Unilateral Training

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Let’s start with getting the basics out of the way. First, the majority of sport are performed on one leg. Running, stopping, cutting and jumping primarily occur with one legs’ force production. Second, single leg training is an accessory exercise to program design, and therefore not the end all, be all of exercise modalities. Lastly, it is important to incorporate a well-balanced program before introducing single leg training and to progress your client safely and slowly.

Now that we have gotten the basics out of the way, who does single training and why is it important? Well, unilateral leg exercises are for anybody. An elderly client could perform single leg training to improve balance or to strengthen their legs to prevent injury. An athlete could perform single leg training to strengthen the co-contraction in their lower extremities that occurs when making a performance based movement, or even use single leg training to improve their vertical jump. Lastly, a client looking to improve their health could perform single leg training to prevent staleness in their programming or to help with or to improve a bilateral deficiency. The benefits of single leg training are endless, but the application is where trainers can share their knowledge.

As a trainer, the program you design should first guide your client through appropriate two-legged exercises to build neuromuscular coordination and a base of strength. This will ensure that your client has been appropriately progressed. Once the client has shown improved movement patterns, incorporating single leg training can help improve performance in daily life or on the field of sport.

What and Why Unilateral Training

In most sports, single-leg movements are an integral part of an athlete’s success. According to Santana (2001), “one easily realizes that much of the time, force production is generated by a single leg, even in situations in which both feet are on the ground, the weight distribution will often be unilaterally biased and will not line up the articulations perfectly” (pp.35). With respect to the specificity of training, it wouldn’t make sense for an endurance runner to solely strength train their legs with two feet on the ground, if the majority of their sport is performed on one leg. Santana (2001) stated “because of the lighter loads and the more functional positions used in this unilateral training approach, single-leg training could be instrumental in prolonging athletic careers while enhancing performance”.

With single-leg training, specifically plyometric training, an athlete can increase the cross-over of their training and potentially reduce injury. Baechle and Earle (2008) describe impulse as force multiplied by time, and power as force multiplied by velocity. In each of these, the common factor is force, which is “the product of mass and acceleration”. If an athlete can increase their ability to produce more force through single-leg plyometric exercises, impulse and power will improve, which according to Baechle and Earle will improve an athlete’s explosive capability. Another great point by Santana (2001) was how athletes must be able to control different parts of their body while producing forces on a “single leg, concentrically, isometrically, and especially eccentric”.

In relation to endurance athletes, Ebben (2001) believes that through improved strength, muscular power and core stability, cross-country athletes can improve running economy. He stated that a mixture of Olympic lifts incorporating maximal output and plyometric training is ideal. Santana (2001) points out that, “sprinting is a unilateral and mainly a horizontal movement… only one leg is loading the muscles to propel the body’s mass forward, while the other leg is in the swing phase preparing for ground contact” (p.66). When we look at explosive movements in the field of sport, many Olympic lifts or powerlifts can simulate those movements/musculature. For example, in the clean, the body moves a load from a low point to a high point and catches it in a stable position. In many sports, the body is having to move explosively in reaction to a stimuli and then end up in a stable position. Along with improving running economy through improved strength, Ebben believes that there is an increase in injury prevention because of the “benefits of impulsive loading” that are involved in developing “eccentric strength, connective tissue strength and bone remodeling” (pp. 49, Ebben, 2001). When an endurance athlete is performing, often obstacles are encountered, and his/her reaction can decide whether an injury occurs or a successful repositioning.

Unilateral Training for Adolescents?11232871_l

Many of us would agree that safe administration of plyometric exercises is good for adolescents. Brown (2000) states that the degree of fundamental movements or “schoolyard” movements is safe and beneficial for this special population. From a long-term effect of learning plyometric exercises, a benefit that can arise is long-term exercise adherence. In an era where physical education programs are being cut to improve standardized testing, inactivity is at an all-time high, which leads to obesity and type II diabetes.

Hardy et al. (2013) tested the functional movement skills of children throughout four different periods in their life. These skills included: sprint run, vertical jump, catch, kick and overarm throw. For this study, there was a large population size of 13,752, which was taken while these kids were in grades 4,6,8 and 10. The researchers had also a pretty even split of genders throughout the study, which would take away from any gender biases. Along with lack of exposure for girls of certain fundamental movement skills (FMS) as they age, one of the more interesting theories brought up by the authors was how “children who have not mastered basic FMS are more likely to not participate in organized sports because of a lack of basic physical skills” (Hardy et al., 2013). This theory also brought up the possibility that a lack of FMS’ would lead to higher tendencies of obesity. While children should not be constantly subjected to activities they don’t enjoy, physical activity seems to be at an all-time low and childhood obesity is at an all-time high. In order to combat this issue, we as a society need to try to be more creative with the children who aren’t as interested in sports. Funding can be an issue in schools with how much can be appropriated to physical education, but figuring out activities that interest students with undeveloped FMS’ should have a place in research.

From the Author

Even though I was never into the video game Dance, Dance Revolution, I did see the positives of children having to get up and move to play the game. This would be a hard sell to school districts, but if this is what interests children and gets them up and moving, wouldn’t it be worth it? Wouldn’t an hour of a dancing video game or other interactive game be more beneficial than a half-effort hour of walking around a track? If you think about it from a SAQ viewpoint, the movements that individuals make during this game are often on the balls of their feet, front-to-back, side-to-side and behind their backs. These movements could in theory be just as beneficial as structured plyometric training because of the time-under-tension and rhythm factor that is involved. During this game, individuals must keep a rhythm while hitting certain spots on a mat. In my opinion, trying to hit a certain spot while watching a screen that dictates your movement, WHILE dancing sounds like a pretty good exercise that can improve reaction time and burn a ton of calories. Just an idea that would have many barriers even if it were backed researched based evidence.

