Strength-training routines can exploit these characteristics, through the use of bands and chains. Bands progressively increase resistance as they're stretched

Strength-training routines can exploit these characteristics, through the use of bands and chains. Bands progressively increase resistance as they're stretched. Chains load or de-load resistance as they're raised or lowered to the ground. (How much of this was known and utilised during mediaeval warfare training and drilling is unclear, but I suspect the answer is "little".)