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“It was correctly noted that heavier implements can have a positive influence on an increase in physical abilities and a negative one on technical mastery.”
--Anatoliy P. Bondarchuk, Transfer of Training in Sports
One of the biggest problems I see in sports performance today is the addition of external resistance to technical skills that are vital to an athlete’s success in his or her sport. Clear examples of this can be seen in the addition of doughnuts to a baseball player’s bat while he is in the on-deck circle or golfers swinging with heavier clubs than they are accustomed to while warming up. In the video below, you can see the danger of this from a performance perspective, courtesy of Sports Science.
While the bat and the club are great examples, I would also like to consider two movements that are found in almost every sport: running (or sprinting) and jumping.
Yes, both sprinting and jumping are skills and the performance of each movement can be improved by simply improving the technique of each respective movement. The problem from here on out is that for me to give actual recommendations regarding what you should do as an athlete, coach, or trainer would be both ignorant and futile. Instead, I would like to discuss what I see as the pros and cons of some of the more mainstream forms of adding resistance to the sprint and the jump.
Weighted Vest
- Image courtesy of http://www.canterburysports.co.nz/
The weighted vest is one of the most common tools used when someone wants to add resistance to their vertical jump training. Rarely have I seen a weighted vest used as a tool to improve sprint performance, although it may be worn for conditioning, which is distinctly different due to the intended adaptation that is being trained for.
One problem I see from a technical standpoint is that most weighted vests are too heavy for the individual using them if technique is not to diminish. According to Bondarchuk, “The portion of maximum intensity training loads used in the process of mastering technique should be about 10%.”[1]
Now, as a disclaimer so as not to completely take the quote out of context, Bondarchuk wrote this book while studying track and field athletes and, in particular, this quote was referring to throwers using heavier implements. For the sake of this discussion, though, I know I have seen research elsewhere of the “10% rule”, but am failing to find said research to quote at this moment. Regardless, it is an interesting point to consider.
So, in terms of using a weighted vest for vertical jump training, what does this mean? Well, because you are just simply adding weight to the body it is fairly easy to calculate. Much like the increasing the weight of the implements by 10% in Bondarchuk’s research, it would seem that if you were to use a weighted vest that is less than or equal to 10% of your body weight the mechanics of jumping would not be altered, or at least would have the greatest opportunity to not be altered.
To dive into why this is would be to go outside of the scope of this article, so for now I will leave it at the specific sequence of muscular contraction that takes place under normal conditions of jumping with only body weight is altered when external resistance is added. According to Bondarchuk, this alteration is significant enough with resistances over 10% to deviate the mechanics of the movement from what would be considered optimal.
Resistance Bands and Tubes (Accommodating Resistance)
- Image courtesy of http://www.diamondfitnesssystems.com/Page_Vertimax.htm
A resistance band, as I am defining them here, is essentially a big rubber band that provides increased resistance the farther you stretch it. Bands do not have a starting or stopping point and instead are basically a circle of rubber while a tube has a distinct stopping and starting point and is more of an elongated cylinder. From this point forward, when I refer to a band or tube, I am speaking to characteristics of both.
The accommodating resistance is a unique aspect to the resistance band when compared to the weighted vest or weights in general. Another variable of the resistance band that can be manipulated to your advantage is that you can easily create a line of force that is independent of gravity. You always have the force gravity pulling straight down, but with the resistance band you can have another force pulling in another direction, whether that be straight back (posterior), as is most commonly seen with sprinting, or at an inferior/oblique angle, among an infinite amount of other possibilities. An example of an inferior/oblique line of force would be connecting bands to a belt worn around the hips and then to fixed points on the ground lateral to the body, much like what can be seen when using a VertiMax Jump Trainer.
- The VertiMax V6
When you have two or more lines of force acting on a single point of application, you get something called a resultant. With a resultant, you are taking the relative pull of all the lines of force and creating one new line of force that is directionally somewhere in between the original lines of force. Take the VertiMax, for example. You have gravity pulling straight down and then you have tubes that are strapped to the knees, hips, and wrists pulling towards the ground at an inferior/lateral angle. Each one of these points where the tubes are strapped is going to have a separate resultant. Generally speaking, each resultant will be found somewhere between the medial aspect of the tube and the lateral side of the body, with the angle of the resultant unique to each point of application (where the tube is strapped). Not only that, but the angle of each resultant will change as you perform any and every movement due to the changing limb position and, in turn, the point of application relative to gravity and the tension of the tube.
Okay, so there is a lot of technical verbiage in there. Breaking it down, I am basically saying that by adding to a movement a band or tube that is not specific to each joint and the direction of the movement, you are now adding a resistance that is alien to the movement itself. Subsequently, the muscular recruitment must be altered in order to keep the mechanics the same as the original movement. If it isn’t, then mechanically you will not be able to produce the same movement because the forces that you have to overcome are different.
Putting this all together, I cannot sit here and tell you if it makes sense for you to add resistance to these movements that you use in sport. But, I can say that if you don’t understand how to properly apply forces to the body you are shooting in the dark when it comes to whether or not you will be able to create your intended adaptation. Understand that by adding something in, such as another form of resistance, you are likely giving something up in the form of technical competency from a neuromuscular and/or mechanical perspective. I am not saying that training with these tools will not help you improve the gross performance of the movement or that there isn’t a place for them in a training program, but rather that you may be sacrificing something along the way. Understand the individual you are working with, understand the risk to reward ratio of what you do, and choose your methods and tools accordingly.
Charlie Cates, CSCS
Self Made®, Owner and Founder
Charlie Cates is a strength and conditioning specialist and the owner and founder of Self Made® (http://selfmadefitness.com/) in Chicago, IL. He has worked with competitive and everyday athletes of all ages and ability levels, from 9-year-old kids to NFL MVP’s. He can be reached via e-mail at charlie@selfmadefitness.com.
This article may be reproduced with biographical information intact.
[1] Bondarchuk, Anatoliy P. Transfer of Training in Sports. p. 178
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