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Previous studies suggest that the magnitude of morbidity/mortality reduction may differ between race-ethnic groups despite equated dose of physical activity (PA). The purpose of this study was to compare the potential racial-ethnic differences in cardiometabolic risk factors (CMRF) across quartiles of accelerometer-derived total activity counts/day (TAC/d) among US adults. The final sample (n=4144) included adults who participated in the 2003–2006 National Health and Nutrition Examination Survey (NHANES). CMRF included fasting glucose (FG), fasting insulin (FI), HOMA-IR, resting systolic (SBP) and diastolic blood pressure (DBP), waist circumference (WC), BMI, CRP, HDL-C, LDL-C, and triglycerides. Race-ethnic groups examined included non-Hispanic white (NHW), non-Hispanic black (NHB), and Mexican American (MA). In the highest quartile, NHW had significantly lower values of HOMA-IR, FI, SBP, BMI, WC, and HDL-C when compared to NHB. Compared to MA in the highest quartile, NHW had significantly lower values of HOMA-IR, FI, BMI, and triglycerides. Significant race-ethnic differences were found for several CMRF, especially among those who were in the top quartile of PA (e.g., the most active adults). It is probable that the protective effect of higher volumes of PA on CMRF is moderated by other non-PA factors distinct to NHB and MA.

A study investigates the physical activity levels and body mass index (BMI) of Old Order Amish children and adolescents living in a nontechnological farming community. Results prove that Amish youth are physically more active and have a lower rate of obesity, as compared to the children with all the modern facilities of industrialization.

The determination of energy expenditure can be accomplished by simultaneous heart rate-motion sensor technique during free-living activity. The simultaneous heart rate-motion sensor data show significant relationship with heart rate-oxygen uptake.

This article presents a model for measuring the relationship between heart rate and energy expenditure. An analysis of energy metabolism, oxygen consumption, and exercise intensity is presented.

This article discusses the physiological aspects of brisk walking on high blood pressure in post-menopausal women. Topics include body composition, food habits, and cardiovascular disease risk reduction.

This article presents a standardized method of classifying physical activities according to activity type and intensity level. Each activity is assigned a numerical code and a MET value that represents a ratio of the working metabolic rate for the task and a standard resting rate.

This article evaluates the validity of using motion sensors to estimate the energy costs of moderately intense activities such as gardening, housework, and outdoor recreation. Results indicate that motion sensors underestimated the energy expenditure involved in many activities due to their inability to include data from upper body movements.

This article examines the validity of using heart rate measures taken during moderately vigorous exercise to estimate energy metabolism. Results indicate that heart rate measures were correlated with oxygen consumption levels and provided accurate, objective, and noninvasive estimates of energy expenditure.

This article compares the accuracy of using motion sensors, daily written logs, or weekly telephone surveys to measure the amount of time spent on household, recreational, or occupational physical activities. Results indicate that the three measurement methods produced similar estimates of time spent on moderate and intense physical activities.

This article examines the accuracy of using hip and wrist accelerometers to measure the energy costs of housework, yardwork, and recreational activities. Results indicate that adding the data from the wrist accelerometer to hip measurements resulted in minimal improvements in accuracy that were offset by the additional equipment costs.

Use of a questionnaire vs use of a pedometer for measurement of daily walking distance has been studied. Subjects were found to underestimate daily walking distance of the College Alumnus questionnaire (CAQ) vs the pedometer. Energy expended on walking was correspondingly lower on the CAQ vs the pedometer-derived values.

Results demonstrate that endurance training improves performance by increasing fat oxidation and lowering lactic acid accumulation at a given oxygen partial pressure. Data further show that lactate threshold is the best physiological predictor of endurance.

Field crank dynamometer measurements and mathematical models indicate that a cyclist uses over 440 Watts of power in 1 h at the sea level and less riding at altitude. Study also shows that recent rise in the hour record is influenced by aerodynamic advances and higher power outputs of cyclists over the years.

