As stated in week three, your weekly long run increases aerobic base or stamina. Long runs improve your: aerobic pathways at the cellular level, stimulate more and larger mitochondria, more red blood cells, increase your blood volume and Myoglobin. Builds bigger heart, breathing and running muscle cells increases the quantity of blood pumped out with each heart contraction. The net result is an enhanced capacity to take in and distribute oxygen. This increased aerobic ability is technically called an increased maximum oxygen uptake capacity--VO2 max.
VO2 max, or Maximum Oxygen Uptake Capacity, to use its formal name, is the amount of oxygen we can absorb into our cells in one minute while working at full capacity. British coach, Frank Horwill, says that: “The best way to improve VO2 max is to run between 80 and 100 percent of VO2 max. One hundred percent equals the runner’s 3K or two mile race pace; 95 % equals 5K speed; 90 % is 10K running speed. “Work physiologists believe training at 95 % VO2 max brings the best results--though one Russian physiologist of note--Karibosk, thinks 100 % (3K or two mile pace) is better because it tunes up the anaerobic pathway.”
Once in a blue moon, so twice in 1999, logic meets science. Running a bit faster than 10K pace is obviously a good training idea because it prepares you for race pace. Running a bit slower than 2 mile pace intensity is easier on your body, which decreases injury and burnout risk (the full results of interval running take 12 or more weeks). Running at 5K pace, at 95 percent of VO2 max is recommended by most exercise physiologists, and it makes the most sense...in phase 4 of 10K running.
Interval running is simple but progressive: You run moderately fast for a tolerable duration: then you take a rest. You vary your rest period and hence you vary the stimulation to your body. Over the course of many running sessions you improve your VO2 max and you running economy. It is this modest stimulation to your body from running 1 to 2 minutes at 5K pace which stimulates additional improvements in your VO2 max and your running efficiency. Blasting a few reps faster than 2 mile pace will not help your VO2 max. Experienced runners: restrain yourself to 2 mile race pace if you’ve done lots of races recently. Running at 5K pace is better for most runners. Don’t let exuberance and training partners make you run faster than is good for you.
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