The Triathlete's Holy Grail: Part I
Any endurance athlete, and especially an Ironman triathlete, should have one very specific physical objective during the race: to maximize wattage (power) and speed (velocity) while simultaneously minimizing muscular fatigue and depletion of energy stores. Let’s call this lofty objective "Triathlon's Holy Grail" or THG. All particulars aside, the athlete who achieves THG the most efficiently will be the first to cross the finish line. The athlete who only achieves the first part of this goal, maximizing wattage and speed, will accomplish a big ol' DNF (did not finish), while the athlete who only achieves the second part of this goal will accomplish a FLFL (cross the finish line with a flashlight).
Applying a combination of basic biomechanics and exercise physiology to the three components of the race (swim/bike/run), a triathlete can accomplish THG with optimum efficiency. In this four part series, I'd like to explain 1) how to use the basic biomechanical relationship between mechanical levers and torque to positively affect three keys to efficiency in the three specific components of swimming, biking and running and 2) how to use the basic physiological relationship between the body's energy systems and muscle fibers to prepare for peak performance.
First, let's briefly discuss the relationship between a mechanical lever and torque. The human body is a perfect example of a series of levers (bones) that are attached to different points of rotation (elbow, knee, hip, back, etc.). For example, imagine that you are holding your running shoe in your hand, with your arm outstretched completely straight away from your body. In this case, the shoulder is the center of rotation, the lever is the length of the arm between the shoulder and the hand, and the force is the weight of the shoe. We can say that the weight, or the force, of the shoe is producing a torque at the shoulder. The torque in the shoulder is found by multiplying the length of the lever (the arm) and the force (the shoe’s weight). Therefore, we can decrease torque in the shoulder by either decreasing the weight of the shoe or decreasing the distance of the lever arm (amputation is never an option in physics problems).
Here's where some people get confused. The lever arm length is not determined by distance of the lever itself, but rather by the perpendicular distance from the point of force application to the center of rotation. Therefore, torque in the shoulder can be decreased simply by dropping the arm down a few inches. We can drop a straight line down from the shoulder, and then another straight line over to the new location of the shoe. The second straight line would be the new lever arm. So you can pretty much bring torque down to nothing at all by simply dropping the arm all the way down to the side. With the arm at the side holding the shoe, there is no rotational torque at all, just the weight of the shoe pulling straight down on the shoulder (technically, that's not rotational torque, just a downward force).
Now let's quickly assume the arm is back up completely straight at the side holding the shoe, and the shoe is producing a downward torque on the shoulder. There is one more source of torque: the torque needed to keep the arm up. That's right - it is produced by the muscle itself, or, in this case, the rotator cuff and deltoid muscles. By contracting, or shortening, they produce a torque at the shoulder joint that opposes the downward torque of the shoe.
Why is this important for triathletes? Because the amount of torque produced in a joint determines how much force the muscles must produce to resist that torque. By minimizing torque production at a joint in one direction, an endurance athlete can minimize fatigue, and by maximizing torque production at a joint in the opposite direction, an endurance athlete can maximize power and velocity. As you can see, this is crucial in pursuing the THG. Next week, I'm going to tell you exactly nine different ways you can either minimize the "bad" torque or maximize the "good" torque in the swim, the bike, and the run.
Until next time, train smart,
Ben Greenfield