Both groups increased in maximal isometric strength, and the % increase was significantly greater in the control than cooled group. However because it was a short study as you indicated both groups did not gain any muscle. In terms of the small increase in brachial artery diameter, for 4-6 weeks time that is still substantial.
I think overall this is one of the first studies analyzing the effects of cooling on endurance and strength indices and thus far the tendency is for it to have detrimental effects on a number of variables, and this is a short term study. THis to me is cause for more studies further analzying if this attenuates strength and muscle gains in more long term studies, it is also cause for alarm for us to begin to consider the true implications of icing vs. non icing particularly with all the new data comming out on variables such as changes in heat shock protein expression