Harriet G. Williams

Motor Skill Performance and Physical Activity in Preschool Children

Children with better‐developed motor skills may find it easier to be active and engage in more physical activity (PA) than those with less‐developed motor skills. The purpose of this study was to examine the relationship between motor skill performance and PA in preschool children. Participants were 80 three‐ and 118 four‐year‐old children. The Childrens Activity and Movement in Preschool Study (CHAMPS) Motor Skill Protocol was used to assess process characteristics of six locomotor and six object control skills; scores were categorized as locomotor, object control, and total. The actigraph accelerometer was used to measure PA; data were expressed as percent of time spent in sedentary, light, moderate‐to‐vigorous PA (MVPA), and vigorous PA (VPA). Children in the highest tertile for total score spent significantly more time in MVPA (13.4% vs. 12.8% vs. 11.4%) and VPA (5% vs. 4.6% vs. 3.8%) than children in middle and lowest tertiles. Children in the highest tertile of locomotor scores spent significantly less time in sedentary activity than children in other tertiles and significantly more time in MVPA (13.4% vs. 11.6%) and VPA (4.9% vs. 3.8%) than children in the lowest tertile. There were no differences among tertiles for object control scores. Children with poorer motor skill performance were less active than children with better‐developed motor skills. This relationship between motor skill performance and PA could be important to the health of children, particularly in obesity prevention. Clinicians should work with parents to monitor motor skills and to encourage children to engage in activities that promote motor skill performance.

Carbohydrates and Physical/Mental Performance during Intermittent Exercise to Fatigue.

PURPOSE This study was designed to examine the effects of carbohydrate-electrolyte ingestion on physical and mental function associated with the performance of intermittent high-intensity (IHI) exercise similar to many common competitive sporting events. METHODS Physically active men (N = 5) and women (N = 5), experienced in competitive soccer or basketball, completed three practice sessions and two experimental trials of an IHI shuttle running protocol designed to closely stimulate the demands of an actual competitive sporting event such as basketball. The experimental trials consisted of four 15-min quarters (QTR) of intermittent shuttle running at various percentages of .VO(2max) (walking, jogging, running, sprinting and jumping), separated by a 20-min halftime rest period (HALF) and followed by a shuttle run to fatigue. Various tests of physical and mental function (shuttle run to fatigue, 20-m maximal sprint, 10-repetition maximal vertical jumping, whole body motor skill test (MS-Test), profile of mood states (POMS), and Stroop Color-Word Test) were performed throughout the experimental trial. Carbohydrate-electrolyte (CHO) or placebo (P) drinks were consumed before exercise (5 mL.kg(-1); 6% solution) and at halftime (5 mL.kg(-1); 18% solution). Smaller volumes (3 mL.kg(-1); 6% solution) were given after QTR-1, HALF, QTR-3, and QTR-4. RESULTS CHO ingestion resulted in a 37% longer run time to fatigue and faster 20-m sprint time during QTR-4 (P < 0.05). MS-Test performance was also improved during the latter stages of exercise along with self-reported perceptions of fatigue (subscale of POMS) (P < 0.05) in CHO versus P. CONCLUSION These results suggest a beneficial role of carbohydrate-electrolyte ingestion on physical and mental function during intermittent exercise similar to that of many competitive team sports.

Timing and motor control in clumsy children.

The study examined timing control in clumsy children and employed the Wing-Kristofferson (1973) model of repetitive movements in an attempt to identify the locus of timing control difficulties in clumsy children. Two groups of children classified as normal and clumsy (ages 6-7 and 9-10) performed tapping and perception of duration and loudness tasks. Results indicated that clumsy children were significantly more variable than normal children in maintaining a set rate of tapping and in accurately judging time intervals. Evidence indicated that the source of timing control problems in clumsy children may be in a central timekeeping mechanism, possibly the cerebellum.

