF) were the most frequently reported changes from all parameters analyzed as a function of inclination and velocity. Significant increases or decreases in individual parameters were more often observed for positive inclination values than negative ones. Conclusions: The heterogeneous results of the study limit the possibility of determining the changes that occur in the spatiotemporal structure of the run under the impact of different inclinations. The variation in the results for negative inclination values indicates the different characteristics of running uphill and downhill. However, for uphill running, SF, SL, and FT are closely related to the increase in inclination.
... Increased cadence is interpreted as an increase in the step rate over a fixed distance and necessitates a proportional decrease in step length and increased step frequency when running at the same speed [15]. Research shows that increasing cadence can reduce running pain and improve knee function [16]. ...
... Research shows that increasing cadence can reduce running pain and improve knee function [16]. Improved biomechanics (i.e., reduced dynamic knee valgus and greater relative hip strength) along the kinetic chain have been observed with a cadence increase as low as 5% and, more consistently, as high as 10% [15,[17][18][19][20]. More importantly, a decrease in the peak forces required of the gluteal muscles has been observed with a 10% increase in running cadence due to a reduced abduction moment experienced at the hip [19]. ...
... It appears there is an inverse relationship between cadence and peak ground reaction forces, with reduced forces experienced along the kinetic chain [19,21]. Specifically, at the knee, participants experienced lower peak patellofemoral and tibiofemoral forces during increased cadences, along with reduced patellar tendon forces [15,19,22,23]. The clinical practice guidelines on patellofemoral pain state that increasing cadence may be used to reduce pain [2]. ...
Background: Patellofemoral pain is one of the most common injuries in recreational runners, with significant implications for dynamic knee valgus. The knee valgus angle can be corrected surgically or with a more conservative non-operative approach. Increasing running cadence may be an effective biomechanical gait retraining intervention to reduce knee valgus and thus patellofemoral pain. The primary purpose of this study was to examine if an increase in cadence could change the knee valgus angle. Methods: Ten asymptomatic recreational runners were recorded running on a treadmill during control and experimental intervals. Each interval lasted five minutes, and participants ran at 100% and 110% of their baseline cadence. Peak angles of knee valgus were compared between both intervals using the video analysis software application Dartfish Express. A paired sample, a two-tailed t-test, was used to determine the significant difference between bilateral frontal plane knee angle measurements during both intervals. Results: The average decrease in knee valgus measured in control versus experimental intervals was 2.23° for the right leg and 2.05° for the left leg, with a significance of p < 0.001 and p < 0.001, respectively. Conclusion: The results indicated a statistically significant decrease in angles of dynamic knee valgus, attributable to increased cadence. These changes in knee valgus angle are likely to have a positive impact on preventing and reducing pain associated with PFP.
... 9 Vertical loading rates (VLRs) and peak vertical ground reaction force are 2 metrics used to measure impact and have been previously linked to the development of running-related injuries. 14 Several running kinematic variables have been associated with VLR and vertical ground reaction force, including peak vertical tibial acceleration (VTA), 15 foot strike pattern, 16 cadence (steps per minute), 17 and vertical oscillation of the center of mass (VO). 18 The foot strike pattern is defined by the portion of the foot that contacts the running surface first at initial contact. ...
... Increases in cadence and decreases in VO are both associated with decreases in VLR and vertical ground reaction force. 17,18 The authors hypothesized that changes in running kinematics associated with reductions in VLR and vertical ground reaction force would manifest in decreased PFA. This study had 2 aims: (1) to examine the effect of foot strike pattern on PFA during running in healthy women and (2) to investigate the relationship between changes in PFA and changes in running kinematics as a result of manipulating foot strike pattern. ...
... Decreases in VO and increases in cadence have been previously associated with decreases in VLR and vertical ground reaction force. 17,18 During the right stance phase, changes in VTA and PFA showed a significant positive correlation for several time epochs during initial contact and loading response ( Table 5). VTA has been previously associated with VLR across all foot strike patterns. ...
Vertical loading rate (VLR) and pelvic floor muscle activity (PFA) increase with running velocity, which may indicate a relationship between VLR and PFA. Foot strike pattern has been shown to influence VLR while running, but little is known about its influence on PFA. Twenty healthy women ran on a treadmill for 2 conditions: with a rearfoot strike and with a forefoot strike. PFA was measured with electromyography. Running kinematics associated with VLR were collected using inertial measurement units and tibial accelerometers. Change scores between conditions were calculated for average PFA and running kinematics: peak vertical tibial acceleration, vertical excursion of the center of mass (VO), and cadence. Paired t tests assessed differences between running conditions for all variables. Pearson correlations assessed the relationships between changes in PFA and running kinematics. PFA was significantly higher during the forefoot compared with the rearfoot strike condition. Change in vertical tibial acceleration was positively correlated with change in PFA during the right stance. Change in cadence was negatively correlated, and change in vertical excursion of the center of mass was positively correlated with change in PFA during left stance. The average PFA increased during the forefoot strike pattern condition. Changes in PFA were correlated with changes in running kinematics associated with VLR.
... Los corredores recreacionales parecen estar ligeramente alejados de este punto óptimo (de Ruiter et al., 2013). Estudios previos han tratado de manipular la FZ entre un 5-10% sobre la FZ preferida (FZP), autoseleccionada por el corredor, para lograr una mejor economía de carrera (Amano et al., 2016;Heiderscheit et al., 2011). Sin embargo, estos estudios tienen la limitación de realizar los análisis en tapiz rodante a velocidad constante. ...
... Sin embargo, en los extremos de la curva con forma de "U" que relaciona las variables de zancada y la economía de carrera, ésta última disminuye cuando la variación en la FZ es igual o superior al 20% de la FZP (Cavanagh & Williams, 1982;Hunter & Smith, 2007). La mayoría de los estudios han analizado la FZ y/o la LZ durante la carrera a velocidades constantes (Heiderscheit et al., 2011;Hobara et al., 2012). Como alternativa, la tecnología portátil como relojes deportivos permiten trasladar la investigación del laboratorio a entornos de entrenamiento (Garcia et al., 2019;van Oeveren et al., 2019). ...
... Con respecto a la sección experimental, los corredores mostraron similares FZP (83 zancadas·min -1 ) que otros corredores a velocidades similares (de Ruiter et al., 2020;dos Santos et al., 2016;Lenhart et al., 2014). Desde una perspectiva general, los corredores podrían incrementar su FZP hasta cierto punto en el cual, el coste de carrera no incrementara significativamente (Mercer et al., 2008), pero con los beneficios biomecánicos que parecen ir asociados (dos Santos et al., 2016;Heiderscheit et al., 2011;Lenhart et al., 2014). Estos cambios positivos parecen estar asociados a menores lesiones relacionadas con la carrera (Cheung & Davis, 2011;Noehren et al., 2011). ...
This study aimed i) to study the agreement between a sports watch (Suunto Ambit2) with a photoelectric device (Optogait) as a reference instrument on measuring stride frequencies (SF) and stride lengths (SL); ii) to observe the stride patterns during outdoor running; and iii) to analyse the effect of SF manipulations on running economy monitored by a gas analyser and based on the observational analysis. One hundred and sixty recreational runners were analysed at speeds between 8-14 km·h-1. The Suunto Ambit2 agreed with the reference system [r=0.99 (0.99-1.00); Typical Error of the Estimate=0.58 strides•min-1 and 0.02m]. Runners tended to maintain SF constant [Coefficient of Variation (CV)=2.4%]) during variations in speed (CV=6.8%) while relied on SL (CV=6.5%) adjustments during outdoor running. Finally, runners seemed to maintain a low running cost with their auto-selected SF (average=81.3 strides•min-1), but an increase of up to 12% could be benefit when speed changes, without running cost detriment.
... For example, in our previous work, we investigated the stress-fracture risk for women of different statures while running with no load or a 22.7-kg load at a constant speed of 3.0 m/s, and found that, when compared to the no-load condition, the 22.7-kg load increased the tibial strain and stress-fracture risk among women of short and medium stature but not in tall women [14]. Several studies have shown that reducing stride length while maintaining a constant running speed induces changes to the joint kinematics [15,16] and decreases peak values of the joint kinetics [15,17,18], ground reaction force (GRF) [15], tibial strain, and tibial stress-fracture risk [19]. For instance, Heiderscheit et al. analyzed motion-capture data from healthy adult volunteers (men and women) who ran on a treadmill at their preferred speed for five different step rates (preferred, ± 5%, and ± 10%) and showed that a 10% increase above the preferred step rate at a constant speed decreases the energy absorbed at the knee and hip joints [15]. ...
... For example, in our previous work, we investigated the stress-fracture risk for women of different statures while running with no load or a 22.7-kg load at a constant speed of 3.0 m/s, and found that, when compared to the no-load condition, the 22.7-kg load increased the tibial strain and stress-fracture risk among women of short and medium stature but not in tall women [14]. Several studies have shown that reducing stride length while maintaining a constant running speed induces changes to the joint kinematics [15,16] and decreases peak values of the joint kinetics [15,17,18], ground reaction force (GRF) [15], tibial strain, and tibial stress-fracture risk [19]. For instance, Heiderscheit et al. analyzed motion-capture data from healthy adult volunteers (men and women) who ran on a treadmill at their preferred speed for five different step rates (preferred, ± 5%, and ± 10%) and showed that a 10% increase above the preferred step rate at a constant speed decreases the energy absorbed at the knee and hip joints [15]. ...
... For example, in our previous work, we investigated the stress-fracture risk for women of different statures while running with no load or a 22.7-kg load at a constant speed of 3.0 m/s, and found that, when compared to the no-load condition, the 22.7-kg load increased the tibial strain and stress-fracture risk among women of short and medium stature but not in tall women [14]. Several studies have shown that reducing stride length while maintaining a constant running speed induces changes to the joint kinematics [15,16] and decreases peak values of the joint kinetics [15,17,18], ground reaction force (GRF) [15], tibial strain, and tibial stress-fracture risk [19]. For instance, Heiderscheit et al. analyzed motion-capture data from healthy adult volunteers (men and women) who ran on a treadmill at their preferred speed for five different step rates (preferred, ± 5%, and ± 10%) and showed that a 10% increase above the preferred step rate at a constant speed decreases the energy absorbed at the knee and hip joints [15]. ...
Abstract Background Tibial stress fracture is a debilitating musculoskeletal injury that diminishes the physical performance of individuals who engage in high-volume running, including Service members during basic combat training (BCT) and recreational athletes. While several studies have shown that reducing stride length decreases musculoskeletal loads and the potential risk of tibial injury, we do not know whether stride-length reduction affects individuals of varying stature differently. Methods We investigated the effects of reducing the running stride length on the biomechanics of the lower extremity of young, healthy women of different statures. Using individualized musculoskeletal and finite-element models of women of short (N = 6), medium (N = 7), and tall (N = 7) statures, we computed the joint kinematics and kinetics at the lower extremity and tibial strain for each participant as they ran on a treadmill at 3.0 m/s with their preferred stride length and with a stride length reduced by 10%. Using a probabilistic model, we estimated the stress-fracture risk for running regimens representative of U.S. Army Soldiers during BCT and recreational athletes training for a marathon. Results When study participants reduced their stride length by 10%, the joint kinetics, kinematics, tibial strain, and stress-fracture risk were not significantly different among the three stature groups. Compared to the preferred stride length, a 10% reduction in stride length significantly decreased peak hip (p = 0.002) and knee (p
... Furthermore, there was a signi cant negative relationship between the values of the height and cadence of participants when ambulating with normal and Forward Head Postures but there was positive correlation between the former and step length. This implies that tallness have inverse relationship with cadence whereas height increases with step length [25,26] . There was a signi cant positive relationship between the step length and stride length of participants, either ambulating with or without Forward Head Postures. ...
... This also corroborated the observation of Landers [26] who reported that step length increases with the stride length. Ambulating with both normal and FHP showed that there was signi cant positive relationship between cadence and stride length as reported by Heiderscheit et al [25] . The limitations of this study are small sample size, absence of true control, narrow age range of participants and none utilization of a three-dimensional motion analysis system which is a modern scienti c method commonly employed for movement assessments in both clinical and research settings [2,27] CONCLUSION In conclusion, there were no signi cant differences in foot angle, stride length, cadence and walking speed when ambulating with normal and Forward Head Posture, excluding step length which was signi cant in the latter. ...
Background
Forward Head Posture (FHP) is an epidemic that has become more prevalent in recent times, with paucity of data on its effects on gait. This study aims to assess, compare and determine the relationship among age, anthropometric parameters and gait characteristics of ambulant with Normal and Forward Head Postures.
Methods
84 apparently healthy participants consented to participate in this pre-experimental study. Age, sex, weight and height of the participants were obtained. The participants were trained and instructed to walk a 8 meter walkway, with the floor sprinkled with white powder to obtain foot mark while maintaining two head postures (69° and 120° for normal and Forward Head Postures respectively). A rest interval of 30 minutes was observed before changing postures. Foot prints obtained from the powdered gait walkway were used to assess foot angle, cadence, stride length, step length and walking velocity. Data obtained were analyzed using descriptive and inferential statistics.
