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Sumario
Nº 1
> Physical
Exercise
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Physical Exercise and "Biological Age"
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Prof.
Jaime Miquel
Professor of the Department of Biotechnology, University of Alicante,
Spain
Former Chief of the Experimental Pathology Branch, NASA-Ames Research
Center, Mountain View, California
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Introduccion |
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Exercise preserves some of our youthful strength,
even in old age. Cicero
According to Bortz (1), prestigious researcher of the relations
between physical exercise (P.E.), aging and health, a study performed
by the American Cancer Society on approximately one million subjects,
4,600 of which were older than 85 years, showed that P.E. has
a positive effect on longevity. Bortz also reviewed other studies,
performed in Holland and Finnland, which confirm the favorable
effects of P.E. not only on longevity but also on the expectancy
of quality of life (or functional life expectancy). This decreases
with age, in agreement with data from the USA showing that whereas
70-year old human subjects have a 60% expectancy of active life
of the remaining 20 years of total life expectancy, this percentage
of survival with good quality of life is decreased to 40% at the
age of 85 years (i.e., about 3 years in good health, or less than
one half of the probable survival time). Many studies confirm
the favorable effects of P.E.: preservation of an optimal body
weight, normal levels of blood pressure, lower decline of respiratory
and circulatory function and of the senescent loss of muscle mass
and bone density, etc. Therefore, Bortz concludes that P.E. increases
the chances of preserving the quality of life of the aged.
Moreover, according to Rosenfeld (2), muscle strenght, aerobic
competence and heart function are preserved at higher levels in
the subjects who practice exercise than in the sedentary controls.
This author also notes that P.E. helps to maintain more normal
levels of blood pressure, glucose and cholesterol. These positive
effects are also confirmed by research on very longeve populations
of the world, the members of which, besides consuming a frugal
diet (which does not result in nutritional deficiencies) are physically
active throughout their lives (2).
As we willl comment below, many studies support the hypothesis
that the subjects who are physically active preserve some parameters
of their biological (or functional age) at more youthful levels
than those shown by non-exercising subjects. It is worth-noting
that the concept of biological age has already shown its usefulness
in the radiation biology and biogerontology fields as well as
in the NASA research that suggests that the astronauts may suffer
"premature aging", because of their exposure to "weightlessnes"
(or microgavity) during space flight.
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Concept
of biological age and biomarkers |
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It is well known that
the molecular and cellular disorganization and the decrease in physiological
performance associated with aging do not proceed at the same rate
in all members of a population of the same chronológical
age (3-6). This justifies the introduction of the concept of biological
(or functional) age, as well as of biomarkers or parameters, the
determination of which reveals the level of senescence suffered
by the physiological systems of an individual. Thus it is possible
to assess the effects on aging of the diverse life styles and the
functional loss suffered by the phyisiological systems of a subject,
in order to apply "custom-made" individualized treatments
of preventive geriatrics (7,8).
Since the passage of time is linked to a great number of changes
at all levels of biological organization, it is easy to select batteries
of biochemical, physiological and psychological parameters that
change with age and can be subjected to statistical analysis in
order to reveal the relations between biological age, chronological
age, health loss and longevity expectancy. The most complete investigation
was performed by Borkan and Norris (4), on over one thousand men,
in the longitudinal study on human aging of the Gerontological Center
of Baltimore. This study suggests that it is not correct to define
an integrated biological age, since the data show that a subject
can be biologically older in some physiological systems than in
others.
The retrospective analysis of the Baltimore data also showed that
the subjects presenting certain parameters "more aged"
than those found in the majority of the subjects of the same chronological
age had a shorter life expectancy. Thus, according to Borkan and
Norris, the following parameters showed significant differences
between the longeve subjects and those dying prematurely: respiratory
function, systolic arterial pressure and reaction times. As previously
noted (7), the interesting results of the Baltimore study suggest
that it is already possible to practice a preventive geriatric medicine
based on the detection of the parameters that are prematurely aged
(risk factors) and the prompt application of measures to retard
the involution of the systems that can be considered the Achilles
heel of each individual. |
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Favorable
effects of physical exercise on the parameters of biologicals age |
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The published work suggests
that P.E. protects against the age-related functional changes of
the above mentioned parameters of biological age, or biomarkers.
