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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]

We investigated the mechanical properties of the triceps surae between professional, junior, and non-football players. Fifty-nine men participated in this study. The mechanical properties of the right legs’ triceps surae were measuredin vivousing a free oscillation technique; no significant differences existed between the groups. The mean results for musculo-articular stiffness, damping coefficient, and damping ratio were as follows: professional football players (21523 N· m−1, 330.8 N · s · m−1, and 0.201); junior football players (21063 N · m−1, 274.4 N · s · m−1, and 0.173); and non-players (19457 N · m−1, 281.5 N · s · m−1, and 0.184). When analysed according to position, the results were as follows: defender (21447 N · m−1, 308.6 N · s · m−1, and 0.189); midfielder (20762 N · m−1, 250.7 N · s · m−1, and 0.157); winger (21322 N · m−1, 335.1 N · s · m−1, and 0.212); forward (22085 N · m−1, 416.2 N · s · m−1, and 0.254); and non-players (19457 N · m−1, 281.5 N · s · m−1, and 0.184). Thus, football training, football games, and the position played had no effect on triceps surae mechanical properties. These results may be attributed to opposing adaptations between different types of training that are usually implemented in football. Alternatively, the minimum strain amplitude and/or frequency threshold of the triceps surae required to trigger adaptations of mechanical properties might not be achieved by football players with football training and matches. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To characterize and compare dynamic joint stiffness (DJS) of the ankle in the sagittal plane during natural cadence walking in both genders. Design: Observation, cross-sectional and matched pairs. Participants: Twenty-one males (mean age=27±4.2 years) and 18 females (mean age=22.9±4.1 years). Setting: Laboratory at the University de Trás-os-Montes and Alto Douro. The DJS of the ankle was assessed while participants performed barefoot walking at a natural cadence, was measured using a force platform (1000Hz), and synchronized with a high-speed camera (200Hz). Main outcome measures: DJS of the ankle in males and females was calculated in two sub-phases (the second and the fourth sub-phases) of the stance phase. The Wilcoxon non-parametric matched-pairs test and the Mann–Whitney U non-parametric test were used to analyse difference of DJS of the ankle within and between the groups with p⩽0.05 regarded as significant. Results: Male and female participants demonstrated significantly (p<0.005) less DJS during the second sub-phase. DJS was not significantly (p>0.063) different between females (0.0511Nm/kg/°) and males (0.0596Nm/kg/°) during the second sub-phase. DJS was significantly (p<0.001) higher in males (0.0844Nm/kg/°) than females (0.0691Nm/kg/°) during the fourth sub-phase. Conclusions: Gender-specific DJS characteristics demonstrated by females in this study may be used in preventative training programs designed to promote a greater ability to use contractile components to produce mechanical energy through the ankle. [Copyright &y& Elsevier]

This work presents a general three-dimensional multibody procedure for studying the human body motion with emphasis on the locomotion apparatus. The methodology includes a three-dimensional biomechanical model, data acquisition techniques and an inverse dynamics approach. The biomechanical model is based on a multibody formulation using natural coordinates and consists of 16 anatomical segments modeled by 33 rigid bodies for a total of 44 degrees-of-freedom. The action of the muscles is introduced in the equations of motion of the multibody model by means of driver actuators defined as kinematic constraints. By associating a Lagrange multiplier to each muscle actuator the muscle forces became coupled with the biomechanical model through the Jacobian matrix of the underlying multibody system. A Hill type muscle model is used to calculate individual muscle forces. The model for the muscle apparatus comprises 43 muscle groups for each leg, which use the full three-dimensional lines of action for these muscles in their geometric description. The problem of the redundancy of the forces on the musculoskeletal structure is solved by using inverse dynamics and static optimization methods. In the process of describing the methodology the benefits of modeling in natural coordinates are highlighted. The methodology developed is demonstrated through its application to a case of ballistic motion, represented by the take-off to an aerial trajectory in order to estimate the joint torques and the muscle force distribution in the supporting leg. The time characteristics of the resultant net torques at the basic joints of the supporting leg and the time-varying muscle force patterns are presented and discussed. The results obtained are explained in terms of their relevance to the activity under study. [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]

