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Departments of Surgery and Anesthesiology, University of Texas Medical Branch, and Metabolism Unit, Shriners Burns Institute, Galveston, Texas 77550
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
ACKNOWLEDGEMENTS
FOOTNOTES
REFERENCES
ABSTRACT 
Tipton, Kevin D., Arny A. Ferrando, Bradley D. Williams, and
Robert R. Wolfe. Muscle protein metabolism in female swimmers after a combination of resistance and endurance exercise.
J. Appl. Physiol. 81(5):
2034-2038, 1996.
There is little known about the responses of
muscle protein metabolism in women to exercise. Furthermore, the effect
of adding resistance training to an endurance training regimen on net
protein anabolism has not been established in either men or women. The
purpose of this study was to quantify the acute effects of combined
swimming and resistance training on protein metabolism in female
swimmers by the direct measurement of muscle protein synthesis and
whole body protein degradation. Seven collegiate female swimmers were
each studied on four separate occasions with a primed constant infusion
of
ring-[13C6]phenylalanine
(Phe) to measure the fractional synthetic rate (FSR) of the posterior
deltoid and whole body protein breakdown. Measurements were made over a
5-h period at rest and after each of three randomly ordered workouts:
1) 4,600 m of intense interval swimming (SW); 2) a whole body
resistance-training workout with no swimming on that day (RW); and
3) swimming and resistance training combined (SR). Whole body protein breakdown was similar for all treatments (0.75 ± 0.04, 0.69 ± 0.03, 0.69 ± 0.02, and 0.71 ± 0.04 µmol · min
1 · kg1
for rest, RW, SW, and SR, respectively). The FSR of the posterior deltoid was significantly greater (P < 0.05) after SR (0.082 ± 0.015%/h) than at rest (0.045 ± 0.006%/h). There was no significant difference in the FSR after RW
(0.048 ± 0.004%/h) or SW (0.064 ± 0.008%/h) from rest or from
SR. These data indicate that the combination of swimming and resistance
exercise stimulates net muscle protein synthesis above resting levels
in female swimmers.
stable isotopes; fractional synthetic rate; protein synthesis; protein breakdown; deltoid muscle
INTRODUCTION EXERCISE HAS A PROFOUND EFFECT on protein turnover.
Muscle (4) and whole body protein synthesis (PS) (9, 21)
are increased during recovery from endurance exercise. Resistance
training has also been shown to increase muscle PS 50-100% above
resting levels early in recovery (3, 5) and up to 24 h after exercise
(5). Whole body protein breakdown (WBPB), measured with stable isotope tracers, is also increased by endurance exercise (19, 21). However, the
response of PS or protein degradation to combined endurance and
resistance training as utilized by most competitive swimmers has not
been determined. This is particularly relevant because resistance
training has become an integral part of the overall training regimen
for competitive swimmers. The primary purpose of adding resistance
training to a swimming training program is to improve muscle strength
and power, which have been shown to directly correlate with swimming
performance (8, 23).
Competitive swimmers train for 3-4 h/day and up to 10,000 m/day
(6, 7, 17), which leads to the cardiovascular and muscle adaptations
commonly found in other endurance athletes (12, 14-16). Endurance
performance may be improved by the addition of strength training (13).
One likely explanation for increased performance as a result of
combined resistance and endurance training (13) is increased muscle
hypertrophy and strength due to alterations in protein metabolism.
Although several studies have examined the response of whole body
protein metabolism to exercise (18-20, 24), no study has been
performed on the response of muscle PS in trained women. Furthermore,
the effect of adding resistance training to an endurance training
regimen on net protein anabolism has not been established in either men
or women. Therefore, the purpose of this study was to quantify the
acute effects of combined swimming and resistance training on protein
metabolism in female swimmers by the direct measurement of muscle PS
and whole body protein degradation. We hypothesized that muscle PS and
WBPB would 1) be greater after resistance exercise, swimming, and both combined than at rest and
2) be greater after the combination
of swimming and resistance exercise than either alone.
