Validity and reliability of the Axiom PowerTrain cycle ergometer when compared with an SRM powermeter

The purpose of this study was to determine the validity and the reliability of a stationary electromagnetically-braked cycle ergometer (Axiom PowerTrain) against the SRM power measuring crankset. Nineteen male competitive cyclists completed four tests on their bicycle equipped with a 20-strain gauges SRM crankset: a maximal aerobic power (MAP) test and three 10-min time trials (TTs) with three different simulated slopes (0, 3, and 6 %). The Axiom ergometer overestimated (p <0.05) the SRM power output during the last stage of the MAP test and during TTs, by 5 % and 12 %, respectively. Power output (PO) of the Axiom ergometer drifted significantly (p <0.05) with the time during TT. These findings indicate that the Axiom ergometer does not provide a valid measure of PO compared with SRM. However, the small coefficient of variation (2.2 %) during the MAP test indicates that the Axiom provides a reliable PO and that it can be used e.g. for relative PO comparisons with competitive cyclists during a race season.     

Validity and reliability of the Polar S710 mobile cycling powermeter

The purpose of this study was to determine the validity and reliability of a new mobile bike-powermeter, Polar S710, in laboratory and field conditions, against the SRM crankset. Eight trained subjects performed in a random order six uphill cycling trials of 6-min duration at three different intensities (60 %, 75 % and 90 % of peak power output [PPO]). In addition, 44 other cyclists performed in the laboratory three cycling bouts each of 5-min duration at three different pedal cadences (60, 90 and 110 rpm) at the same absolute intensity (approximately 150 W). Bias between the two devices was correlated (r = 0.79) with the mean power in field conditions; with the S710 reading higher (p < 0.001) by 7.4 +/- 5.1 % than the SRM in the range of power studied. In other words, the mean differences between the two devices increased as the exercise intensity increased. The mean power output obtained with S710 was significantly higher (p < 0.001) by 6.8 +/- 7.9 W (bias x divided-by random error = 1.042 x divided-by 1.049) than the power obtained with SRM in laboratory conditions. Ninety-five percent of the differences of power measured with the S710 ranged between 21.4 W above to 8.3 W below the SRM in laboratory conditions. Mean differences between the two devices increased as the pedalling cadence increased (0.6 +/- 3.8 %, 4.4 +/- 3.7 % and 7.8 +/- 4.4 % at cadence of 60, 90 and 110 rpm respectively). Coefficients of variation in mean power across the four field-based trials at 75 % PPO was 2.2 % and 1.9 % for S710 and SRM, respectively. In conclusion, the S710 recorded power outputs higher than the SRM system in both field and laboratory conditions. Pedalling cadence and exercise intensity influenced differences in mean power. These characteristics make S710 a useful device for recreational cyclists but not for elite cyclists or scientists who require a greater accuracy and validity. However, the limits of the present study (short-term duration testing; single tested variables as intensity, posture, pedalling cadence) require further investigation for generalizing the present results to extensive use in "real world" cycling.     

Validity and reliability of the Ergomopro powermeter

The aim of this investigation was to assess the validity and reliability of the Ergomopro powermeter. Nine participants completed trials on a Monark ergometer fitted with Ergomopro and SRM powermeters simultaneously recording power output. Each participant completed multiple trials at power outputs ranging from 50 to 450 W. The work stages recorded were 60 s in duration and were repeated three times. Participants also completed a single trial on a cycle ergometer designed to assess bilateral contributions to work output (Lode Excaliber Sport PFM). The power output during the trials was significantly different between all three systems, (p < 0.01) 231.2 +/- 114.2 W, 233.0 +/- 112.4 W, 227.8 +/- 108.8 W for the Monark, SRM and Ergomopro system, respectively. When the bilateral contributions were factored into the analysis, there were no significant differences between the powermeters (p = 0.58). The reliability of the Ergomopro system (CV%) was 2.31 % (95 % CI 2.13 - 2.52 %) compared to 1.59 % (95 % CI 1.47 to 1.74 %) for the Monark, and 1.37 % (95 % CI 1.26 - 1.50 %) for the SRM powermeter. These results indicate that the Ergomopro system has acceptable accuracy under these conditions. However, based on the reliability data, the increased variability of the Ergomopro system and bilateral balance issues have to be considered when using this device.     