The relation of age and body mass index (BMI) to atherosclerosis risk factors was examined in 357 men. Older ([is greater than or equal to 45 years) men had higher (p < 0.01) systolic and diastolic blood pressures, fasting cholesterol and glucose, and 1-hour glucose and insulin levels. Fasting insulin and triglyceride levels were not significantly different between the 2 age groups. Although older men (n = 170) had greater values for several risk factors, overweight (BMI >25.5 kg/[m.sup.2]) increased risk factors more in men younger than 45 years (n = 187). In younger men, those with higher BMIs had a greater prevalence, respectively, of blood pressure >140/90 mm Hg (35.2 vs 11.2%, p 200 mg/dl (53.5 vs 29.3%, p 150 mg/dl (38.0 vs 10.3%, p 160 mg/dl (15.5 vs 5.2%, p 11 [mu]U/ml (28.2 vs 5.2%, p 110 [mu]U/ml (28.2 vs 9.5%, p, Obesity is known to be a risk factor for the development of high blood pressure, cardiovascular disease, and premature death, among other complications. The degree of added risk conferred by obesity is not uniform across all age groups. Younger overweight men have been found to be at greater additional risk for cardiovascular disease and premature death than older overweight men. To investigate other possible age-related differences in cardiovascular risk factors among obese men, data obtained from 357 men (both normal and obese) who had been referred to an atherosclerosis clinic were evaluated. Older men (over 45 years old), as a whole, had higher values on some cardiovascular risk factors (blood pressure, fasting cholesterol and glucose levels). In younger men, being overweight was associated with increased blood pressure, cholesterol levels, fasting triglycerides (fat), glucose, and insulin. In older men, only insulin levels were elevated in the overweight group. Hence, excessive weight increases the prevalence of cardiovascular risk factors to a greater extent in men under 45. This may reflect the fact that in older men, the risk factors are already elevated relative to younger men, and the obesity is not severe enough a challenge to raise them any further. (Consumer Summary produced by Reliance Medical Information, Inc.)

The study provides descriptive, epidemiological data on the average number of steps per day taken by U.S. adults and identifies predictors of pedometer-measured physical activity based on demographic and self-reported behavioral characteristics. Results show U.S. adults take fewer steps than those in Switzerland, Australia and Japan, suggesting that low levels of ambulatory physical activity contribute to the high prevalence of adult obesity in the U.S.

A study was conducted to refine the 2006 Crouter two-regression model to eliminate the misclassification of walking or running when starting an activity in the middle of a minute on the ActiGraph clock. The change of activities that start and stop in the middle of a minute on the ActiGraph clock would help to refine the two-regression model to facilitate the elimination of the misclassification of transitional minutes and improve the estimate of free-living energy expenditure.

A study is conducted to compare the classic physiological variables linked to endurance performance and running economy (RE)) with peak treadmill velocity (PTV) as predictors of performance in a 16-km time trial. The PTV is associated to the same physiological variables that determine vV[spacing dot above]O2max.

The study determines if any differences exist between activity counts from the ActiGraph 7164 and three versions of the ActiGraph GT1M. Findings reveal no statistically significant differences between output from all accelerometers, indicating that any of the four ActiGraph versions may be used during research.

The study examines the influence of modernity on the physical activity behaviors of children living a traditional lifestyle in Old Order Amish and Mennonite communities as compared with children living a contemporary lifestyle. Results suggest that contemporary or modern living is associated with lower levels of moderate- and vigorous-intensity physical activity in comparison with the lifestyles of earlier generations.

The effects of body mass index (BMI), waist circumference, and pedometer tilt were examined on the accuracy of a spring-levered pedometer and a piezo-electric pedometer during treadmill walking and over a 24-hour period in overweight and obese adults. A piezo-electric pedometer is found to be more accurate than a spring-levered pedometer, especially at slower walking speeds, and the most important factor influencing the accuracy of the spring-levered pedometer.

The relationship between pedometer-determined physical activity and body composition variables in middle-aged, African-American women is evaluated. Conclusions reveal that middle-aged, African-American women who accumulate more ambulatory activity have significantly lower body fat percentages, body mass index values, waist circumferences, and hip circumferences.

Accuracy of the Polar S410 for estimating gross energy expenditure (EE) during exercise when using both predicted and measured VO(sub 2max) and HR(sub max) versus indirect calorimetry (IC) is examined. The result reveals that when the predicted values of VO(sub 2max) and HR(sub max) are used, the Polar S410 heart rate monitor provides a rough estimate of EE during running, rowing, and cycling.

