Adiposity is associated with improved neuromuscular reaction time

Abstract

Many studies have focused on the detrimental effects of malnourishment to the performance of the brain and peripheral nerves. Undernourished children and adults have been studied extensively to establish these consequences. Little attention has been given to the body habitus that affects optimum neurological performance and the implications for individuals on the spectral extremes of the healthy weight range. This paper examines the association between markers of adiposity and neurological performance, inclusive of all body types. The data were obtained from Cape Coloured youths (5–20 years) in South Africa from the rural district of Klein Karoo and the urban population of Cape Town. In all, the sums of skin-folds were measured for almost 4000 students. The neuromuscular reaction time was also calculated using a ruler drop test. This measure may serve as a gross marker of peripheral and central neurological performance as both are needed to execute the reflex command. There was a direct correlation between adiposity and neuromuscular reaction time. Whilst controlling for age, increasing fatness was associated with a decrease in neuromuscular reaction time amongst both sexes. This relationship remained statistically significant, even when removing the thinnest 40% of participants, eliminating the scope of influence exerted by malnourishment on the correlation. The trend appears to be more prominent amongst boys. These findings indicate that body lipid reserves are integral to the development of the nervous system even amongst children within the healthy weight ranges. Our hypothesis is that the myelination of the nerves, both centrally through oligodendrocytes and peripherally by Schwann cells, is integral to this process as they are predominantly lipid. Amongst thin but not clinically undernourished individuals, the somatic lipid reserves are modest. These fats may be minimally sequestered away for the development of myelin nerve sheath at the expense of saltatory conduction. This may account for the slowed neuromuscular reaction time demonstrated.