Written by Peter Joffe
Introduction.
There is no doubt that the ability to change of direction (COD) is an important part of successful sports games’ performance. It is a necessary quality in the “contact” games (e.g., football, rugby, etc.), where this ability is crucial for not being intercepted by the opposition’s players while attacking and effective playing in defence. In “non-contact” games such as tennis, COD skill helps to win “difficult balls,” which demand multiple running from one side of the court to another.
It seems impossible to find coaches who don’t recognise this importance and do not include change of direction exercises into their Strength and Conditioning training programmes. However, there are some problems in COD training, which should be considered.
First of all, it is important to understand that change of direction in real game situations (agility) includes cognitive and physical components. The former includes anticipation and visual reaction, while the latter involves different kinds of strength and motor control. Sometimes, an athlete can compensate for a disadvantage in one component with an advantage in another. For example, an older defender can be better in 1×1 situations than a younger one, even though his physical abilities are already declining, thanks to an advantage in the cognitive components.
While both components can be trained together, it would be better to understand their relative contribution to the particular player’s performance to make training intervention more precise. Cognitive training for Sport deserves a separate discussion, and I hope to return to this exciting topic soon. Here I am going to discuss only the physical components of COD.
Game-related COD, straight acceleration and COD tests: Are the same qualities needed?
If we try to express COD physics in two simple words, they would be deceleration and acceleration.
To change the direction of his/her running, a player needs to slow down the original direction speed and then accelerate in a new one. Sometimes, a player completely halts his/her movement before accelerating in a new direction. According to Newton’s law, a force must be applied to either decelerate or accelerate. Therefore, the stronger the athlete is, the better he/she has to be in COD, right?
It turns out that this is not so simple, as we see when we begin to train or test COD qualities in real life.
Firstly, many of the current research studies failed to demonstrate a strong correlation between the ability to accelerate straight, and the ability to change direction (Little & Williams, 2005), though formally, both exercises demand the same quality— strength. It seems that the more turns an athlete perform at a given time, the lower the correlation is (Young, McDowell, & Scarlett, 2001).
Secondly, specific strength exercises that are believed to be useful for straight acceleration (e.g., loaded squat) probably are not helpful for COD (Brughelli, Cronin, Levin, & Chaouachi, 2008).
Thirdly, different tests that aim to measure COD abilities have been found to have problems with validity. Validity means that tests have to reflect real game performance. However, it is difficult to evaluate a player’s COD in the real game objectively (although the coach definitely has a subjective opinion about it).
There are some attempts to prove validity indirectly, comparing performance in tests with player’s level. The logic behind this strategy is that if higher-ranked players perform better, it would be a demonstration of the test’s validity. Green et al. tested this idea with junior rugby players (Green, Blake, & Caulfield, 2011), while Hachana performed a similar study with U-14 footballers (Hachana et al., 2014).
Although both authors claimed that they achieved validity with their new and moderated traditional tests, I am taking their result with some caution, at least, because of my scepticism about junior’s rankings. It would be much more interesting to compare COD tests between, for example, English Premier League and Championship players. Besides, COD tests often don’t correlate with each other therefore are determined by different qualities. (Chaouachi et al., 2012). Actually, it means that COD tests are too specific and often reflect performance in the test itself. Therefore, they are useless for the evaluation of abilities within a real game.
In other words, we have the situation when the straight acceleration is not related to standard COD (tests) and the real game’s agility, and the COD tests are not related to each other. For excellent reviews of this material, see (Sheppard & Young, 2006) and (Brughelli, et al., 2008).
Perhaps some other qualities allow athletes to perform COD better in real game situations. Besides, agility is a complex skill that depends on so many factors and initial conditions that it is challenging to test it in a controlled way.
Strength training for game-related COD.
Despite this complexity, strength and conditioning professionals still need to find workouts in addition to routine strength exercises that could help improve COD within a real game.
Let’s look at what is different about the game agility compared to straight sprints and COD tests?
First of all, one key difference is deceleration. It isn’t present in straight running (I am not taking into account vertical displacement). Although deceleration is presented in COD tests, it is completely different compare to games.
Another difference is the starting body position. It is fairly standard (and optimal) in the straight acceleration and COD tests. Nevertheless, this position is highly variable in real game situations. An athlete may find him/herself off-balance after decelerating before having to accelerate to the new direction (see pictures 1, 2 and 3).
Qualities which may contribute to better COD performance:
1. Developing the eccentric strength of the thigh muscles. That allows decelerating more rapidly and safely.
Support for that provides the studies comparing males and females (Brown, Brughelli, & Hume, 2014). Knee biomechanics during COD was found to be different between these groups, both in pre-planned and unplanned conditions. Also, the amplitude of knee rotations is greater for women. That can be explained by the differences in strength and Q angle (hip – shin angle is greater in women). Having weaker leg muscles may also be one reason why female athletes are generally more predisposed to knee injuries than men (Griffin et al., 2000).
