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Effects of Low-Intensity Cycle Training with Restricted Leg Blood Flow on Thigh Muscle Volume and VO2MAX in Young Men


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Concurrent improvements in aerobic capacity and muscle hypertrophy in response to a single mode of training have not been reported. We examined the effects of low-intensity cycle exercise training with and without blood flow restriction (BFR) on muscle size and maximum oxygen uptake (VO2max). A group of 19 young men (mean age ± SD: 23.0 ± 1.7 years) were allocated randomly into either a BFR-training group (n=9, BFR-training) or a non-BFR control training group (n=10, CON-training), both of which trained 3 days/wk for 8 wk. Training intensity and duration were 40% of VO2max and 15 min for the BFR-training group and 40% of VO2max and 45 min for the CON-training group. MRI-measured thigh and quadriceps muscle cross-sectional area and muscle volume increased by 3.4-5.1% (P < 0.01) and isometric knee extension strength tended to increase by 7.7% (p < 0.10) in the BFR-training group. There was no change in muscle size (~0.6%) and strength (~1.4%) in the CON-training group. Significant improvements in VO2max (6.4%) and exercise time until exhaustion (15.4%) were observed in the BFR-training group (p < 0.05) but not in the CON-training group (-0.1 and 3. 9%, respectively). The results suggest that low-intensity, short-duration cycling exercise combined with BFR improves both muscle hypertrophy and aerobic capacity concurrently in young men. Key pointsConcurrent improvements in aerobic capacity and muscle hypertrophy in response to a single mode of training have not been reported.In the present study, low-intensity (40% of VO2max) cycle training with BFR can elicit concurrent improvement in muscle hypertrophy and aerobic capacity.
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©Journal of Sports Science and Medicine (2010) 9, 452-458
Received: 25 April 2010 / Accepted: 07 June 2010 / Published (online): 01 September 2010
Effects of low-intensity cycle training with restricted leg blood flow on thigh
muscle volume and VO2max in young men
Takashi Abe 1, Satoshi Fujita 1, Toshiaki Nakajima 2, Mikako Sakamaki 1, Hayao Ozaki 1, Riki Oga-
sawara 1, Masato Sugaya 1, Maiko Kudo 3, Miwa Kurano 2, Tomohiro Yasuda 1, Yoshiaki Sato 2, Hiro-
shi Ohshima 4, Chiaki Mukai 4 and Naokata Ishii 3
1 Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan, 2 Graduate School of Medicine, Univer-
sity of Tokyo, Tokyo, Japan, 3 Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan, 4 Japan Aero-
space Exploration Agency, Tsukuba, Japan
Concurrent improvements in aerobic capacity and muscle hyper-
trophy in response to a single mode of training have not been
reported. We examined the effects of low-intensity cycle exer-
cise training with and without blood flow restriction (BFR) on
muscle size and maximum oxygen uptake (VO2max). A group of
19 young men (mean age ± SD: 23.0 ± 1.7 years) were allocated
randomly into either a BFR-training group (n=9, BFR-training)
or a non-BFR control training group (n=10, CON-training), both
of which trained 3 days/wk for 8 wk. Training intensity and
duration were 40% of VO2max and 15 min for the BFR-training
group and 40% of VO2max and 45 min for the CON-training
group. MRI-measured thigh and quadriceps muscle cross-
sectional area and muscle volume increased by 3.4–5.1% (P <
0.01) and isometric knee extension strength tended to increase
by 7.7% (p < 0.10) in the BFR-training group. There was no
change in muscle size (~0.6%) and strength (~1.4%) in the
CON-training group. Significant improvements in VO2max
(6.4%) and exercise time until exhaustion (15.4%) were ob-
served in the BFR-training group (p < 0.05) but not in the CON-
training group (–0.1 and 3.9%, respectively). The results suggest
that low-intensity, short-duration cycling exercise combined
with BFR improves both muscle hypertrophy and aerobic capac-
ity concurrently in young men.
Key words: Muscle hypertrophy, Aerobic exercise, Occlusion,
Muscle strength.
Skeletal muscle shows an enormous plasticity to adapt to
stimuli such as metabolic and/or contractile activities.
Based on the principle of specificity of exercise, resis-
tance exercise elicits specific muscular adaptations, with
little improvement in the physiologic adaptations experi-
enced with typical aerobic training (Hurley et al., 1984).
Conversely, aerobic training is thought to stimulate im-
provements in cardiovascular fitness, such as maximum
oxygen uptake (VO2max) and anaerobic threshold (Wenger
and Bell, 1986). Within muscle, opposite morphologic
and physiologic adaptive responses to the 2 types of train-
ing occur in myofibrillar protein content (Hoppeler, 1986;
Luthi et al., 1986), in mitochondria volume density (Hop-
peler, 1986; MacDougall et al., 1979), in capillary density
(Denis et al., 1986), in enzymes reflecting aerobic energy
production (Gollnick et al., 1973; Tesch et al., 1987), and
in the Akt/mTOR signaling pathway (Coffey and Hawley,
2007). In addition, some studies (Bell et al., 2000;
Kraemer et al., 1995) show interference in strength devel-
opment when aerobic training is added to resistance train-
ing. Thus, it would be advantageous to develop a training
method that can effectively and concurrently improve
both cardiovascular and muscular fitness within a single
mode of training.
Muscular blood flow restriction (BFR) during re-
sistance training has been shown to elicit similar muscle
hypertrophy as traditional high-intensity resistance train-
ing but much lower training intensity (Abe et al., 2005;
Takarada et al., 2002). An intensity as low as that associ-
ated with walking, when combined with BFR, can lead to
significant improvements in muscle strength and leg mus-
cle hypertrophy (Abe et al., 2006; 2010). Recently, our
laboratory demonstrated increased muscle activation
during low-load (20% of 1 repetition maximum [1 RM])
muscle contractions with BFR such that there was a
greater internal activation intensity of the muscle relative
to external load (Yasuda et al., 2008). In addition, signifi-
cantly greater oxygen uptake and heart rate (HR) are
observed during slow treadmill walking with BFR than
during walking without BFR (Abe et al., 2006). The nov-
elty of BFR appears to be the unique combination of
venous blood volume pooling and restricted arterial blood
inflow, which can result in a decreased stroke volume and
increased HR while maintaining cardiac output (Takano
et al., 2005). Consequently, increased HR at the same
systolic blood pressure (SBP) during exercise with BFR
may produce high mechanical stress on the heart, as indi-
cated by a greater rate-pressure product ([HR × SBP]/100)
(Nelson et al., 1974). Furthermore, the increased oxygen
uptake observed during BFR exercise may be the result of
increased arterial and mixed venous blood oxygen (a-v
O2) difference since cardiac output during exercise with
and without BFR is the same. We hypothesized that the
potential benefits of BFR exercise could include not only
an anabolic response by the muscular system (Abe et al.,
2006) but also improvements in cardiovascular fitness.
Thus, the purpose of the current study was to investigate
the effects of low-intensity exercise training combined
with BFR on muscle size and strength, as well as on
VO2max, in young male subjects.
Research article
Abe et al.
