The Physiological Adaptations caused by Resistance and Endurance Training

So many of us train because we know it is good for us or because we enjoy it. But do you really know which changes are taking place inside your body besides your muscle just getting bigger or your body getting fitter. I will discuss some of the changes taking place in the body focusing on resistance (weight) training as well as cardiovascular training.

Resistance training

The major adaptations of resistance training is an increase in the cross sectional area of muscle (Brooks et al, 2005), this is when a muscle becomes bigger (hypertrophy) and an increase in strength. This muscle hypertrophy leads to an increase in maximum force generating capacity by these muscles. Another important adaptation is the thickening of bones due to resistance training. Bone tissue becomes stronger through increased deposition of mineral salts and production of collagen fibers (Tortora and Derrickson, 2006). There is also an increased neural function due to resistance training. This is to do with motor units. There is an increase in the electrical activity of the muscle and an increase rate of motor unit stimulation. This means the muscle is able to engage sooner and with more muscle fibers being activated sooner. Some other adaptations according to Brooks et al 2005 include:

1. ­ Increased contractile capacity of muscle
2. ­ Increased anaerobic power
3. Ligament and tendon strenght may increase ­
4. ­Increased capacity to use lipids (fats) as fuel
5. Increased capillary density = more blood and oxygen delivery to muscles
6. Increased stores of glycogen in muscle = more glucose can be produced for energy
7. ­ Increased intramuscular high energy compounds

Cardiovascular training

The major adaptations for cardiovascular training take place in the heart. With cardiovascular or endurance training the cardiac output (amount of blood pumped by heart in liters.min-1) of the heart will decrease. This is due to an incresed stroke volume which is the quantity of blood ejected out of the heart with each beat (Baechle and Earle, 2008). So if the quantity of blood being ejected from the heart each beat is increased cardiac output can then decrease. Due to an incresed amount of blood being pumped during each contraction (stroke volume) the heart will contract less frequently and thus there is a decreased heart rate with endurance training. Some other adaptations according to Baechle and Earle, 2008 include:

1. Increased muscular endurance and aerobic power
2. ­Increased capillary density
3. Increased mitochondrial density = more ATP = more energy
4. Increased metabolic energy stores
5. Increased ligament and tendon strength
6. Decreased % body fat

These are just a few changes that take place in the body following resistance and cardiovascular training and perhaps you can think about it next time you go training.

Best Regards
Shane Scott

References:

Baechle T.R. and Earle R.W. (2008). Essentials of Strength Training and Conditioning. 3rd Edition. Human Kinetics. USA, 120-130.

Brooks G.A., Fahey T.D. and Baldwin K.M. (2005). Exercise Physiology: Human Bioenergetics and Its Applications. 4th Edition. Mcgraw-Hill. New York, 431-473.

Tortora G.J. and Derrickson B. (2006). Principles of Anatomy and Physiology. 11th Edition. John Wiley & Sons Inc. USA, 188.