Understanding the changes in running mechanics caused by fatigue is essential to assess its impact on athletic performance. Changes in running biomechanics after constant speed conditions are well documented, but the adaptive responses after a maximal incremental test are unknown. We compared the spatiotemporal, joint kinematics, elastic mechanism, and external work parameters before and after a maximal incremental treadmill test. Eighteen recreational runners performed 2-minute runs at 8 km·h⁻¹ before and after a maximal incremental test on a treadmill. Kinematics, elastic parameters, and external work were determined using the OpenCap and OpenSim software. We did not find differences in spatiotemporal parameters and elastic parameters (mechanical work, ankle, and knee motion range) between premaximal and postmaximal test conditions. After the maximal test, the runners flexed their hips more at contact time (19.4°–20.6°, P = .013) and presented a larger range of pelvis rotation at the frontal plane (10.3°–11.4°, P = .002). The fatigue applied in the test directly affects pelvic movements; however, it does not change the lower limb motion or the spatiotemporal and mechanical work parameters in recreational runners. A larger frontal plane motion of the pelvis deserves attention due to biomechanical risk factors associated with injuries.

Purpose: In the natural environment, humans must continuously negotiate irregular and unpredictable terrain. Recently, the poles have been extensively used during trial running events. However, we know little about how humans adjust posture and bilateral coordination to use poles in irregular terrain. Here, we compared kinematics, bilateral coordination and perceptual responses between regular (compact dust) and irregular terrain (medium-length grass) during running at preferred speed with and without poles. Methods: In this transversal observational study, thirteen young healthy adults (8 men; mean ± SD; age 29.1 ± 8.0 years, body mass 76.8 ± 11.4 kg; height 1.75 ± 0.08 m) were evaluated during running at a self-selected comfortable speed with and without poles on regular and irregular terrains. Results: Our results show that, despite more flexed pattern on lower-limb joints at irregular terrain, the usage of poles was not enough to re-stabilize the bilateral coordination. Also, the perceived exertion was impaired adding poles to running, probably due to more complex movement pattern using poles in comparison to free running, and the invariance in the bilateral coordination. Conclusion: Besides the invariability of usage poles on bilateral coordination and lower-limb kinematics, the runners seem to prioritize postural stability over lower limb stiffness when running in medium-length grass given the larger range of ankle and knee motion observed in irregular terrain. Further investigations at rougher/hilly terrains will likely provide additional insights into the neuromotor control strategies used to maintain the stability and on perceptual responses using poles during running.

Marker-based motion capture is the gold standard for 3-dimensional gait analysis but is expensive and largely confined to specialized laboratories. Smartphone-based markerless tools such as OpenCap could scale gait assessment, yet their validity and repeatability during treadmill walking and running remain unclear. We evaluated agreement and within-session repeatability between OpenCap and motion capture during treadmill walking (4 km·h ⁻¹ ) and running (8 and 14 km·h ⁻¹ ) in 10 healthy adults, recorded simultaneously with both systems. We computed spatiotemporal variables, sagittal hip/knee/ankle angle waveforms and range of motion, and center-of-mass displacement waveforms and range of motion. Agreement was assessed with Bland–Altman, intraclass correlation coefficients, Pearson r , and root mean square error; repeatability with trial-to-trial SD, coefficient of variation, and waveform variability index (GaitSD). Spatiotemporal metrics showed bias close to 0 and very strong associations ( r ≥ .96), with small minimum detectable changes (eg, ≤0.01 m for stride length and ≤0.03 s for temporal variables). Sagittal range of motion showed good-to-excellent reliability (bias: ≈−4.5° to 2.9°, intraclass correlation coefficients = .76–.93). Waveform root mean square error was ≈1° to 4° for joint angles and ≈0.1 to 0.5 cm for center of mass, and statistical parametric mapping indicated only localized differences. Repeatability and GaitSD were comparable between systems across variables and speeds. Under controlled treadmill conditions, OpenCap showed comparable performance and repeatability metrics to motion capture.

