Propulsion strategy in the gait of primary school children; the effect of age and speed

The strategy used to generate power for forward propulsion in walking and running has recently been highlighted as a marker of gait maturation and elastic energy recycling. This study investigated ankle and hip power generation as a propulsion strategy (PS) during the late stance/early swing phases of walking and running in typically developing (TD) children (15: six to nine years; 17: nine to 13 years) using three-dimensional gait analysis. Peak ankle power generation at push-off (peakA2), peak hip power generation in early swing (peakH3) and propulsion strategy (PS) [peakA2/(peakA2 + peakH3)] were calculated to provide the relative contribution of ankle power to total propulsion. Mean PS values decreased as speed increased for comfortable walking (p < 0.001), fast walking (p < 0.001) and fast running (p < 0.001), and less consistently during jogging (p = 0.054). PS varied with age (p < 0.001) only during fast walking. At any speed of fast walking, older children generated more peakA2 (p = 0.001) and less peakH3 (p = 0.001) than younger children. While the kinetics of running propulsion appear to be developed by age six years, the skills of fast walking appeared to require additional neuromuscular maturity. These findings support the concept that running is a skill that matures early for TD children.     

Experiential avoidance in body dysmorphic disorder

Experiential avoidance (i.e., the attempt to avoid certain internal experiences including bodily sensations, thoughts, emotions, memories, and urges) has been studied in various psychological disorders. However, research examining experiential avoidance in individuals with body dysmorphic disorder (BDD) is limited and inconsistent. The present study compared experiential avoidance in individuals with primary BDD (n = 23) to healthy controls (n = 22). Standardized measures were used to assess baseline clinical characteristics as well as experiential avoidance. Compared to healthy controls, individuals with BDD presented with significantly greater experiential avoidance (p < .001, d = −2.51). In BDD, experiential avoidance was positively correlated with depressive symptoms (p < .01) and avoidant coping strategies (p < .01). Clinician sensitivity to experiential avoidance may serve to improve the course of treatment for BDD.     

The relationship between allometry and preferred transition speed in human locomotion

The purpose of this study was to explore the relationships between preferred transition speed (PTS) and anthropometric characteristics, body composition and different human body proportions in males. In a sample of 59 male students, we collected anthropometric and body composition data and determined individual PTS using increment protocol. The relationships between PTS and other variables were determined using Pearson correlation, stepwise linear and hierarchical regression. Body ratios were formed as quotient of two variables whereby at least one significantly correlated to PTS. Circular and transversal (except bitrochanteric diameter) body dimensions did not correlate with PTS. Moderate correlations were found between longitudinal leg dimensions (foot, leg and thigh length) and PTS, while the highest correlation was found for lower leg length (r = .488, p < .01). Two parameters related to body composition showed weak correlation with PTS: body fat mass (r = −.250, p < .05) and amount of lean leg mass scaled to body weight (r = .309, p < .05). Segmental body proportions correlated more significantly with PTS, where thigh/lower leg length ratio showed the highest correlation (r = .521, p < .01). Prediction model with individual variables (lower leg and foot length) have explained just 31% of PTS variability, while model with body proportions showed almost 20% better prediction (R² = .504). These results suggests that longitudinal leg dimensions have moderate influence on PTS and that segmental body proportions significantly more explain PTS than single anthropometric variables.     

Predictors of aerobic physical activity and resistance training among Canadian adults with type 2 diabetes: An application of the Protection Motivation Theory

BackgroundIt is well established that both aerobic physical activity (PA) and resistance training are essential in the treatment and management of type 2 diabetes (T2D), but few studies have examined the determinants of both modes of PA in the same sample.PurposeThe main objective was to investigate the utility of the Protection Motivation Theory (PMT) in predicting aerobic PA and resistance training in a population sample of T2D adults.MethodsA total of 244 individuals completed self-report PMT constructs of vulnerability, severity, fear, response efficacy, self-efficacy and intention, and a 3-month follow-up that assessed aerobic PA and resistance training.ResultsPMT explained 19% (p < .001) and 20% (p < .001) of the variance respectively for aerobic PA and resistance training behaviour. Significant associations were found between self-efficacy (β = 0.45, p < .001) and gender (β = 0.15, p < .05) for aerobic PA, and self-efficacy (β = 0.48, p < .001) and age (β = 0.17, p < .05) for resistance training. PMT accounted for 43% (p < .001) and 56% (p < .001) of the variance respectively for aerobic PA and resistance training intentions. For aerobic PA, response efficacy (β = 0.14, p < .05) and self-efficacy (β = 0.59, p < .001) were significantly associated with intention, while response efficacy (β = 0.23, p < .001), self-efficacy (β = 0.64, p < .001) and age (β = 0.10, p < .05) were significantly related with resistance training intention.ConclusionsNone of the unique constructs of the PMT (i.e., perceived vulnerability, severity and fear) were significant with either aerobic and resistance training intention. These results may guide the development of effective PA interventions in people with T2D.     