Spectral characteristics of aging postural control

Abstract The purpose of this study was to apply techniques of spectral analysis to the study of postural control and determine if aging results in changes to spectral parameters obtained from postural forces. Subjects were young adults and elderly who live independently and had no difficulty performing tasks of daily living. Ground reaction forces were obtained from a measurement plat-form during repeated trials of static standing. Forces were analyzed using spectral analysis and selected parameters (central tendency and dispersion) were extracted from averaged spectral data. Significant differences were observed between age groups in all parameters extracted from spectra obtained from medial-lateral postural forces. Similar results were not obtained for data in the anterior-posterior direction. Results suggest that aging affects the spectral characteristics of postural forces used to maintain stability in the m-l direction.

Aging and Coordination from the Dynamic Pattern Perspective

Abstract Movement scientists have extensively described aging effects on speeded unilateral and uniarticular movements; in contrast, little is known about how aging affects the coordination of multi-degree of freedom actions. In this chapter we review studies on motor coordination (defined in terms of the spatio-temporal patterning among multiple elements of motor systems) in older adults. In addition, we present our application of the principles and research strategy of ‘dynamic pattern theory’ (Kelso & Schoner, 1988) to the study of aging and coordination. Findings on the older mover’s ability to coordinate intra- and inter-limb movements are equivocal. Older subjects exhibit (a) loose spatio-temporal coupling of muscle synergies during postural responses and (b) temporal asynchrony in discrete bimanual reaching. However, locomotor coordination (based on temporal relative phasing between the legs) appears to be well-maintained with age. We observed similar bimanual phasing relationships in 23-78 year olds during cyclical in-phase (IP) and anti-phase (AP) movements. In a phase shift experiment, where movement frequency was systematically increased, older subjects exhibited abrupt transitions from AP to IP cycling at significantly lower frequencies than young counterparts. We present findings which suggest that older subjects experience critical fluctuation and phase shifts at lower frequencies than young subjects due to fundamental deficiencies in coordination. We also present evidence for a deficiency in the speed at which older subjects execute voluntary changes from IP to AP movements. An explanation for age-related incoordination may be the relative strengthening of intrinsic dynamics. We discuss our findings in relation to conceptualizations of aging as a thermodynamic process whereby constraints are altered in ways that reduce behavioral stability and the ability to adapt to environmental challenges (Yates, 1988).

Effects of Feldenkrais Exercises on Balance, Mobility, Balance Confidence, and Gait Performance in Community-Dwelling Adults Age 65 and Older

BACKGROUND Falls and fall-related injuries are a major public health concern, a financial challenge for health care providers, and critical issues for older adults. Poor balance and limited mobility are major risk factors for falls. OBJECTIVE The purpose of this study was to examine effects of Feldenkrais exercises in improving balance, mobility, and balance confidence in older adults. METHODS Participants (N = 47, mean age 75.6) were randomly assigned to a Feldenkrais group (FG, n = 25) or to a control group (CG, n = 22). The FG group attended a 5-week Feldenkrais program, 60 minutes three times per week, while the CG group was a waitlist control. The outcome measures were balance (tandem stance), mobility (Timed Up and Go), gait characteristics (GAITRite Walkway System), balance confidence (Balance Confidence Scale; ABC), and fear of falling (Falls Efficacy Scale). Pre- and post-tests were conducted. RESULTS After completion of the program, balance (p = 0.030) and mobility (p = 0.042) increased while fear of falling (p = 0.042) decreased significantly for the FG group. No other significant changes were observed. However, participants of the FG group showed improvements in balance confidence (p = 0.054) and mobility while performing concurrently a cognitive task (p = 0.067). CONCLUSIONS These results indicate that Feldenkrais exercises are an effective way to improve balance and mobility, and thus offer an alternative method to help offset age-related declines in mobility and reduce the risk of falling among community-dwelling older adults. A long-term follow-up study of balance and mobility is warranted. Further research is needed to identify whether Feldenkrais exercises may impact cognitive processes.

