Between-day Reliability Research Articles

Velocity Loss Thresholds Reliably Control Kinetic and Kinematic Outputs during Free Weight Resistance Training.

Exercise velocity and relative velocity loss thresholds (VLTs) are commonly used in velocity-based resistance training. This study aims to quantify the between-day reliability of 10%, 20%, and 30% VLTs on kinetic and kinematic outputs, changes in external load, and repetition characteristics in well-trained athletes. Using a repeated, counter-balanced crossover design, twelve semi-professional athletes completed five sets of the back squat with an external load corresponding to a mean concentric velocity of ~0.70 m·s−1 and a VLT applied. The testing sessions were repeated after four weeks of unstructured training to assess the long-term reliability of each VLT. A coefficient of variation (CV) <10% was used to classify outputs as reliable. Kinetic and kinematic outputs and external load were largely reliable, with only peak power during sets 2–5 within the 10% VLT condition demonstrating a CV >10% (CV: 11.14–14.92%). Alternatively, the repetitions completed within each set showed large variation (CV: 18.92–67.49%). These findings demonstrate that by utilizing VLTs, kinetic and kinematic outputs can be prescribed and replicated across training mesocycles. Thus, for practitioners wishing to reliably control the kinetic and kinematic stimulus that is being applied to their athletes, it is advised that a velocity-based approach is used.

Reliability of Ultrasound Imaging of the Trunk Musculature in Athletes with and without Hamstring Injuries.

Trunk muscles play an important role in providing both mobility and stability during dynamic tasks in athletes. The purpose of this study was to evaluate the within-day and between-day reliability of ultrasound (US) in measuring abdominal and lumbar multifidus muscle (MF) thickness in athletes with and without hamstring strain injury (HSI). Fifteen male soccer players (18-30 years old) with and without HSI were evaluated using two US probes (50 mm linear 7.5 MHZ and 70 mm curvilinear 5 MHz). The abdominal muscle thickness as well as the cross sectional area (CSA) of the MF was measured. To determine within and between days reliabilities, the second and third measurements were repeated with two hours and one week intervals, respectively. Intraclass correlation coefficients for athletes with and without HSI demonstrated good to high reliability for the abdominal muscle thickness (0.82 and 0.93) and CSA of the MF muscle (0.84 and 0.89, respectively). Our results indicated that US seemed to be a reliable instrument to measure abdominal and lumbar multifidus muscle thickness in soccer players with and without HSI. However, further studies are recommended to support the present study findings in other athletes.

Validity And Reliability Of Small Respiratory Chamber To Assess Exercise Energy Expenditure

The recently created small respiratory chambers (FLEX rooms) permit a more affordable solution and faster response time than the larger traditional whole room respiratory chambers. Despite the potential for FLEX to employed to assess acute energy expenditure (EE), it has never been validated for submaximal exercise. PURPOSE: To perform concurrent validation and reliability analysis of indirect calorimetry of FLEX against metabolic carts (Cart) during submaximal cycling. METHODS: Ten healthy participants were included in this study (41.5±15.2 years; BMI=25.8±3.3 kg/m2). Energy expenditure was evaluated on FLEX and mixing chamber Cart, simultaneously. FLEX is an 11,000-liter room operated by a push-pull system and mass flow controllers. Participants performed two submaximal exercise bouts of 30-minutes the same day with a 30-minute resting period between bouts, each bout had a light and a moderate load; they repeated the same protocol after two days. Oxygen uptake (VO2) and CO2 production (VCO2) were derived with the same equation. EE, Net EE, gross efficiency (GE) and net efficiency (NetEF) were calculated for each load (L1 & L2). FLEX within and between-day reliability was calculated by the standard deviation of the differences in kcal/min and %. Repeated measures analysis was utilized to explore differences between Cart and FLEX. RESULTS: EE and NetEE were not significantly different between cart and FLEX technologies (EEL1, FLEX= 4.29 vs. Cart= 4.13 kcal/min, EEL2, FLEX= 6.2 vs. Cart=6.0 kcal/min, P>0.05 for both; NetEEL1, FLEX= 2.7 vs. Cart=2.7 kcal/min, EEL2, FLEX= 4.63 vs. Cart=4.57 kcal/min, P>0.05 for both). GE and NetEF were similar between both systems for all loads (GEL1, FLEX= 11.8% vs. Cart= 12.3%, GEL2, FLEX= 16.3% vs. Cart= 18.9%, P>0.05 for both; NetEFL1, FLEX= 18.8% vs. Cart=18.9%, NetEFL2, FLEX= 22.0% vs. Cart= 22.4%, P>0.05 for both). FLEX assessments of EE were highly reliable within-day (L1= 0.11 kcal/min (2.5%) and L2= 0.07 kcal/min (1.1%)) and between-days (L1= 0.10 kcal/min (2.4%) and L2= 0.14 kcal/min (2.2%)). CONCLUSION: FLEX is a valid and reliable technique to assess energy metabolism during exercise without the cumbersome mouthpiece or mask required by metabolic carts.

