One of the ways to do better in a race is to figure out a way to use less effort to produce the same or greater speed. In swimming this is obvious, and we spend a good deal of time trying to master the skills which allow us to go faster in the water while being limited by our own strength and/or endurance. On the bike and run it’s not quite so obvious, but we can make certain measurements that lead us in the right direction.
THE RIDER POSITION
On the bike I like to start with rider position or “bike fit.” There are many methods that can get you in the ball park range of a good fit but the best way to decide on a position is to measure performance directly. We start with current bike position on a Velotron by Computrainer (a computer controlled, precision electronic bicycle ergometer). I like this machine because it is so darn accurate and leads to accurate decisions.
We first measure heart rate and watts at race pace cruise until the heart rate stabilises for a given steady state watt output. This usually takes about 5 minutes and the watts target may be anywhere from 160 to 300 watts depending on the fitness of the rider. The rider should be in the position held for the most time during a race (which is down on the aero bars for us tri geeks).
Once we have a baseline heart rate and power output we can make changes to the rider position incrementally. I start with crank length and reduce it by 5mm and take another measurement of heart rate/watts keeping the watts the same in all measurements. Keep playing with the crank length until you get the lowest heart rate for the same watts output. Most riders find that they have better efficiency with a shorter crank than they are currently using.
Next we play with seat height then fore/aft position until we get the lowest heart rate. The major factors are crank length and seat position. The best handle bar position is a combination of power efficiency and aerodynamics so there is not an absolute right answer here. I will personally choose the most aero position that I can comfortably maintain for the distance of the race. The shorter the race, the more of an aero position you can usually maintain. One caution – it’s not a good idea to make big changes to bike position the day before a race!
THE BODY ITSELF
Once we have the bike position figured out we turn to the body itself. A healthcare provider that is certified in biomechanics can watch the rider and spot inefficiencies. Typically there is a relative weakness or functional problem with a muscle, ligament or joint that affects pedaling mechanics and makes some muscle work too hard. It is easiest to see the muscle that is working too hard but the real culprit is the one that isn’t working hard enough.
A common example of this is when there is a problem in the quadriceps usually from intensive and long training both on the bike and the run. When the quadriceps do not provide enough force to move the pedal down the rider will recruit more force from other muscles. Often the ones recruited are the adductors on the inside of the leg. Since the adductors are not on the same line as the quadriceps they will push the pedal down but in the process they will also pull the knee inside toward the top tube. This is the primary reason the knee deviates toward the top tube during the downstroke.
We now “fix” the one that is causing the problem. It isn’t the adductors that are pulling the knee in. It’s the quadriceps that are not working hard enough. One by one we fix the problems until there are none left or we run out of time. Another thing to note is that these changes can be made even on the day before the race.
We typically see a 5-15 beats per minute reduction in heart rate for the same watts output after going through this process. In actuality, the athlete will usually opt to raise the watts output during training and racing and end up with the original heart rate. I guess athletes would rather go faster than have an easier race. Go figure.