Wrist-worn accelerometers are emerging as the most common instrument for measuring physical activity in large-scale epidemiological studies, though little is known about the relationship between ...wrist acceleration and physical activity energy expenditure (PAEE).
1695 UK adults wore two devices simultaneously for six days; a combined sensor and a wrist accelerometer. The combined sensor measured heart rate and trunk acceleration, which was combined with a treadmill test to yield a signal of individually-calibrated PAEE. Multi-level regression models were used to characterise the relationship between the two time-series, and their estimations were evaluated in an independent holdout sample. Finally, the relationship between PAEE and BMI was described separately for each source of PAEE estimate (wrist acceleration models and combined-sensing).
Wrist acceleration explained 44-47% between-individual variance in PAEE, with RMSE between 34-39 J•min-1•kg-1. Estimations agreed well with PAEE in cross-validation (mean bias 95% limits of agreement: 0.07 -70.6:70.7) but overestimated in women by 3% and underestimated in men by 4%. Estimation error was inversely related to age (-2.3 J•min-1•kg-1 per 10y) and BMI (-0.3 J•min-1•kg-1 per kg/m2). Associations with BMI were similar for all PAEE estimates (approximately -0.08 kg/m2 per J•min-1•kg-1).
A strong relationship exists between wrist acceleration and PAEE in free-living adults, such that irrespective of the objective method of PAEE assessment, a strong inverse association between PAEE and BMI was observed.
Maximal oxygen consumption (VOsub.2max) is an important health indicator that is often estimated using a multiple regression model (MRM) or linear extrapolation method (LEM) with the heart rate (HR) ...during a step test. Nonetheless, both methods have inherent problems. This study investigated a VOsub.2max estimation method that mitigates the weaknesses of these two methods. A total of 128 adults completed anthropometric measurements, a physical activity questionnaire, a step test with HR measurements, and a VOsub.2max treadmill test. The MRM included step-test HR, age, sex, body mass index, and questionnaire scores, whereas the LEM included step-test HR, predetermined constant VOsub.2 values, and age-predicted maximal HR. Systematic differences between estimated and measured VOsub.2max values were detected using Bland-Altman plots. The standard errors of the estimates of the MRM and LEM were 4.15 and 5.08 mL·kgsup.−1·minsup.−1, respectively. The range of 95% limits of agreement for the LEM was wider than that for the MRM. Fixed biases were not significant for both methods, and a significant proportional bias was observed only in the MRM. MRM bias was eliminated using the LEM application when the MRM-estimated VOsub.2max was ≥45 mL·kgsup.−1·minsup.−1. In conclusion, substantial proportional bias in the MRM may be mitigated using the LEM within a limited range.
To determine the validity of the lactate threshold (LT) and maximal oxygen uptake (VO2max) determined during graded exercise test (GXT) of different durations and using different LT calculations. ...Trained male cyclists (n = 17) completed five GXTs of varying stage length (1, 3, 4, 7 and 10 min) to establish the LT, and a series of 30-min constant power bouts to establish the maximal lactate steady state (MLSS). VO2 was assessed during each GXT and a subsequent verification exhaustive bout (VEB), and 14 different LTs were calculated from four of the GXTs (3, 4, 7 and 10 min)-yielding a total 56 LTs. Agreement was assessed between the highest VO2 measured during each GXT (VO2peak) as well as between each LT and MLSS. VO2peak and LT data were analysed using mean difference (MD) and intraclass correlation (ICC). The VO2peak value from GXT.sub.1 was 61.0 #177; 5.3 mL.sup.. kg.sup.-1. min.sup.-1 and the peak power 420 #177; 55 W (mean #177; SD). The power at the MLSS was 264 #177; 39 W. VO2peak from GXT.sub.3, 4, 7, 10 underestimated VO2peak by ~1-5 mL.sup.. kg.sup.-1. min.sup.-1 . Many of the traditional LT methods were not valid and a newly developed Modified D.sub.max method derived from GXT.sub.4 provided the most valid estimate of the MLSS (MD = 1.1 W; ICC = 0.96). The data highlight how GXT protocol design and data analysis influence the determination of both VO2peak and LT. It is also apparent that VO2max and LT cannot be determined in a single GXT, even with the inclusion of a VEB.