2. The ability to apply force horizontally and laterally rather than vertically.
3. Being able to apply force with a single leg, rather than with both.
4. Exerting reactive force.
This is the ability to produce more force in a shorter extension-contraction period (e.g. bouncing higher back after landing). As a result, this can transfer to having a quicker COD (Young, James, & Montgomery, 2002).
5. Optimising core muscle strength and coordination.
That is needed for sudden deceleration and starting from the inconvenient position.
6. Certain morphological characteristics may play an important role.
Though players with lesser muscle mass, are at a disadvantage in maximal strength compared to more muscular and heavy athletes, they may need less force for acceleration and deceleration due to their overall lower body mass (and, if we think back to Newton, lower inertia to overcome).
Despite losing in stride length, the shorter player is also more agile in the turns due to the lower centre of mass. These advantages in COD for short and light-weight players may be especially noticeable within a “multi-turns” situation, where there are many turns in a short time. Such advantages can disappear, however, when fewer turns and longer runs are needed instead. Often, a trade-off exists between power and agility.
It probably wouldn’t be correct to say that mentioned above qualities are needed exclusively for COD running. For example, in their recent excellent work, G. Rabita et al. showed that the absolute value of Ground Reaction Force is not what distinguishes between elite and sub-elite sprinters. Instead, the horizontal component is higher for the elite group, which allows them to not “waste” force on vertical displacement (Rabita et al., 2015). Reactive force, without a doubt, is a necessary quality for straight sprints as well.
What is probably worth considering is the specificity of training these qualities, which should help to transfer improvements in particular quality to the agility gains in a real game situation. For example, jumps on one leg can be performed not only vertically or straight forward, which is useful for sprints, but also sideways, backward, with turns (for example, in tag games on one leg).
Playing different variations of the “tag” games on the slope surface allows facilitating braking abilities (downhill), as well as acceleration (uphill). Different starting positions may be used for sprints. There are ample possibilities for the coach’s creativity. Should we give up the “traditional” strength exercise? Definitely not. “Basic” strength must first be built, before implementing an intensive, COD related strength programme.
For instance, ability to apply strength with one leg is important for COD, but coaching experience says that dual leg exercises should be used before for the adaptation. The same is true for plyometric workouts. Some authors and coaches recommend achieving at least 1.5 bodyweight in the loaded squat before the athlete starts an intense jumping programme (Kutz, M.R. 2003). So really, it is not a question about the necessity of “traditional” strength for players; rather, it is a problem of when – and to what extent – it should be supplemented with a specific, game-related COD strength programme.
Pre-planned and Unplanned COD.
The last (but not the least) problem that I’d like to discuss further is the difference between pre-planned and unplanned COD. Though most of the coaches include special COD exercises and the tests in their training sessions, however, most of these exercises include some objects (poles and cones) as the reference points for changing direction. Therefore, in these conditions, the turns are pre-planned.
As a result, this can cause significant bias for training game-related COD. It isn’t only because the visual motor reaction is not present (turning point is known in advance, so there is no reason to react). Coaches can justify such an absence because they’re only aiming for the “physical” component of COD and are not going to improve a reaction. However, even the physical component is different when comparing pre-planned turns with unplanned ones.
So what are these differences? Let’s take, for example, downhill skiers. They can tell you that to achieve optimal results during the slalom, he/she needs to adjust body position, trajectory, and speed before the turning point and make a turn as smooth as possible.
The same would be right for athletes when they performing pre-planned COD during exercises or tests. When approaching the turning point, they show patterns of the pre-activation of the selected muscles (Besier, Lloyd, & Ackland, 2003), prior slowdown of their speed in sharp turns, and smoothing trajectory in COD with the lesser angles. They have time to lower their centre of mass in advance, thus making deceleration and the first phase of acceleration to the new direction more effective (see picture 1).
Unfortunately, players don’t have the same opportunities in a real game.
During the match, the player does not know when – or if – COD will happen. Even if this is known as, for example, in tennis, it’s not always possible “to prepare” the turn, because a full effort to the initial direction is needed. Therefore, when COD demand appears, the athlete’s body position, muscle activation, and centre of mass’s height may be optimal for the current movement but not optimal for the changes (pictures 1; 2 and 3).
Picture 1: Pre-planed and prepared turn during COD test.
Though it is still around 1.8 meters to the turning point, the athlete starts to prepare turn. Note his trunk and arm positions. They have influenced (decreased) his linear speed, however.
Picture 2: Pre-planed, but unprepared turn.
Though the turning point is near, Federer cannot prepare turn, because he has to run at full speed and even lean forward to reach the ball. As a consequence, his starting position for new acceleration is not optimal. Compare with the previous picture.
Picture 3: Unplanned and unprepared turn.
Nani (white shirt) was deceived by Messi, and he is now trying to catch his opponent. He is usually a very agile player; however, his body position looks clumsy. You can see difference between Nani’s body position and the body position of an athlete performing a COD test. His legs are parallel to each other, feet are directed in the “original” direction, though his head and eyes follow Messi. Nani’s centre of mass is outside bearing area (behind), so his position is unbalanced.
