wi_voter

wi_voter t1_j2n99bw wrote

Reply to comment by eliseannette in Researchers have discovered a new situation from the everyday environment where our crucial ability to perceive what is truly vertical is compromised: when our body pitches (body pitch) and moves at the same time (body motion) by giuliomagnifico

Your pelvis, relatively the center of mass, moving backwards and lower really balances you on the slopes. The leaning forward with the upper body is already coming from a posterior position.

I love watching skiers especially on moguls. I used to ski myself until I moved to Wisconsin. The little bunny hills aren't worth the lift line.

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wi_voter t1_j2n3ub3 wrote

Reply to comment by eliseannette in Researchers have discovered a new situation from the everyday environment where our crucial ability to perceive what is truly vertical is compromised: when our body pitches (body pitch) and moves at the same time (body motion) by giuliomagnifico

I think this study was dependent on people reclining back as they are going up the incline. Without head support I wonder how many people stay completely reclined or "pitched" backwards. There is a natural reaction to want to right your head unless supported.

Skiing is interesting because it is actually the opposite. There is a decline while you are leaning forward with your upper body. However, with that lean forward you are still lined up over your base of support because of the flexion in your legs. In the experiment the upper body is out of that alignment over the lower body.

It would be interesting to have them use the vertical pole with skiers and see what the results are. I am guessing they would still be accurate but who knows.

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wi_voter t1_j2mps3u wrote

Reply to Researchers have discovered a new situation from the everyday environment where our crucial ability to perceive what is truly vertical is compromised: when our body pitches (body pitch) and moves at the same time (body motion) by giuliomagnifico

I am intrigued by this study so back to comment again. I would think being able to position something vertically is related to our sense of gravity. Gravity is the one constant we all have in our sensorimotor development so it is interesting to find a set of circumstances where it is skewed. Also, noted that in the dental chair the head is supported while on the tram it is not. Wonder if that makes a difference.

My thoughts on where this is applicable is with children with significant motor development who are in wheelchairs, often reclined and are then pushed by others. Or those that can use a power chair but are in slightly reclined position. They may be better off if they can tolerate a more upright position (maybe a new health insurance justification for more therapy). They would be in this circumstance longer than someone on a tram, usually a whole school day once they are school age. I wonder if there is a lasting impact on their relationship/experience of gravity and the vertical.

Anyway, just some thoughts I had. Thanks for posting the study.

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wi_voter t1_j2lfks6 wrote

Reply to comment by _tropical_tundra_ in Researchers have discovered a new situation from the everyday environment where our crucial ability to perceive what is truly vertical is compromised: when our body pitches (body pitch) and moves at the same time (body motion) by giuliomagnifico

I added this edit if you didn't see it:

rereading it I believe by body pitch they mean the extent the person is leaning backwards so their head/upper body is posterior to the vertical axis. That would make sense since they used the dental chair to create "pitch" without movement.

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wi_voter t1_j2ldui7 wrote

Reply to comment by _tropical_tundra_ in Researchers have discovered a new situation from the everyday environment where our crucial ability to perceive what is truly vertical is compromised: when our body pitches (body pitch) and moves at the same time (body motion) by giuliomagnifico

We simply refer to it as LOB, loss of balance and the attempt to regain midline either balance or equilibrium reaction. I can see how the term pitch could fit the action of being displaced.

In this study it doesn't seem like a sudden unexpected change in displacement but a response to the incline which we'd usually call a righting reaction, assuming that is what they mean by pitch in the study. Trying to confirm so I know I'm understanding it correctly.

edit: rereading it I believe by body pitch they mean the extent the person is leaning backwards so their head/upper body is posterior to the vertical axis. That would make sense since they used the dental chair to create "pitch" without movement.

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wi_voter t1_iwrz4uv wrote

Reply to I saw in a video that chimpanzees and gorillas do not knuckle-walk in the same way, but they didn't explain what the difference is. Could someone elaborate on the physiological/anatomical differences? by [deleted]

I have to jump in with an FYI. The reason humans do not have to knuckle walk is because our pelvic bones are oriented more in the frontal plane while other primates have their pelvic bones oriented more in the sagittal plane. Our frontal plane orientation allows us to successfully stand on one foot when the hip abductor muscles contract on one side and keep the pelvis from falling on the other side like a seesaw.

Jumping in because years ago in college I got to assist in the research on the hip abductor muscles and their role in unilateral stance and gait. This was always one of my favorite little factoids from those days. :)

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