IB Sports, exercise and health science A.3.2.2 Effects of Physical Activity on the Muscular and Immune Systems Notes

How physical activity affects the muscular system

Exercise improves strength, endurance, and muscle size

Regular physical activity increases muscle strength, improves endurance, and can cause hypertrophy.

Muscle Strength

1. Muscle strength refers to the ability of a muscle or group of muscles to exert force against resistance.
2. Regular resistance training and weight-bearing exercises (such as lifting weights) stimulate muscle fibers, leading to increased strength.

Muscle Endurance

1. Muscle endurance is the ability of a muscle to perform repeated contractions over an extended period without fatigue.
2. Exercises such as running, cycling, and swimming enhance endurance by improving the oxidative capacity of muscle fibers.

Muscle Hypertrophy

1. When muscles are exposed to resistance or stress, such as lifting heavy weights, they adapt by increasing in size.
2. This is the result of muscle fiber repair after microscopic damage incurred during exercise.
3. Hypertrophy is most effectively achieved with moderate to high resistance and repetitions (typically 6-12 reps per set).

Excessive or improper exercise can damage muscle tissue

Improper or excessive exercise can harm the muscular system.

Overtraining

1. Overtraining occurs when an individual exceeds the body's ability to recover from intense physical activity.
2. This can lead to muscle breakdown, fatigue, and a decrease in performance. Signs include persistent soreness, reduced strength, and poor sleep.

Muscle Fatigue

This happens when the body's energy stores (such as glycogen) are depleted, leading to muscle exhaustion and a decline in performance.

Muscle Injuries

1. Muscle injuries such as strains, tears, or sprains are common, especially when exercise is done improperly or without a warm-up.
2. Overuse injuries, such as tendinitis, are common in athletes who perform repetitive movements.

How physical activity affects the immune system

Moderate exercise strengthens immune function

1. Moderate exercise improves immune function.

Enhanced Circulation of Immune Cells

1. Regular moderate physical activity boosts immune system function by improving the circulation of immune cells such as T-cells, B cells and macrophages, which play a crucial role in fighting infections.
2. Exercise increases blood flow, helping immune cells travel through the body more efficiently to detect and combat pathogens.