Nineteen young men aged 20–26 yr volunteered to par-
ticipate in the study. Subjects were randomized into either
a BFR-training group (n = 9, BFR-training) or a non-BFR
control training group (n = 10, CON-training). The sub-
jects in this study were physically active, but none of the
subjects had participated in regular strength/resistance
and/or aerobic training (less than once a week) for a
minimum of 1 yr prior to the start of the study. Volunteers
who suffered from a chronic disease, such as hyperten-
sion, diabetes, an orthopedic disorder, deep venous
thrombosis, or peripheral vascular disease, were excluded
from the study. All subjects were informed of the meth-
ods, procedures, and risks, and signed an informed con-
sent document before participation. The study was con-
ducted according to the Declaration of Helsinki and was
approved by the institutional review board (IRB) of hu-
man research of Japan Aerospace Exploration Agency
(JAXA) and the Ethics Committee for Human Experi-
ments at the University of Tokyo, Japan.
Training protocol
Training was performed once a day, 3 days/wk, for 8 wk.
Following measurements of body weight and mid-thigh
girth, the subjects performed exercise on an electrically
braked bicycle ergometer (Aerobike 900U, Combi Corpo-
ration, Tokyo, Japan) at a predetermined 40% of VO2max
for 15 min in the BFR training group and at a predeter-
mined 40% of VO2max for 45 min in the CON-training
group. The exercise intensity and duration in each group
remained constant throughout the training period. Sub-
jects in the BFR-training group wore pressure belts
(Kaatsu-Master, Sato Sports Plaza, Tokyo, Japan) on both
legs during cycle exercise training. Prior to BFR training,
the subjects were seated on a chair, the belt air pressure
was set at 120 mmHg (the approximate SBP at heart level
for each subject) for 30 s, and the air pressure was re-
leased. The air pressure was increased by 20 mmHg, held
for 30 s, and then released for 10 s before the next occlu-
sive stimulation was performed. This process was re-
peated until a final occlusion pressure for each training
day was reached. On the first day of training, the final belt
pressure (training pressure) was 160 mmHg. As subjects
adapted to the occlusive stimulus during early phase of
the training, the training pressure was increased by 10
mmHg each week until a final belt pressure of 210 mmHg
was reached. A belt pressure of 160–210 mmHg was
selected for the restriction stimulus based on a review of
the data in young men (Abe et al., 2006). Blood flow to
the leg muscles was restricted for a total of ~18 min (3
min preparation time and 15 min bicycling time) during
each training session, with the belt pressure released im-
mediately upon completion of the session. During all
training sessions, HR was recorded at the 5th min and
15th min for the BFR-training group and CON-training
group, respectively. Ratings of perceived exertion (Borg
15 Point Scale) were also recorded at the end of training
MRI-measured muscle cross-sectional area and vol-
Multislice MRI images of the thigh were obtained using a
General Electric Signa 1.5-T scanner (Milwaukee, WI). A
T1-weighted, spin-echo, axial plane sequence was per-
formed with a 1,500-ms repetition time and a 17-ms echo
time (Figure 1). Subjects rested quietly in the magnet bore
in a supine position with their legs extended. The great
trochanter was used as the origin point, and continuous
Figure 1. Typical MRI images showing transverse sections of the mid-thigh taken before (pre) and after (post) 8 wk
of cycle training with BFR. The images show identical sections midway along the femur in the same subject (KK).
BFR training on muscle and VO2max
transverse images with 1.0-cm slice thickness (0-cm inter-
slice gap) were obtained from the great trochanter to the
lateral condyle of the femur for each subject. All MRI
data were transferred to a personal computer for analysis
using specially designed image analysis software (To-
moVision Inc., Montreal, Canada). For each slice, skeletal
muscle tissue cross-sectional area (CSA) was digitized,
and the muscle tissue volume (cm3) per slice was calcu-
lated by multiplying muscle tissue area (cm2) by slice
thickness (cm). Muscle volume of an individual muscle
was defined as the sum of the slices of muscle. We have
previously determined that the coefficient of variation
(CV) of this measurement was less than 1% (Abe et al.,
2003). This measurement, from the right side of the body,
was completed at baseline and 3 days after the final train-
ing (posttesting).
Maximum isometric strength
Maximum voluntary isometric strength of the knee exten-
sors and flexors was determined using a Biodex System 3
dynamometer (Shirley, NY). Subjects were carefully
familiarized with the testing procedures of voluntary force
production of the thigh muscles during several attempts of
submaximal and maximal muscular contractions ~1 wk
prior to baseline testing. The subjects were seated on a
chair with their hip joint angle positioned at 85˚. The
center of rotation of the knee joint was visually aligned
with the axis of the lever arm of the dynamometer, and
the ankle of the right leg was firmly attached to the lever
arm of the dynamometer with a strap. After a warm-up
consisting of submaximal contractions, the subjects were
instructed to perform maximal isometric (MVC) knee
extension at a knee joint angle of 75˚ and maximal iso-
metric knee flexion at a knee joint angle of 60˚. A knee
joint angle of 0˚ corresponded to full extension of the
knee (Abe et al., 2000). If MVC strength for the first two
trials were varied by >5%, up to an additional MVC was
performed. The coefficient of variation for this test in our
laboratory was 7%. The test was assessed at baseline and
3 days after the final training session (posttesting).
Maximum oxygen uptake
Graded exercise tests on an electrically braked bicycle
ergometer (Aerobike 75XL-II, Combi Corporation, To-
kyo, Japan) were performed in a laboratory where room-
temperature was stabilized at 20–22°C. At the baseline
test, seat height was noted and reproduced for posttraining
testing. The exercise test was started at an initial workload
of 50 W, which was increased by 15 W every minute until
volitional exhaustion. (If the workload reached 200 W, the
rate of increase was 10 W every minute.) During the test,
HR was continuously monitored (HR monitor, Minato
Medical Science Co., Ltd., Osaka, Japan). Ventilation was
also monitored, and oxygen and carbon dioxide concen-
trations in the expired air were continuously measured to
calculate of oxygen uptake (O2), carbon dioxide output
(CO2), and the respiratory gas exchange ratio (RER;
CO2/O2) by a calibrated breath-by-breath system (Aero
monitor AE300S, Minato Medical Science Co., Ltd.,
Osaka, Japan). The following criteria were used to estab-
lish that maximum effort had been achieved: VO2max
appeared as a plateau in VO2 despite an increase in work-
load (increased VO2 within 150 ml min-1), maximum
heart rate within ± 11 beats·min-1 of the age-predicted
maximum (220 minus age), and a maximum respiratory
exchange ratio above 1.15. Exercise time to exhaustion
was also recorded for each subject (Ozaki et al., 2010).
Statistical analyses
StatView, version 4.5, was used to compute the data, and
the results are expressed as means and standard deviations
(SDs) for all variables. Statistical analyses were per-
formed by a 2-way analysis of variance (ANOVA) with
repeated measures (Group [BFR-training and CON-
training] × Time [pre- and posttesting]) to evaluate train-
ing effects for all dependent variables. When appropriate,
post hoc paired t tests were used to assess within-group
changes. All baseline characteristics and percentage
changes in anthropometric variables, skeletal muscle
volume and CSA, muscular strength, and aerobic capacity
were compared between groups with a 1-way ANOVA.
Statistical significance was set at p < 0.05.
At baseline, there were no differences between the two
groups for standing height, body weight, body mass index
(BMI), and mid-thigh girth (Table 1). The subjects in both
training groups completed all training and testing ses-
sions, and no training-related injuries were sustained.
