Sampling rate requirement for accurate calculation of heart rate and its variability based on the electrocardiogram.

Objective. To develop analytical formulas which can serve as quantitative guidelines for the selection of the sampling rate for the electrocardiogram (ECG) required to calculate heart rate (HR) and heart rate variability (HRV) with a desired level of accuracy.Approach. We developed analytical formulas which relate the ECG sampling rate to conservative bounds on HR and HRV errors: (i) one relating HR and sampling rate to a HR error bound and (ii) the others relating sampling rate to HRV error bounds (in terms of root-mean-square of successive differences (RMSSD) and standard deviation of normal sinus beats (SDNN)). We validated the formulas using experimental data collected from 58 young healthy volunteers which encompass a wide HR and HRV ranges through strenuous exercise.Main results. The results strongly supported the validity of the analytical formulas as well as their tightness. The formulas can be used to (i) predict an upper bound of inaccuracy in HR and HRV for a given sampling rate in conjunction with HR and HRV as well as to (ii) determine a sampling rate to achieve a desired accuracy requirement at a given HR or HRV (or its range).Significance. HR and its variability (HRV) derived from the ECG have been widely utilized in a wide range of research in physiology and psychophysiology. However, there is no established guideline for the selection of the sampling rate for the ECG required to calculate HR and HRV with a desired level of accuracy. Hence, the analytical formulas may guide in selecting sampling rates for the ECG tailored to various applications of HR and HRV.

Whole body mass estimates and error propagation in countermovement jump: a simulated error study.

High-velocity actions are central to clinical and athletic performance, with jumping used to assess outcomes in sports medicine. Ground reaction force (GRF)-based methods are the standard for computing jump characteristics, but require mass estimation and GRF integration, potentially resulting in mass errors which influence outcomes. This study investigated how simulated mass errors influenced the centre of mass (CoM) trajectory during a countermovement jump. The mass was estimated from the static GRF, and simulated errors were added or subtracted to the mass. The CoM trajectory with simulated mass errors was computed using the GRF-based method to investigate mass mis-estimation's influence on jump height. A regression model indicated that, for a 1 kg mass change, there was a 7.7 cm jump height change, and the jump height differed by 11.5 ± 0.4 cm from the maximum to minimum error. A 2-way ANOVA identified significant height differences between the starting position, and landing, or final position with mass errors of ± 0.2 or ± 0.4 kg. These results reveal that small mass errors may produce inaccurate conclusions regarding performance changes, and that errors may propagate throughout the jump trajectory. Caution may be necessary when using GRF-based methods to compute jump height as a power proxy.

Dorsiflexion shoes affect joint-level landing mechanics related to lower extremity injury risk in females.

Athletic shoes that induce dorsiflexion in standing can improve jump height compared to traditional athletic shoes that induce plantarflexion, but it is unknown if dorsiflexion shoes (DF) also affect landing biomechanics associated with lower extremity injury risk. Thus, the purpose of this study was to investigate if DF adversely affect landing mechanics related to patellofemoral pain and anterior cruciate ligament injury risk compared to neutral (NT) and plantarflexion (PF) shoes. Sixteen females (21.65 ± 4.7 years, 63.69 ± 14.3 kg, 1.60 ± 0.05 m) performed three maximum vertical countermovement jumps in DF (-1.5°), NT (0°) and PF (8°) shoes as 3D kinetics and kinematics were recorded. One-way repeated-measures ANOVAs revealed peak vertical ground reaction force, knee abduction moment and total energy absorption were similar between conditions. At the knee, peak flexion and joint displacement were lower in DF and NT, while relative energy absorption was greater in PF (all p < .01). Conversely, relative ankle energy absorption was greater in DF and NT compared to PF (p < .01). Both DF and NT induce landing patterns that may increase strain on passive structures in the knee, emphasising the need for landing mechanics to be considered when testing footwear as gains in performance could come at the cost of injury risk.

Prediction of knee adduction moment using innovative instrumented insole and deep learning neural networks in healthy female individuals.

