Exposure to repetitive tasks induces motor changes related to skill acquisition and inflammation in rats

The authors elucidate exposure-response relationships between repetitive tasks, inflammation, and motor changes with work-related musculoskeletal disorders. Using a rat model of reaching and handle pulling, they examined effects of performing a high-repetition, low-force (HRLF); low-repetition, high-force (LRHF); or high-repetition, high-force (HRHF) task (2 hr/day, 3 days/week, 12 weeks) on reach rate and force, percentage of successful reaches, duration of participation, and grip strength. Reach rate and reach force improved with HRLF, and percentage success increased in all groups in Week 9, and in HRLF and HRHF in Week 12, indicative of skill acquisition. Duration and grip strength showed force-dependent declines with task performance. A subset of HRHF rats received ibuprofen in Weeks 5-12. Ibuprofen significantly improved reach rate, reach force, and duration in treated rats, indicative of an inflammatory influence on reach performance. Ibuprofen improved percentage of successful reaches in Week 9, although this increase was not sustained. However, declines in grip strength, a nocifensive behavior, were not prevented by ibuprofen. Examination of cervical spinal cords of untreated and ibuprofen treated HRHF rats showed increased IL-1beta, an inflammatory cytokine, in neurons. These findings suggest that only a preventive intervention could have addressed all motor declines.     

Evaluation of physical activity measured via accelerometry in rural fourth-grade children

Interest in the benefits of exercise has prompted increased research examining the relationship between physical activity and health status in adults. More recently, considerable research effort has been directed toward the role of physical activity in young children as a precursor to adult physical fitness. The purpose of this study was to estimate the relationship between physical activity measured via accelerometry and body mass index, body mass, body composition, and physical fitness in fourth-grade boys and girls during physical education lessons. 54 fourth-grade students in rural Pennsylvania (28 girls, M age 9.6, SD = .56; 26 boys, M age 9.5, SD = .51) were subjects. Girls were significantly less active during all lessons measured (p < .001). The results of linear regression analyses indicated that physical activity was negatively associated with body mass index, body mass, and body fat percentage (p < .05), and positively associated with physical fitness (VO2max) (p < .01). These data indicate the need for curricular intervention to motivate girls to increase their activity during structured physical education lessons and demonstrate the efficacy of the body mass index as a screening tool within the schools.     

Exposure to Repetitive Tasks Induces Motor Changes Related to Skill Acquisition and Inflammation in Rats

The authors elucidate exposure-response relationships between repetitive tasks, inflammation, and motor changes with work-related musculoskeletal disorders. Using a rat model of reaching and handle pulling, they examined effects of performing a high-repetition, low-force (HRLF); low-repetition, high-force (LRHF); or high-repetition, high-force (HRHF) task (2 hr/day, 3 days/week, 12 weeks) on reach rate and force, percentage of successful reaches, duration of participation, and grip strength. Reach rate and reach force improved with HRLF, and percentage success increased in all groups in Week 9, and in HRLF and HRHF in Week 12, indicative of skill acquisition. Duration and grip strength showed force-dependent declines with task performance. A subset of HRHF rats received ibuprofen in Weeks 5–12. Ibuprofen significantly improved reach rate, reach force, and duration in treated rats, indicative of an inflammatory influence on reach performance. Ibuprofen improved percentage of successful reaches in Week 9, although this increase was not sustained. However, declines in grip strength, a nocifensive behavior, were not prevented by ibuprofen. Examination of cervical spinal cords of untreated and ibuprofen treated HRHF rats showed increased IL-1beta, an inflammatory cytokine, in neurons. These findings suggest that only a preventive intervention could have addressed all motor declines.     

References for motor tasks--gender differences across age in motor performance: a meta-analysis

In 1985 we published a meta-analysis of gender differences across age in motor performance in Psychological Bulletin, but it did not include an indexing of each motor task to the references from which it was obtained. This paper provides a table listing the 20 motor tasks and the references from which data for each task were taken. The range of tasks was from fundamental movements (e.g., catching, jumping, running, throwing) to motor fitness (e.g., agility, arm hang, balance, grip strength) to perceptual-motor abilities (e.g., anticipation timing, fine eye-motor coordination, pursuit-rotor tracking, reaction time). The arm hang was represented in the fewest papers (n = 2) while the dash and long jump were most frequently referenced (n = 21).     