A group of ten males and ten females ranging in body mass index (BMI) from 19.8 to 35.4 kg.m (super -2) wear two pedometers for a 24-hr period to compare the step values of multiple brands of the machine. The brands, Kenz Lifecorder (KZ), Yamax Digi-Walker SW-200 (YX200), New-Lifestyles NL-2000 (NL) and Yamax Digi-Walker SW-701 (YX701), of pedometers are found to be more suitable for research purpose as they were more accurate than the others used.

A study was conducted to examine the influence of modern technology on physical activity, the magnitude of decline of physical activity levels and the measures of adiposity in the members of Old Order Amish community. The study revealed the high level of physical activity, which exceeded the minimum recommendations specified in the public health guidelines.

This article discusses variation in accuracy of the pedometers evaluated. Data indicate that Ymax brand pedometer is superior in terms of its accuracy and reliability followed by NL and KZ types.

Results reveal that pedometers accurately measure steps but less accurate for measuring distance and even less so in quantitating energy consumption in terms of kilocalories.

IMPORTANCE: A goal of 10 000 steps/d is commonly believed by the public to be necessary for health, but this number has limited scientific basis. Additionally, it is unknown whether greater stepping intensity is associated with health benefits, independent of steps taken per day. OBJECTIVE: To examine associations of number of steps per day and stepping intensity with all-cause mortality. DESIGN, SETTING, AND PARTICIPANTS: This prospective cohort study included 18 289 US women from the Women’s Health Study who agreed to participate by wearing an accelerometer during waking hours for 7 days between 2011 and 2015. A total of 17 708 women wore and returned their devices; data were downloaded successfully from 17 466 devices. Of these women, 16 741 were compliant wearers (≥10 h/d of wear on ≥4 days) and included in the analyses, which took place between 2018 and 2019. EXPOSURES: Steps per day and several measures of stepping intensity (ie, peak 1-minute cadence; peak 30-minute cadence; maximum 5-minute cadence; time spent at a stepping rate of ≥40 steps/min, reflecting purposeful steps). MAIN OUTCOMES AND MEASURES: All-cause mortality. RESULTS: Of the 16 741 women who met inclusion criteria, the mean (SD) age was 72.0 (5.7) years. Mean step count was 5499 per day, with 51.4%, 45.5%, and 3.1% of time spent at 0, 1 to 39 (incidental steps), and 40 steps/min or greater (purposeful steps), respectively. During a mean follow-up of 4.3 years, 504 women died. Median steps per day across low-to-high quartiles of distribution were 2718, 4363, 5905, and 8442, respectively. The corresponding quartile hazard ratios (HRs) associated with mortality and adjusted for potential confounders were 1.00 (reference), 0.59 (95% CI, 0.47-0.75), 0.54 (95% CI, 0.41-0.72), and 0.42 (95% CI, 0.30-0.60), respectively (P &lt; .01). In spline analysis, HRs were observed to decline progressively with higher mean steps per day until approximately 7500 steps/d, after which they leveled. For measures of stepping intensity, higher intensities were associated with significantly lower mortality rates; however, after adjusting for steps per day, all associations were attenuated, and most were no longer significant (highest vs lowest quartile for peak 1-minute cadence, HR = 0.87 [95% CI, 0.68-1.11]; peak 30-minute cadence, HR = 0.86 [95% CI, 0.65-1.13]; maximum 5-minute cadence, HR = 0.80 [95% CI, 0.62-1.05]; and time spent at a stepping rate of ≥40 steps/min, HR = 1.27 [95% CI, 0.96-1.68]; P > .05). CONCLUSIONS AND RELEVANCE: Among older women, as few as approximately 4400 steps/d was significantly related to lower mortality rates compared with approximately 2700 steps/d. With more steps per day, mortality rates progressively decreased before leveling at approximately 7500 steps/d. Stepping intensity was not clearly related to lower mortality rates after accounting for total steps per day.

