Post by carruthersjam on Jul 19, 2008 9:43:38 GMT -8
The aging neuromuscular system in men and women still responds to
strength training - NSCA Conference, July 9-12, Las Vegas, USA
Keijo Häkkinen
Decreases in muscle strength and power during aging
Muscle strength and power decrease with increasing age accompanied
with a steeper strength decline at the onset of the sixth decade in
both genders. The decrease in maximal strength from the age of 30 to
the age of 80 years can be as large as 30 to 40 %. However, it may be
different between different muscle groups, and e.g. in the proximal
muscles of the lower extremities it seems to be greater than that of
the upper extremities (2)….
The decrease in maximal strength is related to a great extent to the
reduction in muscle mass both in men and women, since aging is
associated with alterations in hormone balance, especially with
decreased androgen levels, and often also with a decline in the
amount of physical activities and especially with a decrease in the
intensity of these activities. The decline in muscle mass is due to
both a reduction in the size of individual muscle fibres, especially
of type II fibres, and a loss of individual fibres (17). A decrease
in maximal strength might also be in part due to a decrease in
maximal voluntary neural input to the muscles and/or changes
in "qualitative" characteristics of the muscle tissue (4)…….
Aging leads also to great worsening in explosive force production
whether recorded during dynamic actions by power or by the shapes of
the force-time curves. Actually, the age-related decrease in
explosive strength/power seems to be even larger than that observed
in maximal strength (3,4).
Age-related strength and power decreases in master athletes
Maximal strength and power decline with aging also in master athletes
e.g. throwers (shot put, hammer, discus) who have carried out
strength training over several decades. However, "lifelong" strength
training seems to minimize age-related strength decreases at all
ages, since male master athletes at the age of 75 years showed higher
absolute strength values than untrained men at the age of 40 years
both in the lower and upper extremity extensors (19). the lower
(5,6,7) and upper extremities (20). The increase in muscle CSA during
strength training comes primarily from the increase in size of
individual muscle fibres of both type I and II, and to some degree
from the increase in non-contractile connective tissue between the
fibres, probably with no addition in fibre number. Strength training-
induced muscle hypertrophy in older men and women seems to take place
both in subtype IIa and IIb fibres (6,7). High tension of a muscle
for a sufficient duration somehow provides the signal for increased
uptake of amino acids and enhanced synthesis of contractile proteins.
The repeated process of damage and repair during and between training
sessions may result in an overshoot of protein synthesis.
In addition, type II subtype transformation going from type IIb to
IIab to IIa has been previously observed in younger (13) and older
men (6) but not necessarily in older women (7).
Neuromuscular adaptations during strength and power training in
master athletes
Muscle CSA of the leg and arm extensors decrease with increasing age
also among master throwers (19). However, these athletes showed
almost similar CSAs at the age of 75 years compared to untrained men
at the age of 40 years. This no doubt demonstrates the high
trainability of muscle mass even at older ages. Another recent study
(1) showed that incorporating weight training exercises into the
overall training for 20 weeks led to improvements in maximal and
explosive strength in world-class master sprinters (52-78 years).
Part of the explanation for the substantial improvements in muscular
strength may be due to the specific form of strength training used,
in which heavy resistance exercises were combined with explosive
types of weight training and plyometric exercises. The large strength
gains may also reflect successful periodization of training to
maintain overall training loading within the normal physiological
range. These older athletes were able to produce higher ground forces
with shorter contact times in response to the training program,
leading to an increase in the rate of force development.
Conclusions
We do have a large amount of scientific evidence to conclude that the
aging neuromuscular system in men and women remarkably responds to
strength training. Strength training should "always" be recommended
as an important part of an overall physical training program to
maintain functional capacity of middle-aged and older persons of both
genders at as high a level as possible for as long as possible.
Strength and the ability of the leg extensor muscles to develop force
rapidly contribute to several tasks of daily life. The benefits of
maintaining or improving strength and power in aging people include
correction of gait disturbances, prevention of falls, improved stair
climbing and walking, and increased mobility, improved performance of
activities of daily living, increased capacity of independent living
and delayed threshold of dependency.
