Table 1.

Biological characteristics of muscle fiber types¹ [6].

	I	IIA	IIX	IIB
Contraction speed	+	+++	++++	+++++
Myofibrillar ATPase	+	+++	++++	+++++
Contraction threshold	+	+++	++++	+++++
Contraction time per day	+++++	++++	+++	+
Fatigue resistance	+++++	++++	++	+
Oxidative metabolism	+++++	++++	++	+
Glycolytic metabolism	+	++++	++++	+++++
Phosphocreatine	+	+++++	+++++	+++++
Glycogen	+	+++++	++++	+++++
Triglycerides	+++++	+++	+	+
Phospholipids	+++++	++++	+++	+
Vascularization	+++++	+++	+, ++	+
Myoglobin	+++++	++++	++	+
Buffering capacity	+	+++	+++++	+++++
Z line width	+++++	+++	+++	+
Diameter	++	+, ++	++++	+++++

  ¹+: very low; ++: low; +++: medium; ++++: high; +++++: very high.