The validity of power output recorded during exercise performance tests using a Kingcycle air-braked cycle ergometer when compared with an SRM powermeter

This study assessed the validity of power output recorded using an air-braked cycle ergometer (Kingcycle) when compared with a power measuring crankset (SRM). For part one of the study thirteen physically active subjects completed a continuous incremental exercise test (OBLA), for part two of the study twelve trained cyclists completed two tests; a maximal aerobic power test (MAP) and a 16.1 km time-trial (16.1 km TT). The following were compared; the peak power output (PPO) recorded for 1 min during MAP, the average power output for the duration of the time-trial and power output recorded during each stage of OBLA. For all tests, power output recorded using Kingcycle was significantly higher than SRM (P < 0.001). Ratio limits of agreement between SRM and Kingcycle for OBLA showed a bias (P < 0.00) of 0.90 (95%CI = 0.90-0.91) with a random error of X or / 1.07, and for PPO and 16.1 km TT ratio limits of agreement were 0.90 (95%CI = 0.88-0.92) X or / 1.07 and 0.92 (95% CI = 0.90-0.94) X or / 1.07, respectively. These data revealed that the Kingcycle ergometry system did not provide a valid measure of power output when compared with SRM.     

Validity of cycle test in air compared to underwater cycling.

According to international guidelines, fitness to dive is generally assessed using a bicycle stress test (BST) in air. To date, there is no study explicitly addressing the question whether the results of a BST in air really predict performance status under water. Therefore, the aim of the present study was twofold: first, to design an experimental setting allowing the examination of physical performance status under water, and second, to examine whether there is an association of response to exercise in air compared to exercise under water using self contained underwater breathing apparatus (SCUBA). We constructed and evaluated a measurement technique for a bicycle ergometry and for gas analysis under water. Part of the work was the development of a new valve system which allowed to collect the exhaled air in total and to transport it to the spirometer next to the pool. Twenty-eight healthy male divers underwent a BST. Compared to a given workload in air, gross capacity decreased significantly by about 50% underwater. High performance in air was associated with a high performance underwater. The examinations were carried out without any complications. In conclusion, our experimental setting allowed the safe and reliable examination of physical performance status under water. First results indicate that the results of a BST in air correlate well with the cardio-circulatory performance status underwater. A subsequent study with a larger sample size will enable us to more precisely model this correlation.     

Further mechanical considerations between polar and SRM mobile ergometer systems during laboratory-based high-intensity, intermittent cycling activity

The purpose of this article is to outline mechanical issues related to the use of the Polar S710 heart monitor with Power Unit when compared with the SRM Powercrank system. There are issues outlined in this article that refer to the suitability of the Polar S710 for the quantification of performance during downhill cycling that relate to chain vibration, chain tension, and time interval sampling rates.     

Validity and reliability of the SPORTS score

Purpose  

Successful outcomes for an athlete usually consist of returning to their sport. The Subjective Patient Outcome for Return to Sports (SPORTS) score has been recently proposed as an easy to use score for evaluating an athlete’s ability to return to their sport. The aim of this study was to test the reliability and validity of the SPORTS score in athletes 5–10 years after anterior cruciate ligament reconstruction.     

Contoured in-shoe foot orthoses increase mid-foot plantar contact area when compared with a flat insert during cycling

ObjectivesTo determine the effect of contouring of an in-shoe foot orthosis on plantar contact area and surface pressure, as well as perceived comfort and support at the foot-orthosis interface during stationary cycling.DesignA randomised, repeated measures control study.MethodsTwelve cyclists performed steady-state seated cycling at a cadence of 90 rpm using a contoured orthosis and a flat insert of similar hardness. Contact area (CA) and plantar mean pressure (PP) were measured using the PEDAR^® system, determined for seven discrete plantar regions and represented as the percentage of the total CA and PP respectively (CA% and PP%). Perceived comfort and support were rated using a visual analogue scale (VAS).ResultsThe contoured orthosis produced a significantly greater CA% at the medial midfoot (p = 0.001) and lateral midfoot (p = 0.009) with a standardised mean difference (SMD) of 1.3 and 0.9 respectively. The contoured orthosis also produced a significantly greater PP% at the hallux (p = 0.003) compared to the flat insert with a SMD of 1.1. There was a small non-significant effect (SMD < 0.4) for the perceived comfort measures between conditions, but perceived support was significantly greater at the arch (p = 0.000) and heel (p = 0.013) with the contoured orthoses (SMD of 1.5 and 0.9, respectively).ConclusionsContoured orthoses influenced the plantar surface of the foot by increasing contact area as well as a perception of greater support at the midfoot while increasing relative pressure through the hallux when compared to a flat insert during stationary cycling. No difference in perceived comfort was noted.     

