Gait:

• Gait Analysis for racing -- an interesting series of videoclips showing the benefits of slow motion video in appraising running horses.
• Study: Farrier Selection Impacts More Than Hoof Shape, by Christa Lesté-Lasserre, from The Horse, March 21, 2008 found that of 15 parameters studies, 14 differed significantly among six farriers over a one-year period.  Many of those parameters directly impact soundness.

Muscles and Structure:

Muscles -- their parts and their mechanism, that is, how they contract and relax.  This is an animated slide show that lets you test your learnings as it proceeds.

• Cellular Potassium / Sodium pump.  An animated description of how these ions migrate across cell membranes.
• The Onset of Rigor Mortis in Various Muscles of the Draught Horse, by R. A. Lawrie, from the Journal of Physiology, Aug 28, 1953.  How ATP and ADP interact with Rigor.
• Maintaining Hydration and Electrolyte Balance in the Performance Horse, by Gayle Ecker, includes data from 100-mile horses running in 2001 and their "performance profiles."
• Weight carrying ability abstract
• Importance of glucose during exercise abstract
• Bone density not impacted in endurance sports more than pasture play abstract

Electrolytes:

• Electrolyte Supplementation for Endurance Horses: Effects on Fluid Losses and Performance, by F Sampieri, H Schott II, K Hinchcliff, R Geor, and E José-Cunilleras, in AAEP Proceedings, Vol 53, 2007.

Nutrition (including ulcers):

• Nutritional Management of Endurance Horses, by R J Geor, from the 9th Congress on Equine Medicine and Surgery in Geneva.
• New ulcer test based on fecal samples from The Horse
• Alfafa and ulcers (not what you might think) from The Horse
• How consumption rate of concentrates impacts glycemic index
• Links from toxic food sources to hind limb knuckling

Disease and Medicine:

• Study Links New Risk Factors to EPM Infection, by Stacey Oke, from The Horse.

How it works together / physiology:

• 10 Principles of Exercise Physiology, by Samantha Steelman, from The Horse June 2008 .