Changes in movement organization and control strategies when learning a biomechanically constrained gait pattern, racewalking: a PCA study.

Combining advances from gait analysis and motor learning fields, this study aims to examine invariant characteristics and practice-related changes in the control of walking gait when learning a biomechanically constrained pattern, racewalking (RW). RW's regulation imposes a straightened knee at the stance phase which differentiates it qualitatively from normal walking. Using 3D motion analysis, we computed key kinematic variables from a whole-body model. Principal component analysis was then used as a tool to evaluate the evolution of normal walking synergies (S0) immediately at the first practice session (S1) and further with practice (S1-S4). Before the start of practice, normal walking was characterized by two predominant control dimensions explaining an upper-extremities/antero-posterior component (PC1) and a lower-extremities/vertical component (PC2). Compared to normal walking, the immediate increase at S1 in the number of PCs needed to explain a significant portion of movement variance could be suggestive of a recruitment of a task-specific component. With practice, the significant decrease in the variance accounted for by PC1 and in the correlations between many variables could indicate a destabilization of spontaneous tendencies to facilitate the adoption of more task-specific coordinative pattern. PC2 seemed to be reinforced with practice where a significant increase in its explained variance was observed. In sum, this study shows that common features in the gait control are preserved with practice, and the movement reorganization, however, seems rather defined by shifts in the relative contribution of some variables within each PC.

Development of information-movement couplings in a rhythmical ball-bouncing task: from space- to time-related information.

We studied the development of information-movement couplings in a ball-bouncing task with a special interest in how space- and time-related information is used by people of different ages. Participants from four age groups (children aged 7-8, 9-10 and 11-12 years, and adults) performed a virtual ball-bouncing task in which space- and time-related information were independently manipulated. Task performance and information-movement couplings were analyzed. Our results confirm a clear use of time-related information in adults, while children demonstrated a predominant relationship between space-related information and the period of movement. In the course of development, however, the children become progressively more capable of using time-related information in order to control the rhythmic ball-bouncing task. A second and weaker coupling, between ball height information and racket velocity at impact, also appears in the course of development. The data seem to show that the development of children follows the freezing-freeing-exploiting sequence proposed by Savelsbergh and Van der Kamp (Int J Sport Psychol 31:467-484, 2000), with a significant change in how information is used to control movement related to age.

Mixed control for perception and action: timing and error correction in rhythmic ball-bouncing.

The task of bouncing a ball on a racket was adopted as a model system for investigating the behavioral dynamics of rhythmic movement, specifically how perceptual information modulates the dynamics of action. Two experiments, with sixteen participants each, were carried out to definitively answer the following questions: How are passive stability and active stabilization combined to produce stable behavior? What informational quantities are used to actively regulate the two main components of the action-the timing of racket oscillation and the correction of errors in bounce height? We used a virtual ball-bouncing setup to simultaneously perturb gravity (g) and ball launch velocity (v b) at impact. In Experiment 1, we tested the control of racket timing by varying the ball's upward half-period t up while holding its peak height h p constant. Conversely, in Experiment 2, we tested error correction by varying h p while holding t up constant. Participants adopted a mixed control mode in which information in the ball's trajectory is used to actively stabilize behavior on a cycle-by-cycle basis, in order to keep the system within or near the passively stable region. The results reveal how these adjustments are visually controlled: the period of racket oscillation is modulated by the half-period of the ball's upward flight, and the change in racket velocity from the previous impact (via a change in racket amplitude) is governed by the error to the target.

Learning an energy-demanding and biomechanically constrained motor skill, racewalking: movement reorganization and contribution of metabolic efficiency and sensory information.

This study investigated how novices learn an energy demanding and biomechanically constrained task like racewalking. The first aim was to examine if movement reorganizes according to some fundamental strategies, proceeding in different stages (Newell, 1985). The second aim was to investigate the link between movement reorganization, metabolic efficiency and perceived exertion. Seven participants undertook seven racewalking learning sessions on a motorized treadmill, with increased velocity as the experiment progressed, in order to reach a goal performance speed of 10 kmh(-1). Peripheral/central perceived exertion ratings, kinematic and metabolic data were collected during the 1st, 4th, 6th and 7th session. Repeated-measures (Learning Session×Speed) ANOVAs on kinematic data showed a proximal-to-distal directional trend in movement reorganization, with significant practice-related changes in pattern coordination and decreased variability. Early movement reorganization occurred at the 1st session ("coordination stage") and progressed until the 4th session ("control stage") to reach a plateau. In contrast, metabolic efficiency and peripheral perceived exertion continued optimizing until the last session, probably occurring in concurrence with the control stage. Peripheral perceived exertion presented the highest correlation with the global movement reorganization variables suggesting that it could play a key role in guiding movement reorganization in the learning process, improving efficiency as a result.