Effect of an intensified training period on well-being indices,recovery and psychological aspects in professional soccer players

IntroductionIntensified training periods (IT) are associated with fatigue increase and psychological variations.ObjectiveThis investigation aimed to examine the perceived well-being, recovery quality and psychological responses during an IT.MethodsFifteen professional soccer players (mean ± SD: age: 24 ± 1 years, body mass: 71.3 ± 15.1 kg, height: 178.0 ± 6.1 cm) completed a 6-week training program consisting of 2 weeks of basic training (BT) and 4 weeks of IT. They were tested before (T1) and after (T2) the IT. Training load (TL) perception, strain and monotony were measured by the session-RPE method. Well-being indices (sleep quality, fatigue level, stress and delayed-onset muscular soreness [DOMS]) and total quality recovery (TQR) were recorded before each training session. The profile of mood states (POMS) and the Ottowa mental skills assessment tool (OMSAT)-3 were conducted before and after IT.ResultsNo significant difference was found after IT in OMSAT-3 scores (p > 0.05). TL, monotony and strain increased during IT (p < 0.001). Moreover, well-being indices (stress, sleep quality, fatigue level and DOMS) increased (p < 0.001) and TQR decreased (p < 0.001) during IT. The IT increased total mood disturbance (TMD, p < 0.001), tension (p < 0.05) and fatigue (p < 0.01) and decreased vigor (p < 0.001). Significant relationships were found between TL and Hooper Index (HI), TQR and TMD (r = 0.58, 0.65, −0.57, respectively; all p < 0.05).ConclusionThe findings of this investigation suggested that mental ability was not sensitive to fatigue caused by training load intensification. However, perceived well-being, recovery state and mood were found to be sensitive measures and may provide coaches with information about wellness and psychological state of soccer players during IT.     

The role of motion platform on postural instability and head vibration exposure at driving simulators

This paper explains the effect of a motion platform for driving simulators on postural instability and head vibration exposure. The sensed head level-vehicle (visual cues) level longitudinal and lateral accelerations (a_x,sensed = a_{x_head} and a_y,sensed = a_{y_head}, a_yv = a_{y_veh} and a_yv = a_{y_veh}) were saved by using a motion tracking sensor and a simulation software respectively. Then, associated vibration dose values (VDVs) were computed at head level during the driving sessions. Furthermore, the postural instabilities of the participants were measured as longitudinal and lateral subject body centre of pressure (X_CP and Y_CP, respectively) displacements just after each driving session via a balance platform. The results revealed that the optic-head inertial level longitudinal accelerations indicated a negative non-significant correlation (r = −.203, p = .154 > .05) for the static case, whereas the optic-head inertial longitudinal accelerations depicted a so small negative non-significant correlation (r = −.066, p = .643 > .05) that can be negligible for the dynamic condition. The X_CP for the dynamic case indicated a significant higher value than the static situation (t(47), p < .0001). The VDV_x for the dynamic case yielded a significant higher value than the static situation (U(47), p < .0001). The optic-head inertial lateral accelerations resulted a negative significant correlation (r = −.376, p = .007 < .05) for the static platform, whereas the optic-head inertial lateral accelerations showed a positive significant correlation (r = .418, p = .002 < .05) at dynamic platform condition. The VDV_y for the static case indicated a significant higher value rather than the dynamic situation (U(47), p < .0001). The Y_CP for the static case yielded significantly higher than the dynamic situation (t(47), p = .001 < 0.05).     

