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Purpose: This study examined respiratory and circulatory responses during low-intensity resistance exercise using a KAATSU device, which results in moderate blood flow restriction, in both healthy male adults and male patients with cardiovascular disease.Methods: Healthy males (n = 10, 29.8 ± 7.0 years) and male patients in cardiac rehabilitation (n = 10, 76.9 ± 3.4 years) performed leg extensions (3 sets of 15 repetitions at low-intensity [20% of a 1-repetition maximum]) not using and using a KAATSU device. We measured expiratory gas and impedance cardiography before (baseline) and during exercise, as well as dyspnea and rate of perceived exertion (RPE) during knee extensor effort immediately after each set of repetitions.Results: The patients were older than the healthy participants. At baseline, although heart rates and ventilatory equivalents did not differ between groups, oxygen uptake, carbon dioxide output, and left cardiac work index (LCWi) were lower in patients than in healthy participants. There were no GROUP × KAATSU interactions in terms of respiratory and circulatory responses during low-intensity resistance exercise. Dyspnea and RPE increased with exercise set repetitions and the KAATSU device augmented the RPE in both groups.Conclusions: There were no patient-specific changes in respiratory and circulatory responses, dyspnea, and responses to knee extensor effort using the KAATSU device during low-intensity resistance exercise, despite patients being older than healthy participants and exhibiting a lower respiratory function and LCWi at baseline than them. These results suggest that low-intensity resistance exercise using a KAATSU device can be a safe and useful training method for cardiac rehabilitation.

We examined the safety and the effects of low-intensity resistance training (RT) with moderate blood flow restriction (KAATSU RT) on muscle strength and size in patients early after cardiac surgery. Cardiac patients (age 69.6 ± 12.6 years, n = 21, M = 18) were randomly assigned to the control (n = 10) and the KAATSU RT group (n = 11). All patients had received a standard aerobic cardiac rehabilitation program. The KAATSU RT group additionally executed low-intensity leg extension and leg press exercises with moderate blood flow restriction twice a week for 3 months. RT-intensity and volume were increased gradually. We evaluated the anterior mid-thigh thickness (MTH), skeletal muscle mass index (SMI), handgrip strength, knee extensor strength, and walking speed at baseline, 5–7 days after cardiac surgery, and after 3 months. A physician monitored the electrocardiogram, rate of perceived exertion, and the color of the lower limbs during KAATSU RT. Creatine phosphokinase (CPK) and D-dimer were measured at baseline and after 3 months. There were no side effects during KAATSU RT. CPK and D-dimer were normal after 3 months. MTH, SMI, walking speed, and knee extensor strength increased after 3 months with KAATSU RT compared with baseline. Relatively low vs. high physical functioning patients tended to increase physical function more after 3 months with KAATSU RT. Low-intensity KAATSU RT as an adjuvant to standard cardiac rehabilitation can safely increase skeletal muscle strength and size in cardiovascular surgery patients.

Malnutrition is associated with sarcopenia, cachexia, and prognosis. We investigated the usefulness of phase angle (PhA) as a marker of sarcopenia, cachexia, and malnutrition in 412 hospitalized patients with cardiovascular disease. We analyzed body composition with bioelectrical impedance analysis, and nutritional status such as controlling nutritional status (CONUT) score. Both skeletal muscle mass index (SMI) and PhA correlated with age, grip strength and knee extension strength (p &lt, 0.0001) in both sexes. The SMI value correlated with CONUT score, Hb, and Alb in males. Phase angle also correlated with CONUT score, Hb, and Alb in males, and more strongly associated with these nutritional aspects. In females, PhA was correlated with Hb and Alb (p &lt, 0.001). In both sexes, sarcopenia incidence was 31.6% and 32.4%, PhA cut-off in patients with sarcopenia was 4.55&deg, and 4.25&deg, and cachexia incidence was 11.5% and 14.1%, respectively. The PhA cut-off in males with cachexia was 4.15&deg, Multivariate regression analysis showed that grip strength and brain natriuretic peptide (BNP) were independent determinants of SMI, whereas grip strength, BNP, and Hb were independent determinants of PhA. Thus, PhA appears to be a useful marker for sarcopenia, malnutrition, and cachexia in hospitalized patients with cardiovascular disease.

Blood flow restriction (BFR) has the potential to augment muscle activation, which underlies strengthening and hypertrophic effects of exercise on skeletal muscle. We quantified the effects of BFR on muscle activation in the rectus femoris (RF), the vastus lateralis (VL), and the vastus medialis (VM) in concentric and eccentric contraction phases of low-intensity (10% and 20% of one repetition maximum) leg extension in seven cardiovascular patients who performed leg extension in four conditions: at 10% and 20% intensities with and without BFR. Each condition consisted of three sets of 30 trials with 30 s of rest between sets and 5 min of rest between conditions. Electromyographic activity (EMG) from RF, VL, and VM for 30 repetitions was divided into blocks of 10 trials and averaged for each block in each muscle. At 10% intensity, BFR increased EMG of all muscles across the three blocks in both concentric and eccentric contraction phases. At 20% intensity, EMG activity in response to BFR tended to not to increase further than what it was at 10% intensity. We concluded that very low 10% intensity exercise with BFR may maximize the benefits of BFR on muscle activation and minimize exercise burden on cardiovascular patients.