Comparison of trunk muscle reflex activation patterns between active and passive trunk flexion–extension loading conditions

The aim of the present study was to determine the effects of trunk flexion–extension loading on the neuromuscular reflexive latencies and amplitude responses of the trunk musculature. Eighteen male and female subjects (18–27 yrs) participated in active and passive trunk flexion extension, performed ∼7 days apart. Subjects performed 60 trunk flexion–extension repetitions. Surface electromyography (EMG) was collected bilaterally from paraspinal and abdominal muscles. In the active condition, subjects volitionally moved their trunks, while in the passive condition the dynamometer controlled the movements. The trunk was perturbed before and immediately after 30 repetitions. Latency of muscle onset, latency of first peak, latency of maximum peak, and peak EMG amplitude were evaluated. No differences between conditions, sides, or perturbation session were apparent. Overall latencies were shorter in females (p < .05) and abdominal muscles compared to paraspinals (p < .05). Thoracic paraspinal muscle amplitudes were greater than all other muscles (p < .05). Based upon the present results, the neuromuscular system engages trunk flexor muscles prior to the paraspinals in order to provide possible stabilization of the trunk when flexor moments are generated. Overall, the results indicate no difference in response of the neuromuscular system to active or passive repetitive loading.     

Different coordination and flexibility of the spine and pelvis during lateral bending between young and older adults

This study examined coordination of the spine and pelvis during lateral bending of the trunk in older adults. Thirty-four healthy subjects (17 young and 17 older adults) demonstrated lateral bending at a controlled speed while holding a bar at approximately 180 degrees of shoulder flexion. Kinematic data collection was completed on the thoracic spine, lumbar spine, and pelvis. The coupling angle was calculated to examine the thorax–lumbar, lumbar–pelvis, and thorax–pelvis coordination patterns. The older adults demonstrated a reduced range of motion (ROM) of the lumbar spine, while both groups revealed similar ROM in the thorax and in the pelvis. The coupling angle between the straightening and bending phases was different only for the older adults in the thorax–lumbar (23.4 ± 8.0 vs. −1.6 ± 4.4, p = 0.004) and the lumbar–pelvis (65.4 ± 7.2 vs. 86.1 ± 7.8, p = 0.001) coordination. However, there was no group difference in the thorax–pelvis coordination. These findings indicate that age-related changes in the lumbar region affect coordination patterns only during the bending phase. The older adults preserved a similar pattern of movement to the young adults during the straightening phase, but the coordination variability of the coupling angles was greater for the older adults than for the young adults. This movement pattern suggests that the older adults lacked consistent trunk control in an attempt to optimize lateral bending coordination.     

Spinal kinematics during gait in healthy individuals across different age groups

Most studies investigating trunk kinematics have not provided adequate quantification of spinal motion, resulting in a limited understanding of the healthy spine’s biomechanical behavior during gait. This study aimed at assessing spinal motion during gait in adolescents, adults and older individuals.Fourteen adolescents (10–18 years), 13 adults (19–35 years) and 15 older individuals (≥65 years) were included. Using a previously validated enhanced optical motion capture approach, sagittal and frontal plane spinal curvature angles and general trunk kinematics were measured during shod walking at a self-selected normal speed.Postural differences indicated that lumbar lordosis and thoracic kyphosis increase throughout adolescence and reach their peak in adulthood. The absence of excessive thoracic kyphosis in older individuals could be explained by a previously reported subdivision in those who develop excessive kyphosis and those who maintain their curve. Furthermore, adults displayed increased lumbar spine range of motion as compared to the adolescents, whereas the increased values in older individuals were found to be related to higher gait speeds. This dataset on the age-related kinematics of the healthy spine can serve as a basis for understanding pathological deviations and monitoring rehabilitation progression.     

Making sense of age-related distractibility: The critical role of sensory modality

Older adults are known to have reduced inhibitory control and therefore to be more distractible than young adults. Recently, we have proposed that sensory modality plays a crucial role in age-related distractibility. In this study, we examined age differences in vulnerability to unimodal and cross-modal visual and auditory distraction. A group of 24 younger (mean age = 21.7 years) and 22 older adults (mean age = 65.4 years) performed visual and auditory n-back tasks while ignoring visual and auditory distraction. Whereas reaction time data indicated that both young and older adults are particularly affected by unimodal distraction, accuracy data revealed that older adults, but not younger adults, are vulnerable to cross-modal visual distraction. These results support the notion that age-related distractibility is modality dependent.     

