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Jumping and Hopping in Elite and Amateur Orienteering Athletes and Correlations to Sprinting and Running

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.

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Impact of the Steepness of the Slope on the Biomechanics of World Cup Slalom Skiers

Matej Supej, Kim Hébert-Losier, and Hans-Christer Holmberg

Purpose:

Numerous environmental factors can affect alpine-ski-racing performance, including the steepness of the slope. However, little research has focused on this factor. Accordingly, the authors’ aim was to determine the impact of the steepness of the slope on the biomechanics of World Cup slalom ski racers.

Methods:

The authors collected 3-dimensional kinematic data during a World Cup race from 10 male slalom skiers throughout turns performed on a relatively flat (19.8°) and steep (25.2°) slope under otherwise similar course conditions.

Results:

Kinematic data revealed differences between the 2 slopes regarding the turn radii of the skis and center of gravity, velocity, acceleration, and differential specific mechanical energy (all P < .001). Ground-reaction forces (GRFs) also tended toward differences (P = .06). Examining the time-course behaviors of variables during turn cycles indicated that steeper slopes were associated with slower velocities but greater accelerations during turn initiation, narrower turns with peak GRFs concentrated at the midpoint of steering, more pronounced lateral angulations of the knees and hips at the start of steering that later became less pronounced, and overall slower turns that involved deceleration at completion. Consequently, distinct energy-dissipation-patterns were apparent on the 2 slope inclines, with greater pregate and lesser postgate dissipation on the steeper slope. The steepness of the slope also affected the relationships between mechanical skiing variables.

Conclusions:

The findings suggest that specific considerations during training and preparation would benefit the race performance of slalom skiers on courses involving sections of varying steepness.

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There Is No Global Running Pattern More Economic Than Another at Endurance Running Speeds

Aurélien Patoz, Thibault Lussiana, Bastiaan Breine, Cyrille Gindre, and Kim Hébert-Losier

Purpose: The subjective Volodalen® score (V®score) and the objective duty factor metric can both assess global running patterns. The authors aimed to investigate the relation between running economy (RE) at endurance running speeds and the global running pattern quantified using both subjective and objective measures. Methods: RE and 3-dimensional whole-body kinematics were acquired by indirect calorimetry and an optoelectronic system, respectively, for 52 trained runners during treadmill runs at 10, 12, and 14 km/h. Results: Correlations between RE and V®score and RE and duty factor were negligible and nonsignificant across speeds tested (P ≥ .20), except for a low and significant correlation between RE and V®score at 10 km/h. Conclusions: These findings suggest there is no global running pattern more economic than another at endurance running speeds. Therefore, there is no advantage of choosing, favoring, or prescribing one specific global running pattern along a continuum based on V®score or duty factor metrics, and coaches should not try to modify the spontaneous running pattern of runners at endurance running speed to improve RE.

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Biomechanical Changes During a 50-minute Run in Different Footwear and on Various Slopes

Thibault Lussiana, Kim Hébert-Losier, Grégoire P. Millet, and Laurent Mourot

The effects of footwear and inclination on running biomechanics over short intervals are well documented. Although recognized that exercise duration can impact running biomechanics, it remains unclear how biomechanics change over time when running in minimalist shoes and on slopes. Our aims were to describe these biomechanical changes during a 50-minute run and compare them to those observed in standard shoes. Thirteen trained recreational male runners ran 50 minutes at 65% of their maximal aerobic velocity on a treadmill, once in minimalist shoes and once in standard shoes, 1 week apart in a random order. The 50-minute trial was divided into 5-minute segments of running at 0%, +5%, and –5% of treadmill incline sequentially. Data were collected using photocells, high-speed video cameras, and plantar-pressure insoles. At 0% incline, runners exhibited reduced leg stiffness and plantar flexion angles at foot strike and lower plantar pressure at the forefoot and toes in minimalist shoes from minute 34 of the protocol onward. However, only reduced plantar pressure at the toes was observed in standard shoes. Overall, similar biomechanical changes with increased exercise time were observed on the uphill and downhill inclines. The results might be due to the unfamiliarity of subjects to running in minimalist shoes.

