was used during the first 5–6 s of the race. The
decrease in running speed over the 100 m com-
menced when the high-energy phosphate stores
were markedly reduced and glycolysis was the
predominant energy provider. Lactate did not
536 sport-specific nutrition
accumulate to a level which could have inhibited
glycolysis and is unlikely to have been the princi-
pal cause of fatigue. These results show that the
rate of PCr utilization is critical to running speed.
In agreement with these results, Locatelli and
Arsac (1995) showed that anaerobic glycolysis
provided approximately 65–70% of the meta-
bolic energy production during a 100-m race in
their study of four male and four female national
sprinters analysed during the 1994 Italian
championships.
The validity of postexercise lactate concentra-
tion as an indicator of the rate of anaerobic gly-
colysis was investigated in 400-m sprinting by
Lacouret al. (1990), and in 100-m and 200-m
sprinting by Hautier et al. (1994). In the study by
Lacouret al. (1990), blood samples were taken
Table 41.1Current world sprint records (as at January 1999).
Men Women
Distance (m) Time (s) Sprinter Time (s) Sprinter
100 9.84 D. Bailey 10.49 F. Griffith-Joiner
200 19.32 M. Johnson 21.34 F. Griffith-Joiner
400 43.29 H. Reynolds 47.6 M. Koch
Fig. 41.1Sprinters and hurdlers in training complete
prolonged sessions with many short efforts, even
though competitions may involve only a single sprint.
Photo courtesy of Ron Maughan.
50
40
30
20
10
0 20 40 60 80 100 120
10
7.5
5.0
2.5
0
Distance (m)
Phosphocreatine (mmol
.kg
–1
wt)
Speed (m
–1.s
)
Fig. 41.2Speed () and muscle phosphocreatine
concentration () during a simulated 100-m track
sprint (Hirvonen et al. 1987).