To describe different end criteria for reaching maximal oxygen uptake (VO2max) during a continuous graded exercise test on the treadmill, and to explore the manner by which different end criteria ...have an impact on the magnitude of the VO2max result.
A sample of 861 individuals (390 women) aged 20-85 years performed an exercise test on a treadmill until exhaustion. Gas exchange, heart rate, blood lactate concentration and Borg Scale6-20 rating were measured, and the impact of different end criteria on VO2max was studied;VO2 leveling off, maximal heart rate (HRmax), different levels of respiratory exchange ratio (RER), and postexercise blood lactate concentration.
Eight hundred and four healthy participants (93%) fulfilled the exercise test until voluntary exhaustion. There were no sex-related differences in HRmax, RER, or Borg Scale rating, whereas blood lactate concentration was 18% lower in women (P<0.001). Forty-two percent of the participants achieved a plateau in VO2; these individuals had 5% higher ventilation (P = 0.033), 4% higher RER (P<0.001), and 5% higher blood lactate concentration (P = 0.047) compared with participants who did not reach a VO2 plateau. When using RER ≥1.15 or blood lactate concentration ≥8.0 mmol•L(-1), VO2max was 4% (P = 0.012) and 10% greater (P<0.001), respectively. A blood lactate concentration ≥8.0 mmol•L(-1) excluded 63% of the participants in the 50-85-year-old cohort.
A range of typical end criteria are presented in a random sample of subjects aged 20-85 years. The choice of end criteria will have an impact on the number of the participants as well as the VO2max outcome. Suggestions for new recommendations are given.
This study aimed to investigate the test–retest reliability, mean, and individual responses in the measurement of maximal oxygen consumption (V˙Osub.2max) during a cardiopulmonary exercise test ...(CPET) and the verification phase during cycle ergometry in women. Nine women (22 ± 2 yrs, 166.0 ± 4.5 cm, 58.6 ± 7.7 kg) completed a CPET, passively rested for 5 min, and then completed a verification phase at 90% of peak power output to determine the highest V˙Osub.2 from the CPET (V˙Osub.2CPET) and verification phase (V˙Osub.2verification) on 2 separate days. Analyses included a two-way repeated measures ANOVA, intraclass correlation coefficients (ICCsub.2,1), standard errors of the measurement (SEM), minimal differences (MD), and coefficients of variation (CoV). There was no test (test 1 versus test 2) × method (CPET vs. verification phase) interaction (p = 0.896) and no main effect for method (p = 0.459). However, test 1 (39.2 mL·kgsup.−1·minsup.−1) was significantly higher than test 2 (38.3 mL·kgsup.−1·minsup.−1) (p = 0.043). The V˙Osub.2CPET (ICC = 0.984; CoV = 1.98%; SEM = 0.77 mL·kgsup.−1·minsup.−1; MD = 2.14 mL·kgsup.−1·minsup.−1) and V˙Osub.2verification (ICC = 0.964; CoV = 3.30%; SEM = 1.27 mL·kgsup.−1·minsup.−1; MD = 3.52 mL·kgsup.−1·minsup.−1) demonstrated “excellent” reliability. Two subjects demonstrated a test 1 V˙Osub.2CPET that exceeded the test 2 V˙Osub.2CPET, and one subject demonstrated a test 1 V˙Osub.2verification that exceeded the test 2 V˙Osub.2verification by more than the respective CPET and verification phase MD. One subject demonstrated a V˙Osub.2CPET that exceeded the V˙Osub.2verification, and one subject demonstrated a V˙Osub.2verification that exceeded the V˙Osub.2CPET by more than the MD. These results demonstrate the importance of examining the individual responses in the measurement of the V˙Osub.2max and suggest that the MD may be a useful threshold to quantify real individual changes in V˙Osub.2.
