Uncertainty in monetary cost estimates for assessing working postures using inclinometry, observation or self-report.

OBJECTIVE: To assess uncertainty in cost estimates for collecting posture data by inclinometry, observations and self-report. METHOD: In a study addressing physical workloads at a paper mill, costs were calculated for measuring postures of twenty-eight workers during three shifts. Uncertainty in costs was assessed for all three methods as the range between an assumed best case (lowest cost) and worst case (highest cost) using scenario analysis. RESULTS: The cost for observation was larger, but also more uncertain (€16506 and €89552 in the best and worst case, respectively) than that of inclinometry (€7613 - €45896). Self-report costs were both lower and less uncertain (€3743 - €23368). CONCLUSIONS: The extent of uncertainty in cost estimates implies that observation could be less expensive than inclinometry, e.g., in a scenario where experienced observers could use existing software, while inclinometers would have to be purchased. We propose adding uncertainty assessments to cost estimates when selecting a method for measuring working postures, and offer guidance in how to proceed in a specific setting.

The Effectiveness of Standing on a Balance Board for Increasing Energy Expenditure.

PURPOSE: This study aimed to investigate differences in energy expenditure (EE), heart rate (HR), productivity, fatigue, and pain while performing desk work while sitting (SIT), standing (STAND), and standing on a balance board (BOARD). METHODS: Thirty healthy adults (60% female, age = 39.7 ± 11.8 yr, body mass index = 26.7 ± 5.0 kg·m) employed in sedentary-based jobs volunteered for this randomized crossover trial. Participants performed typing work in three different positions: SIT, STAND, and BOARD, each condition lasting 30 min. Oxygen consumption (V˙O2) was measured via indirect calorimetry, and EE was calculated using respiratory quotient and corresponding caloric equivalent values. Productivity was quantified by measuring words typed per minute, accuracy, and typing mistakes. Overall feelings of fatigue and pain were self-reported three times during each position using validated 10-cm visual analog scales. Repeated-measures ANOVA was used to assess differences in outcome variables across conditions. RESULTS: V˙O2 was significantly different among all conditions regardless of current standing desk use (SIT = 3.35 ± 0.53, STAND = 3.77 ± 0.48, BOARD = 3.92 ± 0.54 mL·kg·min, P < 0.001). EE (kcal·min) also differed (P < 0.001) among SIT (1.27 ± 0.22), STAND (1.42 ± 0.26), and BOARD (1.48 ± 0.29). Compared with sitting (67 ± 9 bpm), HR was higher in STAND (76 ± 11 bpm) and BOARD (76 ± 11 bpm, P < 0.001). Measures of productivity were not different across conditions (P > 0.05). Fatigue progressively increased over each 30-min condition, whereas pain in SIT and BOARD increased from minute 10 to minute 20 and then leveled off between minutes 20 and 30. For STAND, pain continued to increase over time. CONCLUSION: Compared with sitting, a balance board may be effective for increasing EE without interfering with productivity in an occupational setting.

Gross efficiency and cycling economy are higher in the field as compared with on an Axiom stationary ergometer.

This study was designed to examine the biomechanical and physiological responses between cycling on the Axiom stationary ergometer (Axiom, Elite, Fontaniva, Italy) vs. field conditions for both uphill and level ground cycling. Nine cyclists performed cycling bouts in the laboratory on an Axiom stationary ergometer and on their personal road bikes in actual road cycling conditions in the field with three pedaling cadences during uphill and level cycling. Gross efficiency and cycling economy were lower (-10%) for the Axiom stationary ergometer compared with the field. The preferred pedaling cadence was higher for the Axiom stationary ergometer conditions compared with the field conditions only for uphill cycling. Our data suggests that simulated cycling using the Axiom stationary ergometer differs from actual cycling in the field. These results should be taken into account notably for improving the precision of the model of cycling performance, and when it is necessary to compare two cycling test conditions (field/laboratory, using different ergometers).

Assessing the development and application of the accelerometry technique for estimating energy expenditure.

