Someone smart did a deep dive on the choking study and it's even worse than I thought
The value is half as elevated as you can get from swimming, is also correlated with depression a and anxiety and they didn't even properly attempt to control
I got a copy of that choking study going around. There are various issues - observational study, light sprinkling of p-hacking, poorly matched groups - but the biggest issue is effect size. Their primary finding is a statistically significant difference in the level of a biomarker called S100B (they tested 5 and got 1 hit). Women who reported being choked ≥ 4x in the last month had higher levels than women who reported never having been choked.
Setting aside the other issues and assuming a causal relationship, we should ask two questions here: what does S100B mean, and is the difference an amount that anyone should care about?
S100B is a marker that's elevated in people with acute TBI, hemmorhage, and other brain injuries. But it's also elevated when non-brain-related bones are broken, by melanoma, after surgery, and in depressed and bipolar patients. And by swimming, running marathons, or just having a high BMI. Baseline healthy levels are between 30 and 100pg/ml. The study doesn't actually provide numbers (which seems like a bad sign!), but we can eyeball the charts.
That gives medians of 44.7pg/ml vs 27.1 for the choking and non-choking groups respectively. Values for acute brain injury can be in the thousands, migraine, depression, bipolar, marathon running, and swimming, can get you into the hundreds.
So the difference is pretty small, and in a causal world who knows if it matters. The marker just isn't very specific. We can also tell a lot of stories about non-causal worlds that are consistent with the finding.
This choking group was more depressed (PHQ-9 score), more anxious (GAD-7), and drank more alcohol (AUDIT). They recorded these numbers, but used only the alcohol values in their initial 5-way statistical test, and used none of them in the subsequent univariate tests. Seems sus! But anyway, we already know that depression and anxiety are correlated with S100B. We can also easily imagine that women who like to be choked are more physically active. They could simply be more likely to have worked out recently. Or for that matter they could have higher BMIs and skew results that way. You can come up with lots of explanations.
My smart-layperson-with-access-to-the-internet-and-some-LLMs opinion is that I don't think this study really tells you anything. Which is not the same thing as saying choking is totally safe! I'm sure it's not risk free, but (mostly on intuition) it's probably not especially dangerous compared to other things you might be doing.