Differences in foot contact times between obese and non-obese postmenopausal women when crossing obstacles.

OBJECTIVE: This study aimed to investigate the foot contact time differences between obese and non-obese subjects during walking when crossing obstacles. METHODS: Ninety-eight postmenopausal women were assigned to four groups, and their plantar pressure temporal data were collected using a two-step protocol during walking when crossing an obstacle set at 30% height of lower limb length of each subject. The initial, final, and duration of contact of 10 foot areas were measured. RESULTS: Leading limb: (1) the heel groups initiated foot contact using the heel, and the non-heel groups initiated contact using the metatarsals; (2) heel obese subjects showed an earlier initial contact and a longer contact duration of metatarsals 2-3; (3) non-heel obese subjects showed an earlier midfoot initial contact. Regarding the trailing limb: (4) heel obese subjects showed an earlier midfoot initial contact and a longer contact duration of metatarsal 5; (5) non-heel obese subjects showed an earlier initial contact and a longer contact duration of metatarsals 4-5. CONCLUSIONS: (1) The non-heel groups' foot rollover pattern may result from an attempt of rapidly restoring stability; (2) the heel obese subjects seem to regulate their plantar foot muscles to overcome their overweight; (3) the overweight of the non-heel obese subjects leads to a quicker backward foot roll-over from the metatarsals to the heel; (4) the overweight of the heel obese subjects can distort their footprints and/or their higher inertia may precipitate an anticipation of the midfoot contact, which can also explain the result observed for 5.

Foot Rollover Temporal Parameters During Walking Straight Ahead and Stepping Over Obstacles: Obese and Non-Obese Postmenopausal Women.

The aim of this study was to compare the temporal foot rollover data between walking straight ahead and stepping over obstacles for obese and non-obese postmenopausal women. Plantar pressure data were collected from 67 women. The initial, final, and duration of contact of 10 foot areas were measured. Both limbs of both groups showed a longer foot contact duration on the obstacle task. Significant temporal differences were found for both groups between straight ahead and crossing obstacles on the initial, final, and duration of contact for several foot areas. The propulsion phase of the trailing limb during the obstacle task was anticipated. Regarding the leading limb, the first foot contact was not made with the heel areas; however, a backward foot rollover movement from the metatarsal to the heel areas occurred, possibly to provide support to better control the trailing limb swing phase.

Females Present Reduced Minimum Toe Clearance During Walking As Compared to Males in Active Older Adults.

BACKGROUND: Physical decline due to aging has been associated with the risk of falls. Minimum toe clearance (MTC) is a gait parameter that might play a role in the mechanism of tripping and falling. However, it is unclear if there are any sex-related effects regarding MTC as people age. The present study investigated if there are sex-related differences in MTC in older active adults. METHODS: Twenty-three females and 23 males (F: 65.5 ±â€…4.8 years; M: 61.9 ±â€…5.2 years) walked on a treadmill at a preferred walking speed, while kinematic data were obtained at a sampling frequency of 100 Hz and up-sampled to 120 and 240 Hz. MTC was calculated from the kinematics data and evaluated concerning its magnitude (ie, MTC and MTC/leg length), the time between left/right MTC (ie, T-MTC), amount of variability (ie, coefficient of variation [CV] and coefficient of variation modified [CVm]), and temporal structure of variability, that is, the complexity of the time series (ie, MTC α, T-MTC α). RESULTS: No sex effects were found for MTC/leg length, for the amount of variability (ie, CV and CVm), and for the complexity of the time series (MTC α, T-MTC α). However, females exhibited significantly lower MTC and T-MTC after adjusting for walking speed, mass, and age as covariates. CONCLUSIONS: The reduced MTC in females suggests a potential sex-related disparity in the risk of tripping and falling among active older adults.

Mechanical properties of the triceps surae: differences between football and non-football players.

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 measured in vivo using 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.

Free-oscillation technique: The effect of the magnitude of the impulse applied on muscle and tendon stiffness around the ankle.

