Day 1: Jogging for Life

Day 1.

In many ways this is so true. I’ve let my practice down severely after a series of accidents and ill health. The big one was a motorcycle accident I had a few years ago after which I stopped practicing altogether. But today I feel better. I feel out of practice, but I also feel like I have turned a corner in my life. Finally — in many ways, not just physically and mentally but with my job, I finally can set aside all the worries of my daily life and concentrate on kunfu.

Why Kungfu and not Weiqi, or some other art or hobby? I’ll bring that up later (or not at all). But the focus on martial arts has multiple benefits for be besides fulfilling a lifelong ambition.

For now, here’s day 1. There will be more to come soon; I have three days worth of footage lined up for editing.

Stretch Machine Calculations

When I bought my splits machine, I had no way to easily calculate the angle of the machine. So I dialed in a visual 90° angle and started looking for convenient ways to measure the machine’s leg length. I measured a leg length of 28 to the screws at the end of the leg, and then measured the “base” of the triangle between the opposite leg’s screws. I discovered a measurement of 39.5, which gave 89.717°. Measuring from the absolute ends of the machine legs show a leg length of 29 and a base (spread distance) of 41, for a result of 89.996°. This was very accurate and since it was round numbers I was happy with the results.

I would then use an on-line triangle calculator to determine the angle of my splits for the session by measuring the distance between the legs.

Months later it occurred to me that I could just measure the distance between the legs and use that to index a previously calculated figure. So I re-measured 180cm from end to end at 180°, and then 125cm end to end for 90°. The implication being that the factor is about 1.6° per cm as you go from 125cm to 180cm. To test this I dialed in a visual 135° using the tiles on the floor and measured 164cm. This is an extra 39cm, and I expected only an additional 27cm. So the figure gets more accurate as you get closer to 180°. What would be better, likely then, is to do a table of expected results based on the leg length and not rely on a formula.

However while doing the table I kept coming back to highly accurate visual results indicating that a leg length of 29 (88cm) was very accurate between 90° to 180°. It became simply too convenient to use this number. Yet, when measuring at 180° we got 180cm, so perhaps using a leg length of 90cm would be a bit more accurate.

As it turned out, a leg length of 90cm provided greater than a very careful visual tuning of the angle. At 135° and 90°, observed error was attributable to human error. For example, I tried to make the machine 135° and measured a 165cm spread from pad-end to pad-end. This would give us 132.9°. But when I went to visually check the degree I found it to be slightly inside 135°. Meaning, closer to 132.9°. Thus the leg length of 90° was adopted and used to key spread lengths to spit angles.

Table 1: Spread Length to Angle

Spread Length Expected Angle
180cm 180°
175cm 153°
170cm 142°
165cm 133°
160cm 125°
155cm 119°
150cm 113°
145cm 107°
140cm 102°
135cm 97°
130cm 92°
125cm 88°

Table 2: Required Spread Length for Angle

Angle Spread Length
180cm 180cm
170° 179cm
160° 177cm
150° 174cm
140° 169cm
130° 163cm
120° 156cm
110° 147cm
100° 138cm
90° 127cm

More later.