Contraction & Stretching in Muscle Tissue

Muscles contract and stretch in cooperative movements with each other. When one muscle group contracts and gets shorter, your opposite muscle group extends and lengthens. Muscle contraction occurs through lifting, pushing and pulling against a form of resistance, such as your body weight. As such, muscle strength and flexibility are both important for health and athletic performance. Stretching your muscles improves your flexibility and range of mobility, which helps prevent injuries and can improve your athletic performance.

Muscle Cooperation

• Pairs of muscles work together in agonist-antagonist relationships. For example, when your knee bends, your hamstring muscle contracts, while your quad lengthens and relax. This makes the hamstring muscle is the agonist, or prime mover, in the relationship, and the quad the antagonist. If you straighten your knee, the quad will contract and your hamstring will lengthen. Agonist-antagonist-related muscles are usually on opposite sides of a joint. Among these include the pecs and lats, abs and lower back muscles, triceps and biceps, the obliques on opposite sides of each other, as well as the hamstrings and quads.

Concentric vs. Eccentric

• There are two different types of muscle contractions: concentric contractions, which shorten the muscle exerting force, and eccentric contractions, which lengthen the muscle exerting force. Muscles contract concentrically when they are being actively used to lift, push or pull weight. For example, lifting a dumbbell for a bicep curl causes the bicep muscle to contract concentrically. When the load is too heavy for a muscle, it will contract eccentrically. When your muscles are in a lengthened, or eccentric, contraction, they can hold more weight than if they were concentrically contracting That's why it's easier to set down a heavy object than to lift it.

Muscle Stretching

• Flexibility refers to the muscle's range of mobility. Improving your flexibility will promote muscle health by relaxing and loosening tight muscles. It will also help protect your muscles from injury. Your muscles and tendons have receptor nerves that monitor muscle length and keep them from being over-stretched. Muscles are more flexible when they're warm, and become stiff when cold, so stretch your muscles after warming up to increase muscle tissue temperature.

Static vs. Dynamic Stretching

• There are different ways to stretch your muscles. Static stretching is holding a stretch without moving your muscles for 15 to 30 seconds at a time. It's effective and safe as long as your muscles are warm before you stretch. For example, to stretch your hamstrings, stand with your feet together and bend at the hips to try to touch your toes. Dynamic stretching means stretching while your body is in motion; it can help loosen tight muscles. Static stretching increases the risk of muscle tearing, while dynamic stretching is considered safer and healthier for your muscles because it gets them warm while stretching them. According to the website Sports Fitness Advisor, static stretching can be harmful for athletes who do sports requiring powerful, explosive movements. Dynamic stretches often mimic different movements in sports in exaggerated but controlled motions. For example, walking straight leg kicks and walking lunges are dynamic stretches.