Last summer I did a few adventure races and it wasn’t until
my final race of the season when I quickly transitioned from the bike to the
run that I really felt the fatigue in my quads. Here is a photo of that
transition.
 |
| Me, hiding the pain well |
I was running at this point but only got about 300-500m and
my quads completely seized up on me. “Doing
BRICK workouts didn’t prepare me for this” I thought. After walking for 50-100m they finally let go
and I was back on my way, experiencing borderline cramping at a less than
optimal running pace.
This year I hope to reduce the quad fatigue I experienced
last year, in hopes to improve my run time. Recently, I searched for articles and found
one that peaked my interest. It is a
study published by the Journal of Applied Biomechanics in 2011 which can be
found here. The authors manipulated seat tube angle (STA) and
hand position on the bars and looked at leg muscle activity.
The study had three STA’s, 73°,
76°, and 79°. The authors found that the one quad muscle
that crosses the hip, the rectus femoris, significantly increases in activity as
the STA increases. This is most likely
due to the increased anterior tilting of the pelvis. For every 3°
increase in STA, the pelvis tilted forward an average of 3°.
 |
| STA in yellow. This is not my mountain bike. lol |
The second variable the authors manipulated was the hand
position on the bars. The three hand positions
in order of most aerodynamic to least are Aero, Drops, and Hoods. They found significant increases in hamstring
activity when moving to a less aerodynamic position. They also found increases in quad activation
when moving to a more aerodynamic position, although it wasn’t
significant.
Last year during that race there was a long road section, and
although I was on my mountain bike I rode the majority of it in a mock aero
position with my forearms on the bars. This
may have contributed to my increased quad fatigue… or it means I need to train
harder. Either way further studies need
to be done to see if changes in muscle activation actually affect run
performance. But I’m not going to wait
for new studies, so I will definitely be playing around with STA and hand
position before I get out on the trails this season.
Until next time, stay healthy my friends!
Dr. Adam
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