Breathing produces chest motion 24 hours a day, hence it is ideal for continuous energy harvesting of up to milliwatt scale power levels. A soft band wrapped around the chest can extend by centimeters at relatively low force levels. A stiff band extends at higher force levels but with some discomfort to the user. Chest strain energy harvesters must balance power generation and the soft tissue compression associated with user discomfort. This paper explores the modeling and analysis of wearable chest strain energy harvesters that use electromagnetic generators and piezoelectric polymers including the effects of soft tissue compliance. Electromagnetic generators are shown to produce more power than piezoelectric polymers during deep breathing. During shallow breathing, however, the polymer harvester performs better because static friction and soft tissue compression limit power generation in the electromagnetic harvester.