Results
The mean age of the participants was 21.92 ± 2.55years. Ambulation with normal head posture and forward head posture had mean values for foot angle (7.74 ± 2.02°, 7.58 ± 1.95°) cadence (107.83 ± 11.69cm, 111.02 ± 11.26cm) step length (65.45 ± 7.97cm, 68.68 ± 7.30cm) stride length (131.15 ± 17.11cm, 135.96 ± 15.12cm) and walking velocity (1.19 ± 0.32m/s, 1.13 ± 0.20m/s) respectively. There was significant difference in only the gait step length during ambulation with FHP (t = -2.74, p = 0.007). Cadence have significant relationships with age, height and step length (r = -0.28, p = 0.01; r = − .0.28, p = 0.01 and r = 0.43, 0.01). Step length have significant relationships only with weight and height (r = 0.34, p = 0.01 and r = 0.43, 0.01) while stride length had significant relationship only with height (r = 0.32, p = 0.01) in abnormal head posture. Similar trends were observed during ambulation with normal head posture.
Conclusions
Forward Head Posture (FHP) did not significantly alter most gait characteristics when compared to normal head posture. Cadence and step length have significant relationships with age, weight and height, irrespective of normal or abnormal posture. In FHP ambulation, Stride length had significant relationship only with height.
... Current researches reveal that cadence manipulation influences on both running mechanics and impacting forces. The components of running mechanics were improved including decreased heel strike, decreased braking impulse, decreased step length and decreased vertical excursion [13]. This also significantly reduces the impact forces when comparing a runner's preferred step rate to 5% or 10% slower than preferred. ...
... This increases the flow of nutrients and growth factors and promotes tissue healing and regeneration. [4] Hip abductor strengthening exercises plays a role in correcting the adduction torque of the lower extremity that improves the mobility of the band and reducing it friction with lateral femoral condyle iliotibial band syndrome [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Thus the group A athletes received gait retraining along with hip abductor strengthening exercises and ultrasound therapy in our study showed significant improvement than the Group B athletes received only hip abductor strengthening exercises and ultrasound therapy. ...
Iliotibial band syndrome (ITBS) is an inflammatory, non traumatic, knee overuse tendon injury of the iliotibial band in athletes. Friction in the band develops in the activities involving repetitive knee flexion. Gait retraining is vital in patients with iliotibial band syndrome in reducing its symptoms. Current researches reveal that cadence manipulation influences on both running mechanics and impacting forces. 30 athletes who fulfilled the predetermined selection criteria were selected and divided into two groups. Group A-Received gait retraining along with hip abductor strengthening and ultrasound therapy for thrice a week for 6 weeks. Group B-Received only hip abductor strengthening exercises and ultrasound therapy for thrice a week for 6 weeks. The pre test and post test data were analyzed using Paired and unpaired t test were used as statistical tools and the results showed the group A in which the athletes received gait retraining along with the hip abductor strengthening and ultrasound therapy showed significant improvement. Thus inclusion of gait retraining in the treatment protocol of iliotibial band syndrome will be effective in improving the performance of the athletes and early recovery.
... A total of 42 reflective markers were placed on the body segments of each athlete, of which 23 were located on anatomic landmarks. 17 A static standing posture, with 10 additional reflective markers placed, was recorded to identify joint centers and for model scaling. Marker positions were collected at 200 Hz using an 8-camera passive marker system (Motion Analysis Corp), while ground-reaction forces (GRFs) were synchronously collected at 2000 Hz. ...
... The knee joint kinetic variable of interest, peak knee extensor moment (PKEM), was calculated using biomechanical modeling and analyses as described previously. 17 Kinematic data and GRF data were low-pass filtered using a bidirectional, fourth-order Butterworth filter with a cutoff frequency of 12 Hz. A 14-segment articular linkage that was scaled to the athlete's height, mass, and segment length was utilized to model the body. ...
Background
Greater quadriceps strength symmetry is associated with better outcomes after anterior cruciate ligament reconstruction (ACLR). Isometric and isokinetic assessments of quadriceps strength inform therapeutic exercise prescription and return-to-sport decisions. It is unclear whether isometric and isokinetic measures provide similar information post-ACLR.
Hypothesis
Quadriceps strength symmetry is similar between isometric and isokinetic assessments. Isokinetic and isometric strength symmetries have similar associations to functional knee kinetics and self-reported knee function.
Study Design
Cross-sectional study.
Level of Evidence
Level 3.
Methods
NCAA Division I athletes (N = 35), 8.9 ± 2.5 months post-ACLR completed isometric and isokinetic quadriceps strength assessments, countermovement jumps (CMJs), and treadmill running. Self-reported knee function was assessed using the International Knee Documentation Committee Subjective Knee Form (IKDC). Agreement between isometric and isokinetic strength symmetry was assessed using Bland-Altman analysis, with associations to functional knee kinetics and IKDC assessed using Pearson correlations and linear regressions.
Results
Mean difference in quadriceps strength symmetry between isokinetic and isometric assessments was 1.0% (95% limits of agreement of -25.1% to 23.0%). Functional knee kinetics during running and CMJ were moderately to strongly associated with isometric strength symmetry ( r = 0.64-0.80, P < 0.01) and moderately associated with isokinetic strength symmetry ( r = 0.41-0.58, P < 0.01). IKDC scores were weakly to moderately associated with isometric ( r = 0.39, P = 0.02) and isokinetic ( r = 0.49, P < 0.01) strength symmetry.
Conclusion
Isokinetic and isometric assessments of quadriceps strength symmetry in collegiate athletes 9 months post-ACLR demonstrated strong agreement. Quadriceps strength symmetry is associated with functional knee kinetic symmetry post-ACLR.
Clinical Relevance
Considerable individual variation suggests mode of contraction should be consistent throughout postoperative assessment. Isometric strength symmetry may be a better indicator of functional knee kinetic symmetry, while isokinetic strength symmetry may be associated more closely with patient-reported outcomes.
... A significant group x time interaction was found for running pain (p = 0.010) and knee function (p = 0.019). Both programs had greater improvements in running pain compared to no intervention at T 24 gastrocnemius peak force, and ankle work) indicate that the demand was not shifted to these joints [19,20]. Gait retraining programs that increased cadence by 7.5-10% reduced pain levels post-training [13][14][15][16][17], and results were maintained six-months [17] after the protocol. ...
... Subjects were instructed to "run softer," "make their footfalls quieter" and to run without any beeps. Cadence group participants received guidance regarding their cadence and ran with the help of a metronome with an adjusted cadence increased by 7.5 to 10% [20,22,29] during the supervised and unsupervised sessions. In both groups, the unsupervised sessions were performed at a location of their choice, as long as it was overground running. ...
Background
Patellofemoral Pain (PFP) is one of the main injuries in runners. Consistent evidence support strengthening programs to modulate symptoms, however, few studies investigated the effects of gait retraining programs.
Objective
To investigate the effects of two different two-week partially supervised gait retraining programs on pain, function, and lower limb kinematics of runners with PFP.
Methods
Randomized controlled trial. Thirty runners were allocated to gait retraining groups focusing on impact (n = 10) or cadence (n = 10), or to a control group (n = 10). Impact group received guidance to reduce tibial acceleration by 50%, while cadence group was asked to increase cadence by 7.5–10%. The control group did not receive any intervention. Usual and running pain, knee function, and lower limb kinematics (contralateral pelvic drop, hip adduction, knee flexion, ankle dorsiflexion, tibia inclination, and foot inclination) were evaluated before (T0), immediately after the intervention (T2), and six months after the protocol (T24).
Results
A significant group x time interaction was found for running pain (p = 0.010) and knee function (p = 0.019). Both programs had greater improvements in running pain compared to no intervention at T24 (Impact x Control—mean difference (MD) −3.2, 95% CI −5.1 to −1.3, p = 0.001; Cadence x Control—MD −2.9, 95% CI −4.8 to −1.0, p = 0.002). Participants of the impact group had greater improvements in knee function compared to no intervention at T2 (Impact x Control–MD 10.8, 95% CI 1.0 to 20.6, p = 0.027). No between-group differences in usual pain and lower limb kinematics were found (p>0.05).
Conclusion
Compared to no intervention, both programs were more effective in improving running pain six months after the protocol. The program focused on impact was more effective in improving knee function immediately after the intervention.
Clinical trial registry number: RBR-8yb47v
... Previous studies have reported reduced knee range of motion with increases in stride rate (Anderson et al., 2022;Heiderscheit et al., 2011). Both Bounce ([Cluster 1]) and Stick ([Cluster 3]) runners showed higher stride cadence compared to Push runners ([Cluster 2]), although only Stick runners ([Cluster 3]) showed differences in joint kinematics during the stance. ...
... This suggests that a change in knee kinematics requires that stride cadence and Duty Factor increase at same time. This concurs with the results reported by Heiderscheit et al. (2011), who observed a decrease in peak knee flexion with increases in stride cadence greater than 10% along with increases in Duty Factor. By contrast, Patoz et al. (2020). ...
The purpose of this study was to analyse the differences in joint kinematic patterns among runners with different spatiotemporal characteristics in the running cycle. Lower extremity kinematic data and spatiotemporal stride parameters were collected for ninety-two recreational runners during a treadmill run at a self-selected comfortable speed. A K-means clustering analysis was conducted on normalised stride cadence and Duty Factor to identify running style. Cluster 1 characterised by reduced stance times and low Duty Factor; Cluster 2, long stance times and low stride cadence; Cluster 3, high Duty Factor and stride cadence. Functional principal component analysis was used to identify patterns of variability between runners. Runners who used a combination of high cadence and Duty Factor showed differences in hip, knee and ankle sagittal kinematics compared to other runners. On the contrary, the joint kinematics was not altered when the Duty Factor was increased along with a decrease in the stride cadence. This study has demonstrated that the combination of several spatial-temporal parameters of the running cycle should be considered when analysing the movement pattern of the lower limb.
... This allowance was made to enhance participant autonomy and compliance without compromising performance; in addition, beneficial changes have been found with a change as little as 5% increase in cadence. 8 Once the participant reported comfort with a cadence between 5-10% above their average for one lap they were done with the session. They were asked to run or complete a combination of running and walking at least three times for 30 minutes for two weeks, running at their new increased self-selected cadence. ...
... Heiderscheit et al. and Schubert et al. report the minimum change in step frequency required to observe biomechanical change is a 10% increase in cadence, although some changes are seen with a 5% increase. 8,14 Therefore, the low percentage of overall change in cadence along with in field data measuring error may have limited the detection of changes in biomechanical variables. ...
Background
Running is a common leisure physical activity that carries a risk for running related injury (RRI). Non-experienced runners are more likely to sustain RRIs. One form of gait retraining focuses on increasing cadence to improve running biomechanics related to RRI. Protocols for increasing cadence must be pragmatic to be implemented into clinical practice.
Hypothesis/Purpose
The purpose of this study was to determine if a pragmatic protocol including one instructional session, followed by independent gait retraining with metronome augmentation resulted in increased cadence and altered biomechanics in novice and recreational runners.
Study Design
Randomized Controlled Trial
Methods
Thirty-three novice or recreational adult runners completed a 12 Minute Cooper Run on an indoor track. Variables measured during the 12 Minute Cooper Run included distance, rate of perceived exertion (RPE), heart rate (HR), and 3-D biomechanics using inertial measurement units (IMUs). After baseline testing, the intervention group received instruction and five minutes of gait retraining at a cadence set 5-10% higher than baseline with metronome augmentation (Pro Metronome- Tempo, Beat; by Xiao Yixiang). They then ran two to three times a week for two weeks up to 30 minutes per session with the metronome set at the new cadence. After two weeks, repeat testing using the same protocol was completed. A Mann-Whitney U test analyzed differences between groups.
Results
Cadence at one minute (p = 0.037) and average cadence over the entire run (p=0.002) increased in the intervention group only with a large effect size (Cohens d = 0.837). No other group differences were found.
Conclusion
A pragmatic gait retraining protocol with metronome augmentation including one instructional and four to six independent sessions over a two-week duration increased cadence without negative effects on HR, RPE, distance. Biomechanics did not change with this intervention. Further research with pragmatic gait retraining protocols that increase cadence are needed with larger sample sizes, repeated measures over time, across runners of various abilities and experience levels.
Level of Evidence
Level 2
... External pacing strategies that target improvements in cadence are implemented in both clinical and training settings for runners. From a clinical standpoint, providing a faster cadence is a relevant alternative as it reduces lower extremity joint loading and forces, as compared to a self-selected cadence at equivalent running speed (Hafer et al., 2014;Heiderscheit et al., 2011;Hobara et al., 2012;Lenhart et al., 2014;Lyght et al., 2016;Schubert et al., 2014). Thus, increasing cadence is a viable strategy to reduce the risk of running-related injury and pain (Barton et al., 2016;Hafer et al., 2014;Heiderscheit et al., 2011;Hobara et al., 2012;Lenhart et al., 2014;Lyght et al., 2016;Schubert et al., 2014). ...
... From a clinical standpoint, providing a faster cadence is a relevant alternative as it reduces lower extremity joint loading and forces, as compared to a self-selected cadence at equivalent running speed (Hafer et al., 2014;Heiderscheit et al., 2011;Hobara et al., 2012;Lenhart et al., 2014;Lyght et al., 2016;Schubert et al., 2014). Thus, increasing cadence is a viable strategy to reduce the risk of running-related injury and pain (Barton et al., 2016;Hafer et al., 2014;Heiderscheit et al., 2011;Hobara et al., 2012;Lenhart et al., 2014;Lyght et al., 2016;Schubert et al., 2014). For training, external pacing strategies are often implemented to help beginners respond better to changes in pace during racing, and maintain cadence during fatigue (Aranki et al., 2018;Fortmann et al., 2012). ...
