Haruhiko Madarame

Cross-transfer effects of resistance training with blood flow restriction.

PURPOSE This study investigated whether muscle hypertrophy-promoting effects are cross-transferred in resistance training with blood flow restriction, which has been shown to evoke strong endocrine activation. METHODS Fifteen untrained men were randomly assigned into the occlusive training group (OCC, N = 8) and the normal training group (NOR, N = 7). Both groups performed the same unilateral arm exercise (arm curl) at 50% of one-repetition maximum (1RM) without occlusion (three sets, 10 repetitions). Either the dominant or nondominant arm was randomly chosen to be trained (OCC-T, NOR-T) or to serve as a control (OCC-C, NOR-C). After the arm exercise, OCC performed leg exercise with blood flow restriction (30% of 1RM, three sets, 15-30 repetitions), whereas NOR performed the same leg exercise without occlusion. The training session was performed twice a week for 10 wk. In a separate set of experiments, acute changes in blood hormone concentrations were measured after the same leg exercises with (N = 5) and without (N = 5) occlusion. RESULTS Cross-sectional area (CSA) and isometric torque of elbow flexor muscles increased significantly in OCC-T, whereas no significant changes were observed in OCC-C, NOR-T, and NOR-C. CSA and isometric torque of thigh muscles increased significantly in OCC, whereas no significant changes were observed in NOR. Noradrenaline concentration showed a significantly larger increase after leg exercise with occlusion than after exercises without occlusion, though growth hormone and testosterone concentrations did not show significant differences between these two types of exercises. CONCLUSION The results indicate that low-intensity resistance training increases muscular size and strength when combined with resistance exercise with blood flow restriction for other muscle groups. It was suggested that any circulating factor(s) was involved in this remote effect of exercise on muscular size