Post by carruthersjam on Mar 9, 2008 4:58:37 GMT -8
The below may be of interest:
Elderly muscles benefit from amino acid supplements
www.nutraingredients.com/news/ng.asp?n=83764&m=1NIE306&c=yuuexnwhvbomuyw
06-Mar-2008 - Supplementing the diet of elderly people with the full set of
essential amino acids can boost their lean body mass, strength and physical
function, according to a new study.
The small study, with only 12 volunteers, challenges previous studies that
showed no benefits, and highlights the potential benefits of amino acid
supplements for this growing age group at risk of gradual decline in muscle
mass,
strength and function.
World population is expected to increase to 9.1bn by 2050 - up from 6.5bn in
2005; and 21 per cent of people will be over the age of 60 in 2050, compared
to 10 per cent in 2000.
"Previous studies in elderly subjects have shown that provision of dietary
supplements has not been effective in improving _lean body mass_
(javascript:KeywordSearch('KEYWORDS=lean+body+mass&period=all&inner=1')
.
However,
ingestion of nutritionally balanced supplements has often been found to reduce
the
caloric intake of the rest of the food eaten in the day by an amount
equivalent to the calories supplied in the supplement," explained the authors,
led
by Elisabet Borsheim from University of Texas Medical Branch.
"Therefore a dietary supplement in the elderly would be more appropriately
considered as a dietary substitute."
The study is published online ahead of print in the journal Clinical
Nutrition.
Borsheim and co-workers recruited seven female and five male
glucose-intolerant subjects with an average age of 67 and assigned them to
receive a daily
amino acid supplement (22 grams) between meals for 16 weeks. The supplement
contained histidine, isoleucine, leucine, lysine, methionine, phenylalanine,
threonine, valine, and arginine
"The composition of the mixture of essential _amino acids_
(javascript:KeywordSearch('KEYWORDS=amino+acids&period=all&inner=1') (EAA)
was designed to
be maximally effective in stimulating muscle protein synthesis in the
elderly," explained the researchers.
After 12 weeks an increase in lean body mass (LBM) of 1.14 kg was recorded,
while this decreased slightly to 0.6 kg after 16 weeks, compared to LBM
measured at the start of the study (baseline).
Moreover, strength in the legs increased by an average of 22 per cent after
16 weeks, from a baseline value of 127.5 kg. Borsheim also notes an
improvement in measures of walking speed, including the usual gait speed, timed
5-step
test, and timed floor-transfer test.
"Generally, inclusion of a placebo group is preferred. However, we assumed
that no improvement in lean body mass, muscle strength and physical function
would have occurred over 16 weeks without intervention. Thus, the individual
pre-intervention data were used as control," stated the researchers.
"In summary, the results of the present study showed improvements of lean
body mass, muscle strength and physical function in response to supplementation
of the diet with EAA plus arginine in glucose intolerant elderly subjects,"
they added.
"We propose that over a more prolonged time, exercise will amplify the
beneficial effects of EAA supplementation on lean body mass, strength, and
muscle
function in both healthy and insulin-resistant elderly. This remains to be
studied," they concluded....
=====================
Skeletal muscle protein anabolic response to resistance exercise and
essential amino acids is delayed with aging
J Appl Physiol (March 6, 2008). doi:10.1152/japplphysiol.00021.2008
Resistance exercise is a useful intervention to
prevent sarcopenia, however, the muscle protein synthesis (MPS) response to
resistance exercise is less in elderly when compared with young subjects. On
the
other hand, essential amino acids (EAA) increase MPS equally in both young and
old subjects when sufficient EAA is ingested.
We hypothesized that EAA
ingestion following a bout of resistance exercise would stimulate anabolic
signaling
and MPS similarly between young and old men. Each subject ingested 20g of
EAA 1hr following leg resistance exercise. Muscle biopsies were obtained
before, 1, 3, and 6hr post-exercise to measure the rate of MPS and signaling
pathways which regulate translation initiation. MPS increased early in young
(1-3hr
post-exercise) and later in old (3-6hr post-exercise). At 1hr post-exercise,
ERK1/2 and MNK1 phosphorylation increased and eIF2 phosphorylation decreased
only in the young. mTOR signaling (mTOR, S6K1, 4E-BP1, eEF2) was similar between
groups at all time points but MNK1 phosphorylation was lower at 3hr and AMPK
phosphorylation was higher in old 1-3hr post-exercise.
We conclude that the
acute MPS response after resistance exercise and EAA ingestion is similar
between
young and old men, however, the response is delayed with aging. Unresponsive
ERK1/2 signaling and AMPK activation in old muscle may be playing a role in
the delayed activation of muscle protein synthesis. Notwithstanding, the
combination of resistance exercise and EAA ingestion should be a useful
strategy to
combat sarcopenia.