The importance of the muscle-tendon complex in sport and for activities of everyday living is well recognised. The free oscillation technique is frequently used to determine the musculo-articular "apparent" stiffness (obtained from vertical ground reaction force) and other parameters. However, an in-depth understanding of the muscle-tendon complex can be gained by separating the muscle (soleus) and the tendon (Achilles tendon) components and studying the "true" stiffness for each of these components (by considering the ankle joint moment arms), which can be valuable in improving our understanding of training, injury prevention, and recovery programs. Hence, this study aimed to investigate if muscle and tendon stiffness (i.e., "true" stiffness) are similarly affected by different impulse magnitudes when using the free-oscillation technique. Three impulse magnitudes (impulse 1, 2 and 3), corresponding to peak forces of 100, 150 and 200 N, were used to estimate the stiffness of the ankle joint in 27 males, using multiple loads (10, 15, 20, 25, 30, 35, and 40 kg). A significant decrease (p < 0.0005) was found in musculo-articular "apparent" stiffness (29224 ± 5087 N.m-1; 27839 ± 4914 N.m-1; 26835 ± 4880 N.m-1) between impulses 1, 2 and 3 respectively, when loads were collapsed across groups. However, significant differences (p < 0.001) were only found between the median (Mdn) of impulse 1 (Mdn = 564.31 (kN/m)/kN) and 2 (Mdn = 468.88 (kN/m)/kN) and between impulse 1 (Mdn = 564.31 (kN/m)/kN) and 3 (Mdn = 422.19 (kN/m)/kN), for "true" muscle stiffness, but not for "true" tendon stiffness (Mdn = 197.35 kN/m; Mdn = 210.26 kN/m; Mdn = 201.60 kN/m). The results suggest that the musculo-articular "apparent" stiffness around the ankle joint is influenced by the magnitude of the impulse applied. Interestingly, this is driven by muscle stiffness, whereas tendon stiffness appears to be unaffected.

Pro-Environmental Behaviors: Relationship With Nature Visits, Connectedness to Nature and Physical Activity.

PURPOSE: Examine the association of visits to the natural environment, connectedness to nature, physical activity, and the adoption of pro-environmental behaviors (PEBs) in individuals aged 18 years or older. DESIGN: Cross-sectional study. SETTING: City of Vila Real, located in the north of Portugal. SUBJECTS: We recruited 194 individuals (61 men and 133 women) aged 18-75 years. MESURES: A self-administered questionnaire was used to measure nature visits, connectedness to nature, PEBs, and demographic characteristics. Neighborhood green space was appreciated through a Simplified Land Occupation Map and physical activity was measured using ActiGraph accelerometers (wGT3X-BT). ANALYSIS: Correlations and nonlinear canonical correlation analysis were used to analyze the data. The coefficients of canonical and multiple correlations were calculated. RESULTS: Nature visits were associated with involvement in environmental volunteering (V = .317, P ≤ .05) among men. In these, higher levels of moderate-vigorous PA were associated with green travel behavior (η2 = .325, P ≤ .05). Connectedness with nature was related (P ≤ .05) to private sphere behaviors, such as purchase of eco-products (η2 = .191) and local/seasonal products (η2 = .186) in females and encouraging care and protection of natural environment (η2 = .336, P ≤ .01) in males. CONCLUSIONS: Nature visits, connection to nature, and physical activity levels were related to the adoption of PEBs in the private and public sphere, and these relationships differed between men and women.

Connectedness to Nature Does Not Explain the Variation in Physical Activity and Body Composition in Adults and Older People.

Connectedness to nature (CN) is a significant predictor of pro-environmental behaviours, human health and well-being. However, research on how this connection to the natural world might promote a more active lifestyle and improve body mass composition according to gender is lacking. This study investigated the influence of CN on physical activity (PA) and body composition in adults and older people. We recruited a sample of 219 individuals (77 men and 142 women), and a self-administered questionnaire was used to measure CN and obtain demographic data. Body composition was assessed by bioimpedance, and PA was assessed by accelerometry. Correlations and stepwise multiple regressions were used in data analysis. CN's association with other variables was more pronounced in women than in men, and we only identified significant associations with steps/day and body composition. However, this variable would not be included in the regression models that we developed. Adiposity levels and muscle status were significant predictors of PA in women. In both genders, age, percentage of fat mass and fat-free mass were selected as regressors in the models developed for visceral fat area and muscle condition (R2 Adjusted ≥ 0.908).

The effect of sex and localised fatigue on triceps surae musculoarticular stiffness.