As regards the respiratory function, exercise improves lung ventilation
and the inspiración volume (9). Exercise also contributes
to "keeping in shape", which is accompanied by a favorable
efect on reaction time (9). Moreover, according to the data reviewed
by Marcos Becerro (10), physical exercise has favorable effects
on another important biomarker of premature aging, i.e., hypertension.
More specifically, this author comments that as regards the action
of chronic exercise, i.e., that carried out by repeated training
sessions, a great proportion of the published work shows a decrease
of both systolic and diastolic blood pressure (10). Likewise, according
to Hagberg (11), two thirds of the subjects who suffer systolic
hypertension and perform P.E. show a 7 % decrease of their blood
pressure values, which suggests that exercise may be useful for
the treatment of hypertension in the aged, in agreemente with the
classic study of Tipton (12).
In addition to the effects of P.E. on the above mentioned biomarkers,
which are predictors of life span, exercise also appears to preserve
other parameters of biological age that have a marked efect on the
active or functional longevity and quality of life of the elderly
persons. Among these favorable efects, stands out the preservation
of muscle mass and strenght, which suffer a senescent decline because
of the progressive involution linked to normal differentiated-cell
aging (13, 14) as well as to the disuse atrophy caused by a sedentary
life style. In their excellent monograph, Gutmann y Hanzlíková
(15) summarize the favorable action of exercise on the age related
loss of muscle function in the following words: "The trained
muscles show the effects of neural activation, which allows a faster
recovery process and a better coordination of the muscle groups".
In addition, these authors also comment on the protective action
against disuse atrophy of a constant functional activity. As an
example, they point out that the muscles forced to a rhytmic activity
in the respiratory process do not show a marked decrease in the
speed of contraction (15).
The gerontological importance of disuse atrophy and its prevention
is also confirmed by NASA research on the "premature aging"
of the musculo-skeletic system during spaceflight (Miquel and Souza,
16). Indeed there is a loss of calcium from the bones of the astronauts,
who owing to the lack of the stimulus of normal Earth gravity suffer,
during space travel, a process similar to the osteoporosis shown
by many aged persons (17). Presently, in order to prevent this microgravity-linked
bone loss, the American astronautas and Russian cosmonauts practice
during space flight certain P.E. activities such as fixed-bycicle
riding (17). Other biomarkers that decline with age and can improve
with exercise are related to good mental health (Oña Sicilia,
18; Blain et al., 19) and immune function, the competence of which
is closely related to longevity expectancy (De la Fuente et al.,
20; De la Fuente and Miquel, 21).
It is very important that P.E. has a protective action on one of
the main causes of mortality in the industrialized countries, i.e.
coronary disease (22). Thus, in agreement with the favorable effects
of P.E. on blood pressure, the studies of Morris (reviewed in ref.
23), comparing the frequency of coronary disease in drivers and
ticket-controllers of the London bus lines, as well as in mailmen
in comparison to sedentary office workers, support the view that
"moderately vigorous" or "vigorous" exercise
protects against such disease in subjects 35 to 64 year old. Therefore,
Paffenberger et al., (23) point out that a great number of recent
studies on men and women of different etnic and professional groups,
confirm that exercise protects against coronary disease and premature
mortality. |
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Conclusions:
Exercise is a key factor of a life style that contributes to functional
longevity |
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The reviewed work supports
the opinion that the regular practice of exercise increases the
chances of gaining a desirable longevity with preservation of quality
of life. Thus, in the words of Gutmann and Hanzlíkova (15):
"It has been demonstrated that the functional decline that
occurs with age can be delayed in persons who are usually active.
