Takashi Abe, Charles F. Kearns, and Yoshiaki Sato. Muscle size and strength are increased following walk training with restricted venous blood flow from the leg muscle, Kaatsu-walk training. Appl Physiol. 2006 May;100(5):1460-6.

ABSTRACT

Previous studies have shown that low-intensity resistance training with restricted muscular venous blood flow (Kaatsu) causes muscle hypertrophy and strength gain. To investigate the effects of daily physical activity combined with Kaatsu, we examined the acute and chronic effects of walk training with and without Kaatsu on MRI-measured muscle size and maximum dynamic (one repetition maximum) and isometric strength, along with blood hormonal parameters. Nine men performed Kaatsu-walk training, and nine men performed walk training alone (control-walk). Training was conducted two times a day, 6 days/wk, for 3 wk using five sets of 2-min bouts (treadmill speed at 50 m/min), with a 1-min rest between bouts. Mean oxygen uptake during Kaatsu-walk and control-walk exercise was 19.5 (SD 3.6) and 17.2 % (SD 3.1) of treadmill-determined maximum oxygen uptake, respectively. Serum growth hormone was elevated (P < 0.01) after acute Kaatsu-walk exercise but not in control-walk exercise. MRI-measured thigh muscle cross-sectional area and muscle volume increased by 4–7%, and one repetition maximum and maximum isometric strength increased by 8–10% in the Kaatsu-walk group. There was no change in muscle size and dynamic and isometric strength in the control-walk group. Indicators of muscle damage (creatine kinase and myoglobin) and resting anabolic hormones did not change in both groups. The results suggest that the combination of leg muscle blood flow restriction with slow-walk training induces muscle hypertrophy and strength gain, despite the minimal level of exercise intensity. Kaatsu-walk training may be a potentially useful method for promoting muscle hypertrophy, covering a wide range of the population, including the frail and elderly.

In this study researchers fitted their test subjects with a belt that restricted the blood supply to the legs, and then set them to walk on a treadmill. The control group walked without having their blood supply restricted. Data showed that the production of growth hormone rose considerably during and after the session. The concentration of cortisol remained low. The treadmill training did lead to a dramatic growth in muscle tissue.

Now why is this study of any interest?

Have you seen Ronnie Coleman train? Noticed the tight restrictive clothing (powerlifting gear) he wears when he trains heavy days? Coleman wears a squat suit and deadlift suit on his heavy powerlifting days. This restricts blood flow to the muscles and causes the Kaatsu effect?

Ok, so what evidence do I have to support this idea?

Godawa TM, Credeur DP, Welsch MA. Influence of compressive gear on powerlifting performance: role of blood flow restriction training. J Strength Cond Res. 2012 May;26(5):1274-80.

ABSTRACT: This study investigated the effects of powerlifting gear on training volume and performance, defined by the squat, bench press, and deadlift. Eighteen powerlifters (18-26 years) were randomized into either a group that trained and competed using compressive gear (CG) or without the gear (NON). Training volume, volume progression, and powerlifting performance were assessed before and after 10 weeks of training. Training volume increased in the first 4 weeks for both groups. Volume lifted for squat and the totals were greater in the CG. There was an increase in squat (19.05 ± 30.97 lb, p = 0.02), deadlift (19.05 ± 21.17 lb, p = 0.001), and the total score (44.00 ± 60.44 lb, p = 0.005) for both the groups. The improvements in squat (CG = 33.85 vs. NON = 5.74, p = 0.07) and totals (CG = 66.59 vs. NON = 23.67, p = 0.15) were greater in the CG. Both groups showed a significant and similar increase in the Wilks scores (+13.54 points, p = 0.03). There was a trend toward greater volume progression in those wearing CG during the initial stages of training. Both the groups significantly improved performance for the squat, and deadlift, and had higher totals, and Wilks scores, indicating significant strength gains. The greater magnitude of improvements in the squat and totals for the CG lifters suggests an ergogenic potential of training with powerlifting gear.

In the above study researchers wanted to know whether the Kaatsu effect was the reason behind the gains in muscular strength and size powerlifters get who train and compete in restrictive powerlifting equipment. For year myself and other powerlifters have been saying our unequipped lifts get stronger and we are putting on lots of size by training in equipment all the time. Those who are against equipment deny these claims and just say the squat suits and bench shirts are doing all the work. Well, I have offered my for anyone who really believed such nonsense. Who my Inzer canvas squat can stand up on it's own I can se the 45 pound bar on it and it is crushed.

Anyway, the results of this study showed that those who trained in equipment trained with more weigh, with more volume and more reps. By the end of the 10 week study the equipped group had made dramatically more progress that the non-equipped group. Also foudn was a dramatic reduction in blood flow with the muscle groups that we being used in the testing and restricted by the equipment. This lead researchers to believe that the Kaatsu effect is definitely a part of the reason powerlifters who train in equipment grow more and get stronger that their no-equipped counter parts.

Further evidence:

Stephen D. Patterson and Richard. A. Ferguson. Increase in calf post-occlusive blood flow and strength following short-term resistance exercise training with blood flow restriction in young women. European Journal of Applied Physiology, 2010, Volume 108, Number 5, Pages 1025-1033.

Kon M, Ikeda T, Homma T, Akimoto T, Suzuki Y, Kawahara T. Effects of acute hypoxia on metabolic and hormonal responses to resistance exercise. Med Sci Sports Exerc. 2010 Jul;42(7):1279-85.

Researchers concluded that resistance exercise in hypoxic condition caused greater accumulation of metabolites and strong anabolic hormone response.

Satoshi Fujita, Takashi Abe, Micah J. Drummond, Jerson G. Cadenas, Hans C. Dreyer, Yoshiaki Sato, Elena Volpi, and Blake B. Rasmussen. Blood flow restriction during low-intensity resistance exercise increases S6K1 phosphorylation and muscle protein synthesis. Published online before print June 14, 2007.

This time, researchers concluded that the activation of the mTOR signaling pathway appears to be an important cellular mechanism that may help explain the enhanced muscle protein synthesis during Kaatsu.

Are you convinced yet. Could 100's of equipped powerlifters be right? Are bodybuilders like Ronnie Coleman setting the pathway for superhuman growth? Is powerlifting gear another tool you need in your training?

Not only will powerlifiting gear help you lift more, train harder and grow bigger, it also has been found to take the shear stress of the joints involved in the lift like this shoulder, thus keeping you in the game longer and injury free.

My wife has always been one of those who thought I was nuts for doing my core lifts with equipment on. She did not believe that the equipment was not doing all the work and my muscle were getting nothing. Yet each time I walk out of the gym the muscle I train are totally exhausted and sore as shit the next day. I am constantly able to add 5-10 lbs on my best reps each week despite being 55 years old. My muscle growth continues. The only times I have really gotten injured in my over 30 years of pushing heavy weight was when I trained without equipment.