NETA Personal Trainer Practice Exam 2026 – Comprehensive All-in-One Guide to Achieve Certification Success!

Type 2b (or 2x) muscle fibers are characterized by their low resistance to fatigue, making them suitable for short bursts of high-intensity activities rather than prolonged endurance efforts. These fibers contain fewer mitochondria and less myoglobin compared to other fiber types, which means they rely more on anaerobic metabolism for energy production. This reliance on anaerobic pathways allows them to generate quick, powerful contractions but also leads to quicker depletion of energy stores, resulting in fatigue.

The other options describe characteristics of muscle fibers that do not accurately represent the nature of Type 2b fibers; for instance, their high resistance to fatigue relates more closely to type 1 fibers, which are built for endurance.