Stride Frequency Research Articles

The human lower leg muscle pump functions as a flow diverter pump, maintaining low ambulatory venous pressures during locomotion

ObjectiveAmbulatory venous pressure (AVP) is the drop of pressure observed in the superficial veins of the lower leg during movement. This phenomenon has been linked to the function of the calf muscle pump (CMP) and the competence of venous valves. Nevertheless, the concept of the CMP function remains controversial. This study aimed to elucidate the association between lower leg muscles activity, changes in pressure in distinct venous segments, and lower extremity arterial blood supply in healthy subjects during various types and intensities of exercise. MethodsTwelve legs of nine healthy volunteers were enrolled in the study. Continuous pressure (intramuscular vein [IV] and three great saphenous vein [GSV] points) and surface electromyography data (gastrocnemius and anterior tibial [ATM] muscles) were recorded during treadmill walking, running, and plantar flexion exercises. The pressure gradient (ΔP, mmHg) between adjacent points of measurement was calculated. Minute unit power of muscle pump ejection and suction (NE, and NS, MPa/min) were calculated and compared with the arterial blood supply of the lower extremity (LBF, L/min). ResultsΔP demonstrated a consistent pattern of changes during walking and running. In GSV, the ΔP was observed to be directed from the thigh to the mid-calf (retrogradely) and from the ankle to the mid-calf (anterogradely) throughout the entire stride cycle. However, its value decreased with increasing stride cycle frequency. The dynamics of ΔP between the IV and GSV were as follows: It was directed from the IV to GSV during gastrocnemius contraction and was reversed during anterior tibial muscle contraction and gastrocnemius relaxation (swing phase). LBF, NE, and NS demonstrated similar exponential growth with increasing stride frequency during walking and running. ConclusionsDuring natural locomotion, the muscle pump acts as a flow diverter pump, redirecting the flow of blood from the superficial veins to the intramuscular veins via the perforating veins. During ambulation, the pressure in the superficial venous network depends upon the capacity of the muscle pump to provide output that matches the changes in arterial blood flow.

Early gait analysis after total knee arthroplasty based on artificial intelligence dynamic image recognition

To explore early postoperative gait characteristics and clinical outcomes after total knee arthroplasty (TKA). From February 2023 to July 2023, 26 patients with unilateral knee osteoarthritis (KOA) were treated with TKA, including 4 males and 22 females, aged from 57 to 85 years old with an average of (67.58±6.49) years old;body mass index (BMI) ranged from 18.83 to 38.28 kg·m-2 with an average of (26.43±4.15) kg·m-2;14 patients on the left side, 12 patients on the right side;according to Kellgren-Lawrence(K-L) classification, 6 patients with grade Ⅲ and 20 patients with grade IV;the courses of disease ranged from 1 to 14 years with an average of (5.54±3.29) years. Images and videos of standing up and walking, walking side shot, squatting and supine kneeling were taken with smart phones before operation and 6 weeks after operation. The human posture estimation framework OpenPose were used to analyze stride frequency, step length, step length, step speed, active knee knee bending angle, stride length, double support phase time, as well as maximum hip flexion angle and maximum knee bending angle on squatting position. Western Ontario and McMaster Universities (WOMAC) arthritis index and Knee Society Score (KSS) were used to evaluate clinical efficacy of knee joint. All patients were followed up for 5 to 7 weeks with an average of (6.00±0.57) weeks. The total score of WOMAC decreased from (64.85±11.54) before operation to (45.81±7.91) at 6 weeks after operation (P<0.001). The total KSS was increased from (101.19±9.58) before operation to (125.50±10.32) at 6 weeks after operation (P<0.001). The gait speed, stride frequency and stride length of the affected side before operation were (0.32±0.10) m·s-1, (96.35±24.18) steps·min-1, (0.72±0.14) m, respectively;and increased to (0.48±0.11) m·s-1, (104.20±22.53) steps·min-1, (0.79±0.10) m at 6 weeks after operation (P<0.05). The lower limb support time and active knee bending angle decreased from (0.31±0.38) s and (125.21±11.64) ° before operation to (0.11±0.04) s and (120.01±13.35) ° at 6 weeks after operation (P<0.05). Eleven patients could able to complete squat before operation, 13 patients could able to complete at 6 weeks after operation, and 9 patients could able to complete both before operation and 6 weeks after operation. In 9 patients, the maximum bending angle of crouching position was increased from 76.29° to 124.11° before operation to 91.35° to 134.12° at 6 weeks after operation, and the maximum bending angle of hip was increased from 103.70° to 147.25° before operation to 118.61° to 149.48° at 6 weeks after operation. Gait analysis technology based on artificial intelligence image recognition is a safe and effective method to quantitatively identify the changes of patients' gait. Knee pain of KOA was relieved and the function was improved, the supporting ability of the affected limb was improved after TKA, and the patient's stride frequency, stride length and stride speed were improved, and the overall movement rhythm of both lower limbs are more coordinated.

