Woman carrying wood and her baby in Uganda<unk>  is the physical or perceived use of energy.<unk>  traditionally connotes a strenuous or costly effort, resulting in generation of force, initiation of motion, or in the performance of work. It often relates to muscular activity and can be quantified, empirically and by measurable metabolic response.
Exertion
Banding 
Logrolling 
Clipping 
Stabbing
Retching
Cocooning 
Inoculation