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Acceleration development #1: an ecological dynamics approach.

Updated: Feb 5, 2022

What does this even mean? In this post I will talk about what this means to me, how to plan a session, and some interesting challenges that have been thrown up while working to develop speed* within the context of the game. My current sport is rugby union, and I will talk about this idea in the context of rugby union.

*speed is a general term that consists of acceleration, transition and max velocity, but for this article, speed refers to acceleration capabilities.

This has been something we have been working on over the last number of weeks here in Hong Kong (since returning to training post lockdown), and I believe it is an important time to keep things contextual to maximise the time players have playing their sport or completing tasks that are representative of their sport as we had a short window before the domestic season resumes (<4 weeks).

An example of isolated acceleration work that I have implemented in the past. Completely unrepresentative of the game - no perception-action coupling, no challenge point, different surface etc. However, it still have a place in the development of athletes, as highlighted by Kyprianou et al. (2019) - although this paper was more in relation to maximal velocity.

Why develop speed "contextually"?

An interesting paper from Kyprianou et al. (2019) identified that players sprint faster in a sprint test in comparison to a game. This highlights the benefit of completing a sprint test to determine a player's max velocity. This I agree with. It would also make sense to suggest that in order to expose players to max velocity, they should sprint in a de-contextualised manner, with max speed training being shown to have a protective effect (Freeman et al., 2018).

However, this is typical of a siloed approach to player development, in my opinion. This approach, while being evidence based in preventing injuries and improving (sprint) performance, I do not believe it helps create a better player. When viewing speed as a skill, it is important that speed is trained as an emergent behaviour of the task in hand. Simple examples, if players are chasing back to make a tackle, they must run fast; if players want to put pressure on the attack, they must accelerate quickly off the line. They are not moving fast simply because they are told to, but they are moving fast because that's what the task demands from them.

It is a fine balance, and I do think there is a place for "isolated" speed exposure (an important place at that). But isolated speed exposure makes more robust players. Contextual speed exposure makes better players. Working with coaches to develop sessions that expose players to the stimulus they need, while also being representative of the sport they play is a vital part of athletic development. It is this particular aspect of my role, that I find most enjoyable - identifying performance solutions to performance problems.

What does contextual speed development look like?

As I dived into here, skill acquisition literature has very much guided my development in this space, an in particular the ecological dynamics framework. This framework is based on the original workings of James Gibson back in 1979, combining aspects of ecological psychology and dynamical systems theory. Ecological dynamics emphasise the learner-environment relationship, where learners need to attune to their environment and pick up relevant cues. With this framework, there are a number of key principles that must be included in any training session design to enhance speed in a contextual manner, all of which are interrelated.

1) Perception-Action / Information-Movement Coupling

We perceive to act and act to perceive. Players have decisions to make based on the information in front of them.

2) Representative Learning Design

The training environment needs to reflect the game environment, in particular the information used to guide actions on the field. Representative training design will help players become more attuned to relevant sources of information, to aid their decision making in a game.

3) Optimal Challenge Point (Guadagnoli & Lee, 2004)

The difficulty of the task should be representative of the game, but it should be at an optimal level which can promote decisive actions and the intent to move fast. Suitable task difficulty can provide the optimal balance between physical and cognitive performance. This is arguably one of the toughest challenges coaches face - to adapt training to meet the optimal challenge point of the individual players.

What learning opportunities does this produce?

Like many things, articulating a thought process is one thing, but practically applying that process is another.

Over the last number of weeks, our objective was to expose players to maximum intensity accelerations. Rather than simply placing players in a foot race against each other, we wanted to expose players to the maximum amount of rugby possible in the short preparation period in the lead up to the first domestic club game (4 week period), as mentioned previously. In essence, players completed a rugby session, and the main priority was to expose players to maximum accelerations.

While our aim was to expose players to maximal accelerations, it was likely that players would also get exposed to many other skills, both physical and technical. This is ok, as in a game, the skill of acceleration is never completed in isolation - instead it is an emergent behaviour from the performer-environment-task interaction. Depending on the group, the range of skills that could be trained in a contextual framework like this is dependent on the positional profile of the group. See below for the original outline that I shared with coaches, including a brief session plan. With all this in mind, unique challenges within sessions were presented.

Original session outline shared with our coaches.

Work to Rest ratio

With the session objective being max intensity speed, it is important to allow for suitable rest periods to allow players to reach their maximum intensity. In an isolated speed session, I would allow 1 minute rest for every 10m sprinted (10m sprint = 1 min rest; 30m sprint = 3 min rest). While this is unrealistic for a contextualised speed session, it is important that coaches allow for suitable rest periods, so we can chase the desired stimulus.

Suitable task difficulty

An identical session plan will produce two different outputs with different sets of players. This was shown when the exact same session was ran with the Outside 5 group and the Middle 5 group. As the session was more representative of what the Outside 5 do in a game, the challenge point from the session was optimal, and this allowed for a super high intensity (in this context high acceleration exposure, as measured on GPS). The challenge point exceeded the "optimal level" for many of the Middle 5 players, and this negatively affected their session intensity. The reduction in intensity was down to the fact that players had too many options (information overload) and this effected their ability to act with intent. Typically, this isn't an issue, and this presents a great opportunity for players to grow. However, we had a clear objective for our session.

