Effects of a verbal and visual feedback system on running technique, perceived exertion and running economy in female novice runners

The Relationship Between Running Biomechanics and Running Economy: A Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

Running biomechanics is considered an important determinant of running economy (RE). However, studies examining associations between running biomechanics and RE report inconsistent findings.

OBJECTIVE

The aim of this systematic review was to determine associations between running biomechanics and RE and explore potential causes of inconsistency.

METHODS

Three databases were searched and monitored up to April 2023. Observational studies were included if they (i) examined associations between running biomechanics and RE, or (ii) compared running biomechanics between groups differing in RE, or (iii) compared RE between groups differing in running biomechanics during level, constant-speed, and submaximal running in healthy humans (18-65 years). Risk of bias was assessed using a modified tool for observational studies and considered in the results interpretation using GRADE. Meta-analyses were performed when two or more studies reported on the same outcome. Meta-regressions were used to explore heterogeneity with speed, coefficient of variation of height, mass, and age as continuous outcomes, and standardization of running shoes, oxygen versus energetic cost, and correction for resting oxygen or energy cost as categorical outcomes.

RESULTS

Fifty-one studies (n = 1115 participants) were included. Most spatiotemporal outcomes showed trivial and non-significant associations with RE: contact time r = - 0.02 (95% confidence interval [CI] - 0.15 to 0.12); flight time r = 0.11 (- 0.09 to 0.32); stride time r = 0.01 (- 0.8 to 0.50); duty factor r = - 0.06 (- 0.18 to 0.06); stride length r = 0.12 (- 0.15 to 0.38), and swing time r = 0.12 (- 0.13 to 0.36). A higher cadence showed a small significant association with a lower oxygen/energy cost (r = - 0.20 [- 0.35 to - 0.05]). A smaller vertical displacement and higher vertical and leg stiffness showed significant moderate associations with lower oxygen/energy cost (r = 0.35, - 0.31, - 0.28, respectively). Ankle, knee, and hip angles at initial contact, midstance or toe-off as well as their range of motion, peak vertical ground reaction force, mechanical work variables, and electromyographic activation were not significantly associated with RE, although potentially relevant trends were observed for some outcomes.

CONCLUSIONS

Running biomechanics can explain 4-12% of the between-individual variation in RE when considered in isolation, with this magnitude potentially increasing when combining different variables. Implications for athletes, coaches, wearable technology, and researchers are discussed in the review.

PROTOCOL REGISTRATION

https://doi.org/10.17605/OSF.IO/293 ND (OpenScience Framework).

Differences in running technique between runners with better and poorer running economy and lower and higher milage: An artificial neural network approach

BACKGROUND

Prior studies investigated selected discrete sagittal-plane outcomes (e.g., peak knee flexion) in relation to running economy, hereby discarding the potential relevance of running technique parameters during noninvestigated phases of the gait cycle and in other movement planes.

PURPOSE

Investigate which components of running technique distinguish groups of runners with better and poorer economy and higher and lower weekly running distance using an artificial neural network (ANN) approach with layer-wise relevance propagation.

METHODS

Forty-one participants (22 males and 19 females) ran at 2.78 m∙s-1 while three-dimensional kinematics and gas exchange data were collected. Two groups were created that differed in running economy or weekly training distance. The three-dimensional kinematic data were used as input to an ANN to predict group allocations. Layer-wise relevance propagation was used to determine the relevance of three-dimensional kinematics for group classification.

RESULTS

The ANN classified runners in the correct economy or distance group with accuracies of up to 62% and 71%, respectively. Knee, hip, and ankle flexion were most relevant to both classifications. Runners with poorer running economy showed higher knee flexion during swing, more hip flexion during early stance, and more ankle extension after toe-off. Runners with higher running distance showed less trunk rotation during swing.

CONCLUSION

The ANN accuracy was moderate when predicting whether runners had better, or poorer running economy, or had a higher or lower weekly training distance based on their running technique. The kinematic components that contributed the most to the classification may nevertheless inform future research and training.

Changes in running economy and running technique following 6 months of running with and without wearable-based real-time feedback

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.

Cultural variation in running techniques among non-industrial societies

Research among non-industrial societies suggests that body kinematics adopted during running vary between groups according to the cultural importance of running. Among groups in which running is common and an important part of cultural identity, runners tend to adopt what exercise scientists and coaches consider to be good technique for avoiding injury and maximising performance. In contrast, among groups in which running is not particularly culturally important, people tend to adopt suboptimal technique. This paper begins by describing key elements of good running technique, including landing with a forefoot or midfoot strike pattern and leg oriented roughly vertically. Next, we review evidence from non-industrial societies that cultural attitudes about running associate with variation in running techniques. Then, we present new data from Tsimane forager–horticulturalists in Bolivia. Our findings suggest that running is neither a common activity among the Tsimane nor is it considered an important part of cultural identity. We also demonstrate that when Tsimane do run, they tend to use suboptimal technique, specifically landing with a rearfoot strike pattern and leg protracted ahead of the knee (called overstriding). Finally, we discuss processes by which culture might influence variation in running techniques among non-industrial societies, including self-optimisation and social learning.

