Fibre Type and Sports Performance

Understanding the Relationship Between Fibre Type and Sports Performance

Fibre type differentiation can occur due to factors such as metabolic demands of training, genetic factors and functional demands (Segerstrom et al., 2011). Segerstrom et al., (2011) showed that peak exercise capacity is related to fibre type composition. Type 1 and type 11 fibres have specific niches when it comes to metabolic and performance demands. Type 1 fibres have a much higher endurance capacity due to influences such as a larger capillary density, mitochondrial content and myoglobin content (Maughan & Gleeson, 2010). Furthermore they have greater citrate synthase activity which is the rate limiting enzyme in the citric acid cycle for aerobic metabolism (Maughan & Gleeson, 2010). Comparatively, type 11 fibres have greater phosphorylation activity (better ability to breakdown glycogen), higher phosphofructokinase levels (rate limiting enzyme for glycolytic system) and greater myosin ATPase activity which is the rate limiting factor of force and speed of contraction (Maughan & Gleeson, 2010). These metabolic properties suggest that type 1 fibres lend themselves to sports requiring greater endurance capacity and type 11 fibres have a greater requirement for fast, power based sports. Fry et al., (2003) demonstrated that weightlifters have a high percentage of type 11a fibres due to the requirement of large motor unit recruitment and fast muscle activity to generate large forces. Furthermore, Mcartney et al. (1983) showed the relationship between type 11 fibres and higher power outputs, illustrating that higher power output requirements are related to higher type 11 fibre content. In contrast type 1 fibres are commonly deemed “slow-twitch” and higher levels of type 1 fibres are correlated with a higher VO2 max (Parikh et al., 2008).  In well trained cyclists cadence rate is dependent on fibre type distribution (Segerstrom et al., 2011). Increasing cadence allows cyclists with higher type 1 fibres to apply less force per pedal whilst working closer to VO2 peak; by decreasing total force requirements cyclists can decrease type 11 fibre requirement (Segerstrom et al., 2011).

As you can see different performance demands of the two different sports explains the divergent fibre types. An AFL player has a greater requirement for endurance capacity with long periods of running over the four quarter period. They require a more efficient aerobic metabolism and type 1 fibres have higher citrate synthase activity (rate limiting enzyme for aerobic metabolism), making them more effective for the requirements of their sport.  Type 1 fibres also have greater succinate dehydrogenase activity which works as a major enzymatic reaction in the citric acid cycle (Maughan & Gleeson, 2010). Furthermore the force and power requirements for an AFL player are less than that of a rugby player as type 1 fibres don’t contract as quickly due to lower myosin ATPase activity and slower calcium release and uptake (Keeney, Wilmore & Costil, 2009). This indicates a slower cross-bridge cycling turnover which relates to a less developed glycolytic system. Whereas a rugby forward plays to produce force in the scrum and does short fast runs to gain quick metres. Their training would be more explosive in nature, with greater requirement for force and power output. Type 11 fibres have greater myosin ATPase activity which allows for faster cross-bridge cycling and fast calcium uptake and release from the sarcoplasmic reticulum (Kenney, Wilmore & Costill, 2009). Harrison & Bourkr (2009) showed that resisted sprint training in rugby players had a significant increase in the ability to develop force, speed and power. Therefore it makes sense that a rugby player would have a higher proportion of type 11 fibres with a greater requirement to generate force. Relating to performance capacity, a forwards anaerobic system is going to be far more developed, type 2 fibres having greater phosphorylase activity, which gives them a greater capacity for glycolysis.

By Lisa Campbell – AEP, AES, ASCA, SMA

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https://starttraining.net.au/996-2/

References

Fry, A. C. (2003). Muscle fibre characteristics and performance correlates of male Olympic-style weightlifters. Journal of strength and conditioning research, 17(4), 746-754

Harrison, A. J. & Bourkr, G. (2009). Effect of resisted sprint training on speed and strength performance in male rugby players. Journal of strength and conditioning research, 23(1), 275-283

Kenney W. L., Wilmore, J. H., Costill D. L. (2012) Physiology of Sport and Exercise (5th Edition). United States of America

Maughan, R. & Gleeson, M. (2010). The Biomechanical Basis of Sports Performance, New York, NY: Oxford University Press

Parikh, H., Nilsson, E., Ling, C., Poulsen, P., Almgren, P., Nittby, H., Eriksson, K. F., Vaag, A., & Groop, L. C. (2008). Molecular correlates for maximal oxygen uptake and type 1 fibres. American Journal of Endocrinology Metabolism, 294: E1152–E1159. Doi:10.1152/ajpendo.90255.2008

Segerstrom, A. B., Holmback, A. M., Hansson, O., Elgzyri, T., Eriksson, K. F., Ringsberg, K., Groop, L., Wollmer, P., Thorsson, O. (2011). Relation between cycling exercise capacity, fibre-type composition, and lower extremity muscle strength and endurance. Journal of strength and conditioning research, 25(1),16-22