Multidimensional predictors of fatigue among octogenarians and centenarians.

BACKGROUND: Fatigue is a common and frequently observed complaint among older adults. However, knowledge about the nature and correlates of fatigue in old age is very limited. OBJECTIVE: This study examined the relationship of functional indicators, psychological and situational factors and fatigue for 210 octogenarians and centenarians from the Georgia Centenarian Study. METHODS: Three indicators of functional capacity (self-rated health, instrumental activities of daily living, physical activities of daily living), two indicators of psychological well-being (positive and negative affect), two indicators of situational factors (social network and social support), and a multidimensional fatigue scale were used. Blocked multiple regression analyses were computed to examine significant factors related to fatigue. In addition, multi-group analysis in structural equation modeling was used to investigate residential differences (i.e., long-term care facilities vs. private homes) in the relationship between significant factors and fatigue. RESULTS: Blocked multiple regression analyses indicated that two indicators of functional capacity, self-rated health and instrumental activities of daily living, both positive and negative affect, and social support were significant predictors of fatigue among oldest-old adults. The multiple group analysis in structural equation modeling revealed a significant difference among oldest-old adults based on residential status. CONCLUSION: The results suggest that we should not consider fatigue as merely an unpleasant physical symptom, but rather adopt a perspective that different factors such as psychosocial aspects can influence fatigue in advanced later life.

Cognitive performance in centenarians and the oldest old: norms from the Georgia Centenarian Study.

We present normative data from a large population-based sample of centenarians for several brief, global neurocognitive tasks amenable for frail elders. Comparative data from octogenarians are included. A total of 244 centenarians and 80 octogenarians from Phase III of the Georgia Centenarian Study were administered the Mini-Mental Status Examination, Severe Impairment Battery, and Behavioral Dyscontrol Scale. Centenarians (age 98-107) were stratified into three age cohorts (98-99, 100-101, 102-107), octogenarians into two 5- year cohorts (80-84, 85-89). Highly significant differences were observed between groups on all measures, with greater variation and dispersion in performance among centenarians, as well as stronger associations between age and performance. Descriptive statistics and normative ranges (unweighted and population-weighted) are provided by age cohort. Additional statistics are provided by education level. While most previous centenarian studies have used convenience samples, ours is population-based and likely more valid for comparison in applied settings. Results suggest centenarians look different than do even the oldest age range of most normative aging datasets (e.g., 85-90). Results support using global measures of neurocognition to describe cognitive status in the oldest old, and we provide normative comparisons to do so.

Family history and adaptation among centenarians and octogenarians.

BACKGROUND: The purpose of this study was to analyze various 'family history' variables (i.e. childhood health, financial situation while growing up, living with grandparents before age 17, and number of children) among participants of the Georgia Centenarian Study. OBJECTIVE: To determine whether family history variables predict critical outcome areas such as cognitive functioning, activities of daily living, mental health, and economic dependence. METHODS: A total of 318 older adults (236 centenarians and 82 octogenarians) were assessed with regard to their mental status, ADL (activities of daily living) functioning, depression, family history, loneliness, and perceived economic status. RESULTS: Analyses indicated that the number of children significantly predicted the ability to engage in activities of daily living and loneliness. In essence, the more children, the higher the activities of the daily living score and the lower the loneliness scores. In addition, childhood health significantly predicted loneliness. The poorer one's health in childhood, the higher the loneliness scores. CONCLUSION: The results of this study confirm the importance of distal family history variables on present-day functioning.

Predicting happiness among centenarians.

BACKGROUND: Happiness is believed to evolve from the comparison of current circumstances relative to past achievement. However, gerontological literature on happiness in extreme old age has been limited. OBJECTIVE: The purpose of this study was to determine how perceptions of health, social provisions, and economics link past satisfaction with life to current feelings of happiness among persons living to 100 years of age and beyond. METHODS: A total of 158 centenarians from the Georgia Centenarian Study were included to conduct the investigation. Items reflecting congruence and happiness from the Life Satisfaction Index were used to evaluate a model of happiness. Pathways between congruence, perceived economic security, subjective health, perceived social provisions, and happiness were analyzed using structural equation modeling. RESULTS: Congruence emerged as a key predictor of happiness. Furthermore, congruence predicted perceived economic security and subjective health, whereas perceived economic security had a strong influence on subjective health status. CONCLUSION: It appears that past satisfaction with life influences how centenarians frame subjective evaluations of health status and economic security. Furthermore, past satisfaction with life is directly associated with present happiness. This presents implications relative to understanding how perception of resources may enhance quality of life among persons who live exceptionally long lives.

