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Discipline: LD/Endurance, CMO, Trail Rider, Cartoonist, Writer, Co-Director/ Green Bean Endurance
Email: jackereynolds@yahoo.com


November 27, 2009

Re-inventing the Phebes: Part 1-Glycogen




I've continued reading my book by Tom Ivers. Read through it once, and now on my second round. My little epiphany of the day concerned horses that tie-up (exertional rhabdomyolysis). My gleaning from Ivers was this: Extremely lean and fit horses are more prone to tie-up. This thought goes against conformity of thought, doesn't fit mean healthy? Doesn't fit mean strong? Doesn't fit mean all positive things? The answer is---well, that depends. Here is a true/ false scenerio.

Fit horse = Lean, well muscled horse
(false)
A horse that is looking mean and lean with well-defined musculature may indeed be lean, he may look cut, with nice muscle definition. But there may be an underlying problem. Does he have a glycogen load to draw from. A horse that is losing weight as he becomes fitter is working under a deficit. Somewhere along the line you will exhaust those glycogen stores during training, and when you do, lactic acid will begin to build, and the horse will begin breaking down muscle cells (tie-up). This may be a full blown tie-up requiring veterinary care, or an insidious cumulative process where the muscle gets leaner, and harder, waiting for the unfortunate episode that would tip the horse into a tie-up. If you remember, when Phebes tied-up she was at peak fitness. I just could NOT understand what went wrong. She was a lean, mean, running machine. She had also lost her glycogen stores. Fifteen miles into her first LD ride she had run out of (glycogen) juice. Twenty five miles in my horse is in serious, life threatening trouble. For every one pound loss of weight during a competition, one half pound of that loss is stored glycogen. Are we replacing those losses before we ride again? It may take a three day lay off with some groceries to put the horse back up to optimal pre-training weight. If you've trained too long in a weight deficit, it may take a month to get that horse back to pre-training weight. A horse in training should begaining weight, not losing weight. Much of the weight lost during a training session will be back overnight as the horse rehydrates. So if you trained a hard 15 miles and the horse lost 15 pounds, tomorrow your horse will show a 7.5 weight loss (glycogen loss) and this is the weight you will need replinished before training hard again. Ivers theory on feeding was to really feed the groceries! However, high carbohydrates for endurance horses(based on other informational sources) is not optimal, and could prove down right harmful! Simple sugars notwithstanding, Phebes is a horse that really loses weight in training. Last winter she was so thin that she needed a blanket for the first time ever on some cold nights in the barn. She was already set up for a cataclysmic event, the stars needed only to align, and then tie-up. This winter we are going in with a very good body condition score of 7-8 obtained by a four week layoff. It will be interesting to see how well she is able to maintain this weight when we start working once again. Her maintenance feed is a low carb / high fat feed called Cool Command. On actual work days she is going to need a more energy dense performance feed given as an extra pre- and post-ride ration. Since I don't have a scale that I can walk her on all I'll have to gauge her next day weight loss with a weight tape, eyeball, and gut feeling. I will also have an eye out for "jello muscles" as a truly fit horse should have very soft, jiggly (think water, and globs of stored glycogen in each cell) muscles. Not lean, cut, toned, or hard muscles. Ivers book has really been an eye-opening experience for me. Things I did not understand before now make perfect sense.

Next time: Progressive Loading

~E.G.

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