New evidence from the Tsimane underscores that running techniques vary between societies according to the cultural importance of running

The Effectiveness of Gait Retraining on Running Kinematics, Kinetics, Performance, Pain, and Injury in Distance Runners: A Systematic Review With Meta-analysis

OBJECTIVE

To evaluate the effectiveness of running gait retraining on kinematics, kinetics, performance, pain, and injury in distance runners.

DESIGN

Intervention systematic review with meta-analysis.

LITERATURE SEARCH

Seven electronic databases from inception to March 2021.

TRIAL SELECTION CRITERIA

Randomized controlled trials that (1) evaluated running gait retraining compared to no intervention, usual training, placebo, or standard care and (2) reported biomechanical, physiological, performance, or clinical outcomes.

DATA SYNTHESIS

Random-effects metaanalyses were completed, and the certainty of evidence was judged using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. We categorized interventions into step rate, non-rearfoot footstrike, impact, ground contact time, and multiparameter subgroups.

RESULTS

We included 19 trials (673 participants). Moderate-certainty evidence indicated step rate gait retraining increased step rate (SMD 1.03 [95% confidence interval {CI}: 0.63, 1.44]; number of trials (N): 4; I²: 0%) and reduced average vertical loading rate (SMD -0.57 [95% CI, -1.05 to -0.09], N: 3; I²: 0%). Low-certainty evidence indicated non-rearfoot footstrike retraining increased knee flexion at initial contact (SMD 0.74 [95% CI, 0.11 to 1.37]; N: 2; I²: 0%), but did not alter running economy (SMD 0.21 [95% CI, -1.11 to 1.52]; N: 3; I²: 19%).). Low-certainty evidence indicated multiparameter retraining did not alter running economy (SMD 0.32 [-0.39, 1.02]; N: 3; I²: 19%) or performance (SMD 0.14 [95% CI, -4.87 to 4.58]; N: 2; I²: 18%). Insufficient trials reported on pain outcomes. Two trials demonstrated reduced 1-year injury incidence following gait retraining.

CONCLUSIONS

Gait retraining interventions altered step rate and knee kinematics, lowered vertical loading rates, and did not affect running performance. J Orthop Sports Phys Ther 2022;52(4):192-206. Epub 05 Feb 2022. doi:10.2519/jospt.2022.10585.

Factors Affecting Training and Physical Performance in Recreational Endurance Runners

Endurance running has become an immensely popular sporting activity, with millions of recreational runners around the world. Despite the great popularity of endurance running as a recreational activity during leisure time, there is no consensus on the best practice for recreational runners to effectively train to reach their individual objectives and improve physical performance in a healthy manner. Moreover, there are lots of anecdotal data without scientific support, while most scientific evidence on endurance running was developed from studies observing both recreational and professional athletes of different levels. Further, the transference of all this information to only recreational runners is difficult due to differences in the genetic predisposition for endurance running, the time available for training, and physical, psychological, and physiological characteristics. Therefore, the aim of this review is to present a selection of scientific evidence regarding endurance running to provide training guidelines to be used by recreational runners and their coaches. The review will focus on some key aspects of the training process, such as periodization, training methods and monitoring, performance prediction, running technique, and prevention and management of injuries associated with endurance running.

Real-time feedback by wearables in running: Current approaches, challenges and suggestions for improvements

Injuries and lack of motivation are common reasons for discontinuation of running. Real-time feedback from wearables can reduce discontinuation by reducing injury risk and improving performance and motivation. There are however several limitations and challenges with current real-time feedback approaches. We discuss these limitations and challenges and provide a framework to optimise real-time feedback for reducing injury risk and improving performance and motivation. We first discuss the reasons why individuals run and propose that feedback targeted to these reasons can improve motivation and compliance. Secondly, we review the association of running technique and running workload with injuries and performance and we elaborate how real-time feedback on running technique and workload can be applied to reduce injury risk and improve performance and motivation. We also review different feedback modalities and motor learning feedback strategies and their application to real-time feedback. Briefly, the most effective feedback modality and frequency differ between variables and individuals, but a combination of modalities and mixture of real-time and delayed feedback is most effective. Moreover, feedback promoting perceived competence, autonomy and an external focus can improve motivation, learning and performance. Although the focus is on wearables, the challenges and practical applications are also relevant for laboratory-based gait retraining.

