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  • Author: Ming-Chang Tsai x
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Ming-Chang Tsai and Scott G. Thomas

Purpose:

To validate the 3-minute all-out exercise test (3MT) protocol against the traditional critical-speed (CS) model (CSM) in front-crawl swimming.

Methods:

Ten healthy swimmers or triathletes (mean ± SD age 35.2 ± 10.5 y, height 176.5 ± 5.4 cm, body mass 69.6 ± 8.2 kg) completed 5 tests (3MT, 100m, 200m, 400m, 800m) over 2 wk on separate days. Traditional CS and anaerobic distance capacity (D′) were determined for each of the 3 traditional CSMs (linear distance-time, LIN; linear speed/time, INV; nonlinear time-speed, NLIN) from the 4 set-distance time trials. For the 3MT, CS was determined as the mean speed during the final 30 s of the test and D′ was estimated as the power-time integral above the CS.

Results:

Our results indicated no significant difference between the CS estimates determined from the traditional CSM and 3MT except for the INV model (P = .0311). Correlations between traditional CSMs and 3MT were high (r = .95, P < .01) However, D′ differed and post hoc analysis indicated that D′ estimated from 3MT was significantly lower than LIN (P = .0052) and NLIN (P < .0001). Correlations were weak (r < .55, P > .1). In addition, Bland-Altman plots between the traditional CSMs and 3MT CS estimates showed scattered points above and below the zero line, suggesting there is no consistent bias of one approach versus the other.

Conclusions:

The 3MT is a valid protocol for swimming to estimate CS. The demonstrated concurrent validity of the 3MT may allow more widespread use of CSMs to evaluate participants and responses to training.

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Tyler L. Goodale, Tim J. Gabbett, Ming-Chang Tsai, Trent Stellingwerff and Jeremy Sheppard

Purpose:

To evaluate the effects of contextual game factors on activity and physiological profiles of international-level women’s rugby sevens players.

Methods:

Twenty international-level female rugby sevens players from the same national team participated in this study. Global positioning system and heart-rate data were collected at 5 World Rugby Women’s Sevens Series events (2013–14 season).

Results:

Total, moderate-speed (0.2–3.5 m/s), and high-speed running (3.5–5.0 m/s) distances were significantly greater in the first half (20.1% ± 4.1%, 17.6% ± 6.9%, 24.5% ± 7.8%), during losses (11.4% ± 6.1%, 6.1% ± 6.4%, 26.9% ± 9.8%), during losses of large magnitudes (≥2 tries) (12.9% ± 8.8%, 6.8% ± 10.0%, 31.2% ± 14.9%), and against top-4 opponents (12.6% ± 8.7%, 11.3% ± 8.5%, 15.5% ± 13.9%). In addition, total distance increased (5.0% ± 5.5%) significantly from day 1 to day 2 of tournaments, and very-high-speed (5.0–6.5 m/s) running distance increased significantly (26.0% ± 14.2%) during losses. Time spent between 90% and 100% of maximum heart rate (16.4% ± 14.5%) and player load (19.0% ± 5.1%) were significantly greater in the second half. No significant differences in physiological or activity profiles were observed between forwards and backs.

Conclusions:

Game half, game outcome, tournament day, opponent rank, and margin of outcome all affected activity profiles, whereas game half affected physiological profiles. No differences in activity or physiological profiles were found between playing positions. Practitioners are advised to develop high-speed running ability in women’s rugby sevens players to prepare them to tolerate the varying factors that affect activity profiles.

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Tyler L. Goodale, Tim J. Gabbett, Trent Stellingwerff, Ming-Chang Tsai and Jeremy M. Sheppard

Purpose:

To investigate the physical qualities that differentiate playing minutes in international-level women’s rugby sevens players.

Methods:

Twenty-four national-level female rugby sevens players underwent measurements of anthropometry, acceleration, speed, lower- and upper-body strength, lower-body power, and aerobic fitness. Playing minutes in international competition were used to differentiate players into 2 groups, a high- or low-playing-minutes group. Playing minutes were related to team selection, which was determined by the coaching staff. Playing minutes were therefore used to differentiate performance levels.

Results:

Players in the high-playing-minutes group (≥70 min) were older (mean ± SD 24.3 ± 3.1 vs 21.2 ± 4.3 y, P = .05, effect size [ES] = 0.77 ± 0.66, 90% confidence limit) and had greater experience in a national-training-center environment (2.4 ± 0.8 vs 1.7 ± 0.9 y, P = .03, ES = 0.83 ± 0.65), faster 1600-m time (374.5 ± 20.4 vs 393.5 ± 29.8 s, P = .09, ES = –0.70 ± 0.68), and greater 1-repetition-maximum upper-body strength (bench press 68.4 ± 6.3 vs 62.2 ± 8.1 kg, P = .07, ES = 0.80 ± 0.70, and neutral-grip pull-up 84.0 ± 8.2 vs 79.1 ± 5.4 kg, P = .12, ES = 0.68 ± 0.72) than athletes who played fewer minutes. Age (rs = .59 ± ~.28), training experience (rs = .57 ± ~.29), bench press (r = .44 ± ~.36), and 1600-m time (r = –.43 ± ~.34) were significantly associated with playing minutes. Neutral-grip pull-up and bench press contributed significantly to a discriminant analysis. The average squared canonical correlation was .46. The discriminant analysis predicted 7 of 9 and 6 of 10 high- and low-playing-minutes athletes, respectively.

Conclusions:

Age, training experience, upper-body strength, and aerobic fitness differentiated athlete playing minutes in international women’s rugby sevens.

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Shin-Tsu Chang, Chih-Hung Ku, Ming-Fu Hsieh, Liang-Cheng Chen, Heng-Yi Chu, Cheng-Chiang Chang and Kao-Chung Tsai

Context:

The multifidus muscle plays a role in controlling lumbosacral position and postural sway. One of its attachment sites is the exact site of spina bifida occulta (SBO).

Objective:

To investigate the role of the muscle for postural control in SBO.

Design:

Cross-sectional cohort.

Participants:

Eighty subjects with SBO (38 in minor; 42 in major) and controls.

Interventions:

N/A.

Main Outcome Measures:

Subjects stood upright on a platform at 0° and on an inclined surface (10° and 20°) with feet in plantarflexion/dorsiflexion, together with eyes open and closed. The platform system measured posture to obtain sway area and sway mean for statistics.

Results:

Upon sway area/mean, the group differences of major/minor SBO vs. control were all significant. Sway means of minor SBO were lower than those of major SBO at corresponding inclined degrees.

Conclusions:

Subjects with SBO demonstrated increased sway as compared to controls.