A theoretically valid proxy of energy expenditure is the acceleration of an animal's mass due to the movement of its body parts. Acceleration can be measured by an accelerometer and recorded onto a data logging device. Relevant studies have usually derived a measure of acceleration from the raw data that represents acceleration purely due to movement of the animal. This is termed 'overall dynamic body acceleration' (ODBA) and to date has proved a robust derivation of acceleration for use as an energy expenditure proxy. Acceleration data loggers are generally easy to deploy and the measures recorded appear robust to slight variation in location and orientation. This review discusses important issues concerning the accelerometry technique for estimating energy expenditure and ODBA; deriving ODBA, calibrating ODBA, acceleration logger recording frequencies, scenarios where ODBA is less likely to be valid, and the power in recording acceleration and heart rate together. While present evidence suggests that ODBA may not quantify energy expenditure during diving by birds and mammals, several recent studies have assessed changes in mechanical work in such species qualitatively through variation in ODBA during periods of submergence. The use of ODBA in field metabolic studies is likely to continue growing, supported by its relative ease of use and range of applications.

RT3 accelerometer shoulder activity: discrimination of activity levels by the RT3 accelerometer for the assessment of shoulder physical activity (SPA).

We investigated whether the RT3 accelerometer can be used to discriminate and characterize the different levels of shoulder physical activity (SPA) in both patients and healthy adults. Twenty healthy adults and 20 patients with shoulder disorders (SDs) performed activities at 5 levels of difficulty (easy, easy-moderate, moderate, hard-moderate, hard) with the same RT3 accelerometer fixed on the arm. The Vector Magnitude (VM) is the square root of the sum of squares from each axis to determine the overall magnitude of activity. The SPA counts of healthy group were significantly higher than the patient group in every level except easy (31-38 VM counts difference, p < 0.01). For both groups, the hard task demonstrated higher counts as compared to the other tasks. The easy task showed lower counts as compared to the other tasks. In the patient group, significant correlation between FLEX-SF scores and counts from the RT3 (R = -0.72, p < 0.05) was found in the moderate tasks. The results of this study showed that RT3 can be a potential measurement tool to (1) characterize the difference of SPA between two groups; and (2) partially discriminate the different levels of SPA. The correlations between self-reported function scores and SPA RT3 counts are dependent on self-reported task difficulty.

Convergent validity of 3 low cost motion sensors with the ActiGraph accelerometer.

BACKGROUND: This study evaluated the utility of several lower cost physical activity (PA) assessment instruments for detecting PA volume (steps) and intensity (time in MVPA or activity time) using convergent methods of assessment. METHODS: Participants included 26 adults (9 male) age 27.3 ± 7.1 years with a BMI of 23.8 ± 2.8 kg/m2. Instruments evaluated included the Omron HJ-151 (OM), New Lifestyles NL-1000 (NL), Walk4Life W4L Pro (W4L), and ActiGraph GT1M (AG). Participants wore all instruments during a laboratory phase, consisting of 10 single minute treadmill walking bouts ranging in speed from 40 to 112 m/min, and immediate following the laboratory phase and during the remainder of their free-living day (11.3 ± 1.5 hours). Previously validated AG MVPA cutpoints were used for comparison with OM, NL, and W4L MVPA or activity time outputs during the laboratory and free-living phase. RESULTS: OM and NL produced similar MVPA estimates during free-living to commonly used AG walking cutpoints, and W4L activity time estimates were similar to one AG lifestyle cutpoint evaluated. CONCLUSION: Current findings indicate that the OM, NL, and W4L, ranging in price from $15 to $49, can provide reasonable estimates of free-living MVPA or activity time in comparison with a range of AG walking and lifestyle cutpoints.

A comparison of fitness training to a pedometer-based walking program matched for total energy cost.

