Light Weights, Low Oxygen: Hypoxia & Vascular Occlusion Training Yield Similar Increases in Neuromuscular Activation & Maximal Voluntary Force Generation in Female Athletes

The left part of the image shows what scientifically proven hypoxic training looks like. You wear a mask with an exogenous supply of low oxygen air. The right part of the image shows you what the fitness industry will try to sell you as "hypoxic training". That being said, did you know that at least the left version could also help you shed 11%% of your body fat in three weeks (learn more)?
Based on the feedback I got on the mini-summary of the latest review on "Kaatsu" aka blood flow restricted training I posted as part of last Monday's Exercise Science Round Up, I gather that many of you will be interested to hear about the results of a pertinent experiment that has been conducted only recently at the Lincoln University in Christchurch; New Zealand (Manimmanakorn. 2013).

To elicit, whether a combination of resistance training and vascular occlusion would modify the patterns of muscle activation, the development of muscle strength and hypertrophy, and whether these effects could be replicated by training under hypoxic conditions, the scientists who were involved in this research recruited 30 female netballers (age 20.2 ± 3.3 years, height 168.4 ± 5.8 cm; body mass 65.2 ± 6.5 kg, mean ± SD).

Ladies, hold your breath ;-)

The women were in their pre-competition training phase, and matched on their netball ability (had equal training volume, and were trained by the same physical conditioner). They were randomly assigned to either hypoxic training (HT), vascular occlusion (=Kaatsu; KT) and control training (CT) and had them perform bilateral knee extensions and flexions from 0 to 90° on a regular leg extension machine.The detailed experimental protocol for the three groups looked like this:
If you don't intend to suffocate yourself or at least your leg muscles, but still have (for whatever reason) to use lighter weights, you may be interested in another recent study, which was able to show that ballistics lunges activate muscles to the same extent as 34% lighter standardlifts and that this effect can be improved by using elastic band & dumbbells (learn more)
"During each set of knee extensions and flexions, participants in the HT group received normobaric hypoxic gas from a face mask via a hypoxicator system . The fraction of inspired oxygen (FIO2) was automatically adjusted by the hypoxicator using a biofeedback control system to maintain saturation of peripheral oxygen (SpO2) at *80 % (normal SpO2, approximately 99 %). The KT group performed training with restricted leg vascular blood flow in both lower limbs. During training, the pressure exerted by the Kaatsu cuffs (which were approximately 5 cm in width) at the root of the thigh,was gradually increased by 10 mmHg each day, starting from 160 mmHg at Day 1 going up to 230 mmHg at Day 8. The pressure then remained unchanged throughout the remaining of the training (Abe 2006). Heart rate and SpO2 were monitored by a pulse oximeter at the end of each exercise set. The CT group performed knee extension and flexion exercises with the Kaatsu cuffs on but not inflated (<5 mmHg) and breathed normal ambient room air." (my markups in Manimmanakorn. 2013)
In the course of the 5-week training period the participants completed three training sessions per week. Each training session consisted of three sets of knee extensions followed by three sets of knee flexions to failure (unable to complete the exercise successfully). The total number of sets was thus six, with 30s rest between sets and 2-min rest between exercises and a TUT (time under tension) of 1 0 1, which means that the women performed the exercise with a 1s concentric, 0 seconds rest at the top and a 1s eccentric contraction.

"Building strength with 20% of the 1-RM? You are kiddin' me, right?"

The resistance used was light - very light in fact: 20 % of the 1-RM. And as if that was not already light enough, the HT and CT groups of which the scientists expected that they would be able to perform more reps were advised to match the repetitions performed by the KT group "to ensure equal training load between groups" (during the tests the subjects were obviously required to perform as many reps as they could). Against that background, it's actually not surprising that there were no increases in any of the measured parameters in the control group:
Figure 1: Relative changes (in %) in the peak maximum voluntary contraction in 3 s,  area under the 30 s MVC curve,the number of repetitions able to be performed at 20 % 1-RM (left) and changes in surface electromyogram (EMG) amplitude (root mean square RMS %) during the Reps20 test before (pre) and after (post) 5 weeks training (Manimmanakorn. 2013)
As you can see in figure 1 the hypoxia training turned out to be the most effective if training methods - at least, if we go by the absolute increases in maximal voluntary contraction. The difference to the Kaatsu condition, however was trivial for all three parameters: The MVC3, the MVC30 and the total number of reps at 20% of the 1-RM.

The gym of the future a torture chamber or just an "old-school" gym in the basement?

Whether the gyms of the future will hand out cuffs at the door or "simply" have a low oxygen environment... wait a second: Now I know why all the strong guys train in these non-air-conditioned old-school gyms. It's to create a hypoxic environment, one of which the researchers say that it furthers "substantial increases in strength and endurance", which were "undoubtedly" brought about in part due to increased skeletal muscle hypertrophy.
Takarada et al. found that low inten- sity occlusion training can induce greater increases biceps CSA than regular high intensity training even in trained subjects (Takarada. 2000)
"However, indications of specific neuromuscular adaptation were also detected in the form of an increased EMG signal during the MVCs, particularly in the vascular occlusion group, indicating that increased motor unit activation probably also played a role in enhanced force production in these participants. Additionally, during a dynamic fatiguing exercise (Reps20) improvement in performance by the hypoxic and vascular occlusion groups post-training was in part due to improved efficiency of the force production machinery of the muscle." (Manimmanakorn. 2013)
Unfortunately, the actual increases in muscle cross sectional area (CSA) were not measured in the study at hand, but based on the findings of previous studies, which did report (in some cases) pretty impressive increases in CSA (see image next to the citation for one impressive example), I guess the scientists assumption that the ladies in the hypoxia and Kaatsu groups will also have gained more muscle than their peers is more than plausible.

Looking for readily available intensity techniques? "Unleash the Neanderthal Within" with Adelfo Cerame's "Fav Five Intensity Techniques" (learn more)
Bottom line: Now, let's get back to the "gym of the future" - I am not yet convince that we are soon going to see the air being sucked out of the gyms, but I am more and more convinced that blood flow restriction, Kaatsu, vascular occlusion or whatever else you may be using to reduce the oxygen supply to the muscle and thus increase the amount of eu-stress (=beneficial stress, learn more), will probably become the "intensity technique" of the future - if not on a "whole gym level", then maybe in form of one or two of those neat cages (see image at the bottom of the article).

Whatever the future may hold, I still feel that it is very unlikely that Katsuu and hypoxic training with light weights are ever going to replace "regular" strength training completely. 

After all, working out should be more to you than just a means to develop sleeve bursting biceps. Honestly, if you seriously can say for yourself that you would not miss lifting heavy weights and would willingly content yourself with the knowledge that you should be able to do that, it's no wonder that you are clutching to any straw to finally make those gains you have been chasing for years.

Kaatsu training on methodological dope: Where is the level playing ground?"

You should also keep in mind that neither the study at hand, nor the previously mentioned and unquestionable impressive study by Takarada offered a level playing ground for the contestants, i.e. classic hypertrophy vs. Kaatsu or training in hypoxic conditions.

Is this how the gym of the future looks like? I guess, the results of the study at hand are still not enough to predict the future, but when I was looking for a nice video to go with this article, I found an ABC report that underlines that Victor Conte (yep, the "Balco guy") believes in the success of hypoxic training (watch video)
The "high intensity" condition in the Takarada condition prescribed training loads from 50-80% and would be considered "moderate" by the majority of muscle heads. Manimmanakorn study, on the other hand, the fact that the "HT and CT groups were then instructed to match the repetitions performed by the KT group to ensure equal training load between groups" (Manimmanakorn. 2013) is a major downside to its real world significance and makes me wonder what the ladies in the HT group could have achieved, when they would not have had to stop "before their time"...

... ah, and I don't have to mention that not having a high intensity group in the Manimmanakorn study reminds me of those sponsored pre-workout supplement studies, here the placebo is either plain water or simple sugar - when you want to prove something is superior to common practice you better test it against common practice or your data is of highly questionable practical value. 

  • Abe T, Kearns CF, Sato Y (2006) Muscle size and strength are increased following walk training with restricted venous blood flow from the leg muscle, Kaatsu-walk training. J Appl Physiol 100:1460–1466 
  • Manimmanakorn A, Manimmanakorn N, Taylor R, Draper N, Billaut F, Shearman JP, Hamlin MJ. Effects of resistance training combined with vascular occlusion or hypoxia on neuromuscular function in athletes. Eur J Appl Physiol. 2013 Feb 15.
  • Takarada Y, Takazawa H, Sato Y, Takebayashi S, Tanaka Y, Ishii N. Effects of resistance exercise combined with moderate vascular occlusion on muscular function in humans. J Appl Physiol. 2000 Jun;88(6):2097-106. 
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