Key Concepts: Go single early - the importance of unilateral work
1. Aim
To explain why, although unorthodox, utilising single limb (unilateral) exercise variations early in training and rehabilitation should be par for the course across all sports and physical activities.
2. Intended Audience
Coaches, S&C coaches, PTs, all rehabilitation professions, professional athletes, recreational athletes and any one with an enquiring mind.
3. Key Points
- Unilateral exercise does not have to mean increasing the load or intensity of a drill
- Far greater application to daily functional activities and sporting activities
- Greater engagement of trunk encouraging a proximal (close) to distal (far) patterning
- It does not mean there is no place for bilateral (both limbs) work
- It inherently helps to address imbalances, especially rotational imbalances which, in my experience, are nearly always involved in clients injuries and dysfunctions
Whether coaching a sport, fixing someones knee or training for your first marathon, the amount and timing of load you place on your body is a defining factor in achieving success. Too much load and you break yourself, too little load and you don't create the adequate stimulus to encourage adaptation and become too weak for your chosen activity. Again you break yourself. Traditionally therapy and training methods recommend performing bilateral drills first and that unilateral drills are a progression primarily due to increased load. This post discusses why this approach is incorrect and potentially injurious.
5. So how do we define load in training?
This is actually quite difficult. Load is a very broad term. Alot of the literature tends to look at it in terms of acute and chronic. Acute being the amount and intensity of training over the short term (so weekly or individual sessions), whilst chronic load takes a longer term view, normally over about 4 weeks. But for me this is too simplistic, especially when dealing with game related activities like football, rugby, hockey etc. The reason being is they require you to think, which increases cognitive load. Thinking tires you out. Running around kicking a football versus just running around, requires more brain input and so it is more tiring. Activities that require you to identify stimulus, decide and then act, also increase cognitive load. Then there is neural load, yes that's right, it is not just the the stress on your muscles and ligaments when performing an action, the nerves have to make it all happen and in doing so they can get tired too. Then we have to remember other factors like sleep (or the lack thereof) and general life stresses of relationships, finances and so on, all of which can affect the total load you experience at that point in time. For the purposes of this post we will simplify it to only mechanical load i.e. the physical forces placed on your body or produced by your body. But keep in mind these other stressors mentioned here as we unpack the issue further.
6. Bilateral or unilateral: which loads you more?
In short, neither. Both methods can be dialled up or dialled down by using different exercises and external aids. For example a 1RM (1 repetition max - the amount of weight you can lift for 1 rep) barbell back squat places far more load on an individual than a single leg squat using a suspension trainer like TRX.
Source: https://www.pinterest.com/pin/574983077397098252/
For me this is the crux of the issue. For a long time it has been doctrine to build someone through bilateral drills first, then progress in later stages of training to unilateral work. Certainly if you take someone with a limited training base and get them doing aggressive single legs bounds on a field you are asking for trouble! However, it is not because the drill is unilateral, it is because the load is just way too high for the individual. In 9 out of 10 cases where the load is too high, it is the supporting muscles that control the spine, pelvis and hips that have been found wanting. If these are not ready for the activity in hand, you have a problem.
7. Go single early
It is fair to say that unilateral drills are generally more challenging for the athlete but not because of the load. They are more challenging because they require far greater balance, proprioception (sense of where your body parts are in space), stability and control of rotation across multiple joints. These are normal factors in just about every action we carry out in sport and daily life for that matter. In fact, we very rarely work bilaterally, with force evenly distributed around our body.
Take something as basic as walking for example. 40% of the time you spend on one foot or the other. 60% of the gait cycle is classed as a stance phase i.e. the foot is in contact with the floor, but approximately 20% of this we are in double stance (both feet in contact with the floor). But even when we are in double stance phase our pelvis is rotated and shoulders counter rotated, not to mention the load on different parts of the body is highly variable as we are in motion.
Source: https://www.researchgate.net/figure/Phases-of-the-normal-gait-cycle_fig3_309362425
In running we get rid of the double stance phase. We are permanently on one leg (or the other). In grappling sports weight is continuously being transferred between limbs as they manoeuvre for advantage and then during a tussle the forces are asymmetric with balance, rotation, proprioception, flexion, extension and lateral flexion of different parts of the body all happening at once. So why on earth do we still build the majority of a strength and conditioning (S&C) programme around static, simple, bilateral lifts. The standard bilateral back squat does challenge the individual but not in the ways that best prepares them for activity outside the of the gym environment, which for the vast majority of us is why we are partaking in an S&C programme in the first place.
8. So there is no advantage to doing any bilateral work?
Bilateral work definitely has a place in a sound S&C programme. Bilateral drills are really good for getting large external loads on an individual to help create strength adaptations. This is important for activities that require large force outputs like contact, collision and combat sports. But we do not need to do these anywhere near as often as many would have you think. For example deadlifts, if performed in the 1-5 rep ranges, that are utilised to create strength adaptation, can take anywhere between 10-21 days to fully recover, at a cellular level (depending on which research you read). But a lot of programmes will add heavy deadlift on a weekly basis. Which is pretty stupid when you think that all your gains are made during the recovery and that to improve your strength you need to nearly fully recover between sessions to maximise output. This classic "less is more" ideology certainly helped me when I was big into my rugby. I was training really hard at university trying to push my deadlift PB. I had heavy deadlifts once or sometimes twice a week. I hit a pretty big plateau at which point the term was over and I returned home for the break with out access to a gym. So I did running and body weight exercises to tide me over. On return to the university 3 weeks later I smashed my PB by around 10kg. At the time I couldn't believe it. It seemed backwards and non-sensical. Only a few years after, having come across the research, did it finally make sense that I had just never given my body the time it required between sessions to properly recover and adapt.
