Comparison of the RT3 Research Tracker and Tritrac R3D accelerometers during a backpacking expedition by a single subject

This study compared the RT3 Research Tracker accelerometer and the Tritrac R3D accelerometer in a field setting. A six-day backpacking expedition (122.4 km in length) was completed by a single subject in the Grand Canyon National Park, Arizona. The overall correlation between the counts of vector magnitude activity for the RT3 and R3D was moderate (r =.75, p<.001), with the overall calculated bias [mean difference (RT3 minus R3D) and standard deviation of the differences] across all six days estimated at 235+/-436 vector magnitude activity counts. However, agreement between the instruments is problematic; the RT3 might be 201 activity counts below or 671 activity counts above the R3D in assessing physical activity during backpacking.     

The use of the large-scale integrated sensor (LSI) to estimate energy expenditure

The relationship between activity counts from the large-scale integrated sensor (LSI), placed at the hip and ankle, and heart rate-estimated energy expenditure was examined in three nonobese males during three conditions: normal morning activities, a 1-mi walk, and a 2-mi walk. Results showed that estimated caloric expenditure was related to activity counts for both monitoring placements, with correlations between counts and energy expenditure exceedingr=.90. These results show that energy expenditure in the activities sampled can be reliably estimated using activity monitors.This research was supported in part by a grant provided by The John D. and Catherine T. MacArthur Foundation Research Network on the Psychobiology of Depression, Clinical Research Center Grant 5-30915 from the NIMH, and Grant HD 16411 from the NICHD awarded to Dr. Epstein.     

Comparison of the RT3 Research Tracker and Tritrac R3D accelerometers

This study compared the RT3 Research Tracker accelerometer to the Tritrac R3D accelerometer in both laboratory and field settings and tested the hypothesis that the RT3 records higher physical activity counts and smaller standard deviations than the R3D. The RT3 is relatively new and untested and its concurrent validity with existing instruments and physical activity needs to be assessed before being used in research. In this study the RT3 had higher average recordings of physical activity counts in all of the nine testing situations than the R3D. However, in terms of agreement between the instruments, the RT3 might be 582 below or 1,236 above (activity counts) the R3D in assessing physical activity. These results do not establish that the RT3 is more consistently measuring higher physical activity counts than the R3D. Comparing vector magnitude with oxygen consumption and heart rate across the 0% grade testing conditions indicated that the RT3 and R3D are sensitive to changes in various intensities of level ambulation. When the 5%, 10%, and 15% grade on the treadmill protocols were analyzed, low correlations between oxygen consumption and heart rate with vector magnitude responses were found for both the RT3 and R3D. Differences in agreement between the RT3 and R3D did not vary in any systematic way over the range in testing conditions which substantiates that the RT3 and R3D accelerometers are sensitive on flat surfaces but are insensitive to changes in grade.     

No pain, no gain: Perceptions of calorie expenditures of exercise and daily activities

Reduction in physical activity is considered a major contributor to weight problems. Increasingly, people are expending less energy in household chores but joining fitness clubs. Do people perceive ordinary daily activities to expend less energy than exercise activities using similar amounts of calories? In the present study college students were asked to evaluate the calorie expenditure of 30 physical activities (i.e., exercises and household tasks). The household tasks were matched (in terms of caloric expenditure) to at least one exercise activity. When participants rated both exercise and daily activities, it appears that they focused on rate of caloric expenditure rather than type of activity (i.e., household task or exercise). In Study 2, college students evaluated the energy expenditure of light/leisure, moderate, and intense exercise. This emphasis concerning the benefit of intense physical activity was observed once again. College students appear to have assimilated the belief that intense physical activity expends more energy than longer sessions of lower intensity physical activity using similar amounts of calories. Perhaps one reason why people are not physically active is that they believe physical activities must be intense to be of benefit. At the same time they are automatizing household chores and, thus, become less active overall.     

No pain, no gain: Perceptions of calorie expenditures of exercise and daily activities

Reduction in physical activity is considered a major contributor to weight problems. Increasingly, people are expending less energy in household chores but joining fitness clubs. Do people perceive ordinary daily activities to expend less energy than exercise activities using similar amounts of calories? In the present study college students were asked to evaluate the calorie expenditure of 30 physical activities (i.e., exercises and household tasks). The household tasks were matched (in terms of caloric expenditure) to at least one exercise activity. When participants rated both exercise and daily activities, it appears that they focused on rate of caloric expenditure rather than type of activity (i.e., household task or exercise). In Study 2, college students evaluated the energy expenditure of light/leisure, moderate, and intense exercise. This emphasis concerning the benefit of intense physical activity was observed once again. College students appear to have assimilated the belief that intense physical activity expends more energy than longer sessions of lower intensity physical activity using similar amounts of calories. Perhaps one reason why people are not physically active is that they believe physical activities must be intense to be of benefit. At the same time they are automatizing household chores and, thus, become less active overall.     

