Typical error versus limits of agreement

Discussion on the validity of commonly used reliability indices in sports medicine and exercise science: a critical review with data simulations

Apart from objectivity and validity, reliability is considered a precondition for testing within scientific works, as unreliable testing protocols limit conclusions, especially for practical application. Classification guidelines commonly refer to relative reliability, focusing on Pearson correlation coefficients (rp) and intraclass correlation coefficients (ICC). On those, the standard error of measurement (SEM) and the minimal detectable change (MDC) are often calculated in addition to the variability coefficient (CV). These, however, do not account for systematic or random errors (e.g., standardization problems). To illustrate, we applied common reliability statistics in sports science on simulated data which extended the sample size of two original counter-movement-jump sessions from (youth) elite basketball players. These show that excellent rp and ICC (≥ 0.9) without a systematic bias were accompanied by a mean absolute percentage error of over 20%. Furthermore, we showed that the ICC does not account for systematic errors and has only limited value for accuracy, which can cause misleading conclusions of data. While a simple re-organization of data caused an improvement in relative reliability and reduced limits of agreement meaningfully, systematic errors occurred. This example underlines the lack of validity and objectivity of commonly used ICC-based reliability statistics (SEM, MDC) to quantify the primary and secondary variance sources. After revealing several caveats in the literature (e.g., neglecting of the systematic and random error or not distinguishing between protocol and device reliability), we suggest a methodological approach to provide reliable data collections as a precondition for valid conclusions by, e.g., recommending pre-set acceptable measurement errors.

Higher Levels of Morning and Daytime Light Exposure Associated with Positive Sleep Indices in Professional Team Sport Athletes

Objective

Light exposure techniques have been recommended to combat sleep issues caused by disruption to circadian regularity in the athletic population, although studies are lacking.

Methods

A total of 17 professional male Australian Football athletes (age ± SD: 22 ± 3 years) wore a wrist actigraph to measure sleep parameters, and a wearable light sensor to measure melanopic equivalent daylight illuminance (mEDI, in lux) for 14 days. Participants completed three sleep questionnaires at the end of the data collection period and completed well-being surveys 6 times. The Sleep Regularity Index (SRI) for each player was also calculated from actigraphy data. Light exposure data were organised into three different timeframes: morning (wake time + 2 hours), daytime (end of morning to 6 pm), and evening (2 hours leading up to bedtime) for analysis. Repeated measures correlation was conducted for objective sleep measures and mEDI values per timeframe. Pearson's correlation was conducted on subjective sleep measures and well-being measures against mEDI values per timeframe.

Results

Higher morning light was associated with significantly (p < 0.001) greater total sleep time (r = 0.31). Higher daytime light exposure was associated with higher subjective sleep quality (r = 0.48, p < 0.05). Higher evening light exposure was associated with higher Athlete Sleep Screening Questionnaire (ASSQ) global scores (r = 0.52, p < 0.05). There were no other significant correlations between light exposure and sleep or well-being measures (p > 0.05).

Conclusion

Higher morning and daylight exposure levels were associated with various positive objective and subjective sleep measures in professional team sport athletes, supporting the need for education on optimising light exposure to improve circadian function, sleep, and health.

The test-retest reliability of physiological and perceptual responses during treadmill load carriage

PURPOSE

Understanding the test-retest reliability of physiological responses to load carriage influences the interpretation of those results. The aim of this study was to determine the test-retest reliability of physiological measures during loaded treadmill walking at 5.5 km h-1 using the MetaMax 3B.

METHODS

Fifteen Australian Army soldiers (9 male, 6 female) repeated two 12-min bouts of treadmill walking at 5.5 km h-1 in both a 7.2 kg Control condition (MetaMax 3B, replica rifle) and a 23.2 kg Patrol condition (Control condition plus vest) across three sessions, separated by one week. Expired respiratory gases and heart rate were continuously collected, with the final 3 min of data analysed. Ratings of Perceived Exertion and Omnibus-Resistance Exercise Scale were taken following each trial. Reliability was quantified by coefficient of variation (CV), intra-class correlation coefficients (ICC), smallest worthwhile change (SWC), and standard error of the measurement.

RESULTS

Metabolic and cardiovascular variables were highly reliable (≤ 5% CV; excellent-moderate ICC), while the respiratory variables demonstrated moderate reliability (< 8% CV; good-moderate ICC) across both conditions. Perceptual ratings had poorer reliability during the Control condition (12-45% CV; poor ICC) than the Patrol condition (7-16% CV; good ICC).

CONCLUSIONS

The test-retest reliability of metabolic and cardiovascular variables was high and relatively consistent during load carriage. Respiratory responses demonstrated moderate test-retest reliability; however, as the SWC differed with load carriage tasks, such data should be interpreted independently across loads. Perceptual measures demonstrated poor to moderate reliability during load carriage, and it is recommended that they only be employed as secondary measures.

Test-Retest Reliability, Criterion-Related Validity, and Ecological Validity of the Test of Visual-Motor Skills, Third Edition, in Kindergarten Children With Developmental Coordination Disorder

IMPORTANCE

Establishing empirical evidence on the psychometric properties of the Test of Visual-Motor Skills (3rd ed.; TVMS-3) is helpful for guiding its use as an assessment of visual-motor integration (VMI) skills in kindergarten children with developmental coordination disorder (DCD).

OBJECTIVE

To investigate the test-retest reliability, criterion-related validity, and ecological validity of the TVMS-3 in Taiwanese kindergarten children with DCD.

DESIGN

A nonexperimental, descriptive, correlational design.

SETTING

A hospital in Central Taiwan.

PARTICIPANTS

Fifty-seven kindergarten children with DCD were recruited in the study.

OUTCOMES AND MEASURES

Intraclass correlation coefficient, percentage of minimal detectable change, and paired t test (Wilcoxon signed rank test) were used to investigate the test-retest reliability of the TVMS-3. The correlations (Pearson's r) between the TVMS-3 accuracy score and the scores of each of the four domains and the adaptive behavior composite score of the Vineland Adaptive Behavior Scales (3rd ed.; Vineland-3) were calculated, respectively, to examine criterion-related validity and ecological validity.

RESULTS

The accuracy score of the TVMS-3 had excellent test-retest reliability and acceptable random measurement error. Moreover, it showed good criterion-related validity and sufficient ecological validity with the Vineland-3 in Taiwanese kindergarten children with DCD.

CONCLUSIONS AND RELEVANCE

The accuracy score of the TVMS-3 is applicable to Taiwanese kindergarten children with DCD in clinical and research settings. Plain-Language Summary: The accuracy score of the Test of Visual-Motor Skills (3rd ed.; TVMS-3) is a useful assessment tool to detect deficits in visual-motor integration for Taiwanese kindergarten children with developmental coordination disorder. The TVMS-3 has excellent test-retest reliability, good criterion-related validity, and sufficient ecological validity.

