Abstract
The triathlon has come to be recognized as a distinct endurance event and although
a substantial body of research information exists with regard to the individual components
(canoeing, cycling, running, etc.), the physiologic demands imposed by combining the
respective activities into one continuous event have not yet been assessed.
Twenty-three male athletes (age = 33 ± 5.2 yr; mass = 71.79 ± 7.42 kg; height = 176.0
± 7.21 cm; X̄ ± SD) participated in the study on the basis of informed consent. Venous
blood samples, taken immediately prior to and on completion of the Iron Man Triathlon
held in Johannesburg during 1983, were assayed for parameters of energy metabolism,
fluid and electrolyte balance, and stress (tissue enzymes in serum). On the basis
of post-race blood glucose (6.17 mmol, ℓ-1), free fatty acids (1943 µmol. ℓ-1), and blood lactate (3.45 mmol. ℓ-1) changes, it was concluded that the triathlon is primarily, in an overall sense,
an aerobic event. With the exception of magnesium and iron, serum electrolyte changes
agreed with literature findings. However, body mass reductions (average 3.23 kg, i.e.,
4.5%) indicated that the extent of dehydration is more severe in the triathlon than
in comparable endurance events. Post-race enzyme levels (LD, CK, and AST) were significantly
elevated, and LD negatively correlated with total performance time (P < 0.01). The general conclusion is that the physiologic demand of the triathlon exceeds
that of other comparable endurance events.
Key words
exercise - metabolism - serum electrolytes - serum enzymes - hormones
