negatively correlated with Sao2. Conclusion: The increase in plasma levels of ATI, AT, and
insulin may be involved in the pathogeneses of high altitude diseases.
26.
EFFECTS OF THE « LIVING HIGH-TRAINING LOW » METHOD ON PERFORMANCE
AND THE AUTONOMIC CONTROL OF THE CARDIOVASCULAR SYSTEM IN HIGHLY-
TRAINED SWIMMERS. JEREMY CORNOLO
1
JEAN-PIERRE FOUILLOT
1
LAURENT
SCHMITT
2
PAUL ROBACH
3
, GREGOIRE MILLET
4
, JEAN-PAUL RICHALET
1
. EA2363,
ARPE, Université Paris 13, Bobigny, France
1
CNSN, ID Jacobeys, 39200 Prémanon
2
ENSA,
74401 Chamonix
3
, EA 3759, Faculté des Sciences du Sport, 34090 Montpellier
4
.
We investigated whether training-induced decreased sympathetic and increased cardiac
parasympathetic drive may be limited by autonomic adaptations to intermittent hypoxia. Eighteen
national swimmers were assigned to a live low-train low (LL-TL; natural altitude 1100m) or a
live high-train low (LH-TL; 16h/day at simulated altitude 2,500-3,000m) group. Subjects were
investigated at 1100m before (PRE), after (POST1) and 15 days after (POST2) a 13-day training-
camp. During a tilt test (supine-60°): blood pressure (BP), total peripheral resistances (TPR) and
autonomic control of the cardiovascular system assessed by HR and BP variability were obtained.
Total hemoglobin (nHb) was calculated from hemoglobin and hematocrit. Maximal oxygen
uptake (VO2max) and 2000m performance were recorded during swimming trials. Responses to
tilt test were similar at PRE, POST1 and POST2. The change in VO2max (POST1-PRE) tended
to be higher in LH-TL than in LL-TL (P=0.08). LL-TL improved 2000m performance (+1.6%).
LL-TL decreased resting HR (-9%) and RR-LFnu (P=0.02) while LH-TL tended to(HR, -5%;
RR-LFnu, P=0.06). LH-TL presented higher TPR (P=0.02), BP-LFnu (P=0.02) and BP-LF/HF
(P=0.01) than LL-TL. LHTL seems to increase nHb compare to LL-TL (P=0.08). Orthostatic
intolerance was observed at POST1 (LL-TL, n=3 ; LH-TL, n=2). At POST2, VO2max shifted
towards PRE in LH-TL (POST2 vs POST1, P=0.06). Resting HR decreased not significantly in
LH-TL (POST2 vs POST1; -6%). HR and RR-LFnu became lower than PRE in both groups.
MBP decreased in both groups at POST2 vs POST1. Conclusion: Intermittent hypoxia: 1) had no
major limiting effects on the training-induced cardiovascular adaptations, 2) might favour the
improvement of VO2max by an increase in nHb while residual effects of hypoxia may be
progressively reversed in normoxia, 3) did not induce an impairment of autonomic balance.
27.
AUTONOMIC CONTROL OF THE CARDIOVASCULAR SYSTEM DURING
ACCLIMATIZATION TO HIGH ALTITUDE: EFFECTS OF SILDENAFIL. JEREMY
CORNOLO
1
PASCAL MOLLARD
1
JULIEN BRUGNIAUX
1
PAUL ROBACH
2
JEAN-PAUL
RICHALET1. EA 2363, ARPE, Université Paris 13, Bobigny, France
1
ENSA 74401 Chamonix,
France
2
.
Objective: Both acute hypoxia and sildenafil may influence autonomic control through
transient cardiovascular effects. In a double-blind study, we investigated whether sildenalfil could
interfere with cardiovascular effects of hypoxia. Methods: Twelve healthy men (placebo, PLA n
= 6; sildenalfil, SIL n = 6) were exposed to 4,350m during six days. Treatment was continuously
administered from 6-8 hours after arrival at altitude (3x40mg/day). The autonomic control on the
heart was assessed by heart rate variability (HRV) during sleep at sea level (SL), between days 1-
2 (D1-2) and days 5-6 (D5-6) in hypoxia. Arterial pressure (AP) and total peripheral resistances
(TPR) were obtained during daytime. Results:There were no statistical differences between
groups in HRV, AP, and TPR throughout the study. Hypoxia induced a decrease in R-R interval
and an increase in AP in both groups. Low frequency/high frequency ratio increased at D1-2
(PLA, P = 0.04; SIL, P = 0.02) and D5-6 (PLA and SIL, P = 0.04) versus SL, while normalized
high frequency power decreased only in PLA (P = 0.04, D1-2 vs SL). Normalized low frequency
power increased at high altitude (PLA and SIL, P = 0.04, D5-6 vs SL). TPR decreased at D2 in
PLA (P = 0.02) and tended to normalize at D6 (P = 0.07, D6 vs D2). Conclusion: Acute hypoxia