Purpose: Determine the effects of television viewing on enjoyment of exercise in college students. Methods: Forty-three college students (Mean ± SD; age = 19 ± 2 y, body mass index (BMI) = 23.7 ± 3.2 kg/m2) completed two 30-minute cycling exercise sessions at a moderate exercise intensity (40% peak oxygen consumption), in randomised order. Experimental session required participants to view a nature series programme (TV), while in the control session they did not watch television (No-TV). Rating of Perceived Exertion (RPE) and Feeling Scale (FS) were measured at 10, 20 and 30 minutes of exercise. The Physical Activity Enjoyment Scale was administered following each session. Enjoyment of exercise was analysed with a paired samples t-test. Additional analyses were conducted to assess the influence of potential physiological and psychological mediators of exercise enjoyment. Correlational analyses were conducted to determine the relationship between mean FS values and enjoyment of exercise for each visit. Repeated measures ANOVAs (condition x time) were performed on RPE. Results: Enjoyment of exercise was higher for TV (87 ± 19) vs. No-TV (79 ± 1 6) (p = .016) and was positively correlated with intrinsic motivation (r = 0.347) (p < .05). Mean FS values were correlated with enjoyment for both conditions (p < .05). No differences in RPE between sessions were observed (p = .127). Conclusion: Watching television during exercise may positively enhance the overall experience and promote enjoyment of exercise.

This article examines the reliability of using an accelerometer, an exercise assessment tool, in a physical activity measurement study.

David R. Bassett--UCAR Emulsion Systems [*] One of the chief requirements of protective coatings is the ability to confer water resistance to painted substrates. To accomplish this task, the coating [...]

This paper presents a study on physical activity implications of electric bikes, focusing on the users of an on-campus conventional bicycle and e-bike sharing system at the University of Tennessee. The study describes field trials of 17 users of the bikesharing system and investigates physical activity metrics on identical trips made by three different modes: walk, conventional bicycle, and pedal-assist electric bicycle. The users completed a hilly 4.43 kilometer route using each mode. Heart rate and human power output were monitored along with GPS for each bout. In addition, the study used a laboratory test to relate oxygen consumption rate (VO2in ml/kg/min) and energy expenditure (EE kcal/kg/min) to user heart rate during bouts. Energy expenditure and ventilation rates (per minute) for all modes were not statistically different. However, total EE and VO2for each bout (per mile) for e-bikes are 24% lower than that for conventional bicycles, and 64% lower than for walking. This reflects the shorter travel time. Differences between e-bikes and bicycles are most pronounced on the uphill segment. Still, e-bikes provide moderate physical activity (MET>3) on flat segments and downhill segments, and vigorous physical activity (MET>6) on uphill segments. For e-bike trials, riders reported higher levels of enjoyment and lower need for a shower than walk or conventional bicycle trials. This paper adds to the expanding literature by comparing e-bike, bicycle and walk EE and VO2. E-bikes can contribute as an active transportation mode to meet required physical activity guidelines.

Worksites are continuing to use wellness programs to encourage employees to adopt and maintain healthy behaviors. Some of these programs offer financial incentives to maximize employee participation and motivate behavior change. Purpose:The purpose of this study was to gather information regarding a financially incentivized worksite wellness program at a Southeastern United States university. Participants:A 15-item electronic survey was distributed to participants enrolled in the Virgin Pulse HealthMiles (VHM) program at Belmont University. Methods:Steps per day were uploaded to the VHM website by program enrollees (N = 458). The survey inquired about physical activity habits, motivating factors, and improvements in cardiovascular disease risk factors since joining the program. Results:VHM enrollees took an average of 7321 steps/day, as measured by objective pedometer data. Among the 146 respondents, the most motivating factor for participation was the financial incentive, which was considered ‘strongly motivating’ by 64%. About 82% reported being more physically active, 71% felt better, 57% had more energy, and 56% had lost weight since joining the program. The average self-reported weight loss was 7 ± 12 lb (mean ± SD). About 87% indicated they would recommend this program to a friend. Conclusions:The enrollees in the VHM program are taking about 2000 steps/day more than the average American. Most of the people who responded to the survey reported that their physical activity had increased since starting the program. The financial incentive was the most motivating factor to participate.

Active workstations, such as treadmill and sit-to-stand workstations, enable office employees to break prolonged sitting with bouts of light-intensity walking and/or standing. Compared with sitting, walking and/or standing accumulated during the workday using these workstations will increase muscle contractions, which may influence blood flow, energy expenditure, metabolism, musculoskeletal health, and brain function. Physiological responses when using treadmill and sit-to-stand workstations may vary due to differences in muscle contraction type (dynamic vs. static) and may thus affect cardio-metabolic and musculoskeletal health and brain function in different ways.

