Let’s talk about enzymes! I love enzymes!
Enzymes speed up chemical reactions. What that means is that they make you run faster (although I skipped over a lot of steps!). In the absence of enzymes, chemical reactions wouldn’t occur quickly enough to generate the energy you need to run.
Enzymes have funny names, like succinate dehydrogenase and phosphofructokinase. Some of them are tongue twisters!
Enzymes can be activated or inhibited, which means that their effectiveness in speeding up chemical reactions can be either increased or decreased, determining which metabolic pathways are functional during certain cellular conditions. Enzymes essentially control metabolism and therefore control the pace at which you fatigue. Isn’t that cool?
Both aerobic and anaerobic training increase their respective enzyme activity. Do more aerobic training and you increase enzymes involved in aerobic metabolism. Do more anaerobic training and you increase enzymes involved in anaerobic metabolism.
Now listen closely because this is what you came for: The more aerobic enzymes you have, the more you steer metabolism toward a greater reliance on aerobic metabolism at a given pace. Without a surplus of aerobic enzymes, your muscles will rely on anaerobic metabolism and you’ll fatigue (slow down) at a slower pace. To be a better distance runner, one of the goals of your training should be to make as many aerobic enzymes as possible.