I downloaded the same paper over the weekend. The download conditions prohibit reproducing the document. However, I don’t think there is a problem with openly discussing the findings of the study in general terms, most of which are stated in the abstract, which is freely and publicly available here. The researchers concluded:

--Running involves both external work ( W_ext, which consists of forward speed changes and vertical displacement of the center of gravity in each stride) and internal work (W_int, which is due to movement of the body that does not directly result in forward or vertical propulsion....specifically, arm and leg swings).

--Total work performed while running is the sum of external and internal work….W_tot = W_ext + W_int.

--From the abstract, "The external work performed per kilometer is independent of speed, amounting to 0.25 kcal/kg/km. Total mechanical work amounts to about 0.40-0.50 kcal/kg/km." Thus, external and internal work are about equal.

Neither the abstract nor the detailed report explicitly state that W_int is independent of speed, as they do in the case of W_ext. However, it is implied in the conclusion that total work (W_tot) is relatively constant at 0.4-0.5 kcal/kg/km at all speeds. Note the second paragraph in the section titled "Total mechanical work and efficiency" on the sixth page of the paper (journal page 254).

This paper indicates that the amount of work performed while running, which was my meaning of the term “workload”, is a function of distance covered and is independent of speed. It supports my previously stated opinion that a person running 5x1100m in 3-minute repeats performs more work than does one running 5x800 repeats in 3-minute intervals.

However, a second research project and paper, “Mechanical work and efficiency in level walking and running”, by the same primary researcher, Cavagna, 12 years later (1976) updates and supersedes the findings of the 1964 paper. This paper is freely and publicly available in its entirety here. The paper alters some of the findings of the 1964 study:

--W_ext was found to be independent of speed, as in the 1964 study. (Actually, it was found to decrease slightly with speed, but not appreciably.)

--However, unlike in the 1964 study, W_int and, as a result, W_tot were found to increase with speed. Specifically, the paper says, ”From the few data obtained by Cavagna et al. (1964) the work done per unit distance in running appeared to be independent of speed: the present more numerous and precise data leave little doubt that it increases with speed.” (See page 9 of the report….journal page 476.)

--The paper presents an equation defining W_totdot as a function of speed….W_totdot = 9.42 + 4.73V_f + 0.266V_f^1.993, where W_totdot is work/unit of time (cal/kg/min) and V_f is forward velocity in km/hour.

Figure 3 on the eighth report page (journal page 475) charts W_ext, W_int, and W_tot for speeds from 3 km/hour to 33 km/hour. The curves indicate that W_ext and W_int are equal at 20 km/hour. At slower speeds, W_ext is greater than W_int and at faster speeds the opposite is the case.

The figure indicates that the increase in W_tot, although linear as speed increases, does not increase at the same rate as does speed. Tripling speed from 10 to 30 km/hour, results in increasing W_tot by about 50% from 0.5 kcal/kg/km to 0.75 kcal/kg/km. In practical terms, that would indicate that a 4:15-minute miler with a body mass of 65kg would perform 46.5 kcal of work while running an 1100m VO2max repeat in 3-minutes (0.65 kcal/kg/km x 65kg x 1.1km). To perform the same amount of work, a 6-minute miler with the same body mass of 65kg would have to run 1300m, which would take him about 4:50 at his VO2max pace. OTOH, if the 6-minute miler runs a 3-minute, 800m VO2max repeat, he would perform 28.6 kcal of work, or about 62% of the amount of work performed by the faster runner, which is somewhere between the positions that we were taking last week.

However, I still agree that workload and training load (stimuli) are different. The faster runner can probably handle….even needs….a higher workload for the same relative training benefit.