Distal and proximal resource influences on economic dependency among the oldest old.

BACKGROUND: As exceptional survivors, centenarians may have characteristics that reduce their dependency on family and community support systems despite the expectation that their extreme age creates a burden on those systems. The Georgia Centenarian Study obtained information about assistance for income, medical care, and caregiving of all types for a sample of centenarians and octogenarians. Previous studies have not established which characteristics may contribute to economic dependency among the oldest old. OBJECTIVE: To identify distal and proximal resource influences on economic dependency, considering past lifestyle, proximal health, economic resources, personality, and coping behavior. METHODS: Analysis sample sizes ranged from 109 to 138 octogenarians and centenarians. Blockwise multiple regressions predicted whether they received income assistance, number of medical care events, number of caregiving types, and total caregiving hours. RESULTS: Past life style, gender, ethnicity, socioeconomic status, functional health, and coping were not related to economic dependency. With the exception of the number of types of care, centenarians were not more dependent than octogenarians. Cognitive ability had the strongest effects for medical care and caregiving services. 'Extraversion', 'ideas', 'neuroticism', and 'competence' personality factors had significant effects for caregiving types and total hours of care received. CONCLUSION: Monitoring and intervention to maintain cognitive ability are critical practices for autonomy and reduced economic dependency among the oldest old. Psychological resources are more important influences on social support than functional health and other proximal economic resources.

Social resources and longevity: findings from the Georgia centenarian study.

BACKGROUND: As the proportion of adults aged 85 and older increases, investigations of resources essential for adapting to the challenges of aging are required. OBJECTIVE: To comprehensively investigate the social resources of cognitively intact centenarians participating in the Georgia Centenarian Study and the association between these resources and residence status. METHODS: Two widely used measures of social resources were investigated among participants living in private homes, personal care facilities, and nursing homes. Logistic regression was used to determine significant predictors of nursing home residence. RESULTS: Differences in levels of social resources were found between centenarians and octogenarians, and among centenarians in different living situations. Analyses revealed differential findings between self- and proxy reports. Controlling for education, activities of daily living, and financial ability to meet needs, only one of the two social resources measures significantly reduced the odds of nursing home residence. CONCLUSION: The findings of this study add to the existing literature on one of the basic adaptive resources (social resources) for centenarians. Whether a more specific assessment of network contact is employed, or a more global assessment is used, differences in these constructs exist between centenarians and octogenarians, among centenarians in differing living conditions, and across types of informants. Researchers examining the different resources that may contribute to extraordinary longevity and positive adaptation may find it essential to differentiate between the oldest old and centenarians, and to account for differences based upon measure, reporter type, and centenarian residence status.

Positive affect is associated with cardiovascular reactivity, norepinephrine level, and morning rise in salivary cortisol.

Positive affect was examined as a predictor of (1) cardiovascular reactivity during a sadness and an anger recall task and recovery following the protocol, (2) epinephrine (EPI) and norepinephrine (NOREPI) reactivity and level during the recall protocol, and (3) the diurnal pattern of salivary cortisol. Sample was 328 individuals. Negative affect, age, race, sex, smoking status, income, and BMI were adjusted. During sadness recall, positive affect was inversely related to systolic blood pressure (p=.007) and diastolic blood pressure (p=.049) reactivity, and unrelated to heart rate (p=.226). Positive affect was unrelated to reactivity during anger recall (ps>.19), and was unrelated to recovery at the end of the recall protocol. Positive affect was inversely related to the mean level of NOREPI (p=.046), and unrelated to EPI (p=.149). Positive affect was inversely related to the increase in cortisol 30 min post awakening (p=.042), and unrelated to the evening decline in cortisol levels (p=.174). Positive emotions may be relevant to good health.

Reproduction of self-rotation duration.

