Training for the 1500/1650: Suggestions?

I have no clue what En1, 2 or 3 stand for, but, for me, I think a lot of work on longer distance sets (300 to 600) over 2K to 3K continuously with relatively little rest (e.g., 5 or so seconds per 100) on as fast an interval as you can hold is great for building endurance. I highly recommend Maglischo's "Swimming Fastest" for lots of great ideas for distance training (and other types too, of course). V brief summary here, but go to the source. Maglischo definitions: En-1 -- what he terms "basic endurance training" -- is somewhere between aerobic and anaerobic threshold. Anaerobic threshold is where LA production/removal are equal; aerobic threshold is described as "the minimum speed that will produce an improvement in the aerobic endurance of slow-twitch and some low-threshold FTa muscle fibers." Recommended set length are 2000 yd; rest intervals are fairly short (5-10 sec for short repeats; 10-20 for middle-distance; 20-60 sec for longer repeats). Maglischo recommends that distance swimmers spend a lot of time in En-1 "most of the endurance training that distance swimmers do should be in the basic endurance category (En-1)." En-2 is at anaerobic threshold ("threshold endurance training"). Example sets are 20-40 x 100 or 10-20 x 200 with approx 10 sec rest between repeats. Keep in mind the point is NOT to be at race pace; the point is to be at LT. He likes repeat distances of 200s or longer. Maglischo says "Distance swimmers can and should swim more of their repeats near threshold speeds (En-2) than other swimmers." He goes on to recommend 1-2 sets of En-2 per week in the early season, increasing these in the middle season, and then tapering off later in the season as more training is done in En-3. En-3 training is above LT and produces acidosis; Maglischo also calls this "overload endurance training." This would include most of what we have been calling "race pace" training...as long as the set lengths are fairly long and the rest intervals are not too generous. (For example, doing mile race-pace on a couple 50s with lots of rest is not very challenging and won't produce much acidosis.) En-3 set lengths are somewhere between 500 and 2000 yards. Rest intervals can be somewhat longer than En-1 or En-2 but still not real long. Example sets are 6-10 x 200 with 10-30 sec rest. But he also includes as an example 10-20 x 100 on the shortest possible sendoff. I believe the point is to be producing reasonably high lactate levels for a relatively long period of time, not necessarily always swimming right at race pace. Maglischo cautions about doing too many En-3 sets. In the early season there is little En-3: maybe some descending sets would dip into this area. In mid-season he calls for 1-2 per week, and 2 per week late in the season. This is all very general, and he gives lots of examples (I notice that Kieren Perkins and Janet Evans seemed to do a little more than two En-3 sets per week; more like 3-4 per week). But some key points for distance swimmers are: longer set distances and repeat lengths, not a lot of rest, and the fact that more time should be spend below LT than at or (especially) above it.

I have no clue what En1, 2 or 3 stand for, but, for me, I think a lot of work on longer distance sets (300 to 600) over 2K to 3K continuously with relatively little rest (e.g., 5 or so seconds per 100) on as fast an interval as you can hold is great for building endurance. I highly recommend Maglischo's "Swimming Fastest" for lots of great ideas for distance training (and other types too, of course). V brief summary here, but go to the source. Maglischo definitions: En-1 -- what he terms "basic endurance training" -- is somewhere between aerobic and anaerobic threshold. Anaerobic threshold is where LA production/removal are equal; aerobic threshold is described as "the minimum speed that will produce an improvement in the aerobic endurance of slow-twitch and some low-threshold FTa muscle fibers." Recommended set length are 2000 yd; rest intervals are fairly short (5-10 sec for short repeats; 10-20 for middle-distance; 20-60 sec for longer repeats). Maglischo recommends that distance swimmers spend a lot of time in En-1 "most of the endurance training that distance swimmers do should be in the basic endurance category (En-1)." En-2 is at anaerobic threshold ("threshold endurance training"). Example sets are 20-40 x 100 or 10-20 x 200 with approx 10 sec rest between repeats. Keep in mind the point is NOT to be at race pace; the point is to be at LT. He likes repeat distances of 200s or longer. Maglischo says "Distance swimmers can and should swim more of their repeats near threshold speeds (En-2) than other swimmers." He goes on to recommend 1-2 sets of En-2 per week in the early season, increasing these in the middle season, and then tapering off later in the season as more training is done in En-3. En-3 training is above LT and produces acidosis; Maglischo also calls this "overload endurance training." This would include most of what we have been calling "race pace" training...as long as the set lengths are fairly long and the rest intervals are not too generous. (For example, doing mile race-pace on a couple 50s with lots of rest is not very challenging and won't produce much acidosis.) En-3 set lengths are somewhere between 500 and 2000 yards. Rest intervals can be somewhat longer than En-1 or En-2 but still not real long. Example sets are 6-10 x 200 with 10-30 sec rest. But he also includes as an example 10-20 x 100 on the shortest possible sendoff. I believe the point is to be producing reasonably high lactate levels for a relatively long period of time, not necessarily always swimming right at race pace. Maglischo cautions about doing too many En-3 sets. In the early season there is little En-3: maybe some descending sets would dip into this area. In mid-season he calls for 1-2 per week, and 2 per week late in the season. This is all very general, and he gives lots of examples (I notice that Kieren Perkins and Janet Evans seemed to do a little more than two En-3 sets per week; more like 3-4 per week). But some key points for distance swimmers are: longer set distances and repeat lengths, not a lot of rest, and the fact that more time should be spend below LT than at or (especially) above it.