Effect of Seat Tube Angle and Exercise Intensity on Muscle Activity Patterns in Cyclists

Jed Williams Research Review

In 2017 authors Duggan, Donne and Fleming sought to further investigate the effect that changing seat tube angle (STA) had on muscle activity patterns particularly when coupled with exercise intensity. In the literature review that they performed they found that increasing STA decreased the amount of work that the cardiovascular system had to perform at the same work rates. This was shown with reduced heartrate (HR) and amount of oxygen consumed by the body (VO2). When looking at efficiency at submaximal intensities a lower VO­ is preferable as it indicates that the body isn’t working as ‘hard’ to produce the same power. It has also been proven that increasing STA has a positive effect on subsequent 10 km running time (Garside and Doran, 2000). The authors note that although several studies have found that STA can influence muscle recruitment patterns, the muscles which are affected by changing STA are not always the same.

This study took 11 competitive cyclists and looked at they responded when exercising at 160W and an individualised workload (IWL); determined by some maximal exercise testing, with STA’s of 70°, 75°, 80°.

They measured VO2 giving them the ability to look at the economy of each position with the goal being to find the lowest VO2 for a given workload. Also measured were: blood lactate, heart rate, EMG thigh muscle data.


Retrieved from Duggan, W., Donne, B., & Fleming, N. (2017). Effect of Seat Tube Angle and Exercise Intensity on Muscle Activity Patterns in Cyclists. International journal of exercise science10(8), 1145-1156.

The results showed that there was a change in muscle recruitment patterns as STA changed. The most interesting being that as STA increased it caused the muscles in the front of the thigh to activate later in the pedal stroke. This change of timing increased the amount of time they were active in the ‘key force generation phase’.

The bike fit applications for this research are that it provides evidence and rationale for increasing STA. This is particularly noteworthy when fitting riders to whom high power is a priority such as time trialists, track riders and triathletes. The impact STA can have on a rider’s centre of mass should not be dismissed however as this can drastically affect other aspects of the fit such as reach, and the amount of weight loaded through the hands.