Effects of a short-term exercise program on caloric consumption

The present study investigated the effects of a short-term exercise program on caloric intake. Thirty-three women were randomly assigned to either a high-intensity exercise group (80% maximum heart rate), low-intensity exercise group (55% maximum heart rate), or waiting list control group. Exercisers were required to ride ergometer bicycles three times per week for 7 weeks, expending 200 kilocalories of energy per exercise session. All participants recorded food intake during specified weeks before, during, and following the exercise program. Results showed no significant caloric intake differences among the three groups, but a trend toward reduction in food intake with increased exercise intensity was found. Interestingly, comparisons between caloric intake on exercise and nonexercise days revealed that both exercise groups consumed significantly less on exercise days. Additionally, the control group evidenced a larger caloric intake level than did the two exercise groups on exercise days. These results suggest that exercisers do not compensate for energy expenditure by increasing caloric intake and that choosing between low- and high-intensity exercise does not differentially alter caloric intake. Nevertheless, maximization of negative energy balance or weight loss may be best achieved by exercise programs of high frequency and intensity.     

Adolescents' energy cost in marching band

The primary purpose of this study was to examine adolescents' energy cost in a marching band. High school marching band participants (N=15) completed five 3-min. stages of treadmill marching, using a 57.2-cm stride length (typical standard of eight steps per five yards) as follows: without instruments at 75 m x min.(-1) and 132 steps x min.(-1) (Stage 1): without instruments at 91 m x min.(-1) and 160 steps x min.(-1) (Stage 2); carrying instruments at 75 m x min.(-1) and 132 steps x min.(-1) (Stage 3); carrying instruments at 91 m x min.(-1) and 160 steps x min.(-1) (Stage 4); and playing instruments at 75 m x min.(-1) and 132 steps x min.(-1) (Stage 5). Mean heart-rate response to an actual parade performance was similar to the mean Stage 5 treadmill heart rate (n=6). With regard to a high school marching band, these results suggest that energy demand for marching cadences approximates 4.5 and 6.0 metabolic equivalents for moderate and fast paces, respectively.     

Energetic and motor responses to increasing force requirements

The effects of increasing work (force) requirements on energy expenditure and response topography were examined in 7 rats pressing a beam to earn food. For the 1st 16 days, the force requirement was 5.52 x 10(-2) N (5.625 g). This increased by 4.91 x 10(-2) N (5 g) every 7th session until Ss had experienced 10 upward shifts. Following the 54.57 x 10(-2) N (55.625 g) condition, the original criterion was reinstated. During the augmented phase. Ss maintained stable reinforcement rates across conditions by increasing the peak force of beam pressing. These higher forces, occurring within 20 reinforcements of changing the force criterion, were produced primarily by increases in the rate of change of force (delta F/delta T). Also, while the rate of work performed on the beam increased, the overall energy expenditure fell. In contrast to these rapid adjustments, reinstating the original 5.52 x 10(-2) N (5.625 g) criterion resulted in only gradual alterations in motor performance.     

Lateral dominance of legs in maximal muscle power, muscular endurance, and grading ability.

The purpose of this study was to examine lateral dominance in maximal muscle power, muscular endurance, and grading ability, using isokinetic mulscular strength in knee extension and flexion. The subjects were 50 healthy male students whose ages ranged from 19 to 23 years (M height: 173.6+/-6.2 cm, M weight: 67.2+/-6.8 kg). Their dominant legs for power exertion and for functional use were based on questionnaire items selected from those used in previous studies. The angular velocities of extension and flexion for exerting maximal muscle power were 60, 180, and 300 x sec.(-1). A continuous exertion 30 times at an angular velocity of 180 sec.(-1) was used as the load for muscular endurance. For grading ability, 25%, 50% and 75% of the maximal muscle strength at angular velocities of 60 and 180 x sec.(-1) were the required values, and the difference between these values and the exerted muscular strength was evaluated. The dominant leg and nondominant leg were compared for both power exertion and functional use. There was no lateral dominance in maximal muscle power and muscular endurance. In muscular endurance, especially, some subjects showed one leg superior in power exertion and some superior in functional use. Lateral dominance was noted across maximal muscle power and muscular endurance in grading ability. The dominant leg tended to be better than the nondominant leg in functional use. However, lateral dominance was not remarkable for flexing motion and in exertion for a short time.     

