european college of sport science

LACTATE IN WHOLE BODY EXERCISE; AN ANAEROBIC END PRODUCT AND AN AEROBIC SUBSTRATE
VAN HALL, G.
RIGSHOSPITALET
IS-PH03 Cross-Country skiing
Lactate in whole body exercise; an anaerobic end product and an aerobic substrate
G van Hall
Department of Biomedical Sciences, University of Copenhagen & Metabolic Mass-Spectrometry Facility, Rigshospitalet, Copenhagen,
Denmark
Lactate has been considered a dead end waste product of glycolysis due to hypoxia and a major cause of fatigue. The produced lactate
thought to be cleared by the liver for gluconeogenesis. However, it has become clear that skeletal muscle continuously produces lactate,
and during exercise without an apparent lack of oxygen. The increase of lactate production with exercise is depending on the acceleration
of glycolysis causing and increase in pyruvate and NADH concentration that will shift the equilibrium enzyme lactate dehydrogenase
to lactate formation. Moreover, during exercise the active muscles are by far the most important tissue for lactate uptake and subsequent
oxidation. Thus, the muscle net lactate release, and to a large extent the systemic lactate concentration, is depending on the balance
between the active muscle lactate production and simultaneous utilization. This concept becomes very clear during diagonal stride rollerskiing
at about 75% VO2max (van Hall et al., 2003). A relative small increase in arterial lactate (~2.5 mmol/L) occurs despite a very high
whole body lactate production (~14.1 mmol/min) caused by the large release of lactate by the arms and legs. However, the legs are
taking up and oxidizing substantially more lactate than they produce. Thus, due to the large leg muscle mass and energy requirements
for contraction the legs are able to clear and oxidize most of the lactate that is produced during diagonal stride roller skiing keeping
systemic lactate concentrations low. In addition, the arms showed to be equally efficient in lactate utilization per kg of muscle than the
legs, however, the arms produced far more lactate than they consumed, i.e. are more glycolytic than legs. These findings imply that
systemic lactate levels are no measure for aerobic/anaerobic capacity of athletes in different sport disciplines. Moreover, sports that use
both the arms and the legs like rowing, swimming and cross-country skiing the lactate levels will depend on the relative utilization of
arms versus legs. This implies that blood lactate levels cannot be used to evaluate training status or technique (Mittelstadt et al., 1995;
Larson, 2006).
References
Van Hall G et al. Leg and arm lactate and substrate kinetics during exercise. Am J Physiol Endocrinol Metab 284: E193-E205, 2003.
Larson AJ. Variation in heart rate and blood lactate threshold due to exercise model in elite cross-county skiers. J Strength Cond Res
20:855, 2006.
Mittelstadt SW et al. Lactate response to uphill roller skiing: diagonal stride versus double pole technique. Med Sci Sport Exerc 27: 1563,
1995.
SPRINT COMPETITIONS AND MAXIMAL SPEED IN CROSS-COUNTRY SKIING - A PHYSIOBIOMECHANICAL UPDATE.
STÖGGL, T., MÜLLER, E., HOLMBERG, H.C.
UNIVERSITY OF SALZBURG, MIDSWEDEN UNIVERSITY
Due to the recent introduction of sprint races and an increasing number of mass start competitions in the World Cup series, new aspects
of training and testing are becoming fields of research. This could be attributed to the upcoming specialization of athletes in sprint racing,
as well as to the technical modifications demonstrated for selected techniques, eg. double poling (Holmberg et al. 2005) and doublepush
skating (Stöggl et al. 2008a). Both technical modifications were found to be superior to the conventional skiing style. In addition, the
mean skiing velocity in WC sprint races has shown a steady increase in skiing speed (Stöggl et al. 2008b), reaching mean race speeds of
up to 9.5m/s in classical style and up to 10m/s in skating. It should be noted that skiing speeds in the majority of scientific studies are
quite apart to these values. It was demonstrated that there is a moderate to high correlation between sprint performance and performance
in distance races (Stöggl et al. 2008b).
It was recently shown that short duration maximal skiing speed and specific maximal and explosive strength are good predictors of
cross-country skiing sprint performance (Stöggl et al. 2007a,b 2009). Interestingly it was found that skiers with higher maximal power
output and maximal skiing speeds showed, in addition to their higher performance, less fatigue during all-out tests of the same duration
as a sprint race. These results may be coupled to the prerequisites of modern sprint techniques, as characterized by high peak forces
and high force impulses over a short time. The combination of high force output over a short time and thus a longer recovery time was
found to be faster and more economical (Holmberg et al. 2005; Stöggl&Müller 2009). Furthermore, it was found that cycle length but not
cycle rate was related to performance, especially at submaximal velocities. This was particularly true of the V2 technique and diagonal
stride, whereas in double-poling there seems to be an optimum cycle length and cycle rate pattern (Stöggl&Müller 2009). Measures of
aerobic capacity (VO2max) showed only low correlations to sprint performance. However, it should be noted that a high level of VO2max
should be the basis but also that other factors that are mainly associated with neuromuscular factors and anaerobic capacity discriminate
between weak and strong sprint skiers.
These findings should lead to a reconsideration of concepts in the training and testing of cross-country skiers. In addition to common
VO2max and incremental step tests, also strength and speed tests should be included. Maximal and explosive strength training sessions
could also be useful additions to conventional aerobic and strength endurance training.
References
Holmberg et al (2005). Med Sci Sports Exerc. 37:807-818.
Stöggl et al. (2007) Scand J Med Sci Sports. 17:362-372.
Stöggl et al (2007) Med Sci Sports Exerc. 39:1160-1169.
Stöggl et al (2008) JSports Sci. 26:1225-1233.
Stöggl et al (2008) Competition analysis. ICSS4 657-677.
Stöggl & Müller (2009). Med Sci Sports Exerc. press.
270 14 TH
ANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCE