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

Kwo-Tsao Chiang, Min-Yu Tu, You-Jin Lin, Yi-Hsiang Hsin, Yu-Lung Chiu, Fang-Ling Li, Hsin-Hui Chen, Chung-Yu Lai, Kwo-Tsao Chiang, Min-Yu Tu, You-Jin Lin, Yi-Hsiang Hsin, Yu-Lung Chiu, Fang-Ling Li, Hsin-Hui Chen, Chung-Yu Lai

Abstract

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.

Keywords: G force; G tolerance; anti-G straining maneuver; cardiac force index; relaxed G tolerance; straining G tolerance.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Study protocol.
Figure 2
Figure 2
BioHarness 3.0 module attached to chest and shoulder straps.
Figure 3
Figure 3
Human centrifuge in APRL.
Figure 4
Figure 4
G tolerance test inside the gondola view.
Figure 5
Figure 5
Light bars as the visual reference.
Figure 6
Figure 6
Linear association between the cardiac function and G tolerance. RCFI: resting cardiac force index; WCFI: walking cardiac force index; CFR: cardiac force ratio; RGT: relaxed G tolerance; SGT: straining G tolerance; r: Pearson correlation coefficient.

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Source: PubMed

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