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

Authors:

Abstract

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.
筋サイズと循環IGF−1は2週間の加圧筋力トレーニング後に増加した(英文)
安部孝、安田智洋、緑川泰史、佐藤義昭、Charles F. Kearns、井上浩一、小
泉 潔、石井直方
Skeletal muscle size and circulating IGF−1 are increased after two weeks
of twice daily  ‘‘KAATSU”  resistance training
(lnternational Journal of Kaatsu Training Research 1(1): 6−12, 2005)
●D    ▲  ▲・
Skele拍l muscle size ond circu』fing IGF−10re increosed
。6er柵。 weeks。揃ce ddly”KAATSU”resis†。nce
          
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                  。臼・R州wiあ・e・†・idi・n・}m・・cubr ven。u・bl。。d}1。w{n。m・ly”UT−K。。↑su”fr。ining}{。・細。 week・
                  on skelefql muscle size qnd circulofing insuIh・hke grow↑h}ocfor・1{lGF・η. Nineγoung men
                  per}。rmed LIT・Kqdsu qnd se∨en men perら・md UT。1。ne. Tr。ining wq・c。・ducf・d h〃・fime・/d。y,
                  six doys/week}or 2 weeks using 3 se†s o臼wo dynomic exercises{scluα†ond leg curl}.♪λuscle cross・
                  sedionql qre◎{CSA}clnd volume were meqsured by mogne↑ic resononce imoging qf boseline ond 3
                  doys oher由e los††rqining session{pos†寸esfing}.∼1id㌔igh muscle・bone CSA wos cqkしlofed from
                  fhigh gir宙qnd odipose fissue fhickness, which were meqsured every mornhg prior b由e†roining
                  session. Serum IGF・1 concen↑rofion wos meosured o†bqseline, mid・poinf o臼he froining ond posf.
                  †esfing. lncreoses in squo†{17%}ond leg curl{23%}one・RM sfrengfh in佑e UT・Koofsu were higher
C。rrespondence}o:     {p<O.05}宙on fhose of fhe UT{9%ond 2%1. There wos o grqduol increαse in circulqfing IGF・1αnd
繊騒i鷲,弓蕊蒜灘.襯5㍑==1跳艦雪嬬荒瀧
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。beb㊨c。mp・melr。燗c・iP s胎ngfh{仁酬/mu叉le CSA}be∼ゾeen bqseline qnd posト↑esfing in bdh groups, We c◎ncluded↑hqf
㌫口口;lll亘…’◆”・kr1瓢d m・・c1・hγP・・f・・phγ。・d・r・eng↑h gd・。・・∪・・ed。6・・榊・week・。}細i・e d。ily肝㎞・†・u
oulhors’q仔il|oh◎ns        ↑rOmmg・
,........_.._.,.._... @Key word5:muscle hγperfrophy,↑rαining frequencγ, muscle vobme, mqgnefic resonqnce imoging
lNTRODUC’「ION                 increases m musde CSA as traditional high−intensity
  Human skeletal musde is respollsive to acute and resistance traming(HIエ80%of 1−RM>and∼3 times
chronic stimuli associated with resistance training. the growth honnone(GH)secretion as HIT[Kraemer
The na加re of the phenotypic adaptation is dependent  et aL,‘1991;Takarada et al.,2000a;Viru et al.,1998].
upon how the specific variables of the resistance− Interestingly LIT・Kaatsu does not require a long
trainillg regi111e (training intensityン volulne,   recovery thne between trair直ng sessiolls[Abe,2004]
frequencソand recovery etc.)are colnbined. Several due to very low mechanical stress and minimal
sode6es IACSM,1998;NSCA,2003】have published muscle damage[Takarada et al.,2000a】produced
their guidelines for optimizing muscle hypertrophy when a load of only 20%of 1・RM is used. Therefore,
and strength gains. In gene ral, a trair血〕g inter路ity of hgh frequency training is possible with LIT−Kaatsu
over 65%of one repetition maximum(1・RM)is training. In the previous HIT studies[Abe et al.,
required to a(沌eve substantial musde hypertrophy   2000;Jones and Ratherford,1987;Staron et al.,
【Campos et al.,2002;Kraemer et al.,2004; 1991], sllbstan6al musde hypertrophy was observed
McD onagh et al.,1984]. Training below an intensity  after apProximately 24 sessior岱of the trainjng(e.9.,8
0f 65%of 1−RM rarely produces increases in musde weeks and 3 days per week). We hW〕othesized that
size or strength【Kraemer et al.,2004]. In contrast, substantial muscle hypertrophy may be achieved
previous published studies have reported that low・ following a short period of high frequency HTKaatsu
intensity resistance trainillg(LI肥20−50%of 1・RM) training. Thus, the p町)ose of this study was to
combtned with restriction of muscular venous blood  inves6gate the effects of twice daily sessions of U工
flow(namely”口T−Kaatsu”training)can incre ase Kaatsu trair血g for two weeks(6 days/week, total
muscle cross・sectional area(CSA)and strength in  24 sessions>on skeletal lnusde size and circulating
nlen[Burgomaster et al,,2003;Shinohara et aL, insulin−hke growth factor・1(IGF・1)level.
1998;宜karada et al.,2002]and women[Takarada et
al.,2000b], The][JT−Kaatsu trairUllg produces s㎞ilar
T,Abe, T. Yqsudq, T・♪Aidorik(w(】, e↑ol・                                                                 7
M日HODS                   training time)and was released ilnlnediately upon
sobieds            c・mple60n of the sessio江皿・e LIT gro・lp Pe㎡・nned
  Sixteen healthy men[mean(SD)age 23.6(65) the same exercises at the same intensity but withotlt
years, height 172.4(65)cm, body mass 64.3(9.8) the res耐(丈ion of muscular blood flow.
kg】volunteered to participate in the study・All
su句ects led a(丈ive lives, with 80f l 6 participating in  Mdximom sfnmgfh meoswemen胎
regular aerobic exercise. Howeveちnone of the   One week prior to training, the subjects were
s11句ects had participated in a regular resistance familiarized with testing and training equipment.
exerdse prograln for at least 6 months prior to the  Pr(互)er lifting technique was demor岱trated for each of
start of the study. The subjects were randomly  the two exerdses(squat and leg cud>and all su均ects
divided into two training groups:alow・intensity perfonned practice h危s prior to attelnpting maxhllal
resistance training with Kaatsu(restriction of lifts. Maximllm dynamic strength(1・RM)was
muscular venous blood flow)group[LIT・Kaatsu, assessed prior to(base丘ne)and 3 days after the五nal
1ユ=g]and a low・intensity resistance training vvithout training(post−testing)for each exercise. After
Kaatsu grollp【皿, n=7]・All s両ec鱈we副㎡onned wa㎜illg up, the load was set at 80%of the pre直cted
of the procedures,亘sks, and bene登ts, and signed an  1−RM. Following each successflll lift the load was
informed consent document before participation. increased by∼5%ur柱il the sublect failed to liR the
The study was apProved by the Ethics Comlnittee for load through the entire range of mo口on, A test was
Human Expenments, Tbkyo Metr(遷)olitall Umversity  considered vahd o1ゴy when the sul刀ect uSed pr(享)er
                                             form and completed the entire lift in a controlled
T悶治ing probcol                  lnanner without assistance. On average,避ve t亘als
  The s叫lects in both LIT−Kaatsu and LIT groups were required to complete a I−RM test.
par6cipated in two weeks of supervised resistance  Approximately 2−3 min of rest was allotted between
training. Training was conducted twice per day  each attempt to er岱ure recovery(Abe et aL,2000).
