A common question when it comes to training is, “what type of training is best for me?” And while you could argue that your body will adapt to any type of training, the truth is, the answer might depend on your muscles genetic makeup.
Before we get too deep, lets back up so we’re on the same page. First, all muscles have the same anatomy and go through the same sequence of receiving a signal resulting in a contraction. But all of our muscles are comprised of Type I and Type II fibers. These muscle fibers are your “slow twitch” Type I fibers and “Fast Twitch” Type II fibers. In rowing terms think 500m and 10,000m events, you know which end of the spectrum you tend to enjoy so from this point it’s really about how you train those muscles to get better at that duration.
This makes sense because our Type I fibers are more fatigue resistant where our Type II fibers are more powerful. Back in the day, we use to walk long distances. For instance, Roman soldiers had to march about 30 kilometers in a day (not many of us walk on our hands for long distances). So our lower body was designed to fight fatigue while our upper body was designed to be more forceful and powerful.
So what makes Type I fibers slow twitch and Type II fibers fast twitch? It all goes back to what we just talked about above.
We’ve all heard the phrase, “bigger, faster, stronger”. Well, the same rings true for our muscle fibers. Type II alpha-motor neurons and muscle fibers are bigger, faster, and stronger than Type I fibers. Type II fibers also break down ATP faster, which increases the cycling rate of contraction. Lastly, calcium is released from the sarcoplasmic reticulum faster in Type II fibers, which coupled with the faster ATP breakdown, makes the contraction even faster.
Type II fibers dominate physiologically for strength and power whereas our Type I fiber produce less force, are more fatigue resistant and have more stamina.
So, what does Type I and Type II fiber recruitment mean for us as rowers? This is where we run into what exercise scientists call the “Size Principle” and “Principle of Orderly Recruitment”.
The Size Principle tells us that motor units are recruited from smallest to largest. Since we know that Type II fibers are bigger, faster, and stronger, we can conclude that Type I fibers will be activated first, followed by Type II fibers. So, there is an order to fiber type recruitment.
We can further classify our motor units into “low threshold” and “high threshold” categories. Motor units for Type I fibers are classified as “low threshold” motor units meaning they have a lower activation threshold making it easier for them to fire. All the while, motor units for Type II fibers can be further classified as “high threshold” motor units as they have a higher activation threshold that must be reached in order for them to activate.
Let’s look at an example putting together the concepts of the Size Principle and Principle of Orderly Recruitment with low and high activation thresholds.
It would not be very efficient of your body to use your big and strong Type II fibers to pick-up our cell phones. Cell phones are light and require little amounts of force, so your lower threshold Type I fibers will be activated. However, if you are trying to deadlift 500 pounds (which takes a lot of force), your body will first start to recruit your Type I fibers and quickly realize that you need to use your big, high force output, Type II fibers.
Type I = Fatigue Resistant
Type II = More Forceful Contractions
So in summary, ‘what type of training will suit me best?’ it’s a little bit of science and a little bit of what you enjoy. There is no right or wrong answer but you’re always going to find a distance that you prefer and your training should either support that or purposely compensate for the weaknesses you have in order to elevate your lowest level of training and fill in any physiological gaps that may exist. Too many people shy away from their weak points and favor their strong points but the most successful people in this world are the ones who place themselves in positions of failure in order to learn from the experience and develop into stronger humans.