Reliability and validity of a mobile home pelvic floor muscle trainer: The Elvie Trainer.

Reliability and validity of force measurement and task detection by the Elvie Trainer were evaluated against an intravaginal dynamometer (IVD) and ultrasound (US) imaging. Women were recruited from local physiotherapy clinics. At the first visit, pelvic floor muscle (PFM) strength and tone were assessed manually. Women performed two sets of three repetitions of rest, PFM maximal voluntary contraction (MVC), and maximal Valsalva maneuver (MVM) tasks in supine and standing, with the Elvie Trainer in situ. Women performed another set of rest and MVC repetitions with a custom IVD in situ. At the second visit, PFM strength and tone were reassessed manually. Women performed two sets of three repetitions of the rest, PFM MVC, and MVM tasks in supine and standing, with the Elvie Trainer in situ. Concurrent US imaging was then acquired during a final set of PFM MVC and MVM repetitions in supine and standing, while the Elvie Trainer remained in situ. Reliability was evaluated using intraclass correlation coefficients. Validity was evaluated using Spearman's/Pearson's correlations and receiver operator characteristic curves. Thirty women participated in the study. The Elvie Trainer MVC force outcomes exhibited excellent within-day and good between-day reliability, but were significantly lower than IVD measures, and exhibited poor relationships with IVD force outcomes. The Elvie Trainer was able to specify correct/incorrect performance of a PFM MVC. The Elvie Trainer exhibits acceptable within-day and between-day reliability and can detect the correct performance of PFM MVCs; however, force measurements are not valid indicators of PFM strength and should not be used to measure outcomes.

The Reliability of Neuromuscular and Perceptual Measures Used to Profile Recovery, and the Time-Course of such Responses following Academy Rugby League Match-Play.

In professional academy rugby league (RL) players, this two-part study examined; (A) the within- and between-day reliability of isometric mid-thigh pulls (IMTP), countermovement jumps (CMJ), and a wellness questionnaire (n = 11), and (B) profiled the responses with acceptable reliability (no between-trial differences and between-day coefficient of variation (CV) ≤10% and intraclass correlation coefficient (ICC) ≥0.8) for 120 h (baseline: −3, +24, +48, +72, +96, +120 h) following RL match-play (n = 10). In part A, force at 200, and 250 ms, and peak force (PF) demonstrated acceptable within- (CV%: 3.67–8.41%, ICC: 0.89–0.93) and between-day (CV%: 4.34–8.62%, ICC: 0.87–0.92) reliability for IMTP. Most CMJ variables demonstrated acceptable within-day reliability (CV%: 3.03–7.34%, ICC: 0.82–0.98), but only six (i.e., flight-time, PF, peak power (PP), relative PP, velocity at take-off (VTO), jump-height (JH)) showed acceptable between-day reliability (CV%: 2.56–6.79%, ICC: 0.83–0.91). Only total wellness demonstrated acceptable between-day reliability (CV%: 7.05%, ICC: 0.90) from the questionnaire. In part B, reductions of 4.75% and 9.23% (vs. baseline; 2.54 m∙s−1; 0.33 m) occurred at +24 h for CMJ VTO, and JH, respectively. Acceptable reliability was observed in some, but not all, variables and the magnitude and time-course of post-match responses were test and variable specific. Practitioners should therefore be mindful of the influence that the choice of recovery monitoring tool may have upon the practical interpretation of the data.

Assessment of Measurement Reliability for the IPN Test in Cardiac Patients.