Physical fitness and health indices in children, adolescents and adults with high or low motor competence

The overall purpose of the study was to examine if individuals with low motor competence achieve age-adequate fitness and health. A group of 149 children, adolescents, and adults with low or high motor competence participated in motor, fitness, and health assessments. Individuals with low motor competence did not differ on their basic physiological health parameters, but they had less optimal levels of overall health and fitness indices than those with high motor competence. As a function of age, musculoskeletal fitness was significantly compromised for the low motor competence group. The metabolic indices suggested that the low motor competence group had significantly higher BMI's compared to the high motor competence group. Motor skills and static balance were significant predictors of the BMI. Exercise intensity differed between children in the low and high motor competence group. The findings suggest that individuals with low motor competence have compromised health-related fitness. In order to discriminate between individuals with high and low motor competence, fitness assessment should include at least back extension, curl ups, and sit and reach. In addition, health-related fitness measurements such as BMI, waist circumference, blood lipid profile and bone mineral density are also recommended.     

Perceived Fitness and Responses to Laboratory Induced Stress

This study sought to evaluate the contribution of perceived physical fitness beyond the contributions of gender, body mass index (BMI), and estimated actual physical fitness on both physiological and self-reported stress responsivity to laboratory induced stress. Seventy-two nonsymptomatic participants participated in the experiment. Participants completed a laboratory procedure measuring cardiovascular responses and self-reported rating of calmness while performing stressful laboratory tasks. Estimated aerobic fitness (VO_{2 max}) as well as perceived fitness were also determined. Perceived fitness significantly contributed to the variance associated with self-reported responses to laboratory stress as well as with some of the physiological measures. Perceived fitness significantly added to the variance beyond that attributed to gender, body mass, and estimated actual physical fitness while assessing systolic blood pressure and calmness. Overall, the results support the view that perception of fitness may be an important factor above and beyond aerobic fitness in its association with responses to stress.     

EFFECTS OF ACHIEVEMENT MOTIVES AND SEX ON WRESTLING ABILITY AND MOTOR PERFORMANCE

An earlier study of main effects of achievement motives on performance amongst boy wrestlers was repeated with girls. The 1970 Achievement Motives Scale of Gjesme and Nygård was administered to 29 girls, and subjects' scores were sampled for three different wrestling championships at a national level. Oxygen uptake, speed of movement, four muscular strength exercises, and serial performance of five wrestling holds were measured. As with males, success-oriented females performed better than indifferent-oriented subjects in wrestling championships. The former group performed also better than the latter in pull-ups, sit-ups, forward throw and 1/4 Nelson. In addition, success-oriented females performed better than those who were failure-oriented in pull-ups and sit-ups, although this was not the case in other tasks and championships. Indications of sex differences in the relationship between motivation and performance were found among subjects who aim for achievement and, at the same time, have a high motive for failure, i.e. those who were conflict-oriented. Motive patterns and sex influence some, but not all, of the responses measured in the different tasks. Suggestions for future systematic research on a task effect are discussed. In general, the data indicate that, among highly selected and high ability boys and girls who set a high value on goals of an activity, relationships between achievement motives and performance in that activity should emerge for both sexes. In addition, sex should modify motive-performance relationships.     

The influence of motor function on processing speed in preterm and term-born children

This study investigates the relationship between motor function and processing speed in preterm children. Processing speed was compared in 145 adolescents, born 25–41 weeks gestational age, utilizing tasks including differing motor demands. The influence of motor cortex excitability and functional motor skills on task performance was assessed. For tasks with motoric demands, differences in performance between preterm and term-born children were mediated by the relationship between gestational age, corticomotor excitability, and motor function. There were no differences in non-motor processing speed task performance between preterm and term-born children. Measures of processing speed may be confounded by a timed motor component.     

Physical fitness and self-reported physical exercise among college men and women in 1987 and 1997.

