By: Keats Sniderman CSCS, LMT, NMT
Take a venture through the popular training magazines and journals these days and you’ll read about the many virtues of single-leg exercises. Movements like single-leg squats and deadlifts, step-ups, and many varieties of lunges are becoming the mainstream form of training in both private training facilities as well as commercial gyms. Even more popular is to perform these movements on “unstable surfaces” such as squishy disks, upside down ½ Swiss-balls (Bosu Balls), and wobble (balance) boards for example. In fact, these single-limb exercises have become so popular, that many strength coaches, physical therapists, and personal trainers are starting to abandon traditional bilateral movements such as squats and deadlifts. These traditional movements are even being touted as “nonfunctional” and even dangerous by some. I think we need a little reality check here. Therefore, this article will discuss and highlight many of the claims for and against single-leg and bilateral movements respectively.
The Current Arguments/ Some Rational Responses
Listed below are some of the most common arguments given on why people (especially athletes) should focus mostly on single-leg exercises. Following the arguments are some rational responses:
1) Since 60% (approximately) of the walking cycle is spent on one leg (aka “Stance Phase”), most of our lower-body strength exercises should be performed on one leg.
Response: While it’s true that a large percentage of the gait cycle is spent on one leg during the stance phase, this does not prove single leg exercises’ superiority over bilateral movements. This 60% is also based on research during walking. In what sporting situations is walking the goal? The same research used in the current argument also shows that this stance phase decreases to 40% during running. During sprinting, the stance phase gets even shorter. The bottom line: in most sporting situations in which running speed is important, your goal is to spend less and less time on one leg, and more time in the air, also known as a “float” or “flight” phase. In that case, I’m going to argue that skydiving is the most sport-specific activity of all!
Additionally, what many people who use this argument fail to realize is that during the gait cycle you are using stored elastic energy which helps to generate motion and maintain balance (keeping your Center of Gravity within the Base of Support). This is similar to the gyroscopic effect that keeps a bicycle in motion. Also, the momentum generated during gait and the use of stored elastic energy causes the hip muscles to activate in a much different manner than when performing single leg strength exercises.
From the scientific field of human motor control, we know that there are two primary types of movements: ballistic and co-contraction. With ballistic movements, there is an initial burst of muscular activity followed by period of relaxation during which limb motion continues as a result of limb momentum and stored elastic energy. In contrast, co-contraction occurs when there is a simultaneous contraction of both the “agonistic” and “antagonistic” muscles. Co-contraction activities (like many strength exercises) often use less elastic energy and are thus very different from a body in motion. This is why it’s actually more fatiguing on the muscles of your legs, pelvic girdle, and spine to walk slowly than at a slightly faster, more natural pace. This brings to mind the many ventures of window shopping I used to engage in with my mom and sister as a youth; I would ALWAYS feel so tired and drained very quickly when having to stroll around the mall at this slower pace!
To recap, many of the popular single leg (including bilateral movements!) exercises today are vastly different in the motor control characteristics when compared to the gait cycle (whether walking, running or sprinting) and other sports specific actions. This does not mean that single leg exercises are not valuable, it just serves as a reminder that nothing is as specific as performing the exact sporting task itself.
*Note- if you want a good reference on-line for the human gait cycle check out:
2) Single leg exercises are better than bilateral movements for training balance and are thus more “sports-specific.”
Response: It’s hard to deny the increased demand on balance during single leg exercises. However, coming to the conclusion that these exercises will improve balance in sporting situations better than bilateral movements is far fetched. One thing that seems to be forgotten is that balance is very specific to the situation in which it is needed. What this means is that balance in one situation doesn’t automatically transfer to all other situations. Science has shown us that there is no such thing as “general balance.” If there was such a thing, you would expect a person with great balance on skis to have great balance on a surf board, a skateboard, and a tight tope. Someone who appears to have good all around balance probably just has good body coordination, reactive ability and a highly conditioned nervous system which includes a keen ability to use his/her “righting reflexes.” These are the same reflexes that allow a cat to almost always land on its feet at the end of a fall. As a side note, athletes would probably get more out of practicing some of the martial arts (especially Judo, Aikido and others), some basic gymnastics tumbling moves, and some change of direction sprint and agility work.
With regards to specificity, the actual goal of “sport-specific” resistance training should be to increase force absorption (eccentric and isometric strength) and force generation (concentric strength) in similar ranges of motion and positions that are encountered in sport. Exercises like Front Squats and Snatch Grip Deadlifts fit the bill nicely here as they strengthen the hip and thigh musculature over a full range of motion. These movements also allow enough load to be used to stimulate muscle strength and hypertrophy by effectively activating the endocrine (hormonal) system.
