Muscle mass and protection from injuries

Does increased overall muscle mass give protection from physical injuries, notably car crashes? Would you have a bigger chance of surviving a crash if you are muscular as opposed to average or skinny? Would the advantage be significant or negligible? I figure that increased body fat instead of muscles may have comparable effect, but may be counterproductive because of other health risks associated with it, but how about a morbidly obese person in a crash?

Most safety features of cars are designed to the specs of the erstwhile average person of more or less crash test dummy proportions. Even so, the features still accommodate larger people, but as you get into the obese and especially morbidly obese categories, not as much. Seatbelts, for example are more difficult to place properly (around the waist instead of the abdomen) and the improper placement may result in injuries. But it seems your question has to do with a possible protective effect of the increased padding, independent of these other factors. Tha t I don’t know about but it seems like a reasonable hypothesis.

Hmmm…based on my experience (25 years or so as an ED physician), I’d say more muscular individuals are basically more resistant to most blunt force injuries, including most of the kinds of injury from a car crash.

They have stronger bones, ligaments and joints. They have more “padding” from the muscle mass. They have stronger chests and abdominal walls…so on.

But they also have more mass, so in some situations, I can imagine that a lightweight person or a child might benefit from the diminished force associated with a lower mass, given the same deceleration. Most car crashes are not quite so pure, though.

I guess I’d say it’s been my experience (hundreds; maybe over a thousand? car crashes) that fragile people, who tend to be lighter and skinnier (think little old grandma) break easier. I’ve seen an adult individual with a double break of an arm just from an airbag (and of course, these can kill children), for example, and I don’t think that would happen with Mr Universe.

I think the difference is significant, but it’s a bit hard to quantify.

If you’re just fat, I think you’d get more auto air bag from the fat, but also more decelerative force without the concomitant value of strong musculoskeletal construction. So…fat guys=worse injury, I’d say. (Plus, missed injuries, if you are really fat.)

Very good answer. Gotta work out like a madman.:slight_smile:

I agree with Chief Pedant. Weightlifters, athletes, cement workers, construction workers, etc, build more muscle mass than a more sedentary person. The activity that increases muscle mass also makes bones stronger and thicker. Joints would be better protected and less likely to become separated or inured by the force of a collision. Muscle mass probably won’t provide much protection against foreign object penetrations (ie tree branches, metal rods, sign posts).

Ignoring passenger restraints for a moment, the impact difference between a 170lb person and a 200lb person traveling 20 mph would be greater for the heavier person. Assuming both had been an average body-type of 170lbs and one had added 30lbs of muscle and thicker, stonger, heavier bones, the 200 pounder would be in a better position to survive the impact. It’s not likely that either would be able to survive a 40 mph impact.

An outright bodybuilder might take more harm under some circumstances due to being musclebound and not flexing as much with the impact.

  1. The muscle bound inflexible body builder is a bit of a myth.

  2. Less flex is preferred in trauma. That resistance protects the tendons and ligaments and even the bones.

I agree with this, however (and this could just be ‘bro science’, so beware), I was thinking about something. I’ve often heard that, when in an accident, a drunk person is less likely to damage themselves because they are completely loose and relaxed, whereas the non drunk person tenses themselves in preparation for the accident. If this is true (which it might not be), then wouldn’t it stand to reason that someone with lots of muscle would be more tense and as a result would suffer greater damage?

What is flex? What allows flex? What is the limit to flex? I think in this situation the thing that is limiting flex is the tendons and ligaments and bones themselves. Thus, the crucial factor is how sturdy those materials are. Doesn’t matter if they start stretching at 45 deg or 85 deg, if the joint is bent 130 deg, you’ve surpassed the limit, and the material strength is the deciding factor. Conversely, if the loose person starts stretching at 85 deg but you’ve only bent 65 deg, the loose person is not in distress while the stiff person is.

Consider this factoid: female athletes in the sam sports as males (soccer and basketball being most studied) have 7 times greater incidence of ACL tears.

Sure some of that is sociocultural - in our society at least females tend to be more about the team and seem to be more likely to play injured. But some of it is that males are more heavily muscled and less flexible. You want the muscles to have limited the magnitude of flexion during trauma. When you get to the tendons and the ligaments absorbing the force and being the flexion limiter that is when something snaps.