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Nicola Furlan, Mark Waldron, Kathleen Shorter, Tim J. Gabbett, John Mitchell, Edward Fitzgerald, Mark A. Osborne and Adrian J. Gray

Purpose:

To investigate temporal variation in running intensity across and within halves and evaluate the agreement between match-analysis indices used to identify fluctuations in running intensity in rugby sevens.

Methods:

Data from a 15-Hz global positioning system (GPS) were collected from 12 elite rugby sevens players during the IRB World Sevens Series (N = 21 full games). Kinematic (eg, relative distance [RD]) and energetic (eg, metabolic power [MP]) match-analysis indices were determined from velocity–time curves and used to investigate between-halves variations. Mean MP and RD were used to identify peak 2-minute periods of play. Adjacent 2-minute periods (prepeak and postpeak) were compared with peak periods to identify changes in intensity. MP and RD were expressed relative to maximal oxygen uptake (V̇O2max) and speed at V̇O2max, respectively, and compared in their ability to describe the intensity of peak periods and their temporal occurrence.

Results:

Small to moderate reductions were present for kinematic (RD; 8.9%) and energetic (MP; 6%) indices between halves. Peak periods (RD = 130 m/min, MP =13 W/kg) were higher (P < .001) than the match average (RD = 94 m/min, MP = 9.5 W/kg) and the prepeak and postpeak periods (P < .001). RD underestimated the intensity of peak periods compared with MP (bias 16%, limits of agreement [LoA] ± 6%). Peak periods identified by RD and MP were temporally dissociated (bias 21 s, LoA ± 212 s).

Conclusions:

The findings suggest that running intensity varies between and within halves; however, the index used will influence both the magnitude and the temporal identification of peak periods.

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Federico Schena, Barbara Pellegrini, Cantor Tarperi, Elisa Calabria, Gian Luca Salvagno and Carlo Capelli

The effect of a prolonged running trial on the energy cost of running (C r) during a 60-km ultramarathon simulation at the pace of a 100-km competition was investigated in 13 men (40.8 ± 5.6 y, 70.7 ± 5.5 kg, 177.5 ± 4.5 cm) and 5 women (40.4 ± 2.3 y, 53.7 ± 4.4 kg, 162.4 ± 4.8 cm) who participated in a 60-km trial consisting of 3 consecutive 20-km laps. Oxygen uptake (VO2) at steady state was determined at constant speed before the test and at the end of each lap; stride length (SL) and frequency and contact time were measured at the same time points; serum creatine kinase (S-CPK) was measured before and at the end of the test. C r in J · kg−1 · m−1, as calculated from VO2ss and respiratory-exchange ratio, did not increase with distance. SL significantly decreased with distance. The net increase in S-CPK was linearly related with the percentage increase of C r observed during the trial. It is concluded that, in spite of increased S-CPK, this effort was not able to elicit any peripheral or central fatigue or biomechanical adaptation leading to any modification of C r.

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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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Samuel Ryan, Aaron J. Coutts, Joel Hocking and Thomas Kempton

Purpose:

To examine the influence of a range of individual player characteristics and match-related factors on activity profiles during professional Australian football matches.

Methods:

Global positioning system (GPS) profiles were collected from 34 professional Australian football players from the same club over 15 competition matches. GPS data were classified into relative total and high-speed running (HSR; >20 km/h) distances. Individual player aerobic fitness was determined from a 2-km time trial conducted during the preseason. Each match was classified according to match location, season phase, recovery length, opposition strength, and match outcome. The total number of stoppages during the match was obtained from a commercial statistics provider. A linear mixed model was constructed to examine the influence of player characteristics and match-related factors on both relative total and HSR outputs.

Results:

Player aerobic fitness had a large effect on relative total and HSR distances. Away matches and matches lost produced only small reductions in relative HSR distances, while the number of rotations also had a small positive effect. Matches won, more player rotations, and playing against strong opposition all resulted in small to moderate increases in relative total distance, while early season phase, increased number of stoppages, and away matches resulted in small to moderate reductions in relative total distance.

Conclusions:

There is a likely interplay of factors that influence running performance during Australian football matches. The results highlight the need to consider a variety of contextual factors when interpreting physical output from matches.

