The Inherent Human Aging Process and the Facilitating Role of Exercise

Abstract

Arguably the best available depictions of the global physiological changes produced by age are the profiles of world record performance times in swimming, athletics, and cycling, depicting the trajectory of decline in maximal integrated physiological performance capability. The curves suggest that the aging process produces a synchronized, controlled decrease in physiological performance over the human lifespan. The shape of the performance profile by age is essentially independent of discipline, distance, or phenotype. Importantly, the specific times of performance are not the driving force in the production of the shape of the declining performance profile. We suggest that in these highly trained individuals the shape of the curve is generated by the aging process operating on a physiology optimized for any given age. We hypothesize that with adequate training this same profile and trajectory, but with lower performance times, would be generated by all individuals who engage in sufficient physical activity/exercise. Unlike performance, data obtained from examining individual physiological systems or tissues do not give information on the unceasing and changing global integrating functions of the aging process. However, these data do give valuable information about the integrity of physiological systems at a particular age and allow a direct comparison to be made between the effects of inactivity and physical activity/exercise. Being physically active has been shown to have global protective effects on physiological systems and thus facilitates the aging process by maintaining physiological integrity. There is emerging evidence which suggests that physiological regulation of aging may be multi-compartmentalized. We do not advocate exercise as a panacea, but all the evidence indicates that being physically active and exercising is far superior to any other alternative for achieving optimal aging.

Keywords: aging; exercise; healthspan; performance; physiology.

FIGURE 1

Theoretical longitudinal maximum performance curves (e.g., swimming, running, cycling) for athletes as they age [based on cross-sectional data from World Record performances, Baker and Tang (2010), gold]. Inherently aging individuals exercising at Set Point (green) are predicted to have the same trajectory of decline if they were to undertake a similar athletic event at regular intervals as they age (depicting the change in integrative whole-body physiology due to aging), but with inferior performances. Maintaining the same profile, but improving athletic performance is possible by increasing exercise towards the gold zone. Those below set point show an unpredictable trajectory (red). The black arrows indicate the change to different performance curves with increased levels of physical exercise, the green crosses indicate that if exercising at set point there can be no acceleration or deceleration (i.e., deviation from the predicted curve which represents inherent aging) – assuming no disease. The red dotted curve and question mark indicate both an uncertain trajectory, or indeed the very possibility, of being able to undertake a maximal performance.

FIGURE 2

Schematic showing the effects of exercising below (red), at (green), or above (gold) the Set Point. Any protective effects of moving from gold/green to red are unclear (but overall effects are negative). The progression from red through to green will be an overall positive effect, whilst the progression from red through to gold and being able to fulfill athletic potential in later life is unclear. PAE refers to Physical Activity/Exercise.

FIGURE 3

Schematic depicting the compartmentalisation of factors that impact on aging. The assumption here is that no pathologies are present. PAE refers to Physical Activity/Exercise.