(morning and afternoon sessions, with at least 4
hours between sessions)for 12 consecutive days Moscle−bone cross−secfioml oreo es†imofion
{exdudi㎎one Sunday). FolloWg a wa㎜up, the An anthropometric method(Mid・thigh C SA=
su旬ects pe㎡o㎜ed 15 repetitions of squat and leg π[r・(Q一坦+H一虹)ノ2]2)was used to estimate血e
curl exercises using an isotonic training machine  mllsde−bone cross・sectional area(CSA)for血e mid−
(Nippyo). The tntensity of exerdse was 20%of 1・RM  d並gh[α1mey and Jelliffe,1973]. Where r was dle
for both LIT・Kaatsu and LIT groups. The su句ects  radius of the thigh cakulated from IIUd−thigh girth of
performed three sets of exercise in each exercise  the right leg, Q−AT and H・AT were ultrasound−
session, with 30 seconds rest between sets and measured[Abe et al.,1994]anterior and posterior
exercises. The exercise intensity was determined  thigh adipose tissue thickness, respectively. The
during the initial stage of training and remained  est口孤ated CV of thjs measurement was 1.2%. This
constant for the duration of the training period. A  measurement was carried out each morning prior to
speciaUy designed elastic belt(Sato Sports Plaza Ltd.,  the training session and p亘or to the post−testing.
Tbkyo, Japan>was placed around the lnost proxmlal
P・蜘n・fb・d・legs dudng d・e exercise session in tlユe B。dy c。mp。siH。n
HTKaatsu group[Takarada et al.,2002L The belt  Body density was measured by the hydrostatic
contailled a small pneumatic bag along its iymer weighing technique with simultaneous lneasure111ent
su㎡ace that was co㎜ected to an electro血c pressure of residual lung volulne by oxygen diIution at
gauge that monjtored the restnction pressure(MPS− base㎞e and post−tes6ng[Abe et al.,1994]. B ody fat
700,VINE, Tbkyo, Japan). On Day 1, the cuff percentage was calculated from the body density
pressure was l 60 mmHg and the pressure was us祖g the equation of Brozek et al[1963], Faレfree
increased 10 mmHg each day until a final training mass was estimated as body mass mmus fat mass.
cuff pressure of 2401nlnHg was reached, The cuff
pressure of∼240 mmHg was selected for the MRI−medsured muscle CSA ond volume
ocdusive sHmulus as this pressure has been stlggested  Magnetic resonance imaging(MRI)hnages were
to restrict venous blood flow and cause pooling of prepared using a General刊ectric Signa 1.5 Tesla
blood in capacitance vessels distal to the cuff, and scanner(Milwaukee, Wisconsin, USA). A Tl
lUt㎞ately restricts artenal blood now[聡karada et al., weighted, spin echo, axial plane sequence was
2000b;Takarada et al.,2002]. The estimated  perfonユ1ed with a 1500 millisecond repetition time
coefficient of variation(CV)of this pressure  and a 17 millisecond echo time. Sllbjects rested
measurement was 2.2%. The restric60n of muscular quietly in the magnet bore in a supine position widl
blood flow was maintained for the elltire exercise their legs extended, The intervertebral space between
sessio11〈inchlding rest periods, abollt 10min total the fburth and舳h lumbar vertebrae was used as th.e
8                                               ∼tuscle hγperlrophy飴lbwing「wo weeks of K〈101su lroin言ng
origin I)oint and contiguous transverse㎞age s with commercially available radiohnmunoa ssay〈Da]]℃姐
1.O cm slice thickness(O cm i nte rs]ice gap)were Radioisotope LaboratcrソChiba, Japan),
d)tained from the fi血1ユ1ulnbar vertebrae to the ankle
joints for eacll sllbject. A]]MRI scans were SloHsficol Ano1γses
seglnented into four components(skeletal muscle,  Results are expressed as lneans±standard
subα1taneolls adipose tissue, bone, and residual deviations(SD)for all va亘ables. A two−way ANOVA
tissue)by a high]y trained analyst, and the1ユtraced. with repeated−measures(group alld time)was
For each slice, the skeletal mllscle tissue CSA was utiHzed to evaluate the effect ohhe Kaatsu tra汕ng
digitized, and the 111usde dssue volmne〈(ユn3}per slice   independent of the chalユges ill the Lrr alolle, Pos8−
was calculated by mllltiplying muscle tissue area hoc testing was perfcrmed by a Flsher’s正east
(cm2)by shce thic㎞ess(αn). Musde volume of the significant differences test, Baseline differences
indi趣al musde was de五ned as血e sun㎜ation of between UT・Kaatsu and UT and percen白ge changes
the slices of m.11scle・Tlle estimated CV of this betwee1ユbaseline and post−tes目ng were evaluated
measurement was 2.1%[Abe et aL、2003】. The with a one−way analysis of varia1ユce{ANCVA),
average value of the nght arld Ieft sides of the body  Sta6stical sigr曲cance was set at P<0.05.
was used、 This measurement was completed at
baseline and posレtesting                 RESU t1「S
                                           Boseline meosuremen恒
Blood sompling ond biochemicq』nolyses      There were no statis6cally sigヱ茄callfdifferences虹1
  Venous blood was drawn fro皿each su句ect at th民e body composi60n, muscle−bone CSA, L RM streng亡h
time points:at baseline, at the mid・point of the  (論ble 1),1nid t姐gh musde CSA, or muscle voユu皿e
tぬi㎎,and at post−testing. AH blood samples were (聡ble 2)between U球aatsu and LIT at basdine,
obtained at the same time of day followillg an
overnight fast(12・13hours}. The sublects were  Re』†ive chonge in esHm帥ed muscle−bone CsA
counseled to refrain from ingesting alcohol arld  Muscle−bone CSA gradllally increasedΦ<0.0ユ)加
caffeine for 24 hollts pnor to bbod conection and not  the LIT Kaatsu but not ill the UT The rn usde−bone
to perform ally strenuolls exerdse except training  CSA’increased 7%at the end of the first week i」1 the
sessions. Serum IGF−1 concentrations were LIT−Kaats11. By post−testing, the musde−bone CSA
determined using a commerciaUy available had increased 9%in the IユT・Kaatsu, In口丁, musde−
radio廿mnunoassay(Daiichi Radioisotope工aborato彫  bone CSA increased 3%(p>0.05)at the eエ1d of the
Chiba, Japan), Radioactivity was nleasured using an  first week, and was similar(∼2%)to base五ne at pc51・
autonlated galnma collnter(AR C−950, Aloka,コbkyo,  testing(Figure 1).
Japan). Plasma activity of creatille phosphokinase
(CPK)was measured with spectrophotonletry for
NADPH forlned by a hexokinase and D−glucose−6−
phosphate−dehydrogenase−coupled enzymic system,                    ,      乙∫「κσσ廊ロ
Plasnユa concentratiolls of lipid peroxide and     12
畏麟=蒜霊瀧濫認㌶霊11・
thiobarbituric acid 【Yagi,1976]and using a  革  8
                                           § 6
                                           i・
翻:認羅織認蝋鑑譜㍑鵠麟ぎ・
of muscular blood now(ロT−Kaatsu)and low・intensity 寧 o
resistance tl泊ning alone(UT)gmups.
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Age〈yr)             23.9 (8.4)   23ユ (3.1)                               (day)
竃鱒km)1i㌶i)1ii;i llii鷲議灘三翻撒i撒
蒜9蹴!m) ;;:19:;1’;6:i2:ll罐劉麟㌫C鵬)麗・蹴瓢罐
竃欝鶯圃 1ii iilミ 1ii iiiミ竃竃麟講還聖毛鵠㌣謬蕪麗
T,Abe, T. Ydsu({d, T.♪Aidorikqwd, ef oL                                                               9
C卜onges in《ARLmeosured muscle(SA qnd volume  Chonges in obsolule ond relo†ive s†reng↑h
 Mid−thigh musde CSA increased(P<0.Ol)by 8.5%   Squat strength increased in both UT−Kaatsu
in the LIT・Kaatsu but not(1.8%, p>0.05)in the LIT  (16.8%, p<0.01)and UT(8.9%, p<0.05). Howeve罵
Quadriceps and biceps femoris mllscle vohlmes  legα1rl strength increased(22・6%, P<0・Ol)in the
increased (both p<0.01)7.7% and 10.1%,  LIT・Kaatsu but not(1.3%, p>0.05)in the Lrr. The
respectively in the LIT・Kaatsu but ollly l.4%and  relative percentage changes in squat and leg curl
1.9%(P>0.05),respectively in the UT GIuteus strength were larger(P<0.05)in the UT−Kaatsu
maxh皿us lnusde volume illcreased(p<0.01>9.1%in compared to the LIT{Figure 3). The l−RM squat
the LIT−Kaatsu, but did not change in the口T(・0.6%)  strength per unit quadriceps musde C SA was similar
(Figure 2 and T泣)le 2)・                       (P>0・05)at baseline and at post−testing in both
                                            groups. The 1・RM leg curl strengtll per unit
                                            hamstrings musde C SA was also similar{p>0、05)at
                                            basehne and post−train泊ユ9虹1 both groups(Figure 4).
 In the LIT−Kaatsu group, serum IGF・1 increased
progressively and reached significance(p<0.05)after
2weeks of trairUng. The民was no change(p>0.05)
in semm IGF−1 in LITσ遠ble 3).
Bi。chemicd p。r。me缶rs
 At baseline, all subjects had a nomlal CPK, lipid
peroxi de and myoglobin concentrations. D u亘ng and
(P>0.05)in both groups(Table 3).
鵠蒜,蕊1認翻鑑㌶篇’躍㌶認認・ndR・th・;f・・d f987:St…n・t由。1991;S垣・・n・t
and after(post−testing)the two weeks of low−intensity  al・,1994]have reported that a substantial mcrease in
resistance training combined with restn(戊ion of muscular skeletal muscle and fiber CSA in the thigh is not
blood flow・The image∬how identical se(戊ions, mid・way  observed eadier thall six weeks of HIT Tb the best of
along the femur in the same su句ect.
DISCUSSION
 The major垣ding of the present stUdy was that
two weeks of twice daily LIT−Kaatsu produced
increases in skeletal 111usde size(7−8%)that were
si111ilar in lnagnitude to those reported in traditional
HIT of 3・4 months[Abe et aL,2000;Jones and
Rather数)rd 1987] Previous published studies[Jolles
1bble 2. CIlanges in musde(mss−sedional area(CSA)aIld musde volume for the low−inte頭ty resi“ance
training combined with rest1ゴction of muscular blood now〈LIT−Kaatsu)and low−inten薗ty re亘stance
t]ainillg alone(UT)9roups measu1℃d befo1℃(basehne)and a血er(post−tes6ng)the training Peliod・
1皿㌧Kaatsu{N=9)                UT〈N=7)
BaseHne      Post−testing    %△    Basehne      Post−testing    %△
Mid−thigh Inusde CSA(cmユ)
QF        72,9±9,9    78.6±9.2†    8.0    72.6±9.7     73.6±8.O     L8
HAM     20.8±4.1   23.0±4.9†  10.7  21.6±4.3   21.9±4.4    15
ADD      40.1士4.6    43。2士4.3†    8.0   37.8±7.9    37.8士7.6     0.2
Total      141.3土17.8    152.9±17.1†    8.5   142.0±22.0    144,3±20.8     1.8
Musde volume(CIII3)
QF       1790±294    1924±288†    7.7   1787±:266    1809±257     1.4
BF         235±47      257±45†    10.1    239±52      244:ヒ58      1.9
GM        1602±353    1737士334†    9.1   1604±303    1594±298     −0.6
QF, quadliceps femolis;HAM, ham就1ings;ADD, a dducto1罵BF, biceps femolisl
GM,9uteus ma)dmus
†P<0.01 Base㎞e vs. Post−testil19
10                                            ∧4uscle hype市ophy}ollowing Iwo weeks oF Kqo皆su rrqining
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                            竃i曇 翼             0
    0
         LIT.Kaatsu LIT       LIT.Kaatsu UT               LIT−Kaatsu    UT     LIT−Kaatsu    UT
Figure 3. Percent change in LRM strength for the low− Figore 4. Rda柱ve 1−RM strength(squat!quadガceps CSA
intensity resistance training combined with restriction of and leg cud l hamsthngs CSA)of the low−inten田ty 1℃訂就ance
muscular bIood flow(LIT−Kaatsu, filled bars)and low− traiエUng con威)ined with restridion of muscular blood now
illtensity resistance training(LIT、 unf∬led bars)groups  〈Lrr−1くaatsu)and low−intensity resistance tra加ing(工rr)
measllred l)efore and after the tmining pe亘od.★P<0.05 UT−   groups measured befbre(basehne)and after(post−tes6ng)the
Kaatsu vs. IJT.                                 n’atnil19 Peliod.
㌔He 3. Ch・ng臼i・serum lGF−1。nd U。。d m・k・論r mus亡1・dqmqge・nd。紬憾・e s}・合in出e l酬・in†㎝・iけre・i・fqnce Wqining。。mもind w赫h
reshidbn o}mUSζubr})1◎◎d日◎W{U丁一Kqorsu)dnd bW−in}ensi}γresis}qr)ceけoining{UT)groups.
LrF−Kaatsu                         Lπ
Base逓ne      Mid−point     Pos卜testing    Basehne      Mid−point   Post−tes亘ng
IGF−1(㎎1ml)     323±38      373士98     400土75†     276土74      256±61    281±95
CPK(IU!1)        212±173      384±240     223±134      283±236      342土147    165±78
MYO(ng/ml)    59士22    74±28    64±20    63±5     65土16   62土4
LP(nmd/ml)    0,8土0.2    0.7土0.2    0.6士0.2    0.9土0,1    0.8土0.3  0.8士0.3
MYO, myoglobin;][P, hpid peroxide
†1)<0.05;Base五ne vs. Post⇔testing
our knowledge, there are no published data dlat have   trai血ユg frequency and smaller recovery penod that is
reported a significant increase in thigh muscle size possible with LI㍗Kaats11.
fbUowing o1」y tvvo weeks of HIT[Akhlla et al.,1999].  The present study showed that plasma markers for
In most of the previous studies, su句ects exercised 2・3 mllsde damage{CPK activity aIld myoglobin)and
times per week during the study thus only 46  0xidative stress(lipid peroxide)were not elevated
sessions are completed during the fi搭t 2 weeks of the  dllring or a且er the training in both UT−Kaatsu and
training. O ur subj ects, howeveL performed 24  LIT These results are consistent.with data reported
sessions of resistive exercises durillg the 2 weeks of by Takarada and colleagues[肱karada et al.,2000a],
training, OpUmal tra皿ng frequency is based on the who showed that plasma Inarkers for musde da111age
theodes of”superco1皿pensation”and”over・training”   and oxidative stress did not increase considerably
which attempt to generate the greatest growth  following acute LIT・Kaatsu exeKise.姶ken togethe耳
stimulus while still allowing for sufficient rest tlle results of the present study along with the
between exercise sessions[Kraeme島2000]. Since a  p㏄vious acute study su99est that the rapid response
trainjng intensity of 20%of 1−RM produces mi]血〕1al to skeletal musde hypertrophy IbUowing UT−Kaatsu
musde damage【Takarada et a1.,2000a], less recovery is not associated with muscle damage and/or
泣me is necessary{Abe,2004】, a1ユd therefore trairU㎎  inflammation of the mllscle as measured by the
frequency may be increased. The data from the plasma markers.
present study demonstrated that substantial skeletal  Myogenic regulatory factors and GH/IGF・1
muscle hypertrophy can occtl r more rapidly than pathway have beell in(Mcated to play血nportant roles
previously reported. This rapid time・course in  in resistance training・induced skeletal muscle
hypertrophy may be associated with the higher hypertrophy[Flori1ゴet aL,ユ9961 McPherron et aL,
T.Abe、 T. Yαsudq, T・∼∼idorikqwo, e†ol・                                                       11
1997].In line with these observa目011s, two weeks of training[Yasuda et aL,2004】.
LIT−Kaatsu training Produced a 24%increase in    There were no statistical challges in relative
circulating IGF・1 and tlユis change was similar in  strengtlユalld the lnagnitude of the changes were
1皿agnitude to the elevation in cirα11atillg IGF・1  relatively slnall compared to previous stre1ユgth
Ibllownlg HIT[Borst et al.,200L Marx et aL,2001]. tra口Ung smdies[Narici et al.,1996】. Howeve£this
Moreove£the elevation in circulating GH 15−min  was consistent with previolls口T・Kaatsu studies
followmg LIT・Kaatsu exercise is elevated∼3・fold  【Takarada et al.,2000b;Takarada et aL,2002].
larger than the increase in GH following HIT  Increases in relatjve strength during resistallce
{]Krae1皿er et al.,1991:Takarada et aL,2000a;Viru et  tra血ゴng, particulady the eady phase of the tra血亘ng is
al.,1998]. The resistance training−induced increase in hglUy variable and su句ect to much debate. For the
GH has been reported to increase hepatic production  most part, neural activation mcreases with training
of IGF’1 and reslllts in elevated circulating IGF−1. [Modtani and de V亘es,1979], howeve£this is not
Circulati㎎IGF−1 st血nulates musde protein synthesis always true and extremely well motivated s u句ects
[Borst et al.,200L Marx et aL,2001], In addi60n, often display full motor unit ac6vation, even before
drculating GH direcdy s6mulates endogenous muscle training[Nanci et al.,1996]. Ad(翫ional facto搭may
production of IGF・1[Flohni et al,,1996]. The refore.  con垣1)ute to the increase in relative strength, such as
the increase in circulating IGF・1 may have changes in the co−contraction of the antagonist
contributed to musde hypertmphy and stre㎎th gains musdes, density of co]並ractile elements, the muscle
during the two weeks of twice daily LIT−Kaatsu  architecture and/or increases in motor unit
traini㎎.                  synchronizati皿of the trained musdes[Nadci et al.,
  An interesting and s叫Prising nnding of the present  1996]. Su句ects in the present study apPeared weU
study was that LIT−Kaatsu training−induced muscle motivated, but it is unclear whether antagonist co・
hypertrophy occurred not only in the thigh muscle activation and/or motor ullit synchrollization are
but also in the gluteus maximus musde. Dunng the altered in response to low intensity(20%of 1−RM)
squat exercise, mairdy the knee and hip extensor resistance training with blood now restriction.
muscles are activated. Since a training intensity of   In conclusion, two weeks of twice−daily LIT−Kaatsu
20%of 1−RM was used in the present study it would produced increases in skeletal lnuscle size that were
seem reasollable that the load on the gluteus si皿ilar in magrUtude to those reported in traditional
maximus muscle during the squat would be HIT of 3・4 months. Increases in circulating IGF・1
insufficient to produce the muscle hypertrophy.  may have contributed to the skeletal muscle
However, this was not the case as significant hypertrophy and strengtll gain. Therefore we
hypertrophy was observed in the ghlteus maximus. concluded that skeletal muscle hypertrophy and
The reasons for the Inuscle hypertrophy of the  strength gaill occurred after two weeks of twice daily
gluteus maxtmus muscle after the LIT・Kaatsu are  UT−Kaatsu train血g.
unclea葛but several possibilities exist. D unng LI雅
Kaatsu exercise, high lactate accumulation ill the
mllsde fibers{聡karada et al.,2000bl of exe江ised ACKNOWLEDG酬ENIS
thigh muscles may inhibit m usα11ar contractio11.  The autho搭thank the sttldents who parUdpated in
Consequentlソadditional motor unit recrui加ent may this snldy We also thank the Sato KAATSU TrairU㎎
be reqllired in order to 1〕ユaintain sufficient force Research Follndation(to NI>and the Ministry of
generation. Previously pllblished studies have  Education, Science, Sports and Culture of Japan
reported  that  the  mean  integrated  (Grant#15300221 to TA)for their generous support.
electromyographical 111uscle activity during LIT−
Kaatsu is ahnost eqllal to that of HIT{80%of 1−RM)
Subsequently, additional motor units would be Abe T, DeH◎yos D>, Poll㏄k ML, G。rzqrelb U2000}Time course{6r
recruited by the hip muscles and this could explain   sfreng}h ond muscle拓ickness chqnges}olbwing upper dnd lower b◎dγ
the musde hypertrOphy seen i【1 the glutells maximus resis1。nce『qining h men°nd w°men・Eu「」APPI Ph)傳i 81:174’180・
flbers demonstrated a larger degree of hypertrophy qbs貯。d}.」Trdning Sci&e忙Sp◎汁16:1gg.207.
than the slow−twitch fibers foUowing LIT・Kaatsu  Aki㎜H, Tokqhqsh出, Kun。 s, sugo Y、∼∼dsudq K, M。sudq T, shimoii
12                 M・・cl・h>戸市。P伍γ㎞II。wing掘。 w⊇。F K。蜘価訂i噌
H、Anno l,1拍iゾKo捻u}o S{1999}E(1dy phose odqp80Wons of muscle use  Conli Ml, Cerrerelli P{1996)Humon qood riceps crossづec†iom l oreg、
ond sh博ngrh b isokine6c woinin9∼led Scl Sp◎rls Exerc 31:588−594    brque qnd neurol oc†ivq60n duri ng 6 mon也s swengt翫troining. Acrq
Amerkqn College o‘Sp◎r飴]Medici n阜{1998}Pbsifion Slロnd, The  Ph怜bl Scdnd 157:175−186.
recommend6d(1uqnrify qnd quo{i1γo千exercise lbr developmg ond   Nofionol Sl陀ng}h¢md(ondilioni坤g Ass・◎鴫㎞↑ion{2003)NSCA’5
moi耐oining cqrdiorespirobry ond musculdr 61ness, ond}lexib晦h  Essenhols o}Personol Trq|而ng、 edi閥bγEorle RW omd Bqechle百R,
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of b◎dy(omp◎si8ion:Re肩sion of s◎me quon6fq目ve(1ssumpWons Am NY   Hogermon FC、 Hikiro RS{1991, Sfremgfト(md skele拍I moscle
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... Low intensity resistance exercise combined with blood flow restriction (BFR) has been shown to improve muscle strength and mass (Abe et al., 2005;Laurentino et al., 2012;Bjørnsen et al., 2019); however, a meta-analysis by Lixandrão et al. (2018) suggests that BFR training stimulates similar gains in muscle hypertrophy but smaller increases in strength compared to traditional high intensity resistance training intensity (≥65% 1 repetition maximum, 1RM). This type of training program may be beneficial for individuals who have difficulty performing high intensity resistance exercise, such as those with chronic diseases such as multiple sclerosis, osteoporosis, and osteoarthritis (Freitas et al., 2021). ...
... Possible mechanisms for the adaptations that occur with BFR exercise include enhanced metabolic stress resulting from the accumulation of metabolic by-products in the occluded limbs affecting fast-twitch motor unit recruitment and the secretion of hormones and factors that promote protein synthesis and angiogenesis (Takarada et al., 2000;Suga et al., 2012;Karabulut et al., 2014). Acute bouts of BFR resistance exercise stimulate increases in blood lactate and anabolic hormones (e.g., growth hormone, testosterone, insulin-like growth factor-1, IGF-1) with minimal changes in muscle damage markers (Takarada et al., 2000;Abe et al., 2005;Takano et al., 2005;Madarame et al., 2010;Manini et al., 2012;Yinghao et al., 2021). Another mechanism is the activation of localized chemoreceptors and exercise-induced muscle swelling, often observed following BFR exercise, that may play a role in shifting the protein balance toward anabolism. ...
... Acute bouts of BFR resistance exercise have been shown to stimulate significant increases in testosterone (Madarame et al., 2010;Yinghao et al., 2021) and IGF-1 (Takano et al., 2005;Madarame et al., 2010;Yinghao et al., 2021) serum concentrations; however, the hormone adaptations to chronic BFR resistance training are not clear. Abe et al. (2005) reported a significant increase in resting serum IGF-1 concentrations after 2 weeks of BFR resistance training in young men, whereas Karabulut et al. (2013) found no significant changes in resting IGF-1, testosterone, or insulin-like growth factor binding protein-3 (IGFBP-3) serum concentrations in response to 6 weeks of either low intensity BFR or high intensity resistance training in older men. Also, the effects of BFR training programs on acute hormone responses to single bouts of resistance exercise have not been established. ...
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In this study, we compared acute and chronic bone marker and hormone responses to 6 weeks of low intensity (20% 1RM) blood flow restriction (BFR20) resistance training to high intensity (70% 1RM) traditional resistance training (TR70) and moderate intensity (45% 1RM) traditional resistance training (TR45) in young men (18–35 years). Participants were randomized to one of the training groups or to a control group (CON). The following training programs were performed 3 days per week for 6 weeks for knee extension and knee flexion exercises: BFR20, 20%1RM, 4 sets (30, 15, 15, 15 reps) wearing blood flow restriction cuffs around the proximal thighs; TR70, 70% 1RM 3 sets 10 reps; and TR45, 45% 1RM 3 sets 15 reps. Muscle strength and thigh cross-sectional area were assessed at baseline, between week 3 and 6 of training. Acute bone marker (Bone ALP, CTX-I) and hormone (testosterone, IGF-1, IGFBP-3, cortisol) responses were assessed at weeks 1 and 6, with blood collection done in the morning after an overnight fast. The main findings were that the acute bone formation marker (Bone ALP) showed significant changes for TR70 and BFR20 but there was no difference between weeks 1 and 6. TR70 had acute increases in testosterone, IGF-1, and IGFBP-3 (weeks 1 and 6). BFR20 had significant acute increases in testosterone (weeks 1 and 6) and in IGF-1 at week 6, while TR45 had significant acute increases in testosterone (week 1), IGF-1 (week 6), and IGFBP-3 (week 6). Strength and muscle size gains were similar for the training groups. In conclusion, low intensity BFR resistance training was effective for stimulating acute bone formation marker and hormone responses, although TR70 showed the more consistent hormone responses than the other training groups.
... The trend of elevated IGF-1 levels in the intervention group could mitigate muscle wasting via upregulation of the IGF-1/Akt/mTORC1 anabolic signalling pathway [136]. Previously, an acute increase in circulatory IGF-1 levels within 15 min of a single and after 2 weeks of blood flow restriction exercise training has been observed in healthy young men [137,138]. A similar loss of RFCSA occurred between the treatment groups, perhaps suggesting that observed elevated IGF-1 levels did not stimulate muscle protein synthesis. ...
... A similar loss of RFCSA occurred between the treatment groups, perhaps suggesting that observed elevated IGF-1 levels did not stimulate muscle protein synthesis. This could be possibly due to the levels of IGF-1 not reaching the required levels [138,139] or an intrinsic secretion of muscle IGF-1 might be a key determinant for switching on anabolic pathways [140][141][142][143]. ...
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Muscle wasting is implicated in the pathogenesis of intensive care unit acquired weakness (ICU-AW), affecting 40% of patients and causing long-term physical disability. A repetitive vascular occlusion stimulus (RVOS) limits muscle atrophy in healthy and orthopaedic subjects, thus, we explored its application to ICU patients. Adult multi-organ failure patients received standard care +/- twice daily RVOS {4 cycles of 5 min tourniquet inflation to 50 mmHg supra-systolic blood pressure, and 5 min complete deflation} for 10 days. Serious adverse events (SAEs), tolerability, feasibility, acceptability, and exploratory outcomes of the rectus femoris cross-sectional area (RFCSA), echogenicity, clinical outcomes, and blood biomarkers were assessed. Only 12 of the intended 32 participants were recruited. RVOS sessions (76.1%) were delivered to five participants and two could not tolerate it. No SAEs occurred; 75% of participants and 82% of clinical staff strongly agreed or agreed that RVOS is an acceptable treatment. RFCSA fell significantly and echogenicity increased in controls (n = 5) and intervention subjects (n = 4). The intervention group was associated with less frequent acute kidney injury (AKI), a greater decrease in the total sequential organ failure assessment score (SOFA) score, and increased insulin-like growth factor-1 (IGF-1), and reduced syndecan-1, interleukin-4 (IL-4) and Tumor necrosis factor receptor type II (TNF-RII) levels. RVOS application appears safe and acceptable, but protocol modifications are required to improve tolerability and recruitment. There were signals of possible clinical benefit relating to RVOS application.
... Low-load resistance training (20-30% 1RM) in combination with blood flow restriction (L-BFR) by an elastic designed cuff belt was originally developed in Japan in the last two decades [68,69], and it is known as KAATSU training [70] (Figure 1B). Most studies investigating L-BFR using weight machines or free weights have established that it leads to increased muscle size and strength [61,[69][70][71][72]. L-BFR differs from hemostasis by the use of tourniquets, which completely stop both arteries and veins, by moderately restricting blood flow with specially designed elastic cuff belts while pooling blood in the upper or lower extremities. ...
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Resistance training is an extremely beneficial intervention to prevent and treat sarcopenia. In general, traditional high-load resistance training improves skeletal muscle morphology and strength, but this method is impractical and may even reduce arterial compliance by about 20% in aged adults. Thus, the progression of resistance training methods for improving the strength and morphology of muscles without applying a high load is essential. Over the past two decades, various resistance training methods that can improve skeletal muscle mass and muscle function without using high loads have attracted attention, and their training effects, molecular mechanisms, and safety have been reported. The present study focuses on the relationship between exercise load/intensity, training effects, and physiological mechanisms as well as the safety of various types of resistance training that have attracted attention as a measure against sarcopenia. At present, there is much research evidence that blood-flow-restricted low-load resistance training (20–30% of one repetition maximum (1RM)) has been reported as a sarcopenia countermeasure in older adults. Therefore, this training method may be particularly effective in preventing sarcopenia.
... To date, no studies have investigated the feasibility of LL-BFR in patients suffering from GT. Interestingly, improvements on skeletal muscle hypertrophy and strength in muscle groups proximal to the cuff have been demonstrated (Abe et al., 2005;Yasuda et al., 2010Yasuda et al., , 2011Bowman et al., 2019). Additionally, it has been suggested that LL-BFR may trigger exercise-induced hypoalgesia comparable to levels seen after high intensity exercise . ...
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Introduction To date, there exists no gold standard conservative treatment for lateral hip pain due to tendinopathy of the gluteus medius and/or minimus tendon (GT), a condition often complicated by pain and disability. Higher loads during everyday activities and exercise seems to be contraindicated with GT. The purpose of this study was to evaluate the feasibility of exercise with low-loads concurrent partial blood flow restriction (LL-BFR) and patient education for patients present GT. Methods Recruitment took place at three hospitals in the Central Denmark Region. The intervention consisted of daily sessions for 8 weeks with one weekly supervised session. From week three patients exercised with applied partial blood flow restriction by means of a pneumatic cuff around the proximal thigh of the affected leg. Throughout the intervention patients received patient education on their hip condition. Sociodemographic and clinical variables were collected at baseline. The feasibility of LL-BFR was conducted by adherence to the exercise protocol and drop-out rate. Patient reported outcome measures (The Victorian Institute of Sport Assessment-Gluteal Questionnaire, EuroQol - 5 Dimensions-Visual Analogue Scale, Oxford Hip Score, Copenhagen Hip and Groin Outcome Score), maximal voluntary isometric hip abduction-, hip extension, and knee extension strength (Nm/kg) measured using a handheld dynamometer, and functional capacity tests (30 second chair-stand test and a stair-climb test) was conducted as secondary outcomes. Results Sixteen women with a median (IQR) age of 51 (46–60) years were included. Median (IQR) Body Mass Index was 26.69 (23.59–30.46) kg/m2. Adherence to the total number of training sessions and the LL-BFR was 96.4 and 94.4%, respectively. Two patients dropped out due to (i) illness before initiation of LL-BFR and (ii) pain in the affected leg related to the LL-BFR-exercise. At follow-up both pain levels and patient-reported outcome measures improved. Isometric hip abduction-, hip extension-, and knee extension strength on both legs and functional performance increased. Conclusion: LL-BFR-exercise seems feasible for treatment of GT. At follow-up, a high adherence and low drop-out rate were observed. Further, patients reported clinically relevant reductions in pain, and showed significant increases in isometric hip and knee strength.
... This increases muscle protein uptake, protein synthesis, and stimulates myoblast and satellite cell proliferation (Florini et al., 1996). Abe's study found that after even 2 weeks of BFR training at 20%1RM, circulating IGF-1 was 23.8% higher than baseline, whereas the non-BFR matched intensity group saw no significant change (Abe et al., 2005). IGF-1 activates mammalian target of Rapamycin (mTOR), resulting in a mechanism that causes cell division and tissue growth (Feng and Levine, 2010). ...
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Background Blood flow restriction (BFR) training at lower exercise intensities has a range of applications, allowing subjects to achieve strength and hypertrophy gains matching those training at high intensity. However, there is no clear consensus on the percentage of limb occlusion pressure [%LOP, expressed as a % of the pressure required to occlude systolic blood pressure (SBP)] and percentage of one repetition max weight (%1RM) required to achieve these results. This review aims to explore what the optimal and minimal combination of LOP and 1RM is for significant results using BFR. Method A literature search using PubMed, Scopus, Wiley Online, Springer Link, and relevant citations from review papers was performed, and articles assessed for suitability. Original studies using BFR with a resistance training exercise intervention, who chose a set %LOP and %1RM and compared to a non-BFR control were included in this review. Result Twenty-one studies met the inclusion criteria. %LOP ranged from 40 to 150%. %1RM used ranged from 15 to 80%. Training at 1RM ≤20%, or ≥ 80% did not produce significant strength results compared to controls. Applying %LOP of ≤50% and ≥ 80% did not produce significant strength improvement compared to controls. This may be due to a mechanism mediated by lactate accumulation, which is facilitated by increased training volume and a moderate exercise intensity. Conclusion Training at a minimum of 30 %1RM with BFR is required for strength gains matching non-BFR high intensity training. Moderate intensity training (40–60%1RM) with BFR may produce results exceeding non-BFR high intensity however the literature is sparse. A %LOP of 50–80% is optimal for BFR training.
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Background Muscle atrophy is common after an injury to the knee and anterior cruciate ligament reconstruction (ACLR). Blood flow restriction therapy (BFR) combined with low-load resistance exercise may help mitigate muscle loss and improve the overall condition of the lower extremity (LE). Purpose To determine whether BFR decreases the loss of LE lean mass (LM), bone mass, and bone mineral density (BMD) while improving function compared with standard rehabilitation after ACLR. Study Design Randomized controlled clinical trial Methods A total of 32 patients undergoing ACLR with bone-patellar tendon-bone autograft were randomized into 2 groups (CONTROL: N = 15 [male = 7, female = 8; age = 24.1 ± 7.2 years; body mass index [BMI] = 26.9 ± 5.3 kg/m2] and BFR: N = 17 [male = 12, female = 5; age = 28.1 ± 7.4 years; BMI = 25.2 ± 2.8 kg/m2]) and performed 12 weeks of postsurgery rehabilitation with an average follow-up of 2.3 ± 1.0 years. Both groups performed the same rehabilitation protocol. During select exercises, the BFR group exercised under 80% arterial occlusion of the postoperative limb (Delfi tourniquet system). BMD, bone mass, and LM were measured using DEXA (iDXA, GE) at presurgery, week 6, and week 12 of rehabilitation. Functional measures were recorded at week 8 and week 12. Return to sport (RTS) was defined as the timepoint at which ACLR-specific objective functional testing was passed at physical therapy. A group-by-time analysis of covariance followed by a Tukey’s post hoc test were used to detect within- and between-group changes. Type I error; α = 0.05. Results Compared with presurgery, only the CONTROL group experienced decreases in LE-LM at week 6 (−0.61 ± 0.19 kg, −6.64 ± 1.86%; P < 0.01) and week 12 (−0.39 ± 0.15 kg, −4.67 ± 1.58%; P = 0.01) of rehabilitation. LE bone mass was decreased only in the CONTROL group at week 6 (−12.87 ± 3.02 g, −2.11 ± 0.47%; P < 0.01) and week 12 (−16.95 ± 4.32 g,−2.58 ± 0.64%; P < 0.01). Overall, loss of site-specific BMD was greater in the CONTROL group ( P < 0.05). Only the CONTROL group experienced reductions in proximal tibia (−8.00 ± 1.10%; P < 0.01) and proximal fibula (−15.0±2.50%, P < 0.01) at week 12 compared with presurgery measures. There were no complications. Functional measures were similar between groups. RTS time was reduced in the BFR group (6.4 ± 0.3 months) compared with the CONTROL group (8.3 ± 0.5 months; P = 0.01). Conclusion After ACLR, BFR may decrease muscle and bone loss for up to 12 weeks postoperatively and may improve time to RTS with functional outcomes comparable with those of standard rehabilitation.
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Blood flow restriction (BFR) during low‐intensity exercise has been known to be a potent procedure to alter metabolic and oxygen environments in working muscles. Moreover, the use of BFR during inter‐set rest periods of repeated sprint exercise has been recently suggested to be a potent procedure for improving training adaptations. The present study was designed to determine the effect of repeated sprint exercise with post‐exercise BFR (BFR during rest periods between sprints) on muscle oxygenation in working muscles. Eleven healthy males performed two different conditions on different days: either repeated sprint exercise with BFR during rest periods between sets (BFR condition) or without BFR (CON condition). A repeated sprint exercise consisted of three sets of 3 × 6‐s maximal sprints (pedaling) with 24s rest periods between sprints and 5 min rest periods between sets. In BFR condition, two min of BFR (100–120 mmHg) for both legs was conducted between sets. During the exercise, power output and arterial oxygen saturation (SpO2) were evaluated. Muscle oxygenation for the vastus lateralis muscle, exercise‐induced changes in muscle blood flow, and muscle oxygen consumption were measured. During BFR between sets, BFR condition presented significantly higher deoxygenated hemoglobin + myoglobin (p < 0.01) and lower tissue saturation index (p < 0.01) than those in CON condition. However, exercise‐induced blood lactate elevation and reduction of blood pH did not differ significantly between the conditions. Furthermore, power output throughout nine sprints did not differ significantly between the two conditions. In conclusion, repeated sprint exercise with post‐exercise BFR augmented muscle deoxygenation and local hypoxia, without interfering power output.
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This study aimed to evaluate the local temperature, lactate, and blood glucose in three strength training methods. The study included 12 male subjects; (22.15 ± 5.77 years, 76.85 ± 9.15 kg, 1.72 ± 0.09 m), with minimum of 12 months of strength training experience, and all participated in the three training methods: the occlusion training (Kaatsu); the tension training (Tension); and the traditional training (Traditional). The Kaatsu training consisted in 3 sets of 10RM with occlusion device in both arms inflated to a 130% occlusion pressure. In addition, the tension method was performed with 30% of 1RM and the traditional training, consisted in 10 repetitions with 80% RM. Regarding the temperature variation, differences were observed between the Kaatsu and Traditional methods in relation to Tension (p = .049, η 2 p = 0.187). While for blood glucose (p = .351, η 2 p = 0.075) and lactate (p = .722, η 2 p = 0.022) there were no differences between the methods. Regarding the temperature (°C) measured by thermography and asymmetry, the right side showed a decrease in the post-test, in relation to the pre-test, in all methods (p < .05, η 2 p > 0.150). The left (p = .035, η 2 p = 0.301) and right (p = .012, η 2 p = 0.324) sides showed a decrease in temperature, in the post-test in relation to the pre-test, in the Kaatsu and traditional method. In asymmetry, the three methods showed an increase in the post-test in relation to the pre-test (p = .042, η 2 p = 0.158). In conclusion, tension method seems to stimulate greater heat production than the other methods. This information can help coaches to choose among these training methods according to the desired physiological response.
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Objective To systematically evaluate the effect of blood flow restriction (BFR) combined with low-intensity (LI) training on muscular strength and function of older adults. Methods Databases including PubMed, Web of Science, EBSCO host, Cochrane Library, CNKI, Wan Fang Data were searched to collect randomized controlled trials (RTCs) investigating the effects of BFR-LI training on muscular strength and function of older adults. The Cochrane bias risk assessment tool was applied to evaluate the methodological quality of the included studies, and acquired data were statistically analyzed using Stata 14.0 software. The retrieval period is from the establishment of the database to February 2022. Results Eighteen RCTs were included, with a total sample size of 419 people. Meta-analysis shows that BFR-LI training significantly improves the lower limb muscle strength (SMD: 0.66, 95%CI: [0.41,0.91], p < 0.001), and muscle function in Timed Up and Go Test (SMD: 0.79, 95%CI: [0.07,1.51], p < 0.05), and 30 Second Sit to Stand Test (SMD: 0.77, 95%CI: [0.13–1.40], p < 0.05). Different condition of control group (β = 0.48, 95% CI: [−0.98,-0.50], p < 0.01) and exercise duration (β = 1.05, 95% CI:[0.00,0.09], p < 0.05) were significant moderators in subgroup and meta-regression analyses. The effects of BFR-LI on strength gain are greater than regular LI-training in combined with resistance training and walking training, but weaker than the effect of high-intensity (HI) training. Conclusion BFR-LI training can effectively improve the muscular strength and function of the lower limbs of older adults. However, due to the limitations in the quality of the included research (inappropriate research design, small sample size, etc.), issues such as pressure intensity and exercise risk still need to be confirmed by more standardized and high-quality studies.
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The purpose of this study was to compare the aspects of the isokinetic muscle strength change of the resistance training with blood flow restriction(30%/1RM) and high(80%/1RM) or low(30%/1RM) load resistance training. 21 young men were selected as subjects and assigned to the resistance training with blood flow restriction group(n=7, BLRT), high load resistance training group(n=7, HRT), and low load resistance training group(n=7, LRT). The cuff pressure of both lateral femurs of BLRT was set at 100-110mmHg. The exercise of each group was performed three times per week. The isokinetic muscle strength tests of all subjects for analyzing isokinetic muscle strength of 60deg/sec, 180deg/sec and 240deg/sec were measured every 3 weeks during 12 weeks of exercise. A two-way ANOVA(with repeated measures) and one-way ANOVA(with repeated measures) were used to compare the isokinetic muscle strength of 3 groups. There were no significant differences in the time×group and group variables. However, there was a significant improvement of isokinetic muscle strength in HRT, while there was no significant improvement of isokinetic muscle strength in BLRT and LRT. Unlike the HRT, BLRT and LRT showed no difference in isokinetic muscle strength. It is necessary to reconsider the application of BLRT and blood flow restriction. Key words : resistance training with blood flow restriction, isokinetic muscle strength
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The purpose of this investigation was to determine the long-term training adaptations associated with low-volume circuit-type versus periodized high-volume resistance training programs in women. 34 healthy, untrained women were randomly placed into one of the following groups: low-volume, single-set circuit (SSC; N = 12); periodized high-volume multiple-set (MS; N = 12); or nonexercising control (CON) group (N = 10). The SSC group performed one set of 8-12 repetitions to muscular failure 3 d x wk(-1). The MS group performed two to four sets of 3-15 repetitions with periodized volume and intensity 4 d x wk(-1). Muscular strength, power, speed, endurance, anthropometry, and resting hormonal concentrations were determined pretraining (T1), after 12 wk (T2), and after 24 wk of training (T3). 1-RM bench press and leg press, and upper and lower body local muscular endurance increased significantly (P < or = 0.05) at T2 for both groups, but only MS showed a significant increase at T3. Muscular power and speed increased significantly at T2 and T3 only for MS. Increases in testosterone were observed for both groups at T2 but only MS showed a significant increase at T3. Cortisol decreased from T1 to T2 and from T2 to T3 in MS. Insulin-like growth factor-1 increased significantly at T3 for SSC and at T2 and T3 for MS. No changes were observed for growth hormone in any of the training groups. Significant improvements in muscular performance may be attained with either a low-volume single-set program or a high-volume, periodized multiple-set program during the first 12 wk of training in untrained women. However, dramatically different training adaptations are associated with specific domains of training program design which contrast in speed of movement, exercise choices and use of variation (periodization) in the intensity and volume of exercise.
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A total of 117 Japanese subjects (62 men and 55 women) volunteered for the study. Subcutaneous adipose tissue (AT) and muscle thicknesses were measured by B-mode ultrasonography at nine sites of the body. Body density (BD) was determined the hydrodensitometry. Reproducibility of thickness measurements by ultrasonography was high (r = 0.96–0.99). Correlations between AT thickness and BD ranged from −0.46 (gastrocnemius) to −0.87 (abdomen) for males and −0.46 (gastrocnemius) to −0.84 (abdomen) for females. A higher negative correlation (r = −0.89) was observed for the sum of AT thicknesses (forearm, biceps, triceps, abdomen, subscapula, quadriceps, hamstrings, gastrocnemius, and tibialis anterior) both in males and in females. Slightly lower coefficients were observed between muscle thickness and LBM (r = 0.36 to r = 0.70 for males and r = 0.44 to r = 0.55 for females). Prediction equations for BD and LBM from AT and muscle thickness were obtained by multiple regression analysis. Cross-validation on a separate sample (33 men and 44 women) showed an accurate prediction for BD. The present findings suggest that B-mode ultrasonography can be applied in clinical assessment and field surveys. © 1994 Wiley-Liss, Inc.
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Quadriceps muscle and fibre cross-sectional areas (CSA), torque and neural activation were studied in seven healthy males during 6 months of weight training on alternate days with six series of eight unilateral leg extensions at 80% of one repetition maximum. After training, the quadriceps cross-sectional area increased by 18.8 +/- 7.2% (P < 0.001) and 19.3 +/- 6.7% (P < 0.001) in the distal and proximal regions respectively, and by 13.0 +/- 7.2% (P < 0.001) in the central region of the muscle. Hypertrophy was significantly different between and within the four constituents of the quadriceps. Biopsies of the vastus lateralis at mid-thigh did not show any increase in mean fibre cross-sectional area. Maximum isometric voluntary torque increased by 29.6 +/- 7.9%-21.1 +/- 8.6% (P < 0.01-0.05) between 100 degrees and 160 degrees of knee extension, but no change in the optimum angle (110 degrees-120 degrees) for torque generation was found. A 12.0 +/- 10.8% (P < 0.02) increase in torque per unit area together with a right shift in the IEMG-torque relation and no change in maximum IEMG were observed. Time to peak isometric torque decreased by 45.8% (P < 0.03) but no change in time to maximum IEMG was observed. In conclusion, strength training of the quadriceps results in a variable hypertrophy of its components without affecting its angle-torque relation. The increase in torque per unit area, in the absence of changes in IEMG, may indicate changes in muscle architecture. An increase in muscle-tendon stiffness may account for the decrease in time to peak torque.
Article
The transforming growth factor-beta (TGF-beta) superfamily encompasses a large group of growth and differentiation factors playing important roles in regulating embryonic development and in maintaining tissue homeostasis in adult animals. Using degenerate polymerase chain reaction, we have identified a new murine TGF-beta family member, growth/differentiation factor-8 (GDF-8), which is expressed specifically in developing and adult skeletal muscle. During early stages of embryogenesis, GDF-8 expression is restricted to the myotome compartment of developing somites. At later stages and in adult animals, GDF-8 is expressed in many different muscles throughout the body. To determine the biological function of GDF-8, we disrupted the GDF-8 gene by gene targeting in mice. GDF-8 null animals are significantly larger than wild-type animals and show a large and widespread increase in skeletal muscle mass. Individual muscles of mutant animals weigh 2-3 times more than those of wild-type animals, and the increase in mass appears to result from a combination of muscle cell hyperplasia and hypertrophy. These results suggest that GDF-8 functions specifically as a negative regulator of skeletal muscle growth.
Article
The purpose of this study was to investigate the time course of skeletal muscle adaptations resulting from high-intensity, upper and lower body dynamic resistance training (WT). A group of 17 men and 20 women were recruited for WT, and 6 men and 7 women served as a control group. The WT group performed six dynamic resistance exercises to fatigue using 8-12 repetition maximum (RM). The subjects trained 3 days a week for 12 weeks. One-RM knee extension (KE) and chest press (CP) exercises were measured at baseline and at weeks 2, 4, 6, 8, and 12 for the WT group. Muscle thickness (MTH) was measured by ultrasound at eight anatomical sites. One-RM CP and KE strength had increased significantly at week 4 for the female WT group. For the men in the WT group, 1 RM had increased significantly at week 2 for KE and at week 6 for CP. The mean relative increases in KE and CP strength were 19% and 19% for the men and 19% and 27% for the women, respectively, after 12 weeks of WT. Resistance training elicited a significant increase in MTH of the chest and triceps muscles at week 6 in both sexes. There were non-significant trends for increases in quadriceps MTH for the WT groups. The relative increases in upper and lower body MTH were 12%-21% and 7%-9% in the men and 10%-31% and 7%-8% in the women respectively, after 12 weeks of WT. These results would suggest that increases in MTH in the upper body are greater and occur earlier compared to the lower extremity, during the first 12 weeks of a total body WT programme. The time-course and proportions of the increase in strength and MTH were similar for both the men and the women.