body dynamics in yoga poses

(fall 2020)

WHAT IS IT?:

Yoga is known for its physical benefits including increased balance and flexibility. However, if poses are not executed correctly, it may lead to injury instead. One factor that affects stress on joints is stance width. While previous research has been done on stance width in other exercise fields, there is limited data regarding yoga. In order to quantify the effect of stance width on force distribution in yoga, the resulting force on the forward and backward limb was measured against varying stance distances in downward facing dog and warrior II.

I designed an experiment to measure postural stability and the force distribution ratio on the anterior and posterior limbs in different yoga poses.

This is an ongoing class, check back in for progress throughout the term!

ROLE:

I worked in this class as an individual researcher. I was responsible for the experimental design, experimental setup, data collection, data analysis, and report writing for the entire project.

Analysis Methods

I collected 25 trials for two poses of time series data of force on both limbs and angle of bend in LoggerPro, connected to FP and GNM sensors with LabQuest Mini. Then, in MATLAB, I averaged the force over time for each individual trial and found the fit for relation between stance width and force felt by each limb, and stance width and angle of bend in both poses. Then I calculated distribution ratio between force on forwards limb and backwards limb (Ffront/Fback) for each trial and plotted points and curve fitted to find relation of force distribution ratio to stance width.

To determine postural stability, in MATLAB, I calculated standard deviation for each trial and averaged the five trials for one stance width.

RESULTS:

The force distribution represented as a ratio of force felt by front foot to back boot shows nonlinear, logarithmic growth, consistent with observations of force felt by each limb alone in downward dog. The distribution ratio in warrior II appears linear, which is also expected from previous observations of the force behavior of each limb alone.

Standard deviation was used as a representation of postural stability. In both cases of downward dog and warrior II, as stance width increases, standard deviation decrease, then increases, following a parabolic fit for both poses. This indicates that there may be a “sweet spot”, where optimal postural stability occurs at a moderate distance in the medium range, not at the extremes.

SKILLS:

• experimental design

• research

• data analysis