Bilateral strength development, the sacred cow. Timing decelerations, a possible tool.

This article involves two specific questions regarding athletic preparation, which I have been contemplating for a while and have not yet found an answer to…

Question 1: Bi-lateral strength development, the sacred cow

In sport levels where functional minimums for competition have been achieved (e.g. arguably collegiate and semi-pro, but definitely pro sports), the priority from a physical preparation standpoint becomes overall health, readiness and durability as a base for technical, tactical and psychological capacities to thrive and be enhanced. Reducing or minimizing athletic injuries becomes the greatest and most important challenge for the physical preparation coach.

It is no secret that single-leg instability predicts lower limb injuries. In theory, we understand that in the absence of equally dosed unilateral strength stimuli, bilateral strength development increases the magnitude (or width) of the bilateral deficit. On the contrary, unilateral strength development transfers positively to bilateral strength adaptation. In addition, given that bilateral strength exercises do not recruit key knee and hip stabilisers to the same (if any) extent as their uni-lateral counterparts, this would mean that bilateral strength development may also increase the difference in strength characteristics between knee and hip stabilizers and agonist muscle-tendon units; with this may come an inability to effectively control (unilaterally) the force produced bilaterally. Assuming the above points, developing bilateral strength would make athletes less stable unilaterally and thus, more susceptible to injury. So, from this thinking, the argument of a greater neuromuscular strength stimulus/adaptation with heavy bilateral training would be incongruent (i.e. because it promotes a deterioration of unilateral stability, an asymmetry between lower limb stabilizers and agonists and has little to no proprioceptive component).

So, what is the point of lower body bilateral strength training at all? What is the true reward of developing lower body bilateral strength at the expense of the abovementioned costs? What is the benefit of enhancing bilateral strength in sports where athletes are almost exclusively exposed to unilateral movements/positions (e.g. team or court sports)?

Unless one is perfectly certain that the balance between unilateral and bilateral strength development is equal or favours the unilateral component, the inclusion of lower-limb bilateral strength training may be more costly than profitable. Is there something I am missing out on?

Question 2: Timing decelerations, ideas for more tools in the box

A similar thought process prompted me to consider the importance of deceleration abilities in athletic performance. Again, it is no secret that poor deceleration mechanics, particularly if high-speed efforts precede these, predict lower-limb injuries. In the athletic preparation practice, there is a big focus on speed and acceleration development, and this makes sense. Generally speaking, the faster an athlete is, the greater chances he will have of making an impact on the field of play. To this end, lots of work and time goes into timing accelerations, assessing max velocities, monitoring high speed zones, etc. Similarly, a great deal of research in sports performance has gone into investigating the effects of sprinting on enhancing performance and reducing hamstring injury risk, optimizing top end speed sprinting mechanics, optimizing acceleration performance and so forth. And this is probably due to the big track and field focus, which has been present in athletic preparation from ancient times. Please don’t get me wrong, this is good, it is great in fact. The degree of attention to detail and such technical training interventions to optimize movement efficiency from the track and field world is exemplar and should continue to be used to inform physical preparation coaches. However, is it all? This approach biases the concentric side of speed development (i.e. sprint times, sprint speeds), which makes total sense in track and field. But what about the eccentric component? Particularly in such biomechanically unpredictable sports (e.g. team and court sports), deceleration and a rapid transition from deceleration into acceleration in an alternative direction is pivotal to performance and injury resilience. Also, what about the high neural demand associated with decelerating? Wouldn’t a better understanding of what this looks like in the field of play enhance the physical preparation coach’s practice?

So, I guess my question would be does anyone time decelerations? And as a disclaimer, I have not, this is just me contemplating… We know that enhancing deceleration abilities and optimizing mechanics can have important implications for injury prevention, but this is undervalued and doesn’t get the level of consideration it deserves. I mean, I was taught a few years ago to coach “quarter squat position” full stops, and this make sense from the perspective of engaging the gross hip muscles in the breaking action. Is this robust or sustainable? How do we know if we are not timing or observing the decelerations? Importantly too, how do we know if decelerating quicker or slower and over a larger distance prevents injury better of creates greater adaptation to muscle-tendon structures? Of course, athletes need a greater distance to fully decelerate when sprinting at top speeds, but this may not necessarily be optimum following short / sharp accelerations. I don’t really know, to be honest.

How? Again, this is me just brainstorming and contemplating… High speed pyramids may be a good option (e.g. 10m accel., 10m speed maintenance, 10m deccel.). If you are like me and you use video a lot, there is an application called “stopwatchcam”, which features a camera and a stopwatch, to time sprints. By saving the video, the coach can then look at the video frames and work out sprint times pretty conveniently. Anyways, using such a tool could allow to time deceleration times, deceleration rates, the coach can look at specific movement strategies at different pre-deceleration-onset speeds, joint angles, number of steps taken to decelerate and in the longer term, the coach can start to make internal (squad-level) associations with deceleration related injuries. I know this sounds like a heck of a lot of work, but these are just ideas that could provide a greater level of attention to detail (with minimum time invested) to enhance or inform the physical preparation strategies.

Thanks for taking the time to read.

Key readings referenced in this article

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2. Cerulli, G., Benoit, D. L., Lamontagne, M., Caraffa, A., & Liti, A. (2003). In vivo anterior cruciate ligament strain behaviour during a rapid deceleration movement: case report. Knee Surgery, Sports Traumatology, Arthroscopy, 11(5), 307-311.

3. Cochrane, J. L., Lloyd, D. G., Buttfield, A., Seward, H., & McGivern, J. (2007). Characteristics of anterior cruciate ligament injuries in Australian football. Journal of science and medicine in sport, 10(2), 96-104.

4. Connolly, F., & White, P. (2017). Game changer. Simon and Schuster.

5. Edouard, P., Mendiguchia, J., Guex, K., Lahti, J., Samozino, P., & Morin, J. B. (2019). Sprinting: a potential vaccine for hamstring injury. Sport Performance & Science Reports, 48, v1.

6. Kovacs, M. S., Roetert, E. P., & Ellenbecker, T. S. (2008). Efficient deceleration: The forgotten factor in tennis-specific training. Strength & Conditioning Journal, 30(6), 58-69.

7. Mc Bain K, Shrier I, Shultz R, Meeuwisse WH, Klügl M, Garza D, Matheson GO. Prevention of sports injury I: A systematic review of applied biomechanics and physiology outcomes research. Br J Sports Med 46: 169–173, 2012.

8. Nijem, R. M., & Galpin, A. J. (2014). Unilateral versus bilateral exercise and the role of the bilateral force deficit. Strength & Conditioning Journal, 36(5), 113-118.

9. Riva, D., Bianchi, R., Rocca, F., & Mamo, C. (2016). Proprioceptive training and injury prevention in a professional men's basketball team: a six-year prospective study. Journal of strength and conditioning research, 30(2), 461.

10. Sell TC, Clark NC, Wood D, Abt JP, Lovalekar M, Lephart SM. Single-leg balance impairments persist in fully operational military special forces operators with a previous history of low back pain. Orthopaedic J Sports Med 2: 2325967114532780, 2014.

11. Škarabot, J., Cronin, N., Strojnik, V., & Avela, J. (2016). Bilateral deficit in maximal force production. European journal of applied physiology, 116(11-12), 2057-2084.

12. Vint, P., & McLean, S. (1999, October). Maximal and submaximal expressions of the bilateral deficit phenomenon. In Proc.

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