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Can We Modify Maximal Speed Running Posture? Implications for Performance and Hamstring Injury Management

Jurdan Mendiguchia, Adrián Castaño-Zambudio, Pedro Jiménez-Reyes, Jean–Benoît Morin, Pascal Edouard, Filipe Conceição, Jonas Tawiah-Dodoo, and Steffi L. Colyer

Purpose: Sprint kinematics have been linked to hamstring injury and performance. This study aimed to examine if a specific 6-week multimodal intervention, combining lumbopelvic control and unning technique exercises, induced changes in pelvis and lower-limb kinematics at maximal speed and improved sprint performance. Methods: Healthy amateur athletes were assigned to a control or intervention group (IG). A sprint test with 3-dimensional kinematic measurements was performed before (PRE) and after (POST) 6 weeks of training. The IG program included 3 weekly sessions integrating coaching, strength and conditioning, and physical therapy approaches (eg, manual therapy, mobility, lumbopelvic control, strength and sprint “front-side mechanics”-oriented drills). Results: Analyses of variance showed no between-group differences at PRE. At POST, intragroup analyses showed PRE–POST differences for the pelvic (sagittal and frontal planes) and thigh kinematics and improved sprint performance (split times) for the IG only. Specifically, IG showed (1) a lower anterior pelvic tilt during the late swing phase, (2) greater pelvic obliquity on the free-leg side during the early swing phase, (3) higher vertical position of the front-leg knee, (4) an increase in thigh angular velocity and thigh retraction velocity, (5) lower between-knees distance at initial contact, and (6) a shorter ground contact duration. The intergroup analysis revealed disparate effects (possibly to very likely) in the most relevant variables investigated. Conclusion: The 6-week multimodal training program induced clear pelvic and lower-limb kinematic changes during maximal speed sprinting. These alterations may collectively be associated with reduced risk of muscle strain and were concomitant with significant sprint performance improvement.

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Running Mechanics During the World’s Most Challenging Mountain Ultramarathon

Francis Degache, Jean-Benoît Morin, Lukas Oehen, Kenny Guex, Guido Giardini, Federico Schena, Guillaume Y. Millet, and Grégoire P. Millet

The aim of study was to examine the effects of the world’s most challenging mountain ultramarathon (Tor des Géants [TdG]) on running mechanics. Mechanical measurements were undertaken in male runners (n = 16) and a control group (n = 8) before (PRE), during (MID), and after (POST) the TdG. Contact (t c) and aerial (t a) times, step frequency (f), and running velocity (v) were sampled. Spring-mass parameters of peak vertical ground-reaction force (F max), vertical downward displacement of the center of mass (Δz), leg-length change (ΔL), and vertical (k vert) and leg (k leg) stiffness were computed. Significant decreases were observed in runners between PRE and MID for t a (P < .001), F max (P < .001), Δz (P < .05), and k leg (P < .01). In contrast, f significantly increased (P < .05) between PRE and MID-TdG. No further changes were observed at POST for any of those variables, with the exception of k leg, which went back to PRE. During the TdG, experienced runners modified their running pattern and spring-mass behavior mainly during the first half. The current results suggest that these mechanical changes aim at minimizing the pain occurring in lower limbs mainly during the eccentric phases. One cannot rule out that this switch to a “safer” technique may also aim to anticipate further damages.

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Validity of a Simple Method for Measuring Force-Velocity-Power Profile in Countermovement Jump

Pedro Jiménez-Reyes, Pierre Samozino, Fernando Pareja-Blanco, Filipe Conceição, Víctor Cuadrado-Peñafiel, Juan José González-Badillo, and Jean-Benoît Morin

Purpose:

To analyze the reliability and validity of a simple computation method to evaluate force (F), velocity (v), and power (P) output during a countermovement jump (CMJ) suitable for use in field conditions and to verify the validity of this computation method to compute the CMJ force–velocity (Fv) profile (including unloaded and loaded jumps) in trained athletes.

Methods:

Sixteen high-level male sprinters and jumpers performed maximal CMJs under 6 different load conditions (0–87 kg). A force plate sampling at 1000 Hz was used to record vertical ground-reaction force and derive vertical-displacement data during CMJ trials. For each condition, mean F, v, and P of the push-off phase were determined from both force-plate data (reference method) and simple computation measures based on body mass, jump height (from flight time), and push-off distance and used to establish the linear Fv relationship for each individual.

Results:

Mean absolute bias values were 0.9% (± 1.6%), 4.7% (± 6.2%), 3.7% (± 4.8%), and 5% (± 6.8%) for F, v, P, and slope of the Fv relationship (SFv ), respectively. Both methods showed high correlations for Fv-profile-related variables (r = .985–.991). Finally, all variables computed from the simple method showed high reliability, with ICC >.980 and CV <1.0%.

Conclusions:

These results suggest that the simple method presented here is valid and reliable for computing CMJ force, velocity, power, and Fv profiles in athletes and could be used in practice under field conditions when body mass, push-off distance, and jump height are known.

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Mechanical Properties of Sprinting in Elite Rugby Union and Rugby League

Matt R. Cross, Matt Brughelli, Scott R. Brown, Pierre Samozino, Nicholas D. Gill, John B. Cronin, and Jean-Benoît Morin

Purpose:

To compare mechanical properties of overground sprint running in elite rugby union and rugby league athletes.

Methods:

Thirty elite rugby code (15 rugby union and 15 rugby league) athletes participated in this cross-sectional analysis. Radar was used to measure maximal overground sprint performance over 20 or 30 m (forwards and backs, respectively). In addition to time at 2, 5, 10, 20, and 30 m, velocity-time signals were analyzed to derive external horizontal force–velocity relationships with a recently validated method. From this relationship, the maximal theoretical velocity, external relative and absolute horizontal force, horizontal power, and optimal horizontal force for peak power production were determined.