METHODS Study protocol. The subjects for this
study were seven collegiate female swimmers (age 20.4 ± 0.5 yr, wt
63.8 ± 1.9 kg). The study design, purpose, and possible risks were
carefully explained to each subject before written consent was
obtained. The experimental protocol was approved by the Institutional
Review Board of the University of Texas Medical Branch (UTMB) at
Galveston.
Each subject was studied four times:
1) at rest,
2) after a swimming workout (SW),
3) after a resistance exercise
workout with no swimming on that day (RW), and
4) after swimming and resistance exercise combined (SR). All subjects were studied during the early follicular phase (days 1-8) of
their menstrual cycle with two exceptions. Due to prior commitments,
two subjects were studied 2 days before the beginning of menstrual flow
on one occasion each. Serum estradiol values, measured immediately on
awakening, were at follicular levels (<370 pmol/l) for all subjects
during each of the study days. Because the subjects were all
competitive athletes, it was not possible to control the diets or
workouts before the study days. Each subject was asked not to
participate in a resistance exercise workout on the day before each
study day. Diet records were kept for 3 days before each study day, and
no differences were found between treatments for total energy intake,
percent protein, percent carbohydrates, or percent fat (data not
shown).
The subjects reported to the UTMB General Clinical Research Center
(GCRC) the evening before each study. No food was ingested after 2200. Immediately after the subjects awoke the following morning
(approximately 0700), a 5-ml blood sample was obtained for hormone
analysis. For the three exercise treatments, the subjects were then
taken to the UTMB Field House, and the assigned workouts were
performed. Immediately (~30 min) after each workout, the subjects
returned to the GCRC for a 5-h infusion protocol to measure PS and
protein degradation. The workouts for each of the three experimental
days were randomized, similar to those assigned by their coach, and
normally performed by the swimmers during the swim season. The volumes
and intensities of weight workouts for both RW and SR and of both swim
workouts for SW and SR were standardized for all swimmers.
Workouts. The RW workout included
bench press [three sets of six repetitions at 80% of one
repetition maximum (1 RM, the maximum weight that could be lifted in
one attempt)]; military press, side laterals,
latissimus pulldowns, bicep curls, and tricep pushdowns (3 sets of 10 at 65% of 1 RM); leg press, leg extension, leg curl, hip
adduction, and hip abduction (3 sets of 10 at 65% of 1 RM); and
abdominal crunches (2 sets of 30). There was a 60- to 90-s rest between
each set. The RW workout was completed in ~1 h. Determinations of 1 RM were made at least 1 wk before participation in the study.
The SW workout was a 4,600 m workout of primarily high-intensity
intermittent swimming. The workout consisted of
1) warm-up [500-m freestyle,
200-m kick, 200-m pull, and 200-m technique drills (4 × 50 m at
increasing intensity)]; 2)
main set (10 × 200 m at a pace that resulted in an intensity of
85-90% of maximum age-predicted heart rate);
3) kick set (4 × 100 m);
4) pull sets [2 × 100-m
(4 × 25-m × 2 sets) alternating freestyle and
nonfreestyle]; and 5) 200-m
cooldown. The SW lasted ~1.5 h. The SR treatment was a combination of
the SW workout followed by the RW workout with a 15- to 20-min rest
between the two. SR was completed in ~2.75 h.
Infusion protocol. Immediately (~30
min) after each workout, the swimmers returned to the GCRC for the
infusion protocol. A 20-gauge polyethylene catheter was placed into a
forearm vein for infusion of labeled amino acids. A background blood
sample (3 ml) was obtained, and a primed constant infusion of
ring-[13C6]phenylalanine
(Phe; Cambridge Isotope Laboratories, Woburn MA) was started
(prime = 2.0 µmol/kg, infusion rate = 0.05 µmol · kg Two muscle biopsies were taken from the subject's posterior deltoid
muscle under sterile conditions with a 4-mm Bergström needle.
