PMID- 11417436
OWN - NLM
STAT- MEDLINE
DCOM- 20011204
LR  - 20061115
IS  - 1439-6319 (Print)
IS  - 1439-6319 (Linking)
VI  - 84
IP  - 5
DP  - 2001 May
TI  - The reproducibility of tolerance to lower-body negative pressure and its 
      quantification.
PG  - 462-8
AB  - The reproducibility of tolerance to lower-body negative pressure (LBNP) has not 
      been assessed sufficiently. Furthermore, there has been confusion concerning the 
      most appropriate index by which LBNP tolerance can be quantified. The purpose of 
      this study was to assess the degree of reproducibility in 
      presyncopal-symptom-limited LBNP (LBNPtol), using an LBNP chamber. Twenty 
      physically active subjects [median age (range) 21 (18-27) years] underwent three 
      successive LBNPtol tests with 72-120 h between each test. LBNPtol was quantified 
      using the LBNP tolerance index (LTI; delta mmHg.min), cumulative stress index 
      (CSI; mmHg.min), duration of negative pressure (DNP) and maximum magnitude of 
      negative pressure (MNP). Heart rate (fc), systolic (SBP) and diastolic (DBP) 
      blood pressures from the three repeated tests were compared during a control 
      period. The changes from control to maximum response (fc, SBP, DBP) during LBNP 
      were also compared, and percentage changes in estimated blood volume were 
      measured. There were no statistical differences between any of these comparisons 
      (P > 0.05). LTI and CSI were greater in the third test when compared to the first 
      two tests (P < 0.05). The values for DNP and MNP were not statistically different 
      between tests (P > 0.05). Measures of LTI and CSI showed an acceptable level of 
      reproducibility for the first two repeated tests. However, there was an increase 
      in LBNPtol on the third successive exposure to LBNP. These findings have shown 
      that it is possible to achieve reproducible measures of tolerance to LBNP when 
      using a custom-built chamber. This only applies to a test-retest procedure. 
      Furthermore, these data also suggest that DNP and MNP do not adequately reflect 
      the differences shown in LBNP tolerance when using LTI and CSI as measures.
FAU - Howden, R
AU  - Howden R
AD  - Physiology of Exercise, De Montfort University, Lansdowne Road, Bedford, MK40 
      2BZ, UK. rhowden@dmu.ac.uk
FAU - Tranfield, P A
AU  - Tranfield PA
FAU - Lightfoot, J T
AU  - Lightfoot JT
FAU - Brown, S J
AU  - Brown SJ
FAU - Swaine, I L
AU  - Swaine IL
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PL  - Germany
TA  - Eur J Appl Physiol
JT  - European journal of applied physiology
JID - 100954790
SB  - IM
MH  - Adult
MH  - Blood Pressure
MH  - Blood Volume
MH  - Diastole
MH  - Female
MH  - Heart Rate
MH  - Humans
MH  - *Lower Body Negative Pressure/adverse effects
MH  - Male
MH  - Reproducibility of Results
MH  - Syncope/etiology
MH  - Systole
MH  - Time Factors
EDAT- 2001/06/22 10:00
MHDA- 2002/01/05 10:01
CRDT- 2001/06/22 10:00
PHST- 2001/06/22 10:00 [pubmed]
PHST- 2002/01/05 10:01 [medline]
PHST- 2001/06/22 10:00 [entrez]
AID - 10.1007/s004210100398 [doi]
PST - ppublish
SO  - Eur J Appl Physiol. 2001 May;84(5):462-8. doi: 10.1007/s004210100398.