BACKGROUND: The knee adduction moment, a biomechanical risk factor of knee osteoarthritis, is typically measured in a gait laboratory with expensive equipment and inverse dynamics modeling software. We aimed to develop a framework for a portable knee adduction moment estimation for healthy female individuals using deep learning neural networks and custom instrumented insole and evaluated its accuracy compared to the standard inverse dynamics approach. METHODS: Feed-forward, convolutional, and recurrent neural networks were applied to the data extracted from five piezo-resistive force sensors attached to the insole of a shoe. RESULTS: All models predicted knee adduction moment variables during walking with high correlation coefficients, r > 0.72, and low root mean squared errors (RMSE), ranging from 0.5% to 1.2%. The convolutional neural network is the most accurate predictor of average knee adduction moment (r = 0.96; RMSE = 0.5%) followed by the recurrent and feed-forward neural networks. CONCLUSION: These findings and the methods presented in the current study are expected to facilitate a cost-effective clinical analysis of knee adduction moment for healthy female individuals and to facilitate future research on prediction of other biomechanical risk factors using similar methods.

Anthropometric, physical activity, and psychological characteristics of Korean adults with and without developmental coordination disorder (DCD).

Developmental Coordination Disorder (DCD), also known as Dyspraxia, is characterized by movement difficulties in individuals without discernible neurological disorders or identifiable medical conditions. Previous studies from various countries have highlighted disparities in anthropometric, physical activity, and psychological characteristics between children diagnosed with DCD and their typically developing (TD) peers. These differences are influenced by sociocultural norms and geographical locations. However, little attention has been given to scrutinizing analogous differences in adult populations, particularly within Republic of Korea. This study aims to address this knowledge gap by employing a battery of questionnaires to assess anthropometric, physical activity, and psychological traits in a cohort of 377 Korean adults, encompassing those with DCD (n = 54) alongside TD counterparts (n = 323). It was hypothesized that Korean adults with DCD would exhibit higher body mass index and lower ratings in physical activity and psychological characteristics than TD, consistent with the previous studies performed in other countries on children. The results showed no statistically significant differences between the DCD and TD groups in anthropometric characteristics such as weight (kg), height (cm), and body mass index. The prevalence of walking and biking for daily commuting in daily routines within Korean society might have contributed to the mitigation of anthropometric among individuals with/without DCD. Statistically significant differences were found in physical activity levels at work and recreational settings, as shown in physical activity scores and duration. The DCD group also displayed lower scores across several psychological characteristics, including exercise adherence, intrinsic motivation, self-efficacy, physical self-concept, exercise expectations, and intrinsic regulation. These findings underscore the necessity of incorporating sociocultural dynamics when investigating anthropometric, physical activity, and psychological characteristics in adults with DCD. Their perceived difficulties in fine motor skills were also significantly poor than TD. Future research studies are warranted to elucidate the underlying mechanisms driving the observed patterns in this study, thus contributing to a more nuanced comprehension of how DCD manifests within specific sociocultural contexts.

Interpersonal motor synergy: coworking strategy depends on task constraints.

We investigated the role of task constraints on interpersonal interactions. Twenty-one pairs of coworkers performed a finger force production task on force sensors placed at two ends of a seesaw-like apparatus and matched a combined target force of 20 N for 23 s over 10 trials. There were two experimental conditions: 1) FIXED: the seesaw apparatus was mechanically held in place so that the only task constraint was to match the 20 N resultant force, and 2) MOVING: the lever in the apparatus was allowed to rotate freely around its fulcrum, acting like a seesaw, so an additional task constraint to (implicitly) balance the resultant moment was added. We hypothesized that the additional task constraint of moment stabilization imposed on the MOVING condition would deteriorate task performance compared with the FIXED condition; however, this was rejected, as the performance of the force matching task was similar between two conditions. We also hypothesized that the central nervous systems (CNSs) would employ distinct coworking strategies or interpersonal motor synergy (IPMS) between conditions to satisfy different task constraints, which was supported by our results. Negative covariance between coworker's forces in the FIXED condition suggested a force stabilization strategy, whereas positive covariance in the MOVING condition suggested a moment stabilization strategy, implying that independent CNSs adopt distinct IPMSs depending on task constraints. We speculate that in the absence of a central neural controller, shared visual and mechanical connections between coworkers may suffice to trigger modulations in the cerebellum of each CNS to satisfy competing task constraints.NEW & NOTEWORTHY To the best of our knowledge, this is the first study to investigate the coworking behavior or IPMS when an additional task constraint is imposed. Our proposed analytical framework quantifies IPMS and allows for investigating variability in offline (i.e., across multiple repetitions) and online (i.e., across time) control, which is novel in coworking research. Understanding variability while performing a task is essential, as repeating a task is not always possible, as in therapeutic contexts.

