The recent popularity of one leg resistance training, such as lunges and pistol squats, and their relevance to sport is easy to visualize. Whether you are trying to sprint or change directions faster, it is easy to connect how a single leg weighted exercise would enhance your sports specific movements. Unfortunately, recent research has questioned this natural assumption.
A study by one of the country’s foremost strength and conditioning professors, Jay Hoffman, found significant differences between the power of the dominant and non-dominant legs in 62 college football players. However, these same athletes showed no difference in agility times between dominant and non-dominant sides. The authors suggest this finding is due to a threshold power level that prevents further improvements in agility time, meaning your power/strength levels can only progress up to a certain point in each leg.
The theory suggested by the authors is limited because this study only examines college football players, which is only relevant to elite athletes. The general population would be best served by pursuing these exercises and a variety of other modalities (such as Pilates, Kettlebells, etc.). We have a similar population to the aforementioned study at Sparta, training only high school, college, and professional athletes, so their single leg strength threshold is also achieved quickly.
At Sparta, we still do single leg resistance exercises, and our athletes achieve much of their initial improvements in strength and running performance by performing lunges and other one leg movements. However, after an athlete achieves a specific percent of their body weight in this exercise, we concentrate on mostly double leg strength movements, such as squats and the Olympic lifts as these exercises have a much higher threshold for improvements. We also focus on the skill of running a fast agility or sprint by repeatedly running the steps over and over again (see Sparta Point 7/8/09).
So if you’re competing against our athletes, please continue to perform single leg resistance training after you have achieved a large training history and throughout your career, well after you have passed that single leg threshold.