Purpose. To investigate the implementation of state- and school-mandated physical education (PE) and physical activity policies on students' school-day physical activity behaviors.Design. Observational, cross-sectional study.Setting. Five elementary schools in rural Alabama.Subjects. Six hundred and eighty-three school-age children.Measures. School-day physical activity behaviors were assessed with pedometer step count, the System for Observing Fitness Instruction Time (SOFIT), and the System for Observing Play and Leisure Activity in Youth (SOPLAY).Analysis. Descriptive statistics (means and standard deviations) were used to describe the current health and in-school physical activity behaviors of students.Results. Students accumulated a daily average of 4079.57 (± 1678.1) and 3473.44 (± 1073.37) steps for boys and girls, respectively, throughout the school day. SOFIT findings indicate that students spent an average of 23.80 ± 5.33 min/d in PE and that 14.33 ± 6.10 min/d were spent in moderate to vigorous physical activity (MVPA). This equates to 59.38% of PE time spent in MVPA. SOPLAY findings showed that recess and before/after school activity was not provided.Conclusions. It appears that schools were in compliance with the state-mandated PE policies on paper but not in actuality. Students did not attend PE for 30 min/d. The implementation of PE as the sole physical activity opportunity provides inadequate amounts of physical activity during the school day.

The article reports on the release of the School Health Guidelines to Promote Healthy Eating and Physical Activity by the U.S. Centers for Disease Control and Prevention (CDC) in 2013. The guideline includes recommendations for school-based policies intended to increase physical activity in schoolchildren (K-12). The guideline concludes that some approaches increase effectively physical activity among youth, such as adopting physical education curricula and physical education classes.

Introduction:The goal of 10,000 steps/day is widely promoted. There is limited evidence, however, of the number of steps/day associated with risk of developing cardiovascular disease (CVD).Hypothesis:We hypothesize a dose-response association between higher device-measured steps/day with lower CVD incidence.Methods:The Steps for Health Collaborative conducted a meta-analysis of seven prospective studies with device-measured steps/day and followed participants for CVD events. Participants without CVD at baseline were included. CVD was defined as coronary heart disease, stroke, and/or heart failure. Data were analyzed at the study level. Study-specific associations of quartiles of steps/day with incident CVD was assessed using Cox proportional hazards regression models and summarized using random effects meta-analysis. Models were adjusted for age, race/ethnicity, sex, body mass index, device wear time, and study-specific indicators for education or income, smoking, alcohol intake, blood pressure, dysglycemia, and hyperlipidemia. Study heterogeneity was assessed using I2 statistic.Results:The meta-analysis included 16,906 adults (mean age 62 years; 51% women), with median follow-up of 6.3 years (limits 2.9-10.7 years) and 1370 (8.1%) CVD events. Medians of study-specific steps/day were 1,951 (first quartile, Q1), 3,823 (second quartile, Q2), 5,685 (third quartile, Q3), and 9,487 (fourth quartile, Q4). Compared with Q1, summary hazard ratios for CVD were 0.83 (Q2, 95% confidence interval 0.72-0.95), 0.68 (Q3, 0.58-0.80), and 0.60 (Q4, 0.47-0.78) (Figure). There was low to moderate heterogeneity; I2 values were 0% for Q2, 2% for Q3, and 37% for Q4.Conclusions:Higher steps/day were associated with progressively lower risk of CVD. Monitoring and promoting steps/day can be a simple, easy to interpret metric used for clinician-patient communication and population health to reduce the risk of CVD.

