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

September 2010
Journal of Sports Science and Medicine 9(3):452-8

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PubMed

Authors:

Satoshi Fujita

Ritsumeikan University

Mikako Sakamaki-Sunaga

Nippon Sport Science University

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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.

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).

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©Journal of Sports Science and Medicine (2010) 9, 452-458

http://www.jssm.org

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

Abstract

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.

Introduction

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.

453

Methods

Subjects

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

session.

MRI-measured muscle cross-sectional area and vol-

ume

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).

Pretraining

Posttraining

BFR training on muscle and VO2max

454

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.

Results

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.

455

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

1).

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).

Discussion

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)

100

150

200

250

Exercise time (min)

VO2max (l/min)

VO2max (ml/kg/min)

Pre

Post

BFR-

training

CON-

training

BFR-

training

CON-

training

BFR training on muscle and VO2max

456

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-

RT.

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.

457

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.

Conclusion

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.

Acknowledgements

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.

References

Abe, T., DeHoyos, D.V., Pollock, M.L. and Garzarella, L. (2000) Time

course for strength and muscle thickness changes following up-

per and lower body resistance training in men and women.

European Journal of Applied Physiology 81, 174-180.

Abe, T., Yasuda, T., Midorikawa, T., Sato, Y., Kearns, C.F., Inoue, K.,

Koizumi, K. and Ishii, N. (2005) Skeletal muscle size and circu-

lating IGF-1 are increased after two weeks of twice daily

“KAATSU” resistance training. International Journal of

KAATSU Training Research 1, 6-12.

Abe, T., Kearns, C.F. and Fukunaga, T. (2003) Sex differences in whole

body skeletal muscle mass measured by magnetic resonance

imaging and its distribution in young Japanese adults. British

Journal of Sports Medicine 37, 436-440.

Abe, T., Kearns, C.F. and Sato, Y. (2006) Muscle size and strength are

increased following walk training with restricted venous blood

flow from the leg muscle, Kaatsu-walk training. Journal of Ap-

plied Physiology 100, 1460-1466.

Abe, T., Sakamaki, M., Fujita, S., Ozaki, H., Sugaya, M., Sato, Y. and

Nakajima, T. (2010) Effects of low-intensity walk training with

restricted leg blood flow on muscle strength and aerobic capac-

ity in elderly subjects. Journal of Geriatric Physical Therapy

33, 34-40.

Bell, G.J., Syrotuik, D., Martin, T.P., Burnham, R. and Quinney, H.A.

(2000) Effect of concurrent strength and endurance training on

skeletal muscle properties and hormone concentrations in hu-

mans. European Journal of Applied Physiology 81, 418-427.

Coffey, V.G. and Hawley, J.A. (2007) The molecular bases of training

adaptation. Sports Medicine 37, 737-763.

Denis, C., Chatard, J.C., Dormois, D., Linossier, M.T., Geyssant, A. and

Lacour, J.R. (1986) Effects of endurance training on capillary

supply of human skeletal muscle on two age groups (20 and 60

years). Journal of Physiology (Paris) 81, 379-383.

Fujita, S., Abe, T., Drummond, M.J., Cadenas, J.G., Dreyer, H.C., Sato,

Y., Volpi, E. and Rasmussen, B.B. (2007) Blood flow restric-

tion during low-intensity resistance exercise increases S6K1

phosphorylation and muscle protein synthesis. Journal of Ap-

plied Physiology 103, 903-910.

Fry, C.S., Glynn, E.L., Drummond, M.J., Timmerman, K., Fujita, S.,

Abe, T., Dhanani, S., Volpi, E. and Rasmussen, B.B. (2010)

Blood flow restriction exercise stimulates mTORC1 signaling

and muscle protein synthesis in older men. Journal of Applied

Physiology 108, 1199-1209.

Gaesser, G.A. and Rich, R.G. (1984) Effects of high- and low-intensity

exercise training on aerobic capacity and blood lipids. Medicine

and Science in Sports Exercise 16, 269-274.

Gollnick, P.D., Armstrong, R.B., Saltin, B., Saubert, C.W. 4th, Sem-

browich, W.L. and Shepherd, R.E. (1973) Effect of training on

enzyme activity and fiber composition of human skeletal mus-

cle. Journal of Applied Physiology 34, 107-111.