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Similar Running Economy With Different Running Patterns Along the Aerial-Terrestrial Continuum

Thibault Lussiana, Cyrille Gindre, Kim Hébert-Losier, Yoshimasa Sagawa, Philippe Gimenez, and Laurent Mourot

Purpose:

No unique or ideal running pattern is the most economical for all runners. Classifying the global running patterns of individuals into 2 categories (aerial and terrestrial) using the Volodalen method could permit a better understanding of the relationship between running economy (RE) and biomechanics. The main purpose was to compare the RE of aerial and terrestrial runners.

Methods:

Two coaches classified 58 runners into aerial (n = 29) or terrestrial (n = 29) running patterns on the basis of visual observations. RE, muscle activity, kinematics, and spatiotemporal parameters of both groups were measured during a 5-min run at 12 km/h on a treadmill. Maximal oxygen uptake (V̇O2max) and peak treadmill speed (PTS) were assessed during an incremental running test.

Results:

No differences were observed between aerial and terrestrial patterns for RE, V̇O2max, and PTS. However, at 12 km/h, aerial runners exhibited earlier gastrocnemius lateralis activation in preparation for contact, less dorsiflexion at ground contact, higher coactivation indexes, and greater leg stiffness during stance phase than terrestrial runners. Terrestrial runners had more pronounced semitendinosus activation at the start and end of the running cycle, shorter flight time, greater leg compression, and a more rear-foot strike.

Conclusions:

Different running patterns were associated with similar RE. Aerial runners appear to rely more on elastic energy utilization with a rapid eccentric-concentric coupling time, whereas terrestrial runners appear to propel the body more forward rather than upward to limit work against gravity. Excluding runners with a mixed running pattern from analyses did not affect study interpretation.

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Effectiveness of an Unexpected Disturbance Program in the Early Stage of Rehabilitation in Athletes With Unilateral Knee Ligament Injury

Joerg Teichmann, Rachel Tan, Kim Hébert-Losier, Yeo Wee Kian, Shabana Jalal Din, Ananthi Subramaniam, Dietmar Schmidtbleicher, and C. Martyn Beaven

Context: Sensorimotor, proprioceptive, and neuromuscular programs are critical for the successful rehabilitation of injured athletes, and these decrease reinjury rates. Objective: To investigate the effects of an unexpected disturbance program (UDP) on balance and unilateral strength metrics in athletes with unilateral knee ligament injury. Design: A 3-week parallel-group experimental design consisting of 9 rehabilitation sessions. Setting: National Sports Institute. Participants: Twenty-one national-level athletes (age 21.4 [4.4] y, body mass 63.9 [10.8] kg, height 169.0 [10.2] cm) who had sustained a unilateral knee ligament injury. Intervention: An UDP program designed to evoke rapid sensorimotor responses was compared with traditional training and a nonexercise control group. Main Outcome Measures: Unilateral total, anteroposterior, and mediolateral sway with eyes open and closed and unilateral isometric strength. Results: Traditional exercises tended to outperform the UDP when unilateral balance testing was performed with eyes open; however, balance improvement following UDP tended to be greater in the eyes-closed condition. Significant strength gains in both the injured and uninjured legs were only observed following the UDP. This increase in unilateral isometric strength was 23.4 and 35.1 kg greater than the strength improvements seen in the traditional rehabilitation and control groups (P < .05). Conclusions: UDP could improve neural aspects of rehabilitation to improve rehabilitation outcomes by improving strength, sensorimotor function, and proprioception. Given the complementary adaptations, an UDP could provide an effective adjunct to traditional rehabilitation protocols and improve return-to-play outcomes.