Interlimb coordination is not strictly controlled during walking

In human walking, the left and right legs move alternately, half a stride out of phase with each other. Although various parameters, such as stride frequency and length, vary with walking speed, the antiphase relationship remains unchanged. In contrast, during walking in left-right asymmetric situations, the relative phase shifts from the antiphase condition to compensate for the asymmetry. Interlimb coordination is important for adaptive walking and we expect that interlimb coordination is strictly controlled during walking. However, the control mechanism remains unclear. In the present study, we derived a quantity that models the control of interlimb coordination during walking using two coupled oscillators based on the phase reduction theory and Bayesian inference method. The results were not what we expected. Specifically, we found that the relative phase is not actively controlled until the deviation from the antiphase condition exceeds a certain threshold. In other words, the control of interlimb coordination has a dead zone like that in the case of the steering wheel of an automobile. It is conjectured that such forgoing of control enhances energy efficiency and maneuverability. Our discovery of the dead zone in the control of interlimb coordination provides useful insight for understanding gait control in humans.

Kinematical Effects of a Mandibular Advancement Occlusal Splint on Running until Exhaustion at Severe Intensity.

The effects of occlusal splints on sport performance have already been studied, although their biomechanical impacts are often overlooked. We investigated the kinematical changes during running until exhaustion at severe intensity while wearing a mandibular advancement occlusal splint. Twelve trained runners completed (i) an incremental protocol on a track to determine their velocity corresponding to maximal oxygen uptake and (ii) two trials of square wave transition exercises at their velocity corresponding to maximal oxygen until exhaustion, wearing two occlusal splints (without and with mandibular advancement). Running kinematics were compared within laps performed during the square wave transition exercises and between splint conditions. The mandibular advancement occlusal splint increased the running distance covered (~1663 ± 402 vs. 1540 ± 397 m, p = 0.03), along with a noticeable lap effect in decreasing stride frequency (p = 0.04) and increasing stride length (p = 0.03) and duty factor (p < 0.001). No spatiotemporal differences were observed between splints, except for improved balance foot contact times in the mandibular advancement condition. An increased knee flexion angle at initial contact (p = 0.017) was noted along laps in the non-advancement condition, despite the fact that no differences between splints were found. Running patterns mainly shifted within laps rather than between conditions, indicating that a mandibular advancement occlusal splint had a trivial kinematical effect.

Comparative kinematic analysis of high-speed treadmill vs. overground sprinting across athletic levels and sex.

