Question

After 3 months of endurance training John (who you may remember from Applied Essay 3 is not very fit; initial VO2 max of 35.0 mL·kg-1·min-1) could not believe how much further he could run without having to stop. Initially he could barely get around the track once…now he can run 12 laps of the track (3 miles) at a pace he could barely maintain for 1 lap a few months earlier. Although the training likely increased his VO2 max (much of which is explained by central adaptations taking place within his cardiovascular system such as increased stroke volume, etc.) what other perhaps peripheral adaptations have occurred that allow him to operate at a much higher intensity for much longer periods of time?

Not only did John start running but he also started performing a structured resistance training program on his upper body (mainly the bench press). John initially experienced large increases in his upper body strength virtually every time he went to the gym and was overjoyed. However, after 2 months his strength gains began to level out and John became a bit demoralized. He was getting stronger, but at a much, much slower rate. What is the explanation for John’s early strength gains and what has to happen in the longer-term for John to now keep getting stronger? Compare and contrast these two time periods...what causes strength gains in the short-term compared to the long-term? If he continues training long enough will John experience hypertrophy, hyperplasia, or both? Make sure to define these terms.

Answer 1

The average untrained healthy male have a VO2 max of approximately 35–40 mL/(kg·min), that John had months back. However, with long term endurance training, his VO2 max got increased, which was the result of physiological adaptations both central (cardiovascular) and peripheral

Improved glycogen and fat storing capabilities in muscles ----This allowed an increased heat dissipation during intense exercise, thus lengthening the time of work out.

• Capillarization ---This increased the surface area of arterial and venous capillaries, thus helped in heat dissipitation during heavy work-out.
• Catabolism ----It heightened his capacity to use fat and glycogen stores as energy.
• Development of slow twitch (type 1) fibers ---These increased efficiency and resistance to fatigue.
• Oxidative enzymes ---Which may break-down nutrients to create ATP, and thus providing energy.
• John started resistance training, the exercises affected his muscles by increasing the formation of myofibrils, thereby increasing the thickness of muscle fibers. This added structure causing hypertrophy, or the enlargement of muscles (as Hypertrophy is defined as an increase in muscle mass due to the addition of structural proteins). As he was doing bench press, his upper body strength increased. Tendons were also become stronger to prevent tendon damage, as the force produced by muscles is transferred to tendons that attach the muscle to bone.

• Now, let me tell you that in general terms:

• Hypertrophy is an increase in the size of the cell (muscle fibre); while
• Hyperplasia is an increase in the number of cells (muscle fibers).

• Physical training alters the appearance of skeletal muscles and can produce changes in muscle performance. Although muscle cells can change in size, new cells are not formed when muscles grow. Thus, John may experience hypertrophy with long-term resistance training but not hyperplasia.