BACKGROUND: Fitness and health variables were measured in 128 sedentary men and women randomly assigned to 6 months of fitness training (F), a walking program (W), or a control (C) group. METHODS: The F program gradually increased volume and intensity until 4 d/wk of training, at 70% of peak VO2 for 43 min/session was prescribed while the W group performed daily walking monitored with pedometers and increased until 10,000 steps x d-1 were prescribed. Total weekly energy expenditure was matched between the activity groups. The control group was asked to maintain their usual activity. RESULTS: Body mass, waist circumference, waist/hip ratio, resting HR were reduced in all groups after 6 months (P < .05). Fasting glucose, glucose tolerance, and total cholesterol were similarly improved in all groups (P < .05). Blood pressure and HR decreased during submaximal exercise in all groups (P < .05) but rating of perceived exertion (RPE) was decreased only in the F group (P < .05). Only the F participants showed a significant increase in ventilatory threshold (VT; ~15%) and peak VO2 (~9%) after 6 months. CONCLUSIONS: Supervised fitness training in previously sedentary adults produced greater improvements in submaximal RPE, BP(sys), VT, and peak VO2 but not other fitness and health-related variables compared with a pedometer-based walking program matched for total energy cost.

Effect of pretesting on intentions and behaviour: a pedometer and walking intervention.

This study addressed the influence of pedometers and a pretest on walking intentions and behaviour. Using a Solomon four-group design, 63 female university students were randomly assigned to one of four conditions: pedometer and pretest (n = 16), pedometer and no pretest (n = 16), no pedometer and pretest (n = 15), no pedometer and no pretest (n = 16). The pretest conditions included questions on walking, intentions to walk 12,500 steps per day, and self-efficacy for walking 12,500 steps per day. In the pedometer conditions a Yamax Digi-Walker SW-650 pedometer was worn for one week. All participants completed posttest questions. While significant pretest x pedometer interactions would have indicated the presence of pretest sensitisation, no such interactions were observed for either intention or self-reported walking. Wearing pedometers reduced intentions for future walking and coping self-efficacy. However, after controlling for pretest self-reported walking, pedometer use resulted in more self-reported walking. We conclude that wearing a pedometer increased self-reported walking behaviour but that a pretest did not differentially influence walking intentions, behaviour, or self-efficacy.

Assessment of the reliability of a custom built Nordic Ski Ergometer for cross-country skiing power test.

AIM: Despite the recent development of cross-country ski technique having led to an increase in the importance of upper body power, there is a substantial lack of specific equipment for upper body force and power evaluation. In order to achieve good reproducibility of the skiing motion, a new upper body ergometer has been developed in our lab and tested by elite cross-country skiers. In this study, the reliability of this device was assessed comparing upper body power measurements with double poling ski performance in the field. METHODS: The new apparatus consists of an electric motor acting as load and actively controlled by a personal computer on the basis of force and velocity data. Nine cross-country skiers (age: 21.7+/-3.12 years; body weight: 72.2+/-3.8 kg), competing at international level, performed a ski test on a 1.2 km long sprint track and a 50 s exercise on the Nordic Ski Ergometer. The velocity of the last section (180 m, slope 1.37%) of the track, performed using the double poling technique at maximal voluntary intensity, was related to the upper body power measured at the ergometer. RESULTS: Mean upper body power was 9.22+/-2.29 W kg(-1), while average velocity on the section considered was 6.66+/-0.67 m s(-1). A high correlation (R(2)=0.871) was found between upper body power and ski velocity. CONCLUSION: In addition to overcoming the main limitations that affect traditionally used equipment, the strong relationship between the parameters obtained with the new ergometer and ski velocity indicates their ability to assess athletes performance. The new apparatus could therefore be considered a ski specific testing equipment for cross-country skiers which is useful for reproducing upper body involvement in cross-country ski-ing in a laboratory setting.

Assessment of speed and position during human locomotion using nondifferential GPS.

