1) Sixteen elite swimmers lived and trained for 3 weeks at an altitude of 2320 meters. All subjects experienced symptoms of acute mountain sickness (AMS) with the highest scores on the first day and lowest on the seventh day. 2) Heart rate and some heart rate variability measures showed differences throughout the first week, with maximum heart rate values on the third day and decreases in relaxation index and total power up to the third day. 3) While the worst results for AMS were on the first day and for cardiovascular variables on the third day, there was not a strong correlation between AMS symptoms and heart rate variability measures. However, heart rate was higher in swimmers experiencing moderate to severe AMS symptoms.

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2. HEART RATE VARIABILITY AND ACUTE MOUNTAIN SICKNESS
DURING THE ACCLIMATIZATION PERIOD OF ALTITUDE
TRAINING CAMP IN ELITE SWIMMERS
C Calderón-Soto1, AJ Morales3, FA Rodríguez2, X Iglesias2, B Feriche3, J Vázquez2, L Rodríguez-Zamora2, A Barrero2, E
Hynynen4.
1: CAR Sierra Nevada, Granada (Spain), 2: INEFC, University of Barcelona (Spain), 3: FCAFD, University of Granada (Spain), 4: KIHU
Research Institute for Olympic Sports, Jyväskylä (Finland).
Objetive
During altitude training hypoxic stimulus may lead to symptoms of acute mountain sickness and changes in autonomic
balance measured by heart rate variability. Our aim was to analyze the classical parameters and the new ones
developed by Firstbeat Technologies during the acclimatization period at moderate altitude.
Methods Results
16 elite swimmers lived and trained 3 weeks at 2320 m All subjects experienced AMS symptoms with a
in the Altitude Training Center of Sierra Nevada, Spain. medium score of 2.7 ± 2.3. Highest score was on day-1
(3.8 ± 2.6) while lowest was on 7th (1.1 ± 1.1).
22.2 ± 1.6 74.8 ± 7.9 186.2 ± 8.8
years kg cm Mean heart rate showed differences throughout the
week (p<0.05) with maximum values on day-3.
RR-intervals were recorded every morning in supine
position (8-min) with beat-by-beat heart rate monitors at
paced breathing (12/min). Data were analyzed with
Firstbeat Health software using neural network model.
Absolute relaxation index and total power decreased up
to day 3 while no significance difference was found in
RMSSD, LF/HFratio, HF normalized and LF normalized.
Acute mountain sickness (AMS) was scored with Lake
Louise questionnaire.
Check mark þ if you felt (or not) any of these symptoms last night or today
0 1 2 3
g g g g
Headache No headache Mild headache Moderate headache Severe headache,
incapacitating
c c c c
Gastrointestinal symptoms None, Poor appetite Moderate nausea Severe nausea
normal appetite or mild nausea and/or vomiting and/or vomiting
g g g g
Fatigue and/or weakness Not tired or weak Mild Moderate Severe
fatigue / weakness fatigue / weakness fatigue / weakness
c c c c
Dizziness / lightheadedness Not dizzy Mild Moderate Severe dizziness,
dizziness dizziness incapacitating
g g g g
Difficulty sleeping Slept as well as usual Did not sleep Woke many times, Could not sleep at all
as well as usual poor sleep
Pre-altitude values and on days 1, 3, 5 and 7 were
analyzed for mean heart rate, absolute relaxation index,
RMSDD, total power, LF/HFratio, and HF and LF
normalized.
As worst results for AMS were on day-1 AMS and for
cardiovascular variables on day-3, there was not a
good correlation. Nevertheless HR was higher in
swimmers who experienced moderate or severe
symptoms vs no/light (63.4 vs 58.0 bpm).
Conclusions
Clinical and physiological states during altitude training could be monitored by heart rate variability and symptomatology.
Although there is great variability among subjects, new variables as absolute relaxation index show potential usefulness during
the acclimatization period of altitude training. Clinical and cardiovascular variables show some delay but both seem to recover
at the end of the 1st week. More studies are needed to control other variables such as training load and individual susceptibility.
References
-Aubert A et al (2003). Heart rate variability in athletes. Sports Med 33:889.
-Schmitt L et al (2006): Heart rate variability and performance at two different altitudes in well-trained swimmers. Int J Sports Med 27:226.
-Heart beat based recovery analysis for athletic training. White paper by Firstbeat Technologies Ltd, 2009.
Correspondence:
Dra Carmen Calderón. Sport Medicine Department. CAR Sierra Nevada. Spain.
carmen.calderon@csd.gob.es