Cardiological diagnostics use maximal and submaximal tests with increasing load. Maximal stress tests are currently considered the gold standard. The Institut für Prävention und Nachsorge, Cologne (IPN) test may be an alternative when maximal patient load is not indicated. The universality of the test is well-documented in sport, but the reliability of this test is unknown. The aim of this study was to assess between-trial and between-day reliability for parameters assessed by the IPN stress test in cardiological patients.: In a study of 24 patients aged 39 to 79 years with cardiovascular diseases, the IPN cycle ergometer short test was performed (submaximal performance test). The reliability of heart rate, systolic and diastolic pressure, absolute power at submaximal load, relative performance at submaximal load and target heart rate were assessed. Good (Interclass Correlation Coefficient (ICC) values ranged from 0.832 to 0.894) and excellent (ICC values ranged from 0.904 to 0.969) between-trial reliability was noted. Between-day reliability was good (ICC values from 0.777 to 0.895) and excellent (ICC values from 0.922 to 0.950). The obtained results suggest that the IPN test may be a reliable tool for use in the assessment of cardiological patients, avoiding the implementation of maximal efforts when excessive patient load is not recommended.

Between-Day Reliability of Scapular Locator for Measuring Scapular Position During Arm Elevation in Asymptomatic Participants

ObjectiveThe aim of this study was to assess the between-day reliability of the scapular locator for measuring scapular rotations during arm elevation in patients without shoulder pain/conditions/disorders. MethodsTwenty-three asymptomatic individuals were measured during 2 sessions separated by 24 hours. One observer measured scapular position with a scapular locator while participants held their arms at 30°, 60°, 90°, and 120° elevation in the scapular plane. Three trials were performed for each arm position. ResultsAt 30°, between-day intraclass correlation coefficients (ICCs) for all scapular rotations were poor (ICC 0.10-0.40). At higher arm elevations (60°, 90°, and 120°), ICCs ranged from 0.73 to 0.93 for scapular upward rotation, 0.80 to 0.87 for posterior tilt, and 0.37 to 0.62 for scapular internal rotation. For all scapular rotations, the standard error of measurement was less than 6°, and the smallest detectable difference ranged from 11° to 18°. ConclusionThe findings indicate good to excellent reliability for measuring scapular upward/downward rotation and anterior/posterior tilt between 60° and 120° of shoulder elevation in the scapular plane. However, low reliability was found for all scapular rotations at 30° elevation, and for scapular internal rotation at higher arm elevation.

Effects of high-intensity intervals and moderate-intensity exercise on baroreceptor sensitivity and heart rate variability during recovery.

Numerous studies have examined heart rate variability (HRV) and cardiac baroreceptor sensitivity (BRS) variables during recovery both acutely (under 3 h) and long-term (24, 48, and 72 h) postexercise. However, there is little literature examining HRV and BRS measures between these timepoints. Spontaneous short-term HRV and cardiac BRS measures were collected in 9 participants before and at zero, 1, 2, 4, 6, and 8 h after 3 separate conditions: moderate-intensity continuous exercise (MICE; 45 min at 50% heart rate reserve), high-intensity interval exercise (HIIE; 25 min including ten 1-min intervals at 85% heart rate reserve), and control (30 min quiet rest). HRV measures in the time domain were only affected immediately following HIIE and MICE at hour zero (all p < 0.043), whereas frequency-domain metrics were unaltered (all p > 0.102). These measures were highly consistent across the control day (all p > 0.420). Cardiac BRS was assessed via low-frequency (LF) gain, and revealed reductions following HIIE at hour zero (p < 0.012). Cardiac BRS LF gain remained consistent following MICE and control interventions (all p > 0.280). The common practice of waiting 12 to 24 h is overly conservative as the current findings demonstrate measures return to baseline at ∼60 min after exercise. Moreover, these metrics demonstrated high levels of within- and between-day reliability. Novelty Previously a 12-h minimum restriction from exercise was required before participation in HRV/BRS studies. Recovery from moderate-intensity exercise for HRV and BRS metrics was <60 min; whereas, high-intensity intervals led to alterations for approximately 60 min. Spontaneous HRV and cardiac BRS demonstrated high levels of within-day reproducibility.

