Sweat testing flagged cramp-prone footballers and nobody else
Among 350 college athletes in eleven sports, sweat rate and sweat saltiness picked out cramp-prone American footballers only, and weakly: 0.65 to 0.72 where a coin toss is 0.5.
What the study found
One sport where sweat did pick out who cramps: American football
Inside the largest study to find nothing, one group separated. Among 350 college athletes across eleven sports, sweat rate and sweat electrolyte content identified cramp-prone American footballers and nobody in the other ten. The accuracy was weak: 0.65 to 0.72 where a coin toss is 0.5.
The caveat · Forearm patches, never mid-cramp
Weak discrimination is not a screening test, and the authors do not offer it as one. Cramp history was self-reported, and sweat was collected during ordinary training, never during a cramp. Forearm patches estimate whole-body sweat sodium indirectly and carry real measurement error. One other significant result among roughly fourteen comparisons, potassium content in women, is what chance produces at that many tests.
What we don't know
Weak discrimination is not a screening test, and the authors do not offer it as one. Cramp history was self-reported, and sweat was collected during ordinary training, never during a cramp. Forearm patches estimate whole-body sweat sodium indirectly and carry real measurement error. One other significant result among roughly fourteen comparisons, potassium content in women, is what chance produces at that many tests.