Validity and reliability of self-reported and neural measures of listening effort

Listening effort can be defined as a measure of cognitive resources used by listeners to perform a listening task. Various methods have been proposed to measure this effort, yet their reliability remains unestablished, a crucial step before their application in research or clinical settings. This study encompassed 32 participants undertaking speech-in-noise tasks across two sessions, approximately a week apart. They listened to sentences and word lists at varying signal-to-noise ratios (SNRs) (-9, -6, -3 and 0 dB), then retaining them for roughly 3 s. We evaluated the test-retest reliability of self-reported effort ratings, theta (4-7 Hz) and alpha (8-13 Hz) oscillatory power, suggested previously as neural markers of listening effort. Additionally, we examined the reliability of correct word percentages. Both relative and absolute reliability were assessed using intraclass correlation coefficients (ICC) and Bland-Altman analysis. We also computed the standard error of measurement (SEM) and smallest detectable change (SDC). Our findings indicated heightened frontal midline theta power for word lists compared to sentences during the retention phase under high SNRs (0 dB, -3 dB), likely indicating a greater memory load for word lists. We observed SNR's impact on alpha power in the right central region during the listening phase and frontal theta power during the retention phase in sentences. Overall, the reliability analysis demonstrated satisfactory between-session variability for correct words and effort ratings. However, neural measures (frontal midline theta power and right central alpha power) displayed substantial variability, even though group-level outcomes appeared consistent across sessions.

Effects of warm-up exercises on self-assessed vocal effort

PURPOSE

An elevated sense of vocal effort due to increased vocal demand is frequently reported by patients with voice disorders. However, effects of vocal warm-up on self-assessed vocal effort have not been thoroughly examined. A recently developed version of the Borg CR-10 Scale facilitates vocal effort assessments, following different vocal warm-up tasks.

METHODS

Effects of a short (5 min) vocal warm-up on self-assessed vocal effort was evaluated using the Borg CR-10. Twenty-six vocally healthy participants (13F, 13M, mean age 22.6), in two randomised groups, underwent sessions of either reading aloud or semi-occluded vocal tract exercises (SOVTE). Vocal effort was evaluated at four times: pre to post vocal warm-up and two silence periods. Non-parametric analyses for repeated measures and calculations for within-subject standard deviation were applied in group comparisons.

RESULTS

Following vocal warm-up, vocal effort ratings were increased to a statistically significant degree in both intervention groups compared to baseline ratings. After a 5-min rest in silence following completion of the vocal warm-up, vocal effort ratings returned to baseline levels in both groups. The drop in ratings immediately post warm-up compared to 5 min later was statistically significant for the SOVTE group.

CONCLUSIONS

Five minutes of vocal warm-up caused increased self-perceived vocal effort in vocally healthy individuals. The increased sense of effort dissipated faster following warm-up for the SOVTE group. When using the Borg CR-10 scale to track vocal effort, it may be beneficial to apply experience-based anchors.

Development and Validation of an Observational Game Analysis Tool with Artificial Intelligence for Handball: Handball.ai

Performance analysis based on artificial intelligence together with game-related statistical models aims to provide relevant information before, during and after a competition. Due to the evaluation of handball performance focusing mainly on the result and not on the analysis of the dynamics of the game pace through artificial intelligence, the aim of this study was to design and validate a specific handball instrument based on real-time observational methodology capable of identifying, quantifying, classifying and relating individual and collective tactical behaviours during the game. First, an instrument validation by an expert panel was performed. Ten experts answered a questionnaire regarding the relevance and appropriateness of each variable presented. Subsequently, data were validated by two observers (1.5 and 2 years of handball observational analysis experience) recruited to analyse a Champions League match. Instrument validity showed a high accordance degree among experts (Cohen's kappa index (k) = 0.889). For both automatic and manual variables, a very good intra- ((automatic: Cronbach's alpha (α) = 0.984; intra-class correlation coefficient (ICC) = 0.970; k = 0.917) (manual: α = 0.959; ICC = 0.923; k = 0.858)) and inter-observer ((automatic: α = 0.976; ICC = 0.961; k = 0.874) (manual: α = 0.959; ICC = 0.923; k = 0.831) consistency and reliability was found. These results show a high degree of instrument validity, reliability and accuracy providing handball coaches, analysts, and researchers a novel tool to improve handball performance.

Translation and Validation of Low Back Pain Knowledge Questionnaire Among Hindi-Speaking Indian Women

Low back pain (LBP) is a common problem encountered among women worldwide. This research aimed at the cross-cultural translation, adaptation, and equivalence assessment of the Low Back Pain Knowledge Questionnaire (LBPKQ) in the Hindi language. The LBPKQ, originally in English (E-LBPKQ) was translated and validated in the Hindi language (H-LBPKQ). The forward-backward procedure was adapted from the recommended guidelines for cross-cultural adaptation of measures. Psychometric properties of the H-LBPKQ were evaluated among 250 Hindi-speaking Indian women with LBP. Test-retest reliability was evaluated in the first 161 participants of the study sample. The overall LBPKQ scores obtained a mean of 3.1 ± 1.1. The internal consistency was excellent for both E-LBPKQ and H-LBPKQ, with Cronbach's alpha of 0.983 (95% confidence interval [CI], 0.980-0.986) and 0.975 (95% CI, 0.970-0.979), respectively. Construct validity was good, with Kaiser-Meyer-Olkin value of 0.892 for E-LBPKQ and 0.852 for H-LBPKQ. Bartlett's test of sphericity (P < .0001) was significant for E-LBPKQ and H-LBPKQ. Two factors were extracted through principal component analysis. The H-LBPKQ is valid and reliable to assess LBP knowledge among Hindi speaking population. Low LBPKQ scores indicate poor LBP knowledge; hence, LBP sensitization is needed among Indian women.

Novice assessors demonstrate good intra-rater agreement and reliability when determining pressure pain thresholds; a cross-sectional study

Background

Experienced assessors show good intra-rater reproducibility (within-session and between-session agreement and reliability) when using an algometer to determine pressure pain thresholds (PPT). However, it is unknown whether novice assessors perform equally well. This study aimed to determine within and between-session agreement and reliability of PPT measurements performed by novice assessors and explored whether these parameters differed per assessor and algometer type.

Methods

Ten novice assessors measured PPTs over four test locations (tibialis anterior muscle, rectus femoris muscle, extensor carpi radialis brevis muscle and paraspinal muscles C5-C6) in 178 healthy participants, using either a Somedic Type II digital algometer (10 raters; 88 participants) or a Wagner Force Ten FDX 25 digital algometer (nine raters; 90 participants). Prior to the experiment, the novice assessors practiced PPTs for 3 h per algometer. Each assessor measured a different subsample of ~9 participants. For both the individual assessor and for all assessors combined (i.e., the group representing novice assessors), the standard error of measurement (SEM) and coefficient of variation (CV) were calculated to reflect within and between-session agreement. Reliability was assessed using intraclass correlation coefficients (ICC1,1).

