Friday, February 4, 2011

Optimal Hiking Grade - A 50 Hike GPS Analysis

Do you care about optimal hiking grade? Maybe not, but it's interesting for us to think about.

Intuitively, some may think that steeper trails should get you up higher more quickly because less energy is being put into the "horizontal miles" that a less steep trail would need.

However, we probably also feel that at some point something becomes too steep to ascend without the looseness of the terrain affecting our pace.

So what's the "optimal" grade? Well, I'm sure the answer is unique to an individual, but let's look at one person.

We previously did a little exploration into how Vertical Ascent Rate (VAR) varied with the steepness of a trail, but only with one example. Now I've combined 50 hikes worth of data.

The hikes:

  • Mostly in southern California (especially San Gabriels), some in Sierra and Bay Area
  • Diverse in conditions, includes much on trail and off trail
  • Some have brush
  • Varied terrain (loose, bouldering, etc...)
But it's a set of "real" hikes that I've done. A little Matlab coding and analysis, and we can see how often a given grade of terrain was hiked:

Tuesday, January 18, 2011

Walking Mechanics Part 1: Center of Mass Control

Understanding mechanics provides the foundation for strong understanding of human movements (like hiking).

Why would you care about hiking mechanics? Well perhaps you have some questions about joint loading, energy expenditure, technique...and grasping basic principles may lead you to better understanding to answer such questions (and also realize that usually it is not as black and white as some may say).

For instance, why do we expend energy when walking on flat ground?

Short Take Home Message:

The need to keep angular momentum low (no rotating) constrains our choices in how we move.

Longer Explanation (Just go to "summary" if it's too long-winded)

Center of Mass
Now, biomechanics can have many levels of analysis, but we must start with the most basic, which would take us back to physics and representing the entire body as one point mass, called your Center of Mass (CM). We'll stick to 2D.