Author(s): DE NIGRIS, E., GALVAN-ALVAREZ, V.1,2,3, GARCIA-GONZALEZ, E.2, GARCIA-PEREZ, G.1,2, MARTINEZ-CANTON, M.1,2, PONCE-GONZALEZ, J.G.1,2, LARSEN, S.5,6, LOSA-REYNA, J.1,2, PEREZ-SUAREZ, I.1,2, SANTANA, A.2,4, GONZALEZ-HENRIQUEZ, J.J.1,2,7, GALLEGO-SELLES, A.1,2, HELGE, W.J.5, MARTIN-RINCON, M.1,2, CALBET, J.A.L.1,2,8, Institution: UNIVERSITY OF LAS PALMAS OF GRAN CANARIA, Country: ITALY, Abstract-ID: 2783

INTRODUCTION:
The renin–angiotensin system (RAS) modulates skeletal muscle vascular and metabolic function, with the balance between the “classical” ACE1/Ang II/AT1R axis and the counter-regulatory ACE2/Ang-(1–7)/MasR and AT2R pathways shaping cardiometabolic risk. Although exercise training improves cardiometabolic health, the extent to which high-intensity interval training (HIIT) remodels the human skeletal muscle RAS, and whether this is sex-dependent, remains unknown.
METHODS:
Volunteers with overweight/obesity (n=97; 52 males/45 females; 18–52 yr) completed 6-week HIIT (3 d/wk, two protocols: 7x1’ at ~100% Wmax with 1’ recovery, or 5x1’ at higher work rates with 90-s recovery) or remained sedentary (n=9). Vastus lateralis biopsies were obtained pre-training, ≥48 h post-training, and after 3 weeks of detraining. Protein expression of ACE2, ACE1, AT1R, AT2R, MasR, and the ACE2 sheddases ADAM17 and TMPRSS2 was quantified by Western blotting. VO₂max and Wmax by ergospirometry, and oral glucose tolerance tests were performed pre-, post-, and after detraining. Stats: Linear mixed-effects models that included time, training type, and sex.
RESULTS:
At baseline, females displayed a more counter-regulatory skeletal muscle RAS profile than males, with higher AT2R (+17%, p=0.042), lower ACE1 (−13%, p=0.035), and a trend toward higher ACE2 (~1.7-fold, p=0.061). Consistent with these molecular differences, systolic blood pressure was modestly lower in females. HIIT increased aerobic fitness (VO₂ max: HIIT1 +4.8%, p=0.050; HIIT2 +7.7%, p<0.001; time effect p<0.001) and Wmax, with minimal changes in body composition and no significant improvements in fasting glucose or insulin sensitivity indices at the group level. Skeletal muscle ACE2 protein increased ~1.8-fold after training (p=0.003; training x time p=0.016), and the ACE2/ACE1 ratio increased ~1.7-fold (p<0.014; training x time p=0.009), remaining elevated after 3-week detraining. TMPRSS2 increased ~60% (p=0.003) with a larger response in the lower-intensity/higher-volume protocol. In females only, AT1R decreased (−14%, p=0.034; more pronounced after the higher-intensity protocol) and ADAM17 decreased (−13%, p=0.004), changes that persisted after detraining. AT2R and MasR were unchanged. Training-induced changes in ADAM17 and TMPRSS2 jointly explained ~50% of the variance in ACE2 upregulation, suggesting coordinated regulation of ACE2 abundance and processing.
CONCLUSION:
In adults with overweight/obesity, HIIT upregulates skeletal muscle ACE2 and increases the ACE2/ACE1 ratio, shifting the local RAS towards a healthier profile. Females show additional attenuation of AT1R and ADAM17. These findings identify skeletal muscle ACE2 as an exercise-responsive target and potential fitness-related biomarker, and suggest sex-specific modulation of RAS regulatory mechanisms with high-intensity interval training.

Grants: HEALTH-F2-2012-277936, PID2021-125354OB-C21, SD-24/03 (ID 877) CUCIC.