Results

Within-session agreement expressed as SEM ranged from 42 to 74 kPa, depending on the test location and device. Between-session agreement, expressed as SEM, ranged from 36 to 76 kPa and the CV ranged from 9-16% per body location. Individual assessors differed from the mean group results, ranging from -55 to +32 kPa or from -9.5 to +6.6 percentage points. Reliability was good to excellent (ICC1,1: 0.87 to 0.95). Results were similar for both types of algometers.

Conclusions

Following 3 h of algometer practice, there were slight differences between assessors, but reproducibility in determining PPTs was overall good.

Weight-bearing cone-beam CT: the need for standardised acquisition protocols and measurements to fulfill high expectations-a review of the literature

Weight bearing CT (WBCT) of the lower extremity is gaining momentum in evaluation of the foot/ankle and knee. A growing number of international studies use WBCT, which is promising for improving our understanding of anatomy and biomechanics during natural loading of the lower extremity. However, we believe there is risk of excessive enthusiasm for WBCT leading to premature application of the technique, before sufficiently robust protocols are in place e.g. standardised limb positioning and imaging planes, choice of anatomical landmarks and image slices used for individual measurements. Lack of standardisation could limit benefits from introducing WBCT in research and clinical practice because useful imaging information could become obscured. Measurements of bones and joints on WBCT are influenced by joint positioning and magnitude of loading, factors that need to be considered within a 3-D coordinate system. A proportion of WBCT studies examine inter- and intraobserver reproducibility for different radiological measurements in the knee or foot with reproducibility generally reported to be high. However, investigations of test-retest reproducibility are still lacking. Thus, the current ability to evaluate, e.g. the effects of surgery or structural disease progression, is questionable. This paper presents an overview of the relevant literature on WBCT in the lower extremity with an emphasis on factors that may affect measurement reproducibility in the foot/ankle and knee. We discuss the caveats of performing WBCT without consensus on imaging procedures and measurements.

Self-assessed tactical skills in tennis players: Psychometric evaluation of the Tactical Skills Questionnaire in Tennis

To our knowledge, no feasible, valid and reliable instrument exists to examine tactical skills over the course of multiple training and game situations in tennis yet. Therefore, the aim of this study was to develop and evaluate the psychometric properties of the Tactical Skills Questionnaire in Tennis (TSQT). The TSQT is a new instrument with closed-ended questions designed to examine tactical skills in tennis players. Participants were 233 competitive tennis players (age: 17.06 ± 4.74 years) competing on national or regional levels. With a principal component analysis (PCA) we identified four theoretically meaningful subscales for the 31-item TSQT: “Anticipation and positioning,” “Game intelligence and adaptability,” “Decision-making,” and “Recognizing game situations” and confirmed them with a confirmatory factor analysis (CFA) (χ² = 527.02, df = 426, p < 0.001, CFI = 0.93, RMSEA = 0.045, SRMR = 0.079). Internal consistency was good, with Cronbach's alpha of 0.89 for the entire scale and McDonald's omega ranging from 0.69 to 0.78 for the separate subscales. A subsample of 57 players completed the TSQT twice to assess test-retest reliability. Absolute test-retest reliability of the subscales was good with no significant differences in mean scores between test and retest (p > 0.05). Relative test-retest reliability was moderate with ICC values ranging from 0.65 to 0.71. National players outperformed regional players on the subscales “Game intelligence and adaptability,” “Decision-making,” and “Recognizing game situations” (p < 0.05), and there was a trend toward significance for “Anticipation and positioning” (p = 0.07). This study supported the psychometric properties of the TSQT. Evaluating tactical skills with the TSQT provides players, coaches and other professionals with insight in players' self-assessed tactical skills over the course of multiple training and game situations. It creates the opportunity for players to reflect on their skills and detect personal development areas with their coach. We advise to use this information as input for tailor-made training programs.

Intrarater Reliability and Agreement of Recommended Performance-Based Tests and Common Muscle Function Tests in Knee Osteoarthritis

BACKGROUND AND PURPOSE

Some uncertainty persists regarding the reproducibility of the recommended core set of performance-based tests, as well as common muscle function tests, when applied in individuals with knee osteoarthritis (KOA). The purpose of this study was to investigate the intrarater reliability and agreement of the recommended core set of performance-based tests and common muscle function tests in KOA.

METHODS

Participants (N=40) with radiographic and/or symptomatic KOA were evaluated twice with a 3-day interval between test sessions using the following tests: Leg extensor (LE) maximal muscle power measured in a Nottingham Power Rig; knee extensor (KE) peak isometric strength measured with a handheld dynamometer; 40-m walk test; 30-second chair-stand test; and 9-step stair climb test. Reliability was assessed using a 2-way, mixed-effects, single-measures model (3,1), absolute agreement-type intraclass correlation coefficient (ICC). Agreement was assessed using 95% limits of agreement (LOA) and LOA relative to the mean score from test and retest (LOA-%).

RESULTS

Reliability for all tests was very high (ICC ≥ 0.97). LOA (LOA-%) was ±32.3 watt (W) (±22%) for LE power; ±22.7 N·m (±24%) for KE strength; ±0.2 m/s (±10%) for 40-m walk test; ±2.4 repetitions (±14%) for 30-second chair-stand test; and ±2 second (±20%) for stair climb test. A potential participant learning effect was found for all 3 performance-based tests, indicated by the significantly better scores at retest.

DISCUSSION

The very high reliability found for the performance-based tests supports findings from previous studies and confirms discriminate reliability of these tests on a group level. Also, very high reliability estimates were demonstrated for both muscle function tests. This study also provided estimates of agreement for both performance-based and muscle function tests, which are important to consider when using these tests on an individual level in clinical practice.

CONCLUSION

When using these tests to monitor changes over time in the clinic, depending on the test, improvements of less than 10% to 24% could be a result of measurement error alone and therefore may not be considered an actual improvement after treatment.

Reliability and characterisation of the 20-maximum trampoline jump test

BACKGROUND: The 20-maximum trampoline jump test is a commonly used performance measure in competitive trampoline gymnastics. However, its reliability and characteristics are poorly understood. OBJECTIVE: To determine the reliability of the 20-maximum trampoline jump test and describe its characteristics. METHODS: Thirty-two national and international level trampoline gymnasts (18 ± 5 years) performed two, 20-maximal straight jump tests, separated by 24–72 hours. Time of flight (total, jumps 1–10 and jumps 11–20), force (average and peak), horizontal displacement and contact time were measured by a competition standard system. Test-retest reliability was assessed using intraclass correlation coefficient (ICC), typical error, and coefficient of variation (CV). RESULTS: Total time of flight significantly decreased between trial 1 (31.80 ± 1.98 s) and trial 2 (31.43 ± 1.99 s; p< 0.05), however test-retest reliability was excellent (ICC = 0.96, CV = 1.3%). Other time of flight and force measures significantly decreased from trial 1 to trial 2, whereas contact time increased. All secondary measures displayed very high ICC (0.95–0.99) and low CV values (0.5–1.9%), except horizontal displacement (ICC = 0.54, CV = 20.6%). CONCLUSION: The 20-maximum test possesses excellent reliability for the assessment of trampoline performance in a wide population of national and international level gymnasts.