... A common instruction method for modifying cadence is acoustic pacing. A metronome beat or music specifying the desired cadence is played, and the runner synchronizes their steps to the corresponding rhythm [11][12][13]. Acoustic pacing for cadence modulation was proven to be effective for running on a treadmill in the laboratory [11,12]. An important difference between treadmill running and overground running is that changes in speed are restricted in treadmill running but not in overground running. ...
... A metronome beat or music specifying the desired cadence is played, and the runner synchronizes their steps to the corresponding rhythm [11][12][13]. Acoustic pacing for cadence modulation was proven to be effective for running on a treadmill in the laboratory [11,12]. An important difference between treadmill running and overground running is that changes in speed are restricted in treadmill running but not in overground running. ...
According to the dual-axis model, running styles can be defined by cadence and duty factor, variables that have been associated with running performance, economy and injury risk. To guide runners in exploring different running styles, effective instructions to modulate cadence and duty factor are needed. Such instructions have been established for treadmill running, but not for overground running, during which speed can be varied. In this study, five participants completed eight field training sessions over a 4-week training period with acoustic instructions to modulate cadence, duty factor, and, in combination, running style. Instructions were provided via audio files. Running data were collected with sports watches. Participants’ experiences with guided-exploration training were evaluated with the user experience questionnaire. Data analysis revealed acoustic pacing and verbal instructions to be effective in respectively modulating cadence and duty factor, albeit with co-varying effects on speed and the non-targeted variable (i.e. duty factor or cadence). Combining acoustic pacing and verbal instructions mitigated these co-varying effects considerably, allowing for running-style modulations in intended directions (particularly towards the styles with increased cadence and increased duty factor). User experience of this form of guided-exploration training was overall positive, but could be improved in terms of autonomy (dependability). In conclusion, combining acoustic pacing and verbal instructions for running-style modulation is effective in overground running.
... In total, 52 reflective markers (23 on anatomic landmarks) were placed on each athlete. 17 To identify hip joint centers and for model scaling, a static standing posture was recorded. Kinematics were sampled at 200 Hz using an 8-camera system (Motion Analysis Corporation) and recorded synchronously with GRFs, which were sampled at 2000 Hz. ...
... Inverse kinematic and dynamic routines were performed as previously described. 17 GRF and kinematic data were low-pass filtered using a bidirectional, fourthorder Butterworth filter with a cutoff frequency of 12 Hz. A generic 14-segment, 31 degrees of freedom articular linkage, scaled to the athlete's height, mass, and segment lengths, was used to model the body. ...
Background:
After anterior cruciate ligament reconstruction (ACLR), altered surgical knee biomechanics during running is common. Although greater quadriceps strength is associated with more symmetrical running knee kinetics after ACLR, abnormal running mechanics persist even after resolution of quadriceps strength deficits. As running is a submaximal effort task characterized by limited time to develop knee extensor torque, quadriceps rate of torque development (RTD) may be more closely associated with recovery of running knee mechanics than peak torque (PT).
Purpose:
To assess the influence of recovery in quadriceps PT and RTD symmetry on knee kinematic and kinetic symmetry during running over the initial 2 years after ACLR.
Study design:
Cohort study; Level of evidence, 3.
Methods:
A total of 39 Division I collegiate athletes (106 testing sessions; 19 female) completed serial isometric performance testing and running analyses between 3 and 24 months after ACLR. Athletes performed maximal and rapid isometric knee extension efforts with each limb to assess PT and RTD between-limb symmetry indices (PTLSI and RTDLSI), respectively. Peak knee flexion difference (PKFDIFF) and peak knee extensor moment limb symmetry index (PKEMLSI) during running were computed. Multivariable linear mixed-effects models assessed the influence of PTLSI and RTDLSI on PKFDIFF and PKEMLSI over the initial 2 years after ACLR.
Results:
Significant main effects of RTDLSI (P < .001) and time (P≤ .02) but not PTLSI (P≥ .24) were observed for both PKFDIFF and PKEMLSI models. For a 10% increase in RTDLSI, while controlling for PTLSI and time, a 0.9° (95% CI, 0.5°-1.3°) reduction in PKFDIFF and a 3.5% (95% CI, 1.9%-5.1%) increase in PKEMLSI are expected. For every month after ACLR, a 0.2° (95% CI, 0.1°-0.4°) reduction in PKFDIFF and a 1.3% (95% CI, 0.6%-2.0%) increase in PKEMLSI are expected, controlling for PTLSI and RTDLSI.
Conclusion:
Quadriceps RTDLSI was more strongly associated with symmetrical knee biomechanics during running compared with PTLSI or time throughout the first 2 years after ACLR.
... In comparison to moderate-intensity running, a reduction in hip joint angle at initial contact at heavy and severe exertions (0.5 and 1.2%, respectively) and a reduction in hip joint angle at toe-off at severe intensity (0.9%) were detected, reflecting a greater hip flexion [27]. Also, a reduction in knee joint angle at initial contact was observed at heavy and severe domains (0.5 and 1.5%, respectively), indicating a greater knee flexion [28] without an increase in its extension at toe-off. The lack of change in ankle joint angle with the velocity rise has already been reported [3] and may be attributed to the constant stride frequency, particularly at higher intensities, as well as the submaximal velocity attained (since muscular changes have been described at faster running) [22]. ...
Runners achieve forward locomotion through diverse techniques. However, understanding the behavior of the involved kinematical variables remains incomplete, particularly when running overground and along an intensity spectrum. We aimed to characterize the biomechanical and physiological adaptations while running at low, moderate, heavy and severe intensities. Ten middle- and long-distance runners completed an incremental intermittent protocol of 800 m steps until exhaustion (1 km·h−1 velocity increments and 30 s intervals) on an outdoor track field. Biomechanical data were captured using two high-resolution video cameras, and linear and angular kinematic variables were analyzed. With the intensity rise, a decrease in stride, step and contact times ([0.70–0.65], [0.35–0.33] and [0.42–0.37] s) and an increase in stride length and frequency and flight time ([3.13–3.52] m, [1.43–1.52] Hz and [0.28–0.29] s; p < 0.05) were observed, together with an increase in oxygen uptake and blood lactate concentrations ([54.7–67.6] mL∙kg−1∙min−1 and [3.1–10.2] mmol∙L−1). A more flexed hip at initial contact and toe-off (152.02–149.36] and [165.70–163.64]) and knee at initial contact ([162.64–159.57]; p < 0.05) were also observed. A consistent gait pattern along each protocol step was exhibited, with minor changes without practical significance. Runners are constantly adapting their gait pattern, reflected in both biomechanical and physiological responses, both of which should be considered for better characterization.
... At the mid-swing stage (70-80% of a gait cycle), increased calf muscle activity may play a key role in promoting landing position change, reducing knee joint torque and energy absorption (Heiderscheit et al., 2011). This experiment shows that the RMS amplitude of GM and GL in the forefoot striking group is higher than in the rearfoot striking group, suggesting that increased gastrocnemius muscle activity in the forefoot striking group reduces knee joint torque, aiding landing position adjustment in running. ...
... Current evidence demonstrates that gait retraining in healthy runners reduces AVLR and may reduce RRIs (Chan et al., 2018;Fisher et al., 2024). Additionally, healthy runners who increase their step rate by 10 % demonstrate decreased peak hip adduction angles (Heiderscheit et al., 2011). In injured runners with knee pain, gait retraining that includes a transition from a RFS to a NRFS pattern has been shown to improve function, pain, and biomechanical risk factors related to RRI (Dos Santos et al., 2019;Mazzone et al., 2022;Roper et al., 2016). ...
... A reduction in stride speed may be attributed to a decline in either stride frequency or stride length. A diminution in stride frequency may result in an extended single-support phase during ambulation, a prolonged loading period at the knee, and ultimately, an augmented loading of the knee, which may elevate the risk of recurrent patellofemoral joint discomfort (Heiderscheit et al., 2011;Van Hooren et al., 2024). Martín-Martínez et al. (2020) examined the impact of cognitive perturbation on the gait pattern of female individuals. ...
Purpose
This study aimed to analyze the biomechanical characteristics of the lower limb in patients with patellofemoral pain (PFP) while walking under different sensory integration tasks and elucidate the relationship between these biomechanical characteristics and patellofemoral joint stress (PFJS). Our study’s findings may provide insights which could help to establish new approaches to treat and prevent PFP.
Method
Overall, 28 male university students presenting with PFP were enrolled in this study. The kinematic and kinetic data of the participants during walking were collected. The effects of different sensory integration tasks including baseline (BL), Tactile integration task (TIT), listening integration task (LIT), visual integration task (VIT) on the biomechanical characteristics of the lower limb were examined using a One-way repeated measures ANOVA. The relationship between the aforementioned biomechanical characteristics and PFJS was investigated using Pearson correlation analysis.
Results
The increased hip flexion angle (P = 0.016), increased knee extension moment (P = 0.047), decreased step length (P < 0.001), decreased knee flexion angle (P = 0.010), and decreased cadence (P < 0.001) exhibited by patients with PFP while performing a VIT were associated with increased patellofemoral joint stress. The reduced cadence (P < 0.050) achieved by patients with PFP when performing LIT were associated with increased patellofemoral joint stress.
Conclusion
VIT significantly influenced lower limb movement patterns during walking in patients with PFP. Specifically, the increased hip flexion angle, increased knee extension moment, decreased knee flexion angle, and decreased cadence resulting from this task may have increased PFJS and may have contributed to the recurrence of PFP. Similarly, patients with PFP often demonstrate a reduction in cadence when exposed to TIT and LIT. This may be the main trigger for increased PFJS under TIT and LIT.
... At 60 beats/min this would indicate a deviation of a maximum of 6 steps/min, whereas at 120 beats/min this would indicate a deviation of a maximum of 12 steps/min. Based on the literature, step rates can be altered up to ± 10% from the preferred running SR (Heiderscheit et al., 2011;Kiernan et al., 2024) without harmful effects, such that the 10% threshold seems an appropriate choice. ...
Introduction
One way to improve exercise performance and protect heart health is the extended synchronization of the stepping with the diastolic phase of the cardiac cycle. Cardiac-locomotor coupling (CLC) happens when the step rate (SR) equals the heart rate (HR). The extent of CLC in daily life is unknown. This study aims to analyze spontaneous occurrences of CLC during daily activities.
Methods
A retrospective analysis of daily life recordings from a wrist-worn sensor was undertaken (PMData, N = 16, 5 months duration). The deviation between HR and SR was used to define CLC (deviation ≤ 1%) and weak CLC (1%< deviation ≤ 10%). The occurrence and the probability of CLC during everyday life were computed from the recordings. The CLC occurrences were stratified depending on the duration and intensity of the physical activity. Finally, a Monte Carlo simulation was run to evaluate the probability of random occurrences of CLC vs. the observed recordings.
Results
Participants couple for 5% and weakly couple for 35% of the observational period. The ratio of 1:1 between HR and SR is the dominating occurrence across the study population and this overrepresentation is significant. CLC occurs mostly for long activities. The extent of CLC for various intensities of activity is subject-dependent. The results suggest that CLC is feasible for most people.
Conclusions
CLC occurs spontaneously during unsupervised daily activity in everyone in our cohort, which suggests a mechanistic interaction between the cardiac and the locomotor systems. This interaction should be investigated for medical rehabilitation and sports applications in the future.
... The measurement of mechanical work (figure 2) was in good agreement with previous literature reporting W com and W int [3,34] and lower-limb joint work [35,36] during running at different step frequencies. The estimate of the substantial soft tissue network suggests that 'traditional' methods (figures 1 and 3) may either over-or under-estimate the muscular work performed by the body during running. ...
This study aims to investigate the relationship between soft tissue energy dissipation and leg stiffness during running. Eight recreational healthy male runners (age: 22.2 ± 1.0 years; height: 1.84 ± 0.03 m; mass: 73.7 ± 5.7 kg) were asked to run at different speeds and step frequencies. Their soft tissue energy dissipation was estimated by the difference between the total mechanical work of the body, measured as the work done to move the body centre of mass relative to the surroundings plus the work to move the limbs relative to the body centre of mass, and lower-limb joint work. A mass-spring model with an actuator was used to analyse the force–length curve of the bouncing mechanism of running. In this way, the stiffness and damping coefficient were assessed at each speed and step frequency. Pearson's correlations were used to describe the relationship between the deviation from the spring-mass model and soft tissue energy fluctuations. The soft tissue dissipation was found to be significantly influenced by step frequency, with both positive and negative work phases decreasing when step frequency increases. Moreover, deviation from a spring-mass model was positively associated with the amount of soft tissue dissipation (r > 0.6). The findings emphasize the substantial role of soft tissues in dissipating or returning energy during running, behaving in a damped-elastic manner. Also, we introduce a novel approach for evaluating the elastic rebound of the body during running. The insights gained may have broad implications for assessing running mechanics, with potential applications in various contexts.
