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How much difference do external cues make?
When giving cues, we can categorize the type of cue into those that have an external focus and those that have an internal focus. External cues are generally used when the goal is to produce a better objective performance (e.g. a longer jump or a greater power output). But how much difference does the type of cue actually make? In this article, Chris Beardsley (@SandCResearch) reviews a study that helps provide the answer.
The study: Effects of varying attentional focus on health-related physical fitness performance, by Bredin, Dickson and Warburton, in Applied Physiology: Nutrition and Metabolism, 2013
What’s the background?
Coaching instructions can direct the focus of attention externally or internally. An external focus is one that directs the athlete’s attention away from their body and towards the effects of their movement on the environment. An internal focus directs the athlete’s attention to their own body movements. Previous research has found that an external focus of attention is optimal for improving the objective performance of the movement (i.e. greater jumping distance or height, greater power output, etc.) while an internal focus leads to reductions in objective performance but may lead to better form, as measured by differences in joint angles.
Marchant (2009) – the researchers found that an external attentional focus led to greater force and torque during isokinetic elbow flexion movements while simultaneously decreasing muscle activation as measured by EMG.
Porter (2010) – the researchers found that directing attention toward jumping as far past the starting line as possible had a much greater effect at increasing broad jump distance compared to focusing attention on extending the knees as fast as possible.
Wulf (2010) – the researchers found that an external focus led to increased jump height with simultaneously lower EMG activity compared to an internal focus of attention.
Wu (2012) – the researchers found that an external attentional focus let to increased broad jump distances despite not affecting peak force production compared to an internal attentional focus.
Makaruk (2012) – the researchers found that 9 weeks of plyometric training with an external focus led to greater standing long jump and countermovement jump (but not drop jump) performance compared to training with an internal focus.
Porter (2012) – the researchers found that an external focus far away from the body led to greater results than an internal focus or an external focus near the body in terms of standing long jump performance.
So in general, the main factor that is associated with external focus is an increase in performance. Also, there may be a tendency for reduced EMG activity at the same time. This is interesting, as it may be a mirror image of what happens with internal focus.
What did the researchers do?
The researchers wanted to compare the effects of internal and external attentional focus on performance in a health-related physical fitness appraisal. Specifically, they wanted to see whether the difference in focus would alter performance in parts of the musculoskeletal and aerobic components of the Canadian Physical Activity, Fitness and Lifestyle Approach (CPAFLA) test. The CPAFLA test is administered on more than 1 million Canadians each year by trained and certified health and fitness professionals.
The researchers therefore recruited 16 young but untrained adults (8 females and 8 males). The subjects performed certain specific parts of the CPAFLA test 3 times in a randomized cross-over design, with one performance using external cues, another using internal cues and a third using no cues. The aerobic part was the modified Canadian Aerobic Fitness Test and the musculoskeletal tests involved grip strength, push-ups, sit and reach, partial curl-ups, vertical jump, and a modified Biering–Sorenson (horizontal) back extension test.
The researchers found that external cues resulted in significantly better performances for all 7 measures of health-related physical fitness in comparison with both internal cues with no cues. Also no cues resulted in significantly better performance for 3 measures (grip strength, push-ups, and vertical jump) in comparison with internal cues. The following chart shows the difference in vertical jump performance between the three types of cue for both males and females:
The researchers found that external cues improved vertical jump performance by around 10 – 17% in untrained males and females in comparison with no cues. Additionally, the researchers found that external cues improved vertical jump performance in untrained males and females by around 15 – 22% in comparison with internal cues. While such large differences might not be expected in trained subjects or athletes, it is evident that external cues make a very marked difference on the objective performance of large, full-body, explosive movements such as vertical jumps.
What did the researchers conclude?
The researchers concluded that for sporting performance movements requiring the generation of force or power, performance can be enhanced significantly by externally-directed cues. So it appears that when instructed to focus attention outside of the body and toward the interaction with the environment, the neuromuscular system is coordinated to a greater degree compared to an internal focus inside of the body. With external cueing, the precise motor units are activated to the optimal degree at the optimal onset times in order to maximize performance, whereas with internal cueing, an unnecessary amount of motor units may be activated and force production may be altered in a way that negatively impacts performance.
What were the limitations?
The study was limited in a number of key respects:
- No biomechanical data was recorded to show whether the subjects changed the way in which they performed any of the movements when the different cues were used.
- The subjects were untrained and different results might be expected with trained subjects who were more accustomed to performing the movements.
- No resistance training exercises were performed. Therefore, it is difficult to assess whether a similar magnitude of performance enhancement might be expected with, say, a standard back squat as with the vertical jump.
What are the practical implications?
Large, powerful, full-body movements such as plyometrics and probably also resistance exercises can be significantly enhanced by appropriate, externally-directed cues.