The study examined the relations of self-reported physical activity levels and physical fitness scores for two samples of college students assessed in 1987 (n = 261) and in 1997 (n = 243). Significantly greater exercise was reported by the 1997 women than the 1987 women; amount of exercise reported by men did not differ. For both samples, greater exercise was associated with increased fitness for women and men as assessed by the Hall 1986 Physical Fitness Test Profile, comprised of measures on body fat composition; grip strength; muscle endurance, flexibility, resting heart rate; systolic and diastolic blood pressures; and aerobic power. For the 1987 sample men were more fit than women. For the 1997 sample, women were more fit than men. The 1997 women were more fit than the 1987 women; there was no difference on overall fitness measures of the two samples of men.     

Effects of aerobic exercise training, age, and physical fitness on memory-search performance

We investigated the effects of exercise training on memory performance. One group of 13 men (M = 42.92 years of age) participated in supervised aerobic exercise (jogging) three times a week for 12 weeks. A second group of 15 men (M = 43.67 years of age) performed anaerobic exercise (strength training) for the same period of time. Subjects' reaction time (RT) performance in a memory-search task was assessed both before (Time 1) and after (Time 2) the 12 weeks of exercise training. Results indicated that there was no significant change in memory-search performance over time as a function of exercise training. Analyses of the Time 2 RTs demonstrated that aspects of memory-search performance were related significantly both to subjects' initial (Time 1) level of fitness and to age, but not to the amount of change in fitness associated with aerobic exercise training over this 12-week duration in this age group.     

Longitudinal development of manual motor ability in autism spectrum disorder from childhood to mid‐adulthood relates to adaptive daily living skills

Many individuals with autism spectrum disorder (ASD) exhibit motor difficulties, but it is unknown whether manual motor skills improve, plateau, or decline in ASD in the transition from childhood into adulthood. Atypical development of manual motor skills could impact the ability to learn and perform daily activities across the life span. This study examined longitudinal grip strength and finger tapping development in individuals with ASD (n = 90) compared to individuals with typical development (n = 56), ages 5 to 40 years old. We further examined manual motor performance as a possible correlate of current and future daily living skills. The group with ASD demonstrated atypical motor development, characterized by similar performance during childhood but increasingly poorer performance from adolescence into adulthood. Grip strength was correlated with current adaptive daily living skills, and Time 1 grip strength predicted daily living skills eight years into the future. These results suggest that individuals with ASD may experience increasingly more pronounced motor difficulties from adolescence into adulthood and that manual motor performance in ASD is related to adaptive daily living skills.     

Sex Referent Cues,Success Estimations,and Performance of Children on a Lateral Jumping Task

This study examined the effects of sex referent cues for the estimation of success, as well as actual performance on a simple motor endurance task. Boys and girls in grades 3 and 5 (N = 160) were randomly assigned to one of three referent groups or a control group. Subjects in the referent groups were given an identical referent score, (48), presented in three different forms: the average score for boys, the average score for girls, and the average score for children. The control group was given no referent score. Subjects were required to estimate their own success and then perform a timed side-to-side jump over a rope. Results suggest that as girls increase in age there is a decrease in their confidence in performing motor skills. Further, boys and girls at the two grade levels responded differently to the sex referent cues.     

Accuracy of two simple methods for the assessment of health-related physical fitness

We have developed a useful equation for estimating health-related physical fitness age. This version of health-related fitness age was developed as an extension of the biological age index and is useful for evaluation of individual differences in functional abilities of middle-aged and older adults. This measure consists of 4 independent variables fitness (VO2 max, standing trunk flexibility, %fat, and grip strength). However, direct measurement of maximal oxygen uptake (VO2 max) is an invasive clinical procedure and not practical for large scale work. In the current study, we attempted to assess the fitness age more feasibly. We selected a questionnaire method and a 12-min. submaximal treadmill walk test as substitutes for the VO2 max test. The three fitness ages were computed for 23 Japanese men (M(age) 54.7 +/- 10.7 yr.), using actual VO2 max (actual fitness age), questionnaire VO2 max (predicted questionnaire fitness age), and treadmill VO2 max (predicted treadmill fitness age). Predicted questionnaire fitness age (61.0 +/- 10.5 yr.) and predicted treadmill fitness age (60.0 +/- 12.4 yr.) were significantly correlated with actual fitness age (60.1 +/- 12.4 yr.) (r= .96 and .97, respectively). There were no significant differences among the three indices, but there was a significant difference between actual fitness age and chronological age (p<.05). For VO+/-2 max substituting the questionnaire for the treadmill estimate is acceptable in assessing fitness age and reducing the clinical risk for middle-aged and older Japanese men.     

