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According to the World Health Organization, one-third of elderly people aged 65 or over fall annually, and this number increases after 70. Several gait biomechanical parameters were associated with a history of falls. This study aimed to conduct a systematic review to identify and describe the gait biomechanical parameters related to falls in the elderly. MEDLINE Complete, Cochrane, Web of Science, and CINAHL Complete were searched for articles on 22 November 2023, using the following search sentence: (gait) AND (fall*) AND ((elder*) OR (old*) OR (senior*)) AND ((kinematic*) OR (kinetic*) OR (biomechanic*) OR (electromyogram*) OR (emg) OR (motion analysis*) OR (plantar pressure)). This search identified 13,988 studies. From these, 96 were selected. Gait speed, stride/step length, and double support phase are gait biomechanical parameters that differentiate fallers from non-fallers. Fallers also tended to exhibit higher variability in gait biomechanical parameters, namely the minimum foot/toe clearance variability. Although the studies were scarce, differences between fallers and non-fallers were found regarding lower limb muscular activity and joint biomechanics. Due to the scarce literature and contradictory results among studies, it is complex to draw clear conclusions for parameters related to postural stability. Minimum foot/toe clearance, step width, and knee kinematics did not differentiate fallers from non-fallers. [ABSTRACT FROM AUTHOR]

Falls are a major concern in the elderly and walking is an important daily activity in which falls occur, with tripping and slipping being the most frequent causes. Gait biomechanical parameters have been related to the occurrence of falls in the elderly. Moreover, there is evidence that falls can be prevented through exercise programs, which have been shown to be also effective in improving gait biomechanical parameters. However, a question remains: "What types of exercises must be included in exercise programs to prevent falls?". The purpose of this manuscript was to present guidelines for a fall prevention exercise program for the elderly, which was created with the aim of improving the gait biomechanical parameters related to falls. The critical review performed during the preparation of this manuscript collected important evidence and knowledge in order to create a structural basis for the development of a fall prevention exercise program. This type of program should last 6 or more weeks and be prescribed based on four movement pillars (locomotion, level changes, pulling and pushing, and rotations); however, the locomotion pillar must be the focus of the program. Proprioceptive and functional strength exercises should be included in this program. Based on the theoretical rationale, a proposal for a fall prevention exercise program is presented. [ABSTRACT FROM AUTHOR]

The aim of this study was to perform a biomechanical characterization of the gait cycle in individuals who are blind. Five individuals with ages between 16 and 19 years participated in this study. The task consisted of walks of 12m measured in two conditions: (1) with cane and (2) wihtout cane; a total of 20 walks in each condition were performed. During walks, participants were monitored with a Vicon 3D-motion capture system. Spatialtemporal, kinematic, kinetic, and dynamic parameters were recorded and compared between the two conditions. We observed an interaction between the condition and ankle angular measures (p = .003); the interaction was due to differences induced by condition in instants ‘opposite toe off’ (p = .045) and ‘opposite initial contact’ (p = .019). We also obtained a significant difference in the negative ankle-joint-power measures between conditions (p = .044). This study showed that the use of cane changes the gait pattern in individuals who are blind. The subtle changes in ankle behaviour when walking with a cane, compared with no cane, suggest better application of the force during the initial stages of support leading to a more comfortable gait. This type of assessment of gait may be important to improve mobility training and rehabilitation strategies. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the temporal foot rollover data between straight-ahead and side-cut walking and to establish a reference dataset for obese and nonobese postmenopausal women. Pressure data were collected using the two-step protocol. The initial, final, and duration of contact of 10 foot areas were measured, as 5 instants and 4 phases. Significant temporal foot rollover differences were found during walking with and without directional changes; however, most of these differences were common for obese and nonobese subjects.The trailing limb during the side-cut task anticipated the initial and final contact of the lateral forefoot and increased midfoot and toes duration, suggesting a greater role of these areas in the initial break and in foot stability. The leading limb throughout the side-cut task exhibited longer duration of the heel, midfoot, and stance phase probably due to an increase in the stride length of the trailing limb and leaning of the trunk toward the inner side of the turn. Additionally, obese women revealed a later final contact and longer contact duration of some metatarsal areas suggesting that the greater inertia of these subjects demands more time to stabilize and prepare the foot for the next step. Please provide 3 to 5 keywords for the article. [ABSTRACT FROM AUTHOR]

