•  
  •  
 

Abstract

Resistance exercise (RE) enhances cognitive function potentially through increases in cerebral blood flow and oxygenation (O2Hb). These exercise-induced changes in cerebral blood flow and concomitant neural activity reflect the neurovascular coupling. Blood flow restriction (BFR) combined with low-load (LL) RE is an effective tool for increasing muscle excitation, size, and strength. However, the effects of BFR RE on cerebral oxygenation responses remain unknown. PURPOSE: Therefore, our purpose was to compare the effects of LL, LL + BFR, or (high-load) HL volume-equated squats on changes in prefrontal cortex (PFC) oxygenation and muscle excitation in adults. METHODS: Thirty healthy, young adults (15 female, age: 24±5yrs, height: 168.1±9.0cm, weight: 71.9±12.6kg) participated in this investigation. Participants completed a one-repetition maximum (1RM) squat assessment and 3 randomized, volume-equated squat conditions: LL, LL + BFR, and HL. Functional near-infrared spectroscopy measured PFC O2Hb during all sets, and values were expressed as a change score from a pre-exercise resting baseline. Muscle excitation was recorded via surface electromyography amplitude (EMG AMP) on the dominant vastus lateralis and values expressed as the change across the set (i.e., last three – first three repetitions). LL protocols consisted of four sets (1×30, 3×15) at 30% 1RM, and HL consisted of four sets of 8 repetitions at 70% 1RM. BFR was applied at 40% of the pressure needed to occlude each femoral artery. A 2 (Sex [male, female]) x 3 (Condition [LL, LL+ BFR, HL]) x 4 (Set [1, 2, 3, 4]) repeated measures ANOVA evaluated mean differences in PFC O2Hb and muscle excitation across conditions and sets. A pRESULTS: For PFC O2Hb, there was no significant three-way (p=0.314) or two-way interactions (p=0.694); however, there was a significant main effect for Set (p < 0.001, ηp²= 0.345). Post hoc pairwise comparisons indicated that the change was greater in Sets 2 (p < 0.001, d = 0.166), 3 (p < 0.001, d = 0.389), and 4 (p < 0.001, d = 0.438) compared with Set 1. Sets 3 (p < 0.001, d = 0.223) and 4 (p < 0.001, d = 0.272) were greater than Set 2, with no difference between Sets 3 and 4 (p = 0.958, d =0.49). No significant three-way (p= 0.131) or two-way (p= 0.173) interactions or main effects were found for EMG AMP (p >0.05). CONCLUSION: PFC O2Hb increased similarly across sets irrespective of exercise condition or sex, whereas changes in muscle excitation did not differ. Initial increases in PFC O2Hb likely reflect increased cerebral arousal and metabolic demand, while the absence of parallel EMG AMP changes suggests cerebral oxygenation may not directly mirror peripheral neural drive. Therefore, health professionals may employ RE to acutely increase PFC O2Hb, through which RE may benefit cognition.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.