There were no significant changes in body weight and
BMI for either group following the training program;
Table 1. Changes in anthropometric variables and thigh muscle cross-sectional area and muscle volume. Values are mean(SD).
BFR-Training Group CON-Training Group
Pre Post % Pre Post %
Anthropometric variables
Height, m 1.72 (.07) 1.71 (.04)
Weight, kg 61.1 (8.4) 62.0 (9.0) 1.4 61.7 (6.3) 61.4 (6.1) –.4
BMI, kg·m-2 21.2 (2.5) 21.5 (2.5) 1.4 21.0 (2.4) 20.9 (2.3) –.4
Thigh girth, cm 49.7 (3.1) 50.5 (3.0)a 1.7b 50.0 (3.9) 49.7 (3.6) –.6
Muscle cross-sectional area, cm2
Thigh at 50% 142.3 (8.7) 147.1 (9.2)c 3.4d 144.0 (17.6) 144.1 (15.0) .1
Quadriceps at 50% 69.5 (5.4) 72.6 (5.3)c 4.6b 70.7 (7.3) 71.0 (6.5) .6
Muscle volume, cm3
Thigh 3508 (283) 3641 (320)c 3.8b 3696 (447) 3689 (418) –.1
Quadriceps 1575 (153) 1655 (132)c 5.1b 1730 (190) 1731 (180) –.1
BMI, body mass index. Significant differences between BFR-training and CON-training: d p < 0.05, b p < 0.01. Significant differences
between pre- and posttraining: a p < 0.05, c p < 0.01.
Abe et al.
Table 2. Changes in isometric knee extension and flexion strength and specific tension. Values are mean (SD).
BFR-Training Group CON-Training Group
Pre Post % Pre Post %
Isometric muscle strength, Nm
Knee extension 194 (80) 209 (73) 7.7a 216 (47) 219 (45) 1.4
Knee flexion 77 (26) 79 (27) 3.3 87 (23) 84 (16) –3.4
Specific tension, Nm/cm2
Knee extension/qCSA 2.79 (1.08) 2.86 (.90) 2.5 3.05 (0.51) 3.09 (0.54) 1.3
qCSA, quadriceps muscle cross-sectional area (at 50%). Significant differences between BFR-training and CON-training: a p < 0.10.
however, mid-thigh girth increased (p < 0.05) in the BFR-
training group but not in the CON-training group (Table
Muscle CSA increased (p < 0.01) by 3.4% for the
thigh and 4.6% for the quadriceps in the BFR-training
group. Thigh and quadriceps muscle volumes increased (p
< 0.01) by 3.8 and 5.1%, respectively, for the BFR-
training group. Neither muscle CSA nor volume changed
for the CON-training group (Table 1).
Maximal isometric knee extension strength tended
to increase (p < 0.10) in the BFR-training group (7.7%)
but not in the CON-training group (1.4%). There was no
change in isometric knee flexion strength for either group
(Table 2). Relative isometric knee extension strength per
unit quadriceps muscle CSA was similar at pre- and post-
training in both groups.
During training sessions, heart rate (HR) ranged
between 129 and 149 beats/min (50–65% heart rate re-
serve [HRR], mean 59%) for BFR-training subjects and
between 105 and 141beats/min (37–46% HRR, mean
42%) for CON-training subjects. The ratings of perceived
exertion were higher (p < 0.01) in the BFR-training group
than in the CON-training group at the end of training
session (10.5 ± 1.4 and 13.6 ± 1.3, respectively). There
was no change in maximum HR attained during graded
exercise test for either group. Absolute and relative
VO2max increased in the BFR-training group (p < 0.05) but
did not change in the CON-training group. Increase in
exercise time until exhaustion was observed in the BFR-
training group (15.4%, p < 0.01) but not in the CON-
training group (Figure 2).
This study demonstrated that a single mode of low-
intensity (40% of VO2max), short-duration (15 min) exer-
cise training with BFR can elicit improvements in muscle
volume in healthy young subjects. Aerobic capacity also
improved concurrently following the training. Previously,
concurrent improvements in muscular strength and aero-
bic capacity by a single mode of exercise have been
achieved after high-intensity and long-duration exercise
training (Hass et al., 2001; Tabata et al., 1990). However,
none of the studies demonstrated significant muscular
Figure 2. Changes in absolute and relative V
O2max and exercise time. Significant differences between pre- and post-
training: a p < 0.05, b p < 0.01.
HRmax (bpm)
Exercise time (min)
VO2max (l/min)
VO2max (ml/kg/min)
BFR training on muscle and VO2max
hypertrophy, which suggests that the increased strength
was due mainly to neural adaptations. Thus, high-
intensity, long-duration exercise training rarely produces
significant muscle hypertrophy in young and middle-aged
adults. Additionally, it is reported that maximal knee
extension strength was reduced and the thigh muscle
cross-sectional area was unchanged following 4 weeks of
cycle training under conditions of local leg ischaemia,
although VO2max increased with this training (Nygren et
al., 2000; Sundberg, 1994). However, there are few pub-
lished studies documenting concurrent improvements in
VO2max and muscle hypertrophy after aerobic training in
older and failed subjects (Harber et al., 2009; Schwartz et
al., 1991).
Previous studies (Bell et al., 2000; Kraemer et al.,
1995) have shown that combining aerobic training with
resistance exercise negatively affected resistance train-
ing–induced muscular hypertrophy. For instance, Bell et
al. (2000) reported that type I and type II muscle fiber
CSA increased (27% and 28%, respectively) following 12
weeks of high-intensity resistance training (HI-RT), but
the magnitude of increases in fiber CSA in the concurrent
resistance and aerobic training group was less than one-
half of that occurring with resistance training alone (10%
and 14%, respectively). In the present study, the increases
in thigh and quadriceps muscle CSA (4.1% and 5.1%,
respectively) and muscle volume (3.2% and 5.3%, respec-
tively) were similar to the increments observed in previ-
ous HI-RT studies (Jones and Rutherford, 1987; Wilkin-
son et al., 2006), but lower than a short (5-wk) period of
HI-RT studies (Seynnes et al., 2007; Tesch et al., 2004).
Although the differences in mode, intensity, and volume
of exercise might have caused the variability in the train-
ing-induced muscle hypertrophy, it is clear that the mag-
nitude of hypertrophic potential associated with BFR
cycle training is comparable with that associated with HI-
Our previous study (Abe et al., 2006) demon-
strated that slow walk training combined with BFR not
only produced thigh muscle hypertrophy but also in-
creased isometric and dynamic strength of the knee exten-
sor. McCarthy et al. (1995) reported that cycle exercise
training alone did not significantly change isokinetic or
isometric strength, a finding that is consistent with our
CON-training group results. On the other hand, an aver-
age 7.7% change in knee extension strength was observed
when cycle training was combined with BFR. However,
there were large individual variations in strength adapta-
tion in response to cycle training with BFR, which re-
sulted in a nonsignificant increase in isometric knee ex-
tension strength. The specific tension of the knee extensor
muscle did not change significantly between pre- and
posttraining using BFR resistance training (Takarada et
al., 2002) and BFR walk training (Abe et al., 2006); nor
did it change in the present study. Therefore, a main con-
tributor of increased muscle strength after BFR training is
the increase in muscle CSA, which surpasses the neural
adaptation, such as fiber recruitment patterns.
