KAATSU training involves the restriction of blood flow to exercising muscle and is the culmination of nearly 40 years of experimentation with the singular purpose of increasing muscle mass. KAATSU Training consists of performing low-intensity resistance training while a relatively light and flexible cuff is placed on the proximal part of one's lower or upper limbs, which provides appropriate superficial pressure. KAATSU Training should not be confused with training under ischemic conditions which has previously been reported (Sundberg, 1994). KAATSU Training does not induce ischemia within skeletal muscle, but rather promotes a state of blood pooling in the capillaries within the limb musculature. Applied basic and clinical research conducted over the past 10 years has demonstrated that KAATSU Training not only improves muscle mass and strength in healthy volunteers, but also benefits patients with cardiovascular and orthopedic conditions.

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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.

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Growth hormone (GH) is secreted in a pulsatile fashion during exercise, which promotes skeletal muscle growth and muscle strength. We compared the effects of different types of short-term low-intensity resistance exercise (STLIRE) on the hemodynamic and GH responses of men aged 20 to 45 years. Eleven untrained men performed 30 repetitions for 2 to 4 sets (mean 61 ± 7 repetitions) until fatigue for bilateral leg extension-flexion exercise (20% of 1 RM -Proteus Multi Exercise Machine) under the conditions of reduced muscle blood flow by applied pressure at the proximal ends of both legs by a specially-designed belt (Kaatsu Training). In the controlled exercise condition, without Kaatsu (n=9), subjects again performed the same exercise protocol as described above. Finally, a group of 5 men performed 3 sets of 10 repetitions using the Power Rehabilitation machine. Hemodynamic parameters were measured by using the impedance cardiography. Serum concentrations of GH, noradrenaline (NOR), and lactate were also measured. STLIRE with Kaatsu significantly increased GH, compared to STLIRE without Kaatsu. Maximal heart rate (HR) and blood pressure (BP) in STLIRE with Kaatsu were higher when compared to the control condition, however, stroke volume (SV) was lower compared to the controlled condition due to a decreased venous return induced by Kaatsu training. Total peripheral resistance (TPR) did not change significantly. The increase in NOR and lactate in STLIRE with Kaatsu was also significantly higher than without Kaatsu. These results suggest that “Kaatsu” leg resistance exercise caused a significant exercise-induced GH response even in STLIRE, with a reduction of cardiac preload during exercise. The results of the study indicate that Kaatsu training may become a unique method for rehabilitation in patients with cardiac diseases or low physical fitness.

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The purpose of this study was to investigate the effects of short-term KAATSU-resistance training on skeletal muscle size and sprint/jump performance in college athletes. Fifteen male track and field college athletes were randomly divided into two groups: KAATSU (resistive exercise combined with blood flow restriction, n=9) and control (n=6) groups. The KAATSU group trained twice daily with squat and leg curl exercises (20% of 1-RM, 3 sets of 15 repetitions) for 8 consecutive days while both KAATSU and control groups participated in the regular sprint/jump training sessions. Maximal strength, muscle-bone CSA, mid-thigh muscle thickness (MTH), and sprint/jump performance were measured before and after the 8 days of training. The muscle-bone CSA increased 4.5% (p<0.01) in the KAATSU group but decreased 1% (p>0.05) in the control group. Quadriceps and hamstrings MTH increased (p<0.01) by 5.9% and 4.5%, respectively, in the KAATSU group but did not change in the control group. Leg press strength increased (9.6%, p<0.01) in the KAATSU group but not (4.8%, p>0.05) in the control group. Overall 30-m dash times improved (p<0.05) in the KAATSU-training group, with significant improvements (p<0.01) occurring during the initial acceleration phase (0-10m) but not in the other phases (10-20m and 20-30m). None of the jumping performances improved (p>0.05) for either the KAATSU or control groups. These data indicated that eight days of KAATSU-training improved sprint but not jump performance in collegiate male track and field athletes.

