" 2 x 15-18 min. at LTV (no variation in pace during either run)/5-7 minutes easy jog between runs.
This workout is a slightly harder effort than either of the previous two LT workouts, especially if the maximum run length of 18 min. is used on both reps (2 x 15 min. is normally used by runners with less base mileage or less experience). No attempt should be made to pick up the pace at the end of either rep, although the entire second run can be done faster than the first if the first seems excessively easy. This workout allows more time spent at LTV than would be prudent to spend in any continuous effort (without the 5-7 min. rest) short of a time trial. The 5-7 min. recovery jog period gives the time to clear any accumulated lactate and lets the neuromuscular system relax briefly.
For 30:00 10K runner Dave, 2 runs of 3.5 miles each at a 5:02 pace provides the optimum effect directed toward improving his LTV. Each 3.5-mile segment would require about 17:38 at Dave's LTV.
This type of workout is also excellent for improving economy (owing to the overall time spent at LT pace), provided the pace remains even throughout both runs and never exceeds LTV. Going faster than LTV for 18 min. twice would probably become too strenuous to affect running economy.
It is usually a good policy to add 4-6 buildups during the post-workout cool-down period in order to recruit FT fibers. This ensures that FT fibers will be mobilized after ST ones are fatigued from the workout. The purpose is to influence correct sequential fiber recruitment, which is one of the most essential components of fast-paced running.
10-15 x 3 min. runs at LTV (first 1-2 reps slightly slower, last 2-3 gradually faster)/30-35 secs. rest periods between.
This workout provides 30-45 min. of running at LT speed, which would probably be too close to a time trial effort to maintain efficiency were it not for the rest periods. Notice how short the rest periods are in comparison to the run periods. This type of workout is sometimes referred to as being of high density. It is crucial to stay within the pace guidelines on high density sessions, since going too fast with very little rest would adversely affect relaxation and economy.
Dave, our college distance runner with PRs of 14:20 and 30:00, has a LT pace of 5:02 per mile. Dave would cover 950 meters in 2:58 at his LT pace (75 secs. per 400), so he could run the indicated workout on a track, then shuffle the remaining 50 meters to the next half-lap line before starting his next rep. This workout could also obviously be performed away from the track, either on a measured course or by effort. As usual, it's best to start slower and finish faster. So Dave could begin with 77 second 400s, warming up a little, and finish with 73 pace or even faster. The middle 2/3 of the reps should be done right at LT speed in order to promote efficiency.
Ronaldo DaCosta (2:06:05 marathoner) has reportedly run 15 x 1,000 meters at 3:00 each with 30 secs. rest periods. This is actually about 1 second per mile slower than his marathon pace! This is, however, just a workout (and no mention is made as to whether it was done at altitude). The moral is that relaxation and efficient rhythm are more important than "tying up like a big dog" when the objective of the workout is to train the aerobic component. If a former World Record holder runs his 3 min. repeats that slowly in comparison to his LT pace (which is probably about 4:35 mile pace), then going a little easier than possible can't be all that bad! Actually, DaCosta's 1,000s are run at about 95% of his predicted LTV, which is still within the zone which has an impact on raising his LT, and the high volume at this pace will certainly improve his economy.
16-20 x 400 at 105% of LTV (about 3-4 secs. per 400 faster than LTV)/20-25 secs. rest periods.
This workout gets to the upper limit of the training zone which works on raising the LT, and it actually approaches the speed which trains the VO2max. Its effect on LTV results mainly from the very short rest periods. The pace involved is a little faster than 10K pace for most runners, and people slower than 35:00 for 10,000 should tend toward 16 reps rather than 20 (some world-class runners do more than 20) at this pace.
Our hypothetical 30 min. 10K runner Dave, whose LTV is 5:02 mile pace (75 secs. per 400), runs at 71-72 secs. for his 400s on this workout. A few can be slower at first, some gradually faster at the end (as usual), but about 3/4 of the reps should stay at 71-72 to reinforce the rhythm.
Since the rests are so short, the heart rate will not decrease much (if any), but this is good by reason of the fact that lactate is used as a fuel by the heart as long as the rate of its accumulation does not increase sharply. If performed correctly, this workout produces a virtual steady state of cardiac output at a much faster pace than could be attained on a continuous run without going into the anaerobic zone. The heart rates during this workout generally stay above 85% of maximum effort but below 90%.
Ronaldo DaCosta's published workouts include up to 25 x 400 at a 66.2 average with 15-20 secs. recovery periods. Because of the higher number of reps and shorter rest periods, this should represent 103% of his LTV, and indicates that he could run at a 4:34-4:35 pace for an hour (about a half marathon). This is equivalent to "only" 2:07:30 for the marathon, but is consistent with DaCosta performing better as the distance increases. DaCosta also appears to work out a little below his utmost capabilities, possibly to work more on economy or possibly because of the cumulative loading effect of his two long runs per week. He also reputedly performs drills regularly and would presumably want to remain fresh enough to make them productive. In any event, there's a lesson in this inasmuch as workouts which are meant to train the aerobic system should not be run as hard as possible! "