Physiological and biomechanical factors associated with elite endurance cycling performance
E. F. Coyle, M, E. Feltner, S, A. Kautz, M. T. Hamilton, S. J. Montain, A. M. Baylor, L. D. Abraham, and G. W. Petrek
In this study we evaluated the physiological and biomechanical responses of "elite-national class" (i.e., group I; N = 9) and "good-state class" (i.e., group 2; N = 6) cyclists while they simulated a 40 km time-trial in the laboratory by cycling on an ergometer for I h at their highest power output. Actual road racing 40 km time-trial performance was highly correlated with average absolute power during the I h laboratory performance test (r = -0.88; P < 0.001). In turn, I h power output was related to each cyclists' V02 at the blood lactate threshold (r = 0.93; P < 0.00 I). Group I was not different from group 2 regarding V02max(approximately 70 ml.kg-I.min-I and 5.01 I.min-I) or lean body weight. However, group I bicycled 40 km on the road 10% faster than group 2 (P < 0.05; 54 vs 60 min). Additionally, group I was able to generate II % more power during the I h performance test than group 2 (P< 0.05), and they averaged 90 :i: 1% V02maxcompared with 86 :i: 2% V02ma>in group 2 (P = 0.06). The higher performance power output of group I was produced primarily by generating higher peak torques about the center of the crank by applying larger vertical forces to the crank arm during the cycling downstroke. Compared with group 2, group I also produced higher p.eak torques and vertical forces during the downstroke even when cycling at the same absolute work rate as group 2. Factors possibly contributing to the ability of group I to produce higher "downstroke power" are a greater percentage of Type I muscle fibers (P < 0.05) and a 23% greater (P < 0.05) muscle capillary density compared with group 2. We have also observed a strong relationship between years of endurance training and percent Type I muscle fibers (r = 0.75; P < 0.001). It appears that "elitenational class" cyclists have the ability to generate higher "downstroke power", possibly as a result of muscular adaptations stimulated by more years of endurance training.
The entire manuscript can be downloaded here: http://www.edb.utexas.edu/coyle/publications.php. Choose article #40
COMMENT: This study is frequently referenced by PC naysayers as having "proved" that "just pushing harder" is better than trying to pedal in circles. It does no such thing. There are only really three things that can be taken from this study.
1. The faster cyclists put out more power than the lesser cyclists.
2. The faster cyclists had better aerodynamics/bike handling skills than the lesser cyclists.
3. The faster cyclists had much better aerobic backgrounds than the lesser cyclists.
4. Pushing harder had little to do with how fast one was. The fastest rider by far only had the 4th hardest push where the two riders with the hardest push were the 4th and 10th ranked riders in this group of 15 riders. Clearly, going fast involves a lot more than just pushing harder.
But, to go into more specifics:
First, Yes, there was a difference between how the two groups pedaled, with the faster group "pushing harder", and the lesser group "pulling up" more, but the pulling up difference did not reach statical significance. And, this difference was only present when riding at their maximum sustainable power. There was no difference in technique when riding at lower power. From page 101. Interestingly, the general pedaling technique of the cyclists in each group remained the same when the subject were all compared at the same power output (162 W for SLP) and at a cadence of 90 rpm (Fig. 7 and Table 7)." Even the "pushing harder" conclusion is slightly suspect since the authors (and all those who refer to this study to "prove" their point) fail to take into account the fact that downward forces during the pushing phase are a combination of both how hard the cyclists pushes and how heavy the leg is. Table 2 on page 97 shows the elite group had substantially more massive legs than the lesser group. Yet no attempt was made to account for this when analyzing how hard they were actually "pushing" - they simply assumed downward pedal force was equivalent to pushing. Further, no mention was made that this group also had to do more work on the backstroke to put more potential energy into the leg to simply unweight and raise it up to TDC. While it is probable that this group did push somewhat harder because they had more muscle mass to do so, it is also true they had to work harder on the backstroke (they essentially completely unweighted on the backstroke) such that the extra power they generated was probably balanced between both the "pushing" and "pulling" phase. This is what PowerCranks does, better balances these two phases of the bicycle stroke (and the top and the bottom also) such that these results actually support the PowerCranks position.
Second, there was a rational explanation to explain the "pulling up" difference. From page 105. "Data from our laboratory (Kautz et aI., submitted for publication) indicate that the torque production patterns exhibited by a cyclist were similar with increasing work rates, with the major difference at higher power outputs being increased peak torque during the downstroke and, to a much lesser extent, reduced negative torque during the upstroke." So, the Kautz data, shows that the closer one is to their maximum, the more they pull up on the backstroke. Even the elites do this. It is reasonable to conclude that the group 2 people were trying harder than the group 1 people since their pedaling patterns were essentially identical at lower power. It suggests that the differences that many think are so remarkable are not differences at all.
Third, the author writes this: "it is not surprising that a measure of effectiveness based solely on the orientation of the applied force fails to yield a meaningful measure of the true "effectiveness" of the movement. It is clear that any future research attempting to quantify effectiveness must consider more than the orientation of the applied pedal forces. This finding makes it unclear whether feedback devices that allow a cyclist to improve pedaling effectiveness (2,3,21) will lead to improved performance." According to the author, nothing can be concluded from this result as to whether feedback devices (such as PowerCranks), designed to improve pedaling effectiveness, will or will not lead to improved performance.
Fourth, the results of this study with regard to pedal forces goes against pretty much every study ever done before. From page 105. "Differences between the power output and pedaling cadence utilized in the present investigation and those used in previous studies (10,11,16,18,19,21,27) made it difficult to compare the present data with previous biomechanical data. This is especially so since none of the previous studies characterized competitive cyclists under conditions similar to those of the 1 h performance ride. A consistent conclusion of the previous studies was that cyclists did not pull up on the pedal during the upstroke. However, the present study found less negative torque during the upstroke than the previous studies. In some instances this reduction in negative torque was produced by pulling up on the pedal." It would mean more if one of the groups were shown to actually pedal as almost every study done to date has shown most cyclist pedal.
Fifth, only one side was analyzed for pedal forces. this presents the possibility if a rider has a right/left difference that the recorded data is not representative of what is actually going on.
Sixth, we don't know what the participants were told. If they were told the study would be looking at pedaling technique maybe the second group were more motivated to pedal as they thought the better athletes would pedal so they wouldn't look so bad, so they tried harder to "pull up" when the better people just rode as they normally do.
Seventh, as noted above, the elite group had substantially larger leg muscles with significantly more aerobic capacity than the lesser group. Is it surprising that they might have been able to "push harder" than the lesser cyclists?
Another study confirming that "pushing harder" is not necessarily the answer is the study done by Smak. Check it out.