8/12/2019 Blood Flow Restriction Resistance Training Potential Benefits of Choking the Muscles

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Research Digest

The Research Digest Column summarizes a keyresearch article in the field of strength and conditioningand provides practical applications for the strength andconditioning practitioner.

COLUMN EDITOR: Perry Koziris, PhD, CSCS*D,NSCA-CPT*D, FNSCA

Blood Flow Restriction

Resistance Training:Potential Benefits ofChoking the MusclesLymperis (Perry) Koziris, PhD, CSCS*D, NSCA-CPT*D, FNSCAInstitut National du Sport du Quebec, Montreal, Quebec, Canada

A B S T R A C TBLOOD FLOW RESTRICTION CAN

BE USED IN RESISTANCE EXER-

CISE TO AUGMENT PHYSIOLOGI-

CAL CHALLENGES AND

STIMULATE ADAPTATIONS WHEN

HEAVY LOADS ARE CONTRAINDI-

CATED. FEMALE ATHLETES USING

ONLY 20% 1 REPETITION MAXI-

MUM SUBSTANTIALLY IMPROVED

THEIR MUSCULAR ENDURANCE,

STRENGTH, HYPERTROPHY, AND

MOTONEURON RECRUITMENTEFFICIENCY, WHEN TRAINING

WAS COUPLED WITH LOCAL

OCCLUSION OR EVEN WITH

BREATHING HYPOXIC AIR.

Interest is rising in various ap-proaches that increase local muscleischemia during resistance exercise

(1). This blood flow restriction (BFR)may be partial or may involve completeocclusion. The more common methodsinclude the application of external devices

such as elastic straps or bands, or inflat-able cuffs, to reduce muscle blood flowduring lower-load resistance exercise;one systematic version of BFR trainingwith a specific cuff apparatus is known asKaatsu. Other possible methods includethe use of slower movements with lowerloads than those of typical heavy resis-tance training and without pausebetween repetitions nor between pha-ses (concentric or eccentric). Thishelps maintain an elevated intramus-cular pressure, thereby interfering

with local blood flow.BFR is appealing for situations wherethere is a desire to avoid heavy loadswhile creating a high degree of meta-bolic challenge in the muscle. Thismay stimulate adaptations in strengthand particularly in muscle hypertrophy,and the hypoxia resulting from BFR isone of the physiological mechanismsbeing considered (2). A recent studyexamined the role of this reduced oxygenavailability during low-load resistanceexercise in female athletes (3).

Two methods were used to create a hyp-oxic condition in the leg muscles whileresistance training with a low load; onewas the breathing of a low-oxygen gasmixture (HT) and the other was thighblood flow occlusion using Kaatsu cuffs(KT). Female netballers were assigned toone of 3 groups, HT, KT, and controltraining (CT), all involving a 5-weekstandardized program of 3 sessions perweek. The participants performed train-ing sessions consisting of 3 sets of kneeextension followed, after a 2-minute rest

period, by 3 of knee flexion, all witha resistance of 20% 1 repetition maxi-mum (RM). Repetitions lasted approxi-mately 1 second per phase, and the restintervals between sets lasted 30 seconds.All sets were taken to failure by the KTgroup and the other 2 groups were askedto match that number of repetitions perset to control for training load. Thegroupsrespective intervention was main-tained throughout each 1213-minutetraining session. In the HT, the percent-age of oxygen in the inspired air was

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8/12/2019 Blood Flow Restriction Resistance Training Potential Benefits of Choking the Muscles

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automatically adjusted to maintain arte-rial oxygen saturation at 80%. In the KT,cuff pressure was progressed from 160mm Hg on the first training day to 230

mm Hg on the eighth training day andwas kept at 230 mm Hg for the remain-der of the training sessions.

Strength and muscular endurance testsfor leg extension, which were performedin a separate session under normal con-ditions without any intervention, showeda much higher benefit of the 2 experi-mental modes relative to the controlcondition. Similarly, training with vascu-lar occlusion (KT) and with systemichypoxia (HT), compared with trainingwith an unimpeded muscle oxygen bal-

ance, resulted in changes in voluntaryneural activation of the leg extensorsand substantial thigh muscle growth.

With regard to the strength and mus-cular endurance testing, CT resultedin an improvement in the maximalnumber of repetitions that could becompleted with a 20% 1RM load(Reps20) but both KT and HTshowed a larger improvement in thisvariable. KT and HT also showed sub-stantial increases in peak isometric

force (maximal voluntary contracting;MVC) and in 30-second isometricmuscular endurance, whereas CTshowed little change in these varia-bles. Any differences between KTand HT in these 3 performance vari-ables were essentially trivial. Evenwith the lower training load (20%1RM) in this study, the KT and HTadaptations were comparable to thoseexpected from BFR training withhigher loads (50% 1RM) or from tra-ditional heavy resistance training.

Total quadriceps electromyographyintensity was also calculated from themuscle electrical activity as an index ofmuscle recruitment during these

performance tests. During the MVC,it increased in all 3 groups but substan-tially more as a result of KT. Higherneural activation during maximalefforts indicates that at least some ofthe strength increase is based onaltered neuromuscular functioning,which may include increased motorunit recruitment and synchronization,as well as increased motor unit firingfrequency. Furthermore, electromyog-raphy intensity during the Reps20decreased more after KT and HT. This

lowered motoneuron activity duringthe performance of the same taskpost-training points to a training-induced augmentation in the efficiencyof force generation. This makes sensebecause the same absolute load wasused for this test before and after train-ing; the load became, in effect, lighterfor the athletes post-training becauseof their increased 1RM.

The cross-sectional area of the kneeflexors and extensors was calculated atthe mid-thigh level and was shown toincrease substantially in KT and HTcompared with CT. This apparent mus-cular hypertrophy was of a similarmagnitude shown by previous studiesexamining similar protocols. This isthe first study, though, showing suchan effect in young trained femaleathletes.

The findings of this study do not amountto a recommendation for these types ofprotocols in lieu of typical strength train-ing programs in an athletic population.

The higher the training status of athletes,the more likely they are to benefit insteadfrom resistance training that adheresmore closely to the specificity principle

in regard to the sports demands forstrength, this being particularly true forpower needs. However, the results of thisstudy do provide additional support forthe utilization of these protocols by thestrength and conditioning coach whoneeds to maximize the physiologicalstimulus and optimize adaptations, espe-cially through the maintenance of musclemass, during suboptimal circumstanceswhere higher loading is contraindicateddue to injury or other factors. This studyreinforces this rationale particularly for

female athletes.Conflicts of Interest and Source of Funding:The author reports no conflicts of interestand no source of funding.

Lymperis (Perry) Kozirisis an exer-cise physiologist at the Institut Nationaldu Sport du Quebec.

REFERENCES1. Alberti G, Cavaggioni L, Silvaggi N,

Caumo A, and Garufi M. Resistance

training with blood flow restriction using themodulation of the muscles contraction

velocity. Strength Cond J35: 4247,

2013.

2. LoennekeJP and Pujol TJ. The use ofocclusion

training to produce muscle hypertrophy.

Strength Cond J31: 7784, 2009.

3. Manimmanakorn A, Manimmanakorn N,

Taylor R, Draper N, Billaut F, Shearman JP,

and Hamlin MJ. Effect of resistance training

combined with vascular occlusion or

hypoxia on neuromuscular function in

athletes.Eur J Appl Physiol113:

17671774, 2013.

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