Cardiovascular Exercise Adaptations

Aerobic exercise causes important cellular and vascular changes including:

• Increased number of mitochondria (intracellular respiration). Simply put with more mitochondria, you can produce more energy (ATP).
• Your heart becomes more efficient. With each beat more blood is pumped to your body resulting in a increase of available oxygen.
• Capillary density increases. Resulting in an increased amount of oxygen and nutrient rich blood delivered to your muscles

Cardiovascular Development vs Detraining Rates

• These changes gradually occur in approximately 4-8 weeks.

• These beneficial adaptions disappear when you stop training. Detraining occurs approximately 2 times faster than the development rate.

• Not exercising for two to eight months leads to loss of virtually all fitness gains. The loss of aerobic capacity occurs much more rapidly than declines in muscle strength.

http://jap.physiology.org/content/60/1/95.short
http://circ.ahajournals.org/content/122/12/1221.short

Weight Training Adaptations

• When you start weight training, during the first 3-4 weeks strength gains are due to nervous system changes.

• You’re getting stronger due to an increase in muscle fiber activation (you’re training your brain to activate previously dormant motor neurons).

• In addition, you’re also training your nervous system to decrease activation of the opposing muscle group. Essentially you’re getting stronger without any change in muscle size.

• After 3-4 weeks strength changes are due to increase in muscle fiber diameter (called hypertrophy). A common misconception is that the number of muscle fibers is increasing (this is called hyperplasia).

Muscle Development vs Detraining Rates

• Detraining occurs differently with strength training. Neural changes remain, so a formerly conditioned person can regaining lost muscle mass faster compared to someone that has never weight trained.
• Muscle mass also takes approximately 2 times longer to lose than it takes to initially gain.

http://sci-fit.net/2017/detraining-retraining/
https://www.ncbi.nlm.nih.gov/pubmed/16464122

Cardiovascular Exercise Adaptations

Aerobic exercise causes important cellular and vascular changes including:

• Increased number of mitochondria (intracellular respiration). Simply put with more mitochondria, you can produce more energy (ATP).
• Your heart becomes more efficient. With each beat more blood is pumped to your body resulting in a increase of available oxygen.
• Capillary density increases. Resulting in an increased amount of oxygen and nutrient rich blood delivered to your muscles

Cardiovascular Development vs Detraining Rates

• These changes gradually occur in approximately 4-8 weeks.

• These beneficial adaptions disappear when you stop training. Detraining occurs approximately 2 times faster than the development rate.

• Not exercising for two to eight months leads to loss of virtually all fitness gains. The loss of aerobic capacity occurs much more rapidly than declines in muscle strength.

1. http://jap.physiology.org/content/60/1/95.short
   
2. http://circ.ahajournals.org/content/122/12/1221.short

Weight Training Adaptations

• When you start weight training, during the first 3-4 weeks strength gains are due to nervous system changes.

• You’re getting stronger due to an increase in muscle fiber activation (you’re training your brain to activate previously dormant motor neurons).

• In addition, you’re also training your nervous system to decrease activation of the opposing muscle group. Essentially you’re getting stronger without any change in muscle size.

• After 3-4 weeks strength changes are due to increase in muscle fiber diameter (called hypertrophy). A common misconception is that the number of muscle fibers is increasing (this is called hyperplasia).

Muscle Development vs Detraining Rates

• Detraining occurs differently with strength training. Neural changes remain, so a formerly conditioned person can regaining lost muscle mass faster compared to someone that has never weight trained.
• Muscle mass also takes approximately 2 times longer to lose than it takes to initially gain.

1. https://www.researchgate.net/publication/50401359_An_examination_of_the_time_course_of_training-induced_skeletal_muscle_hypertrophy
   
2. http://sci-fit.net/2017/detraining-retraining/
   
3. https://www.ncbi.nlm.nih.gov/pubmed/16464122