Results:

While differences in maximal velocity were unclear between codes, rugby union backs produced moderately faster split times, with the most substantial differences occurring at 2 and 5 m (ES 0.95 and 0.86, respectively). In addition, rugby union backs produced moderately larger relative horizontal force, optimal force, and peak power capabilities than rugby league backs (ES 0.73−0.77). Rugby union forwards had a higher absolute force (ES 0.77) despite having ~12% more body weight than rugby league forwards.

Conclusions:

In this elite sample, rugby union athletes typically displayed greater short-distance sprint performance, which may be linked to an ability to generate high levels of horizontal force and power. The acceleration characteristics presented in this study could be a result of the individual movement and positional demands of each code.

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Assessing Horizontal Force Production in Resisted Sprinting: Computation and Practical Interpretation

Matt R. Cross, Farhan Tinwala, Seth Lenetsky, Scott R. Brown, Matt Brughelli, Jean-Benoit Morin, and Pierre Samozino

The assessment of horizontal force during overground sprinting is increasingly prevalent in practice and research, stemming from advances in technology and access to simplified yet valid field methods. As researchers search out optimal means of targeting the development of horizontal force, there is considerable interest in the effectiveness of external resistance. Increasing attention in research provides more information surrounding the biomechanics of sprinting in general and insight into the potential methods of developing determinant capacities. However, there is a general lack of consensus on the assessment and computation of horizontal force under resistance, which has resulted in a confusing narrative surrounding the practical applicability of loading parameters for performance enhancement. As such, the aim of this commentary was twofold: to provide a clear narrative of the assessment and computation of horizontal force in resisted sprinting and to clarify and discuss the impact of methodological approaches to subsequent training implementation. Horizontal force computation during resisted sleds, a common sprint-training apparatus in the field, is used as a test case to illustrate the risks associated with substandard methodological practices and improperly accounting for the effects of friction. A practical and operational synthesis is provided to help guide researchers and practitioners in selecting appropriate resistance methods. Finally, an outline of future challenges is presented to aid the development of these approaches.

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Training Periodization Over an Elite Rugby Sevens Season: From Theory to Practice

Bruno Marrier, Yann Le Meur, Cédric Leduc, Julien Piscione, Mathieu Lacome, Germain Igarza, Christophe Hausswirth, Jean-Benoît Morin, and Julien Robineau

Purpose: To describe the training periodization in rugby sevens players competing in the World Rugby Sevens Series during a non-Olympic season. Methods: Workload data were collected over a 33-wk period in 12 male players participating in a full competitive season. Workload was quantified using session rating of perceived exertion and global positioning system–derived data during training and competition. Self-reported well-being was assessed using a questionnaire. Each variable was analyzed weekly and through 5 mesocycles (preseason, in-season 1–4), each of which ended with competition blocks. Results: The perceived load decreased throughout the season for the full squad (−68% [26%] between preseason and final competitive block, large effect) and when unavailable players were removed from the analysis (−38% [42%], moderate). Weekly perceived load was highly variable, with a typical periodization in 4 phases during each mesocycle (regeneration, training overload, taper, and competition). During the preseason, the workload was higher during the overload training phase than during the competitive period (range: +23% to +59%, large to very large, for the distance covered above individual maximal aerobic speed and the number of accelerations). This observation no longer persisted during the season. The well-being score decreased almost certainly from in-season 3 (moderate). Conclusions: These results highlighted the apparent difficulty in maintaining high-load training periods throughout the season in players engaged on the World Rugby Sevens Series despite ∼4–7 training weeks separating each competitive block. This observation was likely explained by the difficulties inherent to the World Rugby Sevens Series (risk of contact injury, calendar, and multiple long-haul travel episodes) and potentially by limited squad-rotation policies.

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Preconditioning Strategy in Rugby-7s Players: Beneficial or Detrimental?

Bruno Marrier, Alexandre Durguerian, Julien Robineau, Mounir Chennaoui, Fabien Sauvet, Aurélie Servonnet, Julien Piscione, Bertrand Mathieu, Alexis Peeters, Mathieu Lacome, Jean-Benoit Morin, and Yann Le Meur

Purpose: Preconditioning strategies are considered opportunities to optimize performance on competition day. Although investigations conducted in rugby players on the effects of a morning preconditioning session have been done, additional work is warranted. The aim of this study was to monitor changes in physical and psychophysiological indicators among international Rugby-7s players after a priming exercise. Methods: In a randomized crossover design, 14 under-18 international Rugby-7s players completed, at 8:00 AM, a preconditioning session consisting of a warm-up followed by small-sided games, accelerations, and 2 × 50-m maximal sprints (Experimental), or no preloading session (Control). After a 2-h break, the players performed a set of six 30-m sprints and a Rugby-7s match. Recovery–stress state and salivary stress-marker levels were assessed before the preloading session (Pre), immediately after the preloading session (Post 1), before the testing session (Post 2), and after the testing session (Post 3). Results: Experimental–Control differences in performance across a repeated-sprint test consisting of six 30-m sprints were very likely trivial (+0.2, ±0.7%, 3/97/1%). During the match, the total distance covered and the frequency of decelerations were possibly lower (small) in Experimental compared with Control. Differences observed in the other parameters were unclear or possibly trivial. At Post 2, the perceived recovery–stress state was improved (small difference) in Experimental compared with Control. No difference in salivary cortisol response was observed, while the preconditioning session induced a higher stimulation of salivary testosterone and α-amylase. Conclusions: The players’ ability to repeat sprints and physical activity in match play did not improve, but their psychophysiological state was positively affected after the present preconditioning session.