Coactivation of the knee extensors and flexors increases knee joint contact forces, which may lead to degradation of the articular surfaces. This study investigated the effect of neuromuscular fatigue induced by submaximal, repetitive, dynamic contractions on coactivation of knee musculature in young and middle-aged women. Data from 10 young women (24.6 ± 1.8 years) and 8 middle-aged women (55.4 ± 4.2 years) were analyzed. Measures included peak knee extension and flexion torques and the average amplitude of surface electromyography of rectus femoris and biceps femoris. Coactivation ratios were calculated from these activations. To induce fatigue, participants completed up to ten sets of 50 concentric knee extension and flexion contractions at 60°/s. A two-factor analysis of variance was used to determine the effect of age and fatigue. The young group showed higher peak torque compared with the middle-aged group (P < .001). During flexion, biceps femoris activity increased after fatigue when both groups were considered together (P = .018). During extension, biceps femoris activity was higher in the middle-aged than young group (P = .043). Middle-aged women exhibited a trend for greater coactivation during knee extension compared with young women (P = .066). This coactivation likely contributed to extension torque decrements in middle-aged women.
Joanne N. Hodder, Tova E. Plashkes, Regan A. Franklin, Heather K. Hickey and Monica R. Maly
Toby G. Pavey, Nicola W. Burton and Wendy J Brown
There is growing evidence that regular physical activity (PA) reduces the risk of poor mental health. Less research has focused on the relationship between PA and positive wellbeing. The study aims were to assess the prospective associations between PA and optimism, in both young and mid-aged women.
9688 young women (born 1973–1978) completed self-report surveys in 2000 (age 22 to 27), 2003, 2006, and 2009; and 11,226 mid-aged women (born 1946–1951) completed surveys in 2001 (age 50–55) 2004, 2007, and 2010, as part of the Australian Longitudinal Study on Women’s Health. Generalized estimating equation models (with 3-year time lag) were used to examine the relationship between PA and optimism in both cohorts.
In both cohorts, women reporting higher levels of PA had greater odds of reporting higher optimism over the 9-year period, (young, OR = 5.04, 95% CI: 3.85–6.59; mid-age, OR = 5.77, 95% CI: 4.76–7.00) than women who reported no PA. Odds were attenuated in adjusted models, with depression accounting for a large amount of this attenuation (young, OR = 2.00, 95% CI: 1.57–2.55; mid-age, OR = 1.64 95% CI: 1.38–1.94).
Physical activity can promote optimism in young and mid-aged women over time, even after accounting for the negative effects of other psychosocial indicators such as depression.
Marie-Jasmine Lalonde-Parsi and Anouk Lamontagne
Whether a reduced perception of self-motion contributes to poor walking speed adaptations in older adults is unknown. In this study, speed discrimination thresholds (perceptual task) and walking speed adaptations (walking task) were compared between young (19–27 years) and young-old individuals (63–74 years), and the relationship between the performance on the two tasks was examined. Participants were evaluated while viewing a virtual corridor in a helmet-mounted display. Speed discrimination thresholds were determined using a staircase procedure. Walking speed modulation was assessed on a self-paced treadmill while exposed to different self-motion speeds ranging from 0.25 to 2 times the participants’ comfortable speed. For each speed, participants were instructed to match the self-motion speed described by the moving corridor. On the walking task, participants displayed smaller walking speed errors at comfortable walking speeds compared with slower of faster speeds. The young-old adults presented larger speed discrimination thresholds (perceptual experiment) and larger walking speed errors (walking experiment) compared with young adults. Larger walking speed errors were associated with higher discrimination thresholds. The enhanced performance on the walking task at comfortable speed suggests that intersensory calibration processes are influenced by experience, hence optimized for frequently encountered conditions. The altered performance of the young-old adults on the perceptual and walking tasks, as well as the relationship observed between the two tasks, suggest that a poor perception of visual motion information may contribute to the poor walking speed adaptations that arise with aging.
Stephanie Truelove, Leigh M. Vanderloo and Patricia Tucker
Many young children are not meeting the Canadian physical activity guidelines. In an effort to change this, the term active play has been used to promote increased physical activity levels. Among young children, physical activity is typically achieved in the form of active play behavior. The current study aimed to review and synthesize the literature to identify key concepts used to define and describe active play among young children. A secondary objective was to explore the various methods adopted for measuring active play.
A systematic review was conducted by searching seven online databases for English-language, original research or reports, and were eligible for inclusion if they defined or measured active play among young children (ie, 2 to 6 years).
Nine studies provided a definition or description of active play, six measured active play, and 13 included both outcomes. While variability in active play definitions did exist, common themes included: increased energy exerted, rough and tumble, gross motor movement, unstructured, freely chosen, and fun. Alternatively, many researchers described active play as physical activity (n = 13) and the majority of studies used a questionnaire (n = 16) to assess active play among young children.
Much variability in the types of active play, methods of assessing active play, and locations where active play can transpire were noted in this review. As such, an accepted and consistent definition is necessary, which we provide herein.