The reliability of cycling efficiency

PURPOSE: The aim of this experiment was to establish the reproducibility of gross efficiency (GE), delta efficiency (DE), and economy (EC) during a graded cycle ergometer test in seventeen male subjects. METHODS: All subjects performed three identical exercise tests at a constant pedal cadence of 80 rpm on an electrically braked cycle ergometer. Energy expenditure was estimated from measures of oxygen uptake (VO(2)) and carbon dioxide production (VCO(2)) by using stoichiometric equations. RESULTS: The subjects characteristics were age 24 +/- 6 yr, body mass 74.6 +/- 6.9 kg, body fat 13.9 +/- 2.2%, and VO(2max) 61.9 +/- 2.4 mL x kg(-1) x min(-1) (all means +/- SD). Average GE, DE, and EC for the three tests were 19.8 +/- 0.6%, 25.8 +/- 1.5%, and 5.0 +/- 0.1 kJ x L(-1), respectively. The coefficients of variation (confidence limits) were GE 4.2 (3.2-6.4)%, DE 6.7 (5.0-10.0)%, and EC 3.3 (2.4-4.9)%. GE was significantly lower at 95 W and 130 W when compared with 165 W, 200 W, 235 W, 270 W, and 305 W. GE at 165 W was significantly lower (P < 0.05) that GE at 235 W. A weak correlation (r = 0.491; P < 0.05) was found between peak oxygen uptake (VO(2peak)) and GE, whereas no correlations were found between VO(2max) and DE or EC. CONCLUSION: We conclude that a graded exercise test with 3-min stages and 35-W increments is a method by which reproducible measurements of both GE and EC can be obtained, whereas measurements of DE seemed slightly more variable.     

Validity and reliability of the myTemp ingestible temperature capsule

Objectives

An accurate and non-invasive measurement of core body temperature (Tc) is of great importance to quantify exercise-induced increases in Tc in athletes or to assess changes in Tc in patient populations. The use of ingestible gastrointestinal telemetric temperature capsules is widely accepted as a surrogate marker for Tc, but widespread implementation is lacking due to the high costs of these disposable capsules. A new and cheaper temperature capsule system (i.e. myTemp) was recently introduced. The aim of present study is to determine the validity and test–retest reliability of the myTemp system.

Validity and test-retest reliability of the Stride Analyzer in people with knee osteoarthritis

IntroductionSubjects with knee osteoarthritis walk differently compared to healthy subjects. Managing these gait alterations has been proven effective for reducing pain and increasing function. The Stride Analyzer is a low cost gait analysis tool but its clinimetric properties have not been investigated yet in subjects with symptomatic knee osteoarthritis. The aim of this study was to investigate the reliability and validity of the SA compared with the Gold standard (Vicon) in persons with knee OA.MethodsFifteen subjects with symptomatic knee osteoarthritis were instructed to walk at a self-selected speed in a gait laboratory. Temporospatial (TS) gait parameters were recorded simultaneously by the Stride Analyzer and by a 16-camera-infrared optoelectronic motion capturing system (Vicon). Validity and test-retest reliability of the Stride Analyzer were examined by Bland-Altman plots, intra-class correlation coefficients (ICC) and the standard error of measurement (SEM).ResultsTest-retest analyses showed good agreement for all TS parameters with ICC values ranging from 0.805 (single limb support right) to 0.949 (velocity) and SEM% values ranging from 0.78% (stance phase right (% of gait cycle)) to 4.52% (double limb support right (% of gait cycle)). Good agreement between Stride Analyzer and Vicon was found for the following TS parameters: velocity (z = 1.01), cadence (z = −0.85), stride length (z = 1.63) and gait cycle (z = 0.86). All other gait parameters showed lower ICC values (<0.689).InterpretationOur results suggest that the Stride Analyzer can be used in the clinical field to perform gait analysis in subjects with symptomatic knee osteoarthritis.     

