Author(s): LEITAO, L., SILVA, M., PAREJA-BLANCO, F., Institution: SUPERIOR SCHOOL OF EDUCATION OF POLYTECHNIC INSTITUTE OF SETUBAL, Country: PORTUGAL, Abstract-ID: 556

INTRODUCTION:
The prefrontal cortex (PFC) plays a central role in motor execution by integrating cognitive and decision-making processes during physical effort (Leitão et al., 2025; Orcioli-Silva et al., 2024). Exercise tolerance is highly dependent on sufficient cerebral blood flow and oxygen availability, both of which increase substantially during physical activity compared with resting conditions (Leitão et al., 2025; Teo et al., 2023; Orcioli-Silva et al., 2024). Resistance training can be performed under different load settings, promoting distinct neural and physiological demands. Thus, the present study examined cerebral hemoglobin (Hb) dynamics during two maximal bench press protocols.
METHODS:
Twenty-two men (29.6±3.2 years; 81.4±4.1 kg; 1.81±0.05 m) performed 3 (3RM) and 10 (10RM) repetitions until failure in bench press, with 72 h of rest between them randomly. PFC response was analyzed by near-infrared spectroscopy to measure the concentration of oxygenated Hb (O2Hb), deoxygenated Hb (HHb), and tissue oxygenation index (TOI). In both the 3RM and 10RM protocols, the initial, the third, and the final repetitions were examined to characterize the PFC responses across these efforts.
RESULTS:
Repeated-measures ANOVA showed significant “Load” and “Repetitions” effects for O2Hb, HHb, and TOI (all p < 0.001). Significant “Load × Repetitions” interactions were observed for O₂Hb, HHb, and TOI (all p < 0.001). O₂Hb was higher in 3RM vs. 10RM at both initial (19.78 ± 5.2 vs. 12.45 ± 4.5 µmol/L) and final repetitions (28.19 ± 4.2 vs. 17.19 ± 6.2 µmol/L; both p < 0.05). HHb increased more in 3RM and TOI decreased with a higher reduction in 3RM (p < 0.05).
CONCLUSION:
In conclusion, fatigue accumulation during both maximal protocols was characterized by a progressive reduction in TOI alongside an increase in O2Hb, with heavier loads inducing a more pronounced and earlier response.

REFERENCES
Leitão L, Pareja-Blanco F, Marinho D, Neiva H. Effects of Different Back Squat Protocols on Prefrontal Cortex Oxygenation Responses. J Strength Cond Res. 2025 May 16;39(8):845-849. doi: 10.1519/JSC.0000000000005141

Teo WP, Tan CX, Goodwill AM, Mohammad S, Ang YX, Latella C. Brain activation associated with low- and high-intensity concentric versus eccentric isokinetic contractions of the biceps brachii: an fNIRS study. Scand J Med Sci Sports. 2023;34(1). doi:10.1111/sms.14499.

Orcioli-Silva D, Beretta VS, Santos PCR, et al. Cerebral and muscle tissue oxygenation during exercise in healthy adults: A systematic review. J Sport Health Sci 2024;13:459 71.