Criterion Validity, and Interunit and Between-Day Reliability of the FLEX for Measuring Barbell Velocity During Commonly Used Resistance Training Exercises.

Weakley, J, Chalkley, D, Johnston, R, García-Ramos, A, Townshend, A, Dorrell, H, Pearson, M, Morrison, M, and Cole, M. Criterion validity, and interunit and between-day reliability of the FLEX for measuring barbell velocity during commonly used resistance training exercises. J Strength Cond Res 34(6): 1519-1524, 2020-The aim of this study was to assess the criterion validity, interunit reliability (accounting for technological and biological variance), and between-day reliability of a novel optic laser device (FLEX) for quantifying mean concentric velocity. To assess the validity against a three-dimensional motion capture system and interunit reliability with both technological and biological variation, 18 men and women completed repetitions at 20, 40, 60, 80, 90, and 100% of one repetition maximum in the free-weight barbell back squat and bench press. To assess interunit (technological only) reliability, a purpose-built, calibrated rig completed a set protocol with 2 devices. To assess between-day reliability of the technology, the same protocol was repeated 21 days later. Standardized bias, typical error of the estimate (TEE; %), and Pearson's correlation coefficient (r) were used to assess validity, whereas typical error and coefficient of variation (CV%) were calculated for reliability. Overall, TEE (±90 CL) between the FLEX and criterion measure was 0.03 (±0.004) and 0.04 (±0.005) m·s in the back squat and bench press, respectively. For measures of reliability, overall interunit technological variance (CV% [± 90% confidence interval]) was 3.96% (3.83-4.12) but increased to 9.82% (9.31-10.41) and 9.83% (9.17-10.61) in the back squat and bench press, respectively, when biological variance was introduced. Finally, the overall between-day reliability was 3.77% (3.63-3.91). These findings demonstrate that the FLEX provides valid and reliable mean concentric velocity outputs across a range of velocities. Thus, practitioners can confidently implement this device for the monitoring and prescription of resistance training loads.

Development of a Smartphone-Based Balance Assessment System for Subjects with Stroke.

Stroke is a cerebral artery disease that negatively affects activities of daily living (ADLs) and quality of life (QoL). Smartphones have demonstrated strong potential in assessing balance performance. However, such smartphone-based tools have thus far not been applied to stroke survivors. The purpose of this study was to develop a smartphone-based balance assessment system for subjects who have experienced strokes and evaluate the system feasibility. The smartphone-based balance assessment application was developed with Android Studio, and reliability and validity tests were conducted. The smartphone was used to record data using a built-in accelerometer and gyroscope, and increased changes represented greater instability. Six postures were tested for 30 s each. Ten healthy adults were recruited in the reliability test, and the intraclass correlation coefficient (ICC) was used to analyze the within-day and between-day reliabilities. Eight subjects with chronic stroke and eight healthy adults were recruited for the validity test, in which balance performance was compared to represent the application validity. The ICC values of the reliability tests were at least 0.76 (p = 0.00). The acceleration data exhibited no difference between individuals who have experienced stroke and healthy subjects; however, all six postures were found to differ significantly between the two groups in the gyroscope data. The study demonstrates that the smartphone application provides a convenient, reliable, and valid tool for the balance assessments of subjects who have experienced chronic stroke.

Validity and Reliability of a New Specific Parkour Test: Physiological and Performance Responses.