Comparison of selected perceptual variables for backpacks with internal and external frames

Differences in perceptions of comfort, exertion, balance, and heart rate were investigated with two types of backpack. Subjects were 20 male volunteers (M age = 24.3 yr., SD: 3.6, M height = 180.02 cm, SD: 8.0, and M weight = 86.46 kg, SD: 14.84). Following oral briefing and practice trials, each subject was fitted at random with either an internal- or external-frame backpack containing 18.2 kg. By random, cross-over design, subjects completed a 30-m simulated hiking trial consisting of 16 separate obstacles designed to resemble actual off-trail hiking. Trials were conducted in a controlled environment with the walking intensity regulated by a metronome. Upon completion of each trial, the subjects rated the experience on perceived comfort, balance and stability, and rating of perceived exertion. Heart rate was recorded immediately prior to and following each trial. Analysis yielded a significant difference only on rating of perceived exertion in favor of the internal-frame backpack. Under limited circumstances, these data suggest that both types of backpacks provide similar comfort and balance and stability; however, internal frames in backpacks may reduce perceived exertion during short, demanding hikes.     

The effects of progressive relaxation on stress and diabetic control

Four insulin-requiring diabetic Ss were followed in single-S designs to measure the impact of progressive muscle relaxation training on blood glucose and stress levels. Measures of blood glucose, stress, activity and caloric intake were taken four times a day, along with a daily measure of anxiety. Two of the 4 Ss showed a significant decrease in blood glucose during treatment periods as compared to baseline measures. Similarly, 2 of the 4 Ss showed a significant decrease in stress levels during treatment. A multiple regression analysis revealed some significant relationships between blood glucose, stress, activity level and caloric intake. The results support previous studies that show relaxation techniques to be a viable aid in establishing greater diabetic control.     

Correlates of exercise adherence in an African American church community

This study identified correlates of attendance to a community-based exercise program in an African American church congregation. After medical clearance, 48 participants completed measures of social support, health-related quality of life, depression, exercise self-efficacy, and exercise motivation and then participated in an exercise program for 6 months (attendance rate = 27%). Age, a sense of affiliation as a motivator to exercise, and weekly caloric expenditure derived from yard work were positively associated with program attendance, and full- or part-time employment was negatively associated with attendance. The authors concluded that exercise adherence is a complicated phenomenon that is influenced by a variety of environmental, personal, and social factors. Social factors, in particular, may be important in promoting adherence to an exercise program in African Americans.     

我国病毒性肝炎住院费用灰色关联分析

基于2004年～2008年《中国卫生统计年鉴》和第三次国家卫生服务调查有关数据,计算病毒性肝炎现患指标,并运用灰色关联法对住院费用进行定量分析。结果显示,我国病毒性肝炎发病率为108．44／10万,病死率为0．09／10万;平均住院天数呈逐渐递减趋势;药品费用是影响住院费用的主要因素。因此,控制住院费用的增长应重点控制药品费用。     

6-12岁儿童脑电α波的发展特点

本研究以228名6～12岁儿童为研究对象,采用脑电波超慢涨落分析技术(简称ET),对其12导联脑电波(EEG)进行了记录和分析,重点探讨了α波(8～13Hz)的发展特点.结果表明:①随着年龄的增长,不同频率的α波成分表现出不同的年龄特点.②α波不同成分的比率没有明显的性别差异.③儿童α波的优势成分随年龄变化而改变.④不同年龄被试α波的平均频率存在显著差异,随着年龄的增长,6～12岁儿童α波的平均频率呈明显的上升趋势,但男女之间没有显著的性别差异.     

Phase of oral contraceptive cycle and endurance capacity of rowers

Eight female rowers (M age = 21.0 yr., SD = 2.8), using a monophasic oral-contraceptive pill, performed a 1-hr. rowing ergometer test (intensity: 70% VO2max) during the active-pill and non active-pill phases of the oral contraceptive cycle. No significant differences were found in mean energy expenditure, oxygen consumption, respiratory exchange ratio, and heart rate during the endurance test at the two phases of the oral contraceptive cycle. Mean energy expenditure rate, carbohydrate energy expenditure, lipid energy expenditure, and blood lactate during the test were not statistically significantly different among the cycle phases. In conclusion, there was no observed difference in substrate oxidation and blood lactate level during endurance rowing at different phases of the oral contraceptive cycle in these endurance-trained rowers. Endurance-trained female athletes on oral contraceptives should not worry about the possible differences in substrate oxidation during everyday training at different phases of the oral contraceptive cycle.     

