oxygen uptake and, in these cases, the attainable
level can vary considerably between individuals.
4 The technique has to be learned.
5 The duration of races may be such that the
glycogen stores become emptied.
6 The training necessary to obtain the perfor-
mance level of elite competitors is such that only
an extremely well-trained individual can endure
this.
As a consequence of these characteristics, the
training should contain practices that: (i) chal-
lenge the cardiovascular system considerably, (ii)
activate all of the muscles used during compet-
etive skiing, (iii) improve the technical skill, and
(iv) last for periods of up to several hours.
Moreover, the amount of training should be
increased gradually during the course of each
year and from one year to the next. Otherwise,
there is a considerable risk of overtraining and
overuse injuries.
Running and roller-skiing can elicit approxi-
mately the same oxygen uptake as that achieved
in all-out skiing (Bergh 1982). Ski-walking
(walking up a steep hill using poles to imitate
skiing) and cross-country skiing have been
found to produce slightly higher levels of oxygen
uptake than running in individuals trained for
cross-country skiing (Hermansen 1973; Stromme
et al.1977). Roller-skiing has an advantage over
running in regard to training of the upper body:
the activity patterns of the muscles are similar in
skiing on snow and roller-skiing. This is advanta-
geous for the development of the local aerobic
power. This is important because the muscles
involved in poling must have endurance since
this activity contributes significantly to perfor-
mance in skiing. Moreover, it has been demon-
strated that individuals who can attain a
relatively high oxygen uptake during upper-
body exercise benefit in regard to the maximum
oxygen uptake that can be attained during com-
bined arm and leg exercise (Bergh et al.1976).
Elite skiers rarely use barbells or other resist-
ance devices in order to improve maximum
muscle strength. However, repeated double-
poling on roller-skis at maximal speed for 10–30 s
is used as strength training. This exercise is a
minor part of the training (3–5% of the time
during summer and early fall).
Skiing technique should be learned by skiing,
because other exercises, e.g. roller-skiing and
ski-walking, do not display the same muscular
activity patterns as in skiing, judging from
electromyographic recordings. In general, it is
preferable to concentrate on technique with
youngsters because they learn more easily than
adults. In total, elite male and female skiers train
about 650–750 and 500–700 h · year–1, respec-
tively. In addition, they normally compete in
about 35–45 ski races · year–1.Metabolic energy yield
In order to evaluate the average metabolic
energy yield during a ski race, heart-rate record-
ings during the race and blood lactate and core
temperature measurements after the race have
been used. Using these measures, it can be esti-
mated that the average energy expenditure
during ski racing between 5 and 30 km is in the
range of 90–95% of maximum oxygen uptake.
During the longer ski races, it is some 5–10%
lower. There are no reasons to believe that
genders differ in this respect.
Combining this information on fractional
utilization of oxygen with data on maximum
oxygen uptake of elite skiers, racing metabolic
cost can be estimated. Such calculations indicate
that the metabolic rate of an average male elite
skier is about 1.5–2 kW during the shorter races.
During longer races (50 km and longer), the
metabolic rate is about 10% lower. The total
energy yield for a normal 15-km race is about
4–5 MJ (950–1200 kcal) and for a 50-km race about
13–15 MJ (3100–3600 kcal). Corresponding calcu-
lations for females indicate that they use about
30% less energy than males for a given distance,
which is due to the lower maximum aerobic
power and body mass in the females.Heat balance
Since cross-country skiing is often performed in
cold climates, problems related to cold injuries,