Our results showed that BFR cycle training pro-
duced a 6.4% increase (p < 0.05) in absolute VO2max and a
15.4% increase (p < 0.01) in exercise time until exhaus-
tion. The magnitude of change in VO2max (percentage
increase in VO2max divided by total training sessions) in
the BFR-training group (0.25%) is similar to that reported
in some studies (0.25%–0.26%) (Gaesser and Rich, 1984;
Wilmore et al., 1980), but lower than that reported in
another study (0.60%) (McCarthy et al., 1995). Studies
(Gaesser and Rich, 1984; Wenger and Bell, 1986) have
demonstrated that the magnitude of change in VO2max
increases as exercise intensity increases from 50% to
100% of VO2max. The minimum stimulus necessary to
evoke change is ~50% of VO2max, although 1 study
(Gaesser and Rich, 1984) reported the increase in VO2max
after cycle training to be 45% of VO2max. If exercise in-
tensity is low, longer-duration efforts (>35 min) can be
more effective than shorter-duration efforts at higher
intensity (Wenger and Bell, 1986). During low-intensity
exercise with BFR, stroke volume (SV) decreased and HR
increased without changes in cardiac output (Ozaki et al.,
2010; Takano et al., 2005). In the present study, exercise
intensity and duration were set at 40% of VO2max and 15
min in the BFR-training group. During the training ses-
sions, however, the exercise intensity estimated from
maximum HRR was 59% on average, which is within the
effective exercise intensity for improvements in VO2max.
The exercise training–induced increase in VO2max
is known to be due to central cardiovascular and/or pe-
ripheral metabolic adaptations, and the VO2max is the
product of cardiac output and arterial and mixed venous
blood oxygen (a-v O2) difference at maximal exercise
workload. However, there is a lack of studies investigat-
ing the cardiovascular hemodynamic and muscle meta-
bolic responses to BFR exercise training (Ozaki et al.,
2010). Although the BFR method is different, Sundberg
(1994) found an increase in VO2max by utilizing supine
one-legged cycle training with 50 mmHg chamber pres-
sure (reduced leg blood flow by 16%) for 4 weeks (4
sessions/wk). In that study, muscle enzyme of oxidative
metabolism and capillary density are increased in the
ischaemically-trained leg, but cardiovascular adaptations
to the ischaemic exercise training were not reported. Re-
cently, a study reported that increases in VO2max and sub-
maximal exercise SV were observed after 2 weeks of
twice–daily, 6 days/wk BFR walk training, while resting
SV remain unchanged (Park et al., 2010). Therefore, the
increase in VO2max by BFR training may be due to adapta-
tions in muscle oxidative capacity (a-v O2 difference) and
SV. In addition, increase in lower body muscle mass may
be associated with improvements in VO2max in the BFR
training group.
Few studies have attempted to elucidate the cellu-
lar and molecular mechanisms of adaptation in skeletal
muscle as well as the cardiorespiratory system in response
to low-intensity BFR exercise (Manini and Clark, 2009).
Our previous studies demonstrated that a single bout of
20% of 1-RM intensity knee extension exercise with BFR
increased both vastus lateralis muscle protein synthesis
and the Akt/mTOR signaling pathway in young (Fujita et
al., 2007) and old (Fry et al., 2010) men, although the rate
of muscle protein breakdown was not measured. These
anabolic responses may contribute significantly to BFR
training–induced muscle hypertrophy. However, there
Abe et al.
have not been any studies assessing the changes in mito-
chondrial and capillary density and muscle enzymes re-
flecting aerobic energy production, as well as cardiac
function in response to BFR exercise training. Further
research is needed to clarify the mechanisms of the BFR
training–induced concurrent improvement in both types of
physical fitness.
In conclusion, low-intensity (40% VO2max) cycle training
of short duration (15 min) combined with blood flow
restriction can produce a significant increase in thigh
muscle volume and aerobic capacity in young men.
The authors thank the students who participated in this study. We also
greatly appreciate the assistance of the JAXA staffs. This study is finan-
cially supported in part by JAXA.
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Key points
Concurrent improvements in aerobic capacity and
muscle hypertrophy in response to a single mode of
training have not been reported.
In the present study, low-intensity (40% of VO2max)
cycle training with BFR can elicit concurrent im-
provement in muscle hypertrophy and aerobic ca-
Takashi ABE
Professor, University of Tokyo, Graduate School of Frontier
Sciences, Japan
Research interest
Exercise physiology and sports performance, training science
Satoshi FUJITA
University of Tokyo, Graduate School of Frontier Sciences,
University of Tokyo, Graduate School of Midicine, Japan
University of Tokyo, Graduate School of Frontier Sciences,
University of Tokyo, Graduate School of Frontier Sciences,
Research interest
Exercise physiology, sport and training science
University of Tokyo, Graduate School of Frontier Sciences,
University of Tokyo, Graduate School of Frontier Sciences,
Maiko KUDO
University of Tokyo, Graduate School of Arts and Sciences,
University of Tokyo, Graduate School of Medicine, Japan
Tomohiro YASUDA
University of Tokyo, Graduate School of Frontier Sciences,
Research interest
Exercise physiology, sport science
Japan Aerospace Exploration Agency, Japan
Chiaki MUKAI
Japan Aerospace Exploration Agency, Japan
Naokata ISHII
Professor, University of Tokyo, Graduate School of Arts and
Sciences, Japan
Takashi Abe, PhD
Graduate School of Frontier Sciences, University of Tokyo, 5-1-
5 Kashiwanoha, Kashiwa, Chiba, Japan 227-8563
... A previous study reported that low-intensity (40% of VO 2 max) KAATSU aerobic exercise improved muscle strength and mass and also aerobic capacity in healthy adults [12,13]. Therefore, there is a potential that low-intensity KAATSU aerobic exercise can be effective for deconditioned cardiac patients undergoing cardiac rehabilitation. ...
... Generally, low intensity exercise has little or no effect on muscle strength and mass [3]. Nevertheless, previous studies reported that low-intensity (40% of VO 2 max) KAATSU aerobic exercise increased muscle strength and mass [12,13]. Thus, there is a possibility that cellular swelling and/or hypoxia induced by KAATSU-related increase of metabolic stress [8] underlie the increases in muscle strength and mass after low-intensity aerobic exercise. ...
... Thus, there is a possibility that cellular swelling and/or hypoxia induced by KAATSU-related increase of metabolic stress [8] underlie the increases in muscle strength and mass after low-intensity aerobic exercise. In this study, VO 2 at VT in KAATSU was 46.6% of VO 2 max (i.e., relative to VO 2 at peak power output in no-KAATSU), not lower than the exercise intensity of 40% of VO 2 max used in previous studies [12,13]. These suggest that aerobic exercise training with KAATSU at VT for several weeks may have a potential to increase aerobic capacity and muscle strength and mass. ...
