Johan LahtiUniversité Côte d'Azur · Laboratoire Motricité Humaine, Education, Sport, Santé (LAMHESS)
Johan Lahti
Doctor of Philosophy
About
26
Publications
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Citations since 2017
Introduction
Publications
Publications (26)
The aim of this study was to analyse the influence of fatigue on sprint biomechanics. Fifty-one football players performed twelve maximal 30 m sprints with 20 s recovery between each sprint. Sprint kinetics were computed from running speed data and a high-frequency camera (240 Hz) was used to study kinematic data. A cluster analysis (K-mean cluster...
Despite efforts to intervene, hamstring muscle injuries (HMI) continue to be one of the largest epidemiological burdens in professional football. The injury mechanism takes place dominantly during sprinting, but also other scenarios have been observed, such as overstretching actions, jumps, and change of directions. The main biomechanical roles of...
The aim of this pilot study was to analyze the potential association of a novel multifactorial hamstring screening protocol with the occurrence of hamstring muscle injuries (HMI) in professional football. 161 professional male football players participated in this study (age: 24.6 ± 5.36 years; body-height: 180 ± 7.07 cm; body-mass: 77.2 ± 7.70 kg)...
Clear decreases in horizontal force production capacity during sprint acceleration have been reported after hamstring injuries (HI) in football players. We hypothesized that lower FH0 is associated with a higher HI occurrence in football players. We aimed to analyze the association between sprint running horizontal force production capacities at lo...
To train hamstring muscle specifically to sprint, strengthening programs should target exercises associated with horizontal force production and high levels of hamstring activity. Therefore, the objectives of this study were to analyze the correlation between force production capacities during sprinting and hamstring strengthening exercises, and to...
Background
Sprint performance is an essential skill to target within soccer, which can be likely achieved with a variety of methods, including different on-field training options. One such method could be heavy resisted sprint training. However, the effects of such overload on sprint performance and the related kinetic changes are unknown in a prof...
Introduction
Hamstring muscle injuries (HMI) continue to plague professional football. Several scientific publications have encouraged a multifactorial approach; however, no multifactorial HMI risk reduction studies have been conducted in professional football. Furthermore, individualisation of HMI management programmes has only been researched in...
We tested the hypothesis that the degree of adaptation to highly focused sprint training at opposite ends of the sprint Force-Velocity (FV) spectrum would be
associated with initial sprint FV-profile in rugby athletes. Training-induced changes
in sprint FV-profiles were computed before and after an 8-week in-season resisted
or assisted sprint train...
Sprint performance is an essential skill to target within soccer. However, time-consuming intervention models could be easily rejected by coaches. Therefore, alternative and efficient field training options are warranted. One such method could be heavy resisted sprint training. However, it is unknown whether such overload will be efficient in assis...
Background: In the bilateral Nordic hamstring exercise (NHE), hamstrings operate at relatively short lengths, which may limit this exercise’s efficacy in hamstring injury prevention.
Objectives: To examine knee flexion torque, and biceps femoris long head (BFlh) and semitendinosus (ST) high-density electromyography (HD-EMG) activity during unilate...
The primary means for disseminating sport and exercise science research is currently through journal articles. However, not all studies, especially those with null findings, make it to formal publication. This publication bias towards positive findings may contribute to questionable research practices. Preregistration is a solution to prevent the pub...
Different stance widths are commonly utilized when completing the barbell back squat during athletic general preparedness training. Width manipulation is thought to influence sagittal plane stimuli to the hip and knee extensors, the primary extensor musculature in the squat. However, how width manipulation affects frontal plane stimuli is less unde...
Modern team sport context is associated with both hightraining and games demands, and consequently high in-jury rates. Thus, reducing injuries is key for performance,health and economical reasons. For example, the training,research and medical communities are dedicated to better un-derstand and thus prevent or at least reduce the number ofhamstring...
Aim: Hamstring muscle injury is the main injury related to sports requiring sprint acceleration. In addition, hamstring muscles have been reported to play a role in horizontal force production during sprint acceleration performance. The aim of the present study was to analyze (i) the determinants of horizontal force production and (ii) the role of...
Heavy barbell back squatting is commonly seen as an essential general preparedness exercise for the hip and knee extensors[1]. Posited as a functional exercise, it encompasses similar kinematics to many athletic movements, including acceleration and change of direction. Moreover, anecdotes argue that a narrower squat stance is more transferable to...
Nordic hamstring exercise torque and sprint acceleration mechanical profile and performance in team sport athletes; are they related?
Authors: Lahti J, Giacomo J-P, Gerus P, Noulé T, Hegyi A, Morin J-B
Introduction
The hamstring muscle groups functional status is considered essential for sprint performance [1]. The Nordic Hamstring Exercise (NHE) h...
ECSS 2018 Dublin 05.07.2018 - 18:00 - 19:30, Lecture room: WICKLOW MEETING ROOM 2
INTRODUCTION:
Nordic hamstring exercise (NHE) is a popular injury prevention and rehabilitation exercise. Conventionally, NHE is performed bilaterally and with extended hip joint, i.e. at a relatively short muscle length. According to Askling et al. (2013), exercises...
Aims
In the current study we investigated the effects of resisted sprint training on sprinting performance and underlying mechanical parameters (force-velocity-power profile) based on two different training protocols: (i) loads that represented maximum power output (Lopt) and a 50% decrease in maximum unresisted sprinting velocity and (ii) lighter...
Spreadsheet for optimal loading computation.
(XLSX)
Complementary methodological considerations.
(DOCX)
Questions
Questions (2)
Hey guys! Looking for some statistical advice to anticipate review response.
I have done an intervention with 3 groups, 2 of which are in the intervention and 1 that is control. The 2 intervention groups are completeing sled training to potentially increase sprint performance, but they only differ with training load (heavy vs very heavy). The control group continues with normal practice (another team within the same pro soccer league that does not use systematic acceleration training).
All groups have been divided evenly so that initial sprint performance (mean + CI) is similar, therefore we are using pre sprint performance as a covariate in the ANCOVA. There is only one factor (one time point), therefore One-way.
One of my study questions is whether training with heavy sleds is better than doing nothing concrete (i.e. non systematic acceleration training). Therefore, my question is, would it be statistically appropriate to pool the heavy and very heavy sled groups to answer this question, also considering sample size is only 9 (sled 1) + 9 (sled 2) + 10 (control).
The second study question is whether heavy or very heavy worked better, where a simple independant t-test will suffice.
Opinions?
Thanks for all the help!
Hey guys!
Im interest in looking into the possible amplified stimuli we can get from ballistic training via the eccentric or absorption phase. If you know of any good studies that report loaded jump squat/olympic lift absorption external/interal kinetics then please do share. Also keen to see what people think of using ballistic training as a possible strength training modality with an increased mechanical power element.
