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Gregory Roe, Joshua Darrall-Jones, Kevin Till, Padraic Phibbs, Dale Read, Jonathon Weakley and Ben Jones

This study established the between-days reliability and sensitivity of a countermovement jump (CMJ), plyometric push-up, well-being questionnaire, and whole-blood creatine kinase concentration ([CK]) in elite male youth rugby union players. The study also established the between-days reliability of 1, 2, or 3 CMJs and plyometric-push-up attempts. Twenty-five players completed tests on 2 occasions separated by 5 d (of rest). Between-days typical error, coefficient of variation (CV), and smallest worthwhile change (SWC) were calculated for the well-being questionnaire, [CK], and CMJ and plyometric-push-up metrics (peak/mean power, peak/mean force, height, flight time, and flight-time to contraction-time ratio) for 1 maximal effort or taking the highest score from 2 or 3 maximal efforts. The results suggest that CMJ mean power (2 or 3 attempts), peak force, or mean force and plyometric-push-up mean force (from 2 or 3 attempts) should be used for assessing lower- and upper-body neuromuscular function, respectively, due to both their acceptable reliability (CV < 5%) and good sensitivity (CV < SWC). The well-being questionnaire and [CK] demonstrated between-days CVs >5% (7.1% and 26.1%, respectively) and poor sensitivity (CV > SWC). The findings from this study can be used when interpreting fatigue markers to make an objective decision about a player’s readiness to train or compete.

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Paul F.J. Merkes, Paolo Menaspà and Chris R. Abbiss

Purpose: 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. Methods: A total of 11 recreational male road cyclists rode 250 m in 2 directions at around 25, 32, and 40 km·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. Results: 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. Conclusion: 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 3.9–4.9 km·h−1, although these results should be interpreted with caution because poor reliability of CdA was observed between days.

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Joseph F. Signorile, David Sandler, Fangchao Ma, Steve Bamel, Damian Stanziano, Wes Smith, Bernard A. Roos and Lauran Sandals

This study examined the validity, reliability, and discriminatory capacity of the gallon-jug shelf-transfer (GJST) test. Six hundred fifty-three independent-living older adults (463 women age 72.9 ± 7.0 years, 190 men age 74.3 ± 6.7 years) participated. Participants moved five 1-gallon jugs (≈3.9 kg) from a knee-high to a shoulder-high shelf as quickly as possible. The GJST showed an exponential performance decline with age, and there were significant correlations between the GJST and common functional tests (p < .001). High within-day and between-days reliability was detected. The test also detected differences resulting from training status (p < .01) and training protocols (p < .05). The GJST is a valid, reliable, inexpensive, safe, and easily administered clinical test for identifying physically vulnerable elders who could benefit from interventions such as exercise to improve their physical capacities and maintain independence.

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Brianna M. Papotto, Thomas Rice, Terry Malone, Timothy Butterfield and Tim L. Uhl

Context: Shoulder external rotators are challenged eccentrically throughout the deceleration phase of throwing, which is thought to contribute to overuse injuries. To evaluate the effectiveness of intervention programs, as well as identifying deficits, reliable and responsive measures of isometric and eccentric shoulder external rotation are necessary. Previously, isometric measures have primarily tested a single position, and eccentric measures have not been found to have high reliability. Objective: To examine the between-days reliability of multiple-angle isometric and dynamic eccentric isokinetic testing of shoulder external rotation. Design: Repeated measures. Participants: 10 healthy subjects (age 30 ± 12 y, height 166 ± 13 cm, mass 72 ± 10 kg). Main Outcome Measures: Average isometric peak torque of shoulder external rotation at 7 angles was measured. From these values, the angle of isometric peak torque was calculated. Dynamic eccentric average peak torque, average total work, and average angle of peak torque were measured. Results: Between-days reliability was high for average peak torque during isometric contractions at all angles (ICC ≥ .85), as it was for dynamic eccentric average peak torque (ICC ≥ .97). The estimated angle of isometric peak torque (ICC ≤ .65) was not highly reliable between days. The average angle of peak torque from the eccentric testing produced inconsistent results. Average total work of dynamic eccentric shoulder external rotation was found to be highly reliable between days (ICC ≥ . 97). Conclusion: Aspects of force such as peak torque and total work in isometric and eccentric testing of the shoulder external-rotator muscles can be measured reliably between days and used to objectively evaluate shoulder strength and identify changes when they occur. Angle measurements of peak torque could provide insight into the mechanical properties of the posterior shoulder muscles but were found to be inconsistent between days.

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Olivier Girard, Franck Brocherie, Jean-Benoit Morin and Grégoire P. Millet

Purpose:

To determine the intrasession and intersession (ie, within- and between-days) reliability in treadmill sprinting-performance outcomes and associated running mechanics.