This investigation aimed to dissect the kinematic differences in sprinting between high-speed treadmill and overground conditions, examining how these variations are influenced by the athlete's training status and biological sex. A total of 40 participants, 20 NCAA Division 1 sprinters and 20 recreational runners, performed a series of maximal sprints on a high-speed treadmill and on a standardized competition overground track. Sprinting kinematic variables such as stride length, stride frequency, contact time, and flight time were collected via photoelectric sensors. Maximal sprinting kinematics were analyzed by linear mixed-effects models, considering the impacts of sprinting environment (treadmill vs. overground), training level, and sex, with leg length as fixed factors and individual athletes as random effects. Statistical significance was set at a significance level of 0.05. The statistical analysis revealed that high-speed treadmill sprinting significantly affects all measured kinematic variables, leading to increased stride frequency and contact time. Elite sprinters demonstrated enhanced kinematic efficiency over recreational runners, characterized by increased stride length and frequency and reduced contact time. Sex-based kinematic distinctions also emerged, with male athletes exhibiting superior stride length and frequency compared to female athletes. Leg length significantly influenced stride frequency, and an interaction effect was observed for flight time between sprint type and athletic group. These findings elucidate the distinct biomechanical profiles across sprinting modalities and athlete demographics, emphasizing the need for sprint training customization. This study's insights offer a valuable reference for coaches and athletes to refine training and performance assessment in varied sprinting environments.

Correlation between kinematic parameters, ataxia and ground-to-lip distance in detomidine sedated horses.

An accurate evaluation of the degree of sedation is mandatory to adjust the dosage of sedative drugs. To determine the correlation between head height above the ground and ataxia degree in horses sedated with detomidine and the correlation existing between accelerometric variables and both parameters. Retrospective study. Twelve horses were given 0.01 mg/kg of detomidine hydrochloride iv. Measured accelerometric parameters, with one accelerometer positioned between both sacral tuberosities, included speed, stride frequency and length, regularity, dorsoventral, longitudinal, mediolateral and total accelerometric activities, relative force index and dorsoventral, longitudinal and mediolateral parts of the accelerometric activities. Head height above the ground (cm) and subjective ataxia degree were also measured. Baseline values (-15 min) and values measured 5 and 15 min after the injection and then every 15 min for a period of 2 h were obtained. There was a negative and strong correlation between head height above the ground and ataxia degree (Pearson r = -0.78, p < 0.001), particularly during the first 45 min. A significant correlation was found between head height above the ground and almost all accelerometric parameters. This correlation was very strong with stride frequency, regularity and dorsoventral and total accelerometric activities in both cases, but for ataxia, also with total accelerometric activity. Experimental conditions may not represent real clinical situations. Stride frequency and regularity are the most reliable parameters to determine degree of sedation and are related to the sedation produced. Ataxia should not be considered a separate property of sedation and does not need to be assessed separately to the depth of sedation.

Effect of Intermittent Theta Burst Stimulation Dual-Target Stimulation on Lower Limb Function in Patients with Incomplete Spinal Cord Injury: A Randomized, Single-Blind, Sham-Controlled Study

To explore the influence of intermittent theta burst stimulation (iTBS) dual-target stimulation on lower limb function in patients with incomplete spinal cord injury (iSCI). A randomized, single -blind, sham-controlled trial was used in this study. Thirty iSCI patients with lower limb dysfunction meeting the inclusion criteria were randomly divided into a sham group and an iTBS group, with 15 cases in each group. The iTBS group received conventional rehabilitation therapy combined with iTBS dual-target stimulation on the central cerebral sulcus and the nerve root of the spinal cord injury segment. The sham group was treated with conventional rehabilitation therapy combined with iTBS dual-target sham stimulation therapy. Comprehensive functional assessment was performed on all patients before treatment, on the day 3 and day 21 of treatment. The main evaluation indicators were as follows: amplitude and latency of motor-evoked potential (MEP) in the anterior tibial muscles of both lower limbs, latency of sensory-evoked potential (SEP) of both lower limbs, knee flexor strength and knee extensor strength, lower extremity motor score (LEMS), lower extremity sensory score, spinal cord independence measure (SCIM) score, and gait parameters (stride speed, stride frequency, stride length, and ground reaction force). On day 21 of treatment, in the iTBS group, the MEP amplitude of the anterior tibial muscles increased, the latency of MEP shortened, knee flexor strength and knee extensor strength increased, and the LEMS and SCIM score of both lower limbs increased. In addition, there were statistically significant differences in the muscle strength of the knee flexion muscle, knee extensor muscle, MEP amplitude, LEMS, and SCIM between the 2 groups (P < 0.05). Among the 10 patients who could walk with an assisted walker, the step length and step frequency of the iTBS group were increased compared with the sham group after treatment (P < 0.01), and the ground reaction force was increased (P < 0.05). There was no significant difference in the lower extremity sensory score of the lower limbs between the 2 groups (P>0.05). ITBS dual-target stimulation can significantly improve the motor function of both lower limbs in patients with iSCI but does not significantly improve the sensory function of both lower limbs. Therefore, this treatment mode may participate in the reconstruction and repair of some nerve circuits in patients with iSCI. In addition, iTBS dual-target stimulation can improve the ability of iSCI patients to perform daily living.

