Thanks for sticking with me.
What started as a short post on the toe-drag silliness, has somehow taken on a life of its own, and is now going on 10,000 words. Apologies – but I really think the context is required here; to unpack this properly, we need to peel back a few layers.
And don’t worry – we are almost done!!
Before moving on, I’d like to take a little time to better understand our ‘movement problem’, as it relates back to the 2nd post in this series, and how this relates to designing and implementing our training plans.
As a reminder, we communicate the movement problem as a ‘goal’, which in this case means an effective and efficient sprint performance – the ‘desired future’. Remember that goals drive actions; and actions are driven by a desired future state.
This sounds very simple, but many get lost at this initial stage: the goal is improved performance in the overall sprinting task – not improved performance of any of the factors that make up the sprint. Maximum strength, for example, may be an important factor in sprinting; but the development of maximum strength is not the goal – fast sprinting is! Similarly, the modification of any technical factor that makes up a sporting performance (for example, in this case the height of the heel recovery) is not the goal – fast sprinting is!
We must always begin with the problem – not the supposed solution to the problem; we do not begin with the ‘toe-drag solution’ we begin with the problem of effective and efficient acceleration.
JB Morin has offered a useful 5-step framework which outlines his, and his group’s research ‘problem-management’ process, which I have adapted somewhat, and outlined below to describe the process by which coaches can devise their technical models (and, to some extent, their training plans) as well as any variations to them based upon individual athlete characteristics.
Step 1: identify the task
Step 2: identify the primary KPIs (key performance indicators) of the task
Step 3: identify the underpinning physiological and biomechanical factors of the KPIs
Step 4: identify the underpinning, anthropometric and/or neuromuscular factors of the KPIs
Step 5: design, implement, and measure the training content and effects, asking in order:
- Does the training content improve the key anthropometric and neuromuscular abilities as defined in step 4?
- Does improving these key abilities improve the physiological and biomechanical factors defined in step 3?
- Does improving these physiological and biomechanical factors improve the primary KPIs defined in step 2?
- Does improving these KPIs improve the performance of the task, as identified in step 1?
Step 6: repeat this loop
Let’s go through this in order, as it relates to block clearance and initial acceleration. Please note that while I present this framework here as a hierarchy, all of these steps are interrelated, where this is top-down and bottom-up influences.
STEP 1: TASK IDENTIFICATION
In this case, we cannot be distracted by components of the task (e.g. block clearance, ‘drive phase’, etc.). The task is simply the distance from which a sprinter starts to when she finishes (e.g. 60m, 100m, 200m,). For our purposes, we are assuming the 100m sprint race.
STEP 2: KPI IDENTIFICATION
My friend Dr. Fergus Connolly, in his excellent book Game Changer: the art of sport science, outlines the ‘Four-Coactive Model’ – the four interdependent elements of player preparation. They are called ‘coactives’ because they both complement and rely upon each other. These four coactives come together in a synchronized manner in order for the player to execute effectively. They cannot exist without each other. They are complementary, codependent, and co-reliant, and allow us to better identify the primary KPIs. These four coactives are:
All four elements are present to varying degrees in every moment of practice, preparation, and competition. Following, I will give examples of how we use these four coactives to identify our primary KPIs:
When it comes to block clearance and initial acceleration, the tactical KPI can be to either ‘generate as much horizontal velocity as possible as quickly as possible’; or, ‘accelerate as efficiently as possible in order to maximize peak velocity’ – i.e. a deep, and patient acceleration, thereby reducing effects of late-race deceleration.
I bias towards the latter tactic, but if an athlete is an incredible starter, and lacks superior peak velocity, then an appropriate tactical KPI might be to get as far out in front as possible through the acceleration, and try to hang on.
Coach Vince Anderson describes the tactical motivation of the start as “aggressively pushing into a tall running posture”. Similarly, Coaches Dan Pfaff, Tom Tellez, and others have approached their tactical consideration of the start in this same way.
As with all KPIs, however, tactics are both task- and athlete-dependant. Not all athletes will fit into this model, which is something we will speak to in the next part of this series.
The technical KPIs are dependent upon the tactical KPIs; if the tactical KPIs include a deep and patient acceleration, then the technical KPIs must support this. I speak to the athletes I coach about a patient, rhythmical rise of their center of mass over time – as if they were a plane taking off from a runway. Understand, however, that not all athletes are 747s – some are small, propeller-driven Cessnas, who will thus rise much quicker, as they lack the power abilities to accelerate deeply.
If we compare the acceleration pattern of a young athlete to that of an elite athlete, for example: the elite athlete will have a much faster maximum velocity, will take far longer to reach it, and therefore, the acceleration will be longer, and deeper. The developing athlete will reach maximum velocity much sooner, and thus the acceleration will be shorter. That said – the principles are the same:
- Maximal projection of the center of mass
- Rise the center of mass with every step
- Increase the rhythm with every step (the confluence of stride frequency and ground contact time)
However, if the tactical KPI suggests a faster initial acceleration, then the technical KPIs must support it: for example, perhaps a lower heel recovery, and incomplete hip and knee extension may be appropriate for this tactic (although not necessarily – more to come on this later!).