PURPOSE: To validate a nondifferential global positioning system (GPS) to measure speed, displacement, and position during human locomotion. METHODS: Three healthy participants walked and ran over straight and curved courses for 59 and 34 trials, respectively. A nondifferential GPS receiver provided speed data by Doppler shift and change in GPS position over time, which were compared with actual speeds determined by chronometry. Displacement data from the GPS were compared with a surveyed 100-m section, and static positions were collected for 1 h and compared with the known geodetic point. RESULTS: GPS speed values on the straight course were closely correlated with actual speeds (Doppler shift: r = 0.9994, P < 0.001, Delta GPS position/time: r = 0.9984, P < 0.001). Actual speed errors were lowest using the Doppler shift method (90.8% of values within +/- 0.1 m x s(-1)). Speed was slightly underestimated on a curved path, though still highly correlated with actual speed (Doppler shift: r = 0.9985, P < 0.001, Delta GPS distance/time: r = 0.9973, P < 0.001). Distance measured by GPS was 100.46 +/- 0.49 m, and 86.5% of static points were within 1.5 m of the actual geodetic point (mean error: 1.08 +/- 0.34 m, range 0.69-2.10 m). CONCLUSIONS: Nondifferential GPS demonstrated a highly accurate estimation of speed across a wide range of human locomotion velocities using only the raw signal data with a minimal decrease in accuracy around bends. This high level of resolution was matched by accurate displacement and position data. Coupled with reduced size, cost, and ease of use, this method offers a valid alternative to differential GPS in the study of overground locomotion.

A low-cost instrumented spatial linkage accurately determines ASIS position during cycle ergometry.

The purpose of this study was to develop and evaluate an alternative method for determining the position of the anterior superior iliac spine (ASIS) during cycling. The approach used in this study employed an instrumented spatial linkage (ISL) system to determine the position of the ASIS in the parasagittal plane. A two-segment ISL constructed using aluminum segments, bearings, and digital encoders was tested statically against a calibration plate and dynamically against a video-based motion capture system. Four well-trained cyclists provided data at three pedaling rates. Statically, the ISL had a mean horizontal error of 0.03 +/- 0.21 mm and a mean vertical error of -0.13 +/- 0.59 mm. Compared with the video-based motion capture system, the agreement of the location of the ASIS had a mean error of 0.30 +/- 0.55 mm for the horizontal dimension and -0.27 +/- 0.60 mm for the vertical dimension. The ISL system is a cost-effective, accurate, and valid measure for two-dimensional kinematic data within a range of motion typical for cycling.

Accelerometer assessment of physical activity in children: an update.

Accelerometry is frequently used to assess physical activity in children. The number of articles in this area has increased dramatically in the last 10 years. The aim of this article is to provide a contemporary overview of accelerometry research in children. Specifically, the review addresses the choice of monitor, choice of epoch, when and for how long activity should be measured, the lack of consensus over how to define a complete day of activity data, issues of compliance, methods for the calibration of activity output, and the richness of data available from accelerometry.

Validity of the inexpensive Stepping Meter in counting steps in free living conditions: a pilot study.

OBJECTIVES: To evaluate if inexpensive Stepping Meters are valid in counting steps in adults in free living conditions. METHODS: For six days, 35 healthy volunteers wore a criterion Yamax Digiwalker and five Stepping Meters every day until all 973 pedometers had been tested. Steps were recorded daily, and the differences between counts from the Digiwalker and the Stepping Meter were expressed as a percentage of the valid value of the Digiwalker step counts. The criterion used to determine if a Stepping Meter was valid was a maximum deviation of 10% from the Digiwalker step counts. RESULTS: A total of 252 (25.9%) Stepping Meters met the criterion, whereas 74.1% made an overestimation or underestimation of more than 10%. In more than one third (36.6%) of the invalid Stepping Meters, the deviation was greater than 50%. Most (64.8%) of the invalid pedometers overestimated the actual steps taken. CONCLUSIONS: Inexpensive Stepping Meters cannot be used in community interventions as they will give participants the wrong message.

Physical activity measurement in persons with chronic and disabling conditions: methods, strategies, and issues.

Measuring the physical activity of persons with chronic and disabling conditions presents complexities related to measuring instruments, the intensity of the activity being measured, the population being measured, and individual behavior and health status. They often have limitations in mobility that do not preclude physical activity but contribute to the complexity of measuring it, such as slow or altered gait, inability to walk, and the need for assistive devices. This article reviews currently available ways to measure physical activity, describes strengths and weaknesses of various measures, and provides examples of complexities in measuring physical activity in people who move differently.