Main aim of this study was examining validity and reliability of using a new specific Parkour repeated sprint ability test (SPRSA) for assessing repeated sprint ability while facing obstacles and establishing between-day reliability and sensitivity of SPRSA related to its physiological and performance responses. Thirteen high-level traceurs (three females) performed in random order and twice eight tests for assessing a total of 23 variables: SPRSA (a typical maximal-speed shuttle run interspersed with four Parkour competition-common fundamentals) and seven established fitness tests, core stability, hand-grip, vertical-jump, long-jump, pull-up, 300-m shuttle run (as a field test for anaerobic capacity), and Leger test. Except for muscular elasticity index of vertical jump test (intra-class Correlation Coefficient model 3,1 [ICC3,1] = 0.54 [fair]), fitness tests’ ICC3,1s resulted excellent (ICC3,1: 0.93–1.00). SPRSA total time and time of its fastest sprint (SPRSA peak time) were significantly correlated with the majority of core stability (r: −0.79 to 0.59; P < 0.01–0.05), jumping (r: −0.78 to 0.67; P < 0.01–0.05), pull-up tests (r: −0.86; P < 0.01), 300-m shuttle run test total time (r: 0.77–0.82; P < 0.01), and Leger test-estimated VO2 max (r: −0.78; P < 0.01). Principal component analysis (PCA) of the 23 variables led to extraction of four significant components (each due to different variables’ combinations), which explained 90.2% of 23 variables’ total variance. SPRSA (i.e., total and peak time) showed high reliability (ICC3,1: 0.991–0.998 and standard-error-of-measurement %: 0.07–0.32). Finally, SPRSA showed high sensitivity (smallest-worthwhile-change %: 0.29–0.68). Considering its excellent logical and strong ecological validity, SPRSA may serve as a valid specific field test for Parkour sport. In addition, thanks to its high reliability and sensitivity, this test is suitable for monitoring, evaluating, and programming training processes for Parkour practitioners in repeated sprint ability involving crossing obstacles.

1739 Ultrasound Elastography for Gynecological Applications: Preliminary Reliability Analysis

Study Objective This preliminary investigation aimed to evaluate the feasibility of using ultrasound elastography (UE) to evaluate the myometrial and uterine leiomyoma stiffness. Our objectives were to (1) assess the reliability of UE stiffness measures of non-neoplastic myometrium, and (2) compare UE stiffness measures of non-neoplastic myometrium and leiomyomas. Design This preliminary investigation used a prospective, observational design. Setting Motor Function Measurement Laboratory at the University of Ottawa. Patients or Participants Nine healthy women with no gynecologic history (control) and one woman (case) with two asymptomatic uterine leiomyomas (FIGO 6) were recruited from the local community. Interventions Three trials of a 2D UE cineloops were acquired transvaginally (Aixplorer, SuperSonic Imagine) at the frontal midsagittal myometrium and in the sagittal plane of each leiomyoma. The procedure was repeated twice at the first visit (V1S1, V1S2) and again 2-3 days later (V2S1). Participants completed the menstrual bleeding questionnaire (MBQ) at V1S1. Measurements and Main Results Descriptive statistics were used to evaluate normative peak myometrial stiffness, and the reliability of peak tissue stiffness (kPa), averaged across three trials (10 frames/trial), was evaluated using intraclass correlation coefficients (ICCs). The control group (age=30.2±4.4 years, MBQ=11±9) had median parity of 0 (range: 0-1), while the case participant (age=31.4 years, MBQ=13) had parity of one. Peak myometrial tissue stiffness (V1S1=35.9±9.6 kPa, V1S2=34.1±8.8kPa, V2S1=32.7±11.9kPa) exhibited excellent within-session reliability (ICCV1S1=0.89, ICCV1S2=0.92, ICCV2S1=0.96), and good between-session (ICC=0.71) and between-day (ICC=0.76) reliability. The 95% prediction interval for normative myometrial tissue, computed using values recorded from the control group was 18.5-50.0kPa. The peak stiffness of both leiomyomas (Fibroid A = 111.4kPa; Fibroid B = 84.0kPa) well exceeded the 95% prediction interval for unaffected myometrium. Conclusion UE stiffness exhibited good to excellent reliability in non-neoplastic myometrial tissue, and much higher stiffness was observed in the two asymptomatic fibroids, suggesting that UE may have clinical value in this gynecologic population.

NIH Toolbox Cognition Battery in Young and Older Adults: Reliability and Relationship to Adiposity and Physical Activity.

