Today\u2019s episode features JB莫林, who returns to the show after being guest #12, 3 years ago. JB is a world-leading researcher in the world of sprint biomechanics and forces, as well as resisted sprinting, force-velocity profiling and sprint injury factors. He is currently Full Professor at the Faculty of Sport Sciences of the University of Nice Sophia Antipolis (France). There he is a member of the Laboratory of Human Motor Function, Education Sport and Health. On our last podcast, JB went in depth into force-velocity profiling for sprinting, as well as the role of heavy sled sprint training and much more. JB is currently working to bring more clarity to the puzzle of sprint enhancement and hamstring injury prevention. As research is quickly shedding more light on various factors in human performance, especially in the sprint sector, I was excited to bring JB back for another show. On this episode, JB picks up where we left off, going over recent updates in sprint research and force velocity profiling. The main focus of this show is digging into sprint mechanics, fatigue, and hamstring injuries in sport. We\u2019ll also get into ideas on correlation vs. causation in interpreting statistics and research, as well as recent ideas on the role of the foot and ankle in sprint performance. Today\u2019s episode is brought to you by SimpliFaster, supplier of high-end athletic development tools, such as the Freelap timing system, kBox, Sprint 1080, and more. Key Points \u2022 What\u2019s new in resisted sprint training research over the last few years \u2022 Strength training in regards to the force velocity curve in sprinting \u2022 Correlation versus causation with strength training and sprinting ability \u2022 What are we seeing with sprint technique and hamstring injuries according to recent research \u2022 Core strength\/rotation and sprinting in regards to hamstring injury rates \u2022 The roles of fatigue in hamstring injuries \u2022 Recent research on the foot, ankle stiffness, injury and performance \u2022 Clarification of the causation\/correlation effects in jump tests and sprinting JB莫林 Quotes \u201cSprinting is catching up with the velocity based training that is well known in the gym\u201d \u201cWhen you sprint only once, then you cover the entire force velocity spectrum\u201d \u201cThere is not a lot of work published on how gym work influences sprinting force\/velocity profile\u201d \u201cDon\u2019t interpret transfer of training from correlations that are cross-sectional (correlation does not equal causation)\u201d \u201cIf you train a couple of school kids and they improve their level of strength and you assess that at the gym, yes they will improve their sprint times, but at some point you are not dealing with school kids anymore\u201d \u201cWe have some very high level rugby players tested, and there is no correlation between vertical F0 (equivalent of their 1RM in half squat) and their F0 in sprinting\u2026 there is no correlation in these trained people\u201d \u201cJumping shouldn\u2019t be the first information we collect if we are dealing with sprint people, it should be so obvious\u201d \u201cIt\u2019s easier to measure jumping variables in sprinters rather than sprint, and for that single reason in my opinion, we explain some of the misconception (why so many people want to use jumping as a sprint assessment or predictor)\u201d \u201cIt is much easier to measure your hamstring strength, rather than exploring and measuring and detailing your sprint technique\u201d \u201cI will name two (factors with sprint technique and hamstring injury) the first one is trunk lateral motion\u2026. Future injured players in rugby tended to have more lateral trunk flexion in swing phase\u2026. The core muscle activity (mainly trunk, glutes, superficial muscles) is clearly lower in soccer players who sustain a hamstring injury during the season when they sprint\u201d \u201cOne track research we have is around pelvic tilt angle, how your pelvis is tilted when you enter the swing phase of the sprint (is a risk factor)\u201d \u201cEvery PT knows that some very strong hamstring will be injured by the end of the season; some very weak hamstrings will not be injured by the end of the season\u201d \u201cYou see some situations of some people getting injured when they run straight ahead, and then they move their shoulder line and head to catch a pass or to see a colleague\u201d \u201cToday, almost 2020 there is no robot able to start from 0 on two legs, generate sprinting and acceleration at our human speeds, then slowing down and stopping. It\u2019s so complex it\u2019s very difficult to even modelize that and robotize that\u201d \u201cWhen you are fatigued, you push vertically when you accelerate\u201d Jean-Benoit (JB) Morin is currently Full Professor at the Faculty of Sport Sciences of the University of Nice Sophia Antipolis (France). He is a member of the Laboratory of Human Motor Function, Education Sport and Health. He obtained a Track & Field Coach National Diploma in 1998 and graduated in Sport Science at the University of Besan\u00e7on, France in 2000. He obtained his PhD in Human Locomotion and Performance in 2004 at the University of Saint-Etienne, France (Prof. Alain Belli), in collaboration with the University of Udine, Italy (Prof. Pietro diPrampero). He was an Assistant Professor at the Sport Science Department of the University of Saint-Etienne and member of the Laboratory of Exercise Physiology from 2005 to 2014. JB\u2019s field of research is mainly human locomotion and performance, with specific interest into running biomechanics and maximal power movements (sprint, jumps). He teaches locomotion and sports biomechanics, and strength training and assessment methods. He has published about 50 peer-review Journal articles since 2004. JB\u2019s main collaborations are with French sprinter Christophe Lemaitre and his group\/coach, and he is member of the French Soccer Federation research group, teaching professional coaches about sprint mechanics and training for acceleration. He also collaborates with New-Zealand professional and national rugby teams, and with professional soccer clubs in France and Spain. He practiced soccer in competition for 10 years, practiced and coached track and field (middle distance and 400m hurdles) for 8 years, and he is now enjoying trail running, road cycling and triathlon.