Testing the reliability of the Health Literacy Questionnaire with carers of older adults receiving hospital care

OBJECTIVE

To determine the re-test reliability of the Health Literacy Questionnaire (HLQ) with carers of older adults discharged from hospital or attending the outpatient clinic.

METHODS

Carers completed the HLQ twice by telephone and rated the acceptability of completing the tool. Tool completion time was recorded. Correlations were calculated between the test occasions using intraclass correlation coefficients (ICC) and 95% confidence intervals.

RESULTS

Fifty-one carers of older patients participated. The HLQ showed good reliability (ICC = 0.75-0.90) for seven of the nine scales and moderate reliability (0.50-0.74) for the other two scales. Median completion time was 16.5 minutes (range 9-50), and acceptability was rated as 9.5/10.

CONCLUSION

The HLQ is a reliable tool for use with carers of older adults attending hospital. However, the length of time for completion of the HLQ may limit its feasibility for use by hospital staff and carers, given the high stress and time pressures of acute care.

External Responsiveness of the SuperOpTM Device to Assess Recovery After Exercise: A Pilot Study

Post-exercise recovery is a complex process involving a return of performance and a physiological or perceptual feeling close to pre-exercise status. The hypothesis of this study is that the device investigated here is effective in evaluating the recovery state of professional cyclists in order to plan effective training. Ten professional male cyclists belonging to the same team were enrolled in this study. Participants performed a 7-day exercise program [D1, D4, and D7: low-intensity training; D2 and D5: passive recovery; D3: maximum oxygen consumption (VO2Max) test (for maximum mechanical power assessment only); and D6: constant load test]. During the week of monitoring, each morning before getting up, the device assessed each participant's so-called Organic Readiness {OR [arbitrary unit (a.u.)]}, based on blood pressure (BP), heart rate (HR), features of past exercise session, and following self-perceived condition. Based on its readings and algorithm, the device graphically displayed four different colors/values, indicating general exercise recommendations: green/3 = "you can train hard," yellow/2 = "you can train averagely," orange/1 = "you can train lightly," or red/0 = "you should recover passively." During the week of research, morning OR values and Bonferroni post-hoc comparisons showed significant differences between days and, namely, values (1) D2 (after low intensity training) was higher than D4 (after VO2Max test; P = 0.033 and d = 1.296) and (2) D3 and D6 (after passive recovery) were higher than D4 (after VO2Max test; P = 0.006 and d = 2.519) and D5 (after low intensity training; P = 0.033 and d = 1.341). The receiver operating characteristic analysis area under curve (AUC) recorded a result of 0.727 and could differentiate between D3 and D4 with a sensitivity and a specificity of 80%. Preliminarily, the device investigated is a sufficiently effective and sensitive/specific device to assess the recovery state of athletes in order to plan effective training.

CORP: Measurement of upper and lower limb muscle strength and voluntary activation

Muscle strength, the maximal force-generating capacity of a muscle or group of muscles, is regularly assessed in physiological experiments and clinical trials. An understanding of the expected variation in strength and the factors that contribute to this variation is important when designing experiments, describing methodologies, interpreting results, and attempting to replicate methods of others and reproduce their findings. In this review (Cores of Reproducibility in Physiology), we report on the intra- and inter-rater reliability of tests of upper and lower limb muscle strength and voluntary activation in humans. Isometric, isokinetic, and isoinertial strength exhibit good intra-rater reliability in most samples (correlation coefficients ≥0.90). However, some tests of isoinertial strength exhibit systematic bias that is not resolved by familiarization. With the exception of grip strength, few attempts have been made to examine inter-rater reliability of tests of muscle strength. The acute factors most likely to affect muscle strength and serve as a source of its variation from trial-to-trial or day-to-day include attentional focus, breathing technique, remote muscle contractions, rest periods, temperature (core, muscle), time of day, visual feedback, body and limb posture, body stabilization, acute caffeine consumption, dehydration, pain, fatigue from preceding exercise, and static stretching >60 s. Voluntary activation, the nervous system’s ability to drive a muscle to create its maximal force, exhibits good intra-rater reliability when examined with twitch interpolation (correlation coefficients >0.80). However, inter-rater reliability has not been formally examined. The methodological factors most likely to influence voluntary activation are myograph compliance and sensitivity; stimulation location, intensity, and inadvertent stimulation of antagonists; joint angle (muscle length); and the resting twitch.

Absolute or relative voice rest after phonosurgery: a blind randomized prospective clinical trial

OBJECTIVES

The first aim, was to compare participant compliance with postoperative voice rest advice in two groups. The second aim was to compare vocal function and recovery in the short-term, seven days post-surgery and in the long-term, 3-6 months post-surgery.

DESIGN

Preliminary randomized prospective blind clinical trial.

METHODS

Twenty patients scheduled for surgery for benign vocal fold lesions were randomized into seven days of absolute or relative voice rest. Compliance with voice rest advice was monitored with a voice accumulator for seven days following surgery. Vocal recovery was tracked through (a) self-perceived vocal function, (b) perceptual assessments of voice recordings and (c) visual assessment of high resolution and high speed digital imaging (d) vocal stamina and reaction to vocal loading, explored with a vocal loading task.

RESULTS

The absolute voice rest group phonated significantly less than the relative voice rest group during seven days post-surgery, but they were not silent. The absolute voice rest group self-reported more difficulty with compliance than the relative voice rest group. The relative voice rest group coped with significantly more vocal loading at long-term check-up. In the short-term the absolute voice rest group improved morphological recovery to a significant degree, however relative voice rest renders superior long-term recovery.

CONCLUSIONS

Absolute voice rest is difficult to comply with. Neither short-term, nor long-term vocal recovery differed significantly between groups. Within-group comparisons showed significant improvements in vocal stamina, immediate recovery from vocal loading and self-assessments of voice problems only for the group with recommended relative voice rest.

Aerobic Stimulus Induced by Virtual Reality Games in Stroke Survivors

OBJECTIVE

To evaluate whether virtual reality games (VRGs) in stroke survivors produce significant and reproducible heart rate and oxygen consumption (V˙o₂) responses during their execution, corresponding to an intensity between the anaerobic threshold (AT) and the respiratory compensation point (RCP).

DESIGN

Single-subject, repeated-measure design.

SETTING

Stroke survivors registered from a rehabilitation program.

PARTICIPANTS

Chronic hemiparetic stroke survivors (N=12; 10 men; mean age ± SD, 58±12y) rated at 3 or 4 in the Functional Ambulation Categories.