Approximately 10-40 mg of muscle tissue were sampled with each
biopsy. The first biopsy was taken after 1 h of infusion at isotopic
equilibrium (2). The second biopsy was taken at the end of the infusion
period (~300 min) to measure the incorporation of tracer into muscle
protein. Blood, visible fat, and connective tissue were quickly removed
from the sample, and the tissue was immediately frozen in liquid
nitrogen and stored at Analysis. Phe was partially purified
from plasma samples by cation-exchange chromatography and prepared as
described previously (2, 28). The
t-butyldimethylsilyl derivative of Phe
was prepared for each dried amino acid sample. Isotopic enrichment of
Phe in the derivatized samples was determined by gas
chromatography-mass spectrometry (GC-MS). A Hewlett-Packard (HP) model
5971A fitted with an HP 5890-II gas chromatograph and using a 30-m
fused-silica capillary column (Supelco, Belafonte, PA), electron impact
ionization, and selected-ion monitoring at
m/e
234 and 240 was utilized for GC-MS analysis. Enrichment data are
expressed as the tracer-to-tracee ratio (t/T). The t/T is essentially
equal to the isotopic abundance of the sample minus the isotopic
abundance of the background and is analogous to the specific activity
term used in radioactive tracer studies (27, 28).
Muscle biopsy tissue samples were analyzed for protein-bound Phe
enrichment as described previously (2, 28). Briefly, each sample was
weighed, and the muscle protein was precipitated with 0.5 ml of 10%
trichloroacetic acid. The tissue was then homogenized and centrifuged.
The supernatant was collected, and this procedure was repeated twice
more. The remaining pellet of muscle tissue was washed in
double-distilled H2O
and three times in absolute ethanol and then placed in a 50°C oven
and dried overnight. The dried pellet was placed in 6 N HCl and
hydrolyzed for 24 h at 110°C. The protein hydrolysate was then
passed through columns of acid-washed celite to remove carbon
particles. The purified samples were dried with a speed vacuum. Phe was
isolated from the amino acid mixture and purified by high-performance
liquid chromatography (Pharmacia LKB Biotechnology, Uppsala,
Sweden) as described previously (2). The samples
containing pure Phe were combusted at 700°C in a vacuum with a
carbon-nitrogen analyzer (Nitrogen Analyzer 1500, Carlo Erba, Serono,
Italy). The resulting CO2 gas was
automatically injected into an isotope-ratio mass spectrometer (IRMS;
VG Isogas, VG Instruments, Middlewich, UK) for determination of the
13C-to-12C
isotope ratio
(13C/12C)
in protein-bound Phe. Each sample was checked against a reference gas
(2).
Calculations. The fractional synthetic
rate (FSR) of muscle protein was calculated according to the equation
FSR (in %/h) = [(Et1 Phe was chosen as the tracer because it is not oxidized in muscle or
synthesized in the body. Therefore, the new appearance of Phe results
entirely from protein breakdown (PB). Whole body Phe appearance was
calculated according to the equation
Ra = F (in
µmol · kg Statistical analysis. This study was
designed as a randomized block design, where each "block" is a
subject and the four treatments are RW, SW, SR, and rest. The average
values of FSR and whole body Phe
Ra were compared by one-way
repeated-measures analyses of variance with SigmaStat software (Jandel
Scientific Software, San Rafael, CA). Any significant differences were
then tested with a Student-Newman-Keuls multiple comparison post hoc
test. Statistical significance was set at the
P < 0.05 level. Values are
means ± SE.
RESULTS Isotopic steady state was reached after 1 h of infusion. An enrichment
vs. time curve for each treatment for a representative subject is shown
in Fig. 1.