Association Between Body Mass Index and Motor Competence in Santal Children of Purulia District,India

The purpose of this study was to evaluate the relationship between body mass index and motor competence in Santal children 5–12 years old. A total of 816 Santal children were studied. Children's adiposity status was assessed by body mass index (BMI) for age z-score based on World Health Organization reference data. Motor competence was measured using the Bruininks-Oseretsky Test of Motor Competence (BOT-2). There was no significant difference in mean BMI z-score between Santal boys (0.13 ± 0.07) and girls (?0.14 ± 0.07). Healthy weight (HW) children scored higher (p < .05) in some individual motor subtests (bilateral competence, balance, running speed and agility, upper limb competence, and strength) and in total BOT-2 score (p < .05) compared with scores for underweight (UW) and overweight (OW) children. Nonlinear regression analysis showed that BMI is a significant independent predictor of motor competence (p < .01). Motor competence showed a curvilinear relationship with BMI-z-score, with the lowest point motor scores in strength and upper limb competence (p < .05) for both UW and OW children compared to HW children who scored highest. The results also indicated that gross motor skills, but not fine motor skills, were poorer among children who were UW or OW compared with HW children.     

Physical Fitness as a moderator of cognitive work capacity and fatigue onset under sustained combat-like operations

A study was devised to investigate the role of physical fitness in moderating both cognitive work capacity and fatigue onset under sustained combat operations. Sixteen male ROTC cadets were followed through a 2.5-day, Pre Ranger Evaluation exercise. Prior to the start of the exercise, the cadets’ overall level of physical fitness was assessed by using five fitness indices (Harvard Step Test, chin-ups, push-ups, sit-ups, and two-mile run). Cognitive performance and subjective measures of fatigue state were assessed at regular intervals before, during, and 1 day after the exercise. The results suggest that fitness may attenuate decrements in cognitive work capacity for certain tasks requiring prolonged mental effort, particularly as the cumulative effects of sleep loss and other stressors begin to mount. Similarly, the results suggest that as overall stress levels increase, fitness may have a beneficial effect in moderating fatigue rate. Fitness did not significantly enhance the recovery process with respect to cognitive work capacity, and actually appeared to hinder recovery from fatigue.     

Self-perception of health and fitness among French and Tunisian men and women

This work examines the effects of sex and culture on physical self-perceptions. The aim was to compare the perception of physical fitness of French and Tunisian men and women. 400 individuals ages 20 to 35 years assessed their own fitness, endurance, strength, flexibility, body composition, and health according to specific category scales by completing a questionnaire. In general, the Tunisian group rated themselves higher than the French group. It appears that perceived physical fitness was related mainly to perceived endurance for both groups. Some disparities were observed between the two nationalities. Analysis showed an interaction between sex and culture (French vs Tunisian). For French men and women and Tunisian men, perceived physical fitness was more associated with perceived endurance, whereas for Tunisian women, perceived physical fitness was more strongly associated with flexibility. These data show that self-perception of physical fitness is a dimension which varies between individuals from different cultures.     

Objective aerobic fitness level and neuropsychological functioning in healthy adolescents and emerging adults: Unique sex effects