Marianne Haguenauer, Pierre Legreneur and Karine M. Monteil
To our knowledge jumping kinematics have never been studied in elderly persons. This study was aimed at examining the influence of aging on vertical jump performance and on interjoint coordination. Two groups of adults, 11 young men ages 18–25 years and 11 older men ages 79–100 years, were filmed while performing a maximal squat jump. Compared to young adults, jump height was significantly decreased by 28 cm in the elderly. Older adults spontaneously jumped from a more extended position of the hip. Results showed a decrease in hip, knee, and ankle linear velocity and angular amplitude with aging. The decrease in jump height was attributed to a decrease in explosive force and in the range of shortening of extensor muscles. In agreement with the literature, a proximo-distal coordination pattern was observed in young adults. Older adults used a simultaneous pattern. This may indicate that adults adjust their pattern of joint coordination as they age.
Ang Chen and Weimo Zhu
A physically active or inactive lifestyle begins with intuitive interest at a very young age. This study examined the impact of selected personal, school, and home variables on young children’s intuitive interests in physical and sedentary activities.
National data from the Early Childhood Longitudinal Study (US Department of Education) were examined using Cohen’s d, hierarchical log-linear analyses, and logistic regression.
Children’s interest in physical activity is accounted for fractionally by personal variables, but substantially by school and home variables including number of physical education classes per week, teacher experiences of teaching PE, and neighborhood safety.
School and home environment variables have stronger impact than personal variables on children’s intuitive interest in physical activity. Future interventions should focus on strengthening school physical education and providing a safe home environment to help nurture young children’s intuitive interest in physical activity.
James Lyons, Digby Elliott, Laurie R. Swanson and Romeo Chua
This study was designed to examine the influence of age and the availability of vision on the performance and kinematic characteristics of discrete aiming movements. Twelve young adults (19–25 years old) and 12 healthy older adults (62–82 years old) performed 130-mm aiming movements to targets with diameters of 5, 10, and 20 mm. On half the trial blocks, visual feedback about the aiming movement was eliminated upon movement initiation. Surprisingly, older adults were both as fast and as accurate as young adults regardless of the vision or target condition. While the velocity profiles of young and older adults were also similar, older adults exhibited a greater number of deviations in acceleration in both the vision and no-vision situations. Since these deviations are thought to reflect adjustments to the movement trajectory, older adults may rely more on visual and kinesthetic feedback for the control of goal-directed movement.
Alon Eliakim, Mark Y. Moromisato, David Y. Moromisato and Dan M. Cooper
In this study, the hypothesis that improvements in functional and structural measures could be detected in the young, female rat with only 5 days of moderate treadmill training was tested. Eight-week-old female Sprague-Dawley rats were divided randomly into control (n = 10) and training groups (n = 11). Over the 5-day period, running duration and treadmill speed increased progressively. Maximal running time and gas exchange were measured on Day 6. In trained compared with control rats, maximal running time was 54% greater (p < .005), right hindlimb muscle was 16% heavier (p < .01), and end-exercise respiratory exchange ratio (RER) was 17% lower (p < .05). Substantial metabolic and structural adaptations occurred in young female rats after only 5 days of treadmill training. This protocol may be useful in discovering the initiating mechanisms of the training response in the young organism.
Kelly S. Chu, Edward C. Rhodes, Jack E. Taunton and Alan D. Martin
The purpose of this study was to assess the difference in maximal physiological responses between an acute bout of deep-water running (DWR) and treadmill running (TMR) in young and older adults. Participants were 9 young and 9 older women who performed maximal DWR and TMR tests. Maximal measures included oxygen consumption (VO2max), heart rate (HRmax), ventilation (VE), respiratory-exchange ratio (RER), and blood lactate (BLac). The young women exhibited higher VO2max, HRmax, VE, and BLac than did the older women for both exercise conditions (p < .05). Lower VO2max and HRmax values were observed with DWR for both age groups (p < .05). No significant differences were found for VE, RER, and BLac in either group between exercise conditions, nor a significant interaction between exercise conditions or ages for any of the variables measured. The data suggest that although older adults exhibit lower maximal metabolic responses, differences between DWR and TMR responses occur irrespective of age.
C.K. John Wang and Stuart J.H. Biddle
A great deal has been written about the motivation of young people in physical activity, and the determinants of activity for this age group have been identified as a research priority. Despite this, there are few large-scale studies identifying “types” or “clusters” of young people based on their scores on validated motivation inventories. This study reports the results of a cluster analysis of a large national sample (n = 2,510) of 12- to 15-year-olds using contemporary approaches to physical activity motivation: achievement goal orientations, self-determination theory (including amotivation), the nature of athletic ability beliefs, and perceived competence. Five meaningful clusters were identified reflecting two highly motivated and two less well-motivated clusters, as well as a clearly amotivated cluster. Groupings were validated by investigating differences in physical activity participation and perceptions of physical self-worth. Some clusters reflected age and gender differences. The results provide valuable information for likely strategies to promote physical activity in young people.