Jean-Benoît Morin on speed assessment and training

As football gets ever faster and the physical demands of the game increase, devastating speed has become a formidable weapon for top players. In this session for the Science Explained series, Jean-Benoît Morin of Jean Monnet University in St Etienne, France, reveals the hidden factors determining sprint performance, and explores how coaches can design training programmes to help players develop this crucial attribute. The session is followed by an in-depth Q&A, hosted by FIFA’s Professor Paul Bradley.

Explain the physics that determines sprint performance.
Suggest ways of measuring sprint performance in the laboratory and on the pitch.
Examine how coaches can improve performance by combining hard data with an understanding of the mechanics of sprinting.

Effective sprinting comes down to a combination of mechanics (the ability to generate power) and kinematics (how well you can transmit that power to the ground).
These factors are heavily influenced by key muscle groups, which can be trained.
Players cover distance in different ways, so advanced sprint coaching requires a tailored approach.

Practitioners can estimate sprint performance using mathematical equations, even if they do not have the facilities to measure it precisely.
Coaches should aim to optimise running style at the same time as training relevant muscle groups. Doing so is likely to improve performance and reduce injuries.
Especially when working with established elite players, try to work out which “zones” of the player’s sprint curve can be improved, and train specifically for those zones.

Welcome by Professor Paul Bradley

Part 1: How to measure sprinting

Part 2: Kinetics and kinematics

Part 3: Introducing the sprint spectrum

Part 4: How to train the spectrum

Part 5: Does sprinting cause injuries?

Part 6: The puzzle of injury prevention

Part 7: Q&A

Part 1: How to measure sprinting
Sprint performance ultimately comes down to two factors: kinetics (the ability to generate force) and kinematics (the ability to transmit that force efficiently to the ground). Measuring these two factors outside the laboratory is difficult, but performance can be estimated very reliably based on position or speed measurement over time. It is important to highlight that these measurements come with a caveat for football coaches: most runs made on a football pitch are curved, not straight. The tighter the curve, the slower you have to run.

Part 2: Kinetics and kinematics
Most of the power needed for sprinting comes from the hip extensors, ankle plantar flexors and feet; one Australian study found that up to 75% of the mechanical work to generate acceleration is done by those muscle groups. All other things being equal, strengthening those muscles should improve sprint performance. However, that training will only be effective if players can put that extra power down into the ground. To do that, they need to optimise the kinematics of their sprinting action, a process that requires detailed video analysis.

The physics of sprinting

Part 3: Introducing the sprint spectrum
So, how exactly should practitioners coach sprinting? Training beginners is relatively easy: the more they sprint, the better they get. With older players, a more tailored approach is needed. Athletes sprint in very different ways: some are explosive out of the blocks, while others are strong at the end of a sprint. The challenge for coaches is to work out which points on a player’s “sprint spectrum” can be improved, and target them accordingly.

Part 4: How to train the spectrum
This poses the question of how to train specific zones on the sprint spectrum. As Professor Morin demonstrates, this can be done using tailored resistance training. The aim of this approach is to keep players in the specific zone of the sprint spectrum that they need to work on. For resistance training to be effective, it is crucial to set resistance individually as a percentage of velocity decrement, rather than body mass. This is because two players of the same weight can have very different sprint profiles.

Two very different sprint profiles

Part 5: Does sprinting cause injuries?
Football is getting faster, and overall injury rates are the same or worse now than they were 30 years ago. However, that average masks excellent injury records at some clubs. In this part of his presentation, Professor Morin dives into the data to find out exactly how these clubs are preventing injuries, and suggests that overall strain plays a bigger role in injuries that sprint exposure alone. Luckily for club medical personnel, that strain can be reduced by good running technique.

Part 6: The puzzle of injury prevention
Some injuries are inevitable, but coaches can take action to make the avoidable ones less likely. Recent research suggests that two specific factors can have a significant impact on hamstring injury rates. One is the maximum force output of the knee flexors when sprinting; lower outputs are associated with more injuries. The other is the ability to control the movements of the pelvic region. To conclude the session, Professor Morin shows how changing a player’s running pattern and improving their pelvic control might reduce mechanical strain, and their injury risk.

00:19
During the season, how can high-speed running in training help to reduce injury risk in players?

03:07
Which gym-based strategies are most helpful in preventing soft-tissue injuries?

05:05
Which exercises are best for improving lumbar/pelvic control?

07:14
Should players new to sprint training focus more on sprint volume or on sprint technique?

09:11
A lot of people think sprinting always requires 100% effort. Can sub-maximal training provide the same benefits as training at 100%, and reduce injury risk at the same time?

11:56
Why is additional sprint training needed at all, given that players are exposed to plenty of sprinting during matches?

14:10
We talk a lot in these sessions about developing young players. How would you modify sprint training for young players as opposed to older ones?

15:48
How can practitioners make time for sprint-based injury prevention work, given the constraints they face?

18:28
In football, the demands on players are dependent on positions and tactical roles. How should positional differences in sprint demand influence training and injury-prevention strategies?

21:15
We know that 70 – 80% of sprints in football are curvilinear, not in a straight line. How can we prepare players for this kind of sprint work during games?

24:31
What are your take-home messages for practitioners from today’s presentation?

Jean-Benoît (JB) Morin is a Professor at Jean Monnet University in Saint-Etienne (France), where he is Director of the Sports Science Department and a member of the Inter-University Laboratory of Human Movement Biology (LIBM). JB’s primary field of research is human locomotion and performance, with a particular interest in running biomechanics and maximal-power movements like sprint and jumps. He edited the textbook Biomechanics of Training and Testing (2018) and has published over 180 peer-reviewed scientific papers. He also works as a consultant for professional athletes and sport organisations in various sports, including football.