Analysis of heart rate variability amongst cyclists under perceived variations of risk exposure

Cycling as a mode of travel provides an opportunity for many people to increase their levels of regular physical activity and contribute to their mental and physical health. Heart rate is often used as a means of measuring the intensity and energy expenditure of physical activity. However, heart rate is also linked to emotional factors such as anxiety and fear. Perceptions of risk due to external factors such as other road users and infrastructure may arouse such emotions in urban cyclists. The present study set out to investigate whether or not perceptions of risk among urban cyclists may lead to increased heart rates. Cyclists completed a test route in normal traffic conditions in Cork, Ireland and heart rates and self-reported risk ratings were recorded in real time. Evidence was found of a link between perceptions of risk and heart rates. This raises questions regarding the use of heart rate to estimate exercise intensity and energy expenditure during urban cycling. The perceptions of cyclists of their safety in relation to various road elements on familiar routes were also assessed, as well as specific events which they perceive to be high in risk. The results indicate that incidents involving car traffic and busy roads which offer no protection from interaction with car traffic are associated with greatest perceptions of risk.     

Repressive and defensive coping during fear and anger

In this study, the relationship between repressive and defensive coping styles and somatovisceral responses as well as emotion self-reports were investigated in 2 situational contexts conceived to induce fear and anger. Anxiety (State-Trait Anxiety Inventory; L. Laux, P. Glanzmann, P. Schaffner, and C. D. Spielberger, 1981) x Defensiveness (Marlowe-Crowne Social Desirability Scale; D. P. Crowne and D. Marlowe, 1960) x Emotion (fear, anger) moderated regression analyses revealed that compared with baseline during fear, defensiveness was related to a decrease in heart rate variability. Also during fear, repressive-defensive copers had lower self-reports of negative affect but showed higher behavioral negative affect (m. corrugator reactivity) than other participants. During anger, defensiveness was positively related to both diastolic blood pressure reactivity and m. zygomaticus reactivity. Additional analyses showed that emotional responses of repressive-defensive copers were strongly moderated by the situational context.     

Conditioned and unconditioned caloric compensation: Evidence for self-regulation of food intake in young children

The purpose of these two experiments was to determine (a) whether young children can be responsive to caloric density cues in regulating their food intake, (b) whether such cues can be associatively conditioned to organoleptic cues in foods, and (c) to obtain evidence regarding which of the many cues available are involved as conditioned stimuli. In Experiment 1 participants were eighteen 3- to 5-year-old children, who were seen for a series of pairs of conditioning trials, followed by extinction test trials. Each trial consisted of a two-part snack: approximately 100 ml of a pudding preload (chocolate or vanilla; high or low caloric density) followed after a delay by ad-lib consumption of snack foods (cookies and crackers). In extinction trials, flavors previously paired with high- or low-caloric density preloads during conditioning were presented in isocaloric intermediate density preloads. Results indicated that 14 of 18 children showed unconditioned caloric compensation on the first pair of conditioning trials; 16 of 18 children showed compensation following the second pair of trials, and 12 of these 16 subjects continued to show this consumption pattern during extinction. Consumption was significantly greater following the low calorie paired flavor than following the high calorie paired flavor during extinction. Experiment 2 (N = 10) replicated these findings, and uncorrelating preload and snack food flavors indicated that flavor cues in the preloads can serve as conditioned stimuli. Children showed both initial responsiveness to caloric density and evidence for associative conditioning of food cues to the physiological consequences of eating. These results provide initial evidence for a mechanism allowing the child to learn to anticipate the caloric consequences of familiar foods and regulate food intake accordingly.     

Self-Efficacy Relationships With Affective and Exertion Responses to Exercise1

This study examined the relationship of preexisting efficacy for exercise with perceptions of effort expenditure and in-task affect during exercise testing. Subjects comprised sedentary, middle-aged adults participating in a submaxi-mal cycle ergometer-graded exercise test. Perceptions of efficacy were assessed prior to and following exercise testing while perceptions of effort expenditure and in-task affect were assessed at 70% of predicted maxim heart rate. Highly efficacious subjects had lower perceptions of effort expenditure and reported more positive affect during exercise than did their less efficacious counterparts. Affective responses during exercise were in turn significant predictors of posttest self-efficacy. These results are discussed in regard to the importance of examining the role of personal efficacy in the formation of exercise-related affect and affective responses as sources of efficacy or competence information in exercise.