But then, it’s up to specific practice of one’s sport or activity to improve the actual “skill” needed. People need to realize that getting stronger through resistance training only enhances your “potential” to become a better athlete; you still have to perform your sport however!
3) Single leg exercises are safer on the spine than bilateral movements due to lesser loads
Response: While single leg exercises almost always involve less overall load to the spine, they can be significantly more stressful to the hips, knees and ankles. With exercises like lunges and single-leg squats (both excellent exercises) for example, very large loads can be transmitted to the hip, knee and ankle of the working leg. Many of the people performing these exercises might not be qualified to do them and most likely need a period of training with bilateral movements such as conventional squats and deadlifts to strengthen their legs and trunk in a safer and more progressive way. Some people are far too weak to even entertain doing some of the lunge, step-up and single-leg squat (& deadlift) variations you see being performed out there; yet these are exactly the exercises being prescribed by many personal trainers and even some rehab specialists specializing in so-called “functional training.”
I know that plain old bilateral squats (even with bodyweight to begin with) and deadlift variations are not that exciting to some, but it just might be what most people need for quite some long time. Remember, just because something appears challenging or is difficult to perform (like a single leg squat), doesn’t mean it’s safe or effective for everyone. Conversely, just because an exercise looks boring or easy (like a squat variation for example) doesn’t mean it’s not effective. Trainers and coaches need to design personalized exercise programs based on what their clients/athletes actually need, not on what they FEEL like giving them at the moment or what’s cool or in vogue in the latest fitness magazines.
4) Single leg exercises are superior to bilateral exercises for recruiting key stabilizing muscles like the Vastus Medialis (VMO), Gluteus Medius, and other hip stabilizers (i.e. hip rotators).
Response: There is no doubt that single leg exercises recruit several of the hip, knee, and ankle stabilizing muscles. All one has to do is stand on one leg and feel all the muscles that recruit in your entire body. This massive recruitment of muscles you feel is a good thing as your body does not want to fall! However, just because higher levels of muscle recruitment may occur during some single leg exercises does not mean they are more effective than bilateral movements. Since loading potential is much higher with bilateral movements, there is also more potential for hypertrophy and strength than with single leg movements. Bilateral movements allow for better dissipation of force/stress through the body which helps to avoid over-stressing any one area. In contrast, the more you isolate and add load to a given limb, the more joint stress that occurs; so this increased level of recruitment comes with a price since now all the stress is focused one limb’s joints, muscles, tendons, and ligaments. This may overload a vulnerable area.
I have determined on myself and countless others, that too much single leg work can absolutely toast the working leg’s hip abductor muscles (glute med, minimis, TFL) and leave them sore and riddled with trigger points and ischemia (lack of blood). With regards to ischemia, tissues that are ischemic are generally tender to the touch and the hip abductors are notorious for being ischemic. Even the contralateral lower back (primarily the quadratus lumborum muscle) can get strained and over-worked from excessive single-leg work. This occurs when the working leg’s hip-abductors fatigue causing the opposite side’s low-back muscle to kick in to keep the pelvis from dropping.
This article is starting to sound a little negative regarding single leg movements but please don’t get me wrong here, I STILL USE them regularly. For instance, if someone is performing a good deal of bilateral strength movements for their hips and thighs, I might add anywhere from 1-3 sets (usually 2) of Bulgarian split squats or single leg deadlifts for example, after the bilateral movements depending on the phase and goal of training. It all depends on what the goal is! And if I need to drop some exercises from the training plan on any given day, it will probably be the single leg exercises as they just aren’t the priority. Besides, many athletes are doing what amounts to a lot of single-leg training in their respective sports via running and change of direction movements.
The Reality of The Situation
In reality, I believe that many trainers and coaches are really just bored and thus get sucked into giving their athletes/clients exercises which are difficult and maybe popular (at the moment) without thoroughly thinking through the exercises and qualifying them for their respective clients. I’ve also been guilty of this in the past, but always find myself returning to the many variations of squatting and deadlifting because when taught properly, they flat out work and give you the most bang-for-your-buck with regards to training efficiency. It also apparent that many trainers and coaches don’t know how to teach bilateral movements properly and thus choose not to use them. Too bad. The following list shows the many varieties of bilateral movement that are available to the fitness enthusiast, strength and conditioning professional or rehabilitation specialist:
Snatch (full lift)
Clean (full lift)
Snatch Grip Deadlift
Deadlift off Platform
Hybrid Variations (neither a Squat nor a Deadlift)
Hack Squat (aka ‘Behind the Back” Deadlift)
Trap Bar Deadlift (fairly Quad-dominant)
DB/KB Squat (similar to Trap Bar Deadlift)
Keep in mind that all these movements can be performed with a variety of mediums (i.e. barbells, dumbbells, kettlebells, sandbags, odd implements and many more). The range of motion can also be limited or extended in any of these bilateral movements depending on the desired goal. The speed of movement is also easy to modify in these movements and can even be augmented by using accommodating resistance techniques (chains, bands, weight releasers, etc.). Those coaches and trainees that are familiar with accommodating resistance techniques know that they are much more feasible with bilateral movements than with single leg movements. There is a time and a place for occasional use of these techniques with single-leg movements however.