Elderly muscles benefit from amino acid supplements
www.nutraingredients.com/news/ng.asp?n=83764&m=1NIE306&c=yuuexnwhvbomuyw
06-Mar-2008 - Supplementing the diet of elderly people with the full set of
essential amino acids can boost their lean body mass, strength and physical
function, according to a new study.
The small study, with only 12 volunteers, challenges previous studies that
showed no benefits, and highlights the potential benefits of amino acid
supplements for this growing age group at risk of gradual decline in muscle
mass,
strength and function.
World population is expected to increase to 9.1bn by 2050 - up from 6.5bn in
2005; and 21 per cent of people will be over the age of 60 in 2050, compared
to 10 per cent in 2000.
"Previous studies in elderly subjects have shown that provision of dietary
supplements has not been effective in improving _lean body mass_
(javascript:KeywordSearch('KEYWORDS=lean+body+mass&period=all&inner=1')
.However,
ingestion of nutritionally balanced supplements has often been found to reduce
the
caloric intake of the rest of the food eaten in the day by an amount
equivalent to the calories supplied in the supplement," explained the authors,
led
by Elisabet Borsheim from University of Texas Medical Branch.
"Therefore a dietary supplement in the elderly would be more appropriately
considered as a dietary substitute."
The study is published online ahead of print in the journal Clinical
Nutrition.
Borsheim and co-workers recruited seven female and five male
glucose-intolerant subjects with an average age of 67 and assigned them to
receive a daily
amino acid supplement (22 grams) between meals for 16 weeks. The supplement
contained histidine, isoleucine, leucine, lysine, methionine, phenylalanine,
threonine, valine, and arginine
"The composition of the mixture of essential _amino acids_
(javascript:KeywordSearch('KEYWORDS=amino+acids&period=all&inner=1')
(EAA)was designed to
be maximally effective in stimulating muscle protein synthesis in the
elderly," explained the researchers.
After 12 weeks an increase in lean body mass (LBM) of 1.14 kg was recorded,
while this decreased slightly to 0.6 kg after 16 weeks, compared to LBM
measured at the start of the study (baseline).
Moreover, strength in the legs increased by an average of 22 per cent after
16 weeks, from a baseline value of 127.5 kg. Borsheim also notes an
improvement in measures of walking speed, including the usual gait speed, timed
5-step
test, and timed floor-transfer test.
"Generally, inclusion of a placebo group is preferred. However, we assumed
that no improvement in lean body mass, muscle strength and physical function
would have occurred over 16 weeks without intervention. Thus, the individual
pre-intervention data were used as control," stated the researchers.
"In summary, the results of the present study showed improvements of lean
body mass, muscle strength and physical function in response to supplementation
of the diet with EAA plus arginine in glucose intolerant elderly subjects,"
they added.
"We propose that over a more prolonged time, exercise will amplify the
beneficial effects of EAA supplementation on lean body mass, strength, and
muscle
function in both healthy and insulin-resistant elderly. This remains to be
studied," they concluded....
=====================
Skeletal muscle protein anabolic response to resistance exercise and
essential amino acids is delayed with aging
J Appl Physiol (March 6, 2008). doi:10.1152/japplphysiol.00021.2008
Resistance exercise is a useful intervention to
prevent sarcopenia, however, the muscle protein synthesis (MPS) response to
resistance exercise is less in elderly when compared with young subjects. On
the
other hand, essential amino acids (EAA) increase MPS equally in both young and
old subjects when sufficient EAA is ingested.
We hypothesized that EAA
ingestion following a bout of resistance exercise would stimulate anabolic
signaling
and MPS similarly between young and old men. Each subject ingested 20g of
EAA 1hr following leg resistance exercise. Muscle biopsies were obtained
before, 1, 3, and 6hr post-exercise to measure the rate of MPS and signaling
pathways which regulate translation initiation. MPS increased early in young
(1-3hr
post-exercise) and later in old (3-6hr post-exercise). At 1hr post-exercise,
ERK1/2 and MNK1 phosphorylation increased and eIF2 phosphorylation decreased
only in the young. mTOR signaling (mTOR, S6K1, 4E-BP1, eEF2) was similar between
groups at all time points but MNK1 phosphorylation was lower at 3hr and AMPK
phosphorylation was higher in old 1-3hr post-exercise.
We conclude that the
acute MPS response after resistance exercise and EAA ingestion is similar
between
young and old men, however, the response is delayed with aging. Unresponsive
ERK1/2 signaling and AMPK activation in old muscle may be playing a role in
the delayed activation of muscle protein synthesis. Notwithstanding, the
combination of resistance exercise and EAA ingestion should be a useful
strategy to
combat sarcopenia.