The efficacy of 3D gait analysis to evaluate surgical (and rehabilitation) outcome after degenerative lumbar surgery

BackgroundLumbar degenerative conditions are a major cause of back pain and disability in individuals aged 45 and above. Gait analysis utilizes sensor technology to collect movement data, aiding in the evaluation of various gait aspects like spatiotemporal parameters, joint angles, neuromuscular activity, and joint forces. It is widely used in conditions such as cerebral palsy and knee osteoarthritis. This research aims to assess the effectiveness of 3D gait analysis in evaluating surgical outcomes and postoperative rehabilitation for lumbar degenerative disorders.MethodsA prospective self-controlled before-after study (n = 85) carried out at our Hospital (Sep 2018 - Dec 2021) utilized a 3D motion analysis system to analyze gait in patients with lumbar degenerative diseases. The study focused on the multifidus muscle, a crucial spinal muscle, during a minimally invasive lumbar interbody fusion surgery conducted by Shandong Weigao Pharmaceutical Co., Ltd. Pre- and postoperative assessments included time-distance parameters (gait speed, stride frequency, stride length, stance phase), hip flexion angle, and stride angle. Changes in 3D gait parameters post-surgery and during rehabilitation were examined. Pearson correlation coefficient was employed to assess relationships with the visual analog pain scale (VAS), Oswestry Disability Index (ODI), and Japanese Orthopedic Association (JOA) scores. Patient sagittal alignment was evaluated using “Surgimap” software from two types of lateral radiographs to obtain parameters like pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), intervertebral space height (DH), posterior height of the intervertebral space (PDH) at the operative segment, and anterior height of the intervertebral space (ADH).ResultsBy the 6th week post-operation, significant improvements were observed in the VAS score, JOA score, and ODI score of the patients compared to preoperative values (P < 0.05), along with notable enhancements in 3D gait quantification parameters (P < 0.05). Pearson correlation analysis revealed a significant positive correlation between improvements in 3D gait quantification parameters and VAS score, JOA score, and ODI value (all P < 0.001).Conclusion3D gait analysis is a valuable tool for evaluating the efficacy of surgery and rehabilitation training in patients.

Consistency of sex-based differences between treadmill and overground running using an inertial measurement unit (IMU)

Differences in running gait between treadmill and overground running has been subject of study, while consistency of group differences between running surfaces has not been previously analysed. This study examined both the differences between running surfaces and the consistency of sex-based differences between surfaces in some spatiotemporal and kinematic variables measured by an inertial measurement unit fastened over the lumbar spine. Thirty-two (sixteen females) endurance runners firstly performed overground and then treadmill (1 % inclination) runs at speeds between 9–21 km∙h−1. Males showed lower flight time (FT) [moderate effect size (ES)] during treadmill running compared to overground, while females showed greater stride frequency (SF) (moderate ES), lower stride length (SL) (moderate ES), FT (moderate ES), and vertical (VT) trunk displacement (moderate ES), as well as greater medio-lateral (ML) trunk displacement (moderate ES). No differences in CT between surfaces were found (trivial to small). Furthermore, all the sex-differences were consistent between treadmill and overground running: Males showed lower SF (large and moderate ES, respectively), greater SL (large and moderate ES) and CT (moderate and large ES), lower FT (large ES), greater VT displacement (moderate to large ES), and lower ML displacement (moderate ES) than females. These results may be of interest to carefully transfer the running gait analyses between surfaces depending on sex.