INTERVENTIONS

Participants underwent, in a random order, 2 identical sessions of VRGs (console Xbox 360 + Kinect) and 1 control session (38min watching a movie). The VRG sessions were composed of 4 sets of VRGs (3min of tennis, 1min for changing the game, and 4min of boxing) interspaced with 2 minutes of rest.

MAIN OUTCOME MEASURES

Heart rate and V˙o₂ were measured during the experimental sessions and compared with heart rate and V˙o₂ obtained at AT and RCP assessed during a maximal cardiopulmonary exercise test.

RESULTS

Heart rate and V˙o₂ during VRGs had good reproducibility (intraclass correlation coefficients, ≥.91 and ≥.85, respectively; coefficients of variation, ≤6.7% and ≤13.7%, respectively). Heart rate during VRGs was similar to AT and significantly lower than RCP (P≤.05), while V˙o₂ was significantly lower than AT and RCP (P<.05).

CONCLUSIONS

An acute session of VRGs composed of tennis and boxing games using the console XBox 360 + Kinect promotes reproducible responses of heart rate and V˙o₂ that corresponded, respectively, to AT and below AT, characterizing a low-intensity aerobic stimulus.

Statistical Primer for Athletic Trainers: The Essentials of Understanding Measures of Reliability and Minimal Important Change

OBJECTIVE

  To describe the concepts of measurement reliability and minimal important change.

BACKGROUND

  All measurements have some magnitude of error. Because clinical practice involves measurement, clinicians need to understand measurement reliability. The reliability of an instrument is integral in determining if a change in patient status is meaningful.

DESCRIPTION

  Measurement reliability is the extent to which a test result is consistent and free of error. Three perspectives of reliability-relative reliability, systematic bias, and absolute reliability-are often reported. However, absolute reliability statistics, such as the minimal detectable difference, are most relevant to clinicians because they provide an expected error estimate. The minimal important difference is the smallest change in a treatment outcome that the patient would identify as important.

RECOMMENDATIONS

  Clinicians should use absolute reliability characteristics, preferably the minimal detectable difference, to determine the extent of error around a patient's measurement. The minimal detectable difference, coupled with an appropriately estimated minimal important difference, can assist the practitioner in identifying clinically meaningful changes in patients.

Clinical Utility of Ultrasound Measurements of Plantar Fascia Width and Cross-Sectional AreaA Novel Technique

BACKGROUND

We sought to develop a standardized protocol for ultrasound (US) measurements of plantar fascia (PF) width and cross-sectional area (CSA), which may serve as additional outcome variables during US examinations of both healthy asymptomatic PF and in plantar fasciopathy and determine its interrater and intrarater reliability.

METHODS

Ten healthy individuals (20 feet) were enrolled. Participants were assessed twice by two raters each to determine intrarater and interrater reliability. For each foot, three transverse scans of the central bundle of the PF were taken at its insertion at the medial calcaneal tubercle, identified in real time on the plantar surface of the foot, using a fine wire technique. Reliability was determined using intraclass correlation coefficients (ICC), standard errors of measurement (SEM), and limits of agreement (LOA) expressed as percentages of the mean. Reliability of PF width and CSA measurements was determined using PF width and CSA measurements from one sonogram measured once and the mean of three measurements from three sonograms each measured once.

RESULTS

Ultrasound measurements of PF width and CSA showed a mean of 18.6 ± 2.0 mm and 69.20 ± 13.6 mm² respectively. Intra-reliability within both raters showed an ICC > 0.84 for width and ICC > 0.92 for CSA as well as a SEM% and LOA% < 10% for both width and CSA. Inter-rater reliability showed an ICC of 0.82 for width and 0.87 for CSA as well as a SEM% and LOA% < 10% for width and a SEM% < 10% and LOA% < 20% for CSA. Relative and absolute reliability within and between raters were higher when using the mean of three sonographs compared to one sonograph.

CONCLUSIONS

Using this novel technique, PF CSA and width may be determined reliably using measurements from one sonogram or the mean of three sonograms. Measurement of PF CSA and width in addition to already established thickness and echogenicity measurements provides additional information on structural properties of the PF for clinicians and researchers in healthy and pathologic PF.

Inter-daily variability in body composition among young men

Background

The present study analyses changes in body composition over the course of a working week. The purpose of the study is to identify the size of the changes in the observed parameters by means of typical error of measurement (TE) as the initial value for the interpretation of the detected changes in the repeated measurement in diagnostic practice.

Methods

The researched group consisted of 86 males, aged 21.4 ± 1.0 years. All the participants were free of any medical conditions. The measurement of each participant took place over 1 week from Monday till Friday, in the morning hours. Parameters measured: body mass (BM), total body water (TBW), and body fat (BF). The measurement employed two devices using the bioelectric impedance analysis. These devices were the analyzers Tanita BC 418 MA and Nutriguard MS. In order to assess the differences between the average values, the analysis of repeated measurements was used. To assess the material significance, eta squared was used. TE was used to express the size of the changes in the observed parameters.

Results

A statistically significant difference between the average values of the observed parameters was only detected when using the Tanita BC 418 MA analyzer. Based on the post-hoc tests, these differences in the average values were always detected on Monday and Friday. No material significance was proved, however. The highest TE values were also detected in measurements carried out on Monday and Friday. For BM, the value of TE was 0.6 kg, for TBW 1.0–1.1 %, 0.8–0.9 kg, and for BF 1.2–1.6 %, 1.1–1.3 kg depending on the analyzer used.

Conclusions

The results of the present study demonstrate the stability of parameters of body composition throughout a working week, with the provision that standard measuring conditions are fulfilled. For the purpose of diagnostic practice, when interpreting the results of the repeated measurements, it is advisable to take as provable change caused by the observed factors only the ones whose values exceed the value of a weekly TE or the upper limit of the interval of the measurement reliability.

Is the conditioned pain modulation paradigm reliable? A test-retest assessment using the nociceptive withdrawal reflex

The aim of this study was to determine the reliability of the conditioned pain modulation (CPM) paradigm assessed by an objective electrophysiological method, the nociceptive withdrawal reflex (NWR), and psychophysical measures, using hypothetical sample sizes for future studies as analytical goals. Thirty-four healthy volunteers participated in two identical experimental sessions, separated by 1 to 3 weeks. In each session, the cold pressor test (CPT) was used to induce CPM, and the NWR thresholds, electrical pain detection thresholds and pain intensity ratings after suprathreshold electrical stimulation were assessed before and during CPT. CPM was consistently detected by all methods, and the electrophysiological measures did not introduce additional variation to the assessment. In particular, 99% of the trials resulted in higher NWR thresholds during CPT, with an average increase of 3.4 mA (p<0.001). Similarly, 96% of the trials resulted in higher electrical pain detection thresholds during CPT, with an average increase of 2.2 mA (p<0.001). Pain intensity ratings after suprathreshold electrical stimulation were reduced during CPT in 84% of the trials, displaying an average decrease of 1.5 points in a numeric rating scale (p<0.001). Under these experimental conditions, CPM reliability was acceptable for all assessment methods in terms of sample sizes for potential experiments. The presented results are encouraging with regards to the use of the CPM as an assessment tool in experimental and clinical pain. Trial registration: Clinical Trials.gov NCT01636440.

