If there is a core principle at the heart of every morsel of health and lifestyle advice that we give away here at VP it could well be this: If you want your dog to live a long and happy life, you must minimize the amount of excess fat in her body. (We’ve expanded on that general principle here.)

This is a deceptively powerful little admonishment.  It draws on several well-developed strands of scientific evidence, all of which suggest that excess body fat will decrease your dog’s quality of life, expose her to all manner of dangerous diseases, and increase her risk of premature death.

But take a second and think not about what this important principle is saying, but what it’s not saying. Specifically, note that the core of our fitness and lifestyle philosophy has nothing to do with losing, dropping, maintaining, or managing body weight. Read More

Speaking generally, your skeletal muscle fibers fall into two broad categories, Type I  and Type II.  Type I fibers commonly are called “slow-twitch,” Type II fibers usually are referred to as “fast-twitch,” and the colloquial monikers are pretty appropriate: the maximum contraction velocity of a slow-twitch fiber is significantly slower than that of a fast-twitch fiber, although both produce about the same amount of force per contraction.  Relying primarily on aerobic metabolism to fire, slow-twitch fibers use oxygen more efficiently than fast-twitch fibers, which depend heavily upon anaerobic metabolism.  Accordingly, fast-twitch fibers are better at generating short bursts of strength or speed while slow-twitch fibers are optimized for continuous contractions repeated over a long period of time.

While all humans possess some combination of slow-twitch and fast-twitch fibers, those primed for long distance endurance activities, such as marathon running and stage-race cycling, possess greater proportions of slow-twitch fibers.  Athletes that excel at fast, high-intensity activities such as sprinting and weight-lifting generally possess greater proportions of fast-twitch fibers.  While I am unaware of any studies linking relative fiber concentration to other genetic factors, several studies suggest that training can be used to transform fibers from one type to the other.

Though they are also capable of being classified using even more specific terms, canine skeletal muscles generally fall into the same fast-twitch/slow-twitch categories as human muscles. Read More