One leg training for Sport: effectiveness in developing strength for athletic performance

Current training philosophy

Strength is one of the most, if not the most emphasized, element in the development of athletic performance. Most athletic trainers are of the opinion that one is never strong enough. Therefore, this philosophy pushes athletic trainers to load the weights raised by their athletes as much as possible to develop superhuman strength, especially in the United States. The idea seems to be that "if the weights raised by my athletes are higher than those of the other team, if my athletes are stronger, my athletes will win". Any person involved in the sport for quite some time has been able to see that this current of thought is totally wrong. We have seen athletes who raise remarkable loads in the weight room have less strength, power and speed in the playing field, compared to opponents who could not lift the same loads, in the gym. The world of athletic training has been heavily influenced by the philosophy of bodybuilding. Traditional multi-joint movements of bodybuilding have dominated the paradigms of strength development. Additionally, the market for isotonic machines has attempted in many "interesting" ways to develop strength. Due to the strong influence of philosophy based on muscle hypertrophy, squats and leg presses, in one way or another, they are still the strong point in most training programs for athletes. Often, outside of periodization considerations, these exercises continue to dominate the cycles of strength development.

Biomechanics of Sport

If we look at the biomechanics of the lower limbs, in almost all sports, we can see that in most cases, the production of force is generated by a single leg.

Racing and quick changes of direction, which are fundamental in many sports, are skills that require strength generated by a single leg. Even in situations where both feet are on the ground, weight distribution will often be one-sided. Laws of physics such as inertia, momentum and impulse, characterize these environments. Furthermore, these physical components have to deal with 360 degrees of freedom of movement and the reaction forces with the ground. These are the elements that the athlete must train to offer the best performance and which are the basis of many sports. Since the specificity of training is the principle that guides the methods of increasing athletic performance, it would be prudent to consider these simple observations. If in sport the generation of force involves unilateral movements, multi-joint movements, dynamic multi-planar stabilization and production of force from the ground, then these should not be the principles behind the development of lower limb strength?

Multiplanar nature of the kinetic chain: effects of unilateral lower limb performance

Observing the kinetic chain in action, allows us to see how the reaction forces are transmitted through the lower limbs and core muscles to promote fast and explosive movements. The various angles of the body that result from moment manipulation require that an athlete be able to produce strength on one leg, concentrically, isometrically, and especially eccentrically. This dynamic multiplanar environment, in sport, requires that the individual leg be applied strength in a proprioceptive manner. The support leg must control the forces (concentrically, isometrically and eccentrically), while the corners of the leg joint are constantly changing in all 3 planes of movement. This stimulation of the lower limbs is rarely addressed by a perspective of strength from today's training methods.

Unilateral training of the lower limbs: Training, programming and safety considerations

The training of a single high-intensity leg should have a priority position in sports that require running and / or rapid changes of direction such as football, basketball, American football and many others. Leg presses and one-leg lunges are a good start, but it doesn't end there. We think of the different angles that the leg creates and the forces that act on it. Of note, the position of the foot while force is applied to the ground. This means that the athlete must learn how to apply force while the foot, knee and hip are loading (pronation system) or discharging (supination system), in all movement planes. Between the phases of loading and unloading of force production, the athlete needs proprioceptive stabilization. Stabilization training combines the production of eccentric and concentric forces and this must be trained to achieve optimal performance. Exercises like squats on one leg with dumbbells do not require heavy weights to create a high intensity workout. Training on one leg also makes sense, if viewed from the point of view of an athlete's health and durability. The degenerative effects due to years of athletic abuse and heavy leg workouts can result in knee, lumbar and even knee pathologies. Not only does one-leg training offer a method for developing usable strength, but the weights to be supported are not high (in contrast to the 150-300 kg of squats or 300-500 kg of leg-press) and the positions not they are so extreme (for example the complete squat position, associated with the Olympic lifts). Due to the light weights and the more functional positions used in this unilateral training approach, one-leg training is essential to prolong an athlete's career while improving his performance.

Future directions for research and observation

There is no doubt about the effectiveness of traditional lifts to achieve various strength and hypertrophy factors (increased work volume, hormonal response, etc.). However, when the mechanisms behind injuries or dissipation of force production are examined, it is immediately evident that a single leg dominates in the great majority. Therefore, if the principle of "specificity" really dominates the paradigm of performance improvement, then, proprioception, heavy training on one leg will produce extraordinary results, without extreme positions or loads. This one-sided approach to training will not only improve performance but will also prolong the athlete's career.