Effects of Cognitive-Motor and Motor-Motor Dual Tasks on Gait Performance in Older Adults with Sarcopenia.

With the advent of global aging, the health of the older population has become a critical public health challenge. The purpose of this study was to investigate the effect of dual-tasking on gait performance in patients with sarcopenia. Thirty participants with sarcopenia (age: 70.73 ± 4.12 yr, MMSE score: 26.90 ± 3.00), including 14 males and 16 females, were selected according to the diagnostic criteria of the Asian Working Group on Sarcopenia. All participants were instructed to perform the gait test in three modes: single task (ST), cognitive-motor dual task (CMDT), and motor-motor dual task (MMDT). Statistical analyses were performed using one-way ANOVA to evaluate the effects of different task types on gait parameters of the participants. (1) Compared with ST walking, gait frequency, step length, and step speed decreased, and the gait cycle and double-support phase increased in patients with sarcopenia during dual-task walking (p < 0.05); (2) Compared with ST walking, gait variability indices such as stride frequency, stride length, and support period significantly increased in patients with sarcopenia during dual-task walking (p < 0.05). The increased difficulty in postural control caused by dual-task interference may reduce the safety of motor strategies in patients with sarcopenia and increase the risk of falls. Future studies should focus on the effects of exercise interventions on multitasking patterns in people with sarcopenia to promote balance function in these populations.

The application of a single session of capacitive resistive electric transfer 24 h before exercise modifies the accelerometric pattern in standardbred racing trotters

BackgroundIt has been reported that capacitive resistive electric transfer (CRET) increases blood circulation, hemoglobin oxygenation and temperature in muscles. The attributed benefits of these changes have been linked to improved athletic performance, enhanced muscle flexibility and fastening recovery from exercise-induced fatigue. For all of this, the present research aims to investigate whether the application of CRET 24 h before exercise affects the accelerometric pattern in horses during exercise. Six sound Standardbred trotters were subjected to a CRET session of 40 min of duration, applied on both sides of the neck, back and croup, 24 h before a training session. Training sessions consisted of a warming-up (WU) for 6400 m and a training bout (TB) at their maximal training speed for 1600 m. The same protocol was followed for the device off (sham protocol), also applied 24 h before the training session. CRET and sham experiments were separated by one week, the order of application of both was randomly defined for each individual and drivers were blinded for the duration of the experiment. During the training sessions, horses wore an accelerometer fixed at the sternal level. Speed, stride frequency (SF), length (SL), regularity and symmetry and accelerometric activities were measured during WU and TB.ResultsCRET increased speed, mediolateral and total accelerometric activities during WU and speed, SL, dorsoventral, longitudinal and total accelerometric activities during TB, but stride regularity and symmetry decreased.ConclusionThe application of CRET 24 h before exercise increased speed and accelerometric activities, results that highlight the need to evaluate the interaction between CRET and training in order to develop new methods to limit fatigue. However, the decrease in stride regularity and symmetry after CRET application could be negative effects, which could be attributed to the increased speed.

Stem cell exosome-loaded Gelfoam improves locomotor dysfunction and neuropathic pain in a rat model of spinal cord injury.