Roller Massage Prior to Running Does Not Affect Gait Mechanics in Well-Trained Runners.

CONTEXT: Understanding if roller massage prior to a run can mitigate fatigue-related decrements in muscle force production during prolonged running is important because of the association between fatigue and running-related injury. OBJECTIVE: The authors investigated whether a bout of roller massage prior to running would (1) mitigate fatigue-related increases in vertical average load rate and free moment of the ground reaction force of running and (2) mitigate decreases in maximal countermovement jump height. DESIGN: Repeated-measures study. SETTING: Laboratory. PARTICIPANTS: A total of 14 recreational endurance athletes (11 men and 3 women) volunteered for the study. INTERVENTIONS: A 12.5-minute foam roller protocol for the lower extremities and a fatiguing 30-minute treadmill run. MAIN OUTCOME MEASURES: Vertical average load rate, free moment, and maximal jump height before (PRE) and after (POST) the fatiguing treadmill run on separate experimental days: once where participants sat quietly prior to the fatiguing run (REST) and another where the foam roller protocol was performed prior to the run (ROLL). RESULTS: A 2-way multiple analysis of variance found no significant differences in vertical average load rate, free moment, and jump height between PRE/POST times in both REST/ROLL conditions. CONCLUSIONS: The authors concluded that recreational endurance athletes maintain running mechanics and jump performance after a fatiguing run regardless of prerun roller massage and may not rely on prerun roller massage as a form of injury prevention.

Small changes in ball position at address cause a chain effect in golf swing.

The purpose of this study was to investigate how the ball position along the mediolateral (M-L) direction of a golfer causes a chain effect in the ground reaction force, body segment and joint angles, and whole-body centre of mass during the golf swing. Twenty professional golfers were asked to complete five straight shots for each 5 different ball positions along M-L: 4.27 cm (ball diameter), 2.14 cm (ball radius), 0 cm (reference position at preferred ball position), - 2.14 cm, and - 4.27 cm, while their ground reaction force and body segment motions were captured. The dependant variables were calculated at 14 swing events from address to impact, and the differences between the ball positions were evaluated using Statistical Parametric Mapping. The left-sided ball positions at address showed a greater weight distribution on the left foot with a more open shoulder angle compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. These trends disappeared during the backswing and reappeared during the downswing. The whole-body centre of mass was also located towards the target for the left-sided ball positions throughout the golf swing compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. We have concluded that initial ball position at address can cause a series of chain effects throughout the golf swing.

Vibration Suppression of a Composite Prosthetic Foot Using Piezoelectric Shunt Damping: Implications to Vibration-Induced Cumulative Trauma.

OBJECTIVE: Energy-storage-and-return (ESAR) prosthetic feet have improved amputee mobility due to their efficient conversion of strain energy to mechanical work. However, this efficiency is typically achieved using light-weight, high-stiffness materials, which generate high-frequency vibrations that are potentially injurious if transmitted to biological tissues. To reduce the vibration which may cause cumulative tissue trauma, high-frequency vibration suppression by piezoelectric shunt damping patches on a commercial ESAR foot was evaluated. METHODS: Two patches with either passive or active shunt circuits were placed on the foot to investigate vibration suppression during experimental tests where a plastic hammer was used to hit a clamped ESAR foot on the free end. Prosthesis bending moments at each modal frequency were obtained by finite element methods to identify piezoelectric patch placement. RESULTS: Both shunt circuits decreased vibration amplitudes at specific modes better than the no shunt case, but also increased the amplitude at specific frequencies. The vibration suppression performance of the active shunt circuit deteriorated at the second mode, while the vibration suppression performance of the passive shunt circuit deteriorated at all frequencies above the third mode. CONCLUSIONS: These results indicate piezoelectric shunt patches may be a viable strategy for decreasing vibrations of an ESAR foot, with active methods more efficient at suppressing high-frequency vibrations. Additional research is necessary to fine-tune the method for maximal vibration suppression. SIGNIFICANCE: Overall, this study indicates that high-frequency vibration suppression is possible using piezoelectric patches, possibly decreasing the cumulative tissue damage that may occur with repetitive exposure to vibration.

Dance training improves the CNS's ability to utilize the redundant degrees of freedom of the whole body.

