Vortex structure and fluid force changed by altering whole-body kinematic parameters during underwater undulatory swimming.

Swimmers generate vortices around their bodies during underwater undulatory swimming (UUS). Alteration of UUS movement would induce changes in vortex structure and fluid force. This study investigated whether a skilled swimmer's movement generated an effective vortex and fluid force for increasing the UUS velocity.

Measurements of tendon length changes during stretch-shortening cycles in rat soleus.

The muscle force attained during concentric contractions is augmented by a preceding eccentric contraction (the stretch-shortening cycle (SSC) effect). At present, tendon elongation is considered the primary mechanism. However, we recently found that the magnitude of the SSC effect was not different, even after removing the Achilles tendon.

The Large and Strong Vortex Around the Trunk and Behind the Swimmer is Associated with Great Performance in Underwater Undulatory Swimming.

Swimmers can produce horizontal body velocity by generating and shedding vortices around their body during underwater undulatory swimming (UUS). It has been hypothesized that the horizontal shedding velocity, area and circulation of the vortex around the swimmer's body are associated with UUS performance. The purpose of this study was to investigate whether the shedding velocity, area and circulation of vortices around swimmers' bodies are correlated with the horizontal body velocity during UUS.

Biomechanical determinants of top running speeds in para-athletes with unilateral transfemoral amputation.

Background: An increased understanding of biomechanical determinants that influence the sprint performance of para-athletes with a unilateral transfemoral amputation will provide us with a basis for better evaluating athletes' sprint performance and would be expected to aid in the development of more effective training methods and running-specific prosthesis selection guidelines.

Objectives: The aim of this study was to investigate the relative contributions of mechanical determinants to the top running speeds of para-athletes with unilateral transfemoral amputation wearing a running-specific prosthesis.

Study Design: Observational study within the subject.

Competitive-Level Differences in Trunk and Foot Kinematics of Underwater Undulatory Swimming.

The foot and trunk kinematics could be associated with horizontal velocity during underwater undulatory swimming (UUS). This study aimed to compare the foot and trunk kinematic parameters during UUS between faster and slower swimmers. The three-dimensional coordinates of the markers were collected during 15 m UUS for 13 swimmers.

Unilateral above-knee amputees achieve symmetric mediolateral ground reaction impulse in walking using an asymmetric gait strategy.

The ability to sustain steady straight-ahead walking is one goal of gait rehabilitation for individuals with unilateral above-knee (UAK) amputation. Despite the morphological and musculoskeletal asymmetry resulting from unilateral limb loss, the mediolateral ground-reaction-impulse (GRI) should be counterbalanced between the affected and unaffected limbs during straight-ahead walking. Therefore, we investigated the strategies of mediolateral ground-reaction-force (GRF) generation adopted by UAK prosthesis users walking along a straight path.

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

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.

Walking characteristics of runners with a transfemoral or knee-disarticulation prosthesis.

Background: Running with prostheses has become a common activity for amputees participating in sports and recreation. However, very few studies have characterized the kinematic and kinetic parameters of walking in individuals with amputation who are runners. Thus, this study attempts to elucidate the kinematics and kinetics of walking in runners with a unilateral transfemoral amputation or knee-disarticulation.

Loading rates in unilateral transfemoral amputees with running-specific prostheses across a range of speeds.

Background: Understanding the potential risks of running-related injuries in unilateral transfemoral amputees contributes to the development and implementation of the injury prevention programme in running gait rehabilitation. We investigated the vertical ground reaction force loading in unilateral transfemoral amputees who used running-specific prostheses across a range of running speeds.

Methods: Ten unilateral transfemoral amputees and ten non-amputees performed running trials on an instrumented treadmill at the incremental speeds of 30, 40, 50, and 60% of their maximum acquired speeds.

Effect of step frequency on leg stiffness during running in unilateral transfemoral amputees.

Spring-like leg behavior is a general feature of mammalian bouncing gaits, such as running and hopping. Although increases in step frequency at a given running speed are known to increase the stiffness of the leg spring (k) in non-amputees, little is known about stiffness regulation in unilateral transfemoral amputees. In this study, we investigated stiffness regulation at different step frequencies at a given running speed in unilateral transfemoral amputees.

Factors associated with a risk of prosthetic knee buckling during walking in unilateral transfemoral amputees.

Background: Walking and mobility are essential for a satisfactory quality of life. However, individuals with transfemoral amputations have difficulties in preventing falls due to prosthetic knee buckling, defined as the sudden loss of postural support during weight-bearing activities. The risk of prosthetic knee buckling can be evaluated by determining the prosthetic knee angular impulse (PKAI) during the early stance phase.

A Limb-specific Strategy across a Range of Running Speeds in Transfemoral Amputees.

Purpose: This study investigated the vertical ground reaction force (vGRF) variables and spatiotemporal parameters related to running speed across a range of speeds in sprinters with unilateral transfemoral amputation who used running-specific prostheses (RSPs).

Methods: Ten sprinters with unilateral transfemoral amputation ran on an instrumented treadmill at incremental speeds of 30%, 40%, 50%, 60%, and 70% of the average speed of their 100-m personal best (100%) while using their RSPs. The vGRF data were collected at 1000 Hz during each trial.

Vertical stiffness during one-legged hopping with and without using a running-specific prosthesis.