Spinal cord injury (SCI) is a debilitating illness in humans that causes permanent loss of movement or sensation. To treat SCI, exosomes, with their unique benefits, can circumvent limitations through direct stem cell transplantation. Therefore, we utilized Gelfoam encapsulated with exosomes derived from human umbilical cord mesenchymal stem cells (HucMSC-EX) in a rat SCI model. SCI model was established through hemisection surgery in T9 spinal cord of female Sprague-Dawley rats. Exosome-loaded Gelfoam was implanted into the lesion site. An in vivo uptake assay using labeled exosomes was conducted on day 3 post-implantation. Locomotor functions and gait analyses were assessed using Basso-Beattie-Bresnahan (BBB) locomotor rating scale and DigiGait Imaging System from weeks 1 to 8. Nociceptive responses were evaluated through von Frey filament and noxious radiant heat tests. The therapeutic effects and potential mechanisms were analyzed using Western blotting and immunofluorescence staining at week 8 post-SCI. For the in vivo exosome uptake assay, we observed the uptake of labeled exosomes by NeuN+, Iba1+, GFAP+, and OLIG2+ cells around the injured area. Exosome treatment consistently increased the BBB score from 1 to 8 weeks compared with the Gelfoam-saline and SCI control groups. Additionally, exosome treatment significantly improved gait abnormalities including right-to-left hind paw contact area ratio, stance/stride, stride length, stride frequency, and swing duration, validating motor function recovery. Immunostaining and Western blotting revealed high expression of NF200, MBP, GAP43, synaptophysin, and PSD95 in exosome treatment group, indicating the promotion of nerve regeneration, remyelination, and synapse formation. Interestingly, exosome treatment reduced SCI-induced upregulation of GFAP and CSPG. Furthermore, levels of Bax, p75NTR, Iba1, and iNOS were reduced around the injured area, suggesting anti-inflammatory and anti-apoptotic effects. Moreover, exosome treatment alleviated SCI-induced pain behaviors and reduced pain-associated proteins (BDNF, TRPV1, and Cav3.2). Exosomal miRNA analysis revealed several promising therapeutic miRNAs. The cell culture study also confirmed the neurotrophic effect of HucMSCs-EX. Implantation of HucMSCs-EX-encapsulated Gelfoam improves SCI-induced motor dysfunction and neuropathic pain, possibly through its capabilities in nerve regeneration, remyelination, anti-inflammation, and anti-apoptosis. Overall, exosomes could serve as a promising therapeutic alternative for SCI treatment.

Pharmacological inhibition of STING reduces neuroinflammation-mediated damage post-traumatic brain injury.

Traumatic brain injury (TBI) remains a major public health concern worldwide with unmet effective treatment. Stimulator of interferon genes (STING) and its downstream type-I interferon (IFN) signalling are now appreciated to be involved in TBI pathogenesis. Compelling evidence have shown that STING and type-I IFNs are key in mediating the detrimental neuroinflammatory response after TBI. Therefore, pharmacological inhibition of STING presents a viable therapeutic opportunity in combating the detrimental neuroinflammatory response after TBI. This study investigated the neuroprotective effects of the small-molecule STING inhibitor n-(4-iodophenyl)-5-nitrofuran-2-carboxamide (C-176) in the controlled cortical impact mouse model of TBI in 10- to 12-week-old male mice. Thirty minutes post-controlled cortical impact surgery, a single 750-nmol dose of C-176 or saline (vehicle) was administered intravenously. Analysis was conducted 2h and 24 h post-TBI. Mice administered C-176 had significantly smaller cortical lesion area when compared to vehicle-treated mice 24 h post-TBI. Quantitative temporal gait analysis conducted using DigiGait™ showed C-176 administration attenuated TBI-induced impairments in gait symmetry, stride frequency and forelimb stance width. C-176-treated mice displayed a significant reduction in striatal gene expression of pro-inflammatory cytokines Tnf-α, Il-1β and Cxcl10 compared to their vehicle-treated counterparts 2h post-TBI. This study demonstrates the neuroprotective activity of C-176 in ameliorating acute neuroinflammation and preventing white matter neurodegeneration post-TBI. This study highlights the therapeutic potential of small-molecule inhibitors targeting STING for the treatment of trauma-induced inflammation and neuroprotective potential.

Dynamic Response Study of Space Large-Span Structure under Stochastic Crowd-Loading Excitation

With the development of civil engineering, lightweight and high-strength materials, as well as large-span, low-frequency structural systems, are increasingly used. However, its self-oscillation frequency is often close to the stride frequency of pedestrians, which is easily affected by human activities. To study the effect of human activities on the dynamic response of structures, it is crucial to choose an appropriate anthropogenic load model. Considering the inter-subject and intra-subject variability of pedestrian walking parameters and induced forces in a crowd, we introduce the interaction rules between pedestrians based on the floor field cellular automata (FFCA). A stochastic crowd-loading model coupling walking parameters, induced forces between pedestrians, and induced forces between pedestrians and structures is proposed for simulating crowd-walking loads. The feasibility of the model is verified by comparing the measured response of a space large-span structure with the predicted response of the proposed stochastic crowd-loading model. The comfort level of the structure under different crowd densities was also evaluated based on the model. It was found that both random combinations of walking parameters and dynamic behaviors of pedestrians can cause significant differences in the structural response. Therefore, the crowd-loading model should consider the influence of pedestrian behavioral factors on the structural response.