It should be mentioned at this point that single leg exercises are still a very valuable addition to any conditioning program and should be part of the toolbox of most coaches, trainers, and rehabilitation specialists. However, they should be thought of more as “assistance” exercises or side-dishes, rather the “main entrée” if you know what I mean. Maximal strength techniques are not that safe when you’re on one leg! However, there may be cases (as there always are) where someone would be better off doing some barbell or dumbbell lunges or step-ups for example, rather than loading a sore or tired back with heavy squats. It just really depends on the situation and the individual. The following list includes several variations of single leg exercises that are used quite frequently:
Stationary Lunge (i.e. Split-Squat, Static lunge)
Dynamic Lunge (single step and then return; either forward or backward
Bulgarian Split-Squat (rear foot elevated on box, bench, or in strap of TRX, etc.)
Single Leg Squat Variations
Single Leg Squat to Bench
Single Leg Squat off Step
Full Single Leg Squat (i.e. Ass-to-grass Pistol)- reserved for the mutants of the world!
Single Leg Deadlift Variations
Single Leg Deadlift (bent-knee, aka Single Leg RDL)
Single Leg Deadlift (nearly straight knee)
Single Leg Good-Morning
Lateral Step-ups (i.e. Petersen Step-ups, VMO Step-ups)
Regular Step-ups (of varying height)
A Word About Progression
As discussed earlier in this article, one thing that really bothers me is the lack of trainers and coaches qualifying their clients for specific exercises. As an example, I’ve seen countless trainers in gyms making overweight and deconditioned individuals perform exercises like walking lunges, single leg squats on a squishy disk and single leg deadlifts when these people probably couldn’t even perform a hands-free bodyweight squat without trouble. Yes, maybe the bodyweight squat is kind of boring and not as “cool” looking as the wobble board lunge, but if you’re client can’t even perform a bodyweight squat then what the heck are they doing standing on one leg bouncing on a Bosu Ball?
I have a better idea: let’s actually do what’s best for the trainee/client right now. Maybe later, after a good foundation of basic strength is built with exercises like squats and deadlifts, can the thought of single leg movements like lunges be entertained. And when you do start those lunges, how about beginning with a split-squat (aka “stationary lunge) before having people lunge around the gym with knees flailing like a new-born colt!
Another thought would be to first just teach your client to stand on one leg and balance without excessive swaying of the spine or pelvis (i.e. Trendelenberg sign). This will strongly recruit the ipsilateral hip abductors (i.e. Glute medius, minimus, and TFL) without the unnecessary stress of performing a single leg squat, deadlift or even a lunge. Once a proper single leg stance can be performed, a mini single leg squat can be performed as a great test of trunk, pelvic, knee, and even foot and ankle stability. These exercises can be also be used with great success as “activation exercises” prior to sport or resistance training sessions to facilitate hip, knee, and ankle stabilizer function. Watch for excessive trunk movement, pelvic instability, internal rotation and inward buckling of the femur and knee (varus stress), and pronation of the foot and ankle complex. Most people will demonstrate at least some of these compensations.
From here, multi-directional single-leg hops can be safely performed as an introductory force absorption and plyometric drill. To add difficulty, eyes can be closed or a blindfold can be worn. This dramatically increases the demand on the somatosensory (proprioceptive) system!
The Bottom Line
To conclude, I hope this article has been an informative and possible eye-opening foray into the highly disputed world of exercise prescription and the concept of sport-specificity. With a little common sense and some logical thinking, single leg exercises can be safely worked into a resistance training program, but not at the expense of the more productive bilateral movements that should be the cornerstone of any good conditioning program!
TAKU’s Note – About The Author:
Keats Snideman is a Certified Strength & Conditioning Specialist (CSCS) and a licensed massage therapist specializing in Neuromuscular Therapy (NMT). He is the owner of Reality-Based Fitness LLC, a performance training and massage center located in Tempe, AZ. He specializes in the enhancement of athletic-style fitness and has a proven track record for getting his clients results having coached and provided treatment to a variety of clients (athletic and non-athletic alike). Some of the clients Keats has worked with include athletes from the NFL, NBA, MLBA, USA Track & Field as well as athletes from both the collegiate and high school levels. For recreation and fun, Keats also competes as a competitive sub-masters sprinter (100 & 200m dashes). He may be reached at email@example.com or through his website at www.realitybasedfitness.com
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