Executive function in normal aging may be modulated by body habitus and adiposity, both factors modified by physical therapist prescriptions. This study measured between-day reliability of executive function metrics in young and older individuals and examined associations between cognition, adiposity, and physical activity. Forty-three young and 24 older participants underwent executive function assessment via the National Institutes of Health Toolbox Cognition Battery (Dimensional Change Card Sort, Flanker Inhibitory Control and Attention [Flanker], and List Sorting Working Memory [List Sorting]) at 7-day intervals. Between-day reliability was assessed via intraclass correlation (ICC). Responsiveness was assessed via between-day effect size and Cohen's d. Forward stepwise linear regression examined associations between cognition and age, body mass index, percent body fat, and a self-report measure of physical activity (International Physical Activity Questionnaire Short Form). Executive function scores were higher for young participants than for older participants (all P < .002), consistent with typical age-related cognitive decline. Reliability of cognitive metrics was higher for older participants (ICC = 0.483-0.917) than for young participants (ICC = 0.386-0.730). Between-day effect sizes were approximately 50% smaller for older participants. Percent body fat significantly correlated with the Flanker Unadjusted Scale (P = .004, R2 = 0.0772). Neither vigorous nor total physical activity correlated with any cognitive metric. Older participants demonstrated greater between-day reliability for executive function measures, while young participants showed greater capacity to improve performance upon repeat exposure to a cognitive test (especially Flanker). Percent body fat correlated significantly with Flanker scores, while body mass index (an indirect measure of body fat) did not. Self-reported physical activity did not correlate with executive function. Cognitive response to physical therapist-prescribed exercise is a fertile ground for future research.

Reliability of the fluctuations within the stride time series measured in runners during treadmill running to exhaustion

BackgroundThe fluctuations within stride time series (i.e., stride time variability and complexity) during running exhibit long-range correlation. Detecting the breakdown of the long-range correlation was proposed for monitoring the occurrence of running-related injuries during running. However, the stride time fluctuations were only measured from the unilateral side. In addition, the reliability of the stride time fluctuations of within-subject repeated measures remains largely unknown, particularly during exhaustive running. PurposesThis study investigated between-side and between-day reliabilities of the stride time variability and complexity of right and left sides during an exhaustive running. MethodsThe stride time variability and complexity of bilateral sides were obtained while 24 healthy participants performed a 31-minute treadmill running at their individual anaerobic threshold speed. Seven of the 24 participants performed the treadmill running test twice at two different days 5–7 days apart. Limits of agreement (LoA) and intraclass correlation coefficient (ICC) were respectively used to assess the absolute and relative between-side and between-day reliabilities. ResultsThe stride time variability and complexity of right and left sides were highly symmetrical (LoA: (-0.500%, 0.459%) and (-0.052, 0.051), respectively; ICC: 0.94 (0.87, 0.97) and 0.98 (0.95, 0.99), respectively). The overall stride time variability and complexity revealed good between-day reliability (LoA: (-1.044%, 0.724%) and (-0.067, 0.115), respectively; ICC: 0.78 (0.45, 0.92) and 0.81 (0.48, 0.93), respectively). However, the segmented stride time complexity showed poor between-day reliability (ICCs<0.40). ConclusionThe findings demonstrated that the stride time series showed equivalent fluctuations between right and left sides and good between-day reliability in fluctuations during exhaustive running. Given the poor between-day reliability in the segmented stride time series, stride time series during exhaustive running could be collected from either right or left side and should be processed as an overall in the future.

Psychometric Properties of Pressure Pain Thresholds Measured in 2 Positions for Adults With and Without Neck-Shoulder Pain and Tenderness

ObjectiveThe purpose of this study was to determine the psychometric properties of pressure pain threshold (PPT) testing in adults with and without neck-shoulder pain and tenderness and to compare the differences in PPT measurements between the seated and prone positions. MethodsThirty asymptomatic adults and 30 symptomatic patients with intermittent neck-shoulder pain and tenderness completed the study. A pressure algometer was used to assess PPTs at specific points on the middle deltoid, levator scapulae, and upper trapezius muscles of the dominant side of the asymptomatic individuals and the painful side of the patients. Four trials were performed on each muscle in both the seated and prone positions. To determine between-day reliability, a subset of the participants returned to repeat the testing. ResultsThe intraclass correlation coefficients showed good to excellent within-session reliability and fair to excellent between-day reliability of PPT measurements in both the seated and prone positions for both groups. There were significant differences between groups for all muscles in both positions (P < .05) except for the upper trapezius muscle in the prone position. In addition, significant differences were found between the 2 testing positions for the middle deltoid and upper trapezius muscles in the symptomatic group and for the middle deltoid muscle in the asymptomatic group. ConclusionThe results of the study suggest that PPT testing could be useful for distinguishing individuals with and without neck-shoulder pain and tenderness. Further, the patient’s position should be considered when testing PPT, specifically at the middle deltoid or upper trapezius muscles.