Validity of a novel method to measure vertical oscillation during running using a depth camera

Recent advancements in low-cost depth cameras may provide a clinically accessible alternative to conventional three-dimensional (3D) multi-camera motion capture systems for gait analysis. However, there remains a lack of information on the validity of clinically relevant running gait parameters such as vertical oscillation (VO). The purpose of this study was to assess the validity of measures of VO during running gait using raw depth data, in comparison to a 3D multi-camera motion capture system. Sixteen healthy adults ran on a treadmill at a standard speed of 2.7 m/s. The VO of their running gait was simultaneously collected from raw depth data (Microsoft Kinect v2) and 3D marker data (Vicon multi-camera motion capture system). The agreement between the VO measures obtained from the two systems was assessed using a Bland-Altman plot with 95% limits of agreement (LOA), a Pearson's correlation coefficient (r), and a Lin's concordance correlation coefficient (r_c). The depth data from the Kinect v2 demonstrated excellent results across all measures of validity (r = 0.97; r_c = 0.97; 95% LOA = -8.0 mm - 8.7 mm), with an average absolute error and percent error of 3.7 (2.1) mm and 4.0 (2.0)%, respectively. The findings of this study have demonstrated the ability of a low cost depth camera and a novel tracking method to accurately measure VO in running gait.

Small Step Frequency Changes Due to Footwear Condition Have No Effect on Running Economy

The aim of this study is to examine if small increases to step frequency associated with minimal footwear can influence Running Economy (RE). Twelve club-level runners with eight weeks of minimal footwear experience were recruited (age, 41±9 years; stature, 177.2±10.4 cm; body mass, 72.6±10.2 kg; V˙O _2max , 52.1±7.5 mL·min ^-1 ·kg ^-1 ). Two 6-min RE tests, one in minimal footwear and one in conventional running shoes were performed at 11 km·h ^-1 . Two more 6-min tests were completed during which step frequency was controlled using a metronome at the cadence of the opposite footwear condition (RE _revSF ). Comparisons were completed between the same footwear using repeated measures ANCOVA. The increase in step frequency for minimal footwear vs. conventional running shoes was 7.3±2.3 steps per minute (3.9% difference; 95% CI of difference [5.87 to 8.80 steps/min]; p≤0.001; Cohen's d=0.70). No significant differences were identified between RE and RE _revSF for minimal footwear (40.72±4.08 vs. 41.09±4.19 mL·min ^-1 ·kg ^-1 ; 95% CI of difference [-1.71 to 0.97]; p=0.55; Cohen's d=0.09), or conventional running shoes (42.04±4.68 vs. 41.74±5.09 mL·min ^-1 ·kg ^-1 ; 95% CI of difference [-0.78 to 1.37]; p=0.55; Cohen's d=0.06). Small changes in step frequency (~4%) did not have any significant impact on RE.

Perspectives on walking from people with multiple sclerosis and reactions to video self-observation

Purpose: People with multiple sclerosis (MS) rank walking among the most challenging aspects of their condition. A greater understanding of people's perspectives concerning their walking may help to prioritize walking outcomes and strategies for optimizing walking. The purpose was to explore perceptions of walking in people with MS and to describe their reactions after observing themselves walk on video.Materials and methods: An interpretive thematic analysis study using face-to-face, semi-structured interviews was conducted with 14 people who self-identified a change in their walking due to MS. Participants were video-recorded walking and watched their video during the interview.Results: Four themes were identified: "awareness," "acceptance," "constant change," and "increased effort." People with MS develop awareness of how their walking performance looks and awareness of constantly-changing internal factors and external factors which impact their walking. Awareness of change in fatigue, temperature, terrain, and the use of aids in particular are perceived relevant to walking and to impact the effort required to walk. People with MS also describe differences in their acceptance of how others view their walking and the changes related to walking. An analogy with a marionette performing describes how people perceive walking as no longer automatic; instead walking requires the person to consciously pull the strings to walk. An increase in both the physical and cognitive effort is required to walk and an awareness and acceptance of a variety of changes in oneself and the lived world may help or hinder walking. People with MS are willing to watch themselves walk on video and are not surprised by what they observe.Conclusions: People with MS develop a learned self-awareness with variable levels of acceptance about their walking function and what it looks like. The perceptions on walking from persons with MS suggest that focusing on reducing the effort to walk and minimizing the constantly-changing variables may help to optimize walking.Implications for rehabilitationPeople with multiple sclerosis are challenged by the increased effort and constant change required to walk in their day-to-day lives.A focus on minimizing both the effort to walk and the changing variables (i.e., fluctuating symptoms and environmental factors) is warranted.People with multiple sclerosis develop a learned awareness of how they walk and how their walking looks.Acceptance of loss of walking function is variable.Video self-observation is a feasible tool which warrants further exploration for enhancing acceptance of walking function and accommodating strategies.

Positive Effects of Augmented Feedback to Reduce Time on Ground in Well-Trained Runners

CONTEXT

Successful elite sprint to long-distance runners are known to have shorter ground-contact time (GCT) than their less successful counterparts.

PURPOSE

To investigate whether augmented feedback (aF) about GCT can reduce the time on ground (TOG) per minute in long-distance runners and, if so, whether this reduction improves running performance.