Applying an active lumbopelvic control strategy during lumbar extension exercises: Effect on muscle recruitment patterns of the lumbopelvic region

ObjectiveExamine whether implementing an active lumbopelvic control strategy during high load prone lumbar extension exercises affects posterior extensor chain recruitment and lumbopelvic kinematics.MethodsThirteen healthy adults acquired an optimal active lumbopelvic control strategy during guided/home-based training sessions. During the experimental session electromyography was used to evaluate the activity of the posterior extensor chain muscles during high load trunk/bilateral leg extension exercises with/without application of the strategy. Video-analysis was used to evaluate thoracic/lumbar/hip angles.ResultsImplementing the active lumbopelvic control strategy decreased the lordotic angle during trunk (p = 0.045; −3.2°) and leg extension exercises (p = 0.019; −10°). The hip angle was solely affected during trunk extension (p < 0.001; +9.2°). The posterior extensor chain (i.e. mean of the relative activity of all muscles (%MVIC) was recruited to a higher extent (p = 0.026; +9%) during trunk extension exercises performed with active lumbopelvic control. Applying the strategy during leg extension exercises lead to less activity of longissimus thoracic (p = 0.015; −10.2%) and latissimus dorsi (p = 0.010; −4.4%), and increased gluteus maximus activity (p ≤ 0.001; +16.8%).ConclusionsWhen healthy people are taught/instructed to apply an active lumbopelvic control strategy, this will decrease the degree of lumbar (hyper)lordosis and this influences the recruitment patterns of trunk and hip extensors. Hence, the possible impact on predetermined training goals should be taken into account by trainers.     

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).     

Age-related differences in the timing aspect of lumbopelvic rhythm during trunk motion in the sagittal plane

Forward bending and backward return of the human trunk in the sagittal plane are associated with a specific lumbopelvic rhythm, which consists of magnitude and timing aspects. In this study, the age-related differences in the timing aspect of lumbopelvic rhythm were investigated using the continuous relative phase method. Specifically, the mean absolute relative phase (MARP) between the thoracic and pelvic motions as well as variation in MARP under repetitive motions, denoted by deviation phase (DP), were characterized in sixty participants between 20 and 70 years old. MARP and DP were determined for trunk forward bending and backward return tasks with self-selected slow and fast paces. The MARP and DP were both smaller (p = 0.003, p < 0.001 respectively) in the older versus younger age participants with no gender-related difference. In fast versus slow pace task, the MARP was smaller (p < 0.001) only in forward bending, whereas the DP was smaller (p < 0.001) in both the forward bending and backward return. A more in-phase and more stable lumbopelvic rhythm denoted respectively by smaller MARP and DP in older versus younger individuals maybe a neuromuscular strategy to protect the lower back tissues from excessive strain, in order to reduce the risk of injury.     

The influence of age,anxiety and concern about falling on postural sway when standing at an elevated level

Psychological processes may influence balance and contribute to the risk of falls in older people. While a self-reported fear of falling is associated with increased postural sway, inducing fear using an elevated platform can lead to reduced sway, suggesting different underlying mechanisms whereby fear may influence balance control. This study examined changes in postural sway, muscle activity and physiological measures of arousal while standing on a 65 cm elevated platform, compared to floor level, in young and older adults. The older adults were classified as fall concerned or not fall concerned based on the Falls Efficacy Scale-International and anxious or not anxious based on the Goldberg Anxiety Scale. Fall concern did not affect the physiological and sway response to the elevated platform. In response to the postural threat, the anxious participants increased their sway frequency (p = 0.001) but did not reduce sway range (p = 0.674). Conversely, non-anxious participants showed an adaptive tightening of balance control, effectively reducing sway range in the elevated condition (p < 0.001). Generalised anxiety in older adults appears to differentially affect postural control strategies under threatening conditions.     

Aging effect on detectability,criticality and urgency under various auditory conditions

The objective of the study was to investigate the relationship between different components of an auditory warning signal and determine elderly driver’s detection, criticality and urgency perceptions under varied auditory warning conditions. A laboratory study was conducted involving 28 younger and 28 older adults. A pure-tone audiogram was administered for quantification of the participant’s hearing level (in dBHL) prior to the test protocols. Audiogram was conducted in a sound isolated booth. The main experiment investigated the effects of frequency, temporal characteristics, aging, and noise on detectability, caution and perceived urgent levels. Method of adjustment was used by the subjects to adjust the sound pressure level (dBA) till they detected, or felt caution or urgent. Overall, the results indicated that elderly had higher sound pressure threshold than younger individuals in all the sessions (i.e., detectability, caution and urgency). Elderly were found to have higher hearing thresholds especially at 4000 Hz. Higher frequencies were also seen to require less sound pressure thresholds to convey feeling of caution and urgency. Sound pressure threshold to convey the feeling of urgency was the lowest for 2000 Hz and 4000 Hz with 1000 Hz requiring the highest threshold intensity. In conclusion, current study findings suggest frequency, temporal and spectral components to influence a person’s criterion. We would recommend the use of complex tones (multi-components) having high frequency around 2000 Hz for detection, warning and urgent conditions.     

Through babies’ eyes: Practical and theoretical considerations of using wearable technology to measure parent–infant behaviour from the mothers’ and infants’ view points

AimsTo explore the utility of first-person viewpoint cameras at home, for recording mother and infant behaviour, and for reducing problems associated with participant reactivity, which represent a fundamental bias in observational research.MethodsWe compared footage recording the same play interactions from a traditional third-person point of view (3rd PC) and using cameras worn on headbands (first-person cameras [1st PCs]) to record first-person points of view of mother and infant simultaneously. In addition, we left the dyads alone with the 1st PCs for a number of days to record natural mother–child behaviour at home. Fifteen mothers with infants (3–12 months of age) provided a total of 14 h of footage at home alone with the 1st PCs.ResultsCodings of maternal behaviour from footage of the same scenario captured from 1st PCs and 3rd PCs showed high concordance (kappa >0.8). Footage captured by the 1st PCs also showed strong inter-rater reliability (kappa = 0.9). Data from 1st PCs during sessions recorded alone at home captured more ‘negative’ maternal behaviours per min than observations using 1st PCs whilst a researcher was present (mean difference = 0.90 (95% CI 0.5–1.2, p < 0.001 representing 1.5 SDs).Conclusion1st PCs offer a number of practical advantages and can reliably record maternal and infant behaviour. This approach can also record a higher frequency of less socially desirable maternal behaviours. It is unclear whether this difference is due to lack of need of the presence of researcher or the increased duration of recordings. This finding is potentially important for research questions aiming to capture more ecologically valid behaviours and reduce demand characteristics.     

Life span changes: Performing a continuous 1:2 bimanual coordination task

The experiment was conducted to determine the influence of mirror movements in bimanual coordination during life span. Children, young adults, and older adults were instructed to perform a continuous 1:2 bimanual coordination task by performing flexion–extension wrist movements over 30 s where symmetrical and non-symmetrical coordination patterns alternate throughout the trial. The vision of the wrists was covered and Lissajous-feedback was provided online. All age groups had to perform 10 trials under three different load conditions (0 kg, .5 kg, 1.0 kg: order counterbalanced). Load was manipulated to determine if increased load increases the likelihood of mirror movements. The data indicated that the performance of the young adults was superior compared to the children and older adults. Children and older adults showed a stronger tendency to develop mirror movements and had particular difficulty in performing the non-symmetrical mode. This type of influence may be attributed to neural crosstalk.     

Technique determinants of knee joint loads during cutting in female soccer players

The aim of this study was to investigate the relationships between technique characteristics and knee abduction moments during 90° cuts. A cross sectional design involving 26 elite and sub-elite female soccer players (mean ± SD; age: 21 ± 3.2 years, height: 1.68 ± 0.07 m, and mass: 59.1 ± 6.8 kg) was used to explore relationships between pre-determined technical factors on knee abduction moments during cutting. Three dimensional motion analyses of 90° cuts on the right leg were performed using ‘Qualisys Pro Reflex’ infrared cameras (240 Hz). Ground reaction forces were collected from two AMTI force platforms (1200 Hz) embedded into the running track to examine 2nd last and last footfalls. Pearson’s correlation coefficients, co-efficients of determination and hierarchical multiple regression were used to explore relationships between a range of technique parameters and peak knee abduction moments. Significance was set at p < .05. Hierarchical multiple regression revealed that initial knee abduction angle, lateral leg plant distance and initial lateral trunk lean could explain 67% (62% adjusted) of the variation in peak knee abduction moments (F_(1,22) = 8.869, p = .007). These findings reveal potential modifiable technical factors to lower peak knee abduction moments during cutting.     