Devices for ambulatory and home monitoring of blood pressure, lipids, coagulation, and weight management, part 2.

PURPOSE: The equipment and methods used for ambulatory and home monitoring of blood pressure, lipids, coagulation, and weight management are discussed. SUMMARY: Over 100 million people in the United States have one or more chronic diseases, such as diabetes, hypertension, and asthma. With the goal to improve health while reducing costs and the overall health care burden, ambulatory and home monitoring by pharmacists and patients are receiving more attention. Ambulatory and home monitoring of blood pressure, cholesterol, coagulation, and weight management (including devices for assessing overweight and obese patients, heart rate monitors, and pedometers) are convenient for clinicians and patients. Such monitoring provides pharmacists with an opportunity to differentiate their practices. Studies suggest that patients who are involved in ambulatory and home monitoring take a more active role in their health and may have better adherence to a prescribed diet and medication regimens. Studies also show that ambulatory and home monitoring, if done correctly, provide clinicians with a large quantity of reliable readings for future therapeutic decisions. Devices are also a means for pharmacists to increase their provision of pharmacy services. Ambulatory monitoring is billable in many clinic settings, and the devices can be a profitable addition to prescription services. CONCLUSION: Many devices are available to assist patients and clinicians in monitoring blood pressure, lipids, coagulation, and weight management. Familiarity with the devices will help in their proper selection and use.

Comparison of cardiovascular responses between upright and recumbent cycle ergometers in healthy young volunteers performing low-intensity exercise: assessment of reliability of the oxygen uptake calculated by using the ACSM metabolic equation.

OBJECTIVES: To clarify (1) differences in cardiovascular response during low-intensity exercise in the upright versus the recumbent position, and (2) whether the oxygen uptake (V o 2 ) calculated by the American College of Sports Medicine (ACSM) metabolic equation reflects the actual V o 2 at low-intensity testing. DESIGN: Repeated-measures comparison study. SETTING: University research laboratory. PARTICIPANTS: Thirty-one healthy, young volunteers (age, 23+/-2y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Blood pressure, rate pressure product (RPP), V o 2 , oxygen pulse, carbon dioxide output (V co 2 ), and ventilatory equivalent (V e ) were measured during graded exercise testing using upright and recumbent cycle ergometers. The estimated V o 2 was calculated by using the ACSM metabolic equation. RESULTS: Systolic blood pressure, RPP, V o 2 , oxygen pulse, V co 2 , and V e at 15 or 30W were significantly higher in the recumbent position than in the upright one ( P <.05), however, no significant differences were observed at 50 and 70W. The estimated V o 2 during exercise was significantly higher than the actual one, at every level of intensity, from 15 to 70W ( P <.05). CONCLUSIONS: Cardiovascular responses should be carefully monitored even during low-intensity exercise using a recumbent cycle ergometer. The V o 2 estimated using the ACSM metabolic equation did not reflect the actual V o 2 during low-intensity exercise at 70W or less.

Description and validation of the ActiReg: a novel instrument to measure physical activity and energy expenditure.

The ActiReg (PreMed AS, Oslo, Norway) system is unique in using combined recordings of body position and motion alone or combined with heart rate (HR) to calculate energy expenditure (EE) and express physical activity (PA). The ActiReg has two pairs of position and motion sensors connected by cables to a battery-operated storage unit fixed to a waist belt. Each pair of sensors was attached by medical tape to the chest and to the front of the right thigh respectively. The collected data were transferred to a personal computer and processed by a dedicated program ActiCalc. Calculation models for EE with and without HR are presented. The models were based on literature values for the energy costs of different activities and therefore require no calibration experiments. The ActiReg system was validated against doubly labelled water (DLW) and indirect calorimetry. The DLW validation demonstrated that neither EE calculated from ActiReg data alone (EEAR) nor from combined ActiReg and HR data (EEAR-HR) were statistically different from DLW results. The EEAR procedure causes some underestimation of EE >11 MJ corresponding to a PA level >2.0. This underestimation is reduced by the EEAR-HR procedure. The objective recording of the time spent in different body positions and at different levels of PA may be useful in studies of PA in different groups and in studies of whether recommendations for PA are being met. The comparative ease of data collection and calculation should make ActiReg a useful instrument to measure habitual PA level and EE.

