The swelling ranks of the 65+ population, increases in life expectancy, changing attitudes about senior fitness, and the desire to live an improved quality of life, result in an increase of boomers that walk through our doors.
Functional fitness is of particular importance when working with our older adults, since aging is accompanied by a progressive decline in multiple physiological functions, including the ability to perform daily activities. The topic of functional aging addresses this ability (or lack thereof) and is becoming more and more relevant, given the increase in people 65 and older and the disability rates in this population.
Physical activity can both influence and be influenced by hormones, depending on the type and intensity of activity, as well as the hormone’s function. Sleep and exercise are the two most powerful nonpharmacological stimuli of growth hormone (GH) secretion. Older adults consider the capacity to carry out everyday activities to be of greater concern than disease prevention. With that in mind, when we are working with our older adults, we are focused on increasing functional ability and performance, with an ultimate goal of improving quality of life. The effect that exercise has on hormones can offset some age-related hormonal changes and, therefore, minimize some of the functional decline.
Multiple studies show that exercise intensity is a key factor in the hormone response to physical activity among older adults. Godfrey & Blazevich (2004) found that a significant exercise-induced GH response was achieved with high intensity interval training and heavy resistance training, but only after a certain amount of time. For example, HIT training above lactate threshold resulted in a GH response only after 10 minutes, and sprints were more effective at 30 seconds versus 6 seconds. This same study showed that, in older adults, acute bouts of heavy resistance training resulted in large-scale and immediate increases in testosterone, DHEA and GH and a decrease in cortisol (Godfrey & Blazevich 2004). Low-intensity exercise, in comparison, had no significant GH response in older adults.
Weltman et al. (2006) also reported that only exercise intensities above lactate threshold elevated GH output in older adults. Similarly, Paterson & Warburton (2010) found that moderate to higher levels of activity, but not low levels, correlated to a 50% reduction in risk of functional limitation and disability. In Kemmler et al. (2003), DHEA-sulfate levels in early postmenopausal females were higher immediately after a combined endurance and strength training session and were still higher 2 hours later. (DHEA becomes DHEA-S in the adrenal glands and the liver.)
Although intensity has the highest effect on hormone output, exercise type and specificity also play crucial roles in functional performance and ability. Resistance training and aerobic exercise have positive effects on GH and estrogen and both long-term and short-term aerobic exercise could increase estrogen levels in older adults with very low fitness levels. Testosterone levels, however, appeared to be affected more by resistance training.
The bottom line is, if you are interested in increasing functional ability and performance and maintaining a high level of quality of life, make sure you are incorporating heavy resistance training and high intensity interval training into your workout routine.