Asymmetrical loading affects intersegmental dynamics during the swing phase of walking

Much of the work related to lower extremity inertia manipulations has focused on temporal, kinematic and traditional inverse dynamics assessments during locomotion. Intersegmental dynamics is an analytical technique that provides further insights into mechanisms underlying linked-segment motion. The purpose of this study was to determine how intersegmental dynamics during the swing phase of walking are altered during asymmetrical lower extremity loading. Participants walked overground at a speed of 1.57 m s^?1 with 0, 0.5, 1.0, and 2.0 kg attached to one foot. Net, interaction, gravitational, and muscle moments were computed. Moment magnitudes at joints of the loaded leg increased systematically with increasing load, whereas unloaded leg moments were unaffected by loading. With increasing load, relative contributions of interaction moments about the knee and hip and gravitational moment about the ankle increased (i.e., 21%, 8%, and 44% increases, respectively), whereas the relative contributions of muscle moments about all three joints declined (i.e., ?4%, ?13%, and ?8% decreases for the ankle, knee, and hip, respectively for unloaded vs. 2.0 kg). These results suggest that altered inertia properties of the limb not only affected the amount of muscular effort required to swing the leg, but also changed the nature of the interaction between segments.     

High- compared to low-arched athletes exhibit smaller knee abduction moments in walking and running

High- (HA) and low-arched athletes (LA) experience distinct injury patterns. These injuries are the result of the interaction of structure and biomechanics. A suggested mechanism of patellofemoral pain pertains to frontal plane knee moments which may be exaggerated in LA athletes. We hypothesize that LA athletes will exhibit greater peak knee abduction moments than high-arched athletes.MethodsTwenty healthy female recreational athletes (10 HA and 10 LA) performed five over-ground barefoot walking and five barefoot running trials at a self-selected velocity while three-dimensional kinematics and ground reaction forces were recorded. Peak knee abduction moments and time-to-peak knee abduction moments were calculated using Visual 3D.ResultsHigh-arched athletes had smaller peak knee abduction moments compared to low-arched athletes during walking (KAM1: p = 0.019; KAM2: p = 0.015) and running (p = 0.010). No differences were observed in time-to-peak knee abduction moment during walking (KAM1: p = 0.360; KAM2: p = 0.085) or running (p = 0.359).ConclusionsThese findings demonstrate that foot type is associated with altered frontal plane knee kinetics which may contribute to patellofemoral pain. Future research should address the efficacy of clinical interventions including orthotics and rehabilitation programs in these athletes.     

A genetic variant (COMT) coding dopaminergic activity predicts personality traits in healthy elderly

Association studies between the NEO five factor personality inventory and COMT rs4680 have focused on young adults and the results have been inconsistent. However, personality and cortical changes with age may put older adults in a more sensitive range for detecting a relationship. The present study examined associations of COMT rs4680 and personality in older adults.Genetic association analyses were carried out between the NEO and the targeted COMT rs4680 in a large, well-characterized sample of healthy, cognitively normal older adults (N = 616, mean age = 69.26 years).Three significant associations were found: participants with GG genotype showed lower mean scores on Neuroticism (p = 0.039) and higher scores on Agreeableness (p = 0.020) and Conscientiousness (p = 0.006) than participants with AA or AG genotypes.These results suggest that older adults with higher COMT enzymatic activity (GG), therefore lower dopamine level, have lower Neuroticism scores, and higher Agreeableness and Conscientiousness scores. This is consistent with a recent model of phasic and tonic dopamine release suggesting that even though GG genotype is associated with lower tonic dopamine release, the phasic release of dopamine might be optimal for a more adaptive personality profile.     

Postural stability with exhaustive repetitive sit-to-stand exercise in young adults

Previous research has indicated that muscle fatigue due to repeated bouts of physical activity can have negative residual effects on balance; however investigations using multi-joint forms of exercise involved in everyday settings and determination of how control of posture is altered during the physical activity itself are limited. The purpose of this investigation was to evaluate alterations in postural stability before, during, and after prolonged multi-joint STS exercise in healthy young adults. Center of pressure (COP) acquisitions were collected during repetitive STS exercise, while voluntary limits of stability (LOS) testing was performed before, immediately after, and 10 min after STS exercise. By 50% total STS exercise time, fatigue resulted in increased anterio-posterior (y) and medio-lateral (x) COP path lengths (p = 0.003 and p = 0.018 respectively) and an anterior shift of COP at seat-off towards the mid-foot (p = 0.010). No significant change in LOS mean amplitude was found after STS exercise; however a significant fatigue effect resulted in increased COPy sway velocity at maximal lean positions (p = 0.006), but returned to PRE values after 10 min of rest. Declines in postural stability during repetitive STS exercise was associated with reduced control of COP, as well as a reduced ability to stably control COP at extreme postural limits; however, 10 min was adequate in young adults for recovery. These results may have important implications for monitoring fall risk due to acute bouts of exercise induced muscle fatigue from repetitive multi-joint activities such as the STS.     