Professional dancers demonstrate an amazing ability to control their balance. However, little is known about how they coordinate their body segments for such superior control. In this study, we investigated how dancers coordinate body segments when a physical perturbation is given to their body. A custom-made machine was used to provide a short pulling impulse at the waist in the anterior direction to ten dancers and ten non-dancers. We used Uncontrolled Manifold analysis to quantify the variability in the task-relevant space and task-irrelevant space within the multi-dimensional space made up of individual segments' centers of mass with a velocity adjustment. The dancers demonstrated greater utilization of redundant degrees of freedom (DoFs) supported by the greater task-irrelevant variability as compared to non-dancers. These findings suggest that long-term specialized dance training can improve the central nervous system's ability to utilize the redundant DoFs in the whole-body system.

Sensory-to-Motor Overflow: Cooling Foot Soles Impedes Squat Jump Performance.

Evidence from recent studies on animals and humans suggest that neural overflow from the primary sensory cortex (S1) to the primary motor cortex (M1) may play a critical role in motor control. However, it is unclear if whole-body maximal motor tasks are also governed by this mechanism. Maximum vertical squat jumps were performed by 15 young adults before cooling, then immediately following a 15-min cooling period using an ice-water bath for the foot soles, and finally immediately following a 15-min period of natural recovery from cooling. Jump heights were, on average, 3.1 cm lower immediately following cooling compared to before cooling (p = 3.39 × 10-8) and 1.9 cm lower following natural recovery from cooling (p = 0.00124). The average vertical ground reaction force (vGRF) was also lower by 78.2 N in the condition immediately following cooling compared to before cooling (p = 8.1 × 10-5) and 56.7N lower following natural recovery from cooling (p = 0.0043). The current study supports the S1-to-M1 overflow mechanism in a whole-body dynamic jump.

Standardized Lab Shoes Do Not Decrease Loading Rate Variability in Recreational Runners.

Studies of running mechanics often use a standardized lab shoe, ostensibly to reduce variance between subjects; however, this may induce unnatural running mechanics. The purpose of this study was to compare the step rate, vertical average loading rate, and ground contact time when running in standardized lab shoes versus participants' normal running shoes. Ground reaction forces were measured while the participants ran overground in both shoe conditions at a self-selected speed. The Student's t-test revealed that the vertical average loading rate magnitude was smaller in lab shoes versus normal shoes (42.09 [11.08] vs 47.35 [10.81] body weight/s, P = .013), while the step rate (170.92 [9.43] vs 168.98 [9.63] steps/min, P = .053) and ground contact time were similar (253 [25] vs 251 [20] ms, P = .5227) and the variance of all outcomes was similar in lab shoes versus normal shoes. Our results indicate that using standardized lab shoes during testing may underestimate the loads runners actually experience during their typical mileage.

Inter-dependence between mathematically independent variability components in human multi-finger force control.

In human movement control, inherent error or uncertainty in the controller, motor system, and sensory system causes variability in motor outcomes. Previous studies have suggested different methods to quantify and examine independent components of the motor variability of motor outputs in a redundant motor system. While these motor variability components are mathematically independent, it is unknown if these components are behaviorally independent among subjects. The aim of this study was to investigate inter-relations between mathematically independent motor variability components in multi-finger force control among subjects. Nineteen healthy subjects performed two tasks, producing a constant force and a sinusoidal force for 12 s over 12 trials. We used the hierarchical variability decomposition (HVD) model to quantify mathematically independent variability components, i.e., online task-relevant variance (onTRV), online task-irrelevant variance (onTIV), offline task-relevant variance (offTRV), and offline task-irrelevant variance (offTIV) for each subject. The correlation analysis performed among all subjects showed that online and offline motor variability components were positively correlated, while task-relevant and -irrelevant variability components were not. The results indicate that these mathematically independent motor variability components existing in multi-finger force space are dependently scaled among subjects, more noticeably between online and offline controls, suggesting a non-independent behavioral relationship between these mathematically independent components among subjects.

Fast Running Does Not Contribute More to Cumulative Load than Slow Running.