A patient acceleration requires psychological composure, whereby the athlete ‘stays in their lane’, and isn’t distracted by competitors. We often observe, for example, an athlete ‘rush’ their acceleration if they have had a poor reaction to the gun. More experienced athletes – or athletes who have better stabilized their technical and tactical KPIs – will generally not react to their competitors, and will instead focus intently on their own plans. This video of the 1991 World Championships is one of my favorite examples of this. Carl Lewis reacted poorly, and was seemingly out of the race, but he ‘stayed in his lane’, and went on to win, setting a world record in the process.
As I wrote, all four coactives are inter-related, and it is no different with the physiological KPIs, which must appropriately support the technical and tactical KPIs. For example, an athlete who lacks the underpinning physiological force-producing abilities required to accelerate deeply should not attempt to falsely do so. Examples of this are frequent – especially with developing athletes who try to ‘stay low’ for too long, and thereby compromise their peak velocity.
The role and relevance of maximal strength to the expression of speed is another article in and of itself, but, needless to say, it is a factor all coaches must contend with. While it is an extremely complex topic, a key heuristic is “the faster the athlete, the less relevant is maximum strength”.
I will discuss this in a little more detail later in the series.
STEP 3: PHYSIOLOGICAL AND BIOMECHANICAL FACTOR IDENTIFICATION
The main question here is: what are the primary determinants of sprint performance and what are the underlying modifiable physiological factors?
As a refresher from Part I, a key biomechanical demand of the block start and initial acceleration is that the athlete projects their body (Center of Mass) up and out in a manner that allows them to successfully execute the subsequent steps.
From a kinetics (force) standpoint, this requires:
- Sufficient vertical force to support and lift the body
- Large amounts of horizontal force to propel the body forward
Athletes lacking the requisite ability to rapidly generate and apply these forces may not be able to achieve the desired shapes, and, therefore, velocities.
These shapes are defined by the following six technical factors:
- Acute forward body angle, with COM in front of the stance-leg foot for the majority of stance phase
- Forceful flexion of the swing-leg thigh and simultaneous forceful extension of thestance-leg thigh
- Initial ground contact occurring under or behind the COM
- Relatively stiff ground contact on the ball of foot to allow for effective force transmission
- The arms flex and extend to counterbalance the legs
- The head in alignment with the torso
In addition, we will expect that elite sprinters will move between these shapes at a greater velocity than slower athletes; they will generally reposition their limbs in space faster, as well as get off the ground faster.
From a physiological standpoint, the ability to accomplish the above demands typically requires the following three factors:
- High percentage of fast-twitch muscle fiber
- Neuromuscular coordination and control
- Adequate ratio of strength and power to body mass
As all the cooactives are codependent, the physiological and biomechanical factors here will influence the tactical and technical factors mentioned earlier.
STEP 4: ANTHROPOMETRIC AND-OR NEUROMUSCULAR FACTOR IDENTIFICATION
Understanding which anthropometric and/or neuromuscular factors are modifiable, and to what degree they can affect performance is a challenging proposition for all coaches and scientists.
For example, joint mobility and muscular flexibility are two factors that many coaches try to affect, with the assumption that increased mobility and flexibility will lead to improved performance. However, as with most factors, there is a ‘Goldilocks effect’ where both too little and too much can lead to decreased performance. Rather, we look for an appropriate level of each, allowing the athlete to accomplish the task specific to their individual structural constraints at the current time (their ‘intrinsic dynamics’).
Other anthropometric and/or neuromuscular factors that play a role in acceleration performance include, but is not limited to:
- Muscle physiological cross-sectional area
- Body composition
- Fascicle length and pennation angles of muscular tissue
- Tendon and joint stiffness
All of these factors are modifiable to a degree, and our challenge as coaches is to know which ‘buttons to press’, how and when to press them, and how any modification of single factors affects performance. In many cases, this can be a bit of a ‘trial and error’ process, so we should be careful not to modify too many factors simultaneously – especially without access to precise sport science support.
Of course, both body composition and muscle pCSA can be modified quite easily and safely, but many of the other factors are significantly more complex, and have less-obvious knock-on effects on other factors.
As it relates to block clearance and initial acceleration, one neuromuscular factor we discuss quite often is the ‘stiffness’ of the knee and ankle joints as the body rotates over the foot during ground contact. The codependency of neuromuscular and technical factors is clear to see here – as effective stiffness relies significantly on the position (related to the body’s COM) and the direction of force application upon touch-down. What we look for here is a stable knee through the entirety of the ground-contact phase, and a minimal heel drop from initial touch-down down through to toe-off.
STEP 5: DESIGN, IMPLEMENT, AND TEST
Finally, we can design and implement a training plan (our ‘experiment’), and more specifically, our technical model, testing the relationships between each step outlined above, and making adjustments to our plan as we continue to iterate upon these steps.
Hopefully, the preceding has given you a brief overview of how I go about defining the problem, and the steps I take to implement a technical model. However, this only gives us a starting point.
George Box famously stated “All models are wrong; some are useful”, and in part V, I will expand upon this initial framework, and discuss how we better-individualize both the technical model and the training plan. I hope then to finally bring it all together, discussing practical take-homes coaches can use to teach effective and efficient block clearance and acceleration!
Thanks for reading,
*thanks to Ken Clark and Kebba Tolbert for the feedback with this section!