Full-text available
Low-intensity endurance exercise with blood flow restriction (KAATSU) is under consideration for use in cardiac rehabilitation. However, the physiological responses to such exercise have not yet been fully characterized. In an initial effort in healthy males (n = 11, age: 26.3±4.6 y), we compared the physiological responses to low-intensity endurance exercise with and without a thigh KAATSU. Participants performed maximal graded exercise testing using a cycle ergometer with or without KAATSU. We examined responses to cycling exercise at ventilatory threshold (VT) in heart rate (HR), oxygen consumption (VO 2 ), dyspnea, ratings of perceived exertion (RPE), blood pressure (BP), and rectus femoris activation. Participants reached VT at a lower mechanical load, HR, VO 2 , dyspnea, and double product (HR×systolic BP) with KAATSU vs. no-KAATSU. At VT, RPE, and rectus femoris activity did not differ between the two conditions. These results suggest that KAATSU reduced exercise intensity to reach VT and the physiological responses to exercise at VT without changes in knee extensor muscle activation. Results from this pilot study in healthy males suggest that KAATSU aerobic exercise at VT intensity has the potential to be an effective and low-burden adjuvant to cycling in cardiac rehabilitation.
... Both continuous and interval-style endurance training combined with blood flow restriction (BFR) have been shown to result in large (~5%-10%) improvements in maximal aerobic capacity (VO 2 max). [1][2][3][4][5][6][7] While it is common for the untrained to demonstrate significant adaptations to a novel training stimulus, similar improvements have been reported amongst highly trained (VO 2 max ≥ 60 mL . kg -1. ...
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Aim Assess the effect of low‐ and high‐volume blood flow restriction training (BFR) on maximal aerobic capacity (VO2max) and determine if alteration in VO2max is mediated through changes in hemoglobin mass (Hbmass) and blood volume. Methods Participants' Hbmass (CO‐rebreathe), single, and double‐leg VO2max and blood volume regulating hormonal responses (renin and copeptin) were measured before and after BFR training. Training consisted of treadmill walking either (1) twice‐daily for 4week (CON and BFRHV) or (2) twice‐weekly for 6week (BFRLV). Each session consisted of five intervals (3 min, 5% incline, 5 km/h, 100% of lowest occlusion pressure), with 1 min of standing rest between sets. Results VO2max increased using both training exposures, in as quickly as 2‐weeks (BFRLV baseline to 4week: +315 ± 241 mL (8.7%), p = 0.02; BFRHV baseline to 2week: +360 ± 261 mL (7.9%), p < 0.01), for the BFRLV and BFRHV groups, with no change in CON. Single‐ and double‐leg VO2max improved proportionately (single/double‐leg VO2max ratio: BFRLV 78 ± 4.9–78 ± 5.8%, BFRHV 79 ± 6.5–77 ± 6.5%), suggesting that the mechanism for increased VO2max is not solely limited to central or peripheral adaptations. Hbmass remained unchanged across groups (CON: +10.2 ± 34 g, BFRLV: +6.6 ± 42 g, BFRHV: +3.2 ± 44 g; p = 0.9), despite a significant release of blood volume regulating hormones after initial BFR exposure (renin +20.8 ± 21.9 ng/L, p < 0.01; copeptin +22.0 ± 23.8 pmol/L, p < 0.01), which was blunted following BFRHV training (renin: +13.4 ± 12.4 ng/L, p = 0.09; copeptin: +1.9 ± 1.7 pmol/L, p = 0.98). Conclusion BFR treadmill walking increases VO2max irrespective of changes in Hbmass or blood volume despite a large release of blood volume regulating hormones in response to BFR treadmill walking.
... In studies on muscle hypertrophy induced by BFR training, different application methods of external pressure resulted in different degrees of fatigue. Moore and Pierce used arbitrary, subjective pressure values to implement a BFR training program 14,15 , while Abe and Yasuda calculated external blood limit pressure based on brachial artery resting systolic pressure and applied it in their experimental design 16,17 . Loenneke et al. pointed out that neither of the above two methods represents an effective strategy for personalizing the pressures of the lower limbs 18 . ...
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We aimed to investigate acute changes before and after low-intensity continuous and intermittent blood flow restriction (BFR) deep-squat training on thigh muscle activation characteristics and fatigue level under suitable individual arterial occlusion pressure (AOP). Twelve elite male handball players were recruited. Continuous (Program 1) and intermittent (Program 2) BFR deep-squat training was performed with 30% one-repetition maximum load. Program 1 did not include decompression during the intervals, while Program 2 contained decompression during each interval. Electromyography (EMG) was performed before and after two BFR training programs in each period. EMG signals of the quadriceps femoris, posterior femoral muscles, and gluteus maximus, including the root mean square (RMS) and normalized RMS and median frequency (MF) values of each muscle group under maximum voluntary contraction (MVC), before and after training were calculated. The RMS value under MVC (RMSMVC) of the rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), and gluteus maximus (GM) decreased after continuous and intermittent BFR training programs, and those of the biceps femoris (BF) and semitendinosus (SEM) increased; The RMS standard values of the VL, BF, and SEM were significantly increased after continuous and intermittent BFR training (P < 0.05), The RMS value of GM significantly decreased after cuff inflating (P < 0.05). The MF values of RF, VM, VL, and GM decreased significantly after continuous BFR training (P < 0.05). Continuous BFR deep-squat training applied at 50% AOP was more effective than the intermittent BFR training program. Continuous application of BFR induces greater levels of acute fatigue than intermittent BFR that may translate into greater muscular training adaptations over time.
... Low-intensity aerobic training programs with blood flow restriction (BFR) produces significant increases in strength, muscle mass, and cardiorespiratory capacity [1,2]. Furthermore, low-load resistance training (LL-RT) programs (20-40% of 1 repetition maximum) with BFR can elicit similar muscle hypertrophy as high-load resistance training [3] and the application of passive BFR (i.e., without exercise) appears to minimize disuse atrophy [4]. ...
Full-text available
Purpose It is recommended that the pressure applied in training with blood flow restriction (BFR) be relativized based on the arterial occlusion pressure (AOP). However, several factors can affect the measurement of AOP that may require consideration. The purpose of this review was to explore variables capable of impacting AOP and provide recommendations for measurement. Methods On August 8, 2023, PubMed ® and Scopus databases were consulted to identify studies that analyzed variables capable of affecting AOP. In addition, the list of references of eligible studies, as well as Google Scholar citations, were consulted to identify additional studies. Results Twenty-three studies (n = 1335 participants) were included in this review. Studies analyzed the effects of cuff characteristics (n = 9), cuff bladder position (n = 1), body position (n = 6), inflation protocol (n = 1), time (n = 1), sex (n = 5), and segment (n = 5) on AOP. Results demonstrated that wider cuffs promote arterial occlusion with lower external pressures. In addition to width, cuff placement also affects AOP; when the bladder is positioned above the artery, less external pressure is needed to promote arterial occlusion. Body position significantly affects AOP, with more pronounced effects in the lower limbs. The time of day AOP is measured, but not the inflation protocol, has a significant effect on AOP. For the effect of sex and segment, results were divergent. Conclusion In conclusion, several factors may influence AOP. For standardizing the prescribed pressure in training with BFR, all these variables should be considered.
... However, it remains unknown whether the same training volume of LIT + BFR would yield similar effects. Most studies investigating blood flow restriction (BFR) interventions have primarily focused on designs maximizing their effectiveness for increasing muscle strength and hypertrophy (22,23). However, during the recovery period following an injury, the primary objective of training is to maintain strength and endurance levels using minimal load and training volume (20). ...
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Introduction: It is acknowledged that training during recovery periods after injury involves reducing both volume and intensity, often resulting in losses of sportspecific fitness. Therefore, this study aimed to compare the effects of highintensity training (HIT) and low-intensity training with blood flow restriction (LIT + BFR) of the finger flexors in order to preserve climbing-specific strength and endurance. Methods: In a crossover design, thirteen intermediate climbers completed two 5- week periods of isometric finger flexors training on a hangboard. The trainings consisted of ten LIT + BFR (30% of max) or HIT sessions (60% of max without BFR) and were undertaken in a randomized order. The training session consisted of 6 unilateral sets of 1 min intermittent hanging at a 7:3 work relief ratio for both hands. Maximal voluntary contraction (MVC), force impulse from the 4 min all out test (W), critical force (CF) and force impulse above the critical force (W’) of the finger flexors were assessed before, after the first, and after the second training period, using a climbing-specific dynamometer. Forearm muscle oxidative capacity was estimated from an occlusion test using near-infrared spectroscopy at the same time points. Results: Both training methods led to maintaining strength and endurance indicators, however, no interaction (P > 0.05) was found between the training methods for any strength or endurance variable. A significant increase (P = 0.002) was found for W, primarily driven by the HIT group (pretest—25078 ± 7584 N.s, post-test—27327 ± 8051 N.s, P = 0.012, Cohen’s d = 0.29). There were no significant (P > 0.05) pre- post-test changes for MVC (HIT: Cohen’s d = 0.13; LIT + BFR: Cohen’s d = −0.10), CF (HIT: Cohen’s d = 0.36; LIT + BFR = 0.05), W` (HIT: Cohen’s d = −0.03, LIT + BFR = 0.12), and forearm muscle oxidative capacity (HIT: Cohen’s d = −0.23; LIT + BFR: Cohen’s d = −0.07). Conclusions: Low volume of BFR and HIT led to similar results, maintaining climbing-specific strength and endurance in lower grade and intermediate climbers. It appears that using BFR training may be an alternative approach after finger injury as low mechanical impact occurs during training.
... The technique consists of performing exercise (e. g., walking or resistance training) with an ar-terial BFR generated with inflatable cuffs (or elastic bands) fixed to the proximal region of the exercised limb [2]. Low-intensity aerobic training with BFR can increase strength, muscle hypertrophy, and cardiopulmonary function -adaptations that typically do not occur following low-intensity training without BFR [3,4]. Therefore, this training modality can be an alternative for people who have limitations to practicing regular high-intensity training [5]. ...
... This generates a local hypoxic environment and inhibits metabolite clearance (Manini and Clark 2009). When used chronically, BFO is suggested to increase mitochondrial biogenesis (Keramidas et al. 2012), capillarization, and cardiac output (Mitchell et al. 2019), which collectively might contribute to a larger gain in aerobic capacity (Abe et al. 2010;de Oliveira et al. 2016). However, from an acute perspective, accumulation of metabolites (e.g., Communicated by Guido Ferretti. ...
Full-text available
Purpose Constant blood flow occlusion (BFO) superimposed on aerobic exercise can impair muscle function and exercise tolerance; however, no study has investigated the effect of intermittent BFO on the associated responses. Fourteen participants (n = 7 females) were recruited to compare neuromuscular, perceptual, and cardiorespiratory responses to shorter (5:15s, occlusion-to-release) and longer (10:30s) BFO applied during cycling to task failure. Methods In randomized order, participants cycled to task failure (task failure 1) at 70% of peak power output with (i) shorter BFO, (ii) longer BFO, and (iii) no BFO (Control). Upon task failure in the BFO conditions, BFO was removed, and participants continued cycling until a second task failure (task failure 2). Maximum voluntary isometric knee contractions (MVC) and femoral nerve stimuli were performed along with perceptual measures at baseline, task failure 1, and task failure 2. Cardiorespiratory measures were recorded continuously across the exercises. Results Task failure 1 was longer in Control than 5:15s and 10:30s (P < 0.001), with no differences between the BFO conditions. At task failure 1, 10:30s elicited a greater decline in twitch force compared to 5:15s and Control (P < 0.001). At task failure 2, twitch force remained lower in 10:30s than Control (P = 0.002). Low-frequency fatigue developed to a greater extent in 10:30s compared to Control and 5:15s (P < 0.047). Dyspnea and Fatigue were greater for Control than 5:15s and 10:30s at the end of task failure 1 (P < 0.002). Conclusion Exercise tolerance during BFO is primarily dictated by the decline in muscle contractility and accelerated development of effort and pain.
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Objective: This study aimed to investigate the effect of whole-body vibration training (WBVT) combined with KAATSU training (KT) on lower limb joint muscle strength and to provide a reference for improving muscle strength in older women. Methods: A total of 86 healthy older people was randomly divided into WBVT group (WG, n = 21), KT group (KG, n = 22), combined intervention group (CIG, n = 20) and control group (CG, n = 23). WG and CIG subjects underwent WBVT, and KG and CIG subjects underwent 150 mmHg and lower limb joint and local compression intervention for 16 weeks (three times per week, about 15 min/time). The peak torque (PT) and endurance ratio (ER) of joint flexion or extension were tested for all subjects. Results: 1) Results at 16 weeks were compared with the baseline data. The knee extension and ankle flexion PT (60°/s) in CIG increased by 14.3% and 15.3%, respectively ( p < 0.05). The knee extension PT (180°/s) increased by 16.9, 18.4% and 33.3% in WG, KG and CIG ( p < 0.05), respectively, and the ankle extension PT (180°/s) in CIG increased by 31.1% ( p < 0.05). The hip, knee extension and ankle flexion ER increased by 10.0, 10.9% and 5.7% in CIG ( p < 0.05), respectively. 2) Results were compared among groups at 16 weeks. The relative changes were significantly lower in WG, KG and CG compared to CIG in the knee extension and ankle flexion PT (60°/s) ( p < 0.05). The relative changes were significantly greater in WG, KG and CIG compared to CG in the knee extension PT (180°/s) ( p < 0.05). The relative changes were significantly lower in WG, KG and CG compared to CIG in the ankle extension PT (180°/s) ( p < 0.05). The relative changes were significantly lower in WG, KG and CG compared to CIG in the hip extension ER ( p < 0.05). The relative changes were significantly lower in CG compared to CIG in the knee extension ER ( p < 0.05). Conclusion: Sixteen-week WBVT and KT increased the knee extensor strength in older women. Compared with a single intervention, the combined intervention had better improvements in the knee extensor and ankle flexor and extensor strength and hip extension muscle endurance. Appears to be some additional benefit from combined intervention above those derived from single-interventions.
Für eine optimale Steuerung von Trainingsumfängen und -intensitäten im Leistungssport oder in der Rehabilitation nach Verletzungen und Erkrankungen werden zunehmend neuartige Trainingsmethoden integriert. Das Blutflussrestriktionstraining (engl. Blood-Flow-Restriction Training, BFR) beschreibt eine dieser neuen Trainingsmethoden, bei der es zu einer Anwendung von speziellen Blutdruckmanschetten während der Belastung an den Extremitäten kommt. Das vorliegende Positionspapier zielt darauf ab, eine umfassende Beschreibung der BFR-Trainingsmethode, deren bisher dargestellten Wirkmechanismen und möglichen unerwünschten Wirkungen zu geben.
