LSD (Long Slow Distance)

This post is for the newbie out there that hasn't got into the sport, but may be giving winter contemplation to doing so.  I know I have asked the question, what is Long Slow Distance (LSD), and what does slow mean?  The answer in some respects is simple, at least in the early weeks of conditioning a horse.  You can take the long, and the slow, and the distance at face value.  Riding the horse slowly (walking, a little trotting), increasing the length of time you are out there, and thereby inching up your distance.  Simple.  Right?  In the beginning, yes, it is.  But after an initial legging up process of say 30 days, and having worked a horse up to 10 miles or more, what then?   At some point you are going to peak at a certain distance.  Your horse in a sense has been there done that, and to keep doing it as you did may keep the status quo, but your horse will make no further cardiovascular gains, will no longer be further strengthening tendon, or bone.  It is at this point that LSD becomes something slightly different.  Now the horse may begin training aerobically at heart-rates close to, but less than 150 bpm.  What this means to you is that you will be phasing out walking and gradually phasing in trotting, and building the time that the horse is able to trot.  The first day you may only trot ten minutes at a stretch, next time maybe fifteen, slowly pushing out the horse's ability to maintain a trotting gait.  Eventually working towards a warm up, an hour long trotting session, and a cool down.  It may take a number of weeks to get there, and the trot may only average 5 mph.  Eventually the horse will master trotting the 5 miles in an hour and you can start stretching distance again, only you will be doing it at a consistent trotting pace compared to when you started and it involved walking and trotting.  I struggled for a long time getting the drift of what slow meant.  Fact is, it means different things when you start, than it will after you've done it for awhile.  It will mean different things to different riders based on their eventual ride goals.  But in the beginning, remember that slow does indeed mean S-L-O-W.