Background: Experts of the Krav Maga (KM) self-defense system propose that KM techniques are based on simple body movements which are suggested to be learned rapidly and retained. This study investigated the acquisition, retention, and further improvement with additional training of two KM strike techniques among novice female practitioners: straight punch and defensive kick. Methods: Sixteen healthy females (age: 23 ± 3.7 years) without any previous martial arts/self-defense experience volunteered to participate. All participants received an initial 30-min instruction session (AQ), taught by a certified KM instructor, where each technique was deconstructed into three checkpoints (defined as a component of the entire movement) for learning. Participants were divided into two groups, one of which received additional training. Several kinematic and kinetic measures were recorded at four timepoints: immediately before AQ, immediately after AQ, 5 days after AQ, and 12 days after AQ. Results: Results suggest that both techniques were learned rapidly, as checkpoint performance was significantly improved after AQ. Kick velocity and impact force also increased significantly after AQ; however, these measures did not change after AQ for the punch technique. Additional training did not improve either punch or kick performance beyond that learned during AQ. Conclusion: The findings from this study suggest that a single training session may be sufficient to learn and retain KM strike techniques relatively permanently; and the acquisition of the kick technique may lead to concomitant improvements in kick velocity and impact force.

Stride-to-stride fluctuations during walking reflect age-related changes in gait adaptability and are estimated with nonlinear measures that confine data collection to controlled settings. Smartphones, with their embedded accelerometers, may provide accessible gait analysis throughout the day. This study investigated age-related differences in linear and nonlinear gait measures estimated from a smartphone accelerometer (SPAcc) in an unconstrained, free-living environment. Thirteen young adults (YA) and 11 older adults (OA) walked within a shopping mall with a SPAcc placed in their front right pants pocket. The inter-stride interval, calculated as the time difference between ipsilateral heel contacts, was used for dependent measures calculations. One-way repeated-measures analysis of variance revealed significant (p < 0.05) age-related differences (mean: YA, OA) for stride-time standard deviation (0.04 s, 0.05 s) and coefficient of variation (3.47%, 4.16%), sample entropy (SaEn) scale 1 (1.70, 1.86) and scale 3 (2.12, 1.80), and statistical persistence decay (31 strides, 23 strides). The fractal scaling index was not different between groups (0.93, 0.95), but exceeded those typically found in controlled settings, suggesting an upregulation in adaptive behaviour likely to accommodate the increased challenge of free-living walking. These findings support the SPAcc as a viable telehealth instrument for remote monitoring of gait dynamics, with implications for unsupervised fall-risk assessment.

Balance-correcting responses are fast, accurate, and functionally- and directionally-specific. However, there remains a lack of clarity in the literature as to how balance-correcting responses are organized, perhaps due to use of various perturbation methods. This study investigated the differences in neuromuscular organization of balance-correcting responses induced with platform-translation (PLAT) and upper body cable-pull (PULL) methods. Healthy males (n = 15; age: 24.3 ± 3.0 years) underwent unexpected forward and backward PLAT and PULL perturbations of equivalent intensity. EMG of leg, thigh, and trunk anterior and posterior muscles was recorded bilaterally during forward-stepping trials. Muscle activation latencies were calculated with respect to perturbation initiation. Repeated measures ANOVAs tested for differences in muscle activation latencies between perturbation methods and body sides (anterior/posterior muscles, swing/stance limb sides); Holm-Bonferroni sequentially rejective procedure adjusted alpha during multiple comparisons. Anterior muscle activation latencies were similar between methods (∼210 ms). During PLAT trials, posterior muscles demonstrated symmetrical distal-proximal activation between 70 ms and 260 ms, bilaterally. During PULL trials, stance-limb side posterior muscles demonstrated proximal-distal activation 70-130 ms; the activation latencies (∼80 ms) were not different between the stance-limb side posterior muscles. Previous examinations of method comparisons have examined results across publications, and generally have not accounted for different stimulus characteristics. This study revealed markedly different neuromuscular organization of balance-correcting responses to two different perturbation methods that utilized, importantly, equivalent perturbation intensity. Interpretation of functional balance recovery responses requires clear understanding of the intensity and nature of the perturbation.

This scoping review investigated the definitions, assessment methods, and current applications of varus thrust (VT) in knee osteoarthritis (OA). Five databases (MEDLINE, EMBASE, CINAHL, SPORTDiscus, and Web of Science Core Collection) were searched in this scoping review for studies assessing VT during walking in adults with knee OA using the terms “varus” and “lateral” in proximity to thrust. Data were extracted and categorized by study characteristics (OA sample, publication year, design, and aim) and VT assessment protocol (method and definition). A total of 63 studies were included, examining 12,569 individuals with knee OA using visual (n ​= ​24), optical motion capture (n ​= ​27), or inertial/wearable sensor (n ​= ​19) methods. Designs included prospective, experimental, cross-sectional, and case series. VT was most often assessed to examine disease severity, progression, surgical outcomes, and symptom associations. Visual VT was commonly defined as dynamic worsening or abrupt onset of varus alignment during weight acceptance. Optical motion capture commonly measured VT as frontal plane knee excursion from foot contact to mid-stance, while inertial methods typically used peak lateral tibial acceleration or angular velocity. Despite growing research interest in VT, inconsistent definitions and measurement protocols limit comparability across studies and hinder broader adoption. Greater standardization and validation are needed to clarify its potential clinical utility in knee OA.