The vestibular system detects the velocity of the head even in complete darkness, and thus contributes to spatial orientation. However, during vestibular estimation of linear passive self-motion distance in darkness, healthy human subjects mainly rely on time, and they replicate also stimulus duration when required to reproduce previous self-rotation. We then made the hypothesis that the perception of vestibular-sensed motion duration is embedded within encoding of motion kinetics. The ability to estimate time during passive self-motion in darkness was examined with a self-rotation reproduction paradigm. Subjects were required to replicate through self-driven transport the plateau velocity (30, 60 and 90 degrees /s) and duration (2, 3 and 4s) of the previously imposed whole-body rotation (trapezoid velocity profile) in complete darkness; the rotating chair position was recorded (500 Hz) during the whole trials. The results showed that the peak velocity, but not duration, of the plateau phase of the imposed rotation was accurately reproduced. Suspecting that the velocity instruction had impaired the duration reproduction, we added a control experiment requiring subjects to reproduce two successive identical rotations separated by a momentary motion interruption (MMI). The MMI was of identical duration to the previous plateau phase. MMI duration was fidelitously reproduced whereas that of the plateau phase was hypometric (i.e. lesser reproduced duration than plateau) suggesting that subjective time is shorter during vestibular stimulation. Furthermore, the accurate reproduction of the whole motion duration, that was not required, indicates an automatic process and confirms that vestibular duration perception is embedded within motion kinetics.

The relationship between hostility and behavioral risk factors for poor health in women veterans.

BACKGROUND: While previous research has generally supported a relationship between hostility and health risk behaviors, the majority of this research has been conducted in predominately male, highly educated, Caucasian samples. The current study was designed to further examine the relationship between hostility and health risk behaviors in a sample of women. METHODS: Measures of health risk behavior and scores from the Cook-Medley hostility scale were obtained from 409 women veterans. Linear and logistic regression analyses were used to examine the relationship between hostility and health behaviors including tobacco smoking, alcohol use, body-mass index, caffeine use, and level of physical activity, after sociodemographic factors were accounted for. RESULTS: In a cohort of women veterans using VA health care, ages 35-81, hostility was significantly associated with tobacco smoking (OR = 2.10; 95% CI = 1.34 to 3.30), caffeine use (OR = 2.12; 95% CI = 1.16 to 3.85), and the number of alcoholic beverages consumed by women who drink alcohol. Hostility was not associated with body mass index (OR = 1.15; 95% CI = 0.77 to 1.72) or a lack of physical exercise (OR = 0.89; 95% CI = 0.55 to 1.43). CONCLUSIONS: Results are generally consistent with previous research and support the relationship between hostility and health risk behaviors. Awareness that hostility contributes to risk behaviors and disease may help in the design of interventions aimed at risk reduction.

Racial differences in physician recommendation of hormone replacement therapy.

PURPOSE: Previous studies have suggested that black women may be less likely than white women to be offered and to take hormone replacement therapy (HRT). Thus, race and other factors associated with physician recommendation of HRT that may influence women's decisions about HRT were examined. METHODS: Data were from a baseline assessment of participants in a randomized controlled trial designed to evaluate the efficacy of a tailored decision-aid on HRT decision-making. We telephone interviewed 581 Durham women ages 45-54. The association of race and other factors with reported physician recommendation of HRT was tested using chi(2) and logistic regression analysis. RESULTS: Overall, 45% of women surveyed reported that their physician recommended HRT; black women were significantly less likely than white women to report being advised about HRT (35% vs. 48%, respectively, P < 0.005). Additional factors associated with being recommended HRT included older age, being postmenopausal, having had a hysterectomy, having thought about the benefits of HRT, and being satisfied with information about HRT. CONCLUSIONS: Black women are less likely than white women to receive physician recommendation of HRT. Racial differences in patient-provider communication about HRT exist and thus require greater diligence on the part of health care providers to minimize such a gap.

Depressive symptoms, menopausal status, and climacteric symptoms in women at midlife.

OBJECTIVE: Previous studies have found increased rates of depression in women aged 45 to 54 years, but the factors that influence these rates are not understood. It was assessed whether higher rates of depressive symptoms were associated with menopausal status, climacteric symptoms, and use of hormone replacement therapy. DESIGN: Cross-sectional survey. SETTING: Community sample. METHODS: Data are from 581 women ages 45 to 54 years who were interviewed by telephone between October 1998 and February 1999. MEASURES: Depression was measured with the abbreviated CES-D, a depressive symptoms screening measure. Women's reported perception of menopausal stage, frequency of periods in the preceding 12 months, and history of oophorectomy were used to classify their menopausal status into four categories: (1) no indication of menopause; (2) close to menopause; (3) had begun menopause; and (4) had completed menopause. RESULTS: There were 168 women (28.9%) who reported a high level (> or = 10) of depressive symptoms when the abbreviated CES-D was used. In a logistic-regression analysis, significant factors associated with increased depressive symptoms included physical inactivity, inadequate income, use of estrogen/progesterone combination, and presence of climacteric symptoms (trouble sleeping, mood swings, or memory problems). Menopausal status was not associated with depressive symptoms. CONCLUSIONS: In this sample of women age 45 to 54 years, climacteric symptoms but not menopausal status were associated with higher rates of depressive symptoms.

