Taira Fukuda

Effects of low‐intensity, elastic band resistance exercise combined with blood flow restriction on muscle activation

We examined the effects of blood flow‐restricted, low‐intensity resistance exercise (termed kaatsu) using an elastic band for resistance on muscle activation. Nine men performed triceps extension and biceps flexion exercises (four sets respectively) using an elastic band for resistance with blood flow restriction (BFR) or CON (unrestricted blood flow). During a BFR session, subjects wore pressure cuffs inflated to 170–260 mmHg on the proximal region of both arms. Surface electromyography (EMG) was recorded from the triceps brachii and biceps brachii muscles, and mean integrated EMG (iEMG) was analyzed. Blood lactate concentration was obtained before (Pre) and immediately after two exercises (Post). During triceps extension and biceps flexion exercises, muscle activation increased progressively (P < 0.05) under BFR (46% and 69%, respectively) but not under CON (12% and 23%, respectively). Blood lactate concentration at Post was higher (P < 0.05) under BFR than under CON (3.6 and 2.1 mmol/L, respectively). Blood lactate concentration at Post was significantly correlated with increased iEMG in both triceps extension (r = 0.65, P < 0.01) and biceps flexion exercises (r = 0.52, P < 0.05). We conclude that kaatsu training using elastic bands for resistance enhances muscle activation and may be an effective method to promote muscle hypertrophy in older adults or patients with a low level of activity.

Muscle size and arterial stiffness after blood flow-restricted low-intensity resistance training in older adults

Previous studies have shown that blood flow‐restricted low‐intensity resistance training (BFR‐RT) causes muscle hypertrophy while maintaining arterial function in young adults. We examined the effects of BFR‐RT on muscle size and arterial stiffness in older adults. Healthy subjects (ages 61–84 years) were divided into BFR‐RT (n = 9) or non‐training control (CON; n = 10) groups. The BFR‐RT group performed 20% and 30%, respectively, of one‐repetition maximal (1‐RM) knee extension and leg press exercises, 2 days/wk for 12 weeks. The BFR‐RT group wore elastic cuffs (120–270 mmHg) on both legs during training. Magnetic resonance imaging‐measured muscle cross‐sectional area (CSA), 1‐RM strength, chair stand (CS) test, and cardio‐ankle vascular index testing (CAVI), an index of arterial stiffness, were measured before and 3–5 days after the final training session. Muscle CSA of the quadriceps (8.0%), adductors (6.5%), and gluteus maximus (4.4%), leg extension and leg press 1‐RM strength (26.1% and 33.4%), and CS performance (18.3%) improved (P < 0.05) in the BFR‐RT group, but not in the CON group. In CAVI testing, there were no changes in both two groups. In conclusion, BFR‐RT improves muscle CSA as well as maximal muscle strength, but does not negatively affect arterial stiffness or humeral coagulation factors in older adults.

Haemostatic and inflammatory responses to blood flow-restricted exercise in patients with ischaemic heart disease: a pilot study.

Low‐intensity resistance exercise can effectively induce muscle hypertrophy and increases in strength when combined with moderate blood flow restriction (BFR). As this type of exercise does not require lifting heavy weights, it might be a feasible method of cardiac rehabilitation, in which resistance exercise has been recommended to be included. Although previous studies with healthy subjects showed relative safety of BFR exercise, we cannot exclude the possibility of unfavourable effects in patients with cardiovascular disease. We therefore aimed to investigate haemostatic and inflammatory responses to BFR exercise in patients with ischaemic heart disease (IHD). Nine stable patients with IHD who were not taking anticoagulant drugs performed four sets of knee extension exercise at an intensity of 20% one‐repetition maximum (1RM) either with or without BFR. Blood samples were taken before, immediately after and 1 h after the exercise session and analysed for noradrenaline, D‐dimer, fibrinogen/fibrin degradation products (FDP) and high‐sensitive C‐reactive protein (hsCRP). Plasma noradrenaline concentration increased after the exercise, and the increase was significantly larger after the exercise with BFR than without BFR. On the other hand, increases in concentrations of plasma D‐dimer and serum hsCRP were independent of the condition. However, increases in D‐dimer and hsCRP were no longer observed after plasma volume correction, suggesting that hemoconcentration was responsible for these increases. Plasma FDP concentration did not change after the exercise. These results suggest that applying BFR during low‐intensity resistance exercise does not affect exercise‐induced haemostatic and inflammatory responses in stable IHD patients.