Purpose. This study was designed (1) to examine the effects of a 10,000 steps·d−1exercise prescription on sedentary, overweight/obese adults, and (2) to examine the effects of adherence on body composition and cardiovascular risk factors.Methods. Fifty-six overweight/obese adults participated in the study. Body composition and cardiovascular risk factors were determined at baseline, 20 weeks, and 36 weeks. Adherence was defined as averaging ≥ 9500 steps·d−1from week 4 to week 36.Results. 38 participants (68%) wore pedometers daily for 36 weeks and were available for posttesting. Significant improvements were noted in mean values for walking volume (3994 steps·d−1), body weight (–2.4 kg), body mass index (–0.8 kg·m−2), percentage body fat (–1.9%), fat mass (–2.7 kg), waist circumference (–1.8 cm), hip circumference (–1.9 cm) and high-density lipoprotein (3 mg/dl). The adherers had large improvements in body composition measures, whereas the nonadherers showed little or no change in these variables.Discussion. A 10,000 steps·d−1exercise prescription resulted in weight loss over 36 weeks in previously sedentary, overweight/obese adults. Adherence to the step goal had a marked effect on the outcome.

Individuals exhibiting “the metabolic syndrome” have multiple coronary artery disease risk factors, including insulin resistance, hyperlipidemia, hypertension, and android obesity. We performed a randomized trial to compare the effects of aerobic and resistance training regimens on coronary risk factors. Twenty-six volunteers who exhibited android obesity and at least one other risk factor for coronary artery disease were randomized to aerobic or resistance training groups. Body mass index, waist-to-hip ratio, glucose, insulin, body composition, 24-hr urinary albumin, fibrinogen, blood pressure, and lipid profile were measured at baseline and after 10 weeks of exercise training. Both groups showed a significant reduction in waist-to-hip ratio and the resistance training group also showed a reduction in total body fat. There was no significant change in mean arterial blood pressure in either group. Fasting plasma glucose, insulin, total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides were unchanged in both groups. High-density lipoprotein (HDL) cholesterol increased (13%) with aerobic training only. Plasma fibrinogen was increased (28% and 34%, P< 0.02) in both groups and both groups showed a significant decrease (34% and 28%, P< 0.03) in microalbuminuria after their respective training regimen. In conclusion, resistance training was effective in improving body composition of middle-aged obese sedentary males. Only aerobic training was effective in raising HDL cholesterol. More studies are warranted to assess the effects of exercise on plasma fibrinogen and microalbuminuria.

Beginning in 1910, A. V. Hill performed careful experiments on the time course of heat production in isolated frog muscle. His research paralleled that of the German biochemist Otto Meyerhof, who measured the changes in muscle glycogen and lactate during contractions and recovery. For their work in discovering the distinction between aerobic and anaerobic metabolism, Hill and Meyerhof were jointly awarded the 1922 Nobel Prize for Physiology or Medicine. Because of Hill's interest in athletics, he sought to apply the concepts discovered in isolated frog muscle to the exercising human. Hill and his colleagues made measurements of O2consumption on themselves and other subjects running around an 85-m grass track. In the process of this work, they defined the terms “maximum O2intake,” “O2requirement,” and “steady state of exercise.” Other contributions of Hill include his discoveries of heat production in nerve, the series elastic component, and the force-velocity equation in muscle. Around the time of World War II, Hill was a leading figure in the Academic Assistance Council, which helped Jewish scientists fleeing Nazi Germany to relocate in the West. He served as a member of the British Parliament from 1940 to 1945 and as a scientific advisor to India. Hill's vision and enthusiasm attracted many scientists to the field of exercise physiology, and he pointed the way toward many of the physiological adaptations that occur with physical training.

The accuracy of a computerized metabolic system, using inspiratory and expiratory methods of measuring ventilation, was assessed in eight male subjects. Gas exchange was measured at rest and during five stages on a cycle ergometer. Pneumotachometers were placed on the inspired and expired side to measure inspired (V˙i) and expired ventilation (V˙e). The devices were connected to two systems sampling expired O2and CO2from a single mixing chamber. Simultaneously, the criterion (Douglas bag, or DB) method assessed V˙eand fractions of O2and CO2in expired gas (FeO2and FeCO2) for subsequent calculation of O2uptake (V˙o2), CO2production (V˙co2), and respiratory exchange ratio. Both systems accurately measured metabolic variables over a wide range of intensities. Though differences were found between the DB and computerized systems for FeO2(both inspired and expired systems), FeCO2(expired system only), andV˙o2(inspired system only), the differences were extremely small (FeO2= 0.0004, FeCO2= −0.0003,V˙o2= −0.018 l/min). Thus a computerized system, using inspiratory or expiratory configurations, permits extremely precise measurements to be made in a less time-consuming manner than the DB technique.