Physical activity contributes to achieve a 'succesful aging', i.e.,
a process of aging in which the functional competence is preserved
and used more effectively than in the inactive persons. Probably,
experiments on animals and longitudinal and transversal studies
on human subjects will prove in the future that physical exercise
leads to both an increase in longevity (within the genetic limits)
and a decreased rate of aging". Moreover, according to Zaragoza
(9), exercise has important effects on life style and health, since
its usual practice decreases the incidence of diseases, improves
work capacity, decreases stress, contributes to a more satisfying
sleep and provides the subjective perception (supported by objective
data) that one enjoys a better health. And, likewise, on the basis
of his own research, Bortz (1) concludes that exercise is essential
to enjoy a full life.
As a complement to the work of the experts in sports medicine, many
cardiologists and gerontologists investigate the role of P.E. as
one of the key factors of a life style that delays or prevents some
of the pathological processes associated with aging. This concept
agrees with the data of Paffenberger et al.(24) on the effects of
changes in the life style of 10,269 former students of the University
of Harvard, ranging in age from 45 to 84 years at the start of the
study, in 1977. This study showed that the decreased mortality risk
resulting from the improvement in two important factors of the life
style during the period of the study (1977-1985) was as follows:
leaving smoking: 41% decrease in mortality; practice of a relatively
vigorous sport activity: 23% decrease in mortality.
Another life style factor that is essential to reach longevity with
health is an adequate nutrition, which, in addition to exercise,
helps to preserve the immune system functions (De la Fuente, 25;
Miquel and González-Gross, 26). Exercise can also retard
aging due to its action on body weight. According to Skelton and
Skelton (27), since during thousands of years of fasting and scarce
nutrition the human body has adapted to store nutrients, the present
combination of sedentarism and a calory-rich diet represents a double
load on physiological systems unprepared to cope with it. Therefore,
the body is unable to get rid of the excessive calories and has
to store them. This results in overweight, with its negative consequences
for health and longevity.
From a practical, health-related viewpoint Fraser and Shavlik (28)
conclude that a difference of 10 years in life expectancy at the
age of 30 is the probable result of a life style that includes an
adequate nutrition (not leading to nutritional deficiencies or overweight),
not smoking, and the regular practice of physical exercise. |
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Summary |
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A critical review of
the literature supports the concept that physical exercise is a
key factor of a life style that has a favorable effect on functional
longevity, protecting the body against several degenerative diseases
associated with aging. More especifically, the data suggest that
the regular practice of physical exercise has a "rejuvenating"
effect on parameters of biological age that predict the probable
longevity with preserved physiological functions and resulting quality
of life.
The "anti-aging" effect of exercise is mainly observed
as regards its influence on the age-related changes that occur with
the passage of time in cardio-respiratory performance and systolic
blood pressure, parameters that, according to the studies on biological
age of the National Institute on Aging, of the USA, may be quite
useful as predictors of life expectancy.
The protection afforded by physical exercise on other degenerative
processes often linked to aging, such as bone calcium loss and decrease
in muscle mass and strength may help to preserve "more youthful"
values of key biomarkers of aging, with favorable effects on health
and quality of life of the elderly populations.
Key words: Aging, biological age, functional age, biomarkers, physical
exercise. |
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References |
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- Bortz, W.M.: We Live Too Short. Bantam Books, New York, 1991,
pp. 217-233.
- Rosenfeld, A.: Prolongevity, Editor: Alfred A. Knopf, New
York, 1985, pp. 228.
- Hollingsworth, J.W. et al.: Correlation between tests of aging
in Hiroshima subjects: an attempt to define "physiologic
age". Yale Biol. Med. 38: 11-26, 1965.
- Borkan, A. y Norris, A.H.: Asessment of biological age using
a profile of physical parameters. J. Gerontol. 35: 177-184,
1980.
- Benfante, R.et al.: Biological and social predictors of health
in an aging cohort. J. Chron. Dis .38: 385-395, 1985.
- Soler, A. et al.: Biograma: instrumento de análisis
de edad biológica en grupos poblacionales diversos. Geriatrika
8: 3-9, 1992.