Similar changes in muscle fiber phenotype with differentiated consequences for rate of force development: Endurance versus resistance training

Resistance training has been shown to positively affect the rate of force development (RFD) whereas there is currently no data on the effect of endurance training on RFD. Subjects completed ten weeks of either resistance training (RT, n = 7) or endurance cycling (END, n = 7). Pre and post measurements included biopsies obtained from m. vastus lateralis to quantify fiber phenotype and fiber area and isokinetic dynamometer tests to quantify maximal torque (Nm) and RFD (Nm/s) at 0–30, 0–50, 0–100 and 0–200 ms during maximal isometric contraction for both knee extensors and flexors. Both groups increased the area percentage of type IIa fibers (p < .01) and decreased the area percentage of type IIx fibers (p = .05), whereas only RT increased fiber size (p < .05). RT significantly increased eccentric, concentric and isometric strength for both knee extensors and flexors, whereas END did not. RT increased 200 ms RFD (p < .01) in knee flexor RFD and a tendency towards an increase at 100 ms (p < .1), whereas tendencies towards decreases were observed for the END group at 30, 50 and 100 ms (p < .1), resulting in RT having a higher RFD than END at post (p < .01). In conclusion, resistance training may be very important for maintaining RFD, whereas endurance training may negatively impact RFD.     

Psychosocial determinants of road traffic offences in a sample of Spanish male prison inmates

ObjectiveThere is very little information available about the characteristics of drivers convicted for traffic offences. The objective of this study was to perform a comparative analysis of the psychosocial characteristics of Spanish prison inmates convicted of road traffic offences (CRTOs), drivers serving a prison sentence for other types of offence (DCOOs), and drivers with no criminal record (DNCRs), in order to identify the psychosocial predictors associated with RTOs.MethodsThe study sample comprised 434 male participants divided into three groups: CRTO (n = 240); DCOO (n = 85); and DNCR (n = 105). Instruments included an interview on sociodemographic data, driving behaviour, and past offences, as well as a set of tests to evaluate personality traits (ZKPQ-50CC), driving-related aspects (MDSI-S and DAS), and alcohol dependence (AUDIT).ResultsA logistic regression analysis showed the following to be reliable predictors of RTOs: low education level (p < .05); having been involved in several road traffic accidents (p < .001); having received several fines (p < .001); a high score on the MDSI-S Risky subscale (p < .05); a low score on the MDSI-S Careful subscale (p < .05); AUDIT scores > 8 (p < .05), and repeatedly driving whilst under the influence of alcohol (p < .05).ConclusionsThe results obtained have significant practical implications for designing and implementing traffic offenders programmes.     

Longitudinal examination of objectively-measured physical activity and sedentary time among children with and without significant movement impairments

BackgroundChildren with Developmental Coordination Disorder (DCD) tend to be less active than typically-developing (TD) children. Current evidence, however, is based on cross-sectional and self-reported activity, and little is known about sedentary time among children with significant movement impairments such as DCD. The current study examines the longitudinal patterns of objectively measured physical activity and sedentary time in children with and without possible DCD (pDCD).MethodsData is from a longitudinal nested case-control study, with 103 participants (n = 60 males ages = 12 and 13 at baseline). Participants averaging ⩽16th percentile on the Movement Assessment Battery for Children were considered having significant movement impairments and pDCD (n = 49). All participants wore accelerometers for seven days.ResultsThere were significant main effects for time (Estimate = −23.98, p < .01) and gender (Estimate = 59.86, p < .05) on total physical activity, and time spent being sedentary (Estimate = 15.58, p < .05). Significant main effects for pDCD (Estimate = −5.38, p < .05) and gender (Estimate = 26.89, p < .01), and time by gender interaction (Estimate = −7.50, p < .05) were found for moderate-to-vigorous physical activity (MVPA). Sedentary time did not differ between children with and without DCD.ConclusionsResults suggest children with pDCD engaged in less MVPA compared to TD children. Consistent patterns of MVPA over time, however, suggest that the divergence in MVPA occurs earlier in childhood. Further longitudinal research following a younger cohort is necessary to identify the specific point that differences in MVPA emerge.     

