An overview of morphological and functional characteristics of different muscle fiber types (Weineck, 2004)
by Nizar Abu-Hamdeh
| Morphological / Functional Parameter | Type I | Type IIc/IIa | Type IIb |
|---|---|---|---|
| Motoneuron, Diameter | approx. 30 µm | 40-60 µm | up to 70 µm |
| Activation Treshold | low | middle | high |
| Nerve Fiber, Diameter | approx. 9 µm | 10-15 µm | approx. 20 µm |
| Axonal Transmission Speed | 30-40 m/s | 40-90 m/s | 70-120 m/s |
| Frequency of Discharge | up to 30 Impulses/s (continous) | up to 90 Imp/s | up to 150 Imp/s (in bursts) |
| Muscle Fiber Transmission Speed | approx. 2,5 m/s | approx. 3-5 m/s | approx. 5,5 m/s |
| Muscle Fiber Force (Single Twitch) | 70 mg | 80-90 mg | 100 mg |
| Muscle Fiber Force (tetan. Contraction) | approx. 140 mg | approx. 400 mg | approx. 700 mg |
| Cross Section | 2000-4000 µm² | 2000-6000 µm² | 2000-10 000 µm² |
| Fatigue Resistance | high | low | low |
| Contraction Speed, Single Twitch | approx. 100 ms | 50-90 ms | approx. 40 ms |
| Contraction Speed, Ballistic Contraction | approx. 150 ms | 80-140 ms | approx. 60 ms |
| Force / Motor Unit | 2-13 gr | 5-50 gr | 30-130 gr |
References:
Weineck, J.: Optimales Training. Leistungsphysiologische Trainingslehre unter besonderer Berücksichtigung des Kinder- und Jugendtrainings. 14. Aufl. Spitta Verlag, Balingen 2004.