During an incremental run test, some researchers consistently observe a heart rate (HR) deflection at higher speeds, but others do not. The present study was designed to investigate whether differences in test protocols could explain the discrepancy. Additionally, we sought to determine whether the HR deflection point accurately predicts lactate threshold (LT). Eight trained runners performed four tests each:1) a treadmill test for maximal O2uptake,2) a Conconi test on a 400-m track with speeds increasing ∼0.5 km/h every 200 m,3) a continuous treadmill run with speeds increasing 0.5 km/h every minute, and4) a continuous LT treadmill test in which 3-min stages were used. All subjects demonstrated an HR deflection on the track, but only one-half of the subjects showed an HR deflection on the treadmill. On the track the shortening of stages with increasing speeds contributed to a loss of linearity in the speed-HR relationship. Additionally, the HR deflection point overestimated the LT when a continuous treadmill LT protocol was used. In conclusion, the HR deflection point was not an accurate predictor of LT in the present study.

The dissolution behavior of a hydrophobic alkali-swellable emulsion (HASE) in water was examined by dynamic light scattering and pyrene fluorescence probe experiments. The HASE polymer was obtained by the copolymerization of ethyl acrylate (EA), methacrylic acid (MAA), and a macromonomer containing a C20H41group separated from the polymer backbone by 32 ethylene oxide units. The behavior of the copolymer was followed as a function of the neutralization degree = [NaOH]/[COOH] of the MAA component. Particles swell with increasing until = 0.4 after which polymer dissolution begins. At low , pyrene, added as a probe to the solution, dissolves in the EA-MAA copolymer phase; whereas at high , pyrene is largely localized in C20H41micelles. Pyrene fluorescence measurements show that the striking viscosity increase of the solution with increasing correlates with polymer dissolution and intermolecular network formation. Key words: associative polymer, hydrophobic substituents, polymeric micelles.

Despite the fact that swimming is often recommended for the prevention and treatment of hypertension, no study has examined the potential efficacy of regular swimming exercise for lowering the blood pressure in hypertensive humans.

The traditional view of VO2maxowes a great deal to the work of A. V. Hill, who conducted experiments on exercising man in Manchester, England, in the 1920's. Hill and colleagues proposed that there is an upper limit to oxygen uptake (VO2max), that there are inter-individual differences in this variable, and that VO2maxis limited by the circulatory and/or respiratory systems. They demonstrated that oxygen uptake increases linearly with running speed, but in some subjects it eventually“reaches a maximum beyond which no effort can drive it,” a phenomenon now referred to as the VO2plateau. In recent years, Timothy Noakes has strongly criticized Hill's concept of VO2max. He maintains that the absence of a VO2plateau in some subjects is proof that oxygen delivery is not a limiting factor for VO2max. This view fails to recognize that the plateau is not the principal evidence for a cardiorespiratory limitation. Noakes rejects the VO2maxparadigm of A.V. Hill in its entirety. The alternative paradigm he proposes is that endurance performance is limited by “muscle factors.” Noakes suggests that the best distance runners have muscle characteristics that allow them to achieve higher running speeds, and since running speed is linearly related to oxygen uptake, an indirect consequence of this is that they will have higher VO2maxvalues. This is exactly the opposite of how the relationship between VO2maxand running speed at the end of a maximal exercise test should be viewed. Noakes offers little evidence to support his views, and they conflict with a vast body of scientific evidence showing that oxygen transport is a major determinant of endurance performance. After carefully reviewing the evidence on both sides of the issue, we conclude that the older “classical” VO2maxparadigm of A.V. Hill is the correct one.

