Final answer:
Eccentric actions, where muscles lengthen under tension, should be progressed smoothly to prevent strain. Sudden or abrupt movements can cause muscle injuries, so smooth progression is key for safety.
Step-by-step explanation:
Progression during eccentric actions should occur smoothly to reduce the risk of muscle strain. Eccentric actions refer to the lengthening contraction of the muscle, which happens when the muscle is lengthening under tension, such as when lowering a weight during a bicep curl. To prevent injury and strain, progressing through these movements in a controlled and smooth manner is critical, allowing the muscles to adapt to the tension and resistance without sudden shocks that could cause damage.