Figure 2 illustrates the whole body Phe
Ra (in
µmol · min
The FSR in the posterior deltoid at rest and after each of the workouts
is illustrated in Fig. 3. The SR workout
significantly increased the FSR by 81% over resting levels
(P < 0.05). Although the mean FSR
values after SW were 35 and 41% greater than those after RW and at
rest, respectively, there were no significant differences between the
means. FSR after SR was 30% greater than after SW and 73% greater
than after RW, but the differences did not reach statistical
significance.
DISCUSSION The purpose of this study was to examine the acute response of muscle
PS in female swimmers after exercise by measuring the incorporation of
labeled Phe (FSR). Although there was no significant effect of either
swimming alone or resistance exercise alone on FSR, the combination of
swimming and resistance exercise significantly stimulated the FSR above
the resting value. There were no increases over rest in WBPB 3 h after
any of the workouts. Thus it appears that the combination of swimming
and resistance exercise workout provided a greater stimulatory effect
on PS than either swimming or resistance exercise alone.
Before the present study, muscle PS after the combination of endurance
and resistance exercise had not been examined in human subjects.
However, several studies have reported the response of muscle PS to
resistance exercise or endurance exercise alone. Previously, Biolo et
al. (3) found that muscle PS in the vastus lateralis 4 h postexercise
was increased by 133% in untrained men. Chesley et al. (5) reported a
50% increase in the FSR in the biceps immediately after weight lifting
in trained men. Furthermore, Carraro et al. (4) reported a
qualitatively similar significant increase in FSR after the completion
of 4 h of treadmill walking at 40% of the maximal
O2 uptake in six untrained men. In
the present study, FSR was increased by 80% after the combination of
swimming plus resistance exercise.
There are several possible explanations for the lack of a significant
effect of either resistance exercise or swimming on muscle FSR in the
present study. Gender differences in the response of protein metabolism
may have contributed to the apparent discrepancies between the present
results and the previously published papers (3-5). Phillips et al.
(19) showed that the leucine oxidation during endurance exercise was
different in trained men compared with trained women, although there
was no difference in nonoxidative leucine disposal, an indicator of
whole body PS. Yarasheski et al. (29) reported that FSR increased over
rest in each of four young untrained women immediately after a
resistance exercise bout, but no statistics were reported separately on
the female and male subjects. Interpretation is further complicated by
the fact that the resting measurements were made before 2 wk of
resistance training. Ours is the first study to report the acute
response of muscle FSR to exercise specifically in trained women.
Accordingly, there are no data available on the comparison of the
muscle protein synthetic response after either endurance or resistance
exercise in trained men and women.
Alternatively, the lack of an increase in FSR with either resistance or
endurance exercise over resting levels may be due to the muscles
sampled. Previous studies measured incorporation of amino acids in the
vastus lateralis (3, 4) and biceps brachii (5), whereas we studied the
posterior deltoid. It is possible that the response of the FSR to
resistance exercise differs according to muscle fiber type composition.
PS and PB respond differently in fast-twitch and slow-twitch muscles
(11, 26). Even though the deltoid of trained swimmers has been shown to vary between 62 and 75% slow-twitch fibers (7, 12, 16), the vastus
lateralis in untrained men has a relatively even fiber type
distribution (22), and the biceps in trained male weight lifters seems
to be mostly (60%) fast-twitch fibers (1).
In the present study, the FSR was not increased by resistance exercise.
This finding is in contrast to previous studies that found that the FSR
increases on the order of 100% in both trained male weight lifters (5)
and untrained male volunteers (3). The work performed by the selected
muscle in the previous studies may have been greater than that
performed by the posterior deltoid of the swimmers in the present
study. Using the biceps muscles, the trained subjects in the study by
Chesley et al. (5) performed 12 sets of 6-12 repetitions at 80%
of 1 RM. Similarly, Biolo et al. (3) sampled the vastus lateralis of
untrained subjects after the subjects performed 13 sets of 8-10
repetitions at 10-12 RM. The posterior deltoid of the swimmers in
the present study was involved in only 9 sets of 6-10 repetitions
at 65-80% of 1 RM. Although the subjects in the previous studies
participated only in exercises targeting the muscles to be biopsied,
the swimmers in the present study participated in 24 sets of other
exercises in which the deltoid was not involved. The work performed by
the deltoid during SR was greater than that during either RW or SW, and
this may explain why there was a significant increase in FSR after SR.