METHODS

Thirty well-trained runners were allocated to 3 groups. The intervention group (IG) received visual aF about their GCT during 8 high-intensity interval sessions in the 4-wk training period and were instructed to minimize GCT. The 1st control group (CG1) trained with the IG but was not given any feedback. The 2nd control group (CG2) followed their own training routine. Data were obtained pre- and postintervention for all 3 groups. The dependent variable was TOG per minute, computed from step frequency and GCT.

RESULTS

The IG significantly reduced TOG (P = .043, -1.7%, 90%CL -3.1;-0.3) and improved their mean 10 × 400-m performance time (P < .001, -1.5%, 90%CL -1.9;-1.1). In contrast, the 2 control groups revealed unchanged values, indicating that normal high-intensity training and an individualized routine without aF were not able to reduce TOG. The fact that CG1 received the same instructions and participated in the same training sessions as the IG underlined that aF was crucial to reduce TOG.

CONCLUSIONS

The provision of aF about GCT seems to be a promising approach that should be considered during training practice of well-trained runners.

Visual knee-kinetic biofeedback technique normalizes gait abnormalities during high-demand mobility after total knee arthroplasty

BACKGROUND

Abnormal knee mechanics frequently follow total knee arthroplasty (TKA) surgery with these deficits amplifying as task demands increase. Knee-kinetic biofeedback could provide a means of attenuating gait abnormalities. The purposes of this study were as follows: (1) to describe the gait characteristic differences between patients with TKA and non-TKA adults during level (low-demand) and decline (high-demand) walking; and (2) where differences existed, to determine the impact of knee-kinetic biofeedback on normalizing these abnormalities.

METHODS

Twenty participants six months following a primary TKA and 15 non-TKA peers underwent gait analysis testing during level and decline walking. Knee-kinetic biofeedback was implemented to patients with TKA to correct abnormal gait characteristics if observed.

RESULTS

Patients with TKA had lower knee extensor angular impulse (p<0.001), vGRF (p=0.001) and knee flexion motion (p=0.005) compared to the non-TKA group during decline walking without biofeedback. Patients with TKA normalized their knee extensor angular impulse (p=0.991) and peak vGRF (p=0.299) during decline walking when exposed to biofeedback. No between-group differences were observed during level walking. Groups were similar in age, gender, body mass index, physical activity level, pain interference and depression scores (p>0.05).

CONCLUSION

Patients with TKA demonstrate abnormal gait characteristics during a high-demand walking task when compared to non-TKA peers. Our findings indicate that knee-kinetic biofeedback can induce immediate improvements in gait characteristics during a high-demand walking task. There may be a potential role for the use of visual knee-kinetic biofeedback techniques to improve gait abnormalities during high-demand tasks following TKA.

Kinematics and metabolic cost of running on an irregular treadmill surface

The purpose of this study was to investigate the kinematic and metabolic effects of running on an irregular surface. We also examined how altering the frontal plane foot angle (inversion/eversion) at contact using real-time visual feedback would affect these other variables. Sixteen participants completed three running bouts lasting 5-7 minutes each on an irregular surface (IS) treadmill, a traditional smooth surface (SS) treadmill, and on SS while receiving visual feedback of the frontal plane foot angle at contact (SSF) with a goal of matching IS foot angle on SS. Frontal plane foot angle increased 40% from IS to SS (IS: 8.4 ± 4.09°, SS: 11.8 ± 4.52°, P < 0.0001, ES 1.40). Knee flexion angle at contact decreased 33% from IS to SS (IS: 9.2 ± 4.88°, SS: 6.2 ± 5.03°, P < 0.0001, ES 1.30). Rate of oxygen consumption decreased by 10% from IS to SS (IS: 37.9 ± 5.68 ml·kg^-1·min^-1, SS: 34.1 ± 5.07 ml·kg^-1·min^-1, P < 0.0001, ES 3.05). PSD of leg accelerations decreased by 38% (IS: 0.17 ± 0.07 g²/Hz, SS: 0.106 ± 0.05 g²/Hz, P < 0.000, ES 1.69). Frontal plane foot angle decreased by 14% from SS to SSF (SS: 11.8 ± 4.52°, SSF: 10.1 ± 4.42°, P = 0.027. ES 0.62) but did not result in significant changes in any other variables. There were no significant differences in shock attenuation between any conditions (IS: -9.8 ± 2.26 dB, SS: -9.5 ± 3.12 dB, SSF: -9.9 ± 2.62 dB, P = 0.671). Running with greater eversion on the irregular surface may be an attempt by runners to reduce the perceived potential of an inversion ankle sprain. As a partial compensation for the decreased foot angle, runners increased knee flexion. This maintained shock attenuation but increased the rate of oxygen consumption. Altering the foot angle at contact using feedback on the SS caused the knee angle at contact to increase, but did not change shock attenuation or metabolic cost.

