How Your Tendons, Ligaments and Muscles Work Together to Keep You Strong and Healthy

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Like the muscles in your body, ligaments come in all shapes: While some ligaments are stringy, others look more like wide bands, according to the Institute for Quality and Efficiency in Health Care. Ligaments are made of connective tissue and contain high amounts of collagen, a protein that helps the ligaments stretch and heal after injury, according to the Nemours Foundation.

Ligaments help keep structures of the body in place, often connecting two bones together at the joints. You can think of your ligaments like ropes that stabilize the bones and joints. This tissue helps you avoid twisting too much, preventing dislocation.

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While ligaments help hold your bones and joints in place, tendons connect muscles to bone, according to the Institute for Quality and Efficiency in Health Care. Like ligaments, tendons are made up of connective tissue and are highly resistant to tearing and stretching.

The reason you can take a sip of coffee or pick a pen up is due in large part to your tendons, which act as active support structures, according to Tyler Nightingale, a physical therapist at Bespoke Treatments in New York City. Unlike ligaments, you can strengthen tendons with progressive overload (gradually increasing the weight you lift over time), which encourages them to adapt and become stronger, explains Nightingale.

Your body has three different types of muscle tissue: skeletal muscle, smooth muscle and cardiac muscle, according to the Khan Academy.

• Skeletal muscle: The tissue attached to your bones that helps control movement. These are the muscles you can see and control.
• Smooth muscle: The tissue found inside hollow organs like the stomach or intestines.
• Cardiac muscle: The muscles found in the heart that help pump blood around the body.

Your skeletal muscle is closely connected with your tendons and ligaments and can be found in all shapes and sizes around the body. While a variety of muscles may be involved in a single motion, the primary muscle is known as the prime mover or agonist, according to Oregon State University. The muscle opposite the prime mover is called the antagonist, which maintains the body or limb position and controls rapid movement.

For instance, when you extend your leg at the knee, your quads (a group of four muscles) are triggered, serving as the agonists in the motion — they're the reason the leg extends. The antagonists of this motion are your hamstrings, which your body activates to slow or stop this motion.

Although your ligaments are strong and flexible, you can stretch them too far or tear them, causing a sprain to the joint, according to the University of Maryland Medical Center (UMMS). Sprains are a common injury and occur when a joint moves into an unnatural position, like twisting your ankle.

While ligaments become injured by unnatural movement, tendons become injured from overuse or repetitive motion, according to UMMS. Inflammation or micro-tearing of the tendon is called tendonitis and typically worsens with repetition, according to Nightingale. Tennis elbow or swimmer's shoulder are examples of tendonitis caused by a sport-related repetitive movement.

While muscle injuries aren't as common, they can occur if you place too much force on a specific muscle, causing a tear, according to the Hospital for Special Surgery. Once a muscle is injured, inflammation and swelling soon follow. If the tear is significant, there may be a complete rupture in the muscle, which would require surgery.

In order to keep your connective tissue healthy and injury-free, it's important to avoid doing too much too fast. As muscle develops more quickly than your tendons, you need to give your body time to adapt to new exercises. "There is no such thing as a bad exercise, just an exercise that you're not ready to perform," says Nightingale.

Read more: 5 Common Workout Injuries and How to Avoid Them