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IMPLICATIONS OF RESEARCH ON RUNNING ECONOMY

Most of the early physiological research into the effects of running training focused almost exclusively on the effects of training on the athlete’s V02max. Yet we now know that the V02max of a healthy individual is relatively sExercises and changes relatively little, even with very intensive training (J. Daniels, 1974a; J. Daniels et al, 1978a; Svedenhag & Sjodin, 1985). Thus we may ask, Why does running performance continue to improve with training if the V02max does not increase in parallel?

One proven explanation is that training increases the running speed at the lactate tumpoint and that this change correlates closely with actual changes in running performance (Tanaka et al, 1984). Another important possibility is that an athlete who trains heavily shows a gradual and progressive increase in running efficiency, which continues to improve even for some years after the athlete’s V02max has reached its highest possible value (Svedenhag & Sjodin, 1985).

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Other findings are in accord with this interpretation. Scrimgeour et al. (1986) studied three groups of ultramarathon runners who trained at different weekly distances; the researchers found that the group of runners who trained the most (more than 100 km/week) differed only from the other groups in that they had superior running economy. The groups did not differ in their V02max values or in the percent V02max values that they sustained during races of 10 to 90 km.

In fact, the least-trained runners ran at significantly higher percent V02max values during the 10-km race than did the runners who trained the most. Others have also noted that weekly training distance does not predict the percent V02max that an athlete can sustain during competition, thus elite runners do not necessarily run at higher percent V02max values during competition than do nonelite runners (C.T.M. Davies & Thompson, 1979; Maughan & Leiper, 1983; Sjodin & Svedenhag, 1985; Svedenhag & Sjodin, 1985; Wells etal, 1981; C. Williams & Nute, 1983). In the studies of Scrimgeour et al. (1986) and Sjodin and Svedenhag (1985), the runners who trained the most also ran the fastest but only because they were more efficient. Thus, at the same percent V02max, the most-trained runners ran faster because they required less oxygen to run at any particular speed.

In summary, Scrimgeour et al. (1986) found that training more than 60 to 100 km/week did not increase the intensity of effort, measured as the percent V02max, that athletes could sustain during marathon and ultramarathon races. However, the more heavily trained runners were more efficient. Thus, it seems that their extra training increased their running efficiencies so that for the same effort during competition, the more trained runners ran faster. Sjodin and Svedenhag (1985) reported essentially the same finding except that they concluded that the cutoff training distance was 120 km/week. Together these studies suggest that the sole benefit of a very high weekly training distance may be a progressive increase in running efficiency. In view of the risks associated with heavy weekly training distances (see post 10), we may ask, Are there better and less risky ways of improving running economy?

Unfortunately, at present our understanding of all the factors that determine running economy is incomplete; we do not know how these factors might be altered most effectively. The evidence presented so far does suggest that in order to optimize running economy, the runner needs to pay greater attention to the following: minimizing the weight of shoes and clothing worn during competition; developing a long stride length with a slow stride frequency; and minimizing the weight of the moving limbs, in particular the legs, in much the way that cyclists strive to keep the weight of their revolving wheels to a minimum. In addition, runners need to be more aware of their aerodynamic profiles. Thus Kyle (1986) suggested that runners who run with tightly fitting clothing, with short hair, and without socks can reduce aerodynamic drag 2 to 6%. This change would be the equivalent of running 4 inches less in the 100-m race and 30 m less in a standard marathon.

In the future we can expect major efforts by running shoe manufacturers to increase the contributions of their products to running efficiency; by the bioengineers to understand intrinsic anatomical factors that influence running efficiency; and by coaches to develop new training techniques to improve the running efficiencies of athletes. Even the psychologist may have a role, given the finding that hypnosis can influence running efficiency (Benson et al, 1978). One shoe manufacturer is already studying the possibility of “tuning” running shoes so that a maximum amount of energy is returned to the foot with each stride (Kyle, 1986), in much the same way that running tracks have been “tuned” in order to allow faster running times (see post 11).

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