Consider the marvels of modern transportation. By plane, one can travel to almost anyplace on the earth in less than 24 hours. In Isaiah's day, before travelers retired, they would change into sleeping attire, which necessitated the loosening of 'the girdle of their loins' and the removal of their shoes by breaking the shoe latchet. Isaiah sees that travelers in the last days would never need to change into sleeping attire; rather, they could travel across the globe without needing any sleep.
"Isaiah saw many other things in connection with this gathering. He saw that the Lord would gather Israel quickly and with speed, that they would not even have time to loosen the shoe latchets of their shoes, or to slumber or sleep. (See Isa. 5:27) Imagine a statement like that way back in the days of Isaiah, thousands of years ago, with their means of transportation at that time!" (Ensign, Nov. 1975, 50 as taken from Commentaries on Isaiah in the Book of Mormon, ed. by K. Douglas Bassett, [American Fork, UT: Covenant Publishing Co., 2003], 116)