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Yaheli Bet-Or, Wolbert van den Hoorn, Venerina Johnston and Shaun O’Leary

explored. 1 , 13 , 14 The purpose of this study was to evaluate the reliability and validity of the AMC method in tracking scapular orientation at active end range clavicle protraction, retraction, elevation, and depression. Validity was evaluated by comparing AMC recordings to that of a scapular

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Nick Dobbin, Jamie Highton, Samantha L. Moss and Craig Twist

, discriminant validity) are required. 2 , 3 The majority of studies to date examining the anthropometric and physical characteristics of rugby league players have collected data from a single club with relatively small sample sizes. 11 , 14 , 16 These limitations could be addressed with a national standardized testing

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Jose A. Rodríguez-Marroyo, Javier Medina-Carrillo, Juan García-López, Juan C. Morante, José G. Villa and Carl Foster

Purpose:

To analyze the concurrent and construct validity of a volleyball intermittent endurance test (VIET). The VIET’s test–retest reliability and sensitivity to assess seasonal changes was also studied.

Methods:

During the preseason, 71 volleyball players of different competitive levels took part in this study. All performed the VIET and a graded treadmill test with gas-exchange measurement (GXT). Thirty-one of the players performed an additional VIET to analyze the test–retest reliability. To test the VIET’s sensitivity, 28 players repeated the VIET and GXT at the end of their season.

Results:

Significant (P < .001) relationships between VIET distance and maximal oxygen uptake (r = .74) and GXT maximal speed (r = .78) were observed. There were no significant differences between the VIET performance test and retest (1542.1 ± 338.1 vs 1567.1 ± 358.2 m). Significant (P < .001) relationships and intraclass correlation coefficient (ICC) were found (r = .95, ICC = .96) for VIET performance. VIET performance increased significantly (P < .001) with player performance level and was sensitive to fitness changes across the season (1458.8 ± 343.5 vs 1581.1 ± 334.0 m, P < .01).

Conclusions:

The VIET may be considered a valid, reliable, and sensitive test to assess the aerobic endurance in volleyball players.

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Sean P. Flanagan and George J. Salem

In the analysis of human movement, researchers often sum individual joint kinetics to obtain a single measure of lower extremity function. The extent to which these summed measures relate to the mechanical objectives of the task has not been formally validated. The criterion validity of these measures was established with comparisons to the mechanical objective of two multiple-joint tasks. For the Work task 18 participants performed a loaded barbell squat using 4 resistances while instrumented for biomechanical analysis. For the Power they performed 2 predetermined amounts of work at both self-selected and fast speeds. Using inverse dynamics techniques, the peak net joint moment (PM) was calculated bilaterally in the sagittal plane at the ankle, knee, and hip and was summed into a single measure. This measure was correlated with the task objectives using simple linear regression. Similar procedures were used for the average net joint moment (AM), peak (PP), and average (AP) net joint moment power, and the net joint moment impulse (IM) and work (IP). For the Work task all 6 measures were significantly correlated with the task objective, but only AM, PM, and IP had correlation coefficients above 0.90. For the Power task, IM was not significantly correlated with the task objective, and only AP had a correlation coefficient above 0.90. These findings indicate that the validity of summing individual kinetic measures depends on both the measure chosen and the mechanical objective of the task.

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Herbert Hatze

The validity and reliability of the jumping ergometer method for evaluating performance in two-legged vertical countermovement and serial rebound jumps were investigated. The internal segmental and nonvertical energy flow components for drop jumps were also studied. The exact dynamic equations governing the jumping motion in three dimensions were derived and used together with the approximate relations of the jumping ergometer method to evaluate a total of 72 vertical jumps of different types executed by 22 subjects (15 males, 7 females), average age 24.59 years. The force-plate method was selected as a reference procedure, to which the jumping ergometer results were related. For countermovement jumps, the relative error for jumping height was 3.55% (±2.92%), and for average power per kilogram body mass during the propulsion phase it was 23.79% (±4.85%). For serial rebound jumps, the respective errors were 7.40% (±4.58%) and 5.09% (±4.48%). Internal and nonvertical energy flow components amounted to about 3% of the total. It was concluded that, because of a number of invalid assumptions, unpredictable errors, and contradictory performance requirements, the validity and reliability of the jumping ergometer method for evaluating certain aspects of athletic performance are highly questionable.

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Corrado Lupo, Alexandru Nicolae Ungureanu, Riccardo Frati, Matteo Panichi, Simone Grillo and Paolo Riccardo Brustio

, among team sports, basketball is characterized by progressive rule changes, which contribute to make interpretation of the ITL difficult without a valid method. In fact, basketball is characterized by intermittent high-intensity actions, 5 especially after rule modifications (offense from 30 to 24 s

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Greg Henry, Brian Dawson, Brendan Lay and Warren Young

Purpose:

To study the validity of a video-based reactive agility test in Australian footballers.

Methods:

15 higher performance, 15 lower performance, and 12 nonfootballers completed a light-based reactive agility test (LRAT), a video-based reactive agility test (VRAT), and a planned test (PLAN).