Relative effects of reduced weight and increased physical activity on hemoglobin A1c: Suggestions for behavioral treatments

Behavioral treatments for diabetes have often been unsuccessful and may benefit from a better understanding of the relative effects of two common treatment foci – decreased weight and increased volume of physical activity – on blood glucose. Overweight and obese adults (N = 59; M_age = 60 years) with hemoglobin A1c (HbA1c) values consistent with diabetes participated in a 6-month community-based behavioral treatment based on tenets of self-efficacy theory and social cognitive theory. The treatment was associated with significantly increased physical activity, reduced body mass index (BMI), and reduced HbA1c levels (ps < .001). Changes in BMI and physical activity accounted for a significant portion of the variance in change in HbA1c, R² = .13, p = .023. Change in volume of physical activity, β = ?.36, p = .007, but not change in BMI, β = ?.03, p = .792, significantly contributed to the variance in HbA1c change that was accounted for. There was no effect based on the sex of participants. Discussion focused on how findings might impact the efficacy, efficiency, and application of behavioral treatments for diabetes management.     

Adaptation of lower limb movement patterns when maintaining performance in the presence of muscle fatigue

Adaptations in lower limb movement patterns were examined when performance was maintained during a fatiguing repetitive loading task. Forty recreationally active male and female participants performed single-leg hopping to volitional exhaustion at 2.2 Hz to a submaximal height. Spatio-temporal characteristics, mechanical characteristics and variability of the knee-ankle and hip-knee joint couplings were determined at 20% increments during the duration of the hopping task. Variability of the knee-ankle and hip-knee couplings in the flexion/extension axis significantly increased during the loading and propulsion phases during the hopping task (p < 0.05). Performance (vertical stiffness, hopping frequency and height) did not change significantly during the task (p > 0.05), however foot contact time increased progressively during this task (p < 0.05) and maximum hop height significantly decreased after the task (p < 0.05). The observed increase in variability between adjoining lower limb segments demonstrated the ability of the neuromotor system to adapt and maintain performance even with the onset of fatigue. This finding highlights that during the performance of a rapid and repetitive loading activity, performance can be preserved when there is variability in the neuromotor system.     

Longitudinal patterns of change in eye–hand coordination in children aged 8–16 years

Enhanced eye–hand coordination (EHC) is associated with greater participation in physical activity. No longitudinal studies have examined the change in throw–catch EHC from childhood to mid-adolescence. We investigated the development of EHC with an object control test from childhood to mid-adolescence in boys and girls. Evaluated at age 8, 10, 12 and 16 years, EHC was measured as the aggregate success rate of a throw and wall-rebound catch test. The test involved 40 attempts of progressive increasing difficulty, as determined by increased distances from a wall and transitions from two-handed to one-handed catches. Outcomes were treated as quasi-binomial and modelled by generalised linear mixed logistic regression analysis. EHC improved with age from childhood to mid-adolescence, although boys were more adept at each age (p < 0.001). The patterns of change in EHC with increasing age varied according to the degree of difficulty of the task (p < 0.001); throw and two-handed catch proficiency developing earlier than throw and one-handed catch in both sexes. Boys’ EHC was better than girls’ as early as age 8 years and male proficiency was maintained through to mid-adolescence. The proficiency of throw and two-handed catch rates developed faster than throw and one-handed catch rates for both sexes.     

The effects of aerobic- versus strength-training on body image among young women with pre-existing body image concerns

This experiment compared the effects of aerobic-training (AT) versus strength-training (ST) on body image among young women with pre-existing body image concerns. Theory-based correlates of body image change were also examined. Participants were 46 women (M age = 21.5 years), randomly assigned to an 8-week AT or ST intervention consisting of supervised exercise 3 days/week. Multidimensional measures of body image were administered pre- and post-intervention, along with measures of physical fitness, perceived fitness, and exercise self-efficacy. Women in the AT condition reported greater reductions in social physique anxiety (p = .001) and tended to report greater improvements in appearance evaluation (p = .06) than women in the ST condition. Changes in perceived fatness, perceived aerobic endurance and aerobic self-efficacy were significantly correlated with body image change (ps < .003). Results provide direction for prescribing exercise to improve body image and advancing theory to account for the effects of exercise.     

Do intermediate- and higher-order principal components contain useful information to detect subtle changes in lower extremity biomechanics during running?