Validity and reliability of the Dynamic Gait Index in children with hemiplegic cerebral palsy

BackgroundDynamic Gait Index (DGI) is a performance-based tool can be applied in a short time and evaluates dynamic balance and gait ability.Research questionIs the DGI valid and reliable for assessing gait and balance disorders in children with hemiplegic cerebral palsy (CP)?MethodsSixteen children with hemiplegic CP (5 females, 11 males; mean age 10y 3mo, SD 2y 7mo; range 6–14y; Gross Motor Function Classification System (GMFCS) levels I [n = 9], II [n = 7]) and 16 age-matched typically developing (TD) (8 females, 8 males; mean age 9y 9mo, SD 2y 6mo; range 6–14y) participated. The relationship between the DGI, Four-Square Step Test (FSST), Timed Up and Go Test (TUG) and Pediatric Berg Balance Scale (PBS) was analyzed. To determine the test-retest reliability, the DGI was performed twice and; for the inter-rater reliability, only DGI was reapplied by a different rater on the same day. Internal consistency was obtained by Cronbach-α value. Validity was tested by Spearman correlation coefficient and reliability was calculated by Intraclass correlation coefficient (ICC).ResultsThere was a significant difference between hemiplegic CP and TD and between the children with GMFCS level I and II in the comparison of results of the DGI and other tests. All items on the DGI had appropriate internal consistency (Cronbach-α = 0.969). The test-retest (ICC = 0.970 CI(0.915- 0.990)) and inter-rater (ICC = 0.983 CI(0.882- 0.998)) reliabilities were found to be excellent. A negative, moderate correlation between FSST and DGI (rs = −0.673, p = 0.004); a positive, high correlation between PBS (rs = 0.724, p = 0.002) and DGI and a negative, high correlation between TUG and DGI (rs = −0.828, p < 0.001) was detected.SignificanceDGI with features such as its feasibility in a short time, being simple but distinctive and not requiring heavy equipment is a valid and reliable method in children with hemiplegic CP.     

Validity and reliability of the Fels physical activity questionnaire for children

PURPOSE: The aim was to evaluate the reliability and validity of the Fels physical activity questionnaire (PAQ) for children 7-19 yr of age. METHODS: A cross-sectional study was conducted among 130 girls and 99 boys in elementary (N=70), middle (N=81), and high (N=78) schools in rural Maryland. Weight and height were measured on the initial school visit. All the children then wore an Actiwatch accelerometer for 6 d. The Fels PAQ for children was given on two separate occasions to evaluate reliability and was compared with accelerometry data to evaluate validity. RESULTS: The reliability of the Fels PAQ for the girls, boys, and the elementary, middle, and high school age groups range was r=0.48-0.76. For the elementary school children, the correlation coefficient examining validity between the Fels PAQ total score and Actiwatch (counts per minute) was 0.34 (P=0.004). The correlation coefficients were lower in middle school (r=0.11, P=0.31) and high school (r=0.21, P=0.006) adolescents. The sport index of the Fels PAQ for children had the highest validity in the high school participants (r=0.34, P=0.002). CONCLUSION: The Fels PAQ for children is moderately reliable for all age groups of children. Validity of the Fels PAQ for children is acceptable for elementary and high school students when the total activity score or the sport index is used. The sport index was similar to the total score for elementary students but was a better measure of physical activity among high school students.     

Validity and reliability of shuttle-run test in Korean adults

The purpose of this study was to evaluate equations of Leger (E1, 1988) and Brewer (E2, 1988) to predict VO (2max) in Korean adults (158 men and 155 women), and reliability tests were randomly conducted among men ( N=90) and women (n=29) in addition to VO (2max) measurements during a graded exercise treadmill test. Both equations significantly underestimated VO (2max) compared to those from the treadmill test ( P<0.01). A strong intra-class correlation between the treadmill result and 20 m shuttle run test was detected (0.86-0.94, P<0.001). 95 percentile limit of agreement of absolute difference in E1 and E2 in both genders were mostly larger than results from the treadmill test. There was a strong correlation between laboratory test and retest but testing hypothesis of equality of means in men showed significant bias ( P=0.003), except difference between test and retest in women ( P=0.05). The test and retest of the upper and lower of absolute difference ± 95% limit of agreement were -4.86 to -19.05 (men) and 13.61 to 27.91 (women). In conclusion, their equations, based on the results, should not be applied for predicting VO (2max) in Korean adults.     