Results:

With skill groups pooled, agility time in PLAN (1346 ± 66 ms) was significantly faster (P = .001) than both reactive tests (VRAT = 1550 ± 102 ms; LRAT = 1572 ± 97 ms). In addition, decision time was significantly faster (P = .001; d = 0.8) in LRAT (278 ± 36 ms) than VRAT (311 ± 47 ms). The correlation in agility time between the two reactive tests (r = .75) was higher than between the planned and reactive tests (r = .41–.68). Higher performance players had faster agility and movement times on VRAT (agility, 130 ± 24 ms, d = 1.27, P = .004; movement, 69 ± 73 ms, d = 0.88, P = .1) and LRAT (agility, 95 ± 86 ms, d = 0.99, P = .08; movement, 79 ± 74 ms; d = 0.9; P = .08) than the nonfootballers. In addition, higher (55 ± 39 ms, d = 0.87, P = .05) and lower (40 ± 57 ms, d = 0.74, P = .18) performance groups exhibited somewhat faster agility time than nonfootballers on PLAN. Furthermore, higher performance players were somewhat faster than lower performance for agility time on the VRAT (63 ± 85 ms, d = 0.82, P = .16) and decision time on the LRAT (20 ± 39 ms, d = 0.66, P = .21), but there was little difference in PLAN agility time between these groups (15 ± 150 ms, d = 0.24, P = .8).

Conclusions:

Differences in decision-making speed indicate that the sport-specific nature of the VRAT is not duplicated by a light-based stimulus. In addition, the VRAT is somewhat better able to discriminate different groups of Australian footballers than the LRAT. Collectively, this indicates that a video-based test is a more valid assessment tool for examining agility in Australian footballers.

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Tiago V. Barreira, John P. Bennett and Minsoo Kang

Purpose:

To obtain validity evidence for the measurement of step counts by spring-levered and piezoelectric pedometers during dance.

Methods:

Thirty-five adults in a college dance class participated in this study. Participants completed trials of 3- and 5-min of different styles of dance wearing Walk4life MVP and Omron HJ-303 pedometers, while their steps were visually counted. Pearson correlation, paired t-test, mean absolute percent error (MAPE), and mean bias were calculated between actual step and pedometer step counts for the 3- and 5-min dances separately.

Results:

For the Walk4life trials the correlations were .92 and .77 for the 3- and 5-min dances. No significant differences were shown by t-test for the 3- (P = .16) and 5-min dances (P = .60). However, MAPE was high, 17.7 ± 17.7% and 19.4 ± 18.3% for the 2 dance durations, respectively. For the Omron, the correlations were .44 and .58 for the 3- and 5-min dances, respectively. No significant differences were shown by t-test for the 3-min (P = .38) and for the 5-min (P = .88) dances. However, MAPE was high, 19.3 ± 16.4% and 26.6 ± 15.2% for the 2 dance durations, respectively.

Conclusions:

This study demonstrated that pedometers can be used to estimate the number of steps taken by a group of college students while dancing, however caution is necessary with individual values.

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Benjamin W. Infantolino, Daniel J. Gales, Samantha L. Winter and John H. Challis

The purpose of this study was to validate ultrasound muscle volume estimation in vivo. To examine validity, vastus lateralis ultrasound images were collected from cadavers before muscle dissection; after dissection, the volumes were determined by hydrostatic weighing. Seven thighs from cadaver specimens were scanned using a 7.5-MHz ultrasound probe (SSD-1000, Aloka, Japan). The perimeter of the vastus lateralis was identified in the ultrasound images and manually digitized. Volumes were then estimated using the Cavalieri principle, by measuring the image areas of sets of parallel two-dimensional slices through the muscles. The muscles were then dissected from the cadavers, and muscle volume was determined via hydrostatic weighing. There was no statistically significant difference between the ultrasound estimation of muscle volume and that estimated using hydrostatic weighing (p > 0.05). The mean percentage error between the two volume estimates was 0.4% ± 6.9. Three operators all performed four digitizations of all images from one randomly selected muscle; there was no statistical difference between operators or trials and the intraclass correlation was high (>0.8). The results of this study indicate that ultrasound is an accurate method for estimating muscle volumes in vivo.

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Emma K. Zadow, Cecilia M. Kitic, Sam S.X. Wu, Stuart T. Smith and James W. Fell

Purpose:

To assess the validity of power output settings of the Wahoo KICKR Power Trainer (KICKR) using a dynamic calibration rig (CALRIG) over a range of power outputs and cadences.

Methods:

Using the KICKR to set power outputs, powers of 100–999 W were assessed at cadences (controlled by the CALRIG) of 80, 90, 100, 110, and 120 rpm.

Results:

The KICKR displayed accurate measurements of power of 250–700 W at cadences of 80–120 rpm with a bias of –1.1% (95% limits of agreement [LoA] –3.6% to 1.4%). A larger mean bias in power was observed across the full range of power tested, 100–999 W (4.2%, 95% LoA –20.1% to 28.6%), due to larger biases of 100–200 and 750–999 W (4.5%, 95% LoA –2.3% to 11.3%, and 13.0%, 95% LoA –24.4% to 50.3%), respectively.

Conclusions:

Compared with a CALRIG, the KICKR has acceptable accuracy reporting a small mean bias and narrow LoA in the measurement of power output of 250–700 W at cadences of 80–120 rpm. Caution should be applied by coaches and sports scientists when using the KICKR at power outputs of <200 W and >750 W due to the greater variability in recorded power.