Author(s): WU, J., HSU, T.M., LAI, Y.L., LIU, H.J., LIAO C.H., LIN J.Z., Institution: NATIONAL TAIWAN UNIVERSITY OF SPORT, Country: TAIWAN, Abstract-ID: 1195

INTRODUCTION:
The human core broadly encompasses the abdominal, lumbar, gluteal, and pelvic regions. The steady-state pressure generated by the interaction between the abdominal wall and visceral contents is defined as intra-abdominal pressure (IAP)(1). IAP is influenced by core muscle activation, and previous studies have shown that contraction of adjacent core musculature during exercise significantly elevates IAP. However, real-time measurement of IAP during exercise remains limited, leaving its dynamic variability across exercise modalities unclear. Therefore, this study employed a novel wireless intra-abdominal pressure monitoring capsule to characterize IAP responses under different exercise conditions and to further examine its dynamic regulation as exercise intensity progressed toward fatigue.
METHODS:
Eighteen male athletes were recruited for this study. Participants completed Bruce incremental treadmill test until volitional exhaustion. Prior to testing, participants ingested a PressureDot wireless pressure-sensing capsule. Based on ventilatory thresholds, exercise intensity was categorized into three metabolic zones: Zone 1 (< VT1), Zone 2 (VT1-VT2), and Zone 3 (> VT2). Differences in IAP characteristics across intensity zones were analyzed using one-way repeated-measures ANOVA, and Pearson’s product-moment correlation was used to examine the relationship between IAP and V̇O₂.
RESULTS:
Statistical analysis showed that respiratory metabolic stage had a significant effect on both mean IAP and IAP variability (p < 0.001). Post hoc comparisons revealed that mean IAP and variability were significantly higher in Zone 2 and Zone 3 than in Zone 1. In addition, the absolute IAP fluctuation sum (AS value) showed a strong positive linear relationship with oxygen consumption (V̇O₂) (mean R² = 0.873).
CONCLUSION:
The present study demonstrated that both the mean level and variability of IAP increased significantly across ventilatory thresholds during incremental treadmill exercise. These findings indicate an intensity-dependent modulation of IAP, with greater fluctuations observed beyond VT1. The strong positive association between accumulated IAP fluctuations and V̇O₂ suggests that IAP dynamics reflect increasing metabolic demand during exercise. This may represent the integrated function of respiratory and trunk musculature under elevated ventilatory requirements. The proposed AS value provides a novel approach to quantify dynamic IAP behavior while minimizing individual baseline differences. Collectively, these findings suggest that IAP monitoring may serve as a potential non-invasive indicator of core loading during incremental exercise.