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Specificity of Training

One of the great concepts of training relates to specificity. This concept has already been discussed in previous sections, but it is so important that it needs its own. “The universal thought in this theory holds that exercises should replicate a movement as closely as possible in the type of muscle action and contraction forces” (McClenton et al., 2008, pp. 321). When athletes attempt to increase their vertical max or lower body strength, force or power, a combination of plyometrics and variable strength training can create a successful program. When analyzing an athlete’s in-game movements, trainers can create programs in the gym that help improve movement patterns. For example, a shot putter doing bench press will be able to gain upper body strength which will help with the event. But an accessory lift that could further improve this athlete’s performance is a standing landmine press. From a movement analysis standpoint, the landmine press is in the sagittal plane instead of the frontal like a military press or transverse like the bench press. The way that the force lines up with the joint allows for less stress on the shoulder. Also, this movement can be organized so the starting and finishing positions resemble the “power position” of the shot put.

Single-leg training can also have benefits for improving an athlete’s reaction time. If a cross-country athlete has to avoid obstacles in order to prevent injury, or change direction to pass another competitor, he or she would perform these movements on a single-leg. It’s not like the athlete would jump off two feet in the middle of a race to avoid a competitor, so why wouldn’t single-leg training be incorporated more in an athlete’s training schedule? Some examples could be bounding or lateral based movements with a reaction component.

Single Leg Aspects in a Dynamic Warm-Up

So before we dive into this topic. What is a warm-up? Why is it important? Typically, a warm-up should prepare an individual for the movements during performance. Science has shown that a combination of dynamic stretches and static stretching provides the body with physiological responses that will benefit performance. Early in the morning the body typically isn’t ready to run a 10k, but after moving around and stretching, the body’s core temperature has risen and now more prepared for the activity in-front of it. The same applied for any performance.

A great example of the perfect warm-up is in soccer. Players line up and perform a combination of dynamic stretches, pause, and do static stretches and PNF stretches, and then go into sport specific warm-ups. These include dynamic movements with cuts, sprints, small steps and other movements that a player would encounter in the field of play. The point of this example is that the warm-up should have components of the athlete’s performance. A soccer player will make cuts, sprint and jump, all of which will often occur on one-leg.

Including Unilateral Training into Your Program Design

The ability for athletes to contort and use their bodies in such unique ways during performance is what makes sport so amusing. We as spectators can only sit in awe as athletes perform windmill dunks and elevate over people to catch footballs. But as strength and conditioning professionals, it is these movements that help us create programs that enhance athlete’s performance and abilities. According to Behrens and Simonson (2011), “the principle of specificity states that for an exercise to be effective, it must contain similar characteristics to the sport” (p.66). It is by trial and error that a strength and conditioning professional can alter his or her program to better suit the athlete during their program.

In the next section, different Unilateral exercises will be reviewed. Please keep in-mind that many of these exercise are advanced or require special equipment. Before incorporating single-limb training with a client, they should be properly advanced through a program to prevent any negative feedback.

Applications


References

Behrens, M. J., & Simonson, S. R. (2011). A comparison of the various methods used to enhance sprint speed. Strength and Conditioning Journal, 33(2), 64-71.

Brown, L. E. (2000, June). Are plyometrics safe for children? National Strength & Conditioning Association, 22(3), 45-46.

Ebben, W. P. (2001, October). Maximum power training and plyometrics for cross-country running. National Strength and Conditioning Association, 23(5), 47-50.

Findley, B. W. (2004). Training with rubber bands. Strength and Conditioning Journal, 26(6), 68-69.

Hardy, L. L., Barnett, L., Espinel, P., & Okely, A. D. (2013). Thirteen-year trends in child and adolescent fundamental movement skills: 1997-2010. Medicine & Science in Sports & Exercise, 45(10), 1965-1970. doi:10.1249/MSS.0b013e318295a9fc

Lorenz, D. S. (2014). Variable resistance training using elastic bands to enhance lower extremity strengthening. International Journal Of Sports Physical Therapy, 9(3), 410-414.

McClenton, L. S., Brown, L. E., Coburn, J. W., & Kersey, R. D. (2008). The effect of short-term VertiMax vs. depth jump training on vertical jump performance. Journal of Strength and Conditioning Research, 22(2), 321-325.

National Strength and Conditioning Association. (2008). Essentials of strength training and conditioning (3rd ed.). Champaign, IL: Human Kinetics.

Rhea, M. R., Peterson, M. D., Lunt, K. T., & Ayllon, F. N. (2008). The effectiveness of resisted jump training on the VertiMax in high school athletes. Journal of Strength and Conditioning Research, 22(3), 731-734.

Santana, J. C. (2001). Single-leg training for 2-legged sports: Efficacy of strength development in athletic performance. Strength and Conditioning Journal, 23(3), 35 – 37.

Wallace, B. J., Winchester, J. B., & McGuigan, M. R. (2006). Effects of elastic bands on force and power characteristics during the back squat exercise. Journal of Strength and Conditioning Research, 20(2), 268-272.

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