Recently, a principal component analysis (PCA) approach has been used to provide insight into running pathomechanics. However, researchers often account for nearly all of the variance from the original data using only the first few, or lower-order principal components (PCs), which are often associated with the most dominant movement patterns. In contrast, intermediate- and higher-order PCs are generally associated with subtle movement patterns and may contain valuable information about between-group variation and specific test conditions. Few investigations have evaluated the utility of intermediate- and higher-order PCs based on observational cross-sectional analyses of different cohorts, and no prior studies have evaluated longitudinal changes in an intervention study. This study was designed to test the utility of intermediate- and higher-order PCs in identifying differences in running patterns between different groups based on three-dimensional bilateral lower-limb kinematics. The results reveal that differences between sex- and age-groups of 128 runners were observed in the lower- and intermediate-order PCs scores (p < 0.05) while differences between baseline and following a 6-week muscle strengthening program for 24 runners with patellofemoral pain were observed in the higher-order PCs scores (p < 0.05), which exhibited a moderate correlation with self-reported pain scores (r = −0.43; p < 0.05).     

Evolution of match performance parameters for various playing positions in the English Premier League

This study aimed to investigate position-specific evolution of physical and technical performance parameters in the English Premier League (EPL). Match performance observations (n = 14700) were collected using a multiple-camera computerized tracking system across seven seasons (2006–07 to 2012–13). Data were analyzed relative to five playing positions: central defenders (n = 3792), full backs (n = 3420), central midfielders (n = 3200), wide midfielders (n = 2136) and attackers (n = 2152). High-intensity running distance increased in the final season versus the first season in all playing positions (p < .05, ES: 0.9–1.3) with full backs displaying the greatest increase (∼36% higher in 2012–13). Similar trends were observed for sprint distance with full backs demonstrating the most pronounced increase across the seven seasons (36–63%, p < .001, ES: 0.8–1.3). Central players (central defenders and midfielders) illustrated the most pronounced increases in total passes and pass success rate (p < .05, ES: 0.7–0.9) whilst wide players (full backs and wide midfielders) demonstrated only small-moderate increases in total passes and pass success rate (p < .05, ES: 0.6–0.8). The data demonstrates that evolving tactics in the EPL have impacted on the physical demands of wide players and the technical requirements of central players. These findings could be used for talent identification or position-specific physical and technical training.     

Increased forefoot loading is associated with an increased plantar flexion moment

The aim of this study was to identify the cascade of effects leading from alterations in force generation around the ankle joint to increased plantar pressures under the forefoot. Gait analysis including plantar pressure measurement was performed at an individually preferred and a standardized, imposed gait velocity in diabetic subjects with polyneuropathy (n = 94), without polyneuropathy (n = 39) and healthy elderly (n = 19). The plantar flexion moment at 40% of the stance phase was negatively correlated with the displacement rate of center of pressure (r = ?.749, p < .001 at the imposed, and r = ?.693, p < .001 at the preferred gait velocity). Displacement rate of center of pressure was strongly correlated with forefoot loading (r = ?.837, p < .001 at the imposed, and r = ?.731, p < .001 at the preferred gait velocity). People with a relatively high plantar flexion moment at 40% of the stance phase, have a faster forward transfer of center of pressure and consequently higher loading of the forefoot. This indicates that interventions aimed at increasing the control of the roll-off of the foot may contribute to a better plantar pressure distribution.     

Maternal postpartum depressive symptoms and infant externalizing and internalizing behaviors

Maternal postpartum depression has been shown to be one of the main predictors of externalizing and internalizing behaviors in toddlers and adolescents. Research suggests that presence of such behaviors can be observed as early as infancy. The current study uses longitudinal data from 247 mothers to examine the relationship between postpartum depressive symptoms at 8 weeks and the infant's externalizing and internalizing behaviors at 12 months. In unadjusted linear regression models, there were associations between postpartum depressive symptoms and infant externalizing behaviors (β = 0.082, SE = 0.032, p = 0.012) and internalizing behaviors (β = 0.111, SE = 0.037, p = 0.003). After controlling for potential confounding factors, including maternal age, race, education, home ownership, smoking status in the postpartum period, marital status, parenting stress, and happiness from becoming a parent, the associations between postpartum depressive symptoms and infant externalizing (β = 0.051, SE = 0.034, p = 0.138) and internalizing behaviors (β = 0.077, SE = 0.040, p = 0.057) were reduced and became non-significant. Furthermore, in these models the total amount of variance explained was 17.2% (p < 0.0001) for externalizing behaviors and 10.5% (p < 0.01) for internalizing behaviors; the only significant predictor of externalizing behaviors was maternal age (β = −0.074, SE = 0.030, p = 0.014), and of internalizing behaviors was white non-Hispanic ethnicity (β = −1.33, SE = 0.378, p = 0.0005). A combined effect of the confounding factors seems to explain the finding of no significant independent association between postpartum depressive symptoms and infant externalizing and internalizing behaviors.     