Previous studies on handrim wheelchair-specific (an)aerobic exercise capacity in wheelchair athletes have used a diversity of participants, equipment, and protocols. Therefore, test results are ...difficult to compare among studies. The first aim of this scoping review is to provide an overview of the populations studied, the equipment and protocols used, and the reported outcomes from all laboratory-based studies on wheelchair-specific exercise capacity in wheelchair athletes. The second aim is to synthesize these findings into a standardized, yet individualized protocol. A scoping literature search resulted in 10 anaerobic and 38 aerobic protocols. A large variety in equipment, protocol design, and reported outcomes was found. Studies that systematically investigated the influence of protocol features are lacking, which makes it difficult to interpret and compare test outcomes among the heterogeneous group of wheelchair athletes. Protocol design was often dependent on a priori participant knowledge. However, specific guidelines for individualization were missing. However, the common protocol features of the different studies were united into guidelines that could be followed when performing standardized and individualized wheelchair-specific exercise capacity tests in wheelchair athletes. Together with guidelines regarding reporting of participant characteristics, used equipment, and outcome measures, we hope to work toward more international agreement in future testing.
Objective:The 6-minute walk test (6MWT) is an established measure of exercise capacity in adults and children with chronic cardiac or respiratory disease. Despite its widespread use, there are no ...normal values for healthy children under 12 years of age. We aimed to provide normal values for children between 4 and 11 years.Methods:Healthy children were recruited prospectively from two UK primary schools and also children visiting Great Ormond Street Hospital. 328 children (54% male) aged 4 to 11 years were included in the study. Main outcome measures were the distance walked in 6 minutes, and oxygen saturation and heart rate during the 6 minutes and during a 3-minute recovery period.Results:Mean oxygen saturation at baseline and during the 6MWT was 97–99%. Heart rate increased from 102±19 bpm at baseline to a maximum of 136±12 bpm. Overall, the mean distance walked in 6 minutes was 470±59 m. Distance walked correlated with age (r = 0.64, p<0.0001), weight (r = 0.51, p<0.0001) and height (r = 0.65, p<0.0001) with no significant difference between boys and girls. The distance walked increased significantly year on year from 4 to 7 years (4 years 383±41 m; 5 years 420±39 m, 6 years 463±40 m; 7 years 488±35 m; p<0.05 between each); further modest increases were observed beyond 7 years of age.Conclusions:Performing a 6MWT is feasible and practical in young children. This study provides data on normal children against which the performance of sick children and the response to therapeutic intervention can be judged.
Abstract
Background
Although the Fitkids Treadmill Test (FTT) has been validated and normative values are available for healthy 6- to 18-year-old children and adolescents, these facts do not ...automatically imply uptake of the test in routine practice of physical therapists.
Objective
The objectives of this study were to evaluate the utility of the FTT in different diagnostic groups and to explore potential factors affecting the use of the FTT in clinical practice.
Design
Mixed methods with both quantitative and qualitative data were used in this study.
Methods
Outcome parameters from the FTT were retrieved from the Fitkids database. For evaluation of the utility of the FTT, 2 indicators, exercise duration and maximal effort, were used. An online survey was sent to physical therapists in Fitkids practices to identify factors affecting the use of the FTT in clinical practice.
Results
The proportion of children and adolescents in each of the diagnostic groups who reached the minimal duration of a maximal exercise test ranged from 94% to 100%. The proportion of participants who reached a peak heart rate ≥180 beats/min ranged from 46% for participants with cognitive, psychological, or sensory disorders to 92% for participants with metabolic diseases. The most important facilitator for use of the FTT was the fact that most physical therapists were convinced of the additional value of the FTT. The main barriers were therapists’ attitudes (resistance to change/lack of experience) and, on the environmental level, the absence of a treadmill ergometer in physical therapist practice.
Limitations
Structured interviews would have provided more information on potential factors affecting the use of the FTT in clinical practice.
Conclusions
This study has shown the clinical utility of the FTT in different diagnostic groups in pediatric physical therapist practice. Responding to the factors identified in this study should enable improved uptake of the FTT in clinical practice.
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