exercise will also enhance performance. The
mechanism is not clear but it is most likely
that the glucose uptake from the bloodstream
may contribute considerably to the aerobic
metabolism.
Therefore, most skiers consume some 100–
200 ml of a 5–10% carbohydrate drink about each
10–15 min in races with a duration longer than 1
h. The intake is of the same order of magnitude as
the minimum of 40–60 g · h–1suggested by Coyle
(1991). However, some skiers also take in a solu-
tion with up to 25–30% of carbohydrates. The
reason for this is that the net uptake of glucose is
higher in such a solution than with a traditional
5–8% concentration, although the water uptake
is, of course, less.
During training camps at altitude, the water
turnover is increased because of the increased
urine output and the high respiratory water
losses. Some elite skiers drink up to 8–10 l · day–1
in order to compensate for the increased rate of
dehydration during altitude training.
Vitamins and minerals
Vitamins and minerals are essential nutrients for
optimal performance. It is well known that defi-
ciencies impair general health and human func-
tions but, in present-day society, obvious vitamin
deficiencies are rare. Cross-country skiers have a
high energy intake. Since the amount of nutrient
intake mainly follows energy intake when the
athlete consumes ‘normal’ food (Blixt 1965),
there is a general agreement that the risk of an
inadequate nutrient intake is low in athletes with
high total energy intakes.
Conclusion
Cross-country skiing is dynamic exercise involv-
ing a large muscle mass. There are many different
skiing techniques. The energy yield is mainly
aerobic and the cardiovascular system can be
taxed maximally during skiing. Therefore, cross-
country skiing is effective in regard to endurance
training. The elite skier is characterized by an
extremely high maximum oxygen uptake and
the skeletal muscles contain predominantly
slow-twitch fibres. Body size is not very different
from the average person of corresponding
gender and age. Training is mainly performed by
skiing, roller-skiing and running. The energy
demand is very high, and in longer races, the
glycogen stores may be emptied. Proper rehy-
dration procedures during races are of greatest
importance.References
Åstrand, P.O. (1955) New records in human power.
Nature 176 , 922–923.
Bergh, U. (1982) Physiology of Cross-Country Ski Racing.
Human Kinetics, Champaign, IL.
Bergh, U. (1987) The influence of body mass in cross-
country skiing. Medicine and Science in Sports and
Exercise 19 , 324–331.
Bergh, U. & Forsberg, A. (1991) Cross-country ski
racing. In Endurance in Sports(ed. R. Shephard & P.O.
Åstrand), pp. 570–581. Blackwell Science, Oxford.
Bergh, U. & Forsberg, A. (1992) Influence of body mass
on cross-country ski racing performance. Medicine
and Science in Sports and Exercise 24 , 1033–1039.
Bergh, U., Kanstrup-Jensen, I.-L. & Ekblom, B. (1976)
Maximal oxygen uptake during exercise with
various combinations of arm and leg work. Journal of
Applied Physiology 41 , 191–196.
Blixt, G. (1965) A study on the relation between total
calories and single nutrients in Swedish food. Acta
Sociologica et Medica Upsallieusis 70 , 117–125.
Coyle, E.F. (1991) Carbohydrate feedings: effects on
metabolism, performance and recovery. In Advances
in Nutrition and Top Sport(ed. F. Brouns), pp. 1–4.
Medicine and Sports Science No. 32. Karger,
Basels.
Ekblom, B. & Hermansen, L. (1968) Cardiac output in
athletes.Journal of Applied Physiology 25 , 619–625.
Hanson, J. (1973) Maximal exercise performance in
members of the US nordic ski team. Journal of Applied
Physiology 35 , 592–595.
Hermansen, L. (1973) Oxygen transport during exer-
cise in human subjects. Acta Physiologica Scandinavica
Suppl. 339, 1–104.
Ingjer, F. (1991) Maximal oxygen uptake as a predictor
of performance in women and men elite cross-
country skiers. Scandinavian Journal of Medicine and
Science in Sports 1 , 25–30.
Rusko, H. (1976) Physical performance characteristics in
Finnish athletes. Studies in Sports, Physical Education
and Health Vol. 8. University of Jyvèskylè, Jyvèskylè,
Finland.