Subjective and Objective Measures of Relaxed +G&lt;SUB&gt;z&lt;/SUB&gt; Tolerance Following Repeated +G&lt;SUB&gt;z&lt;/SUB&gt; Exposure

Scott, Jonathan; Jungius, James; Connolly, Desmond; Stevenson, Alec

doi:10.3357/asem.3550.2013

Cited by 14 publications

(8 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this study, the average values of RGT and SGT were 5.1 G and 7.8 G, respectively, among the participants. Previous results have noted that age, flight experience/hour [24,25], and repeated exposure to a high-G environment [2,9,26] were positive factors correlated with G tolerance. The mild discrepancy in SGT might well result from the different age subgroups of male military aircrew members.…”

Section: Discussionmentioning

confidence: 97%

A Cardiac Force Index Applied to the G Tolerance Test and Surveillance among Male Military Aircrew

Chiang

Lin

et al. 2021

IJERPH

View full text Add to dashboard Cite

Military aircrew are occupationally exposed to a high-G environment. A tolerance test and surveillance is necessary for military aircrew before flight training. A cardiac force index (CFI) has been developed to assess long-distance running by health technology. We added the parameter CFI to the G tolerance test and elucidated the relationship between the CFI and G tolerance. A noninvasive device, BioHarness 3.0, was used to measure heart rate (HR) and activity while resting and walking on the ground. The formula for calculating cardiac function was CFI = weight × activity/HR. Cardiac force ratio (CFR) was calculated by walking CFI (WCFI)/resting CFI (RCFI). G tolerance included relaxed G tolerance (RGT) and straining G tolerance (SGT) tested in the centrifuge. Among 92 male participants, the average of RCFI, WCFI, and CFR were 0.02 ± 0.04, 0.15 ± 0.04, and 10.77 ± 4.11, respectively. Each 100-unit increase in the WCFI increased the RGT by 0.14 G and the SGT by 0.17 G. There was an increased chance of RGT values higher than 5 G and SGT values higher than 8 G according to the WCFI increase. Results suggested that WCFI is positively correlated with G tolerance and has the potential for G tolerance surveillance and programs of G tolerance improvement among male military aircrew.

show abstract

Section: Discussionmentioning

confidence: 97%

A Cardiac Force Index Applied to the G Tolerance Test and Surveillance among Male Military Aircrew

Chiang

Lin

et al. 2021

IJERPH

View full text Add to dashboard Cite

show abstract

“…Repeated exposure to LAHC can improve orthostatic tolerance (Scott et al . 2013), but is impractical and thus unlikely to be employed during spaceflight (Clément & Pavy‐Le Traon, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…almost constant gravitational force is experienced at the head and feet, Scott et al 2007). Repeated exposure to LAHC can improve orthostatic tolerance (Scott et al 2013), but is impractical and thus unlikely to be employed during spaceflight (Clément & Pavy-Le Traon, 2004).…”

Section: Introductionmentioning

confidence: 99%

Effect of novel short‐arm human centrifugation‐induced gravitational gradients upon cardiovascular responses, cerebral perfusion and g‐tolerance

Laing

Green

Mulder

et al. 2020

The Journal of Physiology

View full text Add to dashboard Cite

The aim of this study was to determine the effect of rotational axis position (RAP and thus g-gradient) during short-arm human centrifugation (SAHC) upon cardiovascular responses, cerebral perfusion and g-tolerance. r In 10 male and 10 female participants, 10 min passive SAHC runs were performed with the RAP above the head (P1), at the apex of the head (P2), or at heart level (P3), with foot-level Gz at 1.0 g, 1.7 g and 2.4 g. r We hypothesized that movement of the RAP from above the head (the conventional position) towards the heart might reduce central hypovolaemia, limit cardiovascular responses, aid cerebral perfusion, and thus promote g-tolerance. r Moving the RAP footward towards the heart decreased the cerebral tissue saturation index, calf circumference and heart rate responses to SAHC, thereby promoting g-tolerance. r Our results also suggest that RAP, and thus g-gradient, warrants further investigation as it may support use as a holistic spaceflight countermeasure.

