Exercise is the free elixir of life. Our bodies have evolved over millennia into these beautiful machines that are designed for performance. Human bodies are supposed to perform physical feats of strength, endurance and agility. This is because since our prehistoric days, these abilities were vital to ensure our everyday survival. Through natural selection, we developed capacities which were indispensable.
We developed strength so we could fight off predators. We gained endurance to be able to follow our prey over large swathes of land. We developed agility essential to survival in the wild. (Trivia: amongst these three skills, the most impressive one would have to be our endurance. We may not be the strongest or the most agile animals out there, but in endurance running humans can easily beat animals like the cheetah and the horse.) Our physical abilities were the foundation on which we thrived in the wild and on which, this marvel of modern civilisation was built.
Science has been trying to determine the impact of a fit lifestyle on a significant aspect of our lives, our mental abilities. As we grow older, exercise has been proven to be neuroprotective, that is, beneficial in maintaining the structural integrity of our ageing brains. Physical activity has also shown improvement in our cognitive functioning as we age.
In a recent study, by University of Maryland, the effects of exercise on different higher mental faculties of middle aged and older persons was observed. The study also tried to determine the relation between blood pressure mediating the association between executive functions and fitness.
The experiment used Cardiorespiratory Fitness (CRF) as a measure of determination of fitness. CRF refers to the capacity of the circulatory and respiratory systems to supply oxygen to the skeletal muscle for generation of energy required to sustain physical activity. In simple words, CRF is an estimate of the endurance of the person. It can reduce the risk of heart disease, lung cancer, type 2 diabetes, stroke, and other diseases. It is considered a good measure for physical fitness.
In this study, cardiorespiratory fitness was determined by a six-minute bike test using a recumbent cycle ergometer.
Higher mental faculties for the subjects were estimated from the executive functions. Executive functions are a set of cognitive processes vital to control behaviour. They include attention control, cognitive inhibition, inhibitory control, etc. Multiple executive functions need to be engaged simultaneously for higher level fluid intelligence. As we age, this ability diminishes.
Specific tests of the Delis-Kaplan Executive Function system were utilised to assess the subjects.
Mean arterial pressure was used as the blood pressure parameter in this study. Mean arterial pressure (MAP) is defined as the average arterial pressure throughout one cardiac cycle, systole, and diastole. It is considered as a good measure of tissue perfusion. Tissue perfusion also has an effect on cognition as good quality perfusion maintains the energy intensive higher functions of the brain properly.
The data collected from the sample of subjects were analysed in statistical models and the results found significant effects of CRF on the executive functions of the brain. On comparison, there were significant associations of CRF and MAP, and MAP and executive function composites, within the mediation models.
The study found that how well we maintain our cardiovascular and respiratory health impacts how mentally fit we are as we age. The study also suggested the importance of both our cardiorespiratory fitness and maintenance of blood pressure in middle age and younger old age, shifting the focus from current cornerstone of addressing them usually in later old age. There seems to be a cumulative accumulation of the benefits of physical fitness over time.
A limitation of this study was its cross-sectional nature, observing the sample subjects at a particular point in their lives and recording their data to the model. It would have been a more comprehensive analysis if the subjects were followed up for longer durations to consider the changes with time.
This study does show us the merits of starting early. We should strive to control our blood pressure and maintain cardiorespiratory fitness before old age sets in to derive maximum prophylactic benefits of exercise on our higher cognitive functions. So, when are you starting to use those jogging sneakers?
Author: Joydev Bhattacharjee
Mean arterial pressure, fitness, and executive function in middle age and older adults - Marissa A. Gogniat, Junyeon Won, Daniel D. Callow, J. Carson Smith - Cerebral Circulation - Cognition and Behavior 2022 – DOI: 10.1016/j.cccb.2022.100135