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Alan J. McCubbin, Anyi Zhu, Stephanie K. Gaskell and Ricardo J.S. Costa

et al., 2017b ). Although GIS occurs across a wide range of exercise types and durations, its incidence is substantially greater as the exercise duration increases ( Costa et al., 2017b ), particularly while running ( Pfeiffer et al., 2012 ) and in hot ambient conditions ( Snipe & Costa, 2018

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Benjamin Pageaux, Jean Theurel and Romuald Lepers

Prolonged whole-body exercise, such as running or cycling, is well known to induce a decrease in maximal force produced by the knee extensors (ie, muscle fatigue). 1 – 5 This decrease in force production capacity is caused by an inability of the central nervous system to maximally recruit the

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Katja Krustrup Pedersen, Esben Lykke Skovgaard, Ryan Larsen, Mikkel Stengaard, Søren Sørensen and Kristian Overgaard

higher running speeds ( Jørgensen et al., 2009 ; John et al., 2010 ). Notably, emerging evidence suggest that thigh-placed accelerometers may be a valid alternative in order to distinguish between various types of activities, such as sitting, standing, cycling, walking, and running ( Skotte et al., 2014

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Nicolas Berryman, Iñigo Mujika, Denis Arvisais, Marie Roubeix, Carl Binet and Laurent Bosquet

described as a percentage of VO 2 max or maximal heart rate. 3 , 4 In recent years, however, convincing evidence has emerged indicating that strength training may also have a positive impact on middle- and long-distance performance (running, cycling, cross-country skiing) and its key determinants for

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Carlos Balsalobre-Fernández, Hovannes Agopyan and Jean-Benoit Morin

There is a large body of research highlighting the importance of monitoring running mechanics for both performance and injury prevention purposes. 1 – 4 From the performance enhancement perspective, the measurement of leg stiffness, vertical oscillation of the center of mass, and ground contact

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Nicola Giovanelli, Paolo Taboga and Stefano Lazzer

Purpose:

To investigate changes in running mechanics during a 6-h running race.

Methods:

Twelve ultraendurance runners (age 41.9 ± 5.8 y, body mass 68.3 ± 12.6 kg, height 1.72 ± 0.09 m) were asked to run as many 874-m flat loops as possible in 6 h. Running speed, contact time (t c), and aerial time (t a) were measured in the first lap and every 30 ± 2 min during the race. Peak vertical ground-reaction force (F max), stride length (SL), vertical downward displacement of the center of mass (Δz), leg-length change (ΔL), vertical stiffness (k vert), and leg stiffness (k leg) were then estimated.

Results:

Mean distance covered by the athletes during the race was 62.9 ± 7.9 km. Compared with the 1st lap, running speed decreased significantly from 4 h 30 min onward (mean –5.6% ± 0.3%, P < .05), while t c increased after 4 h 30 min of running, reaching the maximum difference after 5 h 30 min (+6.1%, P = .015). Conversely, k vert decreased after 4 h, reaching the lowest value after 5 h 30 min (–6.5%, P = .008); t a and F max decreased after 4 h 30 min through to the end of the race (mean –29.2% and –5.1%, respectively, P < .05). Finally, SL decreased significantly (–5.1%, P = .010) during the last hour of the race.

Conclusions:

Most changes occurred after 4 h continuous self-paced running, suggesting a possible time threshold that could affect performance regardless of absolute running speed.

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Caroline Divert, Heiner Baur, Guillaume Mornieux, Frank Mayer and Alain Belli

When mechanical parameters of running are measured, runners have to be accustomed to testing conditions. Nevertheless, habituated runners could still show slight evolutions of their patterns at the beginning of each new running bout. This study investigated runners' stiffness adjustments during shoe and barefoot running and stiffness evolutions of shoes. Twenty-two runners performed two 4-minute bouts at 3.61 m·s–1 shod and barefoot after a 4-min warm-up period. Vertical and leg stiffness decreased during the shoe condition but remained stable in the barefoot condition, p < 0.001. Moreover, an impactor test showed that shoe stiffness increased significantly during the first 4 minutes, p < 0.001. Beyond the 4th minute, shoe properties remained stable. Even if runners were accustomed to the testing condition, as running pattern remained stable during barefoot running, they adjusted their leg and vertical stiffness during shoe running. Moreover, as measurements were taken after a 4-min warm-up period, it could be assumed that shoe properties were stable. Then the stiffness adjustment observed during shoe running might be due to further habituations of the runners to the shod condition. To conclude, it makes sense to run at least 4 minutes before taking measurements in order to avoid runners' stiffness alteration due to shoe property modifications. However, runners could still adapt to the shoe.

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Georgia M. Black, Tim J. Gabbett, Richard D. Johnston, Geraldine Naughton, Michael H. Cole and Brian Dawson

reported between running intensity and number of interchanges across match-play in elite male footballers. 3 Moreover, these researchers demonstrated that in combination with increased rotations, players who performed better on the Yo-Yo Intermittent Recovery Test Level 2 (Yo-Yo IR2) completed the match

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Volker Scheer, Tanja I. Janssen, Solveig Vieluf and Hans-Christian Heitkamp

Trail running is a popular sport that has recently been recognized by the International Association of the Athletics Federations as a new running discipline hosting its own trail world championships ( www.itra.org ). It is therefore of interest to athletes, coaches, and researchers to find training

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Billy T. Hulin, Tim J. Gabbett, Nathan J. Pickworth, Rich D. Johnston and David G. Jenkins

Injuries adversely affect team success, 1 financial revenue, 2 and performance appraisals of science and medicine staff in team sport. 3 In rugby league players, greater high-intensity intermittent running ability is associated with (1) a higher probability of completing more matches injury free