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Gianluca Vernillo, Alfredo Brighenti, Eloisa Limonta, Pietro Trabucchi, Davide Malatesta, Grégoire P. Millet and Federico Schena

Purpose:

To quantify changes in skeletal-muscle oxygenation and pulmonary O2 uptake (V̇O2) after an extreme ultratrail running bout.

Methods:

Before (PRE) and after (POST) the race (330-km, 24000 D±), profiles of vastus lateralis muscle oxygenation (ie, oxyhemoglobin [O2Hb], deoxyhemoglobin [HHb], and tissue oxygenation index [TOI]) and V̇O2 were determined in 14 athletes (EXP) and 12 control adults (CON) during two 4-min constant-load cycling bouts at power outputs of 1 (p1) and 1.5 (p1.5) W/kg performed in randomized order.

Results:

At POST, normalized [HHb] values increased (p1, +38.0%; p1.5, +27.9%; P < .05), while normalized [O2Hb] (p1, –20.4%; p1.5, –14.4%; P < .05) and TOI (p1, –17.0%; p1.5, –17.7%; P < .05) decreased in EXP. V̇O2 values were similar (P > 0.05). An “overshoot“ in normalized [HHb]:V̇O2 was observed, although the increase was significant only during p1.5 (+58.7%, P = .003). No difference in the aforementioned variables was noted in CON (P > .05).

Conclusions:

The concentric and, particularly, the eccentric loads characterizing this extreme ultratrail-running bout may have led to variations in muscle structure and function, increasing the local muscle deoxygenation profile and the imbalance between O2 delivery to working muscles and muscle O2 consumption. This highlights the importance of incorporating graded training, particularly downhill bouts, to reduce the negative influence of concentric and severe eccentric loads to the microcirculatory function and to enhance the ability of runners to sustain such loading.

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Luana T. Rossato, Camila T.M. Fernandes, Públio F. Vieira, Flávia M.S. de Branco, Paula C. Nahas, Guilherme M. Puga and Erick P. de Oliveira

runners (24.1 [4.3] y), healthy, uninjured, and trained (VO 2 max = 55.8 [4.7] mL·kg −1 ·min −1 ) participated in this study. The participants had at least 3 years of experience in running and presented an average of training frequency of 6 times per week. In addition, all volunteers were well

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James A. Betts, Emma Stevenson, Clyde Williams, Catrin Sheppard, Edwin Grey and Joe Griffin

Including protein in a carbohydrate solution may accelerate both the rate of glycogen storage and the restoration of exercise capacity following prolonged activity. Two studies were undertaken with nine active men in study A and seven in study B. All participants performed 2 trials, each involving a 90 min run at 70% VO2max followed by a 4 h recovery. During recovery, either a 9.3% carbohydrate solution (CHO) or the same solution plus 1.5% protein (CHO-PRO) was ingested every 30 min in volumes providing either 1.2 g CHO · kg−1 · h−1 (study A) or 0.8 g CHO · kg−1 · h−1 (study B). Exercise capacity was then assessed by run time to exhaustion at 85% VO2max. Ingestion of CHO-PRO elicited greater insulinemic responses than CHO (P ≤ 0.05) but with no differences in run times to exhaustion. Within the context of this experimental design, CHO and CHO-PRO restored running capacity with equal effect.

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Carlo Castagna, Lorenzo Francini, Susana C.A. Póvoas and Stefano D’Ottavio

Purpose:

To examine the acute effects of generic drills (running drills [RDs]) and specific (small-sided-games [SSGs]) long-sprint-ability (LSA) drills on internal and external load of male soccer players.

Methods:

Fourteen academy-level soccer players (mean ± SD age 17.6 ± 0.61 y, height 1.81 ± 0.63 m, body mass 69.53 ± 4.65 kg) performed four 30-s LSA bouts for maintenance (work:rest 1:2) and production (1:5) with RDs and SSGs. Players’ external load was tracked with GPS technology (20-Hz), and heart rate (HR), blood lactate concentration (BLc), and rating of perceived exertion (RPE) were used to characterize players’ internal load. Individual peak BLc was assessed with a 30-s all-out test on a nonmotorized treadmill (NMT).

