Temporal Interactions between Maintenance of Cerebral Cortex Thickness and Physical Activity from an Individual Person Micro-Longitudinal Perspective and Implications for Precision Medicine

Maintenance of brain structure is essential for neurocognitive health. Precision medicine has interests in understanding how maintenance of an individual person's brain, including cerebral cortical structure, interacts with lifestyle factors like physical activity. Cortical structure, including cortical thickness, has recognized relationships with physical activity, but concepts of these relationships come from group, not individual, focused findings. Whether or how group-focused concepts apply to an individual person is fundamental to precision medicine interests but remains unclear. This issue was studied in a healthy man using concurrent micro-longitudinal tracking of magnetic resonance imaging-defined cortical thickness and accelerometer-defined steps/day over six months. These data permitted detailed examination of temporal relationships between thickness maintenance and physical activity at an individual level. Regression analyses revealed graded significant and trend-level temporal interactions between preceding activity vs. subsequent thickness maintenance and between preceding thickness maintenance vs. subsequent activity. Interactions were bidirectional, delayed/prolonged over days/weeks, positive, bilateral, directionally asymmetric, and limited in strength. These novel individual-focused findings in some ways are predicted, but in other ways remain unaddressed or undetected, by group-focused work. We suggest that individual-focused concepts of temporal interactions between maintenance of cortical structure and activity can provide needed new insight for personalized tailoring of physical activity, cortical, and neurocognitive health.

Effect of handling breaks on estimation of heart rate responses to bouts of physical activity among young women: An accelerometer research issue

BACKGROUND

One of the research interests with regard to accelerometry is the evaluation of physical activity bout under free-living conditions.

RESEARCH QUESTION

This study aimed to examine the effect of treatment interruption on the estimation of heart rate (HR) response to moderate-to-vigorous intensity physical activity (MVPA) bout.

METHODS

Twenty-five young women performed at least 30 min of MVPA during 24 h while wearing a uniaxial accelerometer on their waist and a portable HR monitor on their chest simultaneously. Based on the time series data, MVPA bout was defined as physical activity that was maintained at no less than 3 metabolic equivalents (METs) for >10 min without or with interruption, i.e., a 1-, 2-, or 3-min interruption.

RESULTS

The frequency and duration of MVPA bout significantly increased with interruption (p < 0.01). The HR and estimated MET value for an MVPA bout with interruption were significantly lower than those without interruption (p < 0.01), and the difference gradually increased depending on the duration of the interruptions (p < 0.01).

SIGNIFICANCE

These findings indicate that treatment interruptions could influence the estimation of cardiorespiratory response to MVPA bout under free-living conditions, and interruptions could result in an overestimation of the actual intensity of an MVPA bout.