... The order of these conditions was also randomized. These latter conditions were included to assess the validity of the predicted tissue loads during common gait-retraining methods (e.g., [32,33]). This may in turn inform on the suitability of the wearable to quantify the effectiveness of gait retraining at modifying tissue loading. ...
Introduction
Wearables have the potential to provide accurate estimates of tissue loads at common running injury locations. Here we investigate the accuracy by which commercially available instrumented insoles (ARION) can predict musculoskeletal loading at common running injury locations.
Methods
19 runners (10 males) ran at five different speeds, four slopes, with different step frequencies, and forward trunk lean on an instrumented treadmill, while wearing instrumented insoles. The insole data was used as input to an artificial neural network that was trained to predict the Achilles tendon strain, and tibia and patellofemoral stress impulses and weighted impulses (damage proxy) determined with musculoskeletal modelling. Accuracy was investigated using leave-one-out cross-validation and correlations. The effect of different input metrics was also assessed.
Results
The neural network predicted tissue loading with overall relative percentage errors of 1.95 ± 8.40, -7.37 ± 6.41, and -12.8 ± 9.44% for the patellofemoral joint, tibia and Achilles tendon impulse, respectively. The accuracy significantly changed with altered running speed, slope, or step frequency. Mean (95% confidence interval) within-individual correlations between modelled and predicted impulses across conditions were generally nearly perfect, being 0.92 (0.89 to 0.94); 0.95 (0.93 to 0.96); and 0.95 (0.94 to 0.96) for the patellofemoral, tibial, and Achilles tendon stress/strain impulses, respectively.
Conclusions
This study shows that commercially available instrumented insoles can predict loading at common running injury locations with variable absolute, but (very) high relative accuracy. The absolute error was lower than methods that measure step-count only, or assume a constant load per speed or slope. This developed model may allow for quantification of in-field tissue loading and real-time tissue loading-based feedback to reduce injury risk.
... The existing body of research consistently demonstrates that increasing cadence within the range of 5% to 30% from the habitual cadence can confer protective mechanical benefits against injury. Several studies collectively support the notion that cadence modification is a valuable approach for mitigating the risk of musculoskeletal injuries during physical activity [53][54][55]. There was no significant interaction found between years as a recreation runner and running speed (p = 0.07). ...
Background:
Despite the numerous health benefits of distance running, it is also associated with the development of 'gradual onset running-related injuries' (GORRIs) one of which is Iliotibial Band Syndrome (ITBS). Novel risk factors associated with a history of ITBS (hITBS) have not been described in a large cohort of distance runners.
Objective:
To identify risk factors associated with hITBS in distance runners.
Design:
Descriptive cross-sectional study.
Setting:
21.1 km and 56 km Two Oceans Marathon races (2012-2015).
Participants:
106 743 race entrants completed the online pre-race medical screening questionnaire. A total of 1 314 runners confirmed an accurate hITBS diagnosis.
Methods:
Selected risk factors associated with hITBS explored included: demographics (race distance, sex, age groups), training/running variables, history of existing chronic diseases (including a composite chronic disease score) and history of any allergy. Prevalence (%) and prevalence ratios (PR; 95% CI) are reported (uni- & multiple regression analyzes).
Results:
1.63% entrants reported hITBS in a 12-month period. There was a higher (p < 0.0001) prevalence of hITBS in the longer race distance entrants (56 km), females, younger entrants, fewer years of recreational running (PR = 1.07; p = 0.0009) and faster average running speed (PR = 1.02; p = 0.0066). When adjusted for race distance, sex, age groups, a higher chronic disease composite score (PR = 2.38 times increased risk for every two additional chronic diseases; p < 0.0001) and a history of allergies (PR = 1.9; p < 0.0001) were independent risk factors associated with hITBS.
Conclusion:
Apart from female sex, younger age, fewer years of running and slower running speed, two novel independent risk factors associated with hITBS in distance runners are an increased number of chronic diseases and a history of allergies. Identifying athletes at higher risk for ITBS can guide healthcare professionals in their prevention and rehabilitation efforts.
... Transitioning from a rearfoot to a fore-foot landing position has been shown to reduce GRF impact magnitude and rate 16 and has been postulated to reduce injury rate 3 , but conflicting evidence exists 17 . Additionally, fore-foot strikers can still land with a more extended leg position at foot contact, similar to rear-foot strikers, increasing the stiffness of the leg as well as the braking force required to decelerate the body 14 . ...
Running injuries are prevalent, but their exact mechanisms remain unknown largely due to limited real-world biomechanical analysis. Reducing overstriding, the horizontal distance that the foot lands ahead of the body, may be relevant to reducing injury risk. Here, we leverage the geometric relationship between overstriding and lower extremity sagittal segment angles to demonstrate that wearable inertial measurement units (IMUs) can predict overstriding during treadmill and overground running in the laboratory. Ten recreational runners matched their strides to a metronome to systematically vary overstriding during constant-speed treadmill running and showed similar overstriding variation during comfortable-speed overground running. Linear mixed models were used to analyze repeated measures of overstriding and sagittal segment angles measured with motion capture and IMUs. Sagittal segment angles measured with IMUs explained 95% and 98% of the variance in overstriding during treadmill and overground running, respectively. We also found that sagittal segment angles measured with IMUs correlated with peak braking force and explained 88% and 80% of the variance during treadmill and overground running, respectively. This study highlights the potential for IMUs to provide insights into landing and loading patterns over time in real-world running environments, and motivates future research on feedback to modify form and prevent injury.
... In this context, small alterations in the repetitive motions associated with running can exert an extensive effect on the stress on lower extremity joints. For instance, increasing step rate can influence the force at the foot-ground interface, as well as at the joints in the lower extremity kinetic chain [4], [6], [7], [8], [9]. Accordingly, analysis of running gait is of considerable interest. ...
A novel, wearable, stretchable Smart Patch can monitor various aspects of physical activity, including the dynamics of running. However, like any new device developed for such applications, it must first be tested for validity and reliability. Here, we compare the step rate while running on a treadmill measured by this smart patch with the corresponding values obtained with the ”gold standard” OptoGait, as well as with other devices commonly used to assess running dynamics, i.e., the MEMS accelerometer and commercially available and widely used Garmin Running Dynamic Pod. The 14 healthy, physically active volunteers completed two identical sessions with a 5-minute rest between. Each session involved two one-minute runs at 11 km/h and 14 km/h separated by a one-min rest. The major finding was that the Smart Patch demonstrated fair to good test-retest reliability. The best test-retest reliability for the Running Pod was observed in connection with running at 11 km/h and both velocities combined (good and excellent, respectively) and for the OptoGait when running at 14 km/h (good). The best concurrent validity was achieved with the Smart Patch, as reflected in the highest Pearson correlation coefficient for this device when running at 11 or 14 km/h, as well as for both velocities combined. In conclusion, this study demonstrates that the novel wearable Smart Patch shows promising reliability and excellent concurrent validity in measuring step rate during treadmill running, making it a viable tool for both research and practical applications in sports and exercise science.
... Several studies have proposed changes to running techniques (i.e., movement) through running retraining using feedback to reduce impact loads [36]. A study found that increasing step cadence by just 5% significantly reduced peak braking force by 5.7% [37] and 11.4% [38] in long-distance runners. Increasing step cadence with a proportional reduction in the stride length at a constant speed has reduced foot inclination angles and impact forces by 5.6% [39] which decreases the number of initial contacts by hindfoot [40]. ...
Foot pronation is a prevalent condition known to contribute to a range of lower extremity injuries. Numerous interventions have been employed to address this issue, many of which are expensive and necessitate specific facilities. Gait retraining has been suggested as a promising intervention for modifying foot pronation, offering the advantage of being accessible and independent of additional materials or specific time. We aimed to systematically review the literature on the effect of gait retraining on foot pronation. We searched four databases including PubMed, Web of Science, Scopus and Embase from their inception through 20 June 2023. The Downs and Black appraisal scale was applied to assess quality of included studies. Two reviewers screened studies to identify studies reporting the effect of different methods of gait-retraining on foot pronation. Outcomes of interest were rearfoot eversion, foot pronation, and foot arch. Two authors separately extracted data from included studies. Data of interest were study design, intervention, variable, sample size and sex, tools, age, height, weight, body mass index, running experience, and weekly distance of running. Mean differences and 95% confidence intervals (CI) were calculated with random effects model in RevMan version 5.4. Fifteen studies with a total of 295 participants were included. The results of the meta-analysis showed that changing step width does not have a significant effect on peak rearfoot eversion. The results of the meta-analysis showed that changing step width does not have a significant effect on peak rearfoot eversion. Results of single studies indicated that reducing foot progression angle (MD 2.1, 95% CI 0.62, 3.58), lateralizing COP (MD -3.3, 95% CI -4.88, -1.72) can effectively reduce foot pronation. Overall, this study suggests that gait retraining may be a promising intervention for reducing foot pronation; Most of the included studies demonstrated significant improvements in foot pronation following gait retraining. Changing center of pressure, foot progression angle and forefoot strike training appeared to yield more favorable outcomes. However, further research is needed to fully understand its effectiveness and long-term benefits.
... Inverse kinematic and dynamic routines were performed as previously described (23). A 14-segment, 31 degree-of-freedom articular linkage, scaled to the athlete's height, mass, and segment lengths, was used to model the body using SIMM Motion Module (Motion Analysis Corporation) (24). ...
Introduction
Athletes post-anterior cruciate ligament reconstruction (ACLR) demonstrate altered surgical knee running kinematics and kinetics compared to the non-surgical limb and healthy controls. The effect of running speed on biomechanics has not been formally assessed in athletes post-ACLR. The purpose of this study was to characterize how knee biomechanics change with running speed between 3.5-7 (EARLY) and 8-13 (LATE) months post-ACLR.
Methods
Fifty-five Division I collegiate athletes post-ACLR completed running analyses (EARLY: n = 40, LATE: n = 41, both: n = 26) at 2.68, 2.95, 3.35, 3.80 and 4.47 m/s. Linear mixed effects models assessed the influence of limb, speed, time post-ACLR, and their interactions on knee kinematics and kinetics.
Results
A significant limb*speed interaction was detected for peak knee flexion, knee flexion excursion, and rate of knee extensor moment (p-values <0.02), controlling for time. From 3.35 to 4.47 m/s knee flexion excursion decreased -2.3° (95% CI: -3.6, -1.0) in the non-surgical limb and -1.0° (95% CI: -2.3, -0.3) in the surgical limb. Peak vertical ground reaction force, peak knee extensor moment, and knee negative work increased similarly with speed for both limbs (p-values <0.002). A significant limb*time interaction was detected for all variables (p-values <0.001). Accounting for running speed, improvements in all surgical limb biomechanics were observed from EARLY to LATE (p-values <0.001), except for knee flexion at initial contact (p = 0.12), but between-limb differences remained (p-values <0.001).
Conclusions
Surgical and non-surgical knee biomechanics increase similarly with speed in collegiate athletes at EARLY and LATE, with the exception of peak knee flexion, knee flexion excursion, and rate of knee extensor moment. Surgical knee biomechanics improved from EARLY and LATE, but significant between-limb differences persisted.
... A target of ±10 steps min −1 (corresponding to 6% of the preferred frequency at the same speed) was used as this has been shown to be sufficient to alter running biomechanics associated with injury risk. 36 Step frequency was manipulated using a metronome and participants were instructed to synchronize their step frequency with the beat frequency of the metronome. The order of the step frequency conditions was also randomized. ...
Understanding how loading and damage on common running injury locations changes across speeds, surface gradients, and step frequencies may inform training programs and help guide progression/rehabilitation after injuries. However, research investigating tissue loading and damage in running is limited and fragmented across different studies, thereby impairing comparison between conditions and injury locations. This study examined per‐step peak load and impulse, cumulative impulse, and cumulative weighted impulse (hereafter referred to as cumulative damage) on three common injury locations (patellofemoral joint, tibia, and Achilles tendon) across different speeds, surface gradients, and cadences. We also explored how cumulative damage in the different tissues changed across conditions relative to each other. Nineteen runners ran at five speeds (2.78, 3.0, 3.33, 4.0, 5.0 m s⁻¹), and four gradients (−6, −3, +3, +6°), and three cadences (preferred, ±10 steps min⁻¹) each at one speed. Patellofemoral, tibial, and Achilles tendon loading and damage were estimated from kinematic and kinetic data and compared between conditions using a linear mixed model. Increases in running speed increased patellofemoral cumulative damage, with nonsignificant increases for the tibia and Achilles tendon. Increases in cadence reduced damage to all tissues. Uphill running increased tibial and Achilles tendon, but decreased patellofemoral damage, while downhill running showed the reverse pattern. Per‐step and cumulative loading, and cumulative loading and cumulative damage indices diverged across conditions. Moreover, changes in running speed, surface gradient, and step frequency lead to disproportional changes in relative cumulative damage on different structures. Methodological and practical implications for researchers and practitioners are discussed.
... Where running step rate varied, foot inclination angles [20], time in stance phase [18] and foot-strike patterns [19] also differed significantly between sub-groups. Given the established relationship between these variables [53][54][55][56], there is a compelling argument for the role of step rate in kinematic sub-group differentiation. ...