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Reactive Strength as a Metric for Informing Return-to-Sport Decisions: A Case-Control Study

Jorg Teichmann, Kim Hébert-Losier, Rachel Tan, Han Wei Lem, Shabana Khanum, Ananthi Subramaniam, Wee-Kian Yeo, Dietmar Schmidtbleicher, and Christopher M. Beaven

Objective: Current return-to-sport decisions are primarily based on elapsed time since surgery or injury and strength measures. Given data that show rates of successful return to competitive sport at around 55%, there is strong rationale for adopting tools that will better inform return to sport decisions. The authors’ objective was to assess reactive strength as a metric for informing return-to-sport decisions. Design: Case-control design. Methods: Fifteen elite athletes from national sports teams (23 [6.0] y) in the final phase of their return-to-sport protocol following a unilateral knee injury and 16 age-matched control athletes (22 [4.6] y) performed a unilateral isometric strength test and 24-cm drop jump test. Pairwise comparisons were used to determine differences between legs within groups and differences in interleg asymmetry between groups. Results: Strength measures did not distinguish the control from the rehabilitation group; however, clear differences in the degree of asymmetry were apparent between the control and rehabilitation groups for contact time (Cohen d = 0.56; −0.14 to 1.27; 8.2%; P = .113), flight time (d = 1.10; 0.44 to 1.76; 16.0%; P = .002), and reactive strength index (d = 1.27; 0.50 to 2.04; 22.4%; P = .002). Conclusion: Reactive strength data provide insight into functional deficits that persist into the final phase of a return-to-sport protocol. The authors’ findings support the use of dynamic assessment tools to inform return-to-sport decisions to limit potential for reinjury.

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Improvement of Elite Female Athletes’ Physical Performance With a 3-Week Unexpected Disturbance Program

Jorg Teichmann, Edin K. Suwarganda, C. Martyn Beaven, Kim Hébert-Losier, Jin Wei Lee, Florencio Tenllado Vallejo, Philip Chun Foong Lew, Ramlan Abdul Aziz, Yeo Wee Kian, and Dietmar Schmidtbleicher

Context: Sensorimotor training is commonly used in a rehabilitative setting; however, the effectiveness of an unexpected disturbance program (UDP) to enhance performance measures in uninjured elite athletes is unknown. Objective: To assess the impact of a 3-wk UDP program on strength, power, and proprioceptive measures. Design: Matched-group, pre-post design. Setting: National sport institute. Participants: 21 international-level female field hockey athletes. Intervention: Two 45-min UDP sessions were incorporated into each week of a 3-wk training program (total 6 sessions). Main Outcome Measures: 1-repetition-maximum strength, lower-limb power, 20-m running speed, and proprioception tests were performed before and after the experimental period. Results: Substantial improvements in running sprint speed at 5-m (4.4 ± 2.6%; effect size [ES]: 0.88), 10-m (2.1 ± 1.9%; ES: 0.51), and 20-m (1.0 ± 1.6%; ES: 0.23) were observed in the UDP group. Squat-jump performance was also clearly enhanced when compared to the control group (3.1 ± 6.1%; ES: 0.23). Small but clear improvements in maximal strength were observed in both groups. Conclusions: A 3-wk UDP can elicit clear enhancements in running sprint speed and concentric-only jump performance. These improvements are suggestive of enhanced explosive strength and are particularly notable given the elite training status of the cohort and relatively short duration of the intervention. Thus, the authors would reiterate the statement by Gruber et al (2004) that sensorimotor training is a “highly efficient” modality for improving explosive strength.

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COVID-19 Lockdown: A Global Study Investigating the Effect of Athletes’ Sport Classification and Sex on Training Practices

