I don't think there is a generally accepted estimate of the degree of strength of Neandertals. They are believed to have been of greater strength than humans on the basis of studying the relative size of their joints, their bone size and density, and the muscle connection origins in their bones.
Given those diferences with measurements of as much as 100% greater than an average modern humans, it is generally agreed that they were very strong people. But they probably were not, say, >2x as strong as a normal healthy man today, except perhaps in finger strength.
In fact, they had nutritional deficiencies, frequent injuries and arthritis, so their effective strength may have been greater than ours but they had their problems.
But I believe that as a practical matter, the average young Neandertal woman would be physically dangerous to a modern man. She would be short and weigh <140 lbs, but that would not be flab. And she would be coordinated and quick.