Understanding Muscle Strength & Resistance

What is Strength?

Strength is the capacity to overcome resistance through muscular action.

Types of Strength

• Force-Resistance: Capacity used for multiple repetitions against prolonged resistance. Loads are light/medium.
• Explosive Force: Capacity to overcome a load with muscle contraction velocity. Done in the shortest time possible.
• Maximum Force: Capacity to oppose a maximum load through voluntary muscle contraction. May involve motion or not.

The Locomotor System

The locomotor system is formed by bones, muscles, and joints. Muscles cover bones. They are formed by fascicles, muscle fibers, myofibrils, and myofilaments (actin and myosin). The function of an agonist muscle is to stretch when its antagonist contracts.

Muscle Contractions

Types of Contractions

• Concentric Isotonic Contraction: Production of shortening in the total length of the muscle.
• Eccentric Isotonic Contraction: Muscle length increases due to tension in its elastic parts.
• Isometric Contraction: The contractile structures of the muscle shorten and the elastic ones lengthen. Thus, the muscle length remains constant.

Benefits of Strength Training

• Muscle hypertrophy
• Correct postural attitude
• More resistant bones

What is Resistance?

Resistance is a physical capacity that allows carrying out a job for a prolonged time, delaying the appearance of fatigue.

Characteristics of Aerobic Activity

Aerobic sports activities have 4 characteristics:

• Need large muscle groups
• Done at moderate intensity
• Prolonged duration
• Cells use fuels obtained with oxygen presence

Types of Resistance

• Anaerobic Resistance: High or maximum intensity, oxygen reaching muscle cells is insufficient during activity, generates oxygen debt, limited duration.
• Aerobic Resistance: Low or medium intensity, oxygen reaching cells is sufficient, no oxygen debt, prolonged duration.

Systems Involved in Resistance

Respiratory System

The respiratory system facilitates gas exchange.

Positive Changes from Aerobic Sports Activities

• Increased lung capacity
• Better oxygen uptake by muscles
• Better respiratory muscle work

Cardiovascular System

The cardiovascular system is the motor that circulates blood throughout the body. It is formed by the heart and blood vessels. Exercise increases heart rate.

Effects of Aerobic Sports Activities

• Heart hypertrophy
• Bradycardia
• Reduces arterial tension
• Increases size of capillaries

Heart rate is the measure of how fast the heart beats and indicates exercise intensity.