In the game, the time available to make the necessary adjustments is strictly limited. Therefore, other patterns of muscle activity are needed to perform turns with the maximum possible efficiency. Producing a greater eccentric contraction force with the thigh muscles, increasing the load on the knee joint (Besier, et al., 2003), (Brown, et al., 2014), and exerting different activity mode of the core muscles are among those altered patterns which are met in unplanned COD.
Differences between planned and unplanned COD are, in my opinion, the reason why it is difficult, if possible at all, to test agility skills for the sports games. Tests should be standardised and be the same for all players. Therefore, it would be difficult to achieve uncertainty. Nevertheless, when the movements are predictable, they don’t reflect a game’s actions.
Some authors tried to do so by including the “reactive” component into COD test. Veale had evaluated this by adding a two-choice visual reaction on light with the Australian rules footballers (Veale, Pearce, & Carlson, 2010).
Farrow et al. tried to implement a more ecologically valid design, with the netball players using pre-recorded video of the opponent’s movement as the stimuli for unplanned COD (Farrow, Young, & Bruce, 2005).
Both studies claimed to achieve validity. However, two-dimensional screen images and light flash can unlikely be a full-value substitution for a real opponent. Both designs are, in my opinion, overcomplicated and impractical.
To summarise the above, it would be right to say that unplanned or unprepared turns take a considerable part of all game’s related movements. They are significantly different from pre-planned actions. These turns demand specific abilities, and therefore, specific training. Though sometimes, it may be possible to achieve validity in reactive COD tests for some sports, it is not the same for most other sport games. Currently, in my opinion, games’ related agility remains a widely untestable ability.
Stimulus for the training unplanned COD.
So, what stimulus for COD training should be presented instead of cones?
There are more natural methods: usages of the game-related objects and their movements. These might be a ball for tennis, or an opponent in the case of the contact games. Their unpredictability in timing and direction of movements can make COD exercises really game related. Such training develops the cognitive components of COD, simultaneously with the physical ones.
The game itself is the most natural method for developing COD skills. Games can be used in different specific drills, including exercises, whose aim is developing a particular muscle group or function (e.g., eccentric quadriceps contraction, core muscles stabilisation function).
Games with a partner sometimes don’t look so “nice” as the exercises with the cones and poles, so it’s why many coaches consider them as a childish. However, we have to remember that training should reflect and emphasise game patterns and not simply be “training for the sake of training” because, at the end of the day, we are not playing against cones.
Conclusion.
1. Game-related COD is the different quality, which needs specific training.
2. Unplanned and game-related conditions should be used mainly for COD exercises.
3. Eccentric strength of the leg muscles, core muscles strength, and motor coordination are of great importance.
4. Strength exercises, where force is applied horizontally and laterally (e.g. lateral and back-forth jumps), and with the one leg should receive significant time in training.
5. Training should reflect the different starting positions and the dynamic situations.
6. Strength programmes for the prevention of injuries should take into consideration the movement’s patterns of the unplanned COD.
References.
Besier, T. F., Lloyd, D. G., & Ackland, T. R. (2003). Muscle activation strategies at the knee during running and cutting maneuvers. Med Sci Sports Exerc, 35(1), 119-127.
Brown, S. R., Brughelli, M., & Hume, P. A. (2014). Knee mechanics during planned and unplanned sidestepping: a systematic review and meta-analysis. Sports Med, 44(11), 1573-1588.
Brughelli, M., Cronin, J., Levin, G., & Chaouachi, A. (2008). Understanding change of direction ability in sport: a review of resistance training studies. Sports Med, 38(12), 1045-1063.
Chaouachi, A., Manzi, V., Chaalali, A., Wong del, P., Chamari, K., & Castagna, C. (2012). Determinants analysis of change-of-direction ability in elite soccer players. J Strength Cond Res, 26(10), 2667-2676.
Farrow, D., Young, W., & Bruce, L. (2005). The development of a test of reactive agility for netball: a new methodology. J Sci Med Sport, 8(1), 52-60.
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Hachana, Y., Chaab?ne, H., Ben Rajeb, G., Khlifa, R., Aouadi, R., Chamari, K., & Gabbett, T. J. (2014). Validity and Reliability of New Agility Test among Elite and Subelite under 14-Soccer Players. PLoS One, 9(4), e95773. doi: 10.1371/journal.pone.0095773
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Rabita, G., Dorel, S., Slawinski, J., Saez-de-Villarreal, E., Couturier, A., Samozino, P., & Morin, J. B. (2015). Sprint mechanics in world-class athletes: a new insight into the limits of human locomotion. Scand J Med Sci Sports, 31(10), 12389.
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Young, W. B., McDowell, M. H., & Scarlett, B. J. (2001). Specificity of sprint and agility training methods. J Strength Cond Res, 15(3), 315-319.