Postexercise blood flow and amino acid delivery to the muscle have been
positively related to muscle PS (3). It is possible that, compared with
the exercising muscles in the other studies (3, 5), blood flow to the
deltoid was not as high in the present study due to the lower intensity
of the resistance exercise and/or the inclusion of exercises
involving other muscle groups. It is likely that blood flow was
diverted to other exercising muscles and the flow to the deltoid was
reduced. Although blood flow could not be measured in the present
study, the fact that the RW FSR was similar to resting levels is
consistent with a lower level of stress on the deltoid of the swimmers.
Even though a more intense weight-lifting routine might have elicited a
greater response in the FSR, the aim of the study was to determine the response to the workouts that swimmers typically perform.
In the present study, there were no differences in whole body
Ra of Phe 3 h after any of the
exercise routines or at rest. Using a variety of methods, others have
shown increased (3, 10, 21) and unchanged (4, 9, 25) WBPB after
exercise. Although WBPB did not increase due to any of the workouts, as measured with Phe Ra, it is
reasonable to assume that muscle PB did increase. Muscle PB measured
directly (3) and by 3-methylhistidine release (10) has
been reported to increase after exercise, but WBPB may not match muscle
PB (3). The failure of Phe Ra to increase could reflect either a concomitant increase in muscle PB and
decrease in PB from other tissues or simply the insensitivity of the
measurement of whole body Ra.
Previously, Biolo et al. (3) showed that increased muscle
PS after exercise is accompanied by a 50% increase in muscle PB,
whereas WBPB was only slightly increased.
During exercise, the majority of any increase in WBPB that might occur
comes from the splanchnic bed (27). Because there is no evidence that
different types of exercise would cause variable responses in
splanchnic or muscle PB, it is reasonable to assume that muscle PB was
not different among the different workouts in the present study. The
combination of swimming and resistance exercise was the only workout
that resulted in a significant increase in FSR, and there were no
differences in WBPB among any of the workouts. Therefore, the
combination workout provided the greatest increase in net muscle PS. It
is possible that the stimulatory effect of the combination workout on
the FSR was primarily due to the increased work performed during this
exercise bout. It is possible that simply adding additional swimming
would have increased the FSR to the same extent as adding the
resistance exercise to the swimming. However, the purpose of this study
was to investigate the practical implications of adding resistance exercise to swimming workouts in trained swimmers. Given the
limitations of the study, we can conclude that adding a resistance
exercise bout to a swimming workout increases muscle PS in trained
female swimmers.
1 · min1).
Tracer infusion was maintained throughout the experiment by a Harvard
Apparatus 22 infusion pump (South Natick, MA). A wrist vein was
cannulated in a retrograde manner with a 20-gauge polyethylene catheter
and maintained at ~65°C. Three milliliters of arterialized blood
were drawn 60, 240, 260, 280 and 300 min after the infusion began. The
blood was immediately placed into tubes containing 3 ml of 15%
sulfosalicylic acid for precipitation of proteins, shaken vigorously,
and centrifuged. Deproteinized plasma from these samples was stored at
20°C until processing and analysis for Phe enrichment.
70°C for later processing and
analysis.
Et0) · 1.5/(Ep · t)] · 100, where Et0 is
the enrichment
(13C/12C)
in the protein-bound Phe tracer from the first biopsy at
t0 (isotopic
equilibrium at 1 h),
Et1 is the
enrichment (13C/12C)
of the protein-bound Phe tracer from the second biopsy at
t1 (at 5 h),
t is the incorporation time
(t1 t0), and
Ep is the average plasma Phe
enrichment during the time period for determination of protein
incorporation (average from the blood samples taken at isotopic
equilibrium and over the last hour of infusion). The numerator is
multiplied by 1.5 to normalize the IRMS with the enrichment of the
precursor determined by GC-MS. Only six of nine carbons in the Phe
tracer are enriched so a t/T of 0.01 determined by GC-MS would yield a
ratio of 0.0067 if measured by IRMS.