Variability of the QuantiFERON®-TB gold in-tube test using automated and manual methods

BACKGROUND

The QuantiFERON®-TB Gold In-Tube test (QFT-GIT) detects Mycobacterium tuberculosis (Mtb) infection by measuring release of interferon gamma (IFN-γ) when T-cells (in heparinized whole blood) are stimulated with specific Mtb antigens. The amount of IFN-γ is determined by enzyme-linked immunosorbent assay (ELISA). Automation of the ELISA method may reduce variability. To assess the impact of ELISA automation, we compared QFT-GIT results and variability when ELISAs were performed manually and with automation.

METHODS

Blood was collected into two sets of QFT-GIT tubes and processed at the same time. For each set, IFN-γ was measured in automated and manual ELISAs. Variability in interpretations and IFN-γ measurements was assessed between automated (A1 vs. A2) and manual (M1 vs. M2) ELISAs. Variability in IFN-γ measurements was also assessed on separate groups stratified by the mean of the four ELISAs.

RESULTS

Subjects (N = 146) had two automated and two manual ELISAs completed. Overall, interpretations were discordant for 16 (11%) subjects. Excluding one subject with indeterminate results, 7 (4.8%) subjects had discordant automated interpretations and 10 (6.9%) subjects had discordant manual interpretations (p = 0.17). Quantitative variability was not uniform; within-subject variability was greater with higher IFN-γ measurements and with manual ELISAs. For subjects with mean TB Responses ±0.25 IU/mL of the 0.35 IU/mL cutoff, the within-subject standard deviation for two manual tests was 0.27 (CI95 = 0.22-0.37) IU/mL vs. 0.09 (CI95 = 0.07-0.12) IU/mL for two automated tests.

CONCLUSION

QFT-GIT ELISA automation may reduce variability near the test cutoff. Methodological differences should be considered when interpreting and using IFN-γ release assays (IGRAs).

A critical analysis of test-retest reliability in instrument validation studies of cancer patients under palliative care: a systematic review

BACKGROUND

Patient-reported outcome validation needs to achieve validity and reliability standards. Among reliability analysis parameters, test-retest reliability is an important psychometric property. Retested patients must be in a clinically stable condition. This is particularly problematic in palliative care (PC) settings because advanced cancer patients are prone to a faster rate of clinical deterioration. The aim of this study was to evaluate the methods by which multi-symptom and health-related qualities of life (HRQoL) based on patient-reported outcomes (PROs) have been validated in oncological PC settings with regards to test-retest reliability.

METHODS

A systematic search of PubMed (1966 to June 2013), EMBASE (1980 to June 2013), PsychInfo (1806 to June 2013), CINAHL (1980 to June 2013), and SCIELO (1998 to June 2013), and specific PRO databases was performed. Studies were included if they described a set of validation studies. Studies were included if they described a set of validation studies for an instrument developed to measure multi-symptom or multidimensional HRQoL in advanced cancer patients under PC. The COSMIN checklist was used to rate the methodological quality of the study designs.

RESULTS

We identified 89 validation studies from 746 potentially relevant articles. From those 89 articles, 31 measured test-retest reliability and were included in this review. Upon critical analysis of the overall quality of the criteria used to determine the test-retest reliability, 6 (19.4%), 17 (54.8%), and 8 (25.8%) of these articles were rated as good, fair, or poor, respectively, and no article was classified as excellent. Multi-symptom instruments were retested over a shortened interval when compared to the HRQoL instruments (median values 24 hours and 168 hours, respectively; p = 0.001). Validation studies that included objective confirmation of clinical stability in their design yielded better results for the test-retest analysis with regard to both pain and global HRQoL scores (p < 0.05). The quality of the statistical analysis and its description were of great concern.

CONCLUSION

Test-retest reliability has been infrequently and poorly evaluated. The confirmation of clinical stability was an important factor in our analysis, and we suggest that special attention be focused on clinical stability when designing a PRO validation study that includes advanced cancer patients under PC.

Within-subject interlaboratory variability of QuantiFERON-TB gold in-tube tests

Background

The QuantiFERON®-TB Gold In-Tube test (QFT-GIT) is a viable alternative to the tuberculin skin test (TST) for detecting Mycobacterium tuberculosis infection. However, within-subject variability may limit test utility. To assess variability, we compared results from the same subjects when QFT-GIT enzyme-linked immunosorbent assays (ELISAs) were performed in different laboratories.

Methods

Subjects were recruited at two sites and blood was tested in three labs. Two labs used the same type of automated ELISA workstation, 8-point calibration curves, and electronic data transfer. The third lab used a different automated ELISA workstation, 4-point calibration curves, and manual data entry. Variability was assessed by interpretation agreement and comparison of interferon-γ (IFN-γ) measurements. Data for subjects with discordant interpretations or discrepancies in TB Response >0.05 IU/mL were verified or corrected, and variability was reassessed using a reconciled dataset.

Results

Ninety-seven subjects had results from three labs. Eleven (11.3%) had discordant interpretations and 72 (74.2%) had discrepancies >0.05 IU/mL using unreconciled results. After correction of manual data entry errors for 9 subjects, and exclusion of 6 subjects due to methodological errors, 7 (7.7%) subjects were discordant. Of these, 6 (85.7%) had all TB Responses within 0.25 IU/mL of the manufacturer's recommended cutoff. Non-uniform error of measurement was observed, with greater variation in higher IFN-γ measurements. Within-subject standard deviation for TB Response was as high as 0.16 IU/mL, and limits of agreement ranged from −0.46 to 0.43 IU/mL for subjects with mean TB Response within 0.25 IU/mL of the cutoff.

Conclusion

Greater interlaboratory variability was associated with manual data entry and higher IFN-γ measurements. Manual data entry should be avoided. Because variability in measuring TB Response may affect interpretation, especially near the cutoff, consideration should be given to developing a range of values near the cutoff to be interpreted as “borderline,” rather than negative or positive.

The Bland-Altman method should not be used in regression cross-validation studies

The purpose of this study was to demonstrate the bias in the Bland-Altman (BA) limits of agreement method when it is used to validate regression models. Data from 1,158 men were used to develop three regression equations to estimate maximum oxygen uptake (R2 = .40, .61, and .82, respectively). The equations were evaluated in a cross-validation sample of 581 men. The BA means and differences were correlated (p < .001) in the cross-validation sample for each model (r = .55, .39, and .26, respectively), thus demonstrating bias. The BA method is inappropriate for validation of regression models. Validation of regression equations is properly conducted by plotting the residuals against the estimated values and examining the magnitude of the estimation error.

