In a perfect world, we want to be active and independent as we age and as functional as possible.
A paradigm shift is underway to classify people, not by a chronologic age, but by health status or functional ability to perform daily tasks. Let’s look at the hormonal system and how slightly manipulating exercise and activity we can support age-related changes in the hormonal system.
The human glandular system is made up of the pituitary, thyroid, parathyroid and adrenal glands, the pancreas and hypothalamus and either testis or ovaries. Dehydroepiandrosterone, or DHEA, is the mother hormone to the androgens and estrogens. DHEA levels peak at age 20-30 and decrease over time to about 20% of peak levels at 70-80.
Cortisol and DHEA are stress hormones, the difference being cortisol suppresses the immune system and causes neuron degeneration while DHEA enhances the immune system and protects the neuron from damage. Cortisol excess has been linked negatively to its influence on cognition, mood, sleep, attention, memory, loss of muscle mass and strength, increased risk of osteoporosis and socioemotional functioning.
The pituitary gland secretes the growth hormone and stimulates a liver hormone that is an extension of the growth hormone. Working together, they promote muscle growth and repair. These hormones also decline with age, growth hormone production declines 14% per decade after age 30 and in men 50% every 7 years. This reduction is associated with loss of muscle mass and exercise capacity leading to a decrease in the ability to perform previously daily activities.
Testosterone, the main hormone responsible for skeletal muscle growth and regeneration, also declines with age.
Women possess the only endocrine system to undergo an abrupt and universal age-related change in function, known as menopause. Estrogen plays a major role in the functioning of the physiological, neurological and metabolic systems. With the loss of estrogen, women are without defense against normal stress responses, muscle and strength loss, its neuro-protective effect on brain aging and the response to inflammation.
Regular physical activity in aging adults has a positive effect on life expectancy, according to the World Health Organization. In 2018, WHO reported a global increase in life expectancy of 5.5 years between 2000 and 2016, representing the fastest increase since the 1960s. The type, specificity and intensity of exercise are important as hormones influence and are influenced by physical activity.
Multiple large studies have shown that the intensity of exercise has a significant positive hormonal effect. High-intensity training over 10 minutes in duration and heavy resistance training shows an exercise induced growth hormone response. Heavy resistance training also increases testosterone and DHEA while lowering cortisol levels.
Positive hormonal influences occurred over numerous studies of moderate to higher levels of activity but none at lower level exercise. This correlated to a 50% reduction in risk of functional limitations.
The type of exercise is also important with aerobic exercise and resistance training having positive effects on growth hormone and estrogen while testosterone levels showing greater improvements with resistance training. Many studies advocate heavy or moderate-intensity resistance training, including power lifting, to maximize muscular strength for functional tasks.
Specificity refers to training for the specific functional task. Walking, standing exercises using multiple modalities, core strengthening, mobility and stability exercises are all forms of targeted areas for improved functional abilities.
Exercise modalities such as swimming and cycling, while excellent, for aerobic improvement are not specific to functional ability improvement.
If the above is not possible, walking four-to-seven times a week can reduce the onset of a functional disability by 50%-80% in older adults. Keeping us all as functional as possible needs only one word…MOVE!
— Robin Gaudette is the aquatics wellness coordinator at the Redmond Area Park and Recreation District. Contact her at firstname.lastname@example.org .