PURPOSE: As running speed increases there are concomitant changes in loads associated with tibial stress fracture risk. Runners often include multiple speeds in their training, but the effect of speed distribution on load accumulation is unknown. We studied how running at different proportions of speed within a given running distance affects the cumulative loading of the vertical average loading rate, cumulative peak absolute tibial free moment, and cumulative peak axial tibial load. These loads were compared between two proportions of speed: running all distance at normal self-selected speed, and running the same distance at a combination of slow/fast speeds with the same average speed as normal. Also, the contributions of slow and fast running to the combined condition were compared. METHODS: Forty-three recreational runners (age, 18-49 yr; 29 female, 14 male) ran around a 50-m indoor track for three laps each at self-selected slow, normal, and fast speeds. Per-step peak loads and cumulative loads per kilometer were calculated at each speed and for each speed distribution, respectively. RESULTS: Only cumulative vertical average loading rate was lower at normal speed compared with the slow/fast speed combination. The contribution of fast speed running to cumulative tibial load was less than the contribution of slow speed running. CONCLUSIONS: Running at a combination of slow and fast speeds, rather than a single moderate speed, increased cumulative vertical average loading rate but not cumulative tibial load or free moment. Fast running can be included in a training program without necessarily increasing the cumulative load. Total distance and average speed may not be sufficient information to estimate cumulative load from running training.

Amputee Locomotion: Joint Moment Adaptations to Running Speed Using Running-Specific Prostheses after Unilateral Transtibial Amputation.

OBJECTIVE: The objective of this study was to investigate three-dimensional lower extremity joint moment differences between limbs and speed influences on these differences in individuals with lower extremity amputations using running-specific prostheses. DESIGN: Eight individuals with unilateral transtibial amputations and 8 control subjects with no amputations ran overground at three constant velocities (2.5, 3.0, and 3.5 m/sec). A 2 × 2 × 3 (group × leg × speed) repeated-measures analysis of variance with Bonferroni adjustments determined statistical significance. RESULTS: The prosthetic limb generated significantly greater peak ankle plantarflexion moments and smaller peak ankle varus, knee stance extension, knee swing flexion, knee internal rotation, hip stance flexion, hip swing flexion, hip swing extension, hip valgus, and hip external rotation moments than the intact limb did. The intact limb had greater peak hip external rotation moments than control limbs did, but all other peak moments were similar between these limbs. Increases in peak hip stance and knee swing flexion moments associated with speed were greater in the intact limb than in the prosthetic limb. CONCLUSION: Individuals with amputation relied on the intact limb more than the prosthetic limb to run at a particular speed when wearing running-specific prostheses, but the intact joints were not overloaded relative to the control limbs.

Intra-auditory integration between pitch and loudness in humans: Evidence of super-optimal integration at moderate uncertainty in auditory signals.

When a person plays a musical instrument, sound is produced and the integrated frequency and intensity produced are perceived aurally. The central nervous system (CNS) receives defective afferent signals from auditory systems and delivers imperfect efferent signals to the motor system due to the noise in both systems. However, it is still little known about auditory-motor interactions for successful performance. Here, we investigated auditory-motor interactions as multi-sensory input and multi-motor output system. Subjects performed a constant force production task using four fingers in three different auditory feedback conditions, where either the frequency (F), intensity (I), or both frequency and intensity (FI) of an auditory tone changed with sum of finger forces. Four levels of uncertainty (high, moderate-high, moderate-low, and low) were conditioned by manipulating the feedback gain of the produced force. We observed performance enhancement under the FI condition compared to either F or I alone at moderate-high uncertainty. Interestingly, the performance enhancement was greater than the prediction of the Bayesian model, suggesting super-optimality. We also observed deteriorated synergistic multi-finger interactions as the level of uncertainty increased, suggesting that the CNS responded to increased uncertainty by changing control strategy of multi-finger actions.

Aging differentially affects online control and offline control in finger force production.

Human central nervous system (CNS) undergoes neurological changes during the aging process, leading to declines in hand and finger functions. Previous studies have shown that the CNS can independently process multi-finger force control and moment of force control. However, if both force and moment control are simultaneously imposed by motor task constraints, the CNS needs to resolve competing interests of generating negative and positive covariances between fingers, respectively, which causes "conflict of interest or COI". Here, we investigated how aging affects the CNS's abilities to solve COI through a new experimental paradigm. Both elderly and young subjects performed a constant force production task using index and middle fingers under two conditions, multi-finger pressing with no COI and with COI. We found that the elderly increased variance of a virtual finger (VF: an imagined finger producing the same mechanical effect as both fingers together) in time-to-time basis (i.e. online control), while increasing covariance between individual fingers (IF) forces in trial-to-trial basis (i.e. offline control) with COI than no COI. Aging affects the CNS's abilities to solve COI by deteriorating VF actions in online control and IF actions in offline control.

