Editors Note: My new site is now at www.just-fly-sports.com Check it out for a wealth of information on jumping higher and running faster, all backed by research and practical experience!
So what does rubber bands have to do with anything? Well here is why they are so great........they are very effective modulators (or altering agents) of force applied to them. Think about it, say you want to shoot a folded paper bullet across the room at a classmate, co-worker, or even your boss. You can't throw the paper wad, because you will never be able to impart enough force mechanically to get it to fly fast or straight enough to do any sort of damage. So what do you do? You whip out your rubber band that was holding your notecards together and use that to shoot the paper projectile. But how does that work? It works because a rubber band is a SPEED amplifier. The rubber band cannot produce force on its own, correct? But once you put force into it, it will give you a massive return in terms of speed.
The human body is the same way! Your muscles are simply not capable of producing the speed required for the incredible dynamic movement that the human body is capable of on their own. They need a little help from their friends so to speak.
Now let me give you a quick evolution of my thoughts on the importance of tendons over the years. My senior year in college was my first year that I began to realize the importance of tendons through reading some of the works of inno-sport. The majority of their preaching was on "stiffness" (yes, I know, "That's what she said"). Anyways, their basic tenant was that muscles that could produce large amounts of force without stiff tendons were not functioning well, because the slack would weaken the movement significantly. I maintained this view until my first year of graduate school a year later. In my first research class, I wrote a lengthy paper on human elastic structures. Once I really began to dig into the research I found several interesting findings. Perhaps the most important was that in many cases, it is not how stiff a tendon is that is important, but how "compliant". Compliance is basically the ability of a tendon to stretch under stress and then return to its original position. Studies have proven that the fastest 100m sprinters have vastus lateralus (quadricep) tendons which are more compliant than slower runners. Although these specific studies seemed to suggest that compliance is the most important facet of tendons, common sense would say that the optimal compliance of a tendon is based on its use. Anthony Blazevich, PhD, has stated that joints that have small ranges of motion (ankle) will benefit from tendons that are stiffer, while joints that go through larger ranges of motion (hip) will benefit more from tendons which are more compliant. I think that this makes good sense.
Now before you go and start working on your ability to do the splits, here are a few quick definitions and ideas.
PEC: Parallel Elastic Component of Muscle. This refers to the section of connective tissue which surrounds muscle. This includes the fascial sheath of the muscle, as well as the sarcolemma surrounding the muscle fibers. This component is brought into play when the muscle is stretched beyond its normal length, aka, static or dynamic stretching.
SEC: Series Elastic Component of Muscle: This refers to the tendons, and elastic elements within the muscle, such as titin. This component is brought into play when the muscle is producing force, aka. sprinting or jumping.
Idea: Fast twitch muscle is by nature, more flexible than the collagen-heavy slow twitch muscle.
Idea: Slow twitch muscle is able to hold its cross-bridge attachments for a longer period of time than fast twitch muscles, which can still allow for explosive movement by use of tendons, it just takes longer.
Idea: Research has shown that sustained amounts of heavy weightlifting can result in increased tendon stiffness.
Idea: Research has also shown that although heavy weightlifting can stiffen up tendons, extended time under tension in weightlifting can lead to more compliant tendons, particularly the SEC (the important part of the tendon).
Now here is what it all comes down to: Tendons are extremely important in human movement. They are very specific when it comes to their job description. This is why it is vital in any sport to make the Primary Sporting Movement the main object of affection. This is also probably why anyone who has lifted weights for an extended period of time without doing adequate elastic work (sprints, bounds, depth jumps, multi-jumps) will notice a severe strain on their running vertical ability, particularly in the single leg category. I am not bashing weightlifting though! It is very important to reach the ultimate genetic potential of any athlete, but whenever weightlifting becomes the #1 training means of an athlete for too long of a period (I would say 2-3 months, it starts to bring with it some negative effects on dynamic movement). Also, the more "fast twitch" the movement, the more "weightlifting only" may have a detrimental effect on the movement. In other words, sprinting will take a bigger hit than a standing vertical off two feet.
Secondly, people who are "slow twitch" dominant can still "get up". Anyone can make big increases in vertical by getting stronger and gaining jumping efficiency. However, slow-twitch dominant individuals are going to spend more time on the ground when jumping, and thus won't be quite as good shot blockers or high jumpers than the more fast twitch dominant individuals. As the "idea" above stated, slow twitch muscles can still produce large force output, but they need the tendons to do it, and they take longer to get it done. I beleive a study done on volleyball national team whose average standing vertical jump was in the high 30's demonstrated a fast twitch ratio of 55%. This is only slightly above average. Volleyball players have been proven, however, to spend significantly longer times on the ground when preparing to jump compared to say, track and field athletes.
My third point is based on the fact that extended time periods of weightlifting sets can lead to more compliant tendons. New and exiting research has been coming out which show that sets of around 10 can be better than sets of 3-5 regarding the development of sprint speed. (Obviously you would not use one set-rep scheme exclusively) Perhaps this has something to do with the tendons? Also, if you have ever wondered about the principle of Joe DeFranco's 50-rep rhythm squats, this might be a good answer.
Finally, another direct and applicable message of this post is to spend some time training in the stretch range of movement. An exercise that I really like for sprinting is the osciallatory isometric hip flexion movement as perscribed by inno-sport. Here is a link
http://www.inno-sport.net/Strength-Endurance.htm
The exercise is OI HF squat. Let me confirm here, that just stretching alone will not significantly increase the power output of the tendons. You need to be specific in their training, and that means loaded training in the stretch range.
Good luck!
Joel Smith, CSCS (at least until my CEU's are due)
THE ORIGINAL RUBBER BAND MAN! Dick Hartzell