Reducing Aerodynamic Drag by Adopting a Novel Road-Cycling Sprint Position.

To assess the influence of seated, standing, and forward-standing cycling sprint positions on aerodynamic drag (CdA) and the reproducibility of a field test of CdA calculated in these different positions. A total of 11 recreational male road cyclists rode 250m in 2 directions at around 25, 32, and 40km·h-1 and in each of the 3 positions, resulting in a total of 18 efforts per participant. Riding velocity, power output, wind direction and velocity, road gradient, temperature, relative humidity, and barometric pressure were measured and used to calculate CdA using regression analysis. A main effect of position showed that the average CdA of the 2 d was lower for the forward-standing position (0.295 [0.059]) compared with both the seated (0.363 [0.071], P = .018) and standing positions (0.372 [0.077], P = .037). Seated and standing positions did not differ from each other. Although no significant difference was observed in CdA between the 2 test days, a poor between-days reliability was observed. A novel forward-standing cycling sprint position resulted in 23% and 26% reductions in CdA compared with a seated and standing position, respectively. This decrease in CdA could potentially result in an important increase in cycling sprint velocity of 3.9-4.9km·h-1, although these results should be interpreted with caution because poor reliability of CdA was observed between days.

Improving the measurement of TMS-assessed voluntary activation in the knee extensors.

PurposeTo test the accuracy, validity, reliability and sensitivity of an alternative method for the measure of TMS-assessed voluntary activation (VATMS) in the knee extensors.MethodsTen healthy males (24 ± 5 years) completed a neuromuscular assessment protocol before and after a fatiguing isometric exercise: two sets of five contractions (50%, 62.5%, 75%, 87.5%, 100% Maximal Voluntary Contraction; MVC) with superimposed TMS-evoked twitches for calculation of VATMS using either the first 5 stimulations (1x5C) or all 10 (2x5C). This was performed on two separate occasions (between-day reliability). Accuracy and validity were compared with a routinely used protocol [i.e. 50%, 75%, and 100% of MVC (1x3C) performed three times (3x3C)].Results95% confidence interval for estimated resting twitch, a key determinant of VATMS, was similar between 1x5C, 2x5C, and 3x3C but improved by six-fold when compared to 1x3C (P<0.05). In a fresh state, potentiated twitch force was unchanged following 1x5C but decreased following 2x5C (P<0.05). A recovery was found post-exercise but was smaller for 1x5C compared to 2x5C (P<0.05), with no difference between the latter two (P>0.05). Absolute reliability was strong enough for both 1x5C and 2x5C to depict a true detectable change in the sample’s VATMS following the fatiguing exercise (TEM < 3% at rest, <9% post-exercise) but 2x5C was marginally more sensitive to individual’s changes from baseline.ConclusionBoth 1x5C and 2x5C provide reliable measures of VATMS. However, 1x5C may hold stronger internal validity. Both protocols allow detection of ‘true’ changes in sample’s means but not individual scores following a fatiguing isometric exercise.

Dynamic Postural Stability During Rested and Fatigued Backwards Single-Leg Jump-Landings