Muscle stretch-shortening cycle (SSC) is a central mechanism with lower limb muscle contraction immediately preceded by muscle stretch for efficient submaximal activities such as gait and powerful maximal activities such as running and jumping [1,2]. Although muscle SSC can be observed at gait and running its higher expression and accessibility is performed on standard maximum vertical jump (MVJ) with an open issue on neuromuscular control assessment of lower limb muscle SSC [3]. For this purpose, we present and applied noninvasive subject specific analysis of lower limb muscle coactivation for selected muscles with higher contribution during MVJ impulse based on corresponding conditioned surface electromyographic signals (sEMG). Selected muscles correspond to lower limb muscles vastus medialis (VM), rectus femoris (RF), vastus lateralis (VL), lateral gastrocnemius (LG) and medial gastrocnemius (MG). Twenty-seven trials were assessed corresponding for each subject to the highest MVJ based on larger flight time with long SSC at countermovement jump (CMJ), short SSC at drop jump (DJ) and squat jump (SJ) with no SSC. Trial sample is composed by a group of six young adult volunteers' students on sports and physical education degree with the ages (21.5 ± 1.4) years, (76.7 ± 9.3) kg mass and (1.79 ± 0.06) m height. Surface skin was prepared and Aqua-Wet gel Skintact F55 electrodes were applied at bipolar configuration as indicated by SENIAN. VM, RF, VL, LG and MG sEMG linear envelopes were paired plotted with the area under the curves computed as well as the coactivation pairs defined as the common area under the curves normalized to the sum of the corresponding pair individual areas under the curves. Coactivations were compared at CMJ, DJ and SJ as well as among CMJ, DJ and SJ, Fig. 1. Strongest coactivations with decreasing intensity were detected between VM-RF and LG-MG muscles at CMJ and SJ, whereas at DJ the strongest coactivation was detected between LG-MG and VL-MG as presented at Fig. 1. Also, while the coactivations between quadriceps selected muscles VM-RF, VM-VL and RF-VL presented higher values at CMJ and SJ than DJ, the coactivations between the quadriceps selected muscles and the gastrocnemius presented higher values at CMJ and DJ than SJ. [Display omitted] Fig. 1. sEMG linear envelopes and coactivations (COACT). Despite the strongest coactivation was detected at intramuscular group level, these muscular groups were distinct depending on MVJ type, with the highest coactivation of the selected quadriceps muscles detected at CMJ and SJ whereas the highest coactivations on DJ was detected at the gastrocnemius. Additionally, similar pattern arises on muscle coactivations at CMJ, DJ and SJ with higher values at CMJ than DJ and SJ for VM-RF, VM-VL, VM-LG, VM-MG and RF-VL whereas CMJ and DJ presented higher values than SJ at RF-LG, RF-MG, VL-LG, VL-MG, and LG-MG. [ABSTRACT FROM AUTHOR]

Standard maximum vertical jump (MVJ) has been applied to assess lower limb long countermovement (CM) on countermovement jump (CMJ) and short CM on drop jump (DJ) for comparison to squat jump (SJ) without CM [1,2]. Nevertheless, the ability for lower limb joint accelerations depending on lower limb joint angles at long, short and no CM remains an open issue [3,4], in particular linearity assessment of these relations at long, short and no CM in association with MVJ whole-body impulsion. For this reason, we applied piecewise linear detection of segmented subphases on lower limb joint angles (θ)-angular acceleration (α) diagrams for the hip (H), knee (K) and ankle (A) during impulse phases on CMJ, DJ and SJ. Selected sample corresponds to best MVJ trials based on higher flight-time of 3 CMJ, DJ and SJ repetitions for six healthy untrained subjects with ages (21.5±1.4) years, (76.7±9.3)kg mass and (1.79±0.06)m height. Adhesive reflective markers were applied at lower limb and torso, with sagittal hip, knee, and ankle θ , α obtained by inverse kinematics. H,K,A (θ , α) diagrams were plotted and impulsion subphases segmented at selected instants of ∂ a /∂ q phase reversal with linear fit by the least-squares method, Fig. 1. [Display omitted] Fig. 1. Hip, knee, ankle joint (θ , α) diagrams at CMJ, DJ, SJ with segmented subphases time span(Δt), |∂α/∂θ| slope magnitudes and R² linear fit regression. SJ presented larger number of (θ , α) subphases than DJ, both larger than CMJ with higher |∂ α /∂ θ | variation at DJ and SJ than CMJ, pointing to higher complexity of neuromuscular control and contributing to explain reduced SJ, DJ performance without CM (0.33±0.05)m and with short CM (0.27±0.03)m in relation to CMJ with long CM (0.36±0.04)m for untrained selected subjects, Fig. 1. Thus, despite the larger total time span Δt at CMJ (0.76±0.10)s in relation to SJ (0.36±0.08)s and DJ (0.23±0.05)s, CMJ presented lower number of subphases with longer time span, whereas DJ and SJ present higher number of segmented subphases with shorter partial and total time span. CMJ presented lower |∂ α /∂ θ | than DJ and SJ, with hip, and the knee higher magnitudes on CMJ for the latest subphase C, whereas the ankle presented higher magnitudes at the latest subphases B and C. DJ is characterized by higher |∂ α /∂ θ | particularly for the hip in relation to the knee and the ankle. Finally, SJ presented intermediate |∂ α /∂ θ | with the highest values of the subphase A for the hip, the knee, and the ankle in relation to the remaining subphases. Regarding R ² linear fit regression, CMJ presented at the latest subphase C higher values for H,K,A, whereas DJ presented general stronger R ² and SJ moderate R ² at initial subphases A,B and stronger values at later phases. [ABSTRACT FROM AUTHOR]