Background
Historically, kinematic measures have been compared across injured and non-injured groups of runners, failing to take into account variability in kinematic patterns that exist independent of injury, and resulting in false positives. Research led by gait patterns and not pre-defined injury status is called for, to better understand running-related injury (RRI) aetiology and within- and between-group variability.
Objectives
Synthesise evidence for the existence of distinct kinematic sub-groups across a population of injured and healthy runners and assess between-group variability in kinematics, demographics and injury incidence.
Data Sources
Electronic database search: PubMed, Web of Science, Cochrane Central Register of Controlled Trials (Wiley), Embase, OVID, Scopus.
Eligibility Criteria
Original, peer-reviewed, research articles, published from database start to August 2022 and limited to English language were searched for quantitative and mixed-methods full-text studies that clustered injured runners according to kinematic variables.
Results
Five studies (n = 690) were included in the review. All studies detected the presence of distinct kinematic sub-groups of runners through cluster analysis. Sub-groups were defined by multiple differences in hip, knee and foot kinematics. Sex, step rate and running speed also varied significantly between groups. Random injury dispersal across sub-groups suggests no strong evidence for an association between kinematic sub-groups and injury type or location.
Conclusion
Sub-groups containing homogeneous gait patterns exist across healthy and injured populations of runners. It is likely that a single injury may be represented by multiple movement patterns, and therefore kinematics may not predict injury risk. Research to better understand the underlying causes of kinematic variability, and their associations with RRI, is warranted.
... First, knee (and specifically patellofemoral) injuries are the most common injuries among novice runners. 25 Because several studies have found patellofemoral loading to decrease with increases in step frequencies, 26,27 we anticipate that the wearable will also aim to increase step frequency to reduce patellofemoral loading. Second, studies that have investigated running economy across different step frequencies indicate that novice runners often select a step frequency that is slightly lower than their theoretical most economical step frequency, 21 and we therefore expect the wearable to increase step frequency for most runners. ...
Background
An increasing number of commercially available wearables provide real‐time feedback on running biomechanics with the aim to reduce injury risk or improve performance.
Objective
Investigate whether real‐time feedback by wearable insoles (ARION) alters running biomechanics and improves running economy more as compared to unsupervised running training. We also explored the correlation between changes in running biomechanics and running economy.
Methods
Forty recreational runners were randomized to an intervention and control group and performed ~6 months of in‐field training with or without wearable‐based real‐time feedback on running technique and speed. Running economy and running biomechanics were measured in lab conditions without feedback pre and post intervention at four speeds.
Results
Twenty‐two individuals (13 control, 9 intervention) completed both tests. Both groups significantly reduced their energetic cost by an average of −6.1% and −7.7% for the control and intervention groups, respectively. The reduction in energy cost did not significantly differ between groups overall (−0.07 ± 0.14 J∙kg∙m⁻¹, −1.5%, p = 0.63). There were significant changes in spatiotemporal metrics, but their magnitude was minor and did not differ between the groups. There were no significant changes in running kinematics within or between groups. However, alterations in running biomechanics beyond typical session‐to‐session variation were observed during some in‐field sessions for individuals that received real‐time feedback.
Conclusion
Alterations in running biomechanics as observed during some in‐field sessions for individuals receiving wearable‐based real‐time feedback did not result in significant differences in running economy or running biomechanics when measured in controlled lab conditions without feedback.
... It has been reported that greater inertial loads to the rectus femoris during the early swing phase increase patellar tension, leading to the risk of patellofemoral pain in running. 51 Another example would be chronic exertional compartment syndrome induced by tibialis anterior overload 52 ; the previous varied foot COM estimation and the current overestimation of ankle and knee joint kinetics may result in an overestimation of injury risk. Altogether, the results of the present study indicate speed as a factor that could exacerbate overestimation by markerless systems which, if used in sports biomechanics, could lead to inaccurate estimation of running-related injury risk. ...
Background
The development of computer vision technology has enabled the use of markerless movement tracking for biomechanical analysis. Recent research has reported the feasibility of markerless systems in motion analysis but has yet to fully explore their utility for capturing faster movements, such as running. Applied studies using markerless systems in clinical and sports settings are still lacking. Thus, the present study compared running biomechanics estimated by marker-based and markerless systems. Given running speed not only affects sports performance but is also associated with clinical injury prevention, diagnosis, and rehabilitation, we aimed to investigate the effects of speed on the comparison of estimated lower extremity joint moments and powers between markerless and marker-based technologies during treadmill running as a concurrent validating study.
Methods
Kinematic data from marker-based/markerless technologies were collected, along with ground reaction force data, from 16 young adults running on an instrumented treadmill at 3 speeds: 2.24 m/s, 2.91 m/s, and 3.58 m/s (5.0 miles/h, 6.5 miles/h, and 8.0 miles/h). Sagittal plane moments and powers of the hip, knee, and ankle were calculated by inverse dynamic methods. Time series analysis and statistical parametric mapping were used to determine system differences.
Results
Compared to the marker-based system, the markerless system estimated increased lower extremity joint kinetics with faster speed during the swing phase in most cases.
Conclusion
Despite the promising application of markerless technology in clinical settings, systematic markerless overestimation requires focused attention. Based on segment pose estimations, the centers of mass estimated by markerless technologies were farther away from the relevant distal joint centers, which led to greater joint moments and powers estimates by markerless vs. marker-based systems. The differences were amplified by running speed.
... Some research suggests that running with rear-foot strikes is associated with greater injury (e.g., Arendse et al., 2004;Daoud et al., 2012), especially an increase in knee-impact injuries. Moreover, runners who run with mid-foot strikes and front-foot strikes tend to use shorter stride length or stride reach, and increased step rate or cadence (Heiderscheit et al., 2011;Kumar et al., 2015). These strike patterns are desirable to promote running technique when knee-impact injuries are a concern. ...
Correct running form is important for injury prevention; as such, correct form promotes continued engagement in running as a long-term form of exercise. Researchers have shown video feedback to be an effective strategy to improve athletic form for a variety of sports, but it has not been evaluated in any behavior analytic research as a method for improving running form. The purpose of this study is to evaluate the effectiveness of video feedback to improve running form for regular runners. During baseline, each participant was video recorded while running without any feedback (verbal or video). During intervention, the researcher recorded the participant, then showed them the video and provided feedback on correct or incorrect form, according to a 9-step task analysis. Results show that all three participants achieved 100% correct steps on the task analysis when video feedback was used to maintain their form during follow-up. K E Y W O R D S feedback, injury, running form, video analysis, video feedback
... NBFP showed a significant increase for the control insole, whereas PPFP decreased compared to the other two insoles. Increased braking force and decreased propulsive force change the original trajectory of COM and slow down the forward motion of COM in the sagittal plane (Heiderscheit et al., 2011). This may lead to greater resistance during forward running, affecting gait fluency during running. ...
... (8) However, an increase in cadence would reduce impact forces and loads on the joints of the lower limbs. (18)(19)(20) This phenomenon could represent a post-operative adaptive mechanism for reduction of stress on the knee joint, which would explain the increase in cadence found in the ACLR group compared to the control group. ...
Introduction: The main objective of this study was to evaluate whether running after anterior cruciate ligament reconstruction (ACLR) resulted in increased muscular activity of the gastrocnemius medialis and gastrocnemius lateralis compared to running in healthy participants. The secondary objective was to assess whether these changes in muscular activity correspond to changes in cadence, vertical stiffness, flight time and ground contact time while running.
Methods: This pilot case-control study included 7 patients with hamstring graft at 6 postoperative months (208.7 days ± 34.6) and 8 healthy athletes with no knee injury history. Two groups were formed, an ACLR group (n=7) and a control group (n=8). After maximal voluntary isometric contraction (MVIC) assessment, both groups performed treadmill running assessment with Optogait®. After a 6 minutes warm up on a treadmill at 10 km.h-1, (1) 30 sec were recorded to measure the surface electromyographical activity (EMG) of the GM and GL. (2,3) After root mean square (RMS) treatment of the raw signal, RMS EMG results were normalized by MVIC activity to allow inter-subject comparability.
Results: Between-group analyses showed a significant increase in RMS EMG for the ACLR group compared to the control group for the GM (34.7%MVIC ± 11.0 vs 25.5%MVIC ± 13.0, p = 0.05, Effect Size = 0.52) and the GL (32.8%MVIC ± 10.6 vs 17.2%MVIC ± 6.30, p < 0.01, Effect Size = 0.78). Significant correlation was observed in the ACLR group with GL RMS EMG for ground contact time (r = 0.84; p = 0.02). However, there were no significant correlations with cadence (r = 0.50; p = 0.27), vertical stiffness (r = 0.50; p = 0.27) and flight time (r = 0.02; p = 0.97). No significant correlations were observed in the ACLR group with GM RMS EMG.
Conclusion: These findings indicate that ACLR subjects presented with higher GM and GL activity while running compared to the control group. The overuse of these muscles may play a role in the alteration of spatiotemporal parameters of running after ACLR.
... One of the key biomechanical parameters of high-performance running is cadence, which is the number of steps per minute (spm) (Moore, 2016). Increasing running cadence can improve running performance by reducing joint stress and muscle fatigue (Heiderscheit et al., 2011). The optimal proven cadence is between 170 and 190 spm for long-distance runners (Moore, 2016). ...
Problem Statement: This systematic review focuses on the use of sensors to improve performance in endurance athletes by analyzing biomechanical parameters. Approach: The use of sensors in endurance sports has gained popularity in recent years, allowing athletes and coaches to measure and analyze different biomechanical parameters in real-time. Purpose: The main purpose of this systematic review is to answer the question of how sensors can be used and applied to improve performance in endurance runners by analyzing the biomechanical parameters they provide. Methods: Systematic review analyzing related keywords such as biomechanics, kinematics, kinetics, running, triathlon, ultra running, trail running, Stryd, SHFT, Runscribe, and performance, through scientific research articles from the database of the Electronic Library of the Isabel I University dated 02/2023 in English. A total of 192 investigations were found, of which 168 were excluded. After a detailed review, 15 relevant investigations were included. Results: Sensors can be useful to measure biomechanical parameters such as cadence, stride length, leg spring stiffness, ground contact time, and vertical oscillation, which can help to improve performance in endurance athletes. Conclusions: Sensors are a suitable tool to analyze performance improvement in endurance athletes by analyzing biomechanical parameters. However, it is important to highlight that not all sensors are similar, that it is necessary to carefully select the most suitable ones for each specific situation, and that biomechanics is also conditioned in each athlete, so universal rules cannot be established.
... For example, Gerrard and Bonanno (2018) found that increasing step rate (reducing GCT and stride length) significantly reduced peak plantar pressure. In addition, increasing stride frequency (and by proxy reducing GCT) has been associated with reduced metabolic cost, braking impulses, vertical oscillations of the COM, vGRF and tibial acceleration, and loading at the hip and knee (Anderson et al., 2022;Chumanov et al., 2012;Derrick et al., 1998;Farley & González, 1996;Heiderscheit et al., 2011;Lenhart et al., 2014;Lieberman et al., 2015;Mercer et al., 2003;Morin et al., 2007;Schubert et al., 2014;Seay et al., 2008;Stergiou et al., 2003). Therefore, our meta-analysis reveals no significant difference in GCT when running on hard or soft surfaces. ...
The surface upon which running is performed has been suggested as a potential cause of many running-related injuries. It remains unclear, however, what effect surface compliance has on running biomechanics. This study aimed to investigate the effect of surface compliance on overground running biomechanics through a systematic review and meta-analysis. Using the PRISMA Protocols Statement, a search was conducted in three electronic databases (CINAHL, EMBASE, EBSCO) using the following anchoring terms: running, overground surface, biomechanics, kinematics, tibial acceleration, pressure and force. Following de-duplication, title/abstract screening and full-text review, 25 articles (n = 492) were identified which met all inclusion criteria, 22 (n = 392) of which were subsequently included in quantitative synthesis. Random effects analysis found that peak tibial acceleration was significantly lower when running on softer surfaces (P = 0.01, Z = 2.51; SMD = -0.8; 95% CI =-1.42 to -0.18). However, peak vertical ground reaction force, loading rate and ground contact time were not significantly different when comparing hard and soft surfaces. Since peak tibial acceleration has been associated with an increased risk of tibial stress injuries, the results of this meta-analysis suggest that running on softer surfaces to reduce impact stress on the tibia is probably justified to lower the risk of running-related stress injuries.
... As such, those with PWS may not generate sufficient braking force to decelerate the body during each step contributing to gait instability. Alternatively, larger braking forces have been associated with greater energy absorption at the knee and hip during running gait (Heiderscheit et al., 2011). As such, future studies are needed to determine optimal loading parameters during gait or other weight-bearing activities for bone development in individuals with PWS. ...
Introduction:
The incidence of osteopenia and osteoporosis is of concern in adults with Prader-Willi syndrome (PWS). Walking generates reaction forces that could stimulate bone mineralization and is popular in people with PWS. This study compared bone parameters and ground reaction forces (GRF) during gait between young adults with PWS and without PWS and explored associations between bone and GRFs during gait.
