RT Journal Article
SR Electronic
T1 Diaphragm fatigue during exercise at high altitude: the role of hypoxia and workload
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP 674
OP 680
DO 10.1183/09031936.01.17406740
VO 17
IS 4
A1 M. Gudjonsdottir
A1 L. Appendini
A1 P. Baderna
A1 A. Purro
A1 A. Patessio
A1 G. Vilianis
A1 M. Pastorelli
A1 S.B. Sigurdsson
A1 C.F. Donner
YR 2001
UL http://erj.ersjournals.com/content/17/4/674.abstract
AB The effect of high altitude (HA) on exercise-induced diaphragm fatigue in normal subjects was examined.Eight normal subjects completed an incremental exercise test at sea level (SL) and at 3,325 m. Before (baseline), during, and after exercise (recovery), maximal transdiaphragm pressure (Pdi,sniff), breathing pattern, and diaphragmatic effort (PTPdi) were measured. Arterialized blood lactate was measured at baseline and during recovery.At maximal exercise (WRmax) Pdi,sniff fell to 72% and 61% of baseline at SL and HA respectively, recovering to baseline in 60 min at SL, and >60 min at HA. At the 5th min of recovery, circulating lactate was six-fold and seven-fold baseline at SL and HA, respectively. The time course of circulating lactate recovery was as for Pdi,sniff. At WRmax PTPdi was 80.74±9.87 kPa·s−1 at SL and 64.13±8.21 kPa·s−1 at HA. HA WRmax compared to isowork rate, SL data showed a lower Pdi,sniff (8.90±0.68 versus 11.24±0.59 kPa) and higher minute ventilation (117±11 versus 91±13 L·min−1), PTPdi being equal.To conclude, in normal subjects hypoxia-related effects, and not an increase in diaphragm work, hastens exercise-induced diaphragm fatigue and delays its recovery at high altitude compared to sea level.