Total energy expenditure estimated using a foot-contact pedometer.

BACKGROUND: Total energy expenditure (TEE) assessment using pedometers provide an easy and less expensive method than doubly labeled water (DLW). This study assessed TEE by a new pedometry method (TEEpedo) compared to the doubly labeled water method (TEEdlw). MATERIAL/METHODS: Shipboard sailors (7 men, age: 23.0+/-3.9 yrs; ht: 180.2+/-6.5 cm; wt: 83.8+/-11.8 kg, and 10 women, age: 24.7+/-4.4 yrs; ht: 165.2+/-8.0 cm; wt: 63.5+/-14.0 kg) (Mean +/-SD) were studied for 8 days. The energy cost of activity was estimated using (a) total body weight, (b) foot-ground contact times [Tc] during running, walking, and non-exercise activity [NEAT], and (c) the known proportion of time spent in each activity category. Resting metabolic rate (RMR) was estimated from lean body mass. RESULTS: TEEPEDO was calculated as: TEEpedo (MJ) = (1440 x [%Run Time x ((0.0761 x [Total Body Weight/TcRun]) - 7.598) +%Walk Time x ((0.056 x [Total Body Weight/TcWalk]) - 2.938) + (%NEAT Time x 0.1 x [RMR/Minute])] + RMR)/239. This method, explained 79% of the variance of TEEpedo with a 95% confidence interval of +/-0.81 MJ/day, relative to TEEdlw (12.55+/-3.3MJ/day). Mean TEEpedo (12.65+/-3.1 MJ/day) did not differ from mean TEEdlw (p=0.95). CONCLUSIONS: At TEEs >14 MJ/day, the TEEpedo method underestimated actual TEE, possibly due to unaccounted for upper body exercise. At more moderate TEEs of 9 to 14 MJ/day, the Tc pedometry method provided accurate estimates of TEE.

[A method increasing G-tolerance of fighters' pilots with symptoms of the partial cardiovascular deficiency]. / Metod povysheniia ustoichivosti k peregruzkam letchikov istrebitel'noi aviatsii s iavleniiami partsial'noi nedostatochnosti serdechno-sosudistoi sistemy.

Training on the static ergometer was shown to increase tolerance of fighters' pilots for radial accelerations. Proposed is a program of training on the static ergometer consisting of two incremental loads in the interval between 120 and 240 kgf. In persons with cardiac pathologies this training program noticeably improved parameters of the cardiovascular adaptive reaction to static loads. Effectiveness, technical simplicity and low cost of the training are the attributes that can insure it a proper place in the rehabilitative treatment of pilots prior to or during the institutional examination as a part of the medical flight certification.

Energy cost of riding bicycles with shock absorption systems on a flat surface.

Bike shock absorption systems reduce the energy variation induced by terrain irregularities, leading to a greater comfort. However, they may also induce an increase in energy expenditure for the rider. More specifically, cross-country racers claim that rear shock absorption systems generate significant energy loss. The energy losses caused by such systems may be divided in terrain-induced or rider-induced. This study aims at evaluating the rider-induced energy loss of modern suspended bicycles riding on a flat surface. Twelve experienced competitive racers underwent three multistage gradational tests (50 to 250 W) on a cross-country bicycle mounted on an electromagnetically braked cycle ergometer. Three different tests were performed on a fully suspended bike, front suspended and non-suspended bicycle, respectively. The suspension mode has no significant effect on VO2. The relative difference of VO2 between the front-suspended or full-suspended bike and the rigid bike reaches a non significant maximum of only 3%. The claims of many competitors who still prefer front shock absorption systems could be related to a possible significant energy loss that could be present at powers superior to 250 W or when they stand on the pedals. It could also be generated by terrain-induced energy loss.