Matthew Poole and continuators on Lamentations 3:7

7 He hath hedged me about, that I cannot get out : he hath made my chain heavy .

The use of an hedge about an inclosed field, is twofold: To keep out other beasts, which belong not to the owner of the ground; in this sense God set an hedge sometimes about Canaan, Isa. 5.5. 2 To keep in those beasts that are within, thus God had now hedged them in, into a barren place where they had no pasture, but were continually pushed at by other beasts with whom they were mixed, and who were stronger than they, and they could not get out.

God had dealt with them as with grievous Malefactors, who are loaded with heavy Chains. He had made their affliction heavy and insupportable.

Marginal references: Job 3.23. & 19.8.