Original article written by James Forster, Aaron Uthoff and John Cronin.
Background
Change of direction (COD) movements are required in many field and court sports. Therefore, S&C coaches are interested in selecting exercises to improve the strength and power of the muscles to enhance these actions. A challenge is to find exercises that are specific enough to match the COD demands of the sport. This article appeared in Strength and Conditioning Journal, which is a professional journal rather than a research journal. The article was presented in a regular column called “Exercise Technique”, where an exercise is described in detail.
What the authors did
The exercise is called a Medicine ball rotation with lateral rebound jump (MBR). In line with the exercise technique column, the authors started with the background to the exercise, described the technique, stated the muscles involved, listed 7 common errors, and finished with some practical applications.
What the authors found
The MBR involves a lateral rebound jump with postural control by including a torso rotation while holding a medicine ball. The best way to understand the movement is to view the photo sequence below.
You can see that the rotation of the medicine ball towards the landing leg and then back to the other side will overload the torso muscles while also providing extra weight to the body to overload the leg extension. The landing on the leg and subsequent hip, knee, and ankle extension means the exercise is plyometric in nature and is intended to relate to COD mechanics by including stretch-shortening cycle actions of the upper and lower body, to decelerate and reorient the body in a new direction.
Limitations
The exercise is meant to simulate a COD action found in multidirectional field and court sports. While it appears specific to one lateral movement, you must remember that in many sports, agility movements are complex and often involve varied techniques such as sidesteps at different speeds and cut angles, cross-over cuts, and spins. Therefore, this exercise must be used in conjunction with many others to cater for the multidirectional nature of many sports. Another limitation is that the description of cueing wasn’t very clear. The authors said an instruction to minimise ground contact time (GCT) will increase RSI compared to cueing for jump height. A better explanation would be to say that there is a trade-off between lateral jump distance and GCT, where emphasising a shorter GCT will lead to shorter lateral jumps, and a “sweet spot” should be found. It would have been good to include some data on actual GCT in the exercise because this could be related to COD demands in sport.
What this means for coaches
The authors suggested a repetition range of 3-6 per set with more reps with a lighter medicine ball (e.g. 3 kg), and less reps with a heaver ball (e.g. 10kg). Coaches should be aware of the common faults listed and monitor technique.
Reviewer’s comments
The idea of using a medicine ball to overload COD mechanics is a novel one and allows coaches to use readily available exercise equipment. I like the addition of trunk rotation in the exercise to overload trunk stability. Although the authors didn’t state this, rotation of the trunk away from the new direction of travel in sidestepping is associated with an increased risk of anterior cruciate ligament rupture. Therefore, this exercise is unique in that it overloads both leg extension and trunk stability, and potentially has an injury prevention benefit. Keep in mind that anti-rotation of the trunk is actually what we are looking for, so this exercise could also be performed with the medicine ball held in front of the chest throughout the whole movement (i.e. no rotation).