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The purpose was to investigate muscle activation during low- intensity muscle contractions with various levels of external limb compression to reduce muscle perfusion/outflow. A series of unilateral elbow flexion muscle contractions (30 repetitive contractions followed by 3 sets x 15 contractions) was performed at 20% of 1RM with varying levels of external compression (0 (without compression), 98, 121, and 147 mmHg external compression) around the upper arm. Electromyography (EMG) signals were recorded from surface electrodes placed on the biceps brachii muscle and analyzed for integrated EMG (iEMG). Maximal voluntary isometric contraction (MVC) decreased similarly during the control (0 mmHg) and 98 mmHg external compression bout (~18%); the decline in MVC with 121 and 147 mmHg external compression was significantly greater (~37%). Muscle activation increased progressively throughout the contraction bout with each level of external compression, but iEMG was significantly greater during 147 mmHg external compression. In conclusion, low-intensity muscle contractions performed with external compression of 147 mmHg appears to alter muscle perfusion/outflow leading to increased muscle activation without decrements in work performed during the contraction bout. Key pointsLow-intensity muscle contractions with external compression are maintained by greater neural activation.It appears there is optimal external compression pressure for increased muscle activation without exaggerated fatigue.External compression per arm circumference was related to the neuromuscular response and fatigue.
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The purpose of this study was to examine the metabolic and cardiovascular response to exercise without (CON) or with (BFR) restricted blood flow to the muscles. Ten young men performed upright cycle exercise at 20, 40, and 60% of maximal oxygen uptake, VO2max in both conditions while metabolic and cardiovascular parameters were determined. Pre-exercise VO2 was not different between CON and BFR. Cardiac output (Q) was similar between the two conditions as a 25% reduction in stroke volume (SV) observed in BFR was associated with a 23% higher heart rate (HR) in BFR compared to CON. As a result rate-pressure product (RPP) was higher in the BFR but there was no difference in mean arterial pressure (MAP) or total peripheral resistance (TPR). During exercise, VO2 tended to increase with BFR (~10%) at each workload. Q increased in proportion to exercise intensity and there were no differences between conditions. The increase in SV with exercise was impaired during BFR; being ~20% lower in BFR at each workload. Both HR and RPP were significantly greater at each workload with BFR. MAP and TPR were greater with BFR at 40 and 60% VO2max. In conclusion, the BFR employed impairs exercise SV but central cardiovascular function is maintained by an increased HR. BFR appears to result in a greater energy demand during continuous exercise between 20 and 60% of control VO2max; probably indicated by a higher energy supply and RPP. When incorporating BFR, HR and RPP may not be valid or reliable indicators of exercise intensity. Key pointsBlood flow reduction (BFR) employed impairs stroke volume (SV) during exercise, but central cardiovascular function is maintained by an increased heart rate (HR).BFR appears to result in a greater energy demand during continuous exercise between 20 and 60% of control VO2max;Probably indicated by a higher energy supply (VO2) and rate-pressure product (HR x systolic blood pressure).
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Thirty-five healthy men were matched and randomly assigned to one of four training groups that performed high-intensity strength and endurance training (C; n = 9), upper body only high-intensity strength and endurance training (UC; n = 9), high-intensity endurance training (E; n = 8), or high-intensity strength training (ST; n = 9). The C and ST groups significantly increased one-repetition maximum strength for all exercises (P < 0.05). Only the C, UC, and E groups demonstrated significant increases in treadmill maximal oxygen consumption. The ST group showed significant increases in power output. Hormonal responses to treadmill exercise demonstrated a differential response to the different training programs, indicating that the underlying physiological milieu differed with the training program. Significant changes in muscle fiber areas were as follows: types I, IIa, and IIc increased in the ST group; types I and IIc decreased in the E group; type IIa increased in the C group; and there were no changes in the UC group. Significant shifts in percentage from type IIb to type IIa were observed in all training groups, with the greatest shift in the groups in which resistance trained the thigh musculature. This investigation indicates that the combination of strength and endurance training results in an attenuation of the performance improvements and physiological adaptations typical of single-mode training.
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This study investigated the effects of twice daily sessions of low-intensity resistance training (LIT, 20% of 1-RM) with restriction of muscular venous blood flow (namely "LIT-Kaatsu" training) for two weeks on skeletal muscle size and circulating insulin-like growth factor-1 (IGF-1). Nine young men performed LIT-Kaatsu and seven men performed LIT alone. Training was conducted two times / day, six days / week for 2 weeks using 3 sets of two dynamic exercises (squat and leg curl). Muscle cross-sectional area (CSA) and volume were measured by magnetic resonance imaging at baseline and 3 days after the last training session (post-testing). Mid-thigh muscle-bone CSA was calculated from thigh girth and adipose tissue thickness, which were measured every morning prior to the training session. Serum IGF-1 concentration was measured at baseline, mid-point of the training and post-testing. Increases in squat (17%) and leg curl (23%) one-RM strength in the LIT-Kaatsu were higher (p<0.05) than those of the LIT (9% and 2%). There was a gradual increase in circulating IGF-1 and muscle-bone CSA (both p<0.01) in the LIT-Kaatsu, but not in the LIT. Increases in quadriceps, biceps femoris and gluteus maximus muscle volume were, respectively, 7.7%, 10.1% and 9.1% for LIT-Kaatsu (p<0.01) and 1.4%, 1.9% and -0.6% for LIT (p>0.05). There was no difference (p>0.05) in relative strength (1-RM / muscle CSA) between baseline and post-testing in both groups. We concluded that skeletal muscle hypertrophy and strength gain occurred after two weeks of twice daily LIT-Kaatsu training.
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The loss of skeletal muscle mass during aging, sarcopenia, increases the risk for falls and dependence. Resistance exercise (RE) is an effective rehabilitation technique that can improve muscle mass and strength; however, older individuals are resistant to the stimulation of muscle protein synthesis (MPS) with traditional high-intensity RE. Recently, a novel rehabilitation exercise method, low-intensity RE, combined with blood flow restriction (BFR), has been shown to stimulate mammalian target of rapamycin complex 1 (mTORC1) signaling and MPS in young men. We hypothesized that low-intensity RE with BFR would be able to activate mTORC1 signaling and stimulate MPS in older men. We measured MPS and mTORC1-associated signaling proteins in seven older men (age 70+/-2 yr) before and after exercise. Subjects were studied identically on two occasions: during BFR exercise [bilateral leg extension exercise at 20% of 1-repetition maximum (1-RM) with pressure cuff placed proximally on both thighs and inflated at 200 mmHg] and during exercise without the pressure cuff (Ctrl). MPS and phosphorylation of signaling proteins were determined on successive muscle biopsies by stable isotopic techniques and immunoblotting, respectively. MPS increased 56% from baseline after BFR exercise (P<0.05), while no change was observed in the Ctrl group (P>0.05). Downstream of mTORC1, ribosomal S6 kinase 1 (S6K1) phosphorylation and ribosomal protein S6 (rpS6) phosphorylation increased only in the BFR group after exercise (P<0.05). We conclude that low-intensity RE in combination with BFR enhances mTORC1 signaling and MPS in older men. BFR exercise is a novel intervention that may enhance muscle rehabilitation to counteract sarcopenia.
