How do external cues work?
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Decades of research has demonstrated that the focus of attention used during a movement affects its immediate performance, and also affects the long-term improvements that occur in relation to that movement.
Early research in this area focused primarily on the performance of skilled movements, while later research has also included the performance of more strenuous physical tasks. Indeed, recent research has shown that adopting an external focus of attention (immediately) improves performance during skilled movements (including strenuous activity like strength training exercises), and also permits greater long-term improvements to occur in those movements.
What is attentional focus?
Attentional focus refers to what an individual is thinking about (directing their attention towards) during the performance of a movement. When attention is directed externally (towards an object outside of the body), then the focus of attention is said to be an external focus of attention. When attention is directed internally (towards a part of the body), then the focus of attention is an internal one. If no specific focus of attention is used, the state is often said to be a neutral one.
What does an external focus of attention achieve?
During strength training exercises and strength tests, an external focus of attention has sometimes been shown to increase the force that can be produced, even when maximal efforts are being used. An external focus of attention has also been shown to enhance the number of reps that can be done during a set performed to failure. What is more, an external focus of attention increases vertical jump height, horizontal jump distance, throwing distance, and sprint running speed.
For immediately improving strength training exercise performance or athletic performance, an external focus of attention is very effective!
While the majority of the research into the effects of an external focus of attention during physical movements has investigated the immediate effects of using such cues, a small amount of research has also assessed the long-term effects of using external cues during training. It seems that using an external focus of attention produces similar strength gains to an internal focus of attention, but smaller increases in muscle size. Since hypertrophy contributes to gains in maximum strength, this suggests that, for the same amount of hypertrophy, an external focus of attention causes greater strength gains, by means of neural mechanisms.
But what neural adaptations does using an external focus of attention enhance?
What neural adaptations does an external focus of attention enhance? – coordination
Early research into attentional focus identified that an external focus of attention increased the performance of skilled tasks by improving coordination (both immediately and long-term). It therefore seems likely that the same effect occurs during more strenuous physical tasks, like strength training exercises and athletic performances. Yet, this is difficult to assess, because there are few exercises and athletic performances in which coordination can be measured with any degree of objectivity.
Nevertheless, the standing long jump for distance presents a very useful opportunity for coordination to be assessed, because horizontal jumping distance is greatly affected by the angle of take-off, in addition to the impulse that is produced. Research has shown that using an external focus of attention improves this take-off angle by causing it be directed more horizontally, because most individuals employ a take-off angle that is directed too vertically. This observation provides evidence that an external focus of attention improves the coordination of a physical task by altering the movement pattern such that the task is performed more efficiently, and is therefore achieved more successfully. It also suggests that when elements of a physical task involve submaximal effort (such as the early reps of a strength training set performed to failure), then those elements might be performed more efficiently.
Additionally, if an external focus of attention works primarily by improving coordination (both immediately and long-term), then we would expect it to produce increases in athletic performance (which it does), increases in the number of reps in a strength training set (which it does), and even maximum strength (which it does), but without affecting muscle growth (which it doesn’t). Thus, the idea that an external focus of attention works primarily by improving coordination fits well with most other observations.
What neural adaptations does an external focus of attention enhance? – reduced antagonist coactivation
While an external focus of attention clearly enhances exercise performance by improving the coordination of the movement pattern, it also seems to work through an additional (albeit closely related) mechanism. Indeed, some recent research has shown that using an external focus of attention reduces the level of antagonist coactivation in an exercise.
During many movements, the antagonist muscle contracts at the same time as the agonist, albeit to a lesser degree. While this contributes to joint stability and improves control over the movement, it also reduces the external joint torque for a given level of agonist muscle force. For this reason, a reduction in antagonist coactivation improves strength and exercise performance. It seems likely that reductions in antagonist coactivation occur in response to an improvement in the ability to provide the necessary stability at the joint by activating synergist muscles, as well as by improving balance. Indeed, coactivation is often high when unstable exercises are first performed, and it reduces rapidly as these exercises are practiced.
Using an external focus of attention therefore seems to accelerate the processes of learning to use the synergist muscles or of improving balance in order that antagonist coactivation can be reduced safely. This adaptation has essentially the same effect as an improvement in the coordination of the movement pattern.