Is There an Economical Running Technique? A Review of Modifiable Biomechanical Factors Affecting Running Economy

Running economy (RE) has a strong relationship with running performance, and modifiable running biomechanics are a determining factor of RE. The purposes of this review were to (1) examine the intrinsic and extrinsic modifiable biomechanical factors affecting RE; (2) assess training-induced changes in RE and running biomechanics; (3) evaluate whether an economical running technique can be recommended and; (4) discuss potential areas for future research. Based on current evidence, the intrinsic factors that appeared beneficial for RE were using a preferred stride length range, which allows for stride length deviations up to 3 % shorter than preferred stride length; lower vertical oscillation; greater leg stiffness; low lower limb moment of inertia; less leg extension at toe-off; larger stride angles; alignment of the ground reaction force and leg axis during propulsion; maintaining arm swing; low thigh antagonist–agonist muscular coactivation; and low activation of lower limb muscles during propulsion. Extrinsic factors associated with a better RE were a firm, compliant shoe–surface interaction and being barefoot or wearing lightweight shoes. Several other modifiable biomechanical factors presented inconsistent relationships with RE. Running biomechanics during ground contact appeared to play an important role, specifically those during propulsion. Therefore, this phase has the strongest direct links with RE. Recurring methodological problems exist within the literature, such as cross-comparisons, assessing variables in isolation, and acute to short-term interventions. Therefore, recommending a general economical running technique should be approached with caution. Future work should focus on interdisciplinary longitudinal investigations combining RE, kinematics, kinetics, and neuromuscular and anatomical aspects, as well as applying a synergistic approach to understanding the role of kinetics.

Gait Retraining: Altering the Fingerprint of Gait

In terms of running, there is evidence that links mechanics with injury. This evidence provides the justification for altering these mechanics. Increased hip adduction and vertical impact loading have been most commonly associated with injury. More work is needed in order to understand the optimal way to retrain gait patterns in runners. The human body has a considerable ability to adapt. To provide individuals with the ability to alter faulty movement patterns in ways that can reduce injury risk is a powerful tool.

Gait Retraining for Injured and Healthy Runners Using Augmented Feedback: A Systematic Literature Review

STUDY DESIGN

Systematic literature review.

OBJECTIVES

This review sought to determine the efficacy of real-time visual and/or auditory feedback for modifying kinematics and kinetics during running gait.

BACKGROUND

Real-time visual and auditory feedback has gained popularity in the clinical and research settings. Rehabilitation time and injury prevention may be improved when clinicians are able to modify running mechanics in a patient population.

METHODS

A thorough search of PubMed, CINAHL, and Web of Science from 1989 to January 2015 was performed. The search sought articles that examined real-time visual or auditory feedback for the purposes of modifying kinematics or kinetics in injured or healthy runners. Study design and methodological quality were rated using a 20-point scale.

RESULTS

Ten studies were identified for inclusion in the review, 2 of high and 8 of moderate methodological quality. There was a consensus in the literature that the use of real-time feedback is effective in reducing variables related to ground reaction forces, as well as in positively modifying previously identified risky lower extremity kinematic movement patterns in healthy runners and those with patellofemoral pain and chronic exertional compartment syndrome. No one method of feedback was identified as being superior. Mirror and 2-dimensional video feedback were identified as potential methods for running-gait modification in a clinical setting.

CONCLUSION

In conjunction with traditional therapeutic interventions, real-time auditory and visual feedback should be considered for treating injured runners or addressing potentially injurious running mechanics in a healthy population.

Eight weeks gait retraining in minimalist footwear has no effect on running economy

PURPOSE

To evaluate the effects of an eight week combined minimalist footwear (MFW) and gait-retraining intervention on running economy (RE) and kinematics in conventional footwear runners.

METHODS

Twenty-three trained male runners (age: 43 ± 10 years, stature: 177.2 ± 9.2 cm, body mass: 72.8 ± 10.2 kg, V̇O2max: 56.5 ± 7.0 mL min(-1) kg(-1)) were recruited. Participants were assigned to either an intervention group (n = 13) who gradually increased exposure to MFW and also implemented gait-retraining over an eight week period. RE and kinematics were measured in both MFW and conventional running shoes (CRS) at pre-tests and eight weeks, in a random order. In contrast the control group (n = 10) had no MFW exposure or gait retraining and were only tested in CRS.

RESULTS

The MFW and gait re-training intervention had no effect on RE (p < .001). However, RE was significantly better in MFW (mean difference 2.72%; p = .002) at both pre and post-tests compared to CRS. Step frequency increased as a result of the intervention (+5.7 steps per minute [spm]; p < .001), and was also significantly higher in MFW vs. CRS (+7.5 spm; p < .001).

CONCLUSION

Whilst a better RE in MFW was observed when compared to CRS due to shoe mass, familiarization to MFW with gait-retraining was not found to influence RE.

