A friend and I were discussing the apparent lower heart rates noted while riding
in the aero position vs riding in the traditional road bike position.
One answer to this is that your upper body is in a horizontal position,
thus requiring your heart to work less to pump blood.
Similar to lying down in bed. Seems to make sense.
Does anyone know of any studies that can validate this? Thanks
Are you holding cadence the same? I’d guess that as the likely cause at first pass.
Lots of ways to explain this.
Are you riding the same effort?
Are you more open, allowing more efficient blood return from the legs, allowing more filling to occur, which would allow more stroke volume, hence lower HR for the same effort?
Are you using more muscle mass supporting your body in the “road bike position” vs the “aero position”, which is presumbably using aero bars?
Med Sci Sports Exerc. 1997 Jun;29(6):818-23
Influence of different racing positions on metabolic cost in elite cyclists. Gnehm P, et al. VO2 and HR values in aero position were significantly higher by 1.5 mL.kg-1.min-1 and 5 beats.min-1, respectively, compared with upright position. We concluded that riding a bicycle in an extreme aero-position increases the metabolic cost of cycling when wind resistance is not taken into account. However, when the mechanical power losses of 9 W (estimated by the VO2 increase) are compared with the expected aerodynamic power savings of approximately 100 W, it appears that aerodynamic advantages by far outweight their metabolic cost.
noish ~aka the pubmed bandit
There is actually evidence (can’t remember the citation off hand) showing an increase in HR in the aero position at a given workload possibly due to the increase load on the upper body and supporting musculature. However this study was done in a lab so aerodynamics were not a factor. If you are comparing your heart rates on road bike vs. tri bike at a given speed your heart rate on the tri bike would proably be lower because the aerodymanic advantage would outweigh the small increase in heart rate due to the upper body loading. You would really need to ride both your road bike and tri bike at the same work load (wattage) using a power meter to make any meaningful comparisons of HR in the real world.
Thanks for the replies.
I see the obvious differences with road bike vs tri bike.
I do ride w/ a Power Tap and see that that would definitely give
measurable data, watts.
Also I feel I am in better shape this year than last, so that is a factor too.
I was curious if there have been any studies, as the one mentioned above.
Thanks.