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. 2021 Oct 23;4(1):29-37.
doi: 10.1016/j.smhs.2021.10.007. eCollection 2022 Mar.

Muscle recruitment patterns and saddle pressure indexes with alterations in effective seat tube angle

Reece McDonald  1 , Wendy Holliday  1 , Jeroen Swart  1
Affiliations

Muscle recruitment patterns and saddle pressure indexes with alterations in effective seat tube angle

Reece McDonald et al. Sports Med Health Sci. .

Abstract

Alteration of the effective seat tube angle (ESTA) may affect muscle activation patterns of the lower limbs in cycling. There is conflicting evidence due to inadequate kinematic controls in previous studies. The primary aim of this study was to determine the muscle activity of seven lower limb muscles during alterations of the ESTA by altering the position of both the handlebars and saddle forwards or backwards by 3 ​cm while ensuring controlled kinematics. Secondly, to determine the effect on the saddle pressure indexes. Ten participants performed two 5 ​min electromyography (EMG) trials at 70% of peak power output (PPO) for three consecutive visits. There was a significant increase in muscle activity in the biceps femoris, gluteus maximus, and medial gastrocnemius with reductions in ESTA while a significant increase in tibialis anterior with increases in ESTA was observed. Saddle pressure indices demonstrated a significant change in frontal versus back pressure as well as mean pubic pressure with changes in ESTA. Alteration in the ESTA affects muscle activity in some, but not all of the lower limb muscles. Further research needs to be conducted to adequately understand the mechanism behind the differences in muscle activation.

Keywords: EMG; Muscle recruitment; Pressure mapping; Seat tube angle.

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Conflict of interest statement

The authors have no conflict of interest to declare.

Figures

Fig. 1
Fig. 1
Demonstration of the four standard measurements. The saddle height, saddle setback, handlebar reach and handlebar drop.
Fig. 2
Fig. 2
Electromyographic data for the backwards, preferred and forwards positions. A. Gluteus Maximus ∗ p ​= ​0.0013 (backwards vs. forwards); #p ​= ​0.02 (preferred vs. forwards); †p ​= ​0.001 (preferred vs. backwards; B. Biceps Femoris ∗ p ​= ​0.0002 (backwards vs. forwards); #p ​= ​0.0028 (preferred vs. forwards); †p ​= ​0.0039 (preferred vs. backwards); C. Medial Gastrocnemius ∗ p ​= ​0.011 (backwards vs. forwards); D. Tibialis Anterior #p ​= ​0.0096 (preferred vs. forwards).
Fig. 3
Fig. 3
Saddle pressure mapping data. A. Front versus rear pressure ratio in the backwards, preferred and forwards positions. ∗p ​= ​0.017 (backwards vs. forwards); B. Mean pubic pressure in the backwards, preferred and forwards positions. ∗p ​= ​0.04 (backwards vs. forwards); †p ​< ​0.01 (preferred vs. backwards).
Fig. 4
Fig. 4
Electromyographic data for the backwards, preferred and forwards positions in the A. Vastus Lateralis, B. Vastus Medialis and C. Rectus Femoris.
See this image and copyright information in PMC

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