Last week, our head of rugby in school invested in some alternate rugby balls, to aid player development. Within the set, there was one heavy ball, one light ball, one “no grip” ball, and one variably weighted ball (to be pumped up with water rather than air). While it might seem odd to train with something that is not used during the competitive environment (i.e. not representative), I believe it can add value, at appropriate times and in appropriate doses. Using alternate rugby balls within rugby training (other alternatives could be footballs, AFL balls, volleyballs, tennis balls, basketballs) could be considered a form of differential learning (DL). DL involves athletes practicing a particular skill in a variety of forms. Every repetition they do is different - the process is always changing, but the outcome remains the same. Athletes will find a movement solution that works best for them, given their own body, and the environmental conditions.
I briefly touched on differential learning during my post on variability. I have mentioned previously, but the whole concept of variability was the most challenging aspect for me to understand and articulate when I started my journey in skill acquisition. I very much had an opinion of progress from remedial to difficult, which is not really the case anymore (see below for clarification), and an athlete needs to master a skill in one context before changing the context. This is obviously quite a complex issue. When dealing with an athlete, I would place them in one of two buckets:
Learning to Coordinate: An athlete learning to coordinate is either a complete novice (thinking about an U6 rugby player, or even an adult player who is looking to change their technique). These athletes exhibit a wide range of movement variability combined outcome variability. Remedial, isolated, decontextualised (pick your term) training is of use for athletes in this bucket.
Learning to Adapt: An athlete who is learning to adapt is beyond the early stages of learning. They exhibit some movement variability, but their outcome variability is more stable. These athletes need variability to ensure they are put in situations where they need to adapt the movement behaviour but still achieve the same outcome.
It is important, therefore, to consider the initial skill level of your athletes (among other things), prior to deciding on a training intervention. DL is a training intervention that is useful only in the learning to adapt phase, in my view. For athletes in the learning to coordinate phase, DL will cause too much noise and potentially lead to a challenge point that far exceeds the athletes’ capabilities, potentially leading to negative consequences, like loss of confidence or drop out (more specifically for youth athletes).
DL can be used to increase variability, which aims to promote adaptability. Adaptability, in essence, is skill. Skill is the ability to adapt