Harber, M.P., Konopka, A.R., Douglass, M.D., Minchev, K., Kaminsky,

L.A., Trappe, T.A. and Trappe, S. (2009) Aerobic exercise

training improves whole muscle and single myofiber size and

function in older women. American Journal of Physiology 297,

R1452-R1459.

Hass, C., Garzarella, L., de Hoyos, D.V., Connaughton, D.P. and Pol-

lock, M.L. (2001) Concurrent improvements in cardiorespira-

tory and muscle fitness in response to total body recumbent

stepping in humans. European Journal of Applied Physiology

85, 157-163.

Hoppeler, H. (1986) Exercise-induced ultrastructural changes in skeletal

muscle. International Journal of Sports Medicine 7, 187-204.

Hurley, B.F., Seals, D.R., Ehsani, A.A., Cartier, L.J., Dalsky, G.P.,

Hagberg, J.M. and Holloszy, J.O. (1984) Effect of high-

intensity strength training on cardiovascular function. Medicine

and Science in Sports Exercise 16, 483-488.

Jones, D.A. and Rutherford, O.M. (1987) Human muscle strength train-

ing; the effects of three different regimens and the nature of the

resultant changes. Journal of Physiology 391, 1-11.

Kraemer, W.J., Patton, J.F., Gordon, S.E., Harman, E.A., Deschenes,

M.R., Reynolds, K., Newton, R.U., Triplett, N.T. and Dziados,

J.E. (1995) Compatibility of high-intensity strength and endur-

ance training on hormonal and skeletal muscle adaptations.

Journal of Applied Physiology 78, 976-989.

Luthi, J.M., Howald, H., Claassen, H., Rosler, K., Vock, P. and Hop-

peler, H. (1986) Structural changes in skeletal muscle tissue

with heavy-resistance exercise. International Journal of Sports

Medicine 7, 123-127.

MacDougall, J.D., Sale, D.G., Moroz, J.R., Eleder, G.C.B., Sutton, J.R.

and Howald, H. (1979) Mitochondrial volume density in human

skeletal muscle following heavy resistance training. Medicine

and Science in Sports 11, 164-166.

Manini, T.M. and Clark, B.C. (2009) Blood flow restricted exercise and

skeletal muscle health. Exercise and Sports Science Review 37,

78-85.

McCarthy, J.P., Agre, J.C., Graf, B.K., Pozniak, M.A. and Vailas, A.C.

(1995) Compatibility of adaptive responses with combining

strength and endurance training. Medicine and Science in Sports

Exercise 27, 429-436.

Nelson, R.R., Gobel, F.L., Jorgensen, C.R., Wang, K., Wang, Y. and

Taylor, H.L. (1974) Hemodynamic predictors of myocardial

oxygen consumption during static and dynamic exercise. Circu-

lation 50, 1179-1189.

Nygren, A.T., Sundberg, C.J., Goransson, H., Esbjornsson-Liljedahl, M.,

Jansson, E. and Kaijser, L. (2000) Effects of dynamic ischaemic

training on human skeletal muscle dimensions. European Jour-

nal of Applied Physiology 82, 137-141.

Ozaki, H., Brechue, W.F., Sakamaki, M., Yasuda, T., Nishikawa, M.,

Aoki, N., Ogita, F. and Abe, T. (2010) Matabolic and cardio-

vascular responses to upright cycle exercise with leg blood flow

reduction. Journal of Sports Science and Medicine 9, 224-230.

Park, S., Kim, J.K., Choi, H.M., Kim, H.G., Beekley, M.D. and Nho, H.

(2010) Increase in maximal oxygen uptake following 2-week

walk training with blood flow occlusion in athletes. European

Journal of Applied Physiology 109, 591-600.

Schwartz, R.S., Shuman, W.P., Larson, V., Cain, K.C. and Fellingham,

G.W., Beard, J.C., Kahn, S.E., Stratton, J.R., Cerqueira, M.D.,

Abrass, I.B. (1991) The effect of intensive endurance exercise

training on body fat distribution in young and older men. Me-

tabolism 40, 545-551.

