As editors of a recently published supplement on football and
altitude1, which contains review papers based on presentations given by
experts in the field at a consensus meeting, we feel obliged to bring to
your attention a re-analysis of data published in the British Medical
Journal2. In this paper McSharry analyzed the results of the qualification
games for the world championships over the last 104 years in South America
and demonstrated in figure 2 that high altitude teams had an advantage
from playing at low altitude. This conclusion was questioned as being
inconsistent with the understanding of altitude physiology and physics
presented at the consensus meeting1, which promoted McSharry to re-analyze
the data with a non-linear model. The result of this re-analysis, which is
shown in figure 1 of the paper of Gore et al.3 published in the
supplement, indicates that when two teams are from the same altitude, the
probability of the home team winning was 0.50, but this increased to 0.57
if a team from an altitude of 3600 m played at home against a team from
sea level. However, the probability of a home win even rose to 0.73 for a
team from sea level at home against a team from 3600 m.
These discrepant outcomes of modelling the same data set demonstrate
that the outcome of such analysis depends very much on the model that is
used and possibly also on additional assumptions or corrections that are
made.
Peter Bärtsch, Dept. of Internal Medicine, Div. of Sports Medicine,
Medical University Clinic, Heidelberg, Germany peter.bartsch@med.uni-heidelberg.de
Jiri Dvorak, Dept. of Neurology/Neurophysiology, Schulthess-Clinic,
Zurich, Switzerland
Bengt Saltin, Copenhagen Muscle Research Centre (CMRC), University
Hospital, Copenhagen, Denmark
Competing interests: None declared
1. Bärtsch P, Dvorak J, Saltin B. Special Issue: Football and
Altitude. Scand J Med Sci Sports 2008; 18(Suppl.1):1-99.
2. McSharry PE. Effect of altitude on physiological performance: a
statistical analysis using results of international football games. BMJ
2007; 335:1278-81.
3. Gore CJ, McSharry PE, Hewitt AJ, Saunders PU. Preparation for
football competition at moderate to high altitude. Scand J Med Sci Sports
2008; 18(Suppl 1):85-95.
Competing interests:
None declared
Competing interests:
No competing interests
19 November 2008
Peter Bärtsch
Prof. of Sports Medicine, Head of Div. of Sports Medicine
Jiri Dvorak, and Bengt Saltin
Medical University Clinic, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
Rapid Response:
Effect of altitude on football performance
Sir,
As editors of a recently published supplement on football and
altitude1, which contains review papers based on presentations given by
experts in the field at a consensus meeting, we feel obliged to bring to
your attention a re-analysis of data published in the British Medical
Journal2. In this paper McSharry analyzed the results of the qualification
games for the world championships over the last 104 years in South America
and demonstrated in figure 2 that high altitude teams had an advantage
from playing at low altitude. This conclusion was questioned as being
inconsistent with the understanding of altitude physiology and physics
presented at the consensus meeting1, which promoted McSharry to re-analyze
the data with a non-linear model. The result of this re-analysis, which is
shown in figure 1 of the paper of Gore et al.3 published in the
supplement, indicates that when two teams are from the same altitude, the
probability of the home team winning was 0.50, but this increased to 0.57
if a team from an altitude of 3600 m played at home against a team from
sea level. However, the probability of a home win even rose to 0.73 for a
team from sea level at home against a team from 3600 m.
These discrepant outcomes of modelling the same data set demonstrate
that the outcome of such analysis depends very much on the model that is
used and possibly also on additional assumptions or corrections that are
made.
Peter Bärtsch, Dept. of Internal Medicine, Div. of Sports Medicine,
Medical University Clinic, Heidelberg, Germany
peter.bartsch@med.uni-heidelberg.de
Jiri Dvorak, Dept. of Neurology/Neurophysiology, Schulthess-Clinic,
Zurich, Switzerland
Bengt Saltin, Copenhagen Muscle Research Centre (CMRC), University
Hospital, Copenhagen, Denmark
Competing interests: None declared
1. Bärtsch P, Dvorak J, Saltin B. Special Issue: Football and
Altitude. Scand J Med Sci Sports 2008; 18(Suppl.1):1-99.
2. McSharry PE. Effect of altitude on physiological performance: a
statistical analysis using results of international football games. BMJ
2007; 335:1278-81.
3. Gore CJ, McSharry PE, Hewitt AJ, Saunders PU. Preparation for
football competition at moderate to high altitude. Scand J Med Sci Sports
2008; 18(Suppl 1):85-95.
Competing interests:
None declared
Competing interests: No competing interests