Another way of saying that his strength left him
is that the Lord left him,
which is confirmed in Judges 16:20. The Lord is the one who supplies his strength. The Philistines seem to have thought that Samson’s strength is magical, and so they believed his lies about fresh thongs, new ropes, and braided hair. (This also suggests that Samson is not an exceptionally muscular man, because if he were, the Philistines would not have wondered what made him so strong.)1 But Samson’s hair is not magical, and therefore he does not lose his strength because of some magical manipulation. Rather, he loses his strength because of the withdrawal of the Lord’s presence, which is a striking reversal of the pattern described in Judges 2:18, where the Lord was with the judge.
2
19 She made him sleep on her knees. And she called a man and had him shave off the seven locks of his head. Then she began to torment him, and his strength left him.