show abstract

“…Heart rate (HR) was determined continuously from a three-lead ECG. Beat-to-beat blood pressure (Finapres 2300, Ohmeda, USA) was recorded using the volume-clamp method 25 , which is well-established for non-invasive trend monitoring in centrifuge studies 7,29 and has been shown to correlate well with intra-arterial line measurements 21 . .…”

Section: Anti-g Systems: Three Anti-g Systems Were Evaluated System 1 [S1] and Systemmentioning

confidence: 99%

“…All AGT elevate arterial blood pressure by increasing total peripheral resistance (TPR) and promoting venous return, which assists in the maintenance of stroke volume (SV) and thereby cardiac output (CO) 13 . Despite these effects, the assessment of G protection effectiveness has largely been confined to subjective estimates of the G-level reached at pre-determined visual end-points 16,24,29 .…”

Section: Introductionmentioning

confidence: 99%

Hemodynamic Responses and G Protection Afforded by Three Different Anti-G Systems

Pollock¹,

Firth²,

Storey³

et al. 2019

aerosp med hum perform

Self Cite

View full text Add to dashboard Cite

BACKGROUND: UK Royal Air Force fast jet aircrew use three different anti-G systems, however, little objective comparison of the G protection they provide exists. The G-protection afforded by each system and associated hemodynamic responses were investigated.METHODS: Ten subjects performed centrifuge acceleration exposures using Mk-10 (S1) and Mk-4 (S2) five-bladder anti-G trousers (AGT) and full coverage AGT plus pressure breathing for G-protection (PBG; S3). Measurements of relaxed G tolerance (RGT), eye-level blood pressure (BPeye), lower body blood volume (LBV), stroke volume (SV) and total peripheral resistance (TPR) were made during gradual onset runs (GOR) and rapid onset runs (ROR). The subjective effort required to maintain clear vision at +7 and +8 Gz provided an indication of the protection provided by the system.RESULTS: All systems moderated decreases in SV and BPeye and increases in LBV under increased +Gz. S3 provided the greatest mean RGT during GOR (+6.2 Gz) and ROR (+6 Gz), reduced the effort required to maintain clear vision at up to +8 Gz, prevented venous pooling and afforded the greatest rise in TPR. The majority of indices revealed no difference between S1 and S2 although RGT during the ROR was greater with S2 (+0.25 Gz).DISCUSSION: S3 effectively prevented pooling of blood in the lower limbs under +Gz, despite the use of PBG, and offers an advantage over five-bladder AGT. Given the similarities of S1 and S2, it was unsurprising that the majority of indices measured were similar. The objective measurement of hemodynamic parameters provides useful information for comparing the G-protection provided by anti-G systems.Pollock RD, Firth RV, Storey JA, Phillips KE, Connolly DM, Green NDC, Stevenson AT. Hemodynamic responses and G protection afforded by three different anti-G systems. Aerosp Med Hum Perform. 2019; 90(11):925–933.

show abstract

Subjective and Objective Measures of Relaxed +G<SUB>z</SUB> Tolerance Following Repeated +G<SUB>z</SUB> Exposure

Abstract: Frequent +Gz acceleration, either as 2 (8 SACMs) or 4 sessions (16 SACMs) per week for 3 wk, enhances cardiovascular tolerance to orthostatic stress but does not improve RGT measured during a GOR.

Cited by 14 publications

References 11 publications

A Cardiac Force Index Applied to the G Tolerance Test and Surveillance among Male Military Aircrew

A Cardiac Force Index Applied to the G Tolerance Test and Surveillance among Male Military Aircrew

Effect of novel short‐arm human centrifugation‐induced gravitational gradients upon cardiovascular responses, cerebral perfusion and g‐tolerance

Hemodynamic Responses and G Protection Afforded by Three Different Anti-G Systems

Contact Info

Product

Resources

About