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The present study investigated whether circuit training with body weight alone (no external load) can cause muscular hypertrophy when combined with moderate venous occlusion (‘Kaatsu Training’). Healthy women (mean age, 32.7 ± 4.0 yr; n=22) were randomly assigned into the occlusive training group (OCC, n=11) and the normal training group (NOR, n=11). Both groups performed the same circuit-training regimen consisting of six, successive exercises for muscles in the upper and lower limbs and the trunk, at a frequency of 3 sessions/wk. Each session lasted for 5-10 min. In OCC group, proximal ends of the upper and lower limbs of both sides were moderately compressed by means of ‘KAATS Sportswear’, to restrict the venous blood flow during the exercises (preset pressure, 50-80 mmHg and 80-120 mmHg for upper and lower limbs, respectively). Cross-sectional area (CSA) of the thigh muscle was measured with spiral computer tomography. After an 8-wk period of training, the muscle CSA of both right and left limbs showed significant increases by ∼3% (P<0.05) in the OCC group, whereas there was no change for the NOR group. To propose a mechanism for these findings, the acute effects of the same exercise regimen combined with occlusion on plasma concentration of growth hormone (GH) were further investigated with male subjects (n=2). The circuit exercise with occlusion elicited a dramatic increase in plasma GH, whereas that without occlusion did not, although statistical analysis could not be made. The results indicate that circuit training with only body weight can cause hypertrophy in lower-limb muscles when combined with moderate venous occlusion, but the exact mechanism is not yet understood.

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Low-intensity Kaatsu resistance training performed by patients with moderate vascular occlusion is known to cause skeletal muscle hypertrophy over a short term. In our patients who used such training as a part of their rehabilitation, we have seen the same results, as well as a quenching analgesic effect. Herein, we report the effect of Kaatsu resistance training in a patient with patella tendinitis. The patient was a 17-year-old male who played basketball and came to us with intense pain at the lower edge of the patella in the right knee and was confirmed by an MRI image which showed a high intensity signal in the area of the patella tendon. Initially, we gave a dose of antiphlogistic analgetic, a steroid injection, and prescribed hospitalization for 1 month. Kaatsu resistance training was also recommended in an attempt to prevent muscle atrophy. The vascular occlusion point for the Kaatsu training cuff was the proximal end of the right limb, which had an occlusion pressure ranging from 160-180 mmHg. The exercise components that were used in combination with the Kaatsu training program were SLR, hip abduction, hip adduction, calf raise, toe raise, squat, crunch, back extension, and shooting. The exercise protocol was performed at about 30% of 1RM, with 3 sets of 15 repetitions, 5 to 6 times per week, for 3 weeks. T2 weighted MRI images (axial and sagittal) of the right patella tendon prior to beginning Kaatsu training showed high intensity signals, however, after 3 weeks of Kaatsu training, the signal intensity was reduced and the thigh circumference was increased by 7 mm and 2 mm for the right and left sides, respectively. Further, there was no evidence of muscle atrophy. The present patient was then treated with appropriate anti-inflammatory drugs and 1-month of hospitalization. During that time it was possible to completely relieve the inflammation and avoid muscle atrophy with Kaatsu training, and the patient quickly returned to playing basketball. In conclusion, this low-intensity resistance training was able to be performed without applying excessive load, which may have caused further damage, and we intend to use Kaatsu training with future patients to help them return as early as possible to full activities.

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The gold standard for assessing muscle size (cross-sectional area and volume) has been magnetic resonance imaging (MRI) and computerized tomography (CT), however, these processes are very expensive and generally require a medical facility, and in the case of CT, can involve exposure to high levels of radiation. The advent of B-mode ultrasound, in conjunction with simple anthropometric measures, such as circumference, can perhaps offer a quick, valid and reliable, and cost effective method to estimate muscle cross-sectional area (CSA) and track changes in muscle CSA following training. The purpose of this study was to document the reliability and accuracy of B-mode ultrasound in combination with anthropometry for assessing Kaatsu training induced changes in muscle-bone CSA. The data from thirty-three young men (mean age, 22.2 ± 5.1 yrs) in four different training groups were combined for the statistical analysis. All subjects were assessed prior to training and three days after the last training session. Anthropometric assessment of the right thigh circumference was taken at the mid point of the thigh (between the lateral condyle of the femur and greater trochanter), and midline anterior (QAT) and posterior (HAT) measures of subcutaneous adipose tissue thickness, at the same level as the circumference measures, was obtained with B-mode ultrasound. The muscle-bone CSA was estimated with the following equation: [π (r - (QAT + HAT) /2)² ; r=circumference / 2π]. Each subject also had their right thigh imaged, at the same point as the circumference measure, by MRI. The estimated muscle-bone CSA was on average, 21% higher than the MRI measured CSA prior to training but the two methods were significantly (p<0.01) correlated (r=0.81). The correlation between the changes in estimated and MRI measured CSA due to muscle hypertrophy following Kaatsu training was also high (r=0.86) and significant (p<0.01) and only differed on average by 1.8% between two methods. In conclusion, it appears that anthropometry in combination with ultrasound can provide a reliable, accurate, and cost effective alternative method for assessing muscle hypertrophy.

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