King James Bible
"Even the youths shall faint and be weary, and the young men shall utterly fall:"
Isaiah emphasizes that even those at the peak of human vitality—the young with their natural energy and stamina—will eventually exhaust their strength. This underscores the universal limitation of human power, regardless of age or vigor. The progression intensifies from fatigue to complete collapse, with 'utterly fall' suggesting total failure of strength. In the context of Isaiah 40, this human frailty sets up the contrast with God's inexhaustible power that renews those who wait on Him (v. 31).