No changes in corticospinal excitability, biochemical markers, and working memory after six weeks of high‐intensity interval training in sedentary males

Abstract

A single bout of aerobic exercise modulates corticospinal excitability, intracortical circuits, and serum biochemical markers such as brain‐derived neurotrophic factor ( BDNF ) and insulin‐like growth factor 1 ( IGF ‐1). These effects have important implications for the use of exercise in neurorehabilitation. Here, we aimed to determine whether increases in cardiorespiratory fitness ( CRF ) induced by 18 sessions of high‐intensity interval training ( HIIT ) over 6 weeks were accompanied by changes in corticospinal excitability, intracortical excitatory and inhibitory circuits, serum biochemical markers and working memory ( WM ) capacity in sedentary, healthy, young males. We assessed motor evoked potential ( MEP ) recruitment curves for the first dorsal interosseous ( FDI ) both at rest and during tonic contraction, intracortical facilitation ( ICF ), and short‐interval intracortical inhibition ( SICI ) using transcranial magnetic stimulation ( TMS ). We also examined serum levels of BDNF , IGF ‐1, total and precursor (pro) cathepsin B ( CTSB ), as well as WM capacity. Compared to pretraining, CRF was increased and ICF reduced after the HIIT intervention, but there were no changes in corticospinal excitability, SICI , BDNF , IGF ‐1, total and pro‐ CTSB , and WM capacity. Further, greater CRF gains were associated with larger decreases in total and pro‐ CTSB and, only in Val/Val carriers, with larger increases in SICI . Our findings confirm that HIIT is efficacious in promoting CRF and show that corticospinal excitability, biochemical markers, and WM are unchanged after 18 HIIT bouts in sedentary males. Understanding how aerobic exercise modulates M1 excitability is important in order to be able to use exercise protocols as an intervention, especially in rehabilitation following brain injuries.

Effect of four different forms of high intensity training on BDNF response to Wingate and Graded Exercise Test

“…Reduction or no BDNF level changes observed after WAnT or high intensity training were noted by several authors 62 – 64 , 78 – 80 . Hebisz et al 64 found no changes in BDNF at baseline, as well as after two and six months’ of SIT training.…”

Systematic review of the acute and chronic effects of high-intensity interval training on executive function across the lifespan

“…However, the existing data does not support a positive influence of chronic HIIT to inhibition in older adults (Coetsee & Terblanche, 2017;Kovacevic et al, 2020), which may suggest further contemplation for implementing HIIT protocols in older adults. The current data on other subcomponents of executive function are scarce, with positive effects on working memory found among middle-aged adults (Connolly et al, 2017) but not young adults (Nicolini et al, 2019), and null effects also noted for cognitive flexibility in young adults . Nevertheless, more research is needed considering that these three studies differ from each other extensively in participants' age, study design, HIIT protocol, and/or training duration (i.e., 6 weeks vs. 8 weeks vs. 12 weeks).…”

Effect of High Intensity Interval Training Compared to Continuous Training on Cognitive Performance in Young Healthy Adults: A Pilot Study

“…Although these results are encouraging, there is no clear evidence that HIIT has a superior effect on cognitive function compared to MICE [16]. Recently, original studies have provided more responses with null [31,32] or positive results [33][34][35][36][37] in animal and human studies. Among the studies that achieved positive results, they only compared HIIT to active controls, and as such, the effects of exercise intensity per se were not examined.…”