Stunted PFC activity during neuromuscular control under stress with obesity.
OBJECTIVE
Obesity is an established risk factor for impaired cognition, which is primarily regulated by the prefrontal cortex (PFC). However, very little is known about the neural pathways that underlie obesity-related declines in neuromuscular control, particularly under stress. The purpose of this study was to determine the role of the PFC on neuromuscular control during handgrip exertions under stress with obesity.


METHODS
Twenty non-obese and obese young adults performed submaximal handgrip exertions in the absence and presence of a concurrent stressful task. Primary dependent measures included oxygenated hemoglobin (HbO2: a measure of PFC activity) and force fluctuations (an indicator of neuromuscular control).


RESULTS
Higher HbO2 levels in the PFC were observed in the non-obese compared to the obese group (P = 0.009). In addition, higher HbO2 levels were observed in the stress compared to the control condition in the non-obese group; however, this trend was reversed in the obese group (P = 0.043). In general, force fluctuations increased by 26% in the stress when compared to the control condition (P = 0.001) and obesity was associated with 39% greater force fluctuation (P = 0.024). Finally, while not significant, obesity-related decrements in force fluctuations were magnified under stress (P = 0.063).


CONCLUSIONS
The current study provides the first evidence that neuromuscular decrements with obesity were associated with impaired PFC activity and this relationship was augmented in stress conditions. These findings are important because they provide new information on obesity-specific changes in brain function associated with neuromuscular control since the knowledge previously focused largely on obesity-specific changes in peripheral muscle capacity.
Department of Environmental and Occupational Health, Texas A&M University, College Station, TX, 77843, USA. rmehta@tamu.edu.
Ranjana K
http://orcid.org/0000-0002-8254-8365
RK
Mehta
D016022:Case-Control Studies; D005260:Female; D018737:Hand Strength; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D010108:Oxyhemoglobins / Q000378:metabolism; D017397:Prefrontal Cortex / Q000502:physiology*; D013315:Stress, Psychological / Q000150:complications / Q000503:physiopathology*; D055815:Young Adult
D010108:Oxyhemoglobins
BMI; Cortical activity; Mental arithmetic; Motor control; fNIRS