A group which of course will benefit from large amounts of training bilateral drills, are those involved in lifting sports such as olympic lifting or power lifting. This is because the purpose of their training is to lift the most weight they can for 1 repetition. From a movement pattern perspective it makes sense to spend alot of their time reinforcing the neural pathways that enable them to get more efficient and stronger in bilateral movements because this is how they perform in competition.
On a side point, I believe the reason that most S&C programmes heavily utilise bilateral lifting, is because in the formative years of developing gym based strength programmes for athletes, coaches looked to the premiere strength disciplines like Olympic lifting and Power lifting to see what they did. I stress this is purely a theory, with no evidence other then my own experience but an interesting thought nothing the less. The theory being that strong is strong and if you can lift a shit ton of weight off the floor, YOU STRONG! It must be said there is some logic and evidence to support this theory. For example there is a clear link between vertical jump heights and sprint performance - and Olympic lifters have pretty good vertical jump heights. As of course they should. They spend their days basically doing resisted vertical jumps with loads often exceeding 2 times their body weight. But vertical jump and straight line sprints don't mean you're agile, which is an important part of all sports outside of lifting. I would be getting way off topic if I discuss here why I think that Olympic Lifting is sub-optimal in S&C programmes for developing power, because it isn't, despite what the journals say. But my main point here is that you are not looking to get stronger in the gym environment (unless you just enjoy show boating in the gym in which case crack on). You are not looking to get stronger at a specific lift (unless you are a competitive lifter, in which case crack on). You are looking to perform better at your chosen activity. This must therefore be the focus of all your activities.
Coming back to lifting sports, although it makes sense that the majority of their training is bilateral, they still get massive benefit from integrating SOME unilateral drills into their programme. This is because unilateral drills inherently help to address imbalances through the trunk and limbs. Especially rotational bias (the trunk and load bearing joints prefer to rotate one way, over the other, when compared left to right in the body) which most of us have to varying degrees. In those with larger amounts of rotation bias we often see injuries. The other more obvious bonus to unilateral work is that if you have one leg far waker then the other you are not accessing your full power when lifting - this is actually very common. Bilateral training often allows you to cover up the weakness of one limb, by by taking up the slack on the other. This is often seen with dramatic effect on pressing drills. If some one has only ever barbell bench pressed and you place them on dumbbell bench press, they suddenly find one arm lags behind, often to the great amusement of the bystanders. Time spent training that weaker side will decrease the risk of over use injury on the good side and improve over all performance. It's win win! The only thing you have to do is park your ego as you'll be lifting far lower weight then you're used to whilst your weaker side catches up. This is not rocket science and yet so often we neglect it, knowing full well that we are dramatically weaker on one side.
To summarise, bilateral work has a place in all S&C programmes but the amount of bilateral work should depend on what the individual is training for. Outside of body building and lifting sports, pretty much everyone should be focussing first and foremost on unilateral drills, with bilateral drills taking a secondary roll.
9. Recommendations
As a general rule, 80% of your programme should be centred around unilateral work and/or asymmetrical loads and stances, with 20% being standard symmetrical bilateral drills (i.e. back squat, deadlift). By asymmetrical stances I am referring to positions such as split stances (one leg forward, one leg back). Asymmetrical loads, however, refers to biasing the load to one limb or the other. For example performing a standard deadlift but with weight only on one end of the bar. Yes, the individual is in a bilateral symmetrical position but the asymmetric load means we create a lateral shift and force rotation, which asks more questions of the athlete, which is why I class it as a unilateral drill.
The bilateral work should take advantage of the inherent stability involved in such positions and get the load up. 1-5 reps, 5-10 sets, with large rests in between of around 3-5 mins. Big lifts, lots of load, lots of rest, large duration between sessions for full or near full recovery.
If we are talking about lifting sports, we use the inverse of this rule, 20% unilateral and 80% bilateral. The bilateral drills will make use of high load but also various other loads for power, volume etc as part of a lifting specific programme. Because of such a high percentage of bilateral drills, the unilateral work for lifters should be pure single limb activities such as single leg squats, single arm pressing drills and so on.
10. Summary
A big, bilateral lift, from a stable base, in the gym, does NOT equate to better performance on the field of play. It is more complicated then that. It simply means you have become good at that specific lift. By going unilateral early you get more bang for your buck, addressing muscular imbalances, improving proprioception, improving balance, decreasing injury risk, as well as improving strength, power or endurance depending on what you are training for; all of which improves your performance in your chosen activity. Remember your S&C programme is there to support you achieving your goal, it is not the goal itself. Most of the challenges posed by the majority of physical activity will require you to be really good at controlling unilateral loads, asymmetrical loads and working from asymmetrical stances. So train that way.
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