Wrist Resistance Training Improves Motor Control and Strength.

Chu, E, Kim, Y-S, Hill, G, Kim, YH, Kim, CK, and Shim, JK. Wrist resistance training improves motor control and strength. J Strength Cond Res 32(4): 962-969, 2018-The aim of this study was to investigate the effects of a 6-week direction-specific resistance training program on isometric torque control and isokinetic torque strength of the wrist joint. Nineteen subjects were randomly assigned to either the wrist training group (n = 9) or the control group (n = 10). The training group performed wrist exercises in 6 directions (flexion, extension, pronation, supination, radial deviation, and ulnar deviation), whereas the control group did not. Data were collected on the isometric torque control, 1-repetition maximum (1RM) strength, and isokinetic maximum torque (angular velocity of 60° per second wrist movements) before and after 6 weeks of resistance training and at 2-week intervals during training. The training group showed significant decreases in isometric torque control error in all 6 directions after 2 weeks of resistance training, whereas the control group did not show significant increase or decrease. After 4 weeks of training, the training group showed significant increases in maximum strength in all 6 directions as assessed by 1RM strength and isokinetic strength tests, whereas the control group did not show any statistically significant changes. This study shows that motor control significantly improves within the first 2 weeks of resistance training, whereas the wrist strength significantly improves within the first 4 weeks of resistance training. Based on the findings of this study, coaches and trainers should consider wrist resistance training to improve athletes' muscular strength and control of the wrist muscles.

Examining impairment of adaptive compensation for stabilizing motor repetitions in stroke survivors.

The hand, one of the most versatile but mechanically redundant parts of the human body, suffers more and longer than other body parts after stroke. One of the rehabilitation paradigms, task-oriented rehabilitation, encourages motor repeatability, the ability to produce similar motor performance over repetitions through compensatory strategies while taking advantage of the motor system's redundancy. The previous studies showed that stroke survivors inconsistently performed a given motor task with limited motor solutions. We hypothesized that stroke survivors would exhibit deficits in motor repeatability and adaptive compensation compared to healthy controls in during repetitive force-pulse (RFP) production tasks using multiple fingers. Seventeen hemiparetic stroke survivors and seven healthy controls were asked to repeatedly press force sensors as fast as possible using the four fingers of each hand. The hierarchical variability decomposition model was employed to compute motor repeatability and adaptive compensation across finger-force impulses, respectively. Stroke survivors showed decreased repeatability and adaptive compensation of force impulses between individual fingers as compared to the control (p < 0.05). The stroke survivors also showed decreased pulse frequency and greater peak-to-peak time variance than the control (p < 0.05). Force-related variables, such as mean peak force and peak force interval variability, demonstrated no significant difference between groups. Our findings indicate that stroke-induced brain injury negatively affects their ability to exploit their redundant or abundant motor system in an RFP task.

Amputee locomotion: Frequency content of prosthetic vs. intact limb vertical ground reaction forces during running and the effects of filter cut-off frequency.

Compared to intact limbs, running-specific prostheses have high resonance non-biologic materials and lack active tissues to damp high frequencies. These differences may lead to ground reaction forces (GRFs) with high frequency content. If so, ubiquitously applying low-pass filters to prosthetic and intact limb GRFs may attenuate veridical high frequency content and mask important and ecologically valid data from prostheses. To explore differences in frequency content between prosthetic and intact limbs we divided signal power from transtibial unilateral amputees and controls running at 2.5, 3.0, and 3.5m/s into Low (<10Hz), High (10-25Hz), and Non-biologic (>25Hz) frequency bandwidths. Faster speeds tended to reduce the proportion of signal power in the Low bandwidth while increasing it in the High and Non-biologic bandwidths. Further, prostheses had lower proportions of signal power at the High frequency bandwidth but greater proportions at the Non-biologic bandwidth. To evaluate whether these differences in frequency content interact with filter cut-offs and alter results, we filtered GRFs with cut-offs from 1 to 100Hz and calculated vertical impact peak (VIP). Changing cut-off had inconsistent effects on VIP across speeds and limbs: Faster speeds had significantly larger changes in VIP per change in cut-off while, compared to controls, prosthetic limbs had significantly smaller changes in VIP per change in cut-off. These findings reveal differences in GRF frequency content between prosthetic and intact limbs and suggest that a cut-off frequency that is appropriate for one limb or speed may be inappropriate for another.