Aging of heart, blood vessels, chest, lungs and brain is significantly retarded with aerobic
A program of progressive resistance training (PRT) that reduced age-dependent loss of skeletal muscle mass and strength was discussed in the previous blog. Three other types of exercises of considerable importance are 1) aerobic, 2) stretch and 3) balance exercises, and together with PRT, provide a comprehensive exercise program for the older adult. As with PRT, these additional 3 exercises have been validated in clinical trials to retard specific age changes and enhance physical function. For that reason, this blog will focus on the benefits of aerobic and stretch exercises and define how each should be performed to achieve maximal health results. Balance exercises improve different age-related deficits and consequently will be discussed separately in another blog.
Age changes prevented/slowed with aerobic and stretch exercises
One’s ability to engage in physical activity or activities above rest e.g. climbing stairs, shopping, catching a bus, running on the track, requires enhanced coordinated efforts from many organ-systems. Consider the most noteworthy changes:
What happens in the heart
a) there is a stronger and more forceful heart beat to assure that more blood is pumped to key organs e.g. skeletal muscles, lungs and also the heart;
What happens in the blood vessels
b) there is an improve compliance (flexibility) of blood vessels to keep blood pressure adequate for delivery of elevated levels of oxygen and removal of carbon dioxide and other waste products;
What happens in the lungs
c) there is an increase the rate and depth of each breath by forceful contraction of the chest, diaphragm and abdominal muscles to capture more oxygen and expel more carbon dioxide;
What happens in the leg muscles
d) there are more rapid and forceful contractions/relaxations of mainly the large skeletal muscles of the legs.
Peak performance declines with age but more so with a sedentary lifestyle
This multiplicity of events, at its peak performance level for any one person, is referred to as maximal oxygen consumption. Since maximal oxygen consumption can be measured fairly accurately, it has been for decades a popular number for scientists to assess. It basically represents the level of physical fitness of an individual. Thus there is a considerable amount of information defining the change in maximal oxygen consumption (or fitness) over time. In particular, fitness declines with age in everyone but significantly less so in older adults engaged in an aerobic program for most of their adult life. Regrettably and because of this, elderly with a sedentary lifestyle will experience a dramatic inability to engage comfortably in all physically activities above rest. Physical activity will be cut short by rapid onset of fatigue.
Without chronic aerobic exercise, heart, blood vessels, lungs and leg muscles slowly fail
In the absence of aerobic exercise, an age-related decline in VO2max occurs for several reasons: both the heart and large blood vessels (carotids, aorta) become less compliant e.g. stiffer over time. This causes the heart to work harder even at rest. Additionally, the small blood vessels with time lose their ability to produce an essential vasodilator (EDRF) that had assured increased blood flow when younger. Without EDRF, key organs (heart, lungs, brain, skeletal muscles) are deprived of requisite oxygen and nutrients and hence tissues/organs cannot handle the demands inherent in physical activity. The lungs and chest also become harder to inflate and deflate due to factors such as loss of chest and lung flexibility but also muscle weakness (dynapenia). These are guaranteed age-associated changes in the absence of aerobic exercises.
Proven benefits of aerobic exercise
Unlike resistance exercises, the number of older adults that participate regularly in aerobic exercises is significantly greater (approximately 40% age 65-74, 30% 74-84 and 20% >85*) and this is a good thing. However, considering the multitude of benefits, this degree of participation remains disappointing.
Aerobic exercises include activities such as jogging/running (outside or treadmill), cycling (outside or stationary), swimming, dancing, and walking. Results of literally thousands of interventional clinical trials, observational and epidemiological studies point to an abundance of benefits of regular aerobic exercise. All the benefits listed have been documented numerous times. Benefits of regular aerobic exercise are:
Blood vessel transport blood more easily
1) reduction in age-dependent stiffening of major arteries allowing greater capacity of arteries to stretch and secondarily to reduce the workload on the heart; lower resting heart rate promoting more efficient heart pumping
Exchange of nutrients, gases and waste products is more efficient
2) tissues/organs are healthier due to better flow of oxygen in and waste products out resulting in less inflammation and cellular damage; especially beneficial to the brain leading to improved cognition, reduced risk of mild cognitive impairment, depression, anxiety
Control of blood sugar is improved; fats and “bad” cholesterol are lowered
3) metabolic benefits of improved blood sugar control, reduction in body fat, favorable lipid profile with low levels of free fatty acids and higher levels of HDL (“good cholesterol”), weight maintenance or loss
More energy for all activities
4) decrease in fatigue (the older adult tires less easily, remains physically active for longer periods of time)
Reduced levels of stress
5) increase in ability to handle stress ( the older adult exhibits better outcomes following surgery e.g. shorter hospital stay, faster recovery)
Reduction in risk for many diseases
6) reduction in risk for diseases including cardiovascular disease, type 2 diabetes, Alzheimer’s disease and frailty (condition of increased weakness predicting imminent death
Assured independence and quality of life
7) increase in quality of life supporting continued independence
Aerobic exercises – how to get the most out of them
Each person should select the aerobic activity of interest. For sedentary elderly initiating a program, it is prudent to first discuss an exercise program with your physician and then to begin slowly with a progressive stepwise increase in intensity. As with PRT, the goal with aerobic exercises is to gradually do more by increasing time or energy spent. As several recent studies have shown, anti-aging health benefits are proportional to the input.
