Running-specific Prostheses Research Articles

Biomechanics of Running-Specific Prosthesis and Athletes Supports

Biomechanics of Running-Specific Prosthesis and Athletes Supports

Effects of prosthetic stiffness and added mass on metabolic power and asymmetry in female runners with a leg amputation.

Similar to nonamputees, female athletes with unilateral transtibial amputation (TTA) using running-specific leg prostheses (RSPs) may have worse running economy and higher rates of running-related injury than male athletes. Optimizing RSP configuration for female athletes could improve running economy and minimize biomechanical asymmetry, which has been associated with running-related injury. Nine females with a TTA ran at 2.5 m/s while we measured metabolic rates and ground reaction forces. Subjects used an RSP with a manufacturer-recommended stiffness category, one category less stiff and two categories less stiff than recommended. Use of an RSP two categories less stiff resulted in 3.0% lower net metabolic power (P = 0.04), 7.8% lower affected leg stiffness (P = 6.01 × 10-4), increased contact time asymmetry (P = 0.04), and decreased stance average vertical ground reaction force asymmetry (P = 0.04) compared with a recommended stiffness category RSP. Lower RSP stiffness (kN/m) values were associated with lower net metabolic power (P = 0.02), lower affected leg stiffness (P = 1.36 × 10-4), longer affected leg contact time (P = 1.46 × 10-4), and similar affected leg peak and stance-average vertical ground reaction force compared with higher RSP stiffness values. Subjects then used the RSP stiffness category that elicited the lowest net metabolic power with 100 g, 200 g, and 300 g added distally. We found no significant effects of added mass on net metabolic power, biomechanics, or asymmetry. These results suggest that female runners with a TTA could decrease metabolic power during running while minimizing biomechanical asymmetries, which have been associated with running-related injury, by using an RSP two categories less stiff than manufacturer recommended.NEW & NOTEWORTHY Females with unilateral transtibial amputation can improve running performance through reductions in net metabolic power by using a running-specific prosthesis (RSP) that is less stiff than manufacturer-recommended. Lower RSP stiffness values are associated with greater leg stiffness and contact time asymmetry, and lower stance-average vertical ground reaction force asymmetry. However, we found that adding mass to the RSP did not affect net metabolic power and stance-phase biomechanical asymmetries during running.

A review of evidence on mechanical properties of running specific prostheses and their relationship with running performance.

Although mechanical properties of running specific prostheses (RSPs) can affect running performance, manufacturers do not consistently report them. This study aimed to review existing literature on RSP mechanical and structural properties and their relationship with running performance. A comprehensive search was conducted using keywords related to mechanical properties of RSPs and running performance. Search terms included stiffness and hysteresis, as well as performance outcomes including metabolic cost and running speed. Non-peer-reviewed and non-English publications were excluded. Twenty articles were included in the review. Sixteen studies used a material testing machine to measure RSP material properties, and four articles used other techniques including 2D/3D video capture and force platforms. Both measurement techniques and reporting of outcomes were inconsistent, which limits the ability to draw broad conclusions. Additionally, several studies did not report the numerical data for material properties despite measuring them. Relatively few articles measured both material properties and running performance and assessed correlations. Several articles connected prosthesis properties to running performance. However, inconsistent measurement and reporting of mechanical properties, along with the multifactorial nature of the athlete-prosthesis system, limit the ability to draw broad conclusions regarding the relationship between material and structural properties and athlete performance. Current evidence may be useful for clinicians seeking ways to optimize RSP stiffness in a case-by-case basis; however, clinicians would benefit from more consistent and systematic comparisons of the attributes of different RSPs and their role in performance.

Running-specific prosthesis' performance characterization by dynamic finite element approach.

Composite running-specific prostheses (RSP) are widely used by athletes with lower limb amputations to simulate the spring-like behavior of biological legs. However, the effect of these devices on the biomechanics of athletes with transtibial amputations remains uncertain. To address this issue, this study proposes a time-dependent finite element model that uses angles and dynamic loads during ground contact to evaluate RSP performance parameters such as stiffness and energy efficiency. The study also examines the impact of running speed and RSP geometry on performance. The in-silico characterization approach used in this study takes into account both the intrinsic characteristics of the RSP and the athlete's biomechanics to identify the influence of fundamental geometric variables of the RSP on performance. The model is verified by comparing its results with experimental data. The study found that as running speed increases, RSP stiffness, vertical ground reaction force (vGRF), and contact time decrease. The force-displacement profiles of RSP are nonlinear, but a linear function can be used to accurately represent their behavior at high sprinting speeds. Using higher RSP reduces energy efficiency and vGRF due to their lower stiffness. J-curve RSP result in higher stiffness, vGRF, and strain energy, while C-curve RSP are associated with longer contact times and higher energy efficiency.