PURPOSE: The main purpose of this study was to investigate the influence of fatigue on musculoarticular stiffness (MAS) of the ankle joint across sexes. METHODS: Twenty-seven males and 26 females participated in the study. After baseline assessment of MAS and related variables, localised fatigue was induced in triceps surae using the standing heel-rise test during which the subjects were instructed to lift and drop the heel at a frequency of 0.5 Hz. When subjects were unable to continue due to exhaustion the test was terminated and another MAS test was performed soon after. RESULTS: Significant higher triceps surae MAS was found in men compared to women (p < .01). MAS decreased (p < .01) between pre- and post-fatigue on average from 18.0 to 17.0 KN m-1 and from 14.5 to 13.9 KN m-1 in men and women, respectively. Percentage changes revealed, however, that in relative terms the changes in all the variables evaluated were similar (p > .01) between sexes, with MAS less than 5%. CONCLUSION: Despite the sex-related differences at baseline, fatigue seems to affect biomechanical properties of the ankle joint similarly in men and women.

Musculo-articular stiffness is affected by the magnitude of the impulse applied when assessed with the free-oscillation technique.

Musculo-articular stiffness (MAS) of the triceps surae can be assessed using the free-oscillation technique whereby an impulse is applied and the ensuing damped oscillations are recorded. The purpose of this study was to investigate if impulses of different magnitudes can affect the measurement of MAS. Twenty seven males (20.7±1.3 years) participated in this study. Three impulses of different magnitude (1.5, 2.3 and 3.1Ns) and four different loads (10, 20, 30, 40kg) were employed in the assessment of triceps surae MAS, which was quantified and compared across loads and perturbations. As the magnitude of the impulse applied increased, the MAS (p<0.0005, ES 1.20) and natural frequency of oscillation (f) decreased while the amplitude of movement (AM), angular velocity (ω) and damping coefficient (C) increased significantly. As the load level increased, the MAS (p<0.0005, ES 2.25) and the baseline ground reaction force (BGRF) increased whereas f, AM and ω decreased significantly. Even though the effect of the load is stronger, it appears that the level of MAS recorded (ranging from 24.0 to 21.3KN/m for the 10kg load and from 32.9 to 31.0KN/m for the 40kg load, for impulse 1 and 3 respectively), including several underlying factors, are affected by the magnitude of the impulse, therefore its accurate determination is pivotal. Caution should be exercised when comparing results from previous studies where the magnitude of the impulse has only been estimated but not controlled for.

Foot Rollover Temporal Parameters During Straight-Ahead and Side-Cut Walking in Obese and Nonobese Postmenopausal Women.

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.

Behavior of temporal parameters of the ground reactive forces for the walking of postmenopausal women.

The study aimed to examine the influence of body composition and menopause characteristics on certain temporal parameters of the behavior of vertical and anteroposterior components of ground reactive forces, as well as the vertical and anteroposterior rates on the walking of postmenopausal women. The sample consisted of 67 postmenopausal women, average age 59 years. Body composition was assessed by octapolar bioimpedance and ground reactive force by the Kistler force platform. Vertical loading rate correlated positively with age (r = 0.02) and negatively with weight (r = -0.33). The relationship between the rates of vertical loading and unloading associated positively with menopause time (r = 0.27) but negatively with weight (r = -0.27). Vertical unloading rate showed a negative association with abdominal visceral adiposity (r = -0.27). The relationship between the times of the intermediate and final phases of the support correlated significantly with abdominal visceral adiposity (r = 0.25) and fat mass (r = 0.24). The study suggests that fat mass and abdominal visceral adiposity affect the support time, and increased abdominal visceral adiposity implies a slower pre-suspension phase during the walking of postmenopausal women. Hormone replacement therapy was shown to be an enhancer of steeper vertical loading and anteroposterior unloading and longer time in the double support phase, indicating a greater stability of postmenopausal women when walking.

Biomechanical properties of the triceps surae muscle-tendon unit in young and postmenopausal women.

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.

The relationship of body mass index, age and triceps-surae musculotendinous stiffness with the foot arch structure of postmenopausal women.

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.

Triceps-surae musculotendinous stiffness: relative differences between obese and non-obese postmenopausal women.

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.