Influence of tibial shock feedback training on impact loading and running economy

PURPOSE

The purpose of this study was to determine whether real-time feedback (RTF) training would reduce impact loading variables previously linked with tibial stress fracture risk and whether these adaptations would influence running economy.

METHODS

Twenty-two male runners were randomly assigned to RTF (n = 12) and control (n = 10) groups. The RTF group received feedback based on their peak tibial axial accelerations (PTA) during six 20-min treadmill runs for 3 wk, whereas the control group adhered to the same training but without feedback. Unilateral three-dimensional kinematic and kinetic analysis and running economy measurements were conducted before, after, and at 1 month posttraining.

RESULTS

The RTF group had significant reductions (P < 0.01) in PTA and average and instantaneous vertical force loading rates after training as compared with no changes in the control group. These modifications in impact loads were only maintained in PTA 1 month after the training. A significant increase (P = 0.0033) in ankle plantarflexion at initial contact and a significant change (P = 0.030) in foot strike pattern from a rearfoot to midfoot strike pattern and a significant decrease (P = 0.008) in heel vertical velocity at initial contact appeared to be the primary mechanical strategies adopted by runners to reduce impact loading after RTF training. Despite these gait adaptations, running economy was unaffected.

CONCLUSIONS

The results of this study suggest that gait retraining using RTF is an effective means of eliciting reductions in impact loading without negatively affecting running economy. However, with loading rate reductions not being maintained 1 month posttraining, further research is required to determine how these reductions in impact severity can be retained long term.

Rehabilitation of the patellofemoral joint

Nonsurgical care by a specialist in physical medicine and rehabilitation is typically a multifaceted approach, which can include modalities, bracing, medication, injection, proprioceptive techniques, restoration of normal movement patterns, and overall conditioning. There is evidence that physical therapy interventions have significant beneficial effect on pain and function compared with no treatment.

Lower-leg compression, running mechanics, and economy in trained distance runners

The efficacy of and mechanisms behind the widespread use of lower-leg compression as an ergogenic aid to improve running performance are unknown. The purpose of this study was to examine whether wearing graduated lower-leg compression sleeves during exercise evokes changes in running economy (RE), perhaps due to altered gait mechanics. Sixteen highly trained male distance runners completed 2 separate RE tests during a single laboratory session, including a randomized-treatment trial of graduated calf-compression sleeves (CS; 15-20 mm Hg) and a control trial (CON) without compression sleeves. RE was determined by measuring oxygen consumption at 3 constant submaximal speeds of 233, 268, and 300 m/min on a treadmill. Running mechanics were measured during the last 30 s of each 4-min stage of the RE test via wireless triaxial 10-g accelerometer devices attached to the top of each shoe. Ground-contact time, swing time, step frequency, and step length were determined from accelerometric output corresponding to foot-strike and toe-off events. Gait variability was calculated as the standard deviation of a given gait variable for an individual during the last 30 s of each stage. There were no differences in VO2 or kinematic variables between CON and CS trials at any of the speeds. Wearing lower-leg compression does not alter the energetics of running at submaximal speeds through changes in running mechanics or other means. However, it appears that the individual response to wearing lower-leg compression varies greatly and warrants further examination.

Mechanisms for improved running economy in beginner runners

Controversy surrounds whether running mechanics make good predictors of running economy (RE) with little known about the development of an economical running gait.

PURPOSE

The aim of this study was to identify if mechanical or physiological variables changed during 10 wk of running in beginners and whether these changes could account for any change in RE.

METHODS

A 10-wk running program (10 wkRP) was completed by 10 female beginner runners. A bilateral three-dimensional kinematic and kinetic analysis, in addition to RE and lower body flexibility measurements, was performed before and after the 10 wkRP. The Balke-Ware graded walking exercise test was performed before and after the 10 wkRP to determine VO2max.

RESULTS

Seven kinematic and kinetic variables significantly changed from before to after training, in addition to a significant decrease in calf flexibility (27.3° ± 6.3° vs 23.9° ± 5.6°, P < 0.05). A significant improvement was seen in RE (224 ± 24 vs 205 ± 27 mL · kg(-1) · km(-1), P < 0.05) and treadmill time to exhaustion (16.4 ± 3.2 vs 17.3 ± 2.8 min, P < 0.05); however, VO2max remained unchanged from before to after training (34.7 ± 5.1 vs 34.3 ± 5.6 mL · kg(-1) · min(-1)). Stepwise regression analysis showed three kinematic variables to explain 94.3% of the variance in change in RE. They were a less extended knee at toe off (P = 0.004), peak dorsiflexion occurring later in stance (P = 0.001), and a slower eversion velocity at touchdown (P = 0.042). The magnitude of change for each variable was 1.5%, 4.7%, and 34.1%, respectively.

CONCLUSIONS

These results show that beginner runners naturally developed their running gait as they became more economical runners.