In calculating the physical activity index (PAI) on the college alumnus questionnaire, it is assumed that 8 kcal are expended for every 20 steps climbed. This value is equal to an energy cost of 0.40 kcal·step-1. Since it is assumed that subjects climb and descend an equal number of stairs, the total value reflects the energy cost of stepping up (estimated at 0.30 kcal·step-1) and stepping down(estimated at 0.10 kcal·step-1). However, these values appear to be based on theoretical calculations rather than empirical observation. The purpose of this study was to quantify the energy cost of stair climbing and stair descending by measuring oxygen uptake. Twenty subjects performed continuous stair-climbing and stair-descending on an escalator at a stepping rate of 70 steps·min-1. Heart rate was monitored by telemetry, and oxygen uptake was measured by the Douglas bag technique from 5 to 7 min. Results showed that the gross energy cost of stair climbing is 8.6 METs, and that of stair descending is 2.9 METs. Thus, for a 70-kg person the gross caloric costs of ascending stairs (0.15 kcal·step-1) and descending stairs (0.05 kcal·step-1) are one-half of the values previously assumed. In conclusion, the algorithm for calculating PAI on the college alumnus questionnaire should be modified to reflect a total cost of 0.20 kcal for going up and down one step. Even more precise estimates can be obtained by adjusting for body weight (going up and down one flight of stairs requires 1.63 MET·min).

BASSETT, D. R. Jr. and T. R. FITTON. Gas mixing apparatus for determining cardiac output by CO2rebreathing. Med. Sci. Sports Exert:, Vol. 27, No. 12, pp. 1698–1702, 1995. The carbon dioxide rebreathing technique is widely used for determination of cardiac output during exercise. The equilibration method of Collier et al. (J. Appl. Physiol.9:25, 1956) is generally preferred over the exponential method of Defares (J. Appl. Physiol.13:159, 1968). However, the equilibration method requires the volume and initial CO2percentage in the rebreathing bag to be adjusted according to the work rate. A device for mixing two gases (100 O2and 20 CO2/80 O2) was constructed for this purpose. Multistage regulators are attached to the gas tanks and connected to a medical gas mixer via high-pressure air hoses. A variable time-delay switch causes a solenoid valve to open for 1.0–10 s to deliver a predetermined gas volume. The device was found to accurately deliver a preset volume and concentration of gas to the rebreathing bag. A gas mixing apparatus simplifies the equilibration CO2rebreathing technique by allowing the investigator to easily select the initial volume and percentage of CO2.

BASSETT, DAVID R., JR., MICHAEL D. GIESE, FRANCIS J. NAGLE, ANN WARD, DIANE M. RAAB, and BRUNO BALKE. Aerobic requirements of overground versus treadmill running. Med. Sci. Sports Exerc., Vol. 17, No. 4, pp. 477-481, 1985. There is general agreement that the oxygen demand of level running is similar for both the treadmill (TM) and overground situations at speeds under 260 m·min-1. However, controversy exists with regard to inclined running. The prevailing view, represented by the ACSM prediction formulas, is that overground hill running is theoretically more costly than inclined treadmill running. This study was designed to investigate the problem from an empirical standpoint. Seven male subjects performed overground and TM running at two grades (0 and 5.7) over a range of speeds between 136-286 m·min-1. For the outdoor trials, subjects covered a distance of 950 m at a constant pace, and expired gas was collected over the last 150 m. Matching trials were then performed on the treadmill at the same speed and grade. Regression lines were calculated for speed vs oxygen consumption (O2). For TM and overground level running, these were

BASSETT, JR., D. R., F. J. NAGLE, S. MOOKERJEE, K. C. DARR, A. V. NG, S. G. VOSS, and J. P. NAPP. Thermoregulatory responses to skin wetting during prolonged treadmill running. Med. Sci. Sports Exerc., Vol. 19, No. 1, pp. 28–32, 1987. We examined the physiological responses to skin wetting during a 120-min level treadmill run to assess whether skin wetting would reduce the dehydration and the increase in core temperature associated with prolonged exercise. Testing was conducted in an environmental chamber (T = 29.5°C, wind velocity = 3 m·sec-1) under two different humidity conditions (33 or 66 relative humidity). Ten male subjects performed two runs in each humidity condition; one served as a control run. The other included spraying the body with 50 ml of water (T = 29.5°C) every 10 min. Spraying had no effect on rectal temperature (Tre), heart rate, oxygen consumption, perceived exertion, sweat loss, or percent change in plasma volume in both the humid and the dry conditions. Spraying produced a significant reduction in mean skin temperature (sk), which increased the (Tre- sk) gradient. At the same time, overall skin conductance (K) was decreased, presumably as a result of cutaneous vasoconstriction due to the low sk. Since heat transfer from the body's core to the skin is expressed by the equation: