lactic acid
Chyme
Muscle Cells
The answer your looking for is muscles however these do activly stretch they can only contract. They are increaset in length by the contraction of a counteracting muscle.
Whenever we perform an action muscles and bones help us to perform that work. This work done consist of 2 :- action and reaction muscles contract abd than relax to perform this work.
Erector spinae muscles
Muscle cells produce lactic acid during anaerobic fermentation. A buildup of lactic acid cause your muscles to feel tired.
A muscle is either contracting (doing work) or relaxing (not under tension). Some muscles do not ever completely relax under normal conditions.
Relax. Muscles can only work by contracting (tensing). When an opposite force is desired, an opposite muscle contracts.
the coulor
Muscles relaxing and contracting.
By contracting muscles in their body.
Muscles relaxing and contracting.
Kegels
The answer is "True"
Diaphragm and intercostals
Contracting or contracted. Related Information: When any muscle bulges it is contracted. Muscles work by contracting , and as they contract, the y bulge . As they relax again, they elongate, causing the bulging to subside.
What happens when a muscle shortens is that it is contracting. This is when the fibers of the muscles generate tension.