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Kurt J. Smith and François Billaut

Purpose:

To understand the role of O2 utilization in the sex differences of fatigue during intermittent activity, we compared the cerebral (prefrontal lobe) and muscle (vastus lateralis) oxygenation of men and women during repeated-sprint exercise (RSE).

Methods:

Ten men and 10 women matched for initial-sprint mechanical work performed ten, 10 s cycle sprints (with 30 s of rest) under normoxic (NM: 21% FIO2) and acute hypoxic (HY: 13% FIO2) conditions in a randomized single-blind and crossover design. Mechanical work was calculated and arterial O2 saturation (SpO2) was estimated via pulse oximetry during every sprint. Cerebral and muscle oxy- (O2Hb) and deoxy-hemoglobin (HHb) were monitored continuously by near-infrared spectroscopy.

Results:

Compared with NM, work decrement was accentuated (P = 0.01) in HY for both men (–16.4 ± 10.3%) and women (–16.8 ± 9.0%). This was associated with lower SpO2 and lower cerebral Δ[O2Hb] in both sexes (–13.6 ± 7.5%, P = .008, and –134.5 ± 73.8%, P = .003, respectively). These HY-induced changes were nearly identical in these men and women matched for initial-sprint work. Muscle Δ[HHb] increased 9-fold (P = .009) and 5-fold (P = .02) in men and women, respectively, and plateaued. This muscle deoxygenation was not exacerbated in HY.

Conclusions:

Results indicate that men and women matched for initial-sprint work experience similar levels of fatigue and systemic, cerebral, and peripheral adjustments during RSE performed in NM and HY. These data suggest that cerebral deoxygenation imposes a limitation to repeated-sprint performance.

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Chris Englert and Alex Bertrams

In the current study, we consider that optimal sprint start performance requires the self-control of responses. Therefore, start performance should depend on athletes’ self-control strength. We assumed that momentary depletion of self-control strength (ego depletion) would either speed up or slow down the initiation of a sprint start, where an initiation that was sped up would carry the increased risk of a false start. Applying a mixed between- (depletion vs. nondepletion) and within- (before vs. after manipulation of depletion) subjects design, we tested the start reaction times of 37 sport students. We found that participants’ start reaction times decelerated after finishing a depleting task, whereas it remained constant in the nondepletion condition. These results indicate that sprint start performance can be impaired by unrelated preceding actions that lower momentary self-control strength. We discuss practical implications in terms of optimizing sprint starts and related overall sprint performance.

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Warren Young, Andrew Russell, Peter Burge, Alex Clarke, Stuart Cormack and Glenn Stewart

Purpose:

The purpose of this study was to determine the relationships between split times within sprint tests over 30 m and 40 m in elite Australian Rules footballers.

Methods:

Data were analyzed from two Australian Football League (AFL) clubs. The first club (n = 35) conducted a 40-m sprint test and recorded split times at 10 m and 20 m. The second club (n = 30) conducted a 30-m sprint test and recorded splits at 10 m and 20 m. Analyses included calculation of Pearson correlations and common variances between all the split times as well as “flying” times (20–40 m for the first club and 20 to 30 m for the second club).

Results:

There was a high correlation (r = 0.94) between 10-m time and 20-m time within each club, indicating these measures assessed very similar speed qualities. The correlations between 10-m time and times to 30 m and 40 m decreased, but still produced common variances of 79% and 66% respectively. However when the “flying” times (20–40 m and 20–30 m) were correlated to 10-m time, the common variances decreased substantially to 25% and 42% respectively, indicating uniqueness.

Conclusions:

It was concluded that 10-m time is a good refection of acceleration capabilities and either 20 to 40 m in a 40-m sprint test or 20 to 30 m in a 30-m sprint test can be used to estimate maximum speed capabilities. It was suggested that sprint tests over 30 m or 40 m can be conducted indoors to provide useful information about independent speed qualities in athletes.

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Nobuaki Tottori, Tadashi Suga, Yuto Miyake, Ryo Tsuchikane, Mitsuo Otsuka, Akinori Nagano, Satoshi Fujita and Tadao Isaka

Superior sprint performance is achieved through the generation of large moments by the muscles crossing the hip, knee, and ankle joints ( 29 ). The magnitudes of these moments are primarily determined by agonist muscle size ( 2 , 11 , 12 , 20 , 32 ). In fact, trunk and lower limb muscles are larger

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David S. Haydon, Ross A. Pinder, Paul N. Grimshaw and William S.P. Robertson

classifications, 1 as well as performance outcomes. 2 Despite an increase in popularity and research in wheelchair rugby (WCR), there is currently a limited understanding of how the level of activity limitation affects key kinematic variables and their impact on chair acceleration and sprint performance

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Mark Glaister, Colin Towey, Owen Jeffries, Daniel Muniz-Pumares, Paul Foley and Gillian McInnes

, depending on which of the 4 receptor subtypes is activated, researchers have begun to consider the effects of caffeine on shorter and more intense exercise paradigms. Most of the research into the effects of caffeine on sprinting performance has been performed using 30-second cycle ergometer sprints usually

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Anne Delextrat, Sinead Mackessy, Luis Arceo-Rendon, Aaron Scanlan, Roger Ramsbottom and Julio Calleja-Gonzalez

metabolic acidosis. These chemical changes were associated with better performance during several types of high-intensity exercise (e.g.,  Bishop et al., 2003 ). In particular, significant improvements in repeated sprint ability performance were observed following acute doses of NaHCO 3 ranging from 0.3 to

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Alice M. Wallett, Amy L. Woods, Nathan Versey, Laura A. Garvican-Lewis, Marijke Welvaert and Kevin G. Thompson

affect the pacing strategy of trained cyclists during a TT. It also sought to determine if TT and sprint performance would be affected. It was hypothesized that TT and sprint performance would decline across the mesocycle and that cyclists would exhibit a more conservative start section during TTs as a

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Reed D. Gurchiek, Hasthika S. Rupasinghe Arachchige Don, Lasanthi C. R. Pelawa Watagoda, Ryan S. McGinnis, Herman van Werkhoven, Alan R. Needle, Jeffrey M. McBride and Alan T. Arnholt

Recent developments in field-based sprint assessments 1 – 5 enable athlete-specific force–velocity profiling allowing targeted training. 6 , 7 These employ a simple model describing a sprinter’s velocity ( v ) over time ( t ) as per the following equation 8 : d v d t = a m − v τ . (1) The model

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Simon Gavanda, Stephan Geisler, Oliver Jan Quittmann and Thorsten Schiffer

In American football (AF), body size, strength, and power are important factors for performance. 1 Previous studies indicated that 1-repetition maximum (1RM), sprint performance, and vertical jumping ability are important predictors for success in AF. 2 Starters are stronger, more powerful, and