In athletics sprint events, the block start performance can be fundamental to the outcome of a race. This Systematic Review aims to identify biomechanical factors of critical importance to the block start and subsequent first two steps performance. A systematic search of relevant English-language articles was performed on three scientific databases (PubMed, SPORTDiscus, and Web of Science) to identify peer-reviewed articles published until June 2021. The keywords “Block Start”, “Track and Field”, “Sprint Running”, and “Kinetics and Kinematics” were paired with all possible combinations. Studies reporting biomechanical analysis of the block start and/or first two steps, with track and field sprinters and reporting PB100m were sought for inclusion and analysis. Thirty-six full-text articles were reviewed. Several biomechanical determinants of sprinters have been identified. In the “Set” position, an anthropometry-driven block setting facilitating the hip extension and a rear leg contribution should be encouraged. At the push-off, a rapid extension of both hips and greater force production seems to be important. After block exiting, shorter flight times and greater propulsive forces are the main features of best sprinters. This systematic review emphasizes important findings and recommendations that may be relevant for researchers and coaches. Future research should focus on upper limbs behavior and on the analysis of the training drills used to improve starting performance.

Background: Cerebral palsy (CP) is the most common cause of motor disability in children and can cause severe gait deviations. The sagittal gait patterns classification for children with bilateral CP is an important guideline for the planning of the rehabilitation process. Ankle foot orthoses should improve the biomechanical parameters of pathological gait in the sagittal plane. Methods: A systematic search of the literature was conducted to identify randomized controlled trials (RCT) and controlled clinical trials (CCT) which measured the effect of ankle foot orthoses (AFO) on the gait of children with spastic bilateral CP, with kinetic, kinematic, and functional outcomes. Five databases (Pubmed, Scopus, ISI Web of SCIENCE, SciELO, and Cochrane Library) were searched before February 2020. The PEDro Score was used to assess the methodological quality of the selected studies and alignment with the Cochrane approach was also reviewed. Prospero registration number: CRD42018102670. Results: We included 10 studies considering a total of 285 children with spastic bilateral CP. None of the studies had a PEDro score below 4/10, including five RCTs. We identified five different types of AFO (solid; dynamic; hinged; ground reaction; posterior leaf spring) used across all studies. Only two studies referred to a classification for gait patterns. Across the different outcomes, significant differences were found in walking speed, stride length and cadence, range of motion, ground force reaction and joint moments, as well as functional scores, while wearing AFO. Conclusions: Overall, the use of AFO in children with spastic bilateral CP minimizes the impact of pathological gait, consistently improving some kinematic, kinetic, and spatial-temporal parameters, and making their gait closer to that of typically developing children. Creating a standardized protocol for future studies involving AFO would facilitate the reporting of new scientific data and help clinicians use their clinical reasoning skills to recommend the best AFO for their patients.

Cross-cultural adaptation and psychometric testing. To conduct the cross-cultural adaptation of the Quebec Back Pain Disability Scale (QBPDS) and investigate its reliability and validity in patients with chronic low back pain (CLBP). The QBPDS is one of the most commonly used scales to evaluate functional incapacity resulting from low back pain. Although measuring disability is an important outcome in physiotherapy care, there is no previous research relating to the cultural adaptation and psychometric testing of the QBPDS in the Portuguese-speaking population. The questionnaire was first translated and back-translated in accordance with the published guidelines. The Portuguese version of the QBPDS was then pilot tested in a Portuguese sample of 40 patients with CLBP. Psychometric properties were evaluated in a new sample of 132 patients with CLBP. Exploratory factor analysis was performed to confirm its unidimensionality. Reliability was evaluated through internal consistency and reproducibility, using the Cronbach α and intraclass correlation coefficient, respectively. Construct validity was assessed with correlations between the QBPDS and the Roland-Morris Disability Questionnaire and between the QBPDS and the visual analogue pain scale for convergent validity and pain localization for discriminative validity, using the Spearman correlation analysis and the Mann-Whitney test. Exploratory factor analysis revealed the existence of one major factor that explains 52.1% of the variance. One-week test-retest reliability was 0.7, and internal consistency was 0.95. The QBPDS correlated strongly with the Roland-Morris Disability Questionnaire (0.62; P < 0.001), moderately with pain (0.38; P < 0.001), and shows capability to discriminate between patients with localized and referred pain (U = 1218; P < 0.0005). The reliability and construct validity of the Portuguese version of the QBPDS are acceptable to assess functional status of Portuguese-speaking patients with CLBP. .

Gait changes due to aging can result in functional limitations and a higher risk of falls, with older adults showing alterations in joint angles and moments. Marker-based gait analysis is not widely used in clinical settings due to its complexity and discomfort, especially in older adults. Recent advances in markerless motion capture, such as Theia3D, offer a promising alternative. This study aims to assess the construct validity of a markerless motion capture system for gait analysis in healthy older adults. A cross-sectional study included 30 healthy community-dwelling older adults. Gait data was collected using marker-based and markerless motion capture systems in randomized order, with participants wearing tight-fitting minimal clothes plus 46 reflective markers attached, or their usual clothes, respectively. Joint kinematics (including range of motion) and kinetics were analyzed, and correlations between methods (Rxy) were assessed. Bland&Altman analysis was used to measure agreement. Root-mean-square differences (RMSD) were computed. Acceptable thresholds were set at ≤ 5º for kinematic and at ≤ 10 % of signal amplitude for kinetics. Strong correlations (Rxy≥0.7) were found between the systems for sagittal plane kinematics (except for the pelvis), particularly for knee and ankle joints. A low agreement was detected in sagittal plane hip and pelvis kinematics, along with RMSD exceeding 5º. Weaker correlations and poor agreement were observed for transverse and frontal plane motions. Overall strong correlations were found for kinetics, except for the joint ankle inversion-eversion moment, and poor agreement for the frontal and transverse planes. Overall markerless motion capture demonstrated good construct validity for measuring sagittal plane gait lower-limb gait kinematics (excluding pelvis) and kinetics in healthy older. However, considering the agreement between methods and the results for the other movement planes, further validation is required before markerless and marker-based systems can be used interchangeably in gait assessments.