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Jasper Gielen, Elise Mehuys, Daniel Berckmans, Romain Meeusen, and Jean-Marie Aerts

intensity was also validated but only during training sessions. For vertical jump training, the load is often arbitrary and simply controlled by the number of jumps performed. 4 In addition to monitoring external loads, such as jumping intensity, wearables are also used to monitor physiological variables

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Phillip M. Bellinger, Cameron Ferguson, Tim Newans, and Clare L. Minahan

/her overall readiness to train and compete. 11 There is a growing body of evidence suggesting that a reduction in subjective wellness has a negative impact on the subsequent external load of training. 4 , 10 Recently, Gallo et al 4 were able to demonstrate that a reduced wellness z score corresponded to

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Muammer Altun

external loads to muscles. 14 However, there are external loads acting on the muscles and joints, such as acceleration, deceleration, jumping to certain heights, and the defensive actions of opponents. 12 , 15 These issues might additionally deteriorate sports movement efficiency. Thus, the

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Yusuf Köklü, Utku Alemdaroğlu, Hamit Cihan, and Del P. Wong

rating of perceived exertion [RPE]) and external loads (eg, total distance covered; maximum speed; quantity of low-, moderate-, and high-intensity running). While high-intensity aerobic training sessions are used for the development of endurance performance in athletes, 1 for soccer players an

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Dawn Scott, Dean Norris, and Ric Lovell

are theoretically able to better tolerate or even perform greater absolute match running performances (if necessary) in matches. Application of player-specific speed thresholds based upon fitness attributes is one method of individualizing the evaluation of external loads in team sports. A number of

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Carlo Castagna, Stefano D’Ottavio, Stefano Cappelli, and Susana Cristina Araújo Póvoas

the relevance of acceleration and deceleration, more than sustained speed in determining external load in all-out SSG. 4 , 5 In this regard, emphasis on players’ maximal or near maximal effort maintenance for a prolonged period of time (ie, 30–40 s) has been proposed as a LSA training aim. 4 The

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Kobe C. Houtmeyers, Werner F. Helsen, Arne Jaspers, Sjaantje Nanne, Shaun McLaren, Jos Vanrenterghem, and Michel S. Brink

. Multiple games were played with each game lasting for 6 minutes. Only the first game of each player was used for analysis. Goalkeepers were not included in the analysis. External load was measured via a local position measurement system (version 05.91 T, Inmotiotec, GmbH). This system has acceptable to

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Sonia Sahli, Haithem Rebai, Mohamed Habib Elleuch, Zouheir Tabka, and Georges Poumarat

Context:

There is limited information about the effects of increasing load while squatting

Objective:

To quantify tibiofemoral joint kinetics during squatting with variable loads.

Setting:

Research laboratory.

Participants:

20 male students.

Intervention:

Tibiofemoral joint kinetics and electromyographic (EMG) activity of four involved muscles were determined by recording the half squat with variable external loads.

Main Outcome Measures:

Tibiofemoral joint force and external moment components and EMG activity of four involved muscles.

Results:

Throughout the exercise, a posterior direction for the antero-posterior shear force and a net extension for the external moment were observed. They increased with knee flexion reaching peak force of 29% of the subject body weight (BW) and moment of 88Nm (without external load). All force and moment components and muscle activities increased as the external load increased.

Conclusion:

These findings suggest that half squat may be safe to use for quadriceps strengthening with very low potential loading on the anterior cruciate ligament (ACL). Our data can help clinicians choose the appropriate external load.

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Carlo Castagna, Matthew Varley, Susana C.A. Póvoas, and Stefano D’Ottavio

Purpose:

To test the interchangeability of 2 match-analysis approaches for external-load detection considering arbitrary selected speeds and metabolic power (MP) thresholds in male top-level soccer.

Methods:

Data analyses were performed considering match physical performance of 60 matches (1200 player cases) of randomly selected Spanish, German, and English first-division championship matches (2013–14 season). Match analysis was performed with a validated semiautomated multicamera system operating at 25 Hz.

Results:

During a match, players covered 10,673 ± 348 m, of which 1778 ± 208 m and 2759 ± 241 m were performed at high intensity, as measured using speed (≥16 km/h, HI) and metabolic power (≥20 W/kg, MPHI) notations. High-intensity notations were nearly perfectly associated (r = .93, P < .0001). A huge method bias (980.63 ± 87.82 m, d = 11.67) was found when considering MPHI and HI. Very large correlations were found between match total distance covered and MPHI (r = .84, P < .0001) and HI (r = .74, P < .0001). Player high-intensity decelerations (≥–2 m/s2) were very largely associated with MPHI (r = .73, P < .0001).

Conclusions:

The speed and MP methods are highly interchangeable at relative level (magnitude rank) but not absolute level (measure magnitude). The 2 physical match-analysis methods can be independently used to track match external load in elite-level players. However, match-analyst decisions must be based on use of a single method to avoid bias in external-load determination.

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Susan K. Grimston, Jack R. Engsberg, Reinhard Kloiber, and David A. Hanley

Increased incidence of stress fracture has been reported for amenorrheic runners, while some studies have reported decreased spinal bone mass in amenorrheic runners. Based on results from these studies, one tends to associate decreased spinal bone mass with an increased risk of stress fracture. The present study compared regional bone mass and external loads during running between six female runners reporting a history of stress fracture (seven tibial and three femoral neck) and eight female runners with no history of stress fracture. Dual photon absorptiometry measures indicated significantly greater spinal (L2-L4) and femoral neck bone mineral density in stress fracture subjects (p<0.05) but no differences between groups for tibial bone density. Normalized forces recorded from Kistler force plates indicated significantly greater vertical propulsive, maximal medial, lateral, and posterior forces for stress fracture subjects during running (p<0.05).