Jad Adrian Washif, Øyvind Sandbakk, Stephen Seiler, Thomas Haugen, Abdulaziz Farooq, Ken Quarrie, Dina C. Janse van Rensburg, Isabel Krug, Evert Verhagen, Del P. Wong, Iñigo Mujika, Cristina Cortis, Monoem Haddad, Omid Ahmadian, Mahmood Al Jufaili, Ramzi A. Al-Horani, Abdulla Saeed Al-Mohannadi, Asma Aloui, Achraf Ammar, Fitim Arifi, Abdul Rashid Aziz, Mikhail Batuev, Christopher Martyn Beaven, Ralph Beneke, Arben Bici, Pallawi Bishnoi, Lone Bogwasi, Daniel Bok, Omar Boukhris, Daniel Boullosa, Nicola Bragazzi, Joao Brito, Roxana Paola Palacios Cartagena, Anis Chaouachi, Stephen S. Cheung, Hamdi Chtourou, Germina Cosma, Tadej Debevec, Matthew D. DeLang, Alexandre Dellal, Gürhan Dönmez, Tarak Driss, Juan David Peña Duque, Cristiano Eirale, Mohamed Elloumi, Carl Foster, Emerson Franchini, Andrea Fusco, Olivier Galy, Paul B. Gastin, Nicholas Gill, Olivier Girard, Cvita Gregov, Shona Halson, Omar Hammouda, Ivana Hanzlíková, Bahar Hassanmirzaei, Kim Hébert-Losier, Hussein Muñoz Helú, Tomás Herrera-Valenzuela, Florentina J. Hettinga, Louis Holtzhausen, Olivier Hue, Antonio Dello Iacono, Johanna K. Ihalainen, Carl James, Saju Joseph, Karim Kamoun, Mehdi Khaled, Karim Khalladi, Kwang Joon Kim, Lian-Yee Kok, Lewis MacMillan, Leonardo Jose Mataruna-Dos-Santos, Ryo Matsunaga, Shpresa Memishi, Grégoire P. Millet, Imen Moussa-Chamari, Danladi Ibrahim Musa, Hoang Minh Thuan Nguyen, Pantelis T. Nikolaidis, Adam Owen, Johnny Padulo, Jeffrey Cabayan Pagaduan, Nirmala Panagodage Perera, Jorge Pérez-Gómez, Lervasen Pillay, Arporn Popa, Avishkar Pudasaini, Alizera Rabbani, Tandiyo Rahayu, Mohamed Romdhani, Paul Salamh, Abu-Sufian Sarkar, Andy Schillinger, Heny Setyawati, Navina Shrestha, Fatona Suraya, Montassar Tabben, Khaled Trabelsi, Axel Urhausen, Maarit Valtonen, Johanna Weber, Rodney Whiteley, Adel Zrane, Yacine Zerguini, Piotr Zmijewski, Helmi Ben Saad, David B. Pyne, Lee Taylor, and Karim Chamari

Purpose: To investigate differences in athletes’ knowledge, beliefs, and training practices during COVID-19 lockdowns with reference to sport classification and sex. This work extends an initial descriptive evaluation focusing on athlete classification. Methods: Athletes (12,526; 66% male; 142 countries) completed an online survey (May–July 2020) assessing knowledge, beliefs, and practices toward training. Sports were classified as team sports (45%), endurance (20%), power/technical (10%), combat (9%), aquatic (6%), recreational (4%), racquet (3%), precision (2%), parasports (1%), and others (1%). Further analysis by sex was performed. Results: During lockdown, athletes practiced body-weight-based exercises routinely (67% females and 64% males), ranging from 50% (precision) to 78% (parasports). More sport-specific technical skills were performed in combat, parasports, and precision (∼50%) than other sports (∼35%). Most athletes (range: 50% [parasports] to 75% [endurance]) performed cardiorespiratory training (trivial sex differences). Compared to prelockdown, perceived training intensity was reduced by 29% to 41%, depending on sport (largest decline: ∼38% in team sports, unaffected by sex). Some athletes (range: 7%–49%) maintained their training intensity for strength, endurance, speed, plyometric, change-of-direction, and technical training. Athletes who previously trained ≥5 sessions per week reduced their volume (range: 18%–28%) during lockdown. The proportion of athletes (81%) training ≥60 min/session reduced by 31% to 43% during lockdown. Males and females had comparable moderate levels of training knowledge (56% vs 58%) and beliefs/attitudes (54% vs 56%). Conclusions: Changes in athletes’ training practices were sport-specific, with few or no sex differences. Team-based sports were generally more susceptible to changes than individual sports. Policy makers should provide athletes with specific training arrangements and educational resources to facilitate remote and/or home-based training during lockdown-type events.