Resistance Training Series For Boxers... Cont' Part 2

At this point it should be understood that a well formulated resistance training program has to progress the body through various stages of adaptations to properly develop muscles and connective tissue to meet the desired goal(s). Related to the discussion is the need to have a basic understanding that there are different types of muscles with varying chemical and mechanical properties. The two main categories of muscles are type I and type II. Their specific characteristics are as follows:

Type I muscle fibers (slow twitch)

• produce low levels of force,


• slow to fatigue,


• long term contractions (stabilization),


• high capacity to deliver oxygen,


• small in size compared to type II muscle fibers,


• contain more capillaries, mitochondria (cell organelle that converts food to energy) and myoglobin.

Type II muscle fibers (fast twitch)

• produce high levels of force,


• fast to fatigue,


• short term contractions (strength and power),


• low capacity to deliver oxygen,


• larger in size compared to type I muscle fibers,


• contain less capillaries, mitochondria and myoglobin.

Type II muscle fibers are sub-divided into type IIa and type IIb. Type IIa muscle fibers have a higher oxidative capacity (ability to utilize oxygen), thus they fatigue more slowly than type IIb muscle fibers.

Type I muscle fibers are slow to produce maximal tension, but they are highly resistant to fatigue. These fibers are important for muscles that produce long-term contractions vital to stabilization and postural control. An example, would be maintaining a balanced fighting stance. In comparison, type II muscle fibers quickly produce maximal tension, but they rapidly fatigue. These fibers produce high levels of force and power which is needed to punch hard and fast.

All muscles have a combination of fast twitch and slow twitch muscle fibers that vary depending on the muscle's function. So it is important to manipulate specific training variables (i.e. time, frequency, load, tempo, etc.) according to muscular requirements and desired adaptations.