A digital process to replicate the socket-foot alignment in below-knee running specific prostheses

A well-fitting socket and a fine-tuned foot alignment are crucial elements in a running-specific prosthesis to allow Paralympic athletes with below-knee amputation to express their full competitive potential. For this reason, once a satisfactory socket-foot configuration is established after dynamic alignment, it is fundamental to reproduce the same conditions when constructing the definitive carbon fiber socket, and when renewing or constructing a back-up prosthesis, without dismantling the original. In addition, to cope with emerging needs of the athlete, it would be beneficial to implement fine-tuning adjustments of the alignment in a very controlled manner. At present, this requires elaborate bench procedures, which tend to be expensive, time consuming, prone to manual errors, cumbersome in use and most often require damaging or disposing of the current socket. In this study, we propose an original CAD/CAM workflow that allows replicating the desired socket-foot configuration for below-knee sprinting prostheses, as well as performing socket adaptations and introducing fine-tuning adjustments to the alignments. The workflow is exemplified with reference to two case studies involving elite Paralympic runners with transtibial and partial foot amputations, respectively.

Running-Specific Prosthesis

Sports help children “develop physical skills that contribute to a lifetime of physical involvement; … learn social and emotional skills; develop moral values; and acquire a better sense of self through increased perceived competence, self-esteem, and self-confidence” (Ewing, Gano-Overway, Branta, & Seefeldt, 2002). Lower-leg amputations jeopardize children’s ability to continue participating in sports, as it removes a part of the body that is essential for running and sports participation. Running-specific prostheses (RSPs), a type of lower-limb prosthesis, provide a solution to this issue. Compared to daily-use prosthetics, running-specific prosthetics have a higher energy-storage capacity, are more flexible, and are more springy, allowing them to mimic the nature of running biological legs better than daily-use prosthetics. RSPs also have customizations that are specific to the physical traits and activity of an amputee, allowing an amputee to play a plethora of sports. Although children must overcome challenges regarding the change in biomechanics while running with an RSP and accounting for the rapid growth of children, RSPs can provide amputees the opportunity to return to the sports environment.

Sprinting with bilateral transtibial running-specific prostheses versus biological limbs - are they comparable? Comments on Beck et al. (2022).

Since publication of this paper (Royal Society open science, 2022. 9(1): p. 211799), the authors have published a correction clarifying that the paper presents a case study that '… did not meet the definition for research with regard to human subjects'. The data are incorrectly referred to as experimental because the study has no experimental control. Furthermore, the paper has been presented previously but the version presented here selectively omits several analyses, posing a significant risk of bias. Of the prosthetic-related disadvantages identified by the authors, the most substantive was a 40% increase in time to 20 m (59.5 s.d. below the mean for NA sprinters). However the analysis was incomplete: acceleration modelling for NA sprinters continued up to 98% of maximum velocity, while Fastest BA was truncated at approximately 80%. We extrapolated the model, revealing the duration of maximum acceleration for Fastest BA is approximately 100% longer than NA sprinters. Important differences in Fastest BA contact lengths (0.10-0.15 m) were also identified. We posit that together, these large and important differences in sprint biomechanics and their likely physiological consequences suggest that running with and without prosthetics are so different that, although running times may be similar, the precautionary principle should apply and, in the interests of athletic competition integrity, runners with and without prosthetics should continue to compete separately.

Equivalent running leg lengths require prosthetic legs to be longer than biological legs during standing