Abstract: Background: Insufficient and excessive stiffness may increase the risk of soft tissue and bone injuries, respectively, while the resonance frequency seems to be related with energy expenditure and stiffness. With aging and menopause muscle weakness, physical fragility and mobility limitations are also expected. Therefore this study addresses the differences of biomechanical properties of the triceps surae muscle–tendon unit between young and postmenopausal women. Methods: 39 young and 37 postmenopausal women participated. The biomechanical properties of the triceps surae muscle–tendon unit were assessed in vivo using a free oscillation technique involving 30% of the maximal voluntary isometric contraction load. Findings: The postmenopausal women in this study show significant higher values in the damped natural frequency of oscillation (young 3.84Hz vs. postmenopausal 4.68Hz, P <0.001), muscle–tendon unit stiffness (young 16,446N/m vs. postmenopausal 23,229N/m, P <0.001), and muscle–tendon unit stiffness normalized by mass (young 286.3N/m vs. postmenopausal 325.1N/m, P <0.05). The postmenopausal study group shows significant lower values in the damping ratio (young 0.190 vs. postmenopausal 0.150, P <0.01) than young women. Interpretation: The postmenopausal subjects may not be able to take advantage of resonance as the young subjects, or, the relationship between these frequencies is adjusted according to the musculoskeletal characteristics of each group. The decrease in damping properties and the increase in muscle–tendon unit stiffness suggest that postmenopausal women might be at a greater risk of injury. [Copyright &y& Elsevier]

Background: Low- or high-arched feet and insufficient or excessive muscle–tendon stiffness have been identified as risk factors for lower extremity injuries. Additionally, increased body mass index and age may be responsible for structural changes of the foot, which might adversely affect the functional capacity of the longitudinal arch. Therefore, the aim of this study was to investigate the relationship of body mass, age and triceps-surae musculotendinous stiffness with the foot arch structure of postmenopausal women. Methods: 81 post menopausal women (58.0 (SD 6.0) years) participated. An in vivo free oscillation technique was used to assess musculotendinous stiffness of the ankle. The two-step protocol was used to acquire gait plantar pressure data. Dynamic arch index was calculated as the ratio of the midfoot area to the area of the entire foot excluding the toes. Three groups were formed (cavus, normal and planus). Findings: Significant differences (P <0.05) between the groups cavus and planus were found for age using the ANOVA test. Using Kruskal–Wallis tests significant differences were found for body mass index between the cavus–normal groups and cavus–planus (P <0.001) but no significant differences were found for triceps-surae musculotendinous stiffness between foot-type groups. Interpretation: Since obese subjects present greater downward vertical forces, they might be more prone to overload foot structures leading to the collapse of the medial longitudinal arch affecting adversely the functional capacity of the foot. Deterioration of the musculoskeletal system, due to age, may also affect foot arch structure. No relationship between musculotendinous stiffness and foot arch structure appears to exist. [Copyright &y& Elsevier]

Abstract: Background: There is a lack of research into the relationship between obesity and muscle–tendon unit stiffness in postmenopausal women. Muscle–tendon unit stiffness appears to affect human motion performance and excessive and insufficient stiffness can increase the risk of bone and soft tissue injuries, respectively. The aim of this study was to investigate the relationship between muscle–tendon unit stiffness and obesity in postmenopausal women. Methods: 105 postmenopausal women (58 [SD 5.5] years) participated. Four groups (normal weight, pre-obese, obesity class I and obesity class II) were defined according World Health Organization classification of body mass index. The ankle muscle–tendon unit stiffness was assessed in vivo with a free oscillation technique using a load of 30% of maximal voluntary isometric contraction. Findings: ANOVA shows significant difference in muscle–tendon unit stiffness among the groups defined (P <0.001). Post hoc analysis reveals significant differences between the following groups: normal weight–pre-obese; normal weight–obesity class I and normal weight–obesity class II. The normal weight group had stiffness of 15789 (SD 2969) N/m, pre-obese of 19971 (SD 3678) N/m, obesity class I of 21435 (SD 4295) N/m, and obesity class II of 23497 (SD 1776) N/m. Interpretation: Obese subjects may have increased muscle–tendon unit stiffness because of fat infiltration in leg skeletal muscles, range of motion restrictions and stability/posture reasons and might be more predisposed to develop musculoskeletal injuries. Normal weight group had identical stiffness values to those reported in studies where subjects were not yet menopausal, suggesting that stiffness might not be influenced by menopause. [Copyright &y& Elsevier]