Introduction to Force, Stength, Power

Semester 2, week 1

What are the mechanisms of muscle strength gain?

• Resistance training

• Hormones

• Genetics

• Fibre hyperplasia

• Motor unit recruitment

What happens to protein metabolism during and after exercise?

• During exercise: decreased synthesis, increased degradation

• After exercise: increased synthesis, decreased degradation

How do hormones increase muscle strength?

Testosterone facilitates fibre hypertrophy (natural anabolic steroid hormone)

What do synthetic anabolic steroids do?

Result in large increases in muscle mass

What is an example of how genetics are a mechanism of muscle strength gain?

Mutation in myostatin gene (Belgium Blue cows). In Belgian Blue, a loss-of-function mutation in the myostatin (MSTN) gene prevents myostatin from limiting muscle growth, resulting in excessive muscle development known as “double muscling”

What is fibre hyperplasia?

Most hypertrophy is due to fibre hypertrophy. Fibre hyperplasia is fibre splitting, each half grows to the size of parent fibre (parent size may also contribute, there is some evidence in animal studies but very little evidence in humans)

What is motor unit recruitment?

Strength gain that can occur without hypertrophy. Normally motor units are recruited asynchronously. With resistance training, there is more synchronous recruitment which increases strength (improved rate of force development)

What are the different types of muscle contraction?

• Concentric

• Eccentric

• Isometric

What is a concentric movement?

The muscle shorterns while producing force. It usually occurs when lifting or accelerating a load. For example, the upward phase of a bicep curl

What is an eccentric movement?

The muscle lengthens while still producing force. It usually occurs when lowering or controlling a load. For example, lowering a dummbell in a bicep curl

What is an isometric movement?

The muscle produces force without changing length. No visible joint movement occurs, however, tension is generated, the muscle stays the same length. For example, holding a dumbbell still