The safe-uncertain quadrant for practice design.(McKay et al. 2020)

Defining the objective is also important - and this was something we had to come back to after our first session (see image below). If the objective is optimal skill adaptability, then a challenge point that causes uncertainty and reduces physical overload is perfectly fine. If the aim of the session is to create a physical stimulus, like maximal accelerations (as it was for our session), then a more simplified task design is likely to produce the desired effect. We wanted our activities to exist somewhere between the safe-certain quadrant and the safe-uncertain quadrant above.

Some of my reflections that I shared with our coaching staff after our first "contextual speed session". Typically, I would class this as the tail (sports science) wagging the dog (sport), but the context was unique as our players were essentially handed over to their clubs and we were doing the bare minimum - training what we felt players were not getting at club training. Have covered the names of players and coaches - all shared with permission.

As I said before, this problem is, for me, the most enjoyable part of coaching - the art. It can be like trying to balance on a knife-edge between technical difficulty to promote skill adaptation, and technical simplicity to promote physical overload. This is the ultimate challenge point for coaches (both sport and athletic development coaches): to design an environment that finds the optimal challenge point of the players they are working with, to achieve the objective they are striving for (i.e. learning a particular skill). If the objective changes, then it is also likely that the optimal environment (or part of that environment) will also change.

Players "out thinking" the drill

One drill was designed which required players to execute skills at maximum or near-maximum pace - in this case the technical skill was simply passing. Two attackers accelerated maximally (straight line sprint) from the try line, and after 22m, the ball was required to be passed from one player to the other. One defender (starting 2m further back from the attackers, positioned in between them) was tasked with intercepting the pass. After a number of reps, attacking players started to loop the pass over the defender to avoid the interception. Once this happened, the coach shouted, "that's not the drill!"

On reflection immediately after the session, the coach admitted that was poor coaching as he effectively criticised players for being creative, and finding a valid (in a game context) solution to the problem at hand. Instead of asking the players to simply not do something perfectly legal in the game, an alternative solution is to increase task difficulty. A couple of options could be that the defender starts further back from the attackers, or the attackers only have to accelerate 15m before passing (shortening the time the defender has to get back).

Training atypical scenarios

When working with a player group (T5 in this example), it would be easy to simply look at their most common occurrences in a game and just train that. But, similar to the Charlie Francis Vertical Integration method, where all elements are trained in different proportions throughout the year, all players on the field must be able to execute nearly all skills when the game goes to chaos (everything but set-piece and set-plays). For example, asking tight 5 player to play a 4v3 in a tight space is perhaps not something they would typically do in a game, but it could be a situation that they find themselves in, and therefore must be trained.

Getting a balance between suitable training activity design and contextualised development

Sticking with the same example, the training activity design in the 4v3 was in a very tight space, and this led to a high demands on technical skills and reading of the game in order to exploit the limited space on offer. The question was asked among the coaches if the space was too small, and if it was increased, would the contextual impact of the training activity have been lost? The conclusion from the coaching group was that the training activity space could have been increased slightly to allow for great acceleration exposure, but not a huge increase so not to lose the contextual link. This highlights the fine line between a contextual training activity and a decontextualised training activity.

Suitable Warm-Up

Is an isolated warm-up suitable for a contextualised session? The warm up I utilised was a combination of partner agility work and 10m races (isolated speed development). There was nothing representative of the game of rugby involved in the warm-up (although there was reading of other player's body shapes and movements in an attacking or defending agility sense). Feedback from one group of players after their session was that they were too slow to get to grips with the training activities prescribed. One reflection I had off the back of this is that perhaps the warm-up could be more contextualised to the game, and not just contextualised to human movement, to ensure that players are not "perceptually rusty" (a Tyler Yearby phrase; IG: @tyleryearby @emergence) when entering their training (main session) activities.


Contextualised speed development is not an easy thing to accomplish, and based on the evidence, isolated exposure to maximal speed exposure is still a beneficial supplement in the training diet. However, to maximise player preparation, I feel working closely with coaches to design suitable training sessions is an important part of athletic development, and an area I am keen to continue to develop. If I simply learn the basics of speed development, and don't work on developing the "skill" of speed within the context of the sport, I am doing the players and coaches a disservice, and I am only doing part of my job.

Special thanks to the coaches and players for their efforts throughout.


Freeman, Brock & Young, Warren & Smyth, Andrew & Talpey, Scott & Pane, Calvin & Carlon, Todd. (2018). The effects of sprint training and the Nordic hamstring exercise on eccentric hamstring strength and sprint performance in adolescent athletes. The Journal of sports medicine and physical fitness. 59.

Guadagnoli, Mark & Lee, Timothy. (2004). Challenge Point: A Framework for Conceptualizing the Effects of Various Practice Conditions in Motor Learning. Journal of motor behavior. 36. 212-24.

McKay, J., Davids, K., Robertson, S., & Woods, C. T. (2020). An Ecological Insight Into the Design and Integration of Attacking Principles of Play in Professional Rugby Union: A Case Example, International Sport Coaching Journal, , 1-6.

Kyprianou, Efthymios & Di Salvo, Valter & Lolli, Lorenzo & Al Haddad, Hani & Mendez-Villanueva, Alberto & Gregson, Warren & Weston, Matthew. (2019). To Measure Peak Velocity in Soccer, Let the Players Sprint. Journal of Strength and Conditioning Research.