Validity and reliability of an iPad with a three-dimensional camera for posture imaging

BackgroundIt is important to quantify a static posture to evaluate the need for and effectiveness of interventions such as physical management, physiotherapy, spinal orthosis or surgical treatment on the alignment of body segments. Motion analysis systems can be used for this purpose, but they are expensive, require a high degree of technical experience and are not easily accessible. A simpler method is needed to quantify static posture. Research objective: Assess validity and inter and intra rater reliability using an iPad with a 3-D camera to evaluate posture and postural deformity.MethodA 3-D model of a lying posture, created using an iPad with a 3-D camera, was compared to a Qualisys motion analysis system of the same lying posture, the latter used as the gold standard. Markers on the trunk and the leg were captured by both systems, and results from distance and angle measurements were compared.ResultsAll intra-class correlation coefficient values were above 0.98, the highest systematic error was 4.3 mm for length measurements and 0.2° for angle measurements. Significance: A 3-D model of a person, with markers on anatomical landmarks, created with an iPad with a 3-D camera, is a valid and reliable method of quantifying static posture.ConclusionAn iPad with a 3-D camera is a relatively inexpensive, valid and reliable method to quantify static posture in a clinical environment.     

Validity, reliability and sensitivity of measures of sporting performance

Performance testing is one of the most common and important measures used in sports science and physiology. Performance tests allow for a controlled simulation of sports and exercise performance for research or applied science purposes. There are three factors that contribute to a good performance test: (i) validity; (ii) reliability; and (iii) sensitivity. A valid protocol is one that resembles the performance that is being simulated as closely as possible. When investigating race-type events, the two most common protocols are time to exhaustion and time trials. Time trials have greater validity than time to exhaustion because they provide a good physiological simulation of actual performance and correlate with actual performance. Sports such as soccer are more difficult to simulate. While shuttle-running protocols such as the Loughborough Intermittent Shuttle Test may simulate physiology of soccer using time to exhaustion or distance covered, it is not a valid measure of soccer performance. There is a need to include measures of skill in such protocols. Reliability is the variation of a protocol. Research has shown that time-to-exhaustion protocols have a coefficient of variation (CV) of >10%, whereas time trials are more reliable as they have been shown to have a CV of <5%. A sensitive protocol is one that is able to detect small, but important, changes in performance. The difference between finishing first and second in a sporting event is <1%. Therefore, it is important to be able to detect small changes with performance protocols. A quantitative value of sensitivity may be accomplished through the signal : noise ratio, where the signal is the percentage improvement in performance and the noise is the CV.     

Validity and reliability of cardiac output by CO2 rebreathing

This article reviews the available literature on the validity and reliability of the non-invasive techniques, commonly known as CO2 rebreathing, for estimating cardiac output. The differing indirect methodologies are described and illustrated. A table, constructed from the available literature, comparing criterion versus estimated cardiac outputs is presented. The varying combinations of methods employed, differing measurement conditions, i.e. rest and exercise, and divergent populations are illustrated and discussed. The correlation between criterion and estimated cardiac output for these studies ranged from r = 0.09 to 0.96, with a % standard deviation of the differences of 1.5 to 176.8%. The Collier and end-tidal methods, in conjunction with either the Comroe or McHardy CO2 dissociation curve appears to be the most established, valid and reliable combination of methods for estimating resting cardiac output. These methods appear to be comparable to the combination of the Defares, end-tidal and Comroe curve methods for estimating cardiac output during exercise. Because of the potential for large errors, caution is urged when interpreting cardiac output results based on indirect estimation for individual assessment, or for subjects with certain types of pulmonary or heart diseases.     

Validity and reliability of selected commercially available metabolic analyzer systems

Automated metabolic gas analysis systems have advanced considerably over the past decade. They provide an abundance of information, which is not possible by using the traditional Douglas bag method and have become an essential tool in both physiological monitoring and in the diagnosis of cardiopulmonary disease. The validity and reliability of the different online metabolic analyzer systems are not well known, with relatively few independent studies being published. The purpose of this review was to examine and evaluate current literature regarding the validity and reliability of commercially available metabolic analyzer systems. This review reveals significant differences between the available systems in the way that they capture and process basic respiratory measurements. Online metabolic analyzer systems were found to vary significantly when compared with Douglas bag methods. These variations have the potential to introduce error into the accuracy with which the health of cardiovascular system can be assessed or training loads can be assigned. Compounding this is the fact that many automated systems are a "black box", which makes it easy to generate data without the user having much understanding of how the data were generated. In conclusion automated metabolic analyser systems are a scientifically robust method for the evaluation of cardiopulmonary function. Individual researchers and clinicians must, however, be able to make their own decisions about the level of error that is tolerable for their individual needs. This presents a significant practical challenge in light of the speed with which technical developments in the field occur and we make some suggestions for the formulation of intersystem comparison studies.