Gait retraining to reduce lower extremity loading in runners

BACKGROUND

tibial stress fractures, which are among the most common running related injuries, have been associated with increased lower extremity loading (i.e., peak positive acceleration of the tibia, vertical force impact peak, and average and instantaneous vertical force loading rates) during initial contact. This study was conducted to evaluate the efficacy of a gait retraining program designed to reduce this loading during running and to assess the short-term persistence of these reductions.

METHODS

ten runners (six females and four males) with peak positive tibial acceleration greater than 8g, measured in an initial screening, participated in the retraining program. During the retraining sessions, subjects ran on a treadmill and received real-time visual feedback from an accelerometer attached to their distal tibias. Tibial acceleration and vertical ground reaction force data were collected from subjects during overground data collection sessions held pre-training, post-training, and at a 1-month follow-up.

FINDINGS

peak positive acceleration of the tibia, vertical force impact peak, and average and instantaneous vertical force loading rates were all reduced immediately following the gait retraining. The decrease in tibial acceleration was nearly 50%. The reductions in vertical force loading rates and vertical force impact peak were approximately 30% and 20%, respectively. These reductions were maintained at the 1-month follow-up.

INTERPRETATION

subjects were able to run with reduced tibial acceleration and vertical force loading immediately following completion of the gait retraining program and at the 1-month follow-up evaluation. This may reduce their risk of stress fractures.

Reducing impact loading during running with the use of real-time visual feedback

STUDY DESIGN

Single-subject with repeated measures.

OBJECTIVES

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.

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Twenty-five years of psychology in the Journal of Sports Sciences: a historical overview

We provide an overview of some of the outstanding papers published in the Journal over the last 25 years within the discipline of psychology. Altogether, almost 300 papers had been published in the Journal under the psychology banner at the start of its silver anniversary year. The greatest contribution of papers has come from the motor control and learning and sport psychology sub-areas, with papers focusing on exercise psychology being a more recent addition. Prominent research themes that have emerged from each of the different sub-areas are reviewed and some notable omissions highlighted. Finally, some issues for sport and exercise psychologists to consider in coming years are briefly highlighted.

A Multidisciplinary Approach to the Evaluation, Reconstruction and Rehabilitation of the Multi-Ligament Injured Athlete

Knee dislocations with multi-ligamentous involvement are potentially limb-threatening injuries that require extensive surgical and rehabilitative intervention. These knee injuries, such as combined anterior cruciate ligament, posterior cruciate ligament, medial collateral ligament and/or lateral collateral ligament injuries, are devastating injuries with results that vary from total disability to nearly full recovery of function. Recent surgical advances, including the use of allograft tissues, have increased the efficacy of these procedures while posing new challenges. By combining scientifically based surgical and rehabilitative approaches, improved outcomes in these difficult cases are being reported in the orthopaedic literature. This review details the epidemiology and biomechanics of these serious knee ligament injuries. In addition, state-of-the-art surgical and rehabilitative techniques will be outlined. Clinical and diagnostic imaging evaluation of these knee injuries is reviewed in order to plan and execute the surgical and rehabilitative practices. We review the basic science, surgical and rehabilitative theories and practices associated with bringing patients with these serious knee injury injuries to full recovery, and detail the development of strategies for developing protocols to address these complicated cases.

Rehabilitation after anterior cruciate ligament reconstruction: criteria-based progression through the return-to-sport phase

Rehabilitation following anterior cruciate ligament (ACL) reconstruction has undergone a relatively rapid and global evolution over the past 25 years. However, there is an absence of standardized, objective criteria to accurately assess an athlete's ability to progress through the end stages of rehabilitation and safe return to sport. Return-to-sport rehabilitation, progressed by quantitatively measured functional goals, may improve the athlete's integration back into sport participation. The purpose of the following clinical commentary is to introduce an example of a criteria-driven algorithm for progression through return-to-sport rehabilitation following ACL reconstruction. Our criteria-based protocol incorporates a dynamic assessment of baseline limb strength, patient-reported outcomes, functional knee stability, bilateral limb symmetry with functional tasks, postural control, power, endurance, agility, and technique with sport-specific tasks. Although this algorithm has limitations, it serves as a foundation to expand future evidence-based evaluation and to foster critical investigation into the development of objective measures to accurately determine readiness to safely return to sport following injury.

The effect of training on running economy and performance in recreational athletes

PURPOSE

To analyze the effect of an 8-wk training program on the energy cost of running (C) and the performance of 16 recreational males.

METHODS

A training group (TG, N = 8, 25.3 +/- 2.9 yr, 183.6 +/- 7.3 cm, 80.9 +/- 9.6 kg) and a control group (CG, N = 8, 24.3 +/- 3.7 yr, 179.3 +/- 6.1 cm, 75.5 +/- 8.0 kg) performed three two-stage tests (TST) at weeks 0, 4, and 8 (W0, W4, W8). Speeds of the first (v-slow) and second stage (v-fast) were 2.4 +/- 0.3 vs 2.5 +/- 0.4 m x s(-1) and 3.7 +/- 0.3 vs 3.9 +/- 0.4 m.s (TG vs CG), respectively. Maximum running time at v-fast (T) served as the measure of performance. C was calculated from oxygen uptake above rest, blood lactate concentration, and speed. The TG trained 3-5x wk(-1) at an HR of +/-10 beats of the HR measured at v-slow at W0 (161 +/- 12 bpm). The CG did not train.

