Author(s): LEITAO, L., PAREJA-BLANCO, F., MARINHO, D., NEIVA, H. , Institution: SUPERIOR SCHOOL OF EDUCATION OF POLYTECHNIC INSTITUTE OF SETUBAL, Country: PORTUGAL, Abstract-ID: 643

INTRODUCTION:
Coordination and strength are essential to perform technical gestures during training and competition. These motor tasks are connected to the prefrontal cortex (PFC) response since the decision to maintain exercise is affected by sufficient blood flow and oxygenation supply for brain function. Cerebral hemoglobin consumption during high loads in strength exercises may change until failure in response to fatigue. Our study goal was to analyze cerebral hemoglobin consumption during two maximal protocols in the back squat exercise.
METHODS:
Twelve men (29.2 ± 4.3 years; 81.5 ± 2.2kg; 1.72 ± 0.19m) performed 6 (6RM) and 10 (10RM) repetitions until failure in back squat, with 72h of rest between. PFC response was analyzed by NIRS to measure the concentration of oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), total hemoglobin (tHb), and tissue oxygenation index (TOI). The first and last repetitions were analyzed in both protocols (6RM and 10RM) to understand the PFC responses up to failure (last repetition of both protocols) and non-failure (first repetition of both protocols) efforts.
RESULTS:
O2Hb was higher in 6RM than in 10RM in the first (8.12 ± 2.5 vs 5.41 ± 3.3 µmol/L) and last repetition (16.5 ± 5.5 vs 7.7 ± 4.5 µmol/L). No differences were observed in HHb and TOI between protocols. tHB incresed in both protocols from the first until the last repetition (6RM: 6.53 ± 2.2 µmol/L - 14.93 ± 5.27 µmol/L; 10RM: 3.41 ± 2.16 µmol/L - 6.01 ± 2.77 µmol/L ). O2Hb was higher in the last repetition than in the first one for both protocols (p<0.05).
CONCLUSION:
Increasing fatigue during 6RM and 10RM promoted a progressive increase in HbO2 and tHB response until failure being higher with heavier loads.