DEVELOPMENT OF BILATERAL MOTOR CONTROL IN CHILDREN WITH DEVELOPMENTAL COORDINATION DISORDERS

This research examined behavioral (i.e. movement time) and neuromuscular (EMG) characteristics of unilateral and bilateral aiming movements of children with normal motor development and children with developmental coordination disorders (DCD). Two age groups of children were studied: 6 to 7, and 9 to 10 year olds. Bilateral aiming movements involved moving the two hands to targets of either (1) the same amplitude ‐ symmetrical bilateral movements, or (2) different amplitudes ‐ asymmetrical bilateral movements. Unilateral aiming movements involved moving one hand to either near or far targets associated with that hand. In general, unilateral and bilateral movement times were slower in younger than older children, and in children with DCD than children with normal motor development. Our neuromuscular data suggest that the faster movement times that typically accompany increasing age in children may be the result of a change in the capacity to initiate antagonist muscle contractions. The prolonged burst of agonist activity and delayed onset of antagonist activity observed in children with DCD may contribute to their inability to produce fast, accurate unilateral movements. On both symmetrical and asymmetrical bilateral aiming movements, children with DCD had more performance errors and greater temporal inconsistencies between neuromuscular (EMG) parameters and behavioral (movement time) parameters than children with normal motor development. These new neuromuscular data suggest that there are important differences in the way the motor control systems of children with and without DCD organize bilateral aiming responses.

Age-Related Differences in Timing Control of Repetitive Movement: Application of the Wing-Kristofferson Model

Age differences in timing control were investigated in persons between 6 and 75 years. Subjects performed a repetitive finger-tapping task, attempting to match a 550-ms interresponse interval (IRI). Response variability was analyzed using the method of Wing-Kristofferson (1973). An autocovariance technique estimated the proportion of the overall (total) IRI variability contributed by central (clock) and peripheral implementation (motor delay) processes. Significant age and gender differences were revealed only for total and clock variability. Results indicated that (a) young children (6-7 years) had higher variances than all other age groups, (b) older children (9-10 years) were more variable than young and middle-age adults, (c) variances did not differ significantly across three adult age groups (21-75 years), and (d) males were less variable than females for all age groups. In agreement with recent investigations that have used the Wing-Kristofferson methodology, this study suggests that age-related differences in timing control are largely a function of central processes.

Spectral characteristics of ageing postural control

Abstract The purpose of this study was to apply techniques of spectral analysis to the study of postural control and determine if ageing results in changes to spectral parameters obtained from postural forces. Subjects were young adults and elderly who live independently and had no difficulty performing tasks of daily living. Ground reaction forces were obtained from a measurement platform during repeated trials of static standing. Forces were analysed using spectral analysis and selected parameters (central tendency and dispersion) were extracted from averaged spectral data. Significant differences were observed between age groups in all parameters extracted from spectra obtained from medial-lateral postural forces. Similar results were not obtained for data in the anterior-posterior direction. Results suggest that ageing affects the spectral characteristics of postural forces used to maintain stability in the m-I direction.

Use of a questionnaire to screen for frailty in the elderly: An exploratory study

Background and aims: In a pilot study of community-dwelling geriatric clinic patients (N=48, aged 63–90) we examined the use of a questionnaire to classify frailty status by comparing it with standardized markers of frailty. The questionnaire, developed by Strawbridge et al. in 1998, defines frailty as difficulty in more than one of four domains of functioning: physical, cognitive, sensory, and nutritive. Methods: Subjects were classified as frail or not frail by questionnaire and assignment was compared with testing of physical and cognitive measures in cross-sectional analysis. Demographic variables, functional inventories, physical activity levels, clinician impression of frailty, and 3-year health outcomes were also examined. Results: Thirty-three percent of subjects were classified as frail. Frailty classification by the Strawbridge questionnaire was correlated to Timed Up and Go and repetitive Sit-to-Stand tests, bimanual dexterity and cognitive tests. A discrepancy was found between assignment of cognitive difficulty, by questionnaire and cognitive performance. When overall Strawbridge frailty scores were modified to account for those with poor cognitive performance who did not report cognitive difficulty, the prevalence of frailty increased to 42%. At 3-year follow-up, the modified Strawbridge frailty classification (p<0.05) and clinician impression of frailty (p<0.01) were both significant predictors of death and institution-alization combined. Conclusions: This study serves as an initial inquiry into the potential validity and utility of the Strawbridge frailty questionnaire as a simple screening tool to identify patients who may warrant detailed functional testing.