Intra- and interobserver reliability of quantitative ultrasound measurement of the plantar fascia

PURPOSE

To determine intra- and interobserver reliability and measurement precision of sonographic assessment of plantar fascia thickness when using one, the mean of two, or the mean of three measurements.

METHODS

Two experienced observers scanned 20 healthy subjects twice with 60 minutes between test and retest. A GE LOGIQe ultrasound scanner was used in the study. The built-in software in the scanner was used to measure the thickness of the plantar fascia (PF). Reliability was calculated using intraclass correlation coefficient (ICC) and limits of agreement (LOA).

RESULTS

Intraobserver reliability (ICC) using one measurement was 0.50 for one observer and 0.52 for the other, and using the mean of three measurements intraobserver reliability increased up to 0.77 and 0.67, respectively. Interobserver reliability (ICC) when using one measurement was 0.62 and increased to 0.82 when using the average of three measurements. LOA showed that when using the average of three measurements, LOA decreased to 0.6 mm, corresponding to 17.5% of the mean thickness of the PF.

CONCLUSIONS

The results showed that reliability increases when using the mean of three measurements compared with one. Limits of agreement based on intratester reliability shows that changes in thickness that are larger than 0.6 mm can be considered actual changes in thickness and not a result of measurement error.

Effects of starting strategy on 5-min cycling time-trial performance

The importance of pacing for middle-distance performance is well recognized, yet previous research has produced equivocal results. Twenty-six trained male cyclists (VO2 peak 62.8 +/- 5.9 ml x kg(-1) x min(-1); maximal aerobic power output 340 +/- 43 W; mean +/- s) performed three cycling time-trials where the total external work (102.7 +/- 13.7 kJ) for each trial was identical to the best of two 5-min habituation trials. Markers of aerobic and anaerobic metabolism were assessed in 12 participants. Power output during the first quarter of the time-trials was fixed to control external mechanical work done (25.7 +/- 3.4 kJ) and induce fast-, even-, and slow-starting strategies (60, 75, and 90 s, respectively). Finishing times for the fast-start time-trial (4:53 +/- 0:11 min:s) were shorter than for the even-start (5:04 +/- 0:11 min:s; 95% CI = 5 to 18 s, effect size = 0.65, P < 0.001) and slow-start time-trial (5:09 +/- 0:11 min:s; 95% CI = 7 to 24 s, effect size = 1.00, P < 0.001). Mean VO2 during the fast-start trials (4.31 +/- 0.51 litres x min(-1)) was 0.18 +/- 0.19 litres x min(-1) (95% CI = 0.07 to 0.30 litres x min(-1), effect size = 0.94, P = 0.003) higher than the even- and 0.18 +/- 0.20 litres x min(-1) (95% CI = 0.5 to 0.30 litres x min(-1), effect size = 0.86, P = 0.007) higher than the slow-start time-trial. Oxygen deficit was greatest during the first quarter of the fast-start trial but was lower than the even- and slow-start trials during the second quarter of the trial. Blood lactate and pH were similar between the three trials. In conclusion, performance during a 5-min cycling time-trial was improved with the adoption of a fast- rather than an even- or slow-starting strategy.

Development of an operational fitness test for the Royal Air Force

Since 2002, the Royal Air Force (RAF) has been working towards developing role-related physical tests for use as an operational fitness test (OFT). The purpose of this study was to establish reliability of the OFT (comprising four tests), investigate gym-based tests as predictors of performance and establish performance standards. Fifty-eight RAF personnel performed the OFT on three occasions. A separate cohort carried out fitness and anthropometric tests before performing the OFT, by way of establishing performance predictors. Documented evidence and views of an expert panel were used to determine OFT standards. Reliability ranged from moderate to good for three tests, with one test (Dig) showing poor reliability. The 95% limits of agreement for the prediction models ranged from good to poor (6.7-34.2%). The prediction models were not sufficiently accurate to estimate confidently OFT performance, but could be used as a guide to quantify likely outcome and training needs.

Physiological assessment of aerobic training in soccer

Physiological assessment of soccer training usually refers to the measurement of anatomical, physiological, biochemical and functional changes specific to the sport discipline (training outcome). The quality, quantity and organization of physical exercises (training process) are, on the other hand, usually described by the external work imposed by the coach on his or her athletes. In this review, we demonstrate that this approach is not appropriate in soccer, as training is often based on group exercises. The physiological stress (internal load) induced by such training often differs between individuals. Here, we present some physiological laboratory-based tests and field tests used to evaluate training outcomes in soccer, together with methods based on heart rate and perceived exertion to quantify internal load imposed during training. The integrated physiological assessment of both training outcome and process allows researchers: (1) to improve interpretation of physical tests used to verify the effectiveness of training programmes; (2) to evaluate the organization of the training load in order to design periodization strategies; (3) to identify athletes who are poor responders; (4) to control the compliance of the training completed to that planned by the coach; and (5) to modify the training process before the assessment of its outcome, thus optimizing soccer performance.

Reliability of peak $$\dot V{\text{O}}_2 $$ and maximal cardiac output assessed using thoracic bioimpedance in children

The purpose of this study was to evaluate the reliability of a thoracic electrical bioimpedance based device (PhysioFlow) for the determination of cardiac output and stroke volume during exercise at peak oxygen uptake (peak VO(2) in children. The reliability of peak VO(2) is also reported. Eleven boys and nine girls aged 10-11 years completed a cycle ergometer test to voluntary exhaustion on three occasions each 1 week apart. Peak VO(2) was determined and cardiac output and stroke volume at peak VO(2) were measured using a thoracic bioelectrical impedance device (PhysioFlow). The reliability of peak VO(2) cardiac output and stroke volume were determined initially from pairwise comparisons and subsequently across all three trials analysed together through calculation of typical error and intraclass correlation. The pairwise comparisons revealed no consistent bias across tests for all three measures and there was no evidence of non-uniform errors (heteroscedasticity). When three trials were analysed together typical error expressed as a coefficient of variation was 4.1% for peak VO(2) 9.3% for cardiac output and 9.3% for stroke volume. Results analysed by sex revealed no consistent differences. The PhysioFlow method allows non-invasive, beat-to-beat determination of cardiac output and stroke volume which is feasible for measurements during maximal exercise in children. The reliability of the PhysioFlow falls between that demonstrated for Doppler echocardiography (5%) and CO(2) rebreathing (12%) at maximal exercise but combines the significant advantages of portability, lower expense and requires less technical expertise to obtain reliable results.

Reliability of Biomechanical Variables of Sprint Running

PURPOSE

The purpose of this paper was to report the reliability of variables used in the biomechanical assessment of sprint running and to document how these reliability measures are likely to improve when using the average score of multiple trials.

