Adaptations to Resistance Training

Mechanisms of Muscle Strength Gain

• Neural adaptations, hypertrophy, and changes in muscle architecture are mechanisms of muscle strength gain.
• Muscle strength gain can occur without hypertrophy (increase in muscle size).

Muscle Strength Gain and Hypertrophy

• Strength gain can occur within 3-6 months of resistance training, with an average gain of 20-40%.
• Older adults tend to have greater absolute strength gains after resistance training.
• An essential element for muscle strength gain is progressive overload (gradually increasing weight or resistance).
• Synchronous recruitment of motor units facilitates increased muscle force production.

Muscle Physiological Responses

• Autogenic inhibition is a reflex response that reduces motor neuron activity to prevent muscle damage.
• The primary factor that contributes to muscle hypertrophy is progressive resistance exercise.
• Testosterone is a hormone that facilitates fiber hypertrophy.
• The main factor that contributes to muscle strength gains in the long term is neural adaptations.

Detraining and Muscle Loss

• During detraining, muscle structure and function deteriorate, with a daily strength loss of approximately 0.5-1% during the first week.
• Type II (fast-twitch) muscle fibers are affected more than Type I (slow-twitch) fibers during detraining.
• It generally takes 4-6 weeks to regain lost strength after detraining.

Nutrition for Muscle Growth

• The recommended protein consumption after resistance exercise for muscle growth is 15-30 grams.
• The recommended daily protein consumption for increasing muscle mass is 1.6-2.2 grams/kg body weight.

Fiber Type Conversion and Resistance Training

• Fiber type conversion is possible under conditions of high-intensity, low-repetition resistance training, or high-volume, low-intensity resistance training.
• Resistance training is recommended for children and adolescents, as it promotes muscle growth and strength gain.

Older Adults and Resistance Training

• The primary factor responsible for increases in strength in older adults is resistance training.