Using an ecological dynamics framework to coach defence

Using the example of an U15s team, here’s how I would use a constraints-led approach underpinned by ecological dynamics.

As a lecturer in Sport Coaching and PE at Sheffield Hallam University, and through my role as a PhD researcher, I’ve been researching ecological dynamics and through a project with the RFU. I’ve been able to experiment with various teams and this is how I’d approach defence with a U15s team.

If you’ve been working with a team for a while, you will have some idea of what their strengths and weaknesses are. I want to allow the players to recognise what those are for themselves and then use that to build some principles.


Ask the players what they think are the key principles of defence for them (principles of attack and defence exist together and should be trained together). They will use their own language, which might be a mix of what they understand and what they think they understand. For example, they might say line speed is good. You need to ask them what that means to them. It is key to get an insight into what they see in games, what lens they are looking through. This can then help us as a coach when designing training sessions.

Representative co-design means the coach and players create the session’s elements together. Mainly the players help with the manipulation of constraints during training. Again, this does depend on the experience of your players.

For less experienced players, you will have more input. However, they still need to have some say. The key here is that the training is developed through their lens. In other words, what they see, how they talk about the game, and how they perform. It also helps you develop the players at a rate that’s appropriate for them.

Representative means that training looks, to a certain extent, like the game. With tackling and defence, we can’t jump straight into full contact. Nor is it practical or possible to play 15 v 15. Your sessions should have clear links to match situations, it needs to represent the U15s game that they play.


  • Affordances: opportunities for action, though they don’t have to be taken. For example, reducing the number of defenders gives the attacking team different spaces to attack.
  • Principles: an idea that explains how something happens. For example, in defence, a principle is go forward, because you then cut down the time and space for the attack.
  • Representative co-design: the players and coaches adjust the session’s elements to match their needs and the needs of the game they are playing.
  • Constraints: these are split into three main areas: task, individual and environment. These modify the movement patterns of the player. For example, rules, skills and the weather are constraints.
  • Self-organise: the players find solutions to game problems, rather than be given explicit instructions on how to solve them.


When a player identifies a principle, you want to understand what they mean and then how they will apply that principle. For example, if they think that pressure is a key principle, how will they put pressure on the attack? Then, does it suit their style of play? Are they good tacklers? Then, they need to apply that principle in the context of what the attack might do.


The principles will create affordances and they will allow the players to work together and self-organise as a collective unit. The principles will also allow coaches to design training sessions.
An affordance is an opportunity for action. The player may not take the opportunity, but it is an option which has consequences.

To self-organise means (and we have to remember that it is tricky to define), where the players work out how to solve a game problem without an explicit plan, leading to a coordinated behaviour, or inter-team co-ordinated variable.


Training then works on helping the team self-organise and how they see different affordances and then act on them as individuals and as a team.

In other words, you put conditions into the practice. In a defence training session, let’s start with a touch game of rugby. It is key that attack and defence is worked together where possible, like stated earlier. Initial conditions, which we can call task constraints, would be the size of the pitch, the numbers on each team and then what a “tackle” is and the rules of the game.

The players would work out how to score tries or stop tries being scored in that game. In simple terms, the affordances in this game are the spaces between defenders for the attackers to run at, the space behind the defence. The physical environment constraints are wind, rain and the surface. The Individual constraints are skill level of the attackers, speed, evasive skills of attackers and mental state of each player, that is, the mood they are in, motivational and fatigue levels.

As coaches, we need to manipulate this environment, changing the task constraints, individual constraints and environment constraints to challenge the players.


We can vary the time of game play to challenge players. For example, the attack has six minutes with the ball. We as coaches can manipulate the different constraints to make the defending team more dominant, so when the ball carrier gets touched, they go to the ground and present the ball. The next two attackers must go over the ball carrier, so there is, now, say seven attackers on their feet against 10 defenders.

The defenders could get direction from us on how to be more effective, or they can self-organise. To do this effectively, we nominate three defensive leaders to make the adjustments. You can give them guidance on what to look for in terms of their strengths. Perhaps they have some fast players or players who are very direct. How would the player defend against that, what would you do? If they are in the middle of the pitch or at the side, what would you do?

They are tasked to take control of what they do and then find out what happens next. You can then give them some feedback on what went well and what they think they might change. You can do that in the game, as it’s rolling, not stopping it during that six minutes.


We can then change various constraints of the game to allow for more affordances. Remember these are opportunities, not specifically looking for an action to take place. For instance, if you make the pitch bigger, you aren’t looking for the players to specifically spread out or use a certain type of defence. You are posing a question for them to answer in their way.

You can also develop the environment constraints, relating to socio-cultural development. When they do force an error in the attack, they might come up with a way of celebrating, and build their team cohesion.

Changing constraints can be used to destabilise the defence. Perhaps they were being successful with their current solutions. Take out defenders, change the leaders, give the attack three seconds to offload the ball, give defenders different coloured bibs which allow them to make different sorts of tackles. For example, a red-bibbed tackler can make a turnover if they make a touch. These are task constraints added in or could be Individual constraints if the coach chooses the defender in the red bib for example.

Further ideas could be that the defence has three phases, or unlimited phases after a turnover, so looking at the transition from defence into attack.

All these constraints offer affordances that are representative of the game. They destabilise leading to defenders having to self-organise, just as they might in the match on the weekend.


Either you or the team could identify scenarios from the game which are then put into training situations. For example, how do we defend from a lineout, against a team that kicks long, or where an attacking team start play from a ruck in the centre of the field in the defence’s half to simulate an attacking break.

Whatever the scenario, the players need to go back to their principles and see how they can enact them in that scenario.

The scenarios set are task constraints and could be that the defending team are 10 points up and the attacking team have three attacks to win. We could set the attacks up from a lineout, scrum, open play, kick restart, kick in open play so a defensive exit play.


Constraints influence the behaviour of the player. The word “constraint” suggests they prevent something from happening, but they can also lead to something else happening.

There are three main constraints which lead to a skill being performed:

Task constraints are factors that are closely related to the performance of the task and are the ones the coach and player can manipulate, for example, the rules of the game, the size of the pitch, the numbers on each team.

Environmental constraints are factors that can’t be manipulated immediately, but still impact on the players physically and socially – the pitch conditions or weather and social expectations like, for instance, wingers might want to avoid contact and props won’t!

Individual constraints relate to the players directly like their skills (physical and mental), speed and decision-making ability.

The coach and player, through co-design, aim to manipulate the constraints to help the players discover movement skills to reach their goal.

For example, the defender needs to make a tackle and the attacker to beat the defender to score a try.

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