ObjectiveResearch suggests positive relationships between aerobic fitness and cognition in older adults; however, limited research has adequately investigated the relationship between objectively measured aerobic fitness and broad cognitive functioning in healthy adolescents and young adults without psychiatric or physical health disorders. Further, studies to date have disproportionately examined males and failed to examine sex differences. Here we examine the relationship between aerobic fitness and neuropsychological functioning in physically healthy youth and whether sex moderates these findings.DesignSixty-four healthy emerging adults (16-25 years-old; 32 female) underwent measurement of objective aerobic fitness (VO₂ max) and neuropsychological assessment. Exclusion criteria included: left-handedness, prenatal medical issues or alcohol/illicit drug exposure, Axis-I psychiatric disorders, major medical disorders including metabolic conditions such as diabetes, hypertension, hyperlipidemia, major neurologic disorders, LOS greater than 2 min, intellectual disability or learning disability, regular substance use (e.g., greater than bi-weekly use of cannabis) or positive drug toxicology testing.MethodMultiple regressions examined VO₂ max, sex, sex*VO₂interaction in relation to neurocognition, controlling for objectively measured body fat percentage.ResultsPrior to including body fat percentage, higher VO₂ max related to improved working memory (Letter-Number Sequencing; p = .03) and selective attention (CPT-II hit response time standard error; p = .03). Aerobic fitness significantly interacted with sex, as higher-fit males had better performance on two sustained attention tasks while females did not demonstrate this pattern (CPT-II variability standard error, p = .047; Ruff 2&7 Total Speed, p = .02). Body fat percentage was positively slower cognitive flexibility (D-KEFS color-word switching/inhibition, p = .046).ConclusionsVO₂ independently predicted better working memory and selective attention. Increased aerobic fitness level related to increased performance on sustained attention tasks in males but not females. Therefore, aerobic fitness may be positively related to better cognitive functioning in physically healthy adolescents and emerging adults without metabolic conditions. Further research into factors (e.g., intensity or type of activity) that may relate to beneficial outcomes by sex are needed.     

Grip strength impairments among older adults receiving physical therapy in a home-care setting

A hand-grip dynamometer was used to assess the magnitude and prevalence of grip strength impairments among 41 home-care patients with diverse diagnoses (e.g., stroke, cancer, fracture, osteoarthritis). Based on published reference values, patients (as a whole) were weaker than normal for age and sex. The prevalence of weakness was 85.4% on one or the other side and 70.7% on both sides. Considering the prognostic importance of grip strength, this study emphasized the potential value of its measurement in a home-care population.     

Physical performance in relation to age, sex, birth order, social class, and sports activities of preschool children

Physical performance of 1,194 preschool children, ages 43 to 84 mo. was related to characteristics of physical growth, cognitive performance, and social variables. Correlations between measures of physical growth and physical performance and between motor and cognitive performance were positive and significant. Physical fitness, body coordination, and manual dexterity improved across age groups. Significant sex differences were found, although boys exceeded on some measures and girls on others. Children with older sisters or brothers performed better than only or first-born children, and children who participated in sports activities outside school outperformed those who did not.     

Neuropsychological assessment in illiterates: visuospatial and memory abilities

A basic neuropsychological battery of visuospatial and memory abilities was administered to extreme educational groups (illiterates and professionals). Subjects were matched according to sex and age. The following visuospatial tasks were included: figure copy (cube, house, and Rey-Osterrieth complex figure), telling time, recognition of superimposed figures, recognition of a map, and drawing of the plan of the room. The following memory tasks were used: basic information, digit retention (forward and backward), memory curve, delayed verbal recall, sentence repetition, logical memory, delayed logical memory, immediate recall of the Rey-Osterrieth complex figure, immediate reproduction of a cube, visuospatial memory, and sequential memory. In visuospatial tasks all differences between the two groups were statistically significant. Five of the seven visuospatial tasks (all but telling time and recognition of superimposed figures) showed differences between age groups with a better performance found in the younger groups and four of the tasks (cube, house, Rey-Osterrith complex figure copying, and telling time) were significant between sexes with a better performance in men. In memory tasks, with the exception of the immediate memory of sentences, all tasks showed statistically significant differences between educational groups. Eight of the 13 memory tasks (digits forward and backward, delayed memory of words, immediate and delayed logical memory, Rey-Osterrieth immediate memory, cube immediate memory, and sequential memory) showed significant differences for age while 4 of the tasks (digits backward, memory curve, Rey-Osterrieth immediate memory, and cube immediate memory) were significant for sex. Results are analyzed with regard to current theories in cognitive psychology and anthropology. Emphasis is placed on the finding that cognitive skills usually examined by neuropsychological tests represent learned and highly trained abilities.