Methods:
10 adults with PWS, 10 controls with obesity (OB) and 10 with normal weight (NW) matched on sex participated. Segmental and full body dual-energy x-ray absorptiometry scans provided femoral neck, spine, total body minus the head bone mineral density (BMD), bone mineral content (BMC). Vertical GRF, vertical impulse, posterior force and negative impulse were measured during 5 walking trials at a self-selected speed along a 10 m runway.
Results:
Multivariate analyses of variance showed that adults with PWS (n = 7-8) had hip and body BMD and BMC comparable (p > .050) to NW and lower (p < .050) than OB. Adults with PWS showed slower speed than NW (p < .050) but similar to OB (p > .050). Adults with PWS presented lower absolute vertical GRF, vertical impulse and negative impulse than OB (p < .050). Pearson r correlations (p < .050) in those with PWS (n = 7-8) indicated that femoral neck BMC was associated with vertical GRF (r = 0.716), vertical impulse (r = 0.780), posterior force (r = -0.805), and negative impulse (r = -0.748). Spine BMC was associated with speed (r = 0.829) and body BMD was associated with speed (r = 0.893), and posterior force (r = -0.780).
Conclusions:
Increased BMC in the femoral neck and body were associated with larger breaking forces during walking, a phenomenon normally observed at greater gait speeds. Faster walking speed was associated with greater BMC in the spine and body. Our preliminary results suggest that young adults with PWS could potentially benefit from faster walking for bone health; however, larger prospective studies are needed to confirm this.
Context
There is little evidence to guide elite athletes who desire returning to competition after giving birth to a child. Ultimately, this can result in decreased performance and increased risk of injury. This paper addresses aspects that must be considered when building and monitoring a return to running program for a postpartum elite or subelite athlete, including pelvic floor and core stability, progressive reloading of the musculoskeletal system, monitoring of nutritional parameters, and considerations for lactation.
Evidence Acquisition
PubMed and CINAHL (Cumulative Index for Nursing and Allied Health Literature) were searched with the following search strategy: (extreme sports OR elite athletes OR running OR exercise) AND (breastfeeding OR lactation OR bone density OR fetal weight OR gestational weight gain OR postpartum or post-partum OR postnatal OR post-natal OR pregnancy OR childbirth). The following information is based on best available evidence and clinical experience.
Study Design
Clinical review.
Level of Evidence
Level 4.
Results
Due to the interplay between cardiovascular fitness, postpartum nutrition, lactation, and progressive reloading of the muscular and skeletal system, we propose a multimodal, multidisciplinary approach to safely and successfully allow an athlete to return to an elite level of competition.
Conclusion
Return to running in the postpartum period is a highly individualized process that benefits from multidisciplinary, individualized care. This includes monitoring of nutrition, core and pelvic floor function, bone reloading, muscle and tendon reloading, and breastfeeding care when applicable.
Strengh of recommendation taxonomy (SORT)
C.
Background
Current literature suggests positive outcomes for patients participating in telemedicine physical therapy after total joint replacements, with limited reports for other orthopaedic conditions. Telemedicine physical therapy may be an effective method for providing skilled treatment to patients with running-related pain.
Case Presentation
These case reports describe 2 runners presenting to physical therapy with a chief complaint of the inability to run, due to hip or knee pain. Both patients were evaluated in person at the Boston University Physical Therapy Center and received subsequent care via telemedicine. Intervention included specific exercise, neuromuscular education, and progression of return to running.
Outcome and Follow-Up
At discharge, both patients demonstrated improved motor control with functional testing, successful return to running, and clinically significant improvements in all patient-reported outcomes.
Discussion
These case reports could serve as a reference for physical therapists to consider the use of telemedicine for return-to-running training when patients are unable to attend in-person clinics. JOSPT Cases 2022;2(1):13–17. doi:10.2519/josptcases.2022.10191
The objective of this thesis was to determine the effect of fatigue on impact shock wave attenuation and assess how human biomechanics relate to shock attenuation during running. In this paper, we propose a new methodology for the analysis of shock events occurring during the proposed experimental procedure. Our approach is based on the Shock Response Spectrum (SRS), which is a frequency-based function that is used to indicate the magnitude of vibration due to a shock or a transient event. Five high level CrossFit athletes who ran at least three times per week and who were free from musculoskeletal injury volunteered to take part in this study. Two Micromachined Microelectromechanical Systems (MEMS) accelerometers (RunScribe®, San Francisco, CA, USA) were used for this experiment.Injuries in running are often provoked by fatigue or improper technique, which are both reflected in the runner’s kinematics. State of the art research on kinetics and kinematics in sports is using motion analysis systems that are inaccessible to most athletes. The potential of wearable sensors for runners’ kinetic and kinematics analysis is extremely relevant and cost effective. Throughout our research we demonstrate the potential of wearable sensors for runners’ kinetic and kinematics analysis. We present several studies using inertial measurement units (IMU) for performance level assessment, training assistance, and fatigue monitoring. We extracted many gait parameters for performance and health assessments. Wearable sensors provide a valuable tool for runners, from beginners to experts, for running technique assessment.Our hypothesis is that fatigue leads to a decrease in the shock attenuation capacity of the musculoskeletal system, thus potentially implying a higher risk of overuse injury
Background
The literature on the running kinematics of youth distance runners is limited.
Purpose
We sought to describe 2-dimensional (2D) video analysis of running kinematics in healthy adolescent distance runners, which has not been previously described.
Methods
We conducted an observational study of healthy, competitive runners between the ages of 14 and 18 years, prospectively recruited through local running clubs and our hospital’s outreach between August 2019 and July 2023. Participants ran on a treadmill at a self-selected speed with markers attached to the thorax, pelvis, and lower extremities. A high-definition video camera recorded the runners in the sagittal and frontal planes. Kinematic measurements were completed using Dartfish software and reported as means and standard deviations.
Results
Of the 53 participants (51% boys, mean age: 16.0 ± 1.4 years) included in the 2D running analysis, 91% ran with a rearfoot strike pattern, with a mean foot inclination angle of 10.2° ± 6.2°. Knee flexion angle at initial contact was 13.2° ± 3.8°, tibia inclination angle was 8.5° ± 3.2°, and peak knee flexion was 44.5° ± 3.6°. Cadence was 168.7° ± 8.6°. Contralateral pelvic drop was 6.0° ± 2.2° and peak rearfoot eversion was 11.8° ± 3.6°.
Conclusions
This study is the first to describe running kinematics as captured by 2D video in healthy adolescent runners and to identify kinematic variables that may differ from those of adult runners. Further research is required to determine if adult recommendations are applicable to adolescent populations.
Purpose
Understanding muscle-tendon forces (e.g., triceps surae and Achilles tendon) during locomotion may aid in the assessment of human performance, injury risk, and rehabilitation progress. Shear wave tensiometry is a noninvasive technique for assessing in vivo tendon forces that has been recently adapted to a wearable technology. However, previous lab-based and outdoor tensiometry studies have not evaluated running. This study was undertaken to assess the capacity for shear wave tensiometry to produce valid measures of Achilles tendon loading during running at a range of speeds.
Methods
Participants walked (1.34 m/s) and ran (2.68, 3.35, and 4.47 m/s) on an instrumented treadmill while shear wave tensiometers recorded Achilles tendon wave speeds simultaneously with whole body kinematic and ground reaction force data. A simple isometric task allowed for the participant-specific conversion of Achilles tendon wave speeds to forces. Achilles tendon forces were compared to ankle torque measures obtained independently via inverse dynamics analyses. Differences in Achilles tendon wave speed, Achilles tendon force, and ankle torque across walking and running speeds were analyzed with linear mixed-effects models.
Results
Achilles tendon wave speed, Achilles tendon force, and ankle torque exhibited similar temporal patterns across the stance phase of walking and running. Significant monotonic increases in peak Achilles tendon wave speed (56.0-83.8 m/s), Achilles tendon force (44.0-98.7 N/kg), and ankle torque (1.72-3.68 N-m/kg) were observed with increasing locomotion speed (1.34-4.47 m/s). Tensiometry estimates of peak Achilles tendon force during running (8.2-10.1 body weights) were within the range of those estimated previously via indirect methods.
Conclusions
These results set the stage for using tensiometry to evaluate Achilles tendon loading during unobstructed athletic movements, such as running, performed in the field.
OBJECTIVES: To (1) assess relationships between running biomechanics, bone health, and bone stress injuries (BSIs), and (2) determine which variables constitute the most parsimonious BSI risk model among collegiate cross-country runners.
DESIGN: Prospective, observational cohort study.
METHODS: Running gait and bone mineral density (BMD) data from healthy collegiate cross-country runners were collected at preseason over 6 seasons. A generalized estimating equation model with backward selection was used to develop the most parsimonious model for estimating BSI risk, controlling for sex, running speed, and prior BSI. The variables assessed were spatiotemporal, ground reaction force, and joint kinematics, based on previous literature. Quasi-likelihood under the independence model criterion values and R ² values were used to select the best-fitting model.
RESULTS: Data from 103 runners were included in the analysis. The best-fitting model included vertical center of mass (COM) displacement and BMD z-score. Injury risk increased with greater vertical COM displacement (unit = 0.5 cm; relative risk [RR] = 1.14; 95% confidence interval [CI]: 1.01, 1.29; P = .04) and decreased with greater BMD z-score (unit = 0.5; RR = 0.83; 95% CI: 0.72, 0.95; P = .007). The model performed similarly when step rate was included instead of vertical COM displacement.
CONCLUSION: Vertical COM displacement and BMD z-score contributed to the best model for estimating risk the risk of bone stress injury in cross-country runners. Step rate was also an important variable for assessing injury risk. J Orthop Sports Phys Ther 2023;53(12):761-768. Epub 20 October 2023. doi:10.2519/jospt.2023.11860
Purpose:
The primary goal of this study was to examine changes in peak insole force and cumulative weighted peak force (CWPF)/km with increased step rate in collegiate runners. The secondary goal was to determine whether sacral acceleration correlates with insole force when increasing step rate.
Methods:
12 collegiate distance runners ran 1000 m outdoors at 3.83 m/s at preferred and 10% increased step rates while insole force and sacral acceleration were recorded. CWPF/km was calculated from insole force based on cumulative damage models. The effects of step rate on peak insole force and CWPF/km were tested using paired t-tests or Wilcoxon tests. Correlation coefficients between peak axial (approximately vertical) sacral acceleration times body mass and peak insole force were calculated on cohort and individual levels.
Results:
Peak insole force and CWPF/km decreased (p < 0.001) with increased step rate. Peak axial sacral acceleration did not correlate with peak insole force on the cohort level (r = 0.35, p = 0.109) but did within individuals (mean r = 0.69-0.78, p < 0.05).
Conclusions:
Increasing step rate may reduce peak vGRF and CWPF/km in collegiate runners. Therefore, clinicians should consider step rate interventions to reduce peak and cumulative vGRF in this population. Individual-specific calibrations may be required to assess changes in peak vGRF in response to increasing step rate using wearable accelerometers.
Human locomotion has been modeled as a force-driven harmonic oscillator (FDHO). The minimum forcing function in locomotion has been shown to occur at the resonant frequency of the FDHO and results in the suggestion that oxygen cost may be considered an optimality criterion for locomotion. The purposes of this study were twofold: first, to determine the relationship between stride frequency and shock attenuation, and second, to determine whether shock attenuation may also be considered an optimality criterion. Ten healthy young adult males served as subjects in this study. Each subject's preferred running speed and preferred stride frequency (PSF) were determined. In addition to the PSF, they ran at stride frequencies corresponding to −20%, −10%, +10%, and +20% of the PSF at the preferred running speed. Metabolic data as well as leg and head acceleration data were collected during a steady state run at each of the stride frequency conditions. The metabolic data produced a U-shaped curve hypothesized by the FDHO model. Spectral analysis on the leg and head acceleration data were used to develop transfer functions for each of the stride frequency conditions. Analysis of the transfer function indicated that there was a gain at the low frequencies and an attenuation at the higher frequencies. The transfer function at the higher frequencies indicated that the impact shock signal was attenuated as it passed through the body. However, the transfer functions appeared to vary according to the amount of shock input to the system with the result that the head accelerations remained constant. It would appear that impact (high frequency) shock attenuation increases with stride frequency and thus does not fit the FDHO model as an optimization criterion. At all stride frequencies, regardless of the impact shock, head accelerations were maintained at a constant level.
Single-subject with repeated measures.
To determine if runners can use real-time visual feedback from an accelerometer to achieve immediate reductions in tibial acceleration and vertical-force loading rates.
Stress fractures are a common injury among runners. Previous studies suggest that runners with higher than normal tibial acceleration and vertical-force loading rates are at increased risk for tibial stress fractures. If these runners can be trained to reduce the loading on their lower extremities, it may reduce their risk of stress fractures.
Five subjects participated in this study. All subjects ran on a treadmill, instrumented with force transducers, during a single 30-minute session that was divided into warm-up, feedback, no-feedback, and cool-down periods. During running, the subjects also wore an accelerometer taped to their distal right tibia. Peak positive acceleration of the tibia, vertical force impact peak, and average and instantaneous vertical-force loading rates were assessed at the end of the warm-up, feedback, and no-feedback periods.
Single-subject analysis revealed that 4 of the 5 subjects had significant reductions in their peak positive acceleration at the end of the no-feedback period compared to the warm-up. In addition, all of the subjects had significant decreases in impact peak and vertical ground reaction force loading rates at the end of the no-feedback period.