- Miquel J.: Envejecimiento, edad biológica y farmacología
preventiva. Pharmaklinik 5: 279-286, 1988.
- Miquel, J.: Causas y prevención del envejecimiento
prematuro. Geriatrika 10: 297-301, 1994.
- Zaragoza, J.R.: Una Vida Larga y Sana, Planeta, Barcelona,
1990: p. 174.
- Marcos Becerro, J.F.: La hipertensión en los ancianos.
En: La Salud y la Actividad Física en las Personas. Mayores.
Editor: J.F. Marcos Becerro et al., Vol. 1, 1995, pp. 260-261.
- Hagberg, J.M.: Effect of exercise training in 60-90 year-old
persons with essential hypertension. Am. J. Cardiol. 64: 348-353,
1989.
- Tipton, C.M .et al., Influence of exercise intensity, age
and medication on resting blood pressure of SHP populations.
J. Appl. Physiol. 55: 1305-1310, 1983.
- Miquel, J. y Fleming, J.E.: Theoretical and experimental support
for an oxygen radical-mitochondrial hypothesis of cell aging.
En: Free Radicals, Aging and Degenerative Diseases. Editors:
J.E. Johnson, Jr., R. Walford, D. Harman y J. Miquel. New York,
Alan R. Liss, 1986, pp. 51-74.
- Miquel, J.: An update on the oxygen stress-mitochondrial mutation
theory of aging: genetic and evolutionary implications. Exp.
Gerontol. 33: 113-126, 1998.
- Gutmann, E. y Hanzlíková, V.: Age Changes in
the Neuromuscular System. Scientechnica Ltd., Bristol, 1972,
pp. 142-168.
- Miquel, J. y Souza, K.A.: An Overview of Gravitational Physiology,
NASA Tech. Memorandum 102849, 1991, pp. 1-56.
- Miquel, J. y Rubies, J:. Similarities between normal aging
and the "microgravity-hypokinesia" syndrome. En: Aerospace
Research in Biology and Medicine. Editores: J. Oró y
J. Miquel. Fundació "la Caixa", Barcelona 1987,
pp. 149-158.
- Oña Sicilia, A.: Aspectos psicológicos del ejercicio
de los mayores. En: La Salud y la Actividad Física en
las Personas Mayores. Editor: J.F. Marcos Becerro y cols., 1995,
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- Blain, H.et al.: (The preventive effects of physical activity
in the elderly).Presse Med. 29: 1240-1248, 2000.
- De la Fuente, M.et al.: Efecto del ejercicio físico
sobre la respuesta inmune en jóvenes de vida sedentaria.
Invest. Ed. Física y Deporte 6: 30-41, 1989.
- De la Fuente, M. y Miquel, J.: Efecto protector de antioxidantes
tiólicos en la inmunodepresión asociada al envejecimiento.
Rev. Esp. Geriatr. Gerontol. 29: 246-251, 1994.
- Friesinger, G.C. y Ryan, T.J.: Coronary heart disease. Stable
and unstable syndromes. Cardiol. Clin. 17: 93-122, 1999.
- Paffenberger, R.S. et al.: A history of physical activity,
cardiovascular health and longevity: the scientific contributions
of Jeremy N. Morris, DSc, DPH, FRC. Int. J. Epidemiol. 30: 1184-1192,
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- Paffenbarger, R.S. et al.: The association of changes in physical-activity
level and other lifestyle
- De la Fuente M. Sistema inmunológico y deporte. Selección
11: 125-134, 2002.
- Miquel J. y González-Gross M.: ¿Podemos retrasar
el envejecimiento? Nutrición o deporte. Selección
11: 172-178, 2002.
- Skelton, N.K. y Skelton, W.P.: Medical implications of obesity.
Losing pounds, gaining years. Postgrad. Med. 92-151-156, 1992.
- Fraser.G.E. y Shavlik, D.J.: Ten years of life: is it a matter
of choice? Arch.Intern. Med. 161: 1645-1652.
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Science
