Improve Sprint Performance By Correcting Leg Strength Imbalances

In this video we will discuss some ideas for how sprinting workouts and strength training can be modified to balance your force and power capabilities for both of your legs so you can optimize performance and minimize risk of injury, both on the track and in the gym.

Training Can Create Imbalances

When athletes sprint and jump, they tend to favor one leg over the other. Over the course of thousands of sprints and jumps, the habit of always starting on the dominant leg creates an imbalance in the ability to generate neural drive and force output through the non-dominant leg, and I believe that this asymmetry can become pathogenic over time.

While asymmetries will always exist in the human body, we should do our best to be as balanced as possible both as a way of preventing injury and to maximize performance. At a basic level, single leg and split stance exercises can help to bridge the gap, but I think more needs to be done in order to balance your abilities between your two legs.

By working to develop balance in both legs, we can not only bridge the gap in performance between the two limbs, but also challenge the brain to coordinate these movements in a manner that is slightly different from when we only emphasize our dominant leg. This gives us an opportunity to further develop ourselves as athletes, both on the level of tissues as well as coordination and movement skills.

How Do You Test For Imbalances?

There are a few simple ways you can test for imbalances in your leg strength and power.

  • Time your 10 meter sprint for 4-6 sprints, alternating which leg you start from. Look at average times, best times, and slowest times to determine if you have a significant imbalance. This will assess imbalances as they relate to the sprint start.
  • Test your single leg vertical jump using the MyJump2 app. If you have a significant difference in your jump heights, you have an imbalance. This will test imbalances as they relate to vertical force production.
  • Test your single leg broad jump using a tape measure, taking note of which leg you can jump further with. This will test imbalances as they relate to horizontal force production.
  • Perform a single leg RSI test using a slow motion camera. Take your flight time and divide it by your contact time, and see which leg struggles more to generate a high RSI. This will test imbalances as they relate to vertical leg stiffness.

Creating Balance At The Track

When we perform sprint training, throws, and plyometrics, we can create variability in our training while also promoting symmetrical balance in the body based on how we train and the exercises we select.

Sprints

The easiest way to ensure both your legs are equally capable is to alternate your start leg during your sprints. When timing myself, I noticed that starting on my non-dominant leg led to 10m sprint times which were consistently one tenth of a second slower than when I start with my dominant leg forward. Not only were the times slower, it felt like my brain was struggling to get my body moving when starting on my weaker leg, and it looked slow on video.

By alternating which leg you start with you can improve the neural drive and coordination of your non-dominant leg while also minimizing injury risk. I notice that when I add a lot of block starts and crouched starts into my training without alternating legs, I tend to get irritation in my anterior hip compartment and proximal adductor tendons. The repeated use of the same starting stance can cause chronic overuse issues in these areas, but this can be prevented by alternating your start leg especially throughout your off-season and pre-season. I would suggest regularly alternating your start leg whenever you sprint earlier in the year, transitioning to mostly using your dominant leg the closer you get to competition. 

Plyometrics & Throws

With plyometrics, alternating which leg you start with as well as using single leg options are one way to encourage equal development in both legs. For example if you are doing alternate leg bounds from a standing start, you can switch your start leg each repetition. Alternatively, more advanced athletes can do single leg bounds where the athlete repeatedly makes contact on the same leg as they move forward.

With explosive medicine ball throws, single leg and split leg options can be used as a way to add variability to your training while also helping balance your leg and core development. For example a single leg throw forward or a split leg rotational throw forward can be used for these purposes.

In The Gym

In our strength and jump training we perform at the gym, we can once again use single leg and split leg variations of movements as a way to create a novel stimulus and also promote balance and symmetry in the body.

As far as lifts are concerned, single leg deadlifts, single leg RDL’s, lunge variations, step up variations, heavy sled pulls, and single leg isometrics are some of the many options available to us. Make sure that when performing a lift that you concentrate and focus on performing the exercise as similarly as possible on each leg, not giving in to the feeling of being lazy on your weaker leg.

Jumps onto soft plyo boxes offer us a good option for working on both static and dynamic start movements, such as a single leg box jump either with or without a countermovement. Focus on staying on the ball of your foot with a stiff ankle as you jump, as this might help encourage transfer from this general jumping ability to something that can be used when performing starts or sprints in general.

Interventions Should Target Your Biggest Imbalances

If you perform the tests mentioned earlier, you might find that you have more significant imbalances in one test and less imbalance in another test. This information can inform you as to what you might need to work on the most.

For example if your 10 meter sprint times are within a couple hundreths of a second but your single leg RSI values are drastically different, you might be better off focusing your efforts on improving single leg vertical stiffness and then retesting at a later date.

In contrast, if you find that all of your tests show imbalances between the two legs, you can take a more general approach and incorporate both fast and slow, vertical and horizontal single leg movements, as well as alternating your start leg when you sprint.

Conclusion

You do not have to get overly cerebral with setting up your training, but you should take a look at your leg imbalances through a variety of simple tests so that you can find opportunities for further development and injury prevention.

Depending on your needs you can alternate your starting leg when sprinting and jumping, perform single leg lifts, and perform single leg jumps. Even if your imbalances are not large, you can still benefit from incorporating these different exercise types in your sprint training program.