Indeed, while reducing antagonist coactivation increases strength and exercise performance, it does not affect the ability to increase muscle size. Reducing the level of antagonist coactivation simply increases the amount of external joint torque that occurs for any given level of agonist muscle force. It does not change the conditions that the muscle fibers within the agonist muscle experience, nor does it change the level of motor unit recruitment in the agonist muscle. Thus, while a heavier weight might be lifted for a larger number of reps once antagonist coactivation has reduced, the experience of the agonist muscle in the set will remain unaltered. Consequently, we would not expect any alteration in the level of antagonist coactivation as a result of using an external focus of attention to affect hypertrophy after training. Indeed, this again fits with the current research, which has found no obvious benefit of external focuses of attention for muscle growth.
What neural adaptations does an external focus of attention enhance? – increased motor unit recruitment
Although there are two very obvious neural mechanisms by which an external focus of attention can enhance exercise performance both immediately and also long-term, some researchers and commentators have suggested that an external focus of attention might also increase the level of agonist muscle activation, by means of an increase in motor unit recruitment.
Indeed, this could occur if the external focus of attention increased motivation, since motivation levels limit the maximum level of effort that can be tolerated, and the perception of effort limits the motor unit recruitment that can be achieved. Indeed, it seems logical that providing an external target might be motivating for an athlete.
However, there are two reasons why we must reject this hypothesis.
Firstly, most studies that have compared the levels of muscle activation in the agonist muscles when using an external focus of attention and when using either no focus of attention or an internal focus of attention have found that muscle activation is actually lower with an external focus of attention! While muscle activation is by no means a perfect representation of motor unit recruitment levels, it is still an indicator.
Secondly, when the ability to recruit high-threshold motor units is increased, this causes an improvement in the ability to achieve hypertrophy. Indeed, this is why a block of heavy strength training potentiates the muscle growth produced by a subsequent block of moderate load strength training. Using heavy loads causes greater improvements in the ability to recruit high-threshold motor units, which means that future blocks of training are able to train more muscle fibers in each working set. Since using an external focus of attention does not enhance hypertrophy, we must assume that it does not increase the ability to recruit high-threshold motor units, either acutely or over the long-term.
Why is it important to identify which neural adaptations are enhanced by external cues?
To identify the practical implications of using external focuses of attention, it is important that we know which neural adaptations are enhanced by external cues. Indeed, there are two key takeaways of the above analysis.
Firstly, as noted above, if external cues work by improving efficiency (by increasing coordination and by reducing antagonist coactivation), then they will not affect hypertrophy. Thus, they are of little use for bodybuilders.
Secondly, if external cues work by improving efficiency (by increasing coordination and by reducing antagonist coactivation) and do not increase motor unit recruitment, then although they are of great value to athletes during sporting movements (such as sprinting, jumping, and throwing), they are probably of little use during most strength training exercises. This is because increases in coordination and reductions in antagonist coactivation are very movement-specific, and stimulating these adaptations in one exercise does not lead to similar adaptations in another exercise that involves the same muscle group. In contrast, increases in motor unit recruitment are highly transferable between movement patterns that involve the same muscle group.
What is the takeaway?
It is likely that an external focus of attention improves strength training performance and athletic performance by means of an improvement in movement efficiency (by improvements in the coordination of the movement and due to a reduction in antagonist coactivation). Consequently, this adaptation is unlikely to transfer very far beyond the movement that was practiced. In this way, these adaptations differ quite markedly from an increase in motor unit recruitment levels, which transfers very extensively between movements that involve the same muscle.
In practice, an external focus of attention is therefore likely to be very valuable when an athlete is training with a movement that will be used in sport (such as the powerlifting exercises for powerlifters, and jumping, throwing, and sprinting for many team sports athletes). Yet, an external focus of attention is unlikely to have the same benefits if it is used during an exercise that does not use a movement pattern that is employed during sport (such as a Nordic curl). In such cases, it may be better to employ coaching cues that can increase motor unit recruitment by increasing the level of motivation that is present, which increases the level of effort that the athlete uses. Ultimately, therefore, while an external focus of attention has often been proposed as essential for athletes in all exercises, this is probably not the case. It would be more accurate to say that an external focus of attention is essential for certain movements for certain athletes.
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