The work to swing limbs in humans versus chimpanzees and its relation to the metabolic cost of walking

Compared to their closest ape relatives, humans walk bipedally with lower metabolic cost (C) and less mechanical work to move their body center of mass (external mechanical work, WEXT). However, differences in WEXT are not large enough to explain the observed lower C: humans may also do less work to move limbs relative to their body center of mass (internal kinetic mechanical work, WINT,k). From published data, we estimated differences in WINT,k, total mechanical work (WTOT), and efficiency between humans and chimpanzees walking bipedally. Estimated WINT,k is ~ 60% lower in humans due to changes in limb mass distribution, lower stride frequency and duty factor. When summing WINT,k to WEXT, between-species differences in efficiency are smaller than those in C; variations in WTOT correlate with between-species, but not within-species, differences in C. These results partially support the hypothesis that the low cost of human walking is due to the concerted low WINT,k and WEXT.

Differences in behaviour, facial expressions and locomotion between positive anticipation and frustration in horses

Animal welfare is a result of accumulated negative and positive emotions. Therefore, it is important to limit the former and promote the latter. Doing so requires a precise identification of these emotions. The aim of this study was to characterize the behaviours, facial expressions and locomotor parameters of 21 horses in two conditions with opposite valence, presumed to induce positive anticipation and frustration. In the positive anticipation situation, the horse was led to a bucket of food, knowing that they would be allowed to eat it. In the frustration situation, experimenters indicated to the horse that food was available without allowing them to eat it. In the positive anticipation situation, horses exhibited a lower neck position with the ears forward and upper lip advanced and went faster by increasing their stride frequency accompanied by increased global locomotor activity. In the frustration situation, horses exhibited a higher neck position with the ears backward or to the side, accompanied by ear movements and eye blinks, and interacted more with the experimenters. This study describes new possible indicators of positive anticipations and frustration in horses.

Dirt Track Surface Preparation and Associated Differences in Speed, Stride Length, and Stride Frequency in Galloping Horses.

In racehorses, the risk of musculoskeletal injury is linked to a decrease in speed and stride length (SL) over consecutive races prior to injury. Surface characteristics influence stride parameters. We hypothesized that large changes in stride parameters are found during galloping in response to dirt racetrack preparation. Harrowing of the back stretch of a half-mile dirt racetrack was altered in three individual lanes with decreasing depth from the inside to the outside. Track underlay compaction and water content were changed between days. Twelve horses (six on day 2) were sequentially galloped at a target speed of 16 ms-1 across the three lanes. Speed, stride frequency (SF), and SL were quantified with a GPS/GNSS logger. Mixed linear models with speed as covariate analyzed SF and SL, with track hardness and moisture content as fixed factors (p < 0.05). At the average speed of 16.48 ms-1, hardness (both p < 0.001) and moisture content (both p < 0.001) had significant effects on SF and SL. The largest difference in SL of 0.186 m between hardness and moisture conditions exceeded the 0.10 m longitudinal decrease over consecutive race starts previously identified as injury predictor. This suggests that detailed measurements of track conditions might be useful for refining injury prediction models.

Dynamic Stability, Symmetry, and Smoothness of Gait in People with Neurological Health Conditions.