Ep is the t/T skew corrected
(multiplied) by a factor of 0.9376 to account for the different
isotopomer distributions of the tracer and the naturally
occurring Phe (28).
1 · h1)/Ep,
where Ra is the rate of appearance
of Phe and F is the infusion rate of
ring-[13C6]Phe.
Fig. 1.
Phenylalanine enrichment [tracer-to-tracee (t/T) ratio] vs.
time for a representative subject at rest (+) and after a resistance exercise workout (
), swimming workout (
), or combination swimming and resistance exercise workout (
).
[View Larger Version of this Image (36K GIF file)]
1 · kg1)
calculated over the 60-min period from 240-300 min after the beginning of the tracer infusion. Whole body Phe
Ra is representative of WBPB. WBPB
values were similar after each of the workouts and at rest.
Fig. 2.
Whole body phenylalanine (Phe) rate of appearance
(Ra) at rest and after
resistance exercise workout (RW), swimming workout (SW), and combined
swimming and resistance exercise workout (SR) in 7 female swimmers.
Values are means ± SE.
[View Larger Version of this Image (112K GIF file)]
Fig. 3.
Fractional rate of protein synthesis (FSR) of posterior deltoid muscle
at rest and after RW, SW, and SR in 7 female swimmers. Values are means ± SE in %/hr. * Significantly different from rest,
P < 0.05.
[View Larger Version of this Image (21K GIF file)]
ACKNOWLEDGEMENTS
This work was supported in part by the US Olympic Committee, National Institutes of Health General Clinical Research Center Grant M01-RR-000073, National Institute of Diabetes and Digestive and Kidney Diseases Grant DK-38010, and Shriners Hospital Grant 15849.
FOOTNOTES
Address for reprint requests: R. R. Wolfe, Metabolism Unit, Shriners Burns Institute, 815 Market St., Galveston, TX 77550.
Received 12 February 1996; accepted in final form 10 June 1996.
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  M. Beelen, R. Koopman, A. P. Gijsen, H. Vandereyt, A. K. Kies, H. Kuipers, W. H. M. Saris, and L. J. C. van Loon Protein coingestion stimulates muscle protein synthesis during resistance-type exercise Am J Physiol Endocrinol Metab, July 1, 2008; 295(1): E70 - E77. [Abstract] [Full Text] [PDF]
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R. Koopman, M. Beelen, T. Stellingwerff, B. Pennings, W. H. M. Saris, A. K. Kies, H. Kuipers, and L. J. C. van Loon Coingestion of carbohydrate with protein does not further augment postexercise muscle protein synthesis Am J Physiol Endocrinol Metab, September 1, 2007; 293(3): E833 - E842. [Abstract] [Full Text] [PDF]
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C. S. Katsanos, H. Kobayashi, M. Sheffield-Moore, A. Aarsland, and R. R. Wolfe A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly Am J Physiol Endocrinol Metab, August 1, 2006; 291(2): E381 - E387. [Abstract] [Full Text] [PDF]
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 M. A. Pikosky, P. C. Gaine, W. F. Martin, K. C. Grabarz, A. A. Ferrando, R. R. Wolfe, and N. R. Rodriguez Aerobic Exercise Training Increases Skeletal Muscle Protein Turnover in Healthy Adults at Rest J. Nutr., February 1, 2006; 136(2): 379 - 383. [Abstract] [Full Text] [PDF]
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E. Blomstrand, J. Eliasson, H. K. R. Karlsson, and R. Kohnke Branched-Chain Amino Acids Activate Key Enzymes in Protein Synthesis after Physical Exercise J. Nutr., January 1, 2006; 136(1): 269S - 273S. [Abstract] [Full Text] [PDF]