Methods:

After familiarization, 13 male recreational sportsmen (team- and racket-sport background) performed three 5-s sprints on an instrumented treadmill with 2 min recovery on 3 different days, 5–7 d apart. Intrasession (comparison of the 3 sprints of the first session) and intersession (comparison of the average of the 3 sprints across days) reliability of performance, kinetics, kinematics, and spring-mass variables were assessed by intraclass correlation coefficient (ICC) and coefficients of variation (CV%).

Results:

Intrasession reliability was high (ICC > .94 and CV < 8%). Intersession reliability was good for performance indices (.83 < ICC < .89 and CV < 10%, yet with larger variability for mean velocity than for distance covered or propulsive power) and kinetic parameters (ICC > .94 and CV < 5%, yet with larger variability for mean horizontal forces than for mean vertical forces) and ranged from good to high for all kinematic (.88 < ICC < .95 and CV ≤ 3.5%) and spring-mass variables (.86 < ICC < .99 and CV ≤ 6.5%). Compared with intrasession, minimal detectable differences were on average twice larger for intersession designs, except for sprint kinetics.

Conclusion:

Instrumented treadmill sprint offers a reliable method of assessing running mechanics during single sprints either within the same session or between days.

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Allan Munro, Lee Herrington and Michael Carolan

Context:

Two-dimensional (2D) video analysis of frontal-plane dynamic knee valgus during common athletic screening tasks has been purported to identify individuals who may be at high risk of suffering knee injuries such as anterior cruciate ligament tear or patellofemoral pain syndrome. Although the validity of 2D video analysis has been studied, the associated reliability and measurement error have not.

Objective:

To assess the reliability and associated measurement error of a 2D video analysis of lower limb dynamic valgus.

Design:

Reliability study.

Participants:

20 recreationally active university students (10 women age 21.5 ± 2.3 y, height 170.1 ± 6.1 cm, weight 66.2 ± 10.2 kg, and 10 men age 22.6 ± 3.1 y, height 177.9 ± 6.0 cm, weight 75.8 ± 7.9 kg).

Main Outcome Measurement:

Within-day and between-days reliability and measurement-error values of 2D frontal-plane projection angle (FPPA) during common screening tasks.

Interventions:

Participants performed single-leg squat and drop jump and single-leg landings from a standard 28-cm step with standard 2D digital video camera assessment.

Results:

Women demonstrated significantly higher FPPA in all tests except the left single-leg squat. Within-day ICCs showed good reliability and ranged from .59 to .88, and between-days ICCs were good to excellent, ranging from .72 to .91. Standard error of measurement and smallest detectable difference values ranged from 2.72° to 3.01° and 7.54° to 8.93°, respectively.

Conclusions:

2D FPPA has previously been shown to be valid and has now also been shown to be a reliable measure of lower extremity dynamic knee valgus. Using the measurement error values presented along with previously published normative data, clinicians can now make informed judgments about individual performance and changes in performance resulting from interventions.

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Antonio Dello Iacono, Stephanie Valentin, Mark Sanderson and Israel Halperin

kurtosis values and with Shapiro–Wilk test. Within- and between-days reliability of PF outputs were recorded by strain gauge and force plate over both days and was examined using coefficient of variation (CV) and intraclass correlation coefficient (ICC 3,1 ). The average score of the 3 trials per day per

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Jonathon Weakley, Kevin Till, John Sampson, Harry Banyard, Cedric Leduc, Kyle Wilson, Greg Roe and Ben Jones

. Between each maximal effort, a 60-second rest was provided. 13 , 14 Variables that were included in the analysis were CMJ height and relative peak power (PP/BM, watts per kilogram body mass). These variables were selected based on previously published between-days reliability statistics in a similar

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Lindsay T. Starling and Michael I. Lambert

K , et al . Between-days reliability and sensitivity of common fatigue measure in rugby players . Int J Sports Physiol Perform . 2016 ; 11 ( 5 ): 581 – 586 . PubMed ID: 26390328 doi:10.1123/ijspp.2015-0413 10.1123/ijspp.2015-0413 24. Burgess DJ . The research doesn’t always apply: practical

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Mathieu Lacome, Christopher Carling, Jean-Philippe Hager, Gerard Dine and Julien Piscione

-Jones J , Till K , et al . Between-days reliability and sensitivity of common fatigue measures in rugby players . Int J Sports Physiol Perform . 2016 ; 11 : 581 – 586 . PubMed ID: 26390328 doi:10.1123/ijspp.2015-0413 26390328 10.1123/ijspp.2015-0413