Painful neck = weak breathing ∞
Intriguing: this test of 90 patients (half with neck pain, half without) showed that neck pain correlates pretty clearly with weak breathing. But is the weakness a cause? An effect? A bit of both, perhaps — if I had to guess (and I do have to guess), I’d guess “all of the above.” Both pain and weakness are probably both a cause of and an effect of the other.