it's certainly contradictory to anything else i've ever seen about coffee, given that it's a diuretic. but it may still be a matter of degree and combinations.
this study looks at 6 cups a day combined with rather than instead of water
Coffee Consumption and Total Body Water Homeostasis as Measured by Fluid Balance and Bioelectrical Impedance Analysishttp://www.karger.com/Article/Abstract/177975
During the first day, fluid requirement was met by mineral water. On the following day the same amount of fluid was supplied and the mineral water was in part replaced by 6 cups of coffee containing 642 mg of caffeine. This led to an increase in 24-hour urine excretion of 753 ± 532 ml (p < 0.001), a corresponding negative fluid balance and a concomitant decrease in body weight of 0.7 ± 0.4 kg (p < 0.001).
bringing it back to spasticity in particular, here's an odd study:
A double-blind, randomized, crossover study of the safety and efficacy of a combination of carisoprodol, paracetamol, caffeine, and B-vitamins in the treatment of spastic muscle contractureshttp://www.moreirajr.com.br/revistas.as ... teria=3592
"oral administration of the combination of carisoprodol, paracetamol, caffeine and the B-vitamins is safe and effective in the treatment of spastic muscle contracture."