Poor time to stabilization (TTS) during backward single-leg jump-landing (BSLJL) is a risk factor for injury. PURPOSE: The purpose of this study was to assess the reliability of TTS and effect of fatigue on TTS. It was hypothesized that TTS would demonstrate adequate reliability, and that fatigue would worsen TTS. METHODS: Nine active subjects (4 F, 5 M, 24.8 ± 3.4 y, 1.77 ± 0.08 m, 74.7 ± 15.3 kg) performed BSLJL on the dominant (D) and non-dominant (ND) leg. BSLJL was performed barefoot by jumping backwards on the test leg over a 0.15 m hurdle, landing on the test leg on a force plate with hands on the hips, and stabilizing as quickly as possible. During session 1, subjects performed 10 trials without familiarization. During session 2, subjects performed 3 trials (PRE), rested for 5 minutes, and re-performed 3 trials (POST). During session 3, subjects completed a 5 to 7 minute fatigue protocol consisting of step-ups, L-drills, vertical jumps, and agility ladder drills between PRE and POST instead of resting. Sessions 2 and 3 were completed in a randomized order. TTS was quantified as time from initial contact to when vertical ground reaction force remained within 5% of the subject’s body mass for 1 s. RMANOVA and paired t-tests were used to compare TTS, and typical error (TE) was used to quantify reliability. Significance was set to p ≤ 0.05. RESULTS: During session 1, BSLJL TTS did not improve over 10 trials on D (p = 0.18) or ND (p = 0.49). During session 2, TTS was similar PRE and POST on D (1.12 ± 0.47 vs 1.17 ± 0.40 s, p = 0.81) and ND (1.27 ± 0.53 vs 1.05 ± 0.57 s, p = 0.09), and had a within-day TE of 0.02 and 0.16 s, respectively. During session 3, TTS was similar PRE and POST on D (1.21 ± 0.32 vs 1.60 ± 1.05 s, p = 0.22), but greater at POST compared to PRE on ND (1.21 ± 0.51 vs 1.60 ± 0.58 s, p = 0.04). The between-day TE assessed using PRE TTS from session 2 and 3 was 0.36 s on D and ND. CONCLUSION: BSLJL learning effects are negligible, although familiarization trials are likely needed. Between-day reliability does not appear adequate. Using TTS to longitudinally monitor injury risk may be inappropriate. Fatigue appears to degrade TTS, but does not affect all subjects equally, and effects may be masked by large inter-subject variation in TTS. Identifying factors related to susceptibility to fatigue induced decrements may improve injury prevention measures.

The Reliability of Lower-Limb Pulse-Wave Velocity Assessments Using an Oscillometric Technique

Sedentary behavior appears to target the athero- and arterio-sclerotic susceptible vasculature of the lower extremities. For example, vascular function in the leg is acutely impaired following periods of prolonged sitting. PURPOSE: Studies have relied on techniques which are challenging to perform, therefore impeding further study. Consequently, there is a pressing need to identify precise (reliable), yet simple, techniques for evaluating lower extremity vascular health. Oscillometric assessment of pulse-wave velocity (PWV) in the leg may be one potential solution. The current study aimed to determine the between-day reliability of femoral-ankle PWV (faPWV) in supine and seated positions using the oscillometric-based SphygmoCor XCEL device. METHODS: 15 participants (22.1 y, 80% F; BMI 22.7) were tested on three mornings in a fasted state, separated by a maximum of 7 days. In a balanced, randomized order, faPWV was measured in sitting and supine positions using SphygmoCor XCEL. Carotid-femoral PWV (cfPWV) was also assessed for quality control. RESULTS: The intra-class correlation coefficient (ICC) for supine faPWV (ICC = 0.89) was above the 0.75 criterion, but not for seated (ICC = 0.54). The standard error of measurement (SEM) was 0.42 m/s and 0.95 m/s in the supine and seated positions, respectively. Similarly, reliability measures for cfPWV met the criterion in the supine (ICC = 0.75, SEM = 0.42 m/s) but not seated positions (ICC = 0.66, SEM = 0.48 m/s). CONCLUSIONS: These findings indicate that, in a healthy cohort, faPWV can be determined in supine position with acceptable precision using SphygmoCor XCEL. The next step is to measure precision in populations of varying age and health states. The use of these devices may provide researchers with a simple and precise way of investigating the impact of sedentary behaviors.

The validity and reliability of the Vail Sport Test™ as a measure of performance following anterior cruciate ligament reconstruction

ObjectivesTo determine the validity and inter-session reliability of the Vail Sport Test™. DesignCohort study-exploratory methodological research design. SettingClinical Research Laboratory. ParticipantsForty-eight participants who underwent ACL-R. Main outcome measureParticipants performance on the Vail Sport Test™ was graded by an experienced rater in real-time, and simultaneously recorded by a three-dimensional (3D) motion capture system. Construct validity was assessed using the reference standards of the camera system and the IKDC short form. To determine the between-day reliability, a subset of participants returned to repeat the test. ResultsThere were no significant difference between the scores collected in real-time and from the kinematic data on the involved limb (p = 0.222). There was a significant difference for the uninvolved limb (p = 0.015). There was no significant difference between the scores collected in real time and those of the IKDC (p = 0.885). Good inter-session reliability (ICC = 0.787) was found for the involved limb. ConclusionThe results of this study showed good reliability and partially support the validity of the Vail Sport Test as a measure of readiness to return to play.