Neurological disorders such as stroke, Parkinson's disease (PD), and severe traumatic brain injury (sTBI) are leading global causes of disability and mortality. This study aimed to assess the ability to walk of patients with sTBI, stroke, and PD, identifying the differences in dynamic postural stability, symmetry, and smoothness during various dynamic motor tasks. Sixty people with neurological disorders and 20 healthy participants were recruited. Inertial measurement unit (IMU) sensors were employed to measure spatiotemporal parameters and gait quality indices during different motor tasks. The Mini-BESTest, Berg Balance Scale, and Dynamic Gait Index Scoring were also used to evaluate balance and gait. People with stroke exhibited the most compromised biomechanical patterns, with lower walking speed, increased stride duration, and decreased stride frequency. They also showed higher upper body instability and greater variability in gait stability indices, as well as less gait symmetry and smoothness. PD and sTBI patients displayed significantly different temporal parameters and differences in stability parameters only at the pelvis level and in the smoothness index during both linear and curved paths. This study provides a biomechanical characterization of dynamic stability, symmetry, and smoothness in people with stroke, sTBI, and PD using an IMU-based ecological assessment.

Acute physiological, biomechanical, and perceptual responses of runners wearing downward-curved carbon fiber insoles.

In a randomized controlled cross-over study ten male runners (26.7 ± 4.9 years; recent 5-km time: 18:37 ± 1:07 min:s) performed an incremental treadmill test (ITT) and a 3-km time trial (3-km TT) on a treadmill while wearing either carbon fiber insoles with downwards curvature or insoles made of butyl rubber (control condition) in light road racing shoes (Saucony Fastwitch 9). Oxygen uptake, respiratory exchange ratio, heart rate, blood lactate concentration, stride frequency, stride length and time to exhaustion were assessed during ITT. After ITT, all runners rated their perceived exertion, perceived shoe comfort and perceived shoe performance. Running time, heart rate, blood lactate levels, stride frequency and stride length were recorded during, and shoe comfort and shoe performance after, the 3-km TT. All parameters obtained during or after the ITT did not differ between the two conditions [range: p = 0.188 to 0.948 (alpha value: 0.05); Cohen's d = 0.021 to 0.479] despite the rating of shoe comfort showing better scores for the control insoles (p = 0.001; d = -1.646). All parameters during and after the 3-km TT showed no differences (p = 0.200 to 1.000; d = 0.000 to 0.501) between both conditions except for shoe comfort showing better scores for control insoles (p = 0.017; d = -0.919). Running with carbon fiber insoles with downwards curvature did not change running performance or any submaximal or maximal physiological or biomechanical parameter and perceived exertion compared to control condition. Shoe comfort is impaired while running with carbon fiber insoles. Wearing carbon fiber insoles with downwards curvature during treadmill running is not beneficial when compared to running with control insoles.

Numerical study of a fish swimming in hydrokinetic turbine wake

The environmental effects of hydrokinetic turbines are still under investigation, reflecting the emerging status of this technology. This study investigates the interaction between hydrokinetic rotor wakes and fish swimming, revealing insights into fish biomechanics in complex flows and assessing the environmental implications of marine energy solutions. We conducted numerical simulations with the URANS approach and k−ω−SST turbulence closure model to predict three-dimensional turbulent flow in the OpenFOAM software. The hydrokinetic rotor wake was simulated employing the actuator line method, providing a computationally efficient alternative to full geometry simulations. For accurate replication of the motion of a fish-like tuna (Thunnus atlanticus), dynamic adaptive mesh discretization was employed. The results offer a comparative analysis of fish swimming performance within the wake rotor, particularly when immersed in the tip blade vortex, contrasted with scenarios where fish swim in undisturbed flow conditions. The analysis encompasses three-dimensional wake structures, force generation, efficiency, and equilibrium states (balancing drag and thrust) across varying Swimming numbers (Sw). Key findings include the enhanced attachment of the leading-edge vortex due to the caudal fin’s interaction with the tip blade vortex, resulting in improved auto-propulsive force production; a reduced tail stride frequency observed in fish swimming downstream of the rotor to achieve longitudinal force balance compared to unperturbed flow; and transverse hydrodynamic forces pushing fish radially away from the wake’s influence zone, potentially mitigating the risk of collision with turbine blades.