Ideally, aerobic exercises are performed five times a week for 30 minutes or more depending on the level of intensity (55-90% of a maximal heart rate or 12-and above on a perceived exertion scale given in Table 1 in PDF 1). Maximal heart rate can be calculated by multiplying one’s age by 0.7 and subtracting that number from 208. Table 2 in PDF 1 shows the required exercise duration based on intensity.
An alternative to standard aerobic exercise is high intensity interval training (HIIT)
The Mayo Clinic*** in an impressive study about 3 years ago reported that 12 weeks of high intensity interval training (HIIT) provided huge benefits for the elderly. In this study, volunteers in 2 different age groups (18-30 yrs and 65-80 yrs) performed the following: a) high intensity interval training, 3x weekly + 2x weekly of treadmill walking, b) resistance training, 2x weekly and c) sedentary period followed by combined training of moderate-intensity aerobics, 5x weekly + 4x weekly resistance training .
HIIT in this study consisted of stationary cycling for 4 minutes at > 90% maximal oxygen intake (high intensity), followed by 3 minutes reduced intensity (no resistance), followed by 4 minutes of maximal oxygen intake, followed by 3 minutes of no resistance. This was repeated two more times yielding total time investment of 25 minutes.
Benefits of HIIT
HIIT results outperformed the other two exercise protocols by providing the following:
a) highest level of improved cardio-respiratory fitness (optimal heart and lung function), increased insulin sensitivity (lower blood sugar levels), enhanced mitochondrial respiration (improved function of cells with evidence of reversal of age changes), and decreased fat-free mass (loss of body fat) in both young and older age groups.
b) similar but lesser effects were observed in groups undergoing resistance training and combined training. It is concluded that HIIT is a more effective means of reversing aging of the heart, blood vessels, chest , lungs and skeletal muscles. Thus it can substitute for vigorous exercise listed in Table 2.
Benefits of stretch exercises
Performance of stretching or flexibility exercises is the best way to:
a) improve range of motion of the joints,
b) increase agility and speed in physical activities,
c) reduce injury of muscles and joints.
In addition to the above, other benefits from adherence to a stretching protocol have been observed: lowering of blood sugar in individuals with Type 2 Diabetes, reduction in frequency and intensity of nocturnal leg cramps.
Stretching to accompany aerobic exercises
What are stretch exercises?
Stretch exercises are an excellent companion to aerobic exercises. Performance frequency for stretch exercises is under debate. Suggestions range from twice daily every days to the traditional advice of stretching before and after aerobic exercises (5 days a week). Recently, it was found that maximal benefit is achieved with stretching after a session of aerobic exercise and in this case, a warm-up (exercising at a low intensity) prior the aerobic exercise session is recommended to replace the stretch exercises. There are two types of stretch exercises: static and fluid (dynamic). Static stretching is maintaining a slow and controlled continuous tension to a muscle group(s) while fluid stretching requires tension on specific muscle groups while taking them through a full range of motion.
How to get the most out of stretch exercises
Total stretching time with a variety of stretches is the important determinant that improves range of motion and reduces injury. This is more influential than the length of time a stretch is held or the number of repetitions. Optimal stretch time per muscle group is generally 30 seconds. As with other exercises, the gain in benefit (range of motion, flexibility etc) with stretching declines over time when the protocol is stopped.
There are many static and fluid stretches for both upper and lower body muscles. The following videos provides excellent examples to incorporate into a stretch protocol following an aerobic workout.
Videos demonstrating stretch exercises
* Data from surveys and household interviews (2013-2015) reported by Centers for Disease Control and Prevention September 23, 2016 / 65(37);1019
** Borg GA. Psychophysical bases of perceived exertion. Med Sci Sports Exerc 14:377-381, 1982.
*** Robinson et al., Enhanced Protein Translation Underlies Improved Metabolic and Physical Adaptations to Different Exercise Training Modes in Young and Old Humans Cell Metabolism 25: 581–592, 2017