Proper strength training of aging men and women can be utilized as a
preventive, therapeutic, and rehabilitative tool to optimize
neuromuscular function and enhance performance. Strength training is
no doubt important for master athletes and the programs should pay
proper attention not only to maximal strength but also to power
training of important muscle groups to optimize the athletes'
performance in their event.
strength training - NSCA Conference, July 9-12, Las Vegas, USA
Keijo Häkkinen
Decreases in muscle strength and power during aging
Muscle strength and power decrease with increasing age accompanied
with a steeper strength decline at the onset of the sixth decade in
both genders. The decrease in maximal strength from the age of 30 to
the age of 80 years can be as large as 30 to 40 %. However, it may be
different between different muscle groups, and e.g. in the proximal
muscles of the lower extremities it seems to be greater than that of
the upper extremities (2)….
The decrease in maximal strength is related to a great extent to the
reduction in muscle mass both in men and women, since aging is
associated with alterations in hormone balance, especially with
decreased androgen levels, and often also with a decline in the
amount of physical activities and especially with a decrease in the
intensity of these activities. The decline in muscle mass is due to
both a reduction in the size of individual muscle fibres, especially
of type II fibres, and a loss of individual fibres (17). A decrease
in maximal strength might also be in part due to a decrease in
maximal voluntary neural input to the muscles and/or changes
in "qualitative" characteristics of the muscle tissue (4)…….
Aging leads also to great worsening in explosive force production
whether recorded during dynamic actions by power or by the shapes of
the force-time curves. Actually, the age-related decrease in
explosive strength/power seems to be even larger than that observed
in maximal strength (3,4).
Age-related strength and power decreases in master athletes
Maximal strength and power decline with aging also in master athletes
e.g. throwers (shot put, hammer, discus) who have carried out
strength training over several decades. However, "lifelong" strength
training seems to minimize age-related strength decreases at all
ages, since male master athletes at the age of 75 years showed higher
absolute strength values than untrained men at the age of 40 years
both in the lower and upper extremity extensors (19). the lower
(5,6,7) and upper extremities (20). The increase in muscle CSA during
strength training comes primarily from the increase in size of
individual muscle fibres of both type I and II, and to some degree
from the increase in non-contractile connective tissue between the
fibres, probably with no addition in fibre number. Strength training-
induced muscle hypertrophy in older men and women seems to take place
both in subtype IIa and IIb fibres (6,7). High tension of a muscle
for a sufficient duration somehow provides the signal for increased
uptake of amino acids and enhanced synthesis of contractile proteins.
The repeated process of damage and repair during and between training
sessions may result in an overshoot of protein synthesis.
In addition, type II subtype transformation going from type IIb to
IIab to IIa has been previously observed in younger (13) and older
men (6) but not necessarily in older women (7).
Neuromuscular adaptations during strength and power training in
master athletes
Muscle CSA of the leg and arm extensors decrease with increasing age
also among master throwers (19). However, these athletes showed
almost similar CSAs at the age of 75 years compared to untrained men
at the age of 40 years. This no doubt demonstrates the high
trainability of muscle mass even at older ages. Another recent study
(1) showed that incorporating weight training exercises into the
overall training for 20 weeks led to improvements in maximal and
explosive strength in world-class master sprinters (52-78 years).
Part of the explanation for the substantial improvements in muscular
strength may be due to the specific form of strength training used,
in which heavy resistance exercises were combined with explosive
types of weight training and plyometric exercises. The large strength
gains may also reflect successful periodization of training to
maintain overall training loading within the normal physiological
range. These older athletes were able to produce higher ground forces
with shorter contact times in response to the training program,
leading to an increase in the rate of force development.
Conclusions
We do have a large amount of scientific evidence to conclude that the
aging neuromuscular system in men and women remarkably responds to
strength training. Strength training should "always" be recommended
as an important part of an overall physical training program to
maintain functional capacity of middle-aged and older persons of both
genders at as high a level as possible for as long as possible.
Strength and the ability of the leg extensor muscles to develop force
rapidly contribute to several tasks of daily life. The benefits of
maintaining or improving strength and power in aging people include
correction of gait disturbances, prevention of falls, improved stair
climbing and walking, and increased mobility, improved performance of
activities of daily living, increased capacity of independent living
and delayed threshold of dependency.
Proper strength training of aging men and women can be utilized as a
preventive, therapeutic, and rehabilitative tool to optimize
neuromuscular function and enhance performance. Strength training is
no doubt important for master athletes and the programs should pay
proper attention not only to maximal strength but also to power
training of important muscle groups to optimize the athletes'
performance in their event.