Biomarker and cognitive effects of single bouts of moderate-intensity neuro-exergaming, high-intensity interval training (HIIT), and fasted exercise for mild cognitive impairment: A case study of serial interventions

Research has demonstrated benefits of exercise on cognition, but it remains unclear whether adjusting other variables can maximize the benefit. This case study examined the effects of fasting and moderate to high-intensity physical exercise on cognitive function and biomarkers in an older adult with mild cognitive impairment (MCI). We hypothesized that (1) cognition would improve throughout the intervention, (2) salivary cortisol would increase after fasted moderate exercise and high-intensity interval training (HIIT) and decrease after non-fasted moderate exercise, and (3) salivary alpha-amylase would increase after all exercise conditions. One adult participant completed all four study conditions: (1) fasting only, (2) non-fasting with moderate iPACES (neuro-exergaming) exercise, (3) fasting with moderate iPACES exercise, and (4) non-fasting with HIIT using iPACES. All study procedures were administered remotely due to the COVID-19 pandemic. The participant self-collected saliva samples using materials shipped to her residence from our lab. Cognition was assessed via the Montreal Cognitive Assessment (MoCA) and executive function via the "paper" Stroop test administered via videoconference pre/post intervention. Additionally, a digital Stroop test was administered pre/post each of the four serially assigned conditions. A time series display illustrated a slight improvement in the participant on the paper Stroop task from pre- to post-intervention with only slight improvement on the MoCA, possibly due to practice effects. However, we saw a marked improvement on the digital Stroop test following the fasted moderate exercise bout (the third condition in the series) despite its repeated administration. Biomarker analyses showed some increase in alpha-amylase for the non-fasted aerobic exercise condition and the HIIT condition. Pre/post for the fasting and fasted aerobic exercise conditions were similar. For cortisol, there was some decrease for the fasting condition and a marked decrease for the HIIT condition. Pre/post for both non-fasted and fasted aerobic exercise conditions were similar. The results partially supported our hypotheses and replicated previous findings from the literature, but further research with a sampling of additional participants is needed for statistical analyses to confirm our findings. This study tested the feasibility of our newly home-based neuro-exergaming intervention and a novel method of collecting and shipping biomarker samples for analysis. While we demonstrated the necessity of certain tools for our protocol, it had several limitations. These include difficulties with participant recruitment, the expensive and time-consuming shipping process, and faulty Bluetooth connections between fitness watch, Lenovo tablet, and cadence meter. Results also warrant further research to clarify possible moderating roles of other neuroprotective biomarkers (like BDNF or ketone bodies) as well as heart rate and diet regimen.