Cardiac rehabilitation decreases plasma pentraxin 3 in patients with cardiovascular diseases

Background: Inflammatory markers such as serum C-reactive protein (CRP), serum amyloid A (SAA), and plasma pentraxin 3 (PTX3), which belong to the pentraxin superfamily, increase due to various inflammatory diseases. Some studies demonstrated that serum CRP and SAA are predictors of cardiovascular diseases, and cardiac rehabilitation (CR) induces anti-inflammatory effects. In the present study, we investigated the effects of CR on pentraxins (serum CRP, SAA, and plasma PTX3) in patients with cardiovascular diseases. Methods: Fifty patients with cardiovascular diseases [61 ± 13 (mean ± SD) years old, male/female 44/6] participated. Each subject performed CR using aerobic bicycle exercise two or three times per week for 3–6 months. We measured resting serum high-sensitivity CRP (hsCRP), SAA, and plasma PTX3 before and 3 and 6 months after CR, and compared them with VO2peak determined using a standard increment cycle ergometer protocol, B-type natriuretic peptide (BNP), and other biochemical data such as HbA1c. Results: There was a significant positive correlation between hsCRP and SAA (r = 0.92, p < 0.001), but no relations between these parameters and PTX3. Plasma PTX3 significantly decreased time dependently during CR (at baseline 3.2 ± 2.0 ng/ml, at 3 months 2.3 ± 0.8 ng/ml, at 6 months 2.1 ± 0.7 ng/ml; all p < 0.05). Serum hsCRP tended to decrease, but not statistically significantly. At baseline, plasma PTX3 was negatively correlated with the percentage of the predicted values of VO2peak and positively correlated with BNP. CR significantly increased the percentage of the predicted values of VO2peak and decreased BNP. Conclusions: Plasma PTX3, an inflammatory marker, which was quite different from CRP and SAA, decreased during cardiac rehabilitation with an improvement of exercise capacity in patients with cardiovascular diseases.

Cardiac Rehabilitation Increases Exercise Capacity with a Reduction of Oxidative Stress

Background and Objectives Reactive oxygen species (ROS) mediate various signaling pathways that underlie vascular inflammation in atherogenesis and cardiovascular diseases. Cardiac rehabilitation (CR) has a variety of multiple beneficial effects, including anti-inflammatory effects. The purpose of the present study was to investigate the effects of CR on ROS in patients with cardiovascular diseases. Subjects and Methods The serum level of derivatives of reactive oxidative metabolites, an index of oxidative stress, was measured in 100 patients with cardiovascular diseases before, and, subsequently, 3 and 6 months after, CR. A biological antioxidant potential (BAP) test was applied to assess the antioxidant power of the serum. Results The resting reactive oxidative metabolite levels decreased 3-6 months after CR {pre: 351±97 Carratelli unit (CARR U), 3 months: 329±77 CARR U, 6 months: 325±63 CARR U, all p<0.01} with the increase of the percentage of the predicted values of V̇O2 peak and the percentage of the predicted values of V̇O2 at the anaerobic threshold (V̇O2 AT) and the decrease of the B-type natriuretic peptide (BNP). The BAP test and antioxidative/oxidative stress ratio increased 6 months after CR. The % changes of the antioxidative/oxidative stress ratio was positively correlated with the % changes of V̇O2 AT, and negatively correlated with the % changes of the BNP. Conclusion These results suggest that intensive supervised CR significantly improved exercise capacity, which may be attributable to an adaptive response involving more efficient oxidative metabolites or the increased capacity of endogenous anti-oxidative systems in patients with cardiovascular diseases.

Relationship between chronotropic incompetence and β-blockers based on changes in chronotropic response during cardiopulmonary exercise testing

Background Chronotropic incompetence (CI), an attenuated heart rate (HR) response to exercise, is common in patients with cardiovascular disease. The aim of this study was to assess changes in the chronotropic response (CR) during cardiopulmonary exercise testing (CPET) in patients undergoing cardiac rehabilitation and investigate the effects of β-blockers. Methods Patients undergoing cardiac rehabilitation performed CPET. Failure to achieve 80% of the age-predicted maximal HR (APMHR) defined CI. Values of the metabolic chronotropic relationship (MCR) were calculated from the ratio of the HR reserve to metabolic reserve at 4 stages, warm-up (MCR-Wu), anaerobic threshold (MCR-AT), respiratory compensation (MCR-Rc), and peak point (MCR-Pk), using the Wilkoff model. In patients who showed an increase in MCR at ≥ 3 of the 4 exercise stages, CR was considered to have improved. Results Patients with high BNP levels (≥ 80 pg/ml) had a lower MCR at all stages compared with those with low BNP levels (< 80 pg/ml). Of the 80 patients, 47 showed an increase in both peak VO2 and AT, and of these 31 (66.0%) were taking β-blockers. Improvement in CR was observed in 30 of 47 patients with CI, and 70% of these were taking β-blockers. In patients not taking β-blockers, MCR-AT was lower than MCR-Rc, whereas in those taking β-blockers MCR-AT was higher than MCR-Rc. Conclusions An attenuated HR response may occur during the early stages of exercise. The HR response according to the presence or absence of β-blockers is clearly identifiable by comparing MCR-AT and MCR-Rc using the Wilkoff model.