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D. R. Bolster, M. A. Pikosky, P. C. Gaine, W. Martin, R. R. Wolfe, K. D. Tipton, D. Maclean, C. M. Maresh, and N. R. Rodriguez Dietary protein intake impacts human skeletal muscle protein fractional synthetic rates after endurance exercise Am J Physiol Endocrinol Metab, October 1, 2005; 289(4): E678 - E683. [Abstract] [Full Text] [PDF]
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P. C. Gaine, C. T. Viesselman, M. A. Pikosky, W. F. Martin, L. E. Armstrong, L. S. Pescatello, and N. R. Rodriguez Aerobic Exercise Training Decreases Leucine Oxidation at Rest in Healthy Adults J. Nutr., May 1, 2005; 135(5): 1088 - 1092. [Abstract] [Full Text] [PDF]
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M. Sheffield-Moore, D. Paddon-Jones, A. P. Sanford, J. I. Rosenblatt, A. G. Matlock, M. G. Cree, and R. R. Wolfe Mixed muscle and hepatic derived plasma protein metabolism is differentially regulated in older and younger men following resistance exercise Am J Physiol Endocrinol Metab, May 1, 2005; 288(5): E922 - E929. [Abstract] [Full Text] [PDF]
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 B Mittendorfer, J. L Andersen, P Plomgaard, B Saltin, J. A Babraj, K Smith, and M. J Rennie Protein synthesis rates in human muscles: neither anatomical location nor fibre-type composition are major determinants J. Physiol., February 15, 2005; 563(1): 203 - 211. [Abstract] [Full Text] [PDF]
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R. Koopman, D. L. E. Pannemans, A. E. Jeukendrup, A. P. Gijsen, J. M. G. Senden, D. Halliday, W. H. M. Saris, L. J. C. van Loon, and A. J. M. Wagenmakers Combined ingestion of protein and carbohydrate improves protein balance during ultra-endurance exercise Am J Physiol Endocrinol Metab, October 1, 2004; 287(4): E712 - E720. [Abstract] [Full Text] [PDF]
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M. Sheffield-Moore, C. W. Yeckel, E. Volpi, S. E. Wolf, B. Morio, D. L. Chinkes, D. Paddon-Jones, and R. R. Wolfe Postexercise protein metabolism in older and younger men following moderate-intensity aerobic exercise Am J Physiol Endocrinol Metab, September 1, 2004; 287(3): E513 - E522. [Abstract] [Full Text] [PDF]
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 M. P. Engelen, N. E. Deutz, R. Mostert, E. F. Wouters, and A. M. Schols Response of whole-body protein and urea turnover to exercise differs between patients with chronic obstructive pulmonary disease with and without emphysema Am. J. Clinical Nutrition, April 1, 2003; 77(4): 868 - 874. [Abstract] [Full Text] [PDF]
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 A G Williams, M van den Oord, A Sharma, and D A Jones Is glucose/amino acid supplementation after exercise an aid to strength training? Br. J. Sports Med., April 1, 2001; 35(2): 109 - 113. [Abstract] [Full Text] [PDF]
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K. D. Tipton, A. A. Ferrando, S. M. Phillips, D. Doyle Jr., and R. R. Wolfe Postexercise net protein synthesis in human muscle from orally administered amino acids Am J Physiol Endocrinol Metab, April 1, 1999; 276(4): E628 - E634. [Abstract] [Full Text] [PDF]
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 B. D. Roy, M. A. Tarnopolsky, J. D. Macdougall, J. Fowles, and K. E. Yarasheski Effect of glucose supplement timing on protein metabolism after resistance training J Appl Physiol, June 1, 1997; 82(6): 1882 - 1888. [Abstract] [Full Text] [PDF]
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