Cycling strategies of young and older cyclists

This study concentrates on the cycling strategies of older cyclists (54–62 year olds) in comparison to young cyclists (20–30 year olds). While cycling in a safe laboratory set-up, controlled lateral perturbations are applied to the rear of the bicycle. Three possible strategies to keep balance are analysed for a young and older aged group: steering, lateral trunk movement and outward knee movement. Older subjects appear to rely more on knee movement as a control mechanism than young subjects. Furthermore, the frequency domain analysis revealed that the older adults need more effort to counteract high frequency perturbations. Increased inter-individual variation for the older adults subject group suggests that this group can be seen as a transition group in terms of physical fitness. This explains their increased risk in single-sided bicycle accidents (i.e. accidents involving the cyclist only). Therefore, older cyclists could benefit from improving the stability of cycling at lower speeds.     

Modulating younger and older adults’ performance in ignoring pictorial information during a word matching task

Using both behavioural and event-related potential (ERP) data, the current study sought to examine the neurophysiological underpinnings for the effect of distracting pictorial information on semantic word matching performance in younger and older adults. This was tested in the context of semantic relations between task-relevant word pairs, a task-irrelevant picture and the resultant N400 differences in ERP. Younger and older adults were shown a context word superimposed on a to-be-ignored picture, followed by a test word. Their task was to determine whether the prime and test words were semantically related. The to-be-ignored pictures were interfering (for ‘No’ trials), facilitating (for ‘Yes’ trials), or neutral (for both ‘Yes’ and ‘No’ trials) to the expected responses. The interfering and facilitatory effects of to-be-ignored pictures were assessed under more automatic and more controlled conditions by manipulating the context–test interstimulus-interval (ISI) as 50 ms and 1000 ms, respectively. The analysis of the N400 at centro-parietal sites during test word display revealed similar N400 amplitudes for the ‘No’ response trials at the two ISIs, suggesting that younger and older adults showed an equivalent effect from interfering pictures. In contrast, younger adults showed greater reductions in the N400, as compared to older adults, for ‘Yes’ trials indicating differential effects in facilitation from to-be-ignored pictorial information, but only in the long ISI condition. The data are discussed in terms of age differences in resource demanding strategy use during a semantic word matching task, specifically during controlled retrieval.     

Till depression do us part? Examining the prospective associations between depression and marital adjustment in older adults

IntroductionThe association between marital adjustment and depression in young couples is well established. However, little is known about the longitudinal associations between marital adjustment and depression in older adults.ObjectiveTo explore if such associations are significant in older adults and determine their direction of effects.MethodThe cross-sectional and 12-month prospective associations between diagnostic depression and marital adjustment in a representative sample of community-dwelling older adults (age ≥ 65 years, n = 847) from Quebec, Canada, were assessed through cross-lagged, multiple regression analyses.ResultsData suggest a cross-sectional association between marital adjustment and depression. As for longitudinal associations, marital adjustment predicted subsequent diagnostic depression but there was no support for the inverse path, suggesting a unidirectional relation between these variables.ConclusionWhile significant, the association between initial marital adjustment and later depression was weak. Based on our and previously reported findings, the importance of the prospective relations between marital quality and depression in older adults is discussed.     

An own-age bias in age estimation of faces

IntroductionAge estimation performances may be influenced by group biases.ObjectiveThis study investigated whether we are more accurate at estimating the age of people from one's own-age than the age of younger or older people.MethodChildren, young and older adults’ performances at estimating both in-group and out-group faces were compared.ResultsA significant “Age of participants” × “Age of face stimuli” interaction was revealed. Moreover, the age of children's faces was more accurately estimated than the age of young and older adults’ faces by the three groups of participants.ConclusionThe present results revealed the occurrence of an own-age bias for children, young and older adults in age estimation. Several explanations to this own-age effect are discussed.