How to jump train your glutes (or your quads).
A long running theme in this blog is the concept of moving beautifully. Specifically we all deserve to move beautifully for two reasons. First because moving beautifully looks great, instills internal confidence and makes a fantastic impression on everyone around us. And second because moving beautifully is a huge asset to our health in that it helps to prevent injury and build functional strength.
Today I want to draw attention to a movement pattern in the context of building functional strength. It will be a little lesson in body mechanics that we can all take into our training as an example of how understanding the basics in two different positions can help us to target specific muscle groups in a training exercise.
Many folks will have heard of plyometric training. This is an exercise type that improves power - our ability to generate force quickly. For the lower extremity (legs), a strength exercise would be the squat, slow, steady, with lots of force. A power, or plyometric exercise would be the countermovement jump, which looks very similar in nature but is done with speed. It is the speed of the jump that allows us to (briefly) escape the bonds of gravity as our body leaves the floor. By contrast the slow and steady squat does not generate enough velocity to overcome the constant downward acceleration of gravity.
Multiple muscle groups contribute force to the jump movement, including the quadriceps, gluteals and hamstrings and calf musculature. Interestingly, researchers have looked at how a change in body position alters the relative contributions of these muscle groups to the movement. This research has suggested that landing and launching with the trunk in a more flexed position (chest angle more forward with the pelvis projected back) elicits a stronger contribution from the glutes (your bum). Conversely landing and launching from a more erect trunk position elicits a stronger contribution from the quadriceps muscles (the front of your thighs). If you are trying to visualise this, think of the trunk flexed jump as being more like a basketball player launching from a crouched position as she drives toward the basket, while the trunk erect jump is more like a volleyball player jumping for a block from his position at the front of the net. Can you visualise the difference?
Take a look at the video above, in it I describe briefly the reason why this simple change in trunk position helps us to target specific muscle groups for training. It is a question of physics. As we angle forward with our trunk, our center of mass moves further away from the hip joint center and closer to the knee. This creates a longer moment arm against which the hip extensor muscles (the glutes primarily) must work - in other words the glutes have to create more torque to straighten the hip. Similarly, a more erect trunk moves the center of mass away from the knee joint center and closer to the hip. This creates a longer moment arm against which the knee extensor muscles (the quads) must work - in other words the quads have to create more torque to straighten the knee.
We can use this simple physics principle to make our plyometric training program specific to the glutes with a trunk flexed countermovement jump, or specific to the quads with a trunk erect countermovement jump. Have a look at the video and try these two variants out for yourself!
Understanding the mechanics of our movement and using this understanding in our daily actions is part of what I mean as I refer to moving beautifully. I hope you have fun using this gym hack to show off your beautiful movement today. Enjoy!
Further reading (if you really want to impress your friends!)
Blackburn, J. T., & Padua, D. A. (2009). Sagittal-plane trunk position, landing forces, and quadriceps electromyographic activity. Journal of Athletic Training, 44(2), 174-179.
Powers, C. M. (2010). The influence of abnormal hip mechanics on knee injury: a biomechanical perspective. journal of orthopaedic & sports physical therapy, 40(2), 42-51.
Sheehan, F. T., Sipprell III, W. H., & Boden, B. P. (2012). Dynamic sagittal plane trunk control during anterior cruciate ligament injury. The American journal of sports medicine, 40(5), 1068-1074.
Shimokochi, Y., Ambegaonkar, J. P., Meyer, E. G., Lee, S. Y., & Shultz, S. J. (2013). Changing sagittal plane body position during single-leg landings influences the risk of non-contact anterior cruciate ligament injury. Knee Surgery, Sports Traumatology, Arthroscopy, 21(4), 888-897.