Let’s start with the basics behind these shocking statements: there are slow and fast twitch muscles, or type I and type II. The first major difference between these muscle types is the way energy, in the form of ATP, is used. Type I fibers are rich in mitochondria for aerobic metabolism, making them look red due to the increased oxygen and blood flow. This pathway helps you recover from repetitive explosive efforts like a soccer match. However, pursuing this energy system through long, prolonged exercise (i.e. over 60 seconds) will negatively affect your entire sport’s pursuit from a catabolic hormone profile to overuse injuries (see Sparta Point 12/31/08). Type II fibers appear white, and have larger diameters with higher amounts of phosphocreatine for anaerobic metabolism, pathways dedicated to providing energy QUICKLY.
The second major difference of fiber type is the rate of relaxation, which allows joint movement to continue to be accelerated (see Sparta Point 10/8/09). Type II fibers have a faster muscle relaxation rate for greater joint speed.
Then there are different types of type II muscles, particularly IIa and IIx. This type IIa is more similar to slow twitch fibers, rich in mitochondria, thus appearing redder. The type IIx fibers are the fastest muscle type due to their higher contractile speeds and greater force.
Any muscle damage and breakdown, like soreness, can shift fibers more towards the type IIa characteristics. Even movements like sprinting can cause this shift from extremely fast fibers to the more moderate compromise of type IIa. In fact, untrained people have more type IIx fibers than anyone as they do not require any endurance!
This information is not more ammunition to be lazy as more type IIx fibers won’t guarantee more GRF, which is the end goal for every athlete. Rather, the take home point is simple; ANY EXERCISE IS NOT ALWAYS BETTER. As a competitive athlete, you do not have the luxury of being accepting of all things, so here are a few guidelines.
1. Outside your sport’s skills, aggressively focus on anaerobic athletic exercise, like sprinting, jumping, or weightlifting, for about 360 minutes a week (we use 4 days at 90 minutes)
2. Channel your extra time into sleeping more, the average requirements are 9 ½ hours before you hit sleep debt (see Sparta Point 3/17/10).
3. Long distance running or exercise of any kind will make you fatter and slower, blame your nutrition for any positive or negative effects on your appearance (see Sparta Point 12/16/09).
Like everything, you need to decide your priorities first, and sleeping in or cooking instead of going for that hike may be the best training decision you’ve ever made.
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