The Hurdle Step test (HS) is one of the seven tests included in the Functional Movement Screen (FMS), a widely used clinical tool that assesses joint mobility and postural stability deficits.(1) However, there is the need to study FMS validity.(2) Convergent validity is defined as how closely the scale is associated with other measures of the same construct,(3) demonstrated by a high correlation between them.(4) HS aims to assess postural stability during an unipedal stance.(1) Postural stability refers to the ability of a self-controlled body to maintain adequate movement sustainability.(5) Kinematic parameters of the centre of pressure (CoP) and centre of gravity projection (CoGp) have been used to study postural stability.(6–8) To the best of our knowledge, no research has studied the relation between HS score and biomechanical parameters related to postural stability. Does HS present convergent validity regarding postural stability and the ability to discriminate between subjects with different levels of stability? Twenty-six healthy subjects were included (22.2±1.7 years; 3 women). Subjects performed five repetitions of the HS for each lower limb according to the FMS guidelines.(1) Subjects scored as "0" or injured were excluded. Subjects' performances in frontal and sagittal plane were recorded using two cameras and afterwards scored by two FMS certificated evaluators. The kinematic parameters of the CoP and CoGp presented in Table 1 were collected using a 3D motion analysis system (Vicon®;200 Hz) and a force plate (AMTI;1000 Hz). These parameters were studied during the stance phase of the forward (phase 1) and backward step (phase 2). Spearman's coefficient studied the correlation between HS score and biomechanical parameters. Mann-Whitney test assessed the ability of HS to discriminate between subjects with different scores ("1","2","3"). [Display omitted] No subject was scored as "1". Fig. 1 shows the CoGp and CoP displacements in the horizontal plane (examples of a subject scored as "2" and a subject scored as "3"). HS scores presented low to moderate correlations with: CoP-CoGp average anteroposterior distance (R=0.552;p<0.05), CoP average anteroposterior velocity (R=-0.282;p<0.05); CoGp average mediolateral (R=-0.280;p<0.05) and anteroposterior velocity (R=-0.397;p<0.05), CoGp anteroposterior velocity peak (R=-0.439;p<0.05), CoP sum of mediolateral displacements (R=0.319;p<0.05), CoP range of anteroposterior displacement (R=-0.293;p<0.05), CoP-CoGp range of mediolateral (R=-0.276;p<0.05) and anteroposterior distance (R=-0.434;p<0.05), and CoP-CoGp range of distance (R=-0.312;p<0.05) – phase 1; CoGp average anteroposterior velocity (R=-0.279;p<0.05) and CoP-CoGp average anteroposterior distance (R=0.444;p<0.05) – phase 2; the other biomechanical parameters presented no correlations. Differences between groups of subjects scored as "2" or "3" are presented in Table 1. HS presented low convergent validity regarding postural stability. Although HS has shown some ability to discriminate subjects with different levels of postural stability, the fact that there were no subjects scored as "1" may indicate some limitations of the test to discriminate subjects at more levels. [ABSTRACT FROM AUTHOR]