METHODS

Twenty-eight male athletes performed maximal-effort sprints. Video and ground reaction force data were collected at the 16-m mark. The reliability (systematic bias, random error, and retest correlation) for a single score was calculated for 26 kinematic and 7 kinetic variables. In addition, the reliability (random error and retest correlation) for the average score of 2, 3, 4, and 5 trials was predicted from the reliability of a single score.

RESULTS

For all variables, there was no evidence of systematic bias. The measures of random error and retest correlation differed widely among the variables. Variables describing horizontal velocity of the body's center of mass were the most reliable, whereas variables based on vertical displacement of the body's center of mass or braking ground reaction force were the least reliable. For all variables, reliability improved notably when the average score of multiple trials was the measurement of interest.

CONCLUSION

Although it is up to the researcher to judge whether a measurement is reliable enough for its intended use, some of the lower-reliability variables were possibly too unreliable to monitor small changes in an athlete's performance. Nonetheless, there was a consistent trend for reliability to improve notably when the average score of multiple trials was the measurement of interest. Subsequently, if resources permit, researchers and applied sports-scientists may like to consider using the average score of multiple trials to gain the advantages that improved reliability offers.

Reliability of a device measuring triceps surae muscle fatigability

OBJECTIVE

To examine the test-retest reliability of a protocol using an apparatus designed to standardise the standing heel rise test for the triceps surae muscle.

SUBJECTS

40 healthy subjects volunteered to test short and medium term test-retest reliability (group SM, median age 24 years), and a convenience sample of 38 subjects with a history of unilateral deep vein thrombosis (DVT) volunteered to test long term test-retest reliability (group L, median age 52 years).

DESIGN

Subjects carried out 23 heel rises per minute until either the pace or the height could no longer be maintained. Group SM subjects repeated the test 30 minutes later (short term), and again 48 hours later (medium term). Subjects in group L did the test on the unaffected leg, and repeated the test one week later (long term).

RESULTS

The median number of heel rises achieved per trial in group SM was 34 (range 16 to 120). The intraclass coefficient (ICC) was 0.93 (SEM 2.1) for both 30 minute and 48 hour test-retest reliability. In group L, the median number of heel rises was 27 (range 9 to 97), with ICC 0.88 and SEM 3.4.

CONCLUSIONS

The apparatus is a simple and inexpensive standardised tool that reliably measures triceps surae fatigability in subjects with no current injury. Future research should assess its use in injured patients.

Validation of Pulse Oximetry During Progressive Normobaric Hypoxia Utilizing a Portable Chamber

Validation of pulse oximetry in commercially available normobaric hypoxic chambers (NHC) has not been previously reported. The present study examined the validity of pulse oximetry (SpO2) against direct measurements of arterial oxygen saturation (SaO2) via co-oximetry (AVOXimeter 4000) in 13 young adults age 21.3 ± 0.6 years. Over a period of 2.5 hrs, the inspired fraction of oxygen inside a NHC (Hypoxico, Inc.) was progressively reduced from 20.9% to 11.5%. Measurements of SaO2 at baseline and at 15, 30, 60, 90, 120, and 150 min during the hypoxic exposures were compared with SpO2 estimates of oxygen saturation (Nellcor 295) using reflectance (RS-10, temporal) and transmission (D-25, finger) sensors. Regression analysis and methods for assessing agreement (bias, b; precision, p) of SaO2 with SpO2 were similar (R2 = 0.92, 0.89; b = 0.016, −0.47; p = 2.47, 3.03; RS-10 and D-25, respectively). When SaO2 < 85%, RS-10 had greater validity than D-25 (R2 = 0.73, 0.56; b = 1.38, 1.13; p = 2.72, 4.34; RS-10 and D-25, respectively). In light of these findings, caution should be exercised when monitoring individuals with pulse oximetry during desaturation episodes below 85%. When employing frequent NHC exposures, a priori validation of SpO2 utilized to assess blood oxygen status appears warranted. Key words: oxygen saturation, co-oximetry, altitude

Estimating human energy expenditure: a review of techniques with particular reference to doubly labelled water

This review includes an historical overview of the techniques for measuring energy expenditure (EE). Following this overview, the "gold standard" method of measuring EE, the doubly labelled water (DLW) method, is emphasised. Other methods, such as direct calorimetry, indirect calorimetry systems, heart rate and EE relationships, questionnaires and activity recall, motion sensors, combined heart rate and motion sensors for the estimation of EE are then highlighted in relation to their validation against the DLW method. The major advantages and disadvantages for each method are then considered. The preferred method to determine EE is likely to depend principally on factors such as the number of study participants to be monitored, the time period of measurements and the finances available. Small study participant numbers over a short period may be measured accurately by means of indirect calorimetric methods (stationary and portable systems). For periods over 3-4 days, EE should ideally be measured using the DLW method. However, the use of motion sensors is very promising in the measurement of EE, and has a number of advantages over the DLW method. Furthermore, if used correctly, both heart rate and questionnaire methods may provide valuable estimates of EE. Additional studies are needed to examine the possibility of improving the accuracy of measurement by combining two or more techniques. Such information, if confirmed by scientific rigour, may lead to an improvement in the estimation of EE and population-based physical activity levels. The accurate measurement of physical activity and EE is critical from both a research and health prospective. A consideration of the relevant techniques used for the estimation of EE may also help improve the quality of these frequently reported measurements.

Automated metabolic gas analysis systems: a review

The use of automated metabolic gas analysis systems or metabolic measurement carts (MMC) in exercise studies is common throughout the industrialised world. They have become essential tools for diagnosing many hospital patients, especially those with cardiorespiratory disease. Moreover, the measurement of maximal oxygen uptake (VO2max) is routine for many athletes in fitness laboratories and has become a defacto standard in spite of its limitations. The development of metabolic carts has also facilitated the noninvasive determination of the lactate threshold and cardiac output, respiratory gas exchange kinetics, as well as studies of outdoor activities via small portable systems that often use telemetry. Although the fundamental principles behind the measurement of oxygen uptake (VO2) and carbon dioxide production (VCO2) have not changed, the techniques used have, and indeed, some have almost turned through a full circle. Early scientists often employed a manual Douglas bag method together with separate chemical analyses, but the need for faster and more efficient techniques fuelled the development of semi- and full-automated systems by private and commercial institutions. Yet, recently some scientists are returning back to the traditional Douglas bag or Tissot-spirometer methods, or are using less complex automated systems to not only save capital costs, but also to have greater control over the measurement process. Over the last 40 years, a considerable number of automated systems have been developed, with over a dozen commercial manufacturers producing in excess of 20 different automated systems. The validity and reliability of all these different systems is not well known, with relatively few independent studies having been published in this area. For comparative studies to be possible and to facilitate greater consistency of measurements in test-retest or longitudinal studies of individuals, further knowledge about the performance characteristics of these systems is needed. Such information, along with the costs and the common features associated with these systems, may aid physicians and scientists to select a system that is best suited to their requirements and may also improve the quality of these frequently-reported physiological measures.