In a single session of training with real-time visual feedback, it appears that most runners can reduce the types of lower extremity loading associated with stress fractures. This may lead to training programs that reduce the risk of stress fractures for runners.
Cross-sectional experimental laboratory study.
To examine differences in running mechanics between runners who had previously sustained iliotibial band syndrome (ITBS) and runners with no knee-related running injuries.
ITBS is the second leading cause of knee pain in runners and the most common cause of lateral knee pain. Despite its prevalence, few biomechanical studies have been conducted to better understand its aetiology. Because the iliotibial band has both femoral and tibial attachments, it is possible that atypical hip and foot mechanics could result in the development of ITBS.
The running mechanics of 35 females who had previously sustained ITBS were compared to 35 healthy age-matched and running distance-matched healthy females. Comparisons of hip, knee, and ankle 3-dimensional kinematics and internal moments during the stance phase of running gait were measured.
The ITBS group exhibited significantly greater peak rearfoot invertor moment, peak knee internal rotation angle, and peak hip adduction angle compared to controls. No significant differences in peak rearfoot eversion angle, peak knee flexion angle, peak knee external rotator moment, or peak hip abductor moments were observed between groups.
Females with a previous history of ITBS demonstrate a kinematic profile that is suggestive of increased stress on the iliotibial band. These results were generally similar to those reported for a prospective study conducted within the same laboratory environment.
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.
In this study, we assessed how ungraded jogging and graded walking at the same rating of perceived exertion (RPE) affect heart rate and oxygen consumption ([Vdot]O(2)). Twenty untrained participants completed a treadmill test to determine peak [Vdot]O(2) (mean = 40.3 +/- 6.3 ml . kg(-1) . min(-1)). Participants completed separate 30-min trials of moderate exercise (RPE of 13 on the Borg 6-20 scale) in random order on the treadmill: graded walking and ungraded jogging. Treadmill speed or grade was adjusted throughout the trial by the experimenter based on participant responses to maintain an RPE of 13. The jogging trial produced a significantly higher heart rate (161 +/- 18 vs. 142 +/- 24 beats . min(-1)) and [Vdot]O(2) (7.4 +/- 1.8 vs. 5.8 +/- 1.5 METs) (P < 0.01) than the walking trial. Treadmill grade decreased significantly during the walking trial (11.1 +/- 2.3% to 10.0 +/- 2.2%; P < 0.01), but treadmill speed did not change significantly during the jogging trial (5.2 +/- 1.0 miles . h(-1) to 5.0 +/- 0.9 miles . h(-1)) (P > 0.05), in an effort to maintain constant RPE. These findings provide evidence that similar perceptions of effort during graded walking and ungraded jogging do not produce similar cardiovascular and metabolic responses. The results indicate that, for a given prescribed perceived effort, jogging provides a greater stimulus for fitness benefits and caloric expenditure.
Controlled laboratory study using a cross-sectional design.
To determine whether females with patellofemoral pain (PFP) demonstrate differences in hip kinematics, hip muscle strength, and hip muscle activation patterns when compared to pain-free controls.
It has been proposed that abnormal hip kinematics may contribute to the development of PFP. However, research linking hip function to PFP remains limited.
Twenty-one females with PFP and 20 pain-free controls participated in this study. Hip kinematics and activity level of hip musculature were obtained during running, a drop jump, and a step-down maneuver. Isometric hip muscle torque production was quantified using a multimodal dynamometer. Group differences were assessed across tasks using mixed-design 2-way analyses of variance and independent t tests.
When averaged across all 3 activities, females with PFP demonstrated greater peak hip internal rotation compared to the control group (mean +/- SD, 7.6 degrees +/- 7.0 degrees versus 1.2 degrees +/- 3.8 degrees; P<.05). The individuals in the PFP group also exhibited diminished hip torque production compared to the control group (14% less hip abductor strength and 17% less hip extensor strength). Significantly greater gluteus maximus recruitment was observed for individuals in the PFP group during running and the step-down task.
The increased peak hip internal rotation motion observed for females in the PFP group was accompanied by decreased hip muscle strength. The increased activation of the gluteus maximus in individuals with PFP suggests that these subjects were attempting to recruit a weakened muscle, perhaps in an effort to stabilize the hip joint. Our results support the proposed link between abnormal hip function and PFP.
We have developed a model of the human lower extremity to study how surgical changes in musculoskeletal geometry and musculotendon parameters affect muscle force and its moment about the joints. The lines of action of 43 musculotendon actuators were defined based on their anatomical relationships to three-dimensional bone surface representations. A model for each actuator was formulated to compute its isometric force-length relation. The kinematics of the lower extremity were defined by modeling the hip, knee, ankle, subtalar, and metatarsophalangeal joints. Thus, the force and joint moment that each musculotendon actuator develops can be computed for any body position. The joint moments calculated with the model compare well with experimentally measured isometric joint moments. We developed a graphical interface to the model that allows the user to visualize the musculoskeletal geometry and to manipulate the model parameters to study the biomechanical consequences of orthopaedic surgical procedures. For example, tendon transfer and lengthening procedures can be simulated by adjusting the model parameters according to various surgical techniques. Results of the simulated surgeries can be analyzed quickly in terms of postsurgery muscle forces and other biomechanical variables. Just as interactive graphics have enhanced engineering design and analysis, we have found that graphics-based musculoskeletal models are effective tools for designing and analyzing surgical procedures.
A three-dimensional model of the human body is used to simulate a maximal vertical jump. The body is modeled as a 10-segment, 23 degree-of-freedom (dof), mechanical linkage, actuated by 54 muscles. Six generalized coordinates describe the position and orientation of the pelvis relative to the ground; the remaining nine segments branch in an open chain from the pelvis. The head, arms, and torso (HAT) are modeled as a single rigid body. The HAT articulates with the pelvis via a 3 dof ball-and-socket joint. Each hip is modeled as a 3 dof ball-and-socket joint, and each knee is modeled as a 1 dof hinge joint. Each foot is represented by a hindfoot and toes segment. The hindfoot articulates with the shank via a 2 dof universal joint, and the toes articulate with the hindfoot via a 1 dof hinge joint. Interaction of the feet with the ground is modeled using a series of spring-damper units placed under the sole of each foot. The path of each muscle is represented by either a series of straight lines or a combination of straight lines and space curves. Each actuator is modeled as a three-element, Hill-type muscle in series with tendon. A first-order process is assumed to model muscle excitation-contraction dynamics. Dynamic optimization theory is used to calculate the pattern of muscle excitations that produces a maximal vertical jump. Quantitative comparisons between model and experiment indicate that the model reproduces the kinematic, kinetic, and muscle-coordination patterns evident when humans jump to their maximum achievable heights.
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 literature related to Borg's ratings of perceived exertion (RPE) scale has revealed inconsistencies about the strength of the relationship between ratings of perceived exertion and various physiological criterion measures, such as heart rate, blood lactate concentration, percent maximal oxygen uptake (%VO2max), oxygen uptake (VO2), ventilation and respiration rate. Using sex of participants, fitness, type of RPE scale used, type of exercise, exercise protocol, RPE mode and study quality, we undertook a meta-analysis to determine the strength of the relationship between RPE scores and the six aforementioned physiological measures. The weighted mean validity coefficients were 0.62 for heart rate, 0.57 for blood lactate, 0.64 for %VO2max 0.63 for VO2, 0.61 for ventilation and 0.72 for respiration rate. Analysis of moderator variables revealed that the following study features could account for the variation of results across studies: heart rate--fitness, type of exercise, protocol and RPE mode; blood lactate concentration--sex, RPE scale; VO2--sex, exercise type, RPE mode; ventilation--sex, RPE mode; respiration rate--exercise protocol, RPE mode. The highest correlations between ratings of perceived exertion and the various physiological criterion measures were found in the following conditions: when male participants (whose VO2 or ventilation was measured) were required to maximally exert themselves (measuring %VO2max or ventilation); when the exercise task was unusual [e.g. when participants were swimming, which is less common than walking or running (when heart rate, %VO2max and VO2 are measured)]; or when the 15-point RPE scale (measuring blood lactate concentration) was used. These findings suggest that although Borg's RPE scale has been shown to be a valid measure of exercise intensity, its validity may not be as high as previously thought (r = 0.80-0.90), except under certain conditions.
In this study, we examined the consequences of a global alteration in running technique on running kinematics and running economy in triathletes. Sixteen sub-elite triathletes were pre and post tested for running economy and running kinematics at 215 and 250 m.min-1. The members of the treatment group (n=8) were exposed to 12 weeks of instruction in the "pose method" of running, while the members of the control group (n=8) maintained their usual running technique. After the treatment period, the experimental group demonstrated a significant decrease in mean stride length (from 137.25+/-7.63 cm to 129.19+/-7.43 cm; P<0.05), a post-treatment difference in vertical oscillation compared with the control group (6.92+/-1.00 vs. 8.44+/-1.00 cm; P<0.05) and a mean increase in submaximal absolute oxygen cost (from 3.28+/-0.36 l.min-1 to 3.53+/-0.43 l.min-1; P<0.01). The control group exhibited no significant changes in either running kinematics or oxygen cost. The global change in running mechanics associated with 12 weeks of instruction in the pose method resulted in a decrease in stride length, a reduced vertical oscillation in comparison with the control group and a decrease of running economy in triathletes.
This article outlines the practical management of iliotibial band friction syndrome (ITBFS) in running athletes. ITBFS is the most common cause of lateral knee pain in runners and is related to repetitive friction of the iliotibial band sliding over the lateral femoral epicondyle. Runners predisposed to this injury are typically in a phase of over training and often have underlying weakness of the hip abductor muscles. The diagnosis of ITBFS is clinical and is based on a thorough patient history and physical exam. In the acute phase, treatment includes activity modification, ice, nonsteroidal anti-inflammatory medication, and corticosteroid injection in cases of severe pain or swelling. During the subacute phase emphasis is on stretching of the iliotibial band and soft tissue therapy for any myofascial restrictions. The recovery phase focuses on a series of exercises to improve hip abductor strength and integrated movement patterns. The final return to running phase is begun with an every other day program, starting with easy sprints and avoidance of hill training with a gradual increase in frequency and intensity. In rare refractory cases that do not respond to conservative treatment, surgery can be considered.
The purpose of this study was to present a systematic overview of published reports on the incidence and associated potential risk factors of lower extremity running injuries in long distance runners. An electronic database search was conducted using the PubMed-Medline database. Two observers independently assessed the quality of the studies and a best evidence synthesis was used to summarise the results. The incidence of lower extremity running injuries ranged from 19.4% to 79.3%. The predominant site of these injuries was the knee. There was strong evidence that a long training distance per week in male runners and a history of previous injuries were risk factors for injuries, and that an increase in training distance per week was a protective factor for knee injuries.
The higher oxygen consumption reported when shod running is compared to barefoot running has been attributed to the additional mass of the shoe. However, it has been reported that wearing shoes also modified the running pattern. The aim of this study was to distinguish the mass and shoe effects on the mechanics and energetics when shod running. Twelve trained subjects ran on a 3-D treadmill ergometer at 3.61 m . s (-1) in six conditions: barefoot, using ultra thin diving socks unloaded, loaded with 150 g, loaded with 350 g, and two shoe conditions, one weighing 150 g and another 350 g. The results show that there was a significant mass effect but no shoe effect for oxygen consumption. Stride frequency, anterior-posterior impulse, vertical stiffness, leg stiffness, and mechanical work were significantly higher in barefoot condition compared to shod. Net efficiency, which has metabolic and mechanical components, decreased in the shod condition. The mechanical modifications of running showed that the main role of the shoe was to attenuate the foot-ground impact by adding damping material. However, these changes may lead to a decrease of the storage and restitution of elastic energy capacity which could explain the lower net efficiency reported in shod running.
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.
The fatigue life of bone is inversely related to strain magnitude. Decreasing stride length is a potential mechanism of strain reduction during running. If stride length is decreased, the number of loading cycles will increase for a given mileage. It is unclear if increased loading cycles are detrimental to skeletal health despite reductions in strain.
To determine the effects of stride length and running mileage on the probability of tibial stress fracture.
Ten male subjects ran overground at their preferred running velocity during two conditions: preferred stride length and 10% reduction in preferred stride length. Force platform and kinematic data were collected concurrently. A combination of experimental and musculoskeletal modeling techniques was used to determine joint contact forces acting on the distal tibia. Peak instantaneous joint contact forces served as inputs to a finite element model to estimate tibial strains during stance. Stress fracture probability for stride length conditions and three running mileages (3, 5, and 7 miles x d(-1)) were determined using a probabilistic model of bone damage, repair, and adaptation. Differences in stress fracture probability were compared between conditions using a 2 x 3 repeated-measures ANOVA.
The main effects of stride length (P = 0.017) and running mileage (P = 0.001) were significant. Reducing stride length decreased the probability of stress fracture by 3% to 6%. Increasing running mileage increased the probability of stress fracture by 4% to 10%.
Results suggest that strain magnitude plays a more important role in stress fracture development than the total number of loading cycles. Runners wishing to decrease their probability for tibial stress fracture may benefit from a 10% reduction in stride length.