Are the salutogenic effects of social supports modified by income? A test of an "added value hypothesis".

Older adults (54 men, 113 women; M age = 69.5 years) were examined to test the hypothesis that social supports would be more salutogenic (health promoting) for persons with lower incomes than for persons with higher incomes. Interactions of income and social supports (mean of 3 emotional scales of the Interpersonal Support Evaluation List) at study entry predicted changes 15-18 months later in a cardiovascular composite (linear combination of high-density lipoproteins-mean arterial pressure; p < .05), and natural killer cell activity (p < .05). For both outcomes, emotional supports were salutogenic for persons with lower incomes (< or =$29,000/year), but not for persons with higher incomes (>$29,000/year). In contrast, interactions of the Tangible Support Scale with income did not occur. Persons with lower incomes may derive benefits from social supports that go beyond tangible assistance.

Characteristics of socially isolated patients with coronary artery disease who are at elevated risk for mortality.

OBJECTIVES: Social isolation has been linked to poor survival in patients with coronary artery disease (CAD). Few studies have closely examined the psychosocial characteristics of CAD patients who lack social contact. METHODS: Social isolation was examined as a predictor of mortality in 430 patients with significant CAD. More isolated patients were compared with their less isolated counterparts on factors that might help explain the association between isolation and survival. RESULTS: The mortality rate was higher among isolated individuals. Those with three or fewer people in their social support network had a relative risk of 2.43 (p = .001) for cardiac mortality and 2.11 (p = .001) for all-cause mortality, controlling for age and disease severity. Adjustments for income, hostility, and smoking status did not alter the risk due to social isolation. With the exception of lower income, higher hostility ratings, and higher smoking rates, isolated patients did not differ from nonisolated patients on demographic indicators, disease severity, physical functioning, or psychological distress. Isolated patients reported less social support and were less pleased with the way they got along with network members, but they did not report less satisfaction with the amount of social contact received. CONCLUSIONS: Patients with small social networks had an elevated risk of mortality, but this greater risk was not attributable to confounding with disease severity, demographics, or psychological distress. These findings have implications for mechanisms linking social isolation to mortality and for the application of psychosocial interventions.

Central nervous system serotonin function and cardiovascular responses to stress.

OBJECTIVE: The objective of this study was to evaluate the impact of indices of central nervous system (CNS) serotonin function on cardiovascular reactivity to mental stress. METHODS: Lumbar puncture was performed on 54 healthy volunteers to obtain cerebrospinal fluid (CSF) for determination of 5-hydroxyindoleacetic acid (5HIAA) levels. Genotypes were determined with respect to a functional polymorphism of the serotonin transporter gene promoter region (5HTTLPR). Subjects then underwent mental stress testing. RESULTS: Persons with one or two long (l) 5HTTLPR alleles had CSF levels of the major serotonin metabolite, 5HIAA, that were 50% higher than those of persons with the s/s 5HTTLPR genotype. Persons with one or two l alleles or higher CSF 5HIAA levels also exhibited greater blood pressure and heart rate responses to a mental stress protocol. CONCLUSIONS: These findings suggest the 5HTTLPR polymorphism affects CNS serotonin function, and they are consistent with the general hypothesis that CNS serotonin function is involved in the regulation of potentially health-damaging biobehavioral characteristics. In particular, the l allele could contribute, through its association with increased cardiovascular reactivity to stress, to increased risk of cardiovascular disease.

Personality and coping with a common stressor: cardiac catheterization.

The association between coping and personality was examined in a sample of 204 cardiac catheterization patients who were asked to evaluate the use of specific coping strategies used to deal with their cardiac catheterization. Personality, as measured by the NEO Five-Factor Inventory (FFI), was moderately correlated with coping measures. In multivariate analyses, after considering confounding factors, Neuroticism was positively and Extraversion was negatively related to avoidance coping and Neuroticism was negatively associated with counting one's blessings as a coping strategy. Personality was not related to either problem solving or seeking social support coping strategies for individuals experiencing a cardiac catheterization. However, important covariates were associated with coping strategies. Not being married was negatively correlated with use of seeking social support and not having a confidant was negatively related with seeking social support and positively with avoidance. These results suggest that there are specific relationships between personality and coping, but these relationships are, for the most part, moderate in persons coping with a cardiac catheterization, and that coping processes are associated with individual differences in available social resources.