Work

Effect of combat gear and body armor on ventilatory thresholds and muscle oxygenation during graded treadmill exercise in female and male soldiers

Year: 2026

Type: article

Abstract: Introduction This study aimed to determine how combat gear and body armor (CB) affect the relationship between treadmill setting and internal physiological responses at ventilatory transitions, and to characterize right vastus lateralis muscle oxygen saturation (SmO 2 ) and exploratory early reoxygenation in female and male soldiers. Methods Nine female and nine male soldiers completed randomized no-load (NL) and CB graded treadmill tests to volitional exhaustion. Heart rate and pulmonary gas exchange were measured, and right vastus lateralis SmO 2 was assessed using near-infrared spectroscopy. VT1 was identified using the V-slope method and VT2 using ventilatory-equivalent criteria. SmO 2 outcomes were referenced to a 30-s standing value. Results VT1 was identified at a lower treadmill stage in CB than in NL in men (5.2 ± 0.8 vs. 6.4 ± 1.7; p = 0.02) and women (5.1 ± 0.6 vs. 7.1 ± 1.5; p <0.01). Absolute V̇O 2 at VT1 changed little, whereas HR was higher in CB in men (p <0.01) and women (p = 0.04). VT2 was also identified at a lower stage in CB in both groups (p <0.01). Baseline-referenced right vastus lateralis desaturation amplitude during CB was greater in men than women (39.0% ± 23.9% vs. 17.1 ± 14.5%; p <0.01), although adipose-tissue thickness at the sensor site was not measured. No statistically significant effects were detected for the early post-exercise indices. Discussion CB altered the treadmill setting at which ventilatory transitions were observed and increased cardiovascular demand at VT1 without essentially changing absolute V̇O 2 at VT1. This indicates a changed relationship between treadmill task, transported mass, and internal physiological response rather than demonstrated displacement of the underlying metabolic threshold. The site-specific SmO 2 and early reoxygenation findings were exploratory, and between-sex interpretation was limited by the small sample and unmeasured adipose-tissue thickness.

Source: Frontiers in Physiology

DOI: 10.3389/fphys.2026.1943048

Authors: Jonas Larsson, Magnus Dencker, Ann Bremander, M. Charlotte Olsson