Purpose: Loss of digital leverage can severely disrupt inverted pendulum mechanics and alter how mechanical work is distributed during walking. The biomechanical efficacy of prosthetic footwear in individuals with bilateral toe amputation remains poorly understood. This exploratory single-case study quantified the effects of custom prosthetic footwear on pendular recovery, mechanical work distribution, and functional mobility in a 52-year-old male with complete bilateral digital amputation (metatarsals preserved), while evaluating intervention effects relative to concurrent walking speed changes. Methods: Three-dimensional kinematic data were collected during barefoot and prosthetic footwear walking across 13 consecutive stride cycles (7 barefoot, 6 shod). Functional speed restoration was evaluated via the Locomotor Rehabilitation Index (LRI). Unadjusted condition differences were evaluated using Hedges’ g with bootstrap confidence intervals. To isolate intervention effects from walking velocity, a single-case multiple linear regression model incorporating a first-order autoregressive error structure [AR(1)] evaluated speed-adjusted intervention effects (β₁) centered at grand mean speed (1.14 m/s). Results: Walking speed increased substantially from 0.88 ± 0.08 m/s barefoot (range: 0.76–0.98 m/s) to 1.45 ± 0.05 m/s with footwear (range: 1.38–1.52 m/s; Hedges’ g = 7.78), restoring size-controlled functional mobility (LRI increased from 57% to 94%). Unadjusted comparisons showed increases in pendular recovery (39% to 47%, g = 4.03); external mechanical work, Wext (0.460 to 0.608 J/kg/m, g = 4.85); forward work, Wf (0.286 to 0.627 J/kg/m, g = 5.92); and internal work, Wint (0.194 to 0.225 J/kg/m, g = 3.12). However, because walking speeds were distinctly separated with no overlap between conditions, parameter estimates at the mean speed rely on model extrapolation. When controlling for instantaneous stride speed via AR(1) regression (autocorrelation ρ = 0.38), speed-adjusted condition effects were non-significant for Wext (β₁ = +0.085 J/kg/m, p = 0.265), Wf (β₁ = +0.051 J/kg/m, p = 0.296), Wint (β₁ = −0.007 J/kg/m, p = 0.680), and pendular recovery (β₁ = +0.10%, p = 0.981), which is consistent with strong velocity dependence rather than intrinsic shifts in mechanical efficiency at a given speed. Vertical external work demonstrated a statistical trend toward elevation in the prosthetic condition (β₁ = +0.162 J/kg/m, p = 0.062), which may reflect compensatory vertical body center of mass redirection to compensate for reduced distal forefoot lever propulsion during rollover. Conclusions: Prosthetic footwear substantially enhances functional gait mobility by enabling velocity restoration toward Froude-based optimal speed, although independent footwear and velocity effects cannot be fully decoupled without observations at overlapping speeds.

Background: In dual-task (DT) conditions, individuals must walk while simultaneously engaging in cognitive or motor tasks, which impacts gait performance, especially in older adults and individuals with Parkinson’s disease (PD). Gait impairments in PD under DT conditions have implications for intersegmental coordination. Research question: Intersegmental coordination and gait biomechanics during the DTs were compared between people with PD and older adults. Methods: Thirty-two individuals (16 PD, H&Y 1–3; and 16 older adults) participated in this study and were asked to walk under the following self-selected conditions: single task, DT with a math component, and texting on a cell phone. Spatiotemporal, angular, and intersegmental coordination data were collected using a markerless motion analysis system (OpenCap). Results: Dual-task conditions significantly affected spatiotemporal and kinematic variables, as well as intersegmental coordination. A significant task effect was observed for thigh–shank coordination, whereas no significant group effect was found for the main coordination outcomes. Significance: Significant task effects were observed for intersegmental coordination (thigh–shank CRP), with no significant group differences. The concurrent demands of processing visual and motor information for texting and walking lead to significant reductions in gait speed and lower limb movement, as well as altered intersegmental coordination, with task demands rather than disease status being the primary driver of coordination changes.