Wednesday, May 29, 2013

VO2max and running mileage

If you’ve been training for a while, chances are that your VO2max has plateaued.  VO2max is a pretty stable parameter, with further improvements in performance resulting from improvements in other physiological variables like lactate threshold and running economy.  While the exact volume of training at which VO2max plateaus is individual, a number of researchers have suggested that it plateaus at about 70 miles per week.  Any training above this won’t likely improve VO2max unless you include more intensity.

Thursday, May 16, 2013

Update on Mavic Crossmax SLR wheelset

It's been a year and a half riding on the Crossmax SLR Tubeless wheelset and I thought an update would be in order. How did they hold up? Absolutely perfect to sum it up. Their still true which is kind of amazing, no issues with the tubeless system, no flats. In the wet the Schwalbe Racing Ralph tires are like ice skates, while in the dry their grip is good. Bi-polar tires. The benefit of the tubeless is the lower air pressures I can run in the wet to offset some of the slickness of the Schwalbes. I never had any problems at low air pressures with the tires or rims burping air as Mavic set the UST standard for the bead locking design. There's no internal rim tape as the spokes do not protrude into the rim meaning its one less thing to worry about and knocking off a few more grams of weight. In the wet I run pressures in the low to mid 20"s psi. Dry conditions I generally run 26 to 29 which gives me good grip and softens the impact of a hardtail. These wheels lowered the weight of my wheelset by over a pound and their stiff like most Mavic wheels. All in all they make me feel like a better rider than I really am.

Saturday, May 11, 2013

Cardiac Drift

What is Cardiovascular Drift? If you've ever trained with a heart rate monitor you might have noticed that your heart rate increases as the workout progresses even though your speed and effort remain the same. What you’re experiencing is Cardiac drift. It's really a normal occurrence and can increase your heart rate up to 20 beats per minutes over a 30 minute period. You'll find it's more evident during hotter conditions and there are a few reasons that contribute to this. First, dehydration causes a lowering of blood plasma or volume forcing the heart to work harder to support working muscles and cool the body simultaneously. Correspondingly, the stroke volume of the heart decreases so that cardiac output and oxygen uptake remain the same, keeping your breathing and effort similar while heart rate elevates.  Acclimating to the heat and humidity can help diminish Cardiac drift but it will still occur to some extent.  It's important to remember low body fluids can still occur in cooler conditions so this is not a heat only occurrence. Hydration is a double edged sword against cardiovascular drift.  It fights the increase in core body temperature and it maintains blood volume.

Another contributing issue is muscular fatigue. During extended training when slow twitch muscle fibers fatigue (endurance fibers) your body attempts to compensate by recruiting additional muscle types. These muscles are generally fast twitch fibers which possess more brute strength but generate more lactic acid which in turn can elevate heart rate. This process is kind of a built in survival mechanism in the human body.

Lastly relax, anxiety, stress and tension can be contributing factors.