Motivational characteristics of obese adolescents toward physical activity: Contribution of self-determination theory

IntroductionRegular physical activity (PA) practice represents a key component of obesity treatment.ObjectiveBased on self-determination theory (SDT), this cross-sectional study aimed to explore the motivational characteristics associated with PA practice among obese adolescents.MethodOne hundred and five overweight or obese adolescents (mean age = 15 years old, SD = 2.69) were questioned about their level of PA, motivational regulations toward PA and level of satisfaction of basic psychological needs.ResultsData revealed that satisfaction of autonomy and relatedness needs is positively associated with autonomous forms of motivation (e.g., for integrated regulation β = .44; and 0.35, respectively, p < .01). Otherwise, non-satisfaction of the needs of autonomy and competence is associated with the most controlled forms of motivation (e.g., for external regulation β = −.27, p < .01; and −.18, p < .05, respectively). In turn, a high level of identified regulation, a low level of external regulation and a high level of satisfaction of the need for competence are associated with weekly PA (β = .28; −.19 and .24, respectively, p < .05).ConclusionSDT appears as an interesting theoretical framework to explore motivational antecedents of PA among obese adolescents.     

Effects of different swimming race constraints on turning movements

The aim of this study was to investigate the effects of different swimming race constraints on the evolution of turn parameters. One hundred and fifty-eight national and regional level 200-m (meters) male swimming performances were video-analyzed using the individualized-distance model in the Open Comunidad de Madrid tournament. Turn (p < .001, ES = 0.36) and underwater distances (p < .001, ES = 0.38) as well as turn velocity (p < .001, ES = 0.69) significantly dropped throughout the race, although stroke velocity and underwater velocity were maintained in the last lap of the race (p > .05). Higher expertise swimmers obtained faster average velocities and longer distances in all the turn phases (p < .001, ES = 0.59), except the approach distance. In addition, national level swimmers showed the ability to maintain most of the turn parameters throughout the race, which assisted them in improving average velocity at the end of races. Therefore, the variations in the turning movements of a swimming race were expertise-related and focused on optimizing average velocity. Turning skills should be included in the swimming race action plan.     

The effect of a motor skills training program in the improvement of practiced and non-practiced tasks performance in children with developmental coordination disorder (DCD)

The purpose of the present study was to examine the effect of a group-based task oriented skills training program on motor and physical ability for children with DCD. It was also investigated if there was an effect on fine motor and handwriting tasks that were not specifically practiced during the training program. Forty-one children aged 6–10 years took part in this study. Children were assigned to three groups: an experimental training group consisting of 14 children with DCD, a control non-training group consisted of 13 children with DCD and a control non-training group consisting of 14 typically developed children. The measurements included were, the Movement Assessment Battery for Children (MABC), the Modified Agility Test (MAT), the Triple Hop Distance (THD), the 5 Jump-test (5JT) and the Handwriting Performance Test. All measures were administered pre and post an 8-week training program. The results showed that 10 children of the DCD training-group improved their performance in MABC test, attaining a score above the 15th percentile after their participation in the training program. DCD training-group showed a significant improvement on all cluster scores (manual dexterity (t (13) = 5.3, p < .001), ball skills (t (13) = 2.73, p < .05) and balance (t (13) = 5.13, p < .001). Significant performance improvements were also found in MAT, THD, 5JT (t (13) = –4.55; p < .01), handwriting quality (t (12) = –2.73; p < .05) and speed (t (12) = –4.2; p < .01) after the training program. In conclusion, improvement in both practiced and non-practiced skills, in the training program, may reflect improvement in motor skill but also transfer to other skills.