1. Increases in strength and size of the quadriceps muscle have been compared during 12 weeks of either isometric or dynamic strength training. 2. Isometric training of one leg resulted in a significant increase in force (35 +/- 19%, mean +/- S.D., n = 6) with no change in the contralateral untrained control leg. 3. Quadriceps cross-sectional area was measured from mid-thigh X-ray computerized tomography (c.t.) scans before and after training. The increase in area (5 +/- 4.6%, mean +/- S.D., n = 6) was smaller than, and not correlated with, the increase in strength. 4. The possibility that the stimulus for gain in strength is the high force developed in the muscle was examined by comparing two training regimes, one where the muscle shortened (concentric) and the other where the muscle was stretched (eccentric) during the training exercise. Forces generated during eccentric training were 45% higher than during concentric training. 5. Similar changes in strength and muscle cross-sectional area were found after the two forms of exercise. Eccentric exercise increased isometric force by 11 +/- 3.6% (mean +/- S.D., n = 6), and concentric training by 15 +/- 8.0% (mean +/- S.D., n = 6). In both cases there was an approximate 5% increase in cross-sectional area. 6. It is concluded that as a result of strength training the main change in the first 12 weeks is an increase in the force generated per unit cross-sectional area of muscle. The stimulus for this is unknown but comparison of the effects of eccentric and concentric training suggest it is unlikely to be solely mechanical stress or metabolic fluxes in the muscle.
Impairment in strength development has been demonstrated with combined strength and endurance training as compared with strength training alone. The purpose of this study was to examine the effects of combining conventional 3 d[middle dot]wk-1 strength and endurance training on the compatibility of improving both [latin capital V with dot above]O2peak and strength performance simultaneously. Sedentary adult males, randomly assigned to one of three groups (N = 10 each), completed 10 wk of training. A strength-only (S) group performed eight weight-training exercises (4 sets/exercise, 5-7 repetitions/set), an endurance-only (E) group performed continuous cycle exercise (50 min at 70% heart rate reserve), and a combined (C) group performed the same S and E exercise in a single session. S and C groups demonstrated similar increases (P < 0.0167) in 1RM squat (23% and 22%) and bench press (18% for both groups), in maximal isometric knee extension torque (12% and 7%), in maximal vertical jump (6% and 9%), and in fat-free mass (3% and 5%). E training did not induce changes in any of these variables. [latin capital V with dot above]O2peak (ml[middle dot]kg-1min-1) increased (P < 0.01) similarity in both E (18%) and C (16%) groups. Results indicate 3 d[middle dot]wk-1 combined training can induce substantial concurrent and compatible increases in [latin capital V with dot above]O2peak and strength performance. (C)1995The American College of Sports Medicine
Walk training with blood flow occlusion (OCC-walk) leads to muscle hypertrophy; however, cardiorespiratory endurance in response to OCC-walk is unknown. Ischemia enhances the adaptation to endurance training such as increased maximal oxygen uptake (VO₂(max)) and muscle glycogen content. Thus, we investigated the effects of an OCC-walk on cardiorespiratory endurance, anaerobic power, and muscle strength in elite athletes. College basketball players participated in walk training with (n = 7) and without (n = 5) blood flow occlusion. Five sets of a 3-min walk (4-6 km/h at 5% grade) and a 1-min rest between the walks were performed twice a day, 6 days a week for 2 weeks. Two-way ANOVA with repeated measures (groups x time) was utilized (P < 0.05). Interactions were found in VO₂(max) (P = 0.011) and maximal minute ventilation (VE(max); P = 0.019). VO₂(max) (11.6%) and VE(max) (10.6%) were increased following the OCC-walk. For the cardiovascular adaptations of the OCC-walk, hemodynamic parameters such as stroke volume (SV) and heart rate (HR) at rest and during OCC-walk were compared between the first and the last OCC-walk sessions. Although no change in hemodynamics was found at rest, during the last OCC-walk session SV was increased in all five sets (21.4%) and HR was decreased in the third (12.3%) and fifth (15.0%) sets. With anaerobic power an interaction was found in anaerobic capacity (P = 0.038) but not in peak power. Anaerobic capacity (2.5%) was increased following the OCC-walk. No interaction was found in muscle strength. In conclusion, the 2-week OCC-walk significantly increases VO₂(max) and VE(max) in athletes. The OCC-walk training might be used in the rehabilitation for athletes who intend to maintain or improve endurance.
Slow-walk training combined with restricted leg muscular blood flow (KAATSU) produces muscle hypertrophy and strength gains in young men, which may lead to increased aerobic capacity and functional fitness. The purpose of this study was to investigate the effects of walk training combined with KAATSU on muscle size, strength, and functional ability, as well as aerobic capacity, in older participants. A total of 19 active men and women, aged 60 to 78 years, were randomized into either a KAATSU-walk training group (n = 11, K-walk) or a nonexercising control group (n = 8, control). The K-walk group performed 20-minute treadmill walking (67 m/min), 5 days/wk for 6 weeks. Isometric (11%) and isokinetic (7%-16%) knee extension and flexion torques, muscle-bone cross-sectional area (5.8% and 5.1% for thigh and lower leg, respectively), as well as ultrasound-estimated skeletal muscle mass (6.0% and 10.7% for total and thigh, respectively) increased (P< .05) in the K-walk group but not in the control group. Functional ability also increased significantly only in the K-walk group (P < .05); however, there was no change in the estimated peak oxygen uptake(absolute and relative to body mass) for either group. The results of the current study indicate that 6 weeks of KAATSU-walk training did not simultaneously improve cardiovascular and muscular fitness of older participants. However, it significantly increased muscular size and strength as well as functional ability of active older men and women.
To comprehensively assess the influence of aerobic training on muscle size and function, we examined seven older women (71 +/- 2 yr) before and after 12 wk of cycle ergometer training. The training program increased (P < 0.05) aerobic capacity by 30 +/- 6%. Quadriceps muscle volume, determined by magnetic resonance imaging (MRI), was 12 +/- 2% greater (P < 0.05) after training and knee extensor power increased 55 +/- 7% (P < 0.05). Muscle biopsies were obtained from the vastus lateralis to determine size and contractile properties of individual slow (MHC I) and fast (MHC IIa) myofibers, myosin light chain (MLC) composition, and muscle protein concentration. Aerobic training increased (P < 0.05) MHC I fiber size 16 +/- 5%, while MHC IIa fiber size was unchanged. MHC I peak power was elevated 21 +/- 8% (P < 0.05) after training, while MHC IIa peak power was unaltered. Peak force (Po) was unchanged in both fiber types, while normalized force (Po/cross-sectional area) was 10% lower (P < 0.05) for both MHC I and MHC IIa fibers after training. The decrease in normalized force was likely related to a reduction (P < 0.05) in myofibrillar protein concentration after training. In the absence of an increase in Po, the increase in MHC I peak power was mediated through an increased (P < 0.05) maximum contraction velocity (Vo) of MHC I fibers only. The relative proportion of MLC(1s) (Pre: 0.62 +/- 0.01; Post: 0.58 +/- 0.01) was lower (P < 0.05) in MHC I myofibers after training, while no differences were present for MLC(2s) and MLC(3f) isoforms. These data indicate that aerobic exercise training improves muscle function through remodeling the contractile properties at the myofiber level, in addition to pronounced muscle hypertrophy. Progressive aerobic exercise training should be considered a viable exercise modality to combat sarcopenia in the elderly population.