To examine the influence of the frequency of measurement on the rating of perceived exertion (RPE) during sub-maximal exercise. On two occasions participants performed 35 min sub-maximal treadmill exercise at the same running speed. In both runs RPE was measured after 5 min. Thereafter, RPE was measured at either 10-min intervals (RPE10 min), or 60-s intervals (RPE60 s) with the order of conditions controlled using a counter-balanced, cross-over design. The heart rate, VO(2) and RER were measured throughout each experimental trial. Significant differences in RPE between RPE60 s and RPE10 min were evident at 15, 25 and 35 min of exercise. No differences were evident between conditions in heart rate, VO(2) or RER. Differences in RPE between RPE60 s and RPE10 min indicate that the perception of exertion may be influenced by the act of measurement. The elevated RPE in RPE60 s may have been induced by an increased associative attentional focus.
The first aim of this study was to assess how changes in the mechanical characteristics of the foot/shoe-ground interface affect spatio-temporal variables, ground pressure distribution, sagittal plane kinematics, and running economy in 8 experienced barefoot runners. The second aim was to assess if a special lightweight shoe (Vibram Fivefingers) was effective in mimic the experience of barefoot running.
By using an instrumented treadmill, barefoot running, running with the Fivefingers, and running with standard running shoe were compared, analyzing a large numbers of consecutive steps. Foot/shoe-ground interface pressure distribution, lower limb kinematics, V.O(2) and heart rate data were simultaneously collected.
Compared to the standard shod condition when running barefoot the athletes landed in more plantarflexion at the ankle. This caused reduced impact forces and changes in stride kinematics. In particular, significantly shorter stride length and contact times and higher stride frequency were observed (P<0.05). Compared to standard shod condition, V.O(2) and peak impact forces were significantly lower with Fivefingers (P<0.05) and much closer to barefoot running. Lower limb kinematics with Fivefingers was similar to barefoot running with a foot position which was significantly more plantarflexed than in control shoe (P<0.05).
The data of this study support the assumption that changes in the foot-ground interface led to changes in running pattern in a group of experienced barefoot runners. The Fivefingers model seems to be effective in imitating the barefoot conditions while providing a small amount of protection.
Movement and muscle activity of the hip have been shown to affect movement of the lower extremity, and been related to injury. The purpose of this study was to determine if increased hip strength affects lower extremity mechanics during running.
Within subject, repeated measures design. Fifteen healthy women volunteered. Hip abduction and external rotation strength were measured using a hand-held dynamometer. Three-dimensional biomechanical data of the lower extremity were collected during running using a high-speed motion capture system. Measurements were made before, at the mid-point, and after a 6-week strengthening program using closed-chain hip rotation exercises. Joint range of motion (rearfoot eversion, knee abduction, hip adduction, and internal rotation), eversion velocity, eversion angle at heel strike, and peak joint moments (rearfoot inversion, knee abduction, hip abduction, and external rotation) were analyzed using repeated measures analysis of variance (P <or= 0.05). The independent variable was time (pre-, week 3, and week 6). A separate analysis of variance was conducted with the dependent variables of peak hip abduction and external rotation strength.
Hip abduction (P=0.009) and external rotation strength (P<0.0005) increased by 13% and 23%, respectively. Eversion range of motion decreased (P=0.05), hip adduction range of motion increased (P=0.05), and a trend of decreased hip internal rotation range of motion (P=0.08) were found. Rearfoot inversion moment (P=0.02) and knee abduction moment (P=0.05) decreased by 57% and 10%, respectively.
The hip abductors and external rotators were strengthened, leading to an alteration of lower extremity joint loading which may reduce injury risk. These exercises could be used in the rehabilitation, or prevention, of lower extremity injuries.
A computer model of 23 knees was obtained by embedding, slicing and digitizing the bone outlines and ligament co-ordinates. Using co-ordinate transformations, various three-dimensional motions were imposed on the knees, and calculations made of femoral-tibial contact error, contact point locations and ligament lengths. Significant deviations in these parameters were noted for abnormal motions including the elimination of internal-external rotation and a-p displacement and the misplacement of a hinge producing correct motion. The resulting mismatch could result in shear in soft tissues, cuff-to-skin slippage and inaccurate ligament length patterns.
An important determinant of the mechanics of running is the effective vertical stiffness of the body. This stiffness increases with running speed. At any one speed, the stiffness may be reduced in a controlled fashion by running with the knees bent more than usual. In a series of experiments, subjects ran in both normal and flexed postures on a treadmill. In other experiments, they ran down a runway and over a force platform. Results show that running with the knees bent reduces the effective vertical stiffness and diminishes the transmission of mechanical shock from the foot to the skull but requires an increase of as much as 50% in the rate of O2 consumption. A new dimensionless parameter (u omega 0/g) is introduced to distinguish between hard and soft running modes. Here, omega 0 is the natural frequency of a mass-spring system representing the body, g is gravity, and u is the vertical landing velocity. In normal running, this parameter is near unity, but in deep-flexed running, where the aerial phase of the stride cycle almost disappears, u omega 0/g approaches zero.
The purpose of this study was to determine the effects of systematic changes in stride rate and length at a given running speed on the peak shank deceleration (PSD) experienced during ground contact. Data were collected from 10 well-trained subjects as they ran on a treadmill at a pace of 3.8 m s-1 (7-min mile-1). Shank deceleration was measured by a lightweight accelerometer which was tightly attached over the distal medial tibia. High-speed films (200 Hz) were taken from a side view to quantify modifications in sagittal plane movement which might have accompanied the stride rate changes. Five stride rate conditions were randomly presented - 10% slower, 5% slower, normal, 5% faster and 10% faster. Average PSD was computed from 10 steps during each condition and testing was repeated on three different occasions. For each session, PSD observed for each condition was normalized to that observed at the normal stride rate in order to minimize the effects of variations in attachment of the accelerometer between and within subjects. The normalized PSD results at each stride rate tested were - normal = 1.0, 10% slower = 1.09, 5% slower = 1.03, 5% faster = 0.96 and 10% faster = 0.91. Significant differences were found between all these means except normal and 5% slower. The kinematic analysis revealed non-significant results for hip, knee and ankle joint angles at touchdown for the various stride rates. Application of the findings to existing analytical models indicated that, for a given running speed, peak impact forces in the ankle and knee joints decreased as stride rate increased.
Ten recreational runners (mean VO2max 64.7 ml . kg-1 . min-1) underwent a 5-d acclimation period to treadmill running at a 7 min . mile-1 pace (3.83 m . s-1) for 30 min each day. During these runs their freely chosen stride lengths were determined and expressed as a percentage of leg length (%LL). On two subsequent testing days stride length was systematically varied over a range of +/- 20% LL about the freely chosen value. O2 uptake was determined by the Douglas Bag method. All subjects exhibited a stride length of which O2 uptake was minimized, although the individual profiles varied considerably. The mean increases in VO2 were 2.6 and 3.4 ml . kg-1 . min-1 at the short- and long-stride length extremes, respectively. During unrestricted running deviations from optimal stride length caused a mean increase in VO2 of 0.2 ml . kg-1 . min-1. The relatively efficient running patterns used by the subjects during unrestricted running indicate either an adaption to the chosen stride length through training or a successful process of energy optimization.
When humans and other mammals run, the body's complex system of muscle, tendon and ligament springs behaves like a single linear spring ('leg spring'). A simple spring-mass model, consisting of a single linear leg spring and a mass equivalent to the animal's mass, has been shown to describe the mechanics of running remarkably well. Force platform measurements from running animals, including humans, have shown that the stiffness of the leg spring remains nearly the same at all speeds and that the spring-mass system is adjusted for higher speeds by increasing the angle swept by the leg spring. The goal of the present study is to determine the relative importance of changes to the leg spring stiffness and the angle swept by the leg spring when humans alter their stride frequency at a given running speed. Human subjects ran on treadmill-mounted force platform at 2.5ms-1 while using a range of stride frequencies from 26% below to 36% above the preferred stride frequency. Force platform measurements revealed that the stiffness of the leg spring increased by 2.3-fold from 7.0 to 16.3 kNm-1 between the lowest and highest stride frequencies. The angle swept by the leg spring decreased at higher stride frequencies, partially offsetting the effect of the increased leg spring stiffness on the mechanical behavior of the spring-mass system. We conclude that the most important adjustment to the body's spring system to accommodate higher stride frequencies is that leg spring becomes stiffer.
Zatsiorsky et al. (in Contemporary Problems in Biomechanics, pp. 272-291, CRC Press, Massachusetts, 1990a) obtained, by means of a gamma-ray scanning technique, the relative body segment masses, center of mass (CM) positions, and radii of gyration for samples of college-aged Caucasian males and females. Although these data are the only available and comprehensive set of inertial parameters regarding young adult Caucasians, they have been rarely utilized for biomechanical analyses of subjects belonging to the same or a similar population. The main reason is probably that Zatsiorsky et al. used bony landmarks as reference points for locating segment CMs and defining segment lengths. Some of these landmarks were markedly distant from the joint centers currently used by most researchers as reference points. The purpose of this study was to adjust the mean relative CM positions and radii of gyration reported by Zatsiorsky et al., in order to reference them to the joint centers or other commonly used landmarks, rather than the original landmarks. The adjustments were based on a number of carefully selected sources of anthropometric data.
For in vivo impact loadings administered under controlled initial conditions, it was hypothesized that larger initial knee angles (IKA) and softer impacting interfaces would reduce impact loading and initial leg stiffness. A human pendulum was used to deliver controlled impacts to the right foot of 21 subjects for three IKA (0, 20 and 40 degrees) and three interfaces (barefoot, soft and hard EVA foams). The external impact force and the shock experienced by the subjects' shank were measured simultaneously with a wall mounted force platform and a skin mounted accelerometer, respectively. Stiffness of the leg was derived using impact velocity and wall reaction force data. The results disproved the role of the knee joint in regulating initial leg stiffness and provided only partial support for the hypothesized improved cushioning. Larger knee flexion at contact reduced impact force but increased the shock travelling throughout the shank. Conversely, softer interfaces produced sizable reductions in both initial leg stiffness and severity of the impact experienced by the lower limb. Force rate of loading was found to be highly correlated (r = 0.95) to limb stiffness that was defined by the heel fat pad and interface deformations. These results would suggest that interface interventions are more likely to protect the locomotor system against impact loading than knee angle strategies.
A group of 304 runners enrolling in a marathon training program had alignment measurements performed and completed a questionnaire on training practices and injuries over the previous 12 months. The alignment measures consisted of arch index (AI), heel valgus (HV), knee tubercle-sulcus angle (TSA), knee varus (KV), and leg-length difference (LLD). Results indicated few consistent statistical associations between these alignment measures and risk of injuries, either bivariately or multivariately: left AI with hamstring injuries; right AI with shin injuries; right HV with back injuries; left TSA with ankle injuries; KV with hip injuries; and LLD with back, ankle, and foot injuries. A few statistically significant relationships were also found between other training and anthropometric factors and injuries: mileage with hamstring injuries; interval training with shin injuries; hard surfaces with back and thigh injuries; shoe use patterns with foot and overall injuries; and body mass index with heel injuries. We conclude that lower-extremity alignment is not a major risk factor for running injuries in our relatively low mileage cohort; however, prospective studies are necessary to confirm or refute these findings.
The foot-ground impact experienced during running produces a shock wave that is transmitted through the human skeletal system. This shock wave is attenuated by deformation of the ground/shoe as well as deformation of biological tissues in the body. The goal of this study was to investigate the locus of energy absorption during the impact phase of the running cycle.
Running speed (3.83 m x s[-1]) was kept constant across five stride length conditions: preferred stride length (PSL), +10% of PSL, -10% of PSL, +20% of PSL, and -20% of PSL. Transfer functions were generated from accelerometers attached to the leg and head of ten male runners. A rigid body model was used to estimate the net energy absorbed at the hip, knee, and ankle joints.
There was an increasing degree of shock attenuation as stride length increased. The energy absorbed during the impact portion of the running cycle also increased with stride length. Muscles that cross the knee joint showed the greatest adjustment in response to increased shock.
It was postulated that the increased perpendicular distance from the line of action of the resultant ground reaction force to the knee joint center played a role in this increased energy absorption.
Widespread use of gait or motion analysis in the diagnosis of patients with locomotor pathology and the subsequent planning and assessment of treatment has been limited because of its reliability, particularly in evaluating frontal and transverse plane components. This is because spatial reconstruction of the musculoskeletal system and calculation of its kinematics and kinetics via a skin marker-based multi-link model are subject to marker skin movement artefacts. Traditional methods treat each body segment separately without imposing joint constraints, resulting in apparent dislocations at joints predominantly because of skin movement artefacts. An optimisation method for the determination of the positions and orientations of multi-link musculoskeletal models from marker co-ordinates is presented. It is based on the minimisation of the weighted sum of squared distances between measured and model-determined marker positions. The model imposes joint constraints. Numerical experiments were performed to show that the new method is capable of eliminating joint dislocations and giving more accurate model position and orientation estimations. It is suggested that, with joint constraints and a global error compensation scheme, the effects of measurement errors on the reconstruction of the musculoskeletal system and subsequent mechanical analyses can be reduced globally. The proposed method minimises errors in axial rotation and ab/adduction at the joints and may extend the applicability of gait analysis to clinical problems.