Results:

Compared with SSGs, the RDs had a greater effect on external load and BLc (large and small, respectively). During SSGs players covered more distance with high-intensity decelerations (moderate to small). Muscular RPE was higher (small to large) in RDs than in SSGs. The production mode exerted a moderate effect on BLc while the maintenance condition elicited higher cardiovascular effects (small to large).

Conclusion:

The results of this study showed the superiority of generic over specific drills in inducing LSA-related physiological responses. In this regard production RDs showed the higher postexercise BLc. Individual peak blood lactate responses were found after the NMT 30-s all-out test, suggesting this drill as a valid option to RDs. The practical physiological diversity among the generic and specific LSA drills here considered enable fitness trainers to modulate prescription of RD and SSG drills for LSA according to training schedule.

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Kagan J. Ducker, Brian Dawson and Karen E. Wallman

Beta-alanine supplementation has been shown to improve exercise performance in short-term, high-intensity efforts.

Purpose:

The aim of this study was to assess if beta-alanine supplementation could improve 800 m track running performance in male recreational club runners (n = 18).

Methods:

Participants completed duplicate trials (2 presupplementation, 2 postsupplementation) of an 800 m race, separated by 28 days of either beta-alanine (n = 9; 80 mg·kg−1BM·day−1) or placebo (n = 9) supplementation.

Results:

Using ANCOVA (presupplementation times as covariate), postsupplementation race times were significantly faster following beta-alanine (p = .02), with post- versus presupplementation race times being faster after beta-alanine (–3.64 ± 2.70 s, –2.46 ± 1.80%) but not placebo (–0.59 ± 2.54 s, –0.37 ± 1.62%). These improvements were supported by a moderate effect size (d = 0.70) and a very likely (99%) benefit in the beta-alanine group after supplementation. Split times (ANCOVA) at 400 m were significantly faster (p = .02) postsupplementation in the beta-alanine group, compared with placebo. This was supported by large effect sizes (d = 1.05–1.19) and a very likely (99%) benefit at the 400 and 800 m splits when comparing pre- to postsupplementation with beta-alanine. In addition, the first and second halves of the race were faster post- compared with presupplementation following beta-alanine (1st half –1.22 ± 1.81 s, likely 78% chance of benefit; 2nd half –2.38 ± 2.31 s, d = 0.83, very likely 98% chance of benefit). No significant differences between groups or pre- and postsupplementation were observed for postrace blood lactate and pH.

Conclusion:

Overall, 28 days of beta-alanine supplementation (80 mg·kg-1BM·day-1) improved 800 m track performance in recreational club runners.

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Kim Hébert-Losier, Kurt Jensen and Hans-Christer Holmberg

Purpose:

Jumping and hopping are used to measure lower-body muscle power, stiffness, and stretch-shortening-cycle utilization in sports, with several studies reporting correlations between such measures and sprinting and/or running abilities in athletes. Neither jumping and hopping nor correlations with sprinting and/or running have been examined in orienteering athletes.

Methods:

The authors investigated squat jump (SJ), countermovement jump (CMJ), standing long jump (SLJ), and hopping performed by 8 elite and 8 amateur male foot-orienteering athletes (29 ± 7 y, 183 ± 5 cm, 73 ± 7 kg) and possible correlations to road, path, and forest running and sprinting performance, as well as running economy, velocity at anaerobic threshold, and peak oxygen uptake (VO2peak) from treadmill assessments.

Results:

During SJs and CMJs, elites demonstrated superior relative peak forces, times to peak force, and prestretch augmentation, albeit lower SJ heights and peak powers. Between-groups differences were unclear for CMJ heights, hopping stiffness, and most SLJ parameters. Large pairwise correlations were observed between relative peak and time to peak forces and sprinting velocities; time to peak forces and running velocities; and prestretch augmentation and forest-running velocities. Prestretch augmentation and time to peak forces were moderately correlated to VO2peak. Correlations between running economy and jumping or hopping were small or trivial.

Conclusions:

Overall, the elites exhibited superior stretch-shortening-cycle utilization and rapid generation of high relative maximal forces, especially vertically. These functional measures were more closely related to sprinting and/or running abilities, indicating benefits of lower-body training in orienteering.