RESULTS

At W0, there were no significant differences between the groups in T (377 +/- 47 vs 335 +/- 34 s) and C (v-slow: 4.1 +/- 0.3 vs 4.3 +/- 0.4 J x kg(-1) x m(-1); v-fast: 4.2 +/- 0.4 vs 4.0 +/- 0.4 J x kg(-1) x m(-1)). In the CG, T and C remained almost unchanged at W4 (363 +/- 38 s, 4.0 +/- 0.4 J x kg(-1) x m(-1)) and at W8 (342 +/- 49 s, 4.0 +/- 0.3 J x kg(-1) x m(-1)). In the TG, T increased (P < 0.05) at W4 (469 +/- 45 s) and at W8 (591 +/- 109 s). At v-fast, also C increased (P < 0.05) at W8 (4.6 +/- 0.4 J x kg(-1) x m(-1)), whereas at v-slow, C decreased (P < 0.05) at W4 (3.7 +/- 0.4 J x kg(-1) x m(-1)) with no further change at W8 (3.7 +/- 0.4 J x kg(-1) x m(-1)).

CONCLUSION

The training successfully increased running performance in terms of T. During the initial training period, C could be reduced at the speed predominantly used in training. However, at high running speeds, C may even increase if the corresponding running time is largely increased.

Reduced eccentric loading of the knee with the pose running method

PURPOSE

The aim of this study was to compare the biomechanical changes during natural heel-toe running with learned midfoot and Pose running.

METHODS

Twenty heel-toe runners were instructed in midfoot running and a novel running style in which the acromium, greater trochanter, and lateral malleolus are aligned in stance (Pose running). Clinical gait analysis was performed for each running style and the biomechanical variables compared.

RESULTS

In comparison with midfoot and heel-toe running Pose running was characterized by shorter stride lengths and smaller vertical oscillations of the sacrum and left heel marker. Compared with midfoot and Pose running heel-toe running was characterized by greater magnitudes and loading rates of the vertical impact force. In preparation for initial contact, the knee flexed more in Pose than in heel-toe and midfoot running. The ankle at initial contact was neutral in Pose compared with a dorsiflexed and plantarflexed position in heel-toe and midfoot running, respectively. The knee power absorption and eccentric work were significant lower (P < 0.05) in Pose than in either heel-toe or midfoot running. In contrast, there was a higher power absorption and eccentric work at the ankle in Pose compared with heel-toe and midfoot running.

CONCLUSIONS

Pose running was associated with shorter stride lengths, smaller vertical oscillations of the sacrum and left heel markers, a neutral ankle joint at initial contact, and lower eccentric work and power absorption at the knee than occurred in either midfoot or heel-toe running. The possibility that such gait differences could be associated with different types and frequencies of running injuries should be evaluated in controlled clinical trails.

Current issues in the mechanics of athletic activities. A position paper

This position paper reviews current research topics in the study of athletic activities, which biomechanists would consider to be important or contentious issues, and focuses on critically evaluating what needs to be done in future research. It concludes that there remain many unresolved issues in the mechanics of athletic activities, many of which overlap with other disciplines. These issues relate to injury mechanisms, the control and co-ordination of movement, and ways of providing biomechanical feedback to enhance performance in athletic activities. Research to address these important issues will increasingly become more question than discipline orientated, must focus more on mechanisms than description, and will involve teams of researchers interacting on interdisciplinary problems.

Short-term changes in 10-km race pace aerobic demand and gait mechanics following a bout of high-intensity distance running

Following treadmill accommodation and a 3-day period of tapered running, ten well-trained male distance runners [x maximum oxygen uptake (VO2max) = 71.3 ml.kg-1.min-1] performed two 10-min level treadmill runs designed to assess running economy at 90% VO2max. Video recordings were obtained during the last minute of each run to quantify selected gait descriptors. Two to 3 days following the second economy run, each subject completed 30 min of high-intensity (HI) running at 90% VO2max. One 2, and 4 days after the HI run, subjects repeated the 10-min economy runs. Compared to pre HI-run values, no significant change (P > 0.05) in running economy was observed during the post-HI runs. Biomechanical analyses also revealed that running style remained unaltered after the HI run. These results support earlier findings obtained on moderately trained subjects featuring measurement of running economy and gait mechanics at less-demanding intensities and suggest that among well-trained athletes, 30 min of HI running does not elicit an increase in VO2 or disrupt gait mechanics over the short term in subsequent distance runs performed at near-maximal speeds.