Friday, October 24, 2014

Dispatch from Data Land: Doing Science

How to get a paleoanthropology/kinesiology research project off the ground (based on the last 6 months of this grad student's life):

1) Submit your proposal to the Institutional Review Board. Convince them that the carcinogenic exposure equivalent to less than 2 cigarettes is an acceptable level of risk for your subjects. Also convince them that evolutionary questions are worth asking--which is a question that would never occur to any natural scientist.... or resident of a secular first-world nation.*
2) Harass friends and harangue strangers (or is it vice versa?) into taking part in your study.
3) Work with super awesome, yet very busy, people at a cooperating institution.  Hope you're not asking too much with your constant barrage of emailed questions and requests. 
4) Feel like an imposter who knows approximately nothing about bio-anthropology and/or kinesiology.
5) Feel very indebted to everyone who takes nearly a full day out of their lives to travel around the state to get their foot scanned in a computed-tomography machine in Worcester and have plastic markers stuck to their hairy skin while they run down a runway in a basement laboratory in Amherst.
6) Analyze the data via a remote connection.  Watch the results trickle in and wonder if the next data point will demonstrate something interesting.
7) Miss an ambitious abstract submission deadline because people and machines are unpredictable.  Aim for another deadline.
8) TA Anthro courses/teach them online/teach biology at a high school.  Run your ass off.  Wonder why you don't have more time to work on your research.

*Social scientists on your review board will probably acquiesce, but those that surround you in academia will produce more consternation.  Many implicitly reject the biological basis of humanity. Approach them like you would an evangelical-- for it matters little whether their every thought is influenced by religion or another all-consuming belief.

Finally the exciting part!  With 2/3 of my data collected for this research project, it has become apparent that this will be a study of trabeculae-- fingerlings of bone that form with spaces between. This produces a light bone structure with excellent strength and shock-absorbing properties. The calcaneus is almost entirely trabecular bone.

human calcaneus from our lab, with a hole in the cortical bone exposing the trabecular structure.

Some aspects of trabecular strcture are greatly influenced by loading (from exercise, etc.) I'm thrilled to find that several trabecular measures differ between forefoot and rearfoot runners.  At press time, my sample sizes are small, and only one measure is statistically significant: trabecular thickness.

avg. thickness of trabeculae. not enough data yet on nonrunners to include in the analysis.

From the other data we collected on the posterior calcaneus, it seems that forefoot runners not only have thicker trabeculae, but less of them than rearfoot runners.  At present, there is no statistical difference in the overall density of trabecular bone.  Instead, the differences between forefoot and rearfoot runners can be chalked up to the thickness and number.  Prior studies suggest that bone responds to strain by thickening the trabeculae, not so much by making more; so does this mean that forefoot runners are showing more bone adaptation than rearfoot runners? This runs counter to what we may expect.  Rearfoot runners generate huge impact forces by landing on the calcaneus.  But forefoot runners generate greater achilles tendon forces, and since the achilles attaches near the region that we've sampled, we could be seeing the result of these forces.  

While not yet statistically significant, we're also seeing that the trabeculae of rearfoot runners are slightly more organized (lined up in the same direction), implying greater adaptation to strain.  However, some research suggests that trabecular orientation is set early in life, and doesn't change much based on strain or cessation of strain.  If true, then we're actually seeing the result of the strain environment my subjects experienced early in life, not the result of strains from more recent endurance running. 

Many cups of coffee or glasses of beer will be consumed in the quest to figure this stuff out. And more data still to come, including separate analyses of trabeculae in the 1st and 5th metatarsal bones.  But it's proving interesting and it will be new to science.  Hooray!

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