Although athletes with unilateral below-the-knee amputations (BKAs) generally use their affected leg, including their prosthesis, as their take-off leg for the long jump, little is known about the spring-like leg behavior and stiffness regulation of the affected leg. The purpose of this study was to investigate vertical stiffness during one-legged hopping in an elite-level long jump athlete with a unilateral BKA. We used the spring-mass model to calculate vertical stiffness, which equals the ratio of maximum vertical ground reaction force to maximum center of mass displacement, while the athlete with a BKA hopped on one leg at a range of frequencies.

Joint moments during sprinting in unilateral transfemoral amputees wearing running-specific prostheses.

Knowledge of joint moments will provide greater insight into the manner in which lower-extremity amputees wearing running-specific prostheses regain running capacity and compensate for replacement of an active leg with a passive prosthetic implement. Thus, the purpose of this study was to investigate three-dimensional joint moments during sprinting for unilateral transfemoral amputees wearing running-specific prostheses. Ten sprinters with unilateral transfemoral amputation performed maximal sprinting at the 22 m mark while wearing running-specific prostheses.

Leg stiffness in unilateral transfemoral amputees across a range of running speeds.

Carbon fiber running-specific prostheses have allowed lower extremity amputees to participate in running activity by providing spring-like properties in their affected limb. It has been established that as running speed increases, stiffness of the leg spring (leg stiffness; k) remains constant in non-amputees. Although a better understanding of k regulation may be helpful for the development of spring-based prostheses, little is known about stiffness regulation in unilateral transfemoral amputees.

Inter-Individual Variability in The Joint Negative Work During Running.

The inter-individual variability of running technique is an important factor affecting the negative work of lower extremity joints that leads to muscle damage. Our study examines the relationships between the negative work of the lower extremity joints and the associated mechanical parameters that account for inter-individual variability in the negative work. Twenty-four young male adults were asked to run on a runway at a speed of 3.

Between-limb differences in running technique induces asymmetric negative joint work during running.

Negative work, which is mainly generated by eccentric muscle contraction, has an important influence on the associated muscle damage. Generally, mechanical parameters are determined for one side of a lower extremity on the assumption of negligible between-limb differences. However, between-limb differences in the negative work of lower extremity joints during running remain unclear.

Spatiotemporal parameters in sprinters with unilateral and bilateral transfemoral amputations and functional impairments.

Purpose: Although sprinters with unilateral (UTF) and bilateral transfemoral (BTF) amputations and functional impairments (FIs) without amputation were allocated into different classifications because of the recent revision of the International Paralympic Committee Athletics Rules and Regulations, it is unclear whether running mechanics differ among the three groups. The aim of this study was to investigate the differences in the spatiotemporal parameters of the three groups during 100-m sprint in official competitions.

Methods: Using publicly available Internet broadcasts, we analyzed 11 elite-level sprinters with UTF amputation, 4 sprinters with BTF amputation, and 5 sprinters with FI without amputation.

Individual Step Characteristics During Sprinting in Unilateral Transtibial Amputees.

To understand the step characteristics during sprinting in lower-extremity amputees using running-specific prosthesis, each athlete should be investigated individually. Theoretically, sprint performance in a 100-m sprint is determined by both step frequency and step length. The aim of the present study was to investigate how step frequency and step length correlate with sprinting performance in elite unilateral transtibial amputees.

Differences in spatiotemporal parameters during 200-m sprint between bilateral and unilateral transfemoral amputees.

Background And Aim:: Although Paralympic T42 class Men's 200 m sprints are currently competed by athletes with bilateral and unilateral transfemoral amputations, there may be performance differences between the groups. This study aimed to compare the spatiotemporal parameters of a 200-m sprint between bilateral and unilateral transfemoral amputees wearing running-specific prostheses.

Technique:: We analyzed 29 races (nine sprinters) with bilateral or unilateral transfemoral amputations from publicly available Internet broadcasts.

Modeling and analysis of individual with lower extremity amputation locomotion using prosthetic feet and running-specific prostheses.

Prostheses have enabled individuals with lower extremity amputation (ILEAs) to accomplish many daily activities. Prosthetic feet allow ILEA to locomote and improves their quality of life. Carbon-fiber running-specific prostheses (RSPs) with energy storing capabilities support ILEAs to perform sprinting by partly providing spring-like properties in their amputated legs.

Training Shoes do not Decrease the Negative Work of the Lower Extremity Joints.

Different types of running shoes may have different influence on the negative work of each lower extremity joint. Clarifying this influence can reduce the potential risk of muscle injury. The present study examined the difference in the negative work and associated kinetic and kinematic parameters of the lower extremity joints between training shoes and racing flats during the contact phase of running.

Ground Reaction Forces During Sprinting in Unilateral Transfemoral Amputees.

Understanding the characteristics of ground reaction forces (GRFs) on both limbs during sprinting in unilateral amputees wearing running-specific prostheses would provide important information that could be utilized in the evaluation of athletic performance and development of training methods in this population. The purpose of this study was to compare GRFs between intact and prosthetic limbs during sprinting in unilateral transfemoral amputees wearing running-specific prostheses. Nine sprinters with unilateral transfemoral amputation wearing the same type of prosthesis performed maximal sprinting on a 40-m runway.

Leg stiffness during sprinting in transfemoral amputees with running-specific prosthesis.

Carbon fiber running-specific prostheses are designed to reproduce the spring-like stepping behavior of individuals similar to springs loaded by the entire body mass (i.e. spring-mass model).