We aimed to determine a method for prescribing a standing prosthetic leg length (ProsL) that results in an equivalent running biological leg length (BioL) for athletes with unilateral (UTTA) and bilateral transtibial amputations (BTTA). We measured standing leg length of ten non-amputee (NA) athletes, ten athletes with UTTA, and five athletes with BTTA. All athletes performed treadmill running trials from 3 m/s to their maximum speed. We calculated standing and running BioL and ProsL lengths and assessed the running-to-standing leg length ratio (Lratio) at three instances during ground contact: touchdown, mid-stance, and take-off. Athletes with UTTA had 2.4 cm longer standing ProsL than BioL length (p = 0.030), but their ProsL length were up to 3.3 cm shorter at touchdown and 4.1 cm shorter at mid-stance than BioL, at 3–11.5 m/s. At touchdown, mid-stance, and take-off, athletes with BTTA had 0.01–0.05 lower Lratio at 3 m/s (p < 0.001) and 0.03–0.07 lower Lratio at 10 m/s (p < 0.001) in their ProsL compared to the BioL of NA athletes. During running, ProsL were consistently shorter than BioL. To achieve equivalent running leg lengths at touchdown and take-off, athletes with UTTA should set their running-specific prosthesis height so that their standing ProsL length is 2.8–4.5% longer than their BioL length, and athletes with BTTA should set their running-specific prosthesis height so that their standing ProsL lengths are at least 2.1–3.9% longer than their presumed BioL length. Setting ProsL length to match presumed biological dimensions during standing results in shorter legs during running.

A novel characterisation protocol of mechanical interactions between the ground and a tibial prosthesis for long jump

The mechanical study of Running Specific Prostheses (RSPs) is often limited to the blade. The setup developed and presented herein is a simple experiment, based on a mechanical testing machine and a camera, that assesses two indicators relevant to coaches and athletes in the field of athletics: secant stiffness and energy dissipation. The influence of four parameters on global prosthesis behaviour is evaluated: the load line offset, the prosthesis-ground angle, the sole type and the flooring type. The load line offset and the flooring type have little to no influence on their behaviour. The prosthesis-ground angle impacts the stiffness: an increase in the angle brings a significant decrease in stiffness, which strongly impacts the performance. The type of sole modifies the kinematics of the blade tip’s interaction with the ground. However, this effect is less likely to enhance the sports practice since athletics imposes the use of spikes. The camera images allow assessing the local behaviour of the sole, thus enabling to follow its strain through the compression process.

Sprinting performance of individuals with unilateral transfemoral amputation: compensation strategies for lower limb coordination.

Understanding the sprinting patterns of individuals with unilateral transfemoral amputation (uTFA) is important for designing improved running-specific prostheses and for prosthetic gait rehabilitation. Continuous relative phase (CRP) analysis acquires clues from movement kinematics and obtains insights into the sprinting coordination of individuals with uTFA. Seven individuals with uTFA sprinted on a 40 m runway. The spatio-temporal parameters, joint and segment angles of the lower limbs were obtained, and CRP analysis was performed on thigh-shank and shank-foot couplings. Subsequently, the asymmetry ratios of the parameters were calculated. Statistical analyses were performed between the lower limbs. Significant differences in the stance time, stance phase percentage, ankle joint angles and CRP of the shank-foot coupling (p < 0.05) were observed between the lower limbs. The primary contributor to these differences could be the structural differences between the lower limbs. Despite the presence of different coordination features in the stance and swing phases between the lower limbs, no significant difference in the coordination patterns of the thigh-shank coupling was observed. This may be a compensation strategy for achieving coordination patterns with improved symmetry between the lower limbs. The results of this study provide novel insights into the sprinting movement patterns of individuals with uTFA.

Spring-mass behavioural adaptations to acute changes in prosthetic blade stiffness during submaximal running in unilateral transtibial prosthesis users

BackgroundIndividuals with lower-limb amputation can use running specific prostheses (RSP) that store and then return elastic energy during stance. However, it is unclear whether varying the stiffness category of the same RSP affects spring-mass behaviour during self-selected, submaximal speed running in individuals with unilateral transtibial amputation. Research questionThe current study investigates how varying RSP stiffness affects limb stiffness, running performance, and associated joint kinetics in individuals with a unilateral transtibial amputation. MethodsKinematic and ground reaction force data were collected from eight males with unilateral transtibial amputation who ran at self-selected submaximal speeds along a 15 m runway in three RSP stiffness conditions; recommended habitual stiffness (HAB) and, following 10-minutes of familiarisation, stiffness categories above (+1) and below (-1) the HAB. Stance-phase centre of mass velocity, contact time, limb stiffness’ and joint/RSP work were computed for each limb across RSP stiffness conditions. ResultsWith increased RSP stiffness, prosthetic limb stiffness increased, whilst intact limb stiffness decreased slightly (p<0.03). Centre of mass forward velocity during stance-phase (p<0.02) and contact time (p<0.04) were higher in the intact limb and lower in the prosthetic limb but were unaffected by RSP stiffness. Intact limb hip joint positive work increased for both the +1 and -1 conditions but remained unchanged across conditions in the prosthetic limb (p<0.02). SignificanceIn response to changes in RSP stiffness, there were acute increased mechanical demands on the intact limb, reflecting a reliance on the intact limb during running. However, overall running speed was unaffected, suggesting participants acutely adapted to an RSP of a non-prescribed stiffness.

Running-specific prosthesis model, stiffness and height affect biomechanics and asymmetry of athletes with unilateral leg amputations across speeds.

Athletes with transtibial amputation (TTA) use running-specific prostheses (RSPs) to run. RSP configuration likely affects the biomechanics of such athletes across speeds. We determined how the use of three RSP models (Catapult, Sprinter and Xtend) with three stiffness categories (recommended, ±1), and three heights (recommended, ±2 cm) affected contact length (Lc), stance average vertical ground reaction force (Favg), step frequency (fstep) and asymmetry between legs for 10 athletes with unilateral TTA at 3–7 m s−1. The use of the Xtend versus Catapult RSP decreased Lc (p = 2.69 × 10−7) and Favg asymmetry (p = 0.032); the effect on Lc asymmetry diminished with faster speeds (p = 0.0020). The use of the Sprinter versus Catapult RSP decreased Favg asymmetry (p = 7.00 × 10−5); this effect was independent of speed (p = 0.90). The use of a stiffer RSP decreased Lc asymmetry (p ≤ 0.00033); this effect was independent of speed (p ≥ 0.071). The use of a shorter RSP decreased Lc (p = 5.86 × 10−6), Favg (p = 8.58 × 10−6) and fstep asymmetry (p = 0.0011); each effect was independent of speed (p ≥ 0.15). To minimize asymmetry, athletes with unilateral TTA should use an Xtend or Sprinter RSP with 2 cm shorter than recommended height and stiffness based on intended speed.

External Mechanical Work in Runners With Unilateral Transfemoral Amputation.

Carbon-fiber running-specific prostheses have enabled individuals with lower extremity amputation to run by providing a spring-like leg function in their affected limb. When individuals without amputation run at a constant speed on level ground, the net external mechanical work is zero at each step to maintain a symmetrical bouncing gait. Although the spring-like “bouncing step” using running-specific prostheses is considered a prerequisite for running, little is known about the underlying mechanisms for unilateral transfemoral amputees. The aim of this study was to investigate external mechanical work at different running speeds for unilateral transfemoral amputees wearing running-specific prostheses. Eight unilateral transfemoral amputees ran on a force-instrumented treadmill at a range of speeds (30, 40, 50, 60, 70, and 80% of the average speed of their 100-m personal records). We calculated the mechanical energy of the body center of mass (COM) by conducting a time-integration of the ground reaction forces in the sagittal plane. Then, the net external mechanical work was calculated as the difference between the mechanical energy at the initial and end of the stance phase. We found that the net external work in the affected limb tended to be greater than that in the unaffected limb across the six running speeds. Moreover, the net external work of the affected limb was found to be positive, while that of the unaffected limb was negative across the range of speeds. These results suggest that the COM of unilateral transfemoral amputees would be accelerated in the affected limb’s step and decelerated in the unaffected limb’s step at each bouncing step across different constant speeds. Therefore, unilateral transfemoral amputees with passive prostheses maintain their bouncing steps using a limb-specific strategy during running.

‘It’s more than just a running leg’: a qualitative study of running-specific prosthesis use by children and youth with lower limb absence

Purpose The purpose of this study was to investigate the use of running-specific prostheses (RSPs) by children with lower limb absence (LLA) along with the benefits and challenges of RSPs. Materials and methods In this descriptive qualitative study, eight children (ages 8–20 years) and their parents participated in semi-structured interviews. The interviews were audio-recorded and transcribed. Coded data were the foundation for central theme development. Results Three main themes were generated. “Run faster, jump higher, do more” (the benefits of RSP use), “Every leg serves its purpose” (comparing functionality between daily use prostheses and RSPs), and “A lot more to think about” (additional considerations with RSP use). Conclusions RSPs have a positive impact in promoting children’s engagement in sports and physical activities. While some children used their RSP primarily for running, others wore it for a broader range of physical activities. Issues with balance and discomfort caused by leg length discrepancies and/or ill-fitting sockets limited daily wear time. Limitations related to current RSP designs and clinical implementation should be addressed to optimize the functional potential of children with unilateral or bilateral LLA. Implications for rehabilitation Running-specific prostheses (RSPs) positively impacted children’s ability to participate in some sports with peers promoting their physical and social well-being. The main issues that children faced were discomfort, difficulty balancing, and inability to use RSPs for certain sports, while parents’ issues focused on supporting prosthesis use and transport, and adjustments of different prostheses to keep up with their child’s growth. Clinicians should be aware of the challenges of RSP use to best support children and their families. Designers should focus on addressing limitations with current RSPs to facilitate the diverse needs of pediatric users.

Metabolic Cost and Performance of Athletes With Lower Limb Amputation and Nonamputee Matched Controls During Running: A Systematic Review.

The elastic function of running-specific prostheses likely contributes to a lower metabolic cost of running. However, it remains unclear whether running-specific prostheses provide advantages concerning the metabolic cost of running in relationship with nonamputee runners. This study aimed to systematically review the scientific literature to examine the peak performance (peak oxygen consumption-VO2peak and peak speed) and the metabolic cost between paired amputees and nonamputees during running and between amputee runners with traditional prostheses and running-specific prostheses. A literature search on three databases (MEDLINE/PubMed, Scopus, and Web of Science) was conducted using the following key words: (amputation OR amputee) AND (run OR running OR runner) AND (prosthesis OR prosthetics), resulting in 2060 records and 4 studies within the inclusion criteria. A methodological quality assessment was carried out using a modified version of the Downs and Black checklist. VO2peak of the amputees athletes (54 ± 2 mL kg-1 min-1) is similar (mean difference = -0.80 mL kg-1 min-1, confidence interval = -4.63 to 3.03) to nonamputees athletes (55 ± 2 mL kg-1 min-1). The average metabolic cost of the paired amputee athletes (4.94 ± 1.19 J kg-1 m-1) also does not differ (mean difference = 0.73 J kg-1 m-1, confidence interval = -0.74 to 2.20) from nonamputee runners (4.21 ± 0.16 J kg-1 m-1). The research on running in amputee and nonamputee athletes is limited. The few existing studies have limited methodological quality. The metabolic cost data from amputee athletes running with running-specific prostheses are within the range of nonamputee data.

How Can Biomechanics Improve Physical Preparation and Performance in Paralympic Athletes? A Narrative Review.

Recent research in Paralympic biomechanics has offered opportunities for coaches, athletes, and sports practitioners to optimize training and performance, and recent systematic reviews have served to summarize the state of the evidence connecting biomechanics to Paralympic performance. This narrative review serves to provide a comprehensive and critical evaluation of the evidence related to biomechanics and Paralympic performance published since 2016. The main themes within this review focus on sport-specific body posture: the standing, sitting, and horizontal positions of current summer Paralympic sports. For standing sports, sprint and jump mechanics were assessed in athletes with cerebral palsy and in lower-limb amputee athletes using running-specific prostheses. Our findings suggest that running and jumping-specific prostheses should be ‘tuned’ to each athlete depending on specific event demands to optimize performance. Standing sports were also inclusive to athletes with visual impairments. Sitting sports comprise of athletes performing on a bike, in a wheelchair (WC), or in a boat. WC configuration is deemed an important consideration for injury prevention, mobility, and performance. Other sitting sports like hand-cycling, rowing, and canoeing/kayaking should focus on specific sitting positions (e.g., arm-crank position, grip, or seat configuration) and ways to reduce aero/hydrodynamic drag. Para-swimming practitioners should consider athlete-specific impairments, including asymmetrical anthropometrics, on the swim-start and free-swim velocities, with special considerations for drag factors. Taken together, we provide practitioners working in Paralympic sport with specific considerations on disability and event-specific training modalities and equipment configurations to optimize performance from a biomechanical perspective.

Asymmetry in Three-Dimensional Sprinting with and without Running-Specific Prostheses

As a whole, human sprinting seems to be a completely periodic and symmetrical motion. This view is changed when a person runs with a running-specific prosthesis after a unilateral amputation. The aim of our study is to investigate differences and similarities between unilateral below-knee amputee and non-amputee sprinters—especially with regard to whether asymmetry is a distracting factor for sprint performance. We established three-dimensional rigid multibody models of one unilateral transtibial amputee athlete and for reference purposes of three non-amputee athletes. They consist of 16 bodies (head, ipper, middle and lower trunk, upper and lower arms, hands, thighs, shanks and feet/running specific prosthesis) with 30 or 31 degrees of freedom (DOFs) for the amputee and the non-amputee athletes, respectively. Six DOFs are associated with the floating base, the remaining ones are rotational DOFs. The internal joints are equipped with torque actuators except for the prosthetic ankle joint. To model the spring-like properties of the prosthesis, the actuator is replaced by a linear spring-damper system. We consider a pair of steps which is modeled as a multiphase problem with each step consisting of a flight, touchdown and single-leg contact phase. Each phase is described by its own set of differential equations. By combining motion capture recordings with a least squares optimal control problem formulation including constraints, we reconstructed the dynamics of one sprinting trial for each athlete. The results show that even the non-amputee athletes showed less symmetrical sprinting than expected when examined on an individual level. Nevertheless, the asymmetry is much more pronounced in the amputee athlete. The amputee athlete applies larger torques in the arm and trunk joints to compensate the asymmetry and experiences a destabilizing influence of the trunk movement. Hence, the inter-limb asymmetry of the amputee has a significant effect on the control of the sprint movement and the maintenance of an upright body position.

Hip Joint Contact Loading and Muscle Forces During Running With a Transtibial Amputation.

People with unilateral transtibial amputations (TTA) have greater risks of bilateral hip osteoarthritis, related to asymmetric biomechanics compared to people without TTA. Running is beneficial for physical health and is gaining popularity. However, people with TTA may not have access to running-specific prostheses (RSPs), which are designed for running, and may instead run using their daily-use prosthesis (DUP). Differences in joint loading may result from prosthesis choice; thus, it is important to characterize changes in peak and impulsive hip joint contact loading during running. Six people with and without TTA ran at 3.5 m/s while ground reaction forces, kinematics, and electromyography were collected. People with TTA ran using their own RSP and DUP. Musculoskeletal models incorporating prosthesis type of each individual were used to quantify individual muscle forces and hip joint contact forces (HJCFs) during running. People using RSPs had smaller bilateral peak hip joint contact forces compared to when wearing DUPs during stance and swing, and a smaller impulse over the entire gait cycle. Greater amputated leg peak hip joint contact forces for people wearing DUPs compared to RSPs occurred with greater forces from the ipsilateral gluteus maximus during stance. People with TTA also had greater bilateral peak hip joint contact forces during swing compared to people without TTA, which occurred with greater peak gluteus medius forces. Running with more compliant RSPs may be beneficial for long-term joint health by reducing peak and impulsive hip loading compared to DUPs.

Anterior-posterior ground reaction forces across a range of running speeds in unilateral transfemoral amputees

ABSTRACT As a fundamental motor pattern, the ability to run at a range of constant speeds is a prerequisite for participating in competitive games and recreational sports. However, it remains unclear how unilateral transfemoral amputees modulate anterior and posterior ground reaction force impulses (GRFIs) in order to maintain constant running speeds. The purpose of this study was to investigate anterior and posterior GRFIs across a wide range of constant running speeds in unilateral transfemoral amputees wearing a running-specific prosthesis. Eleven runners with unilateral transfemoral amputation ran on an instrumented treadmill at 5 different speeds (30%, 40%, 50%, 60%, and 70% of the average velocity of their 100-m personal records). Anterior-posterior ground reaction forces (GRFs) were measured at 1000 Hz over 14 consecutive steps. Impulse, magnitude, and duration of anterior and posterior GRFs were compared between the affected and unaffected limbs at each speed. The net anterior-posterior GRFI, reflecting the changes in horizontal running velocity, was consistently positive (propulsion) in the affected limb and negative (braking) in the unaffected limb at all speeds. Regardless of running speed, unilateral transfemoral amputees maintain constant running speeds not over each step, but over 2 consecutive steps (i.e., one stride).

Development of Instrumented Running Prosthetic Feet for the Collection of Track Loads on Elite Athletes.

Knowledge of loads acting on running specific prostheses (RSP), and in particular on running prosthetic feet (RPF), is crucial for evaluating athletes’ technique, designing safe feet, and biomechanical modelling. The aim of this work was to develop a J-shaped and a C-shaped wearable instrumented running prosthetic foot (iRPF) starting from commercial RPF, suitable for load data collection on the track. The sensing elements are strain gauge bridges mounted on the foot in a configuration that allows decoupling loads parallel and normal to the socket-foot clamp during the stance phase. The system records data on lightweight athlete-worn loggers and transmits them via Wi-Fi to a base station for real-time monitoring. iRPF calibration procedure and static and dynamic validation of predicted ground-reaction forces against those measured by a force platform embedded in the track are reported. The potential application of this wearable system in estimating determinants of sprint performance is presented.