Seynnes, O.R., de Boer, M. and Narici, M.V. (2007) Early skeletal

muscle hypertrophy and architectural changes in response to

high-intensity resistance training. Journal of Applied Physiology

102, 368–373.

Sundberg, C.J. (1994) Exercise and training during graded leg ischaemia

in healthy man. Acta Physiologica Scandinavica 615 (Suppl.),

1-50.

Tabata, I., Atomi, Y., Kanehisa, H. and Miyashita, M. (1990) Effect of

high-intensity endurance training on isokinetic muscle power.

European Journal of Applied Physiology and Occupational

Physiology 60, 254-258.

Takano, H., Morita, T., Iida, H., Asada, K., Kato, M., Uno, K., Hirose,

K., Matsumoto, A., Takenaka, K., Hirata, Y., Eto, F., Nagai, R.,

Sato, Y. and Nakajima, T. (2005) Hemodynamic and hormonal

responses to a short-term low-intensity resistance exercise with

the reduction of muscle blood flow. European Journal of Ap-

plied Physiology 95, 65–73.

Takarada, Y., Sato, Y. and Ishii, N. (2002) Effects of resistance exercise

combined with vascular occlusion on muscle function in

BFR training on muscle and VO2max

458

athletes. European Journal of Applied Physiology 86, 308–314.

Tesch, P.A., Komi, P.V. and Hakkinen, K. (1987) Enzymatic adapta-

tions consequent to long-term strength training. International

Journal of Sports Medicine 8(Suppl. 1), 66-69.

Tesch, P.A., Ekberg, A., Lindquist, D.M. and Trieschmann, J.T. (2004)

Muscle hypertrophy following 5-week resistance training using

a non-gravity-dependent exercise system. Acta Physiologica

Scandinavica 180, 89-98.

Wenger, H.A. and Bell, G.J. (1986) The interactions of intensity, fre-

quency and duration of exercise training in altering cardiorespi-

ratory fitness. Sports Medicine 3, 346-356.

Wilkinson, S.B., Tarnopolsky, M.A., Grant, E.J., Correia, C.E., Phillips,

S.M. (2006) Hypertrophy with unilateral resistance exercise oc-

curs without increases in endogenous anabolic hormone concen-

tration. European Journal of Applied Physiology 98, 546–555.

Wilmore, J.H., Davis, J.A., O’Brien, R.S., Vodak, P.A., Walder, G.R.

and Amsterdam, E.A. (1980) Physiological alterations conse-

quent to 20-week conditioning programs of bicycling, tennis,

and jogging. Medicine and Science in Sports Exercise 12, 1-8.

Yasuda, T., Brechue, W.F., Fujita, T., Sato, Y. and Abe, T. (2008)

Muscle activation during low-intensity muscle contractions with

varying levels of external compression. Journal of Sports Sci-

ence and Medicine 7, 467-474.

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-

pacity.

AUTHORS BIOGRAPHY

Takashi ABE

Employment

Professor, University of Tokyo, Graduate School of Frontier

Sciences, Japan

Degree

PhD

Research interest

Exercise physiology and sports performance, training science

E-mail: abe@k.u-tokyo.ac.jp

Satoshi FUJITA

Employment

University of Tokyo, Graduate School of Frontier Sciences,

Japan

Degree

PhD

Toshiaki NAKAJIMA

Employment

University of Tokyo, Graduate School of Midicine, Japan

Degree

MD, PhD

Mikako SAKAMAKI

Employment

University of Tokyo, Graduate School of Frontier Sciences,

Japan

Degree

PhD

Hayao OZAKI

Employment

University of Tokyo, Graduate School of Frontier Sciences,

Japan

Degree

MSc

Research interest

Exercise physiology, sport and training science

Riki OGASAWARA

Employment

University of Tokyo, Graduate School of Frontier Sciences,

Japan

Degree

MSc

Masato SUGAYA

Employment

University of Tokyo, Graduate School of Frontier Sciences,

Japan

Degree

MSc

Maiko KUDO

Employment

University of Tokyo, Graduate School of Arts and Sciences,

Japan

Degree

MSc

Miwa KURANO

Employment

University of Tokyo, Graduate School of Medicine, Japan

Degree

MSc

Tomohiro YASUDA

Employment

University of Tokyo, Graduate School of Frontier Sciences,

Japan

Degree

PhD

Research interest

Exercise physiology, sport science

Hiroshi OHSHIMA

Employment

Japan Aerospace Exploration Agency, Japan

Degree

MD, PhD

Chiaki MUKAI

Employment

Japan Aerospace Exploration Agency, Japan

Degree

MD, PhD

Naokata ISHII

Employment

Professor, University of Tokyo, Graduate School of Arts and

Sciences, Japan

Degree

PhD

 Takashi Abe, PhD

Graduate School of Frontier Sciences, University of Tokyo, 5-1-

5 Kashiwanoha, Kashiwa, Chiba, Japan 227-8563

Combined effect of sprint interval training and post-exercise blood flow restriction on muscle deoxygenation responses during ramp incremental cycling

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Purpose This study investigated the effect of sprint-interval training combined with post-exercise blood flow restriction (i.e., SIT + BFR) on pulmonary gas exchange and microvascular deoxygenation responses during ramp incremental (RI) cycling. Methods Nineteen healthy, untrained males (mean ± SD age: 24 ± 5 years; height: 178 ± 6 cm; body mass: 77.0 ± 10.7 kg) were assigned to receive 4 weeks of SIT or SIT + BFR. Before and after the intervention period, each participant completed a RI cycling test for determination of peak oxygen uptake (V˙O2peak

\dot {\text{V}}\text{O}_{\text{2peak}}

) and the gas exchange threshold (GET) with deoxygenated heme (Δdeoxy[heme]) and tissue oxygenation index (TOI) measured by near–infrared spectroscopy (NIRS) in vastus lateralis (VL) muscle. Results Relative V˙O2peak

\dot {\text{V}}\text{O}_{\text{2peak}}

increased by 7% following both interventions (P ≤ 0.03). SIT + BFR increased peak Δdeoxy[heme] when normalized relative to leg arterial occlusion (PRE: 57.3 ± 13.0 vs. POST: 62.0 ± 13.2%; P = 0.009) whereas there was no significant difference following SIT (PRE: 64.9 ± 14.3 vs. POST: 71.4 ± 11.7%; P = 0.17). Likewise, TOI nadir decreased at exhaustion following SIT + BFR (PRE: 56.9 ± 9.1 vs. POST: 51.4 ± 9.2%; P = 0.002) but not after SIT (PRE: 58.5 ± 7.1 vs. POST: 56.3 ± 8.2%; P = 0.29). The absolute cycling power at the GET increased following SIT + BFR (PRE: 108 ± 13 vs. POST: 125 ± 17 W, P = 0.001) but was not significantly different following SIT (PRE: 112 ± 7 VS. POST: 116 ± 11 W, P = 0.54). Conclusion The addition of post-exercise BFR to SIT alters the mechanism underlying the enhancement in V˙O2peak

\dot {\text{V}}\text{O}_{\text{2peak}}

by increasing the peak rate of muscle fractional O2 extraction in previously untrained males.

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Background: Evidence suggests that aerobic training with blood flow restriction is beneficial for treating fibromyalgia. This study evaluated the feasibility, safety, and effects of an aerobic training program with blood flow restriction for women with fibromyalgia. Methods: Thirty-seven women with fibromyalgia were included, and thirteen with an average age of 59 ± 3, a BMI of 26 ± 3, and who were polymedicated started the intervention period. The intervention group performed aerobic exercise with blood flow restriction using occlusive bands placed in the upper part of the rectus femoris, with a total duration of 14 min of restriction divided into two periods of 7 min with a rest period of 3 min and a total session duration of 17 min. Pressure intensity was measured using the visual pain scale (VAS), scoring 7 out of 10 (n = 7). The non-intervention group performed aerobic exercise without restriction of blood flow for the same periods, rest periods, and total duration of the session (n = 6). The intervention included 2 weekly sessions with 72 h between aerobic walking for 9 weeks. Walking was measured individually using the rating of perceived exertion scale (RPE) with an intensity between 6 and 7 out of 10. Visual and verbal support for the VAS and RPE scale was always provided throughout the sessions supervised by the investigator. Functional capacity was assessed using tests (six-minute walk test, incremental shuttle walk test, knee extension and handgrip test by dynamometer, 30 s chair stand test, and timed up-and-go test). Symptomatology was assessed using questionnaires (Widespread Pain Index, Symptom Severity Score, Fibromyalgia Impact Questionnaire, and Multidimensional Fatigue Inventory), and blood samples were collected. Results: There were no adverse effects, and only one participant in the intervention group withdrew. Between-group and intragroup differences showed that the intervention group obtained improvements in the functional tests; CST p = 0.005; 6MWT p = 0.011; Handgrip p = 0.002; TUGT p = 0.002 with reduced impact of the disease according to the questionnaires; FIQ Stiffness p = 0.027 compared with the nonintervention group. Biochemical results remained within normal ranges in both groups. Conclusions: Blood flow-restricted aerobic training may be feasible, safe, and more effective than unrestricted aerobic training as a physical exercise prescription tool to improve cardiorespiratory fitness, strength, balance, and stiffness in women with fibromyalgia.

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J SPORT SCI

This study examined the effects of blood flow restriction (BFR) on motor unit (MU) behaviour of the biceps brachii (BB) during a single non-exhausting submaximal muscle action. Twenty adults performed maximal voluntary contractions (MVCs) of the elbow flexors, followed by an isometric trapezoidal muscle action at 40% MVC during BFR and control (CON) visits. Surface electromyographic signals recorded from the BB during the 40% MVCs were decomposed. Recruitment thresholds (RTs), MU action potential amplitudes (MUAPAMPS), initial firing rates (IFRs), mean firing rates (MFRs) at steady force, and normalized EMG amplitude (N-EMGRMS) were analysed. Y-intercepts and slopes were calculated for the MUAPAMP, IFR, and MFR vs. RT relationships. Y-intercepts for the IFR and MFR vs. RT relationships and N-EMGRMS increased during BFR (p < 0.05) collapsed across sex. The slopes for the IFR and MFR vs. RT relationships decreased during BFR (p < 0.05) collapsed across sex. The y-intercepts and slopes for the MUAPAMP vs. RT relationships were not different (p > 0.05) between treatments or sex. BFR during the 40% MVC increased IFRs, MFRs, and N-EMGRMS. However, the similar MUAPAMPS observed between treatments may suggest that a greater load is necessary to recruit additional MUs when performing a single submaximal short-duration muscle action with BFR.

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INT J MOL SCI

Blood flow restriction exercise has emerged as a promising alternative, particularly for elderly individuals and those unable to participate in high-intensity exercise. However, existing research has predominantly focused on blood flow restriction resistance exercise. There remains a notable gap in understanding the comprehensive effects of blood flow restriction aerobic exercise (BFRAE) on body composition, lipid profiles, glycemic metabolism, and cardiovascular function. This review aims to explore the physiological effects induced by chronic BFRAE. Chronic BFRAE has been shown to decrease fat mass, increase muscle mass, and enhance muscular strength, potentially benefiting lipid profiles, glycemic metabolism, and overall function. Thus, the BFRAE offers additional benefits beyond traditional aerobic exercise effects. Notably, the BFRAE approach may be particularly suitable for individuals with low fitness levels, those prone to injury, the elderly, obese individuals, and those with metabolic disorders.

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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).

Compatibility of adaptive responses with combining strength and endurance training

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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

Compatibility of high-intensity strength and endurance training on hormonal and skeletal muscle adaptations

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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.

Skeletal muscle size and circulating IGF-1 are increased after two weeks of twice daily “KAATSU” resistance training

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Full-text available

Jan 2005

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.

Blood flow restriction exercise stimulates mTORC1 signaling and muscle protein synthesis in older men

Article

Full-text available

Feb 2010
J APPL PHYSIOL

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.

Human muscle strength training: The effects of three different regimes and the nature of the resultant changes

Article

Nov 1987

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.

Increase in maximal oxygen uptake following 2-week walk training with blood flow occlusion in athletes

Article

Jul 2010
EUR J APPL PHYSIOL

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.

Effects of low-intensity walk training with restricted leg blood flow on muscle strength and aerobic capacity in older adults

Article

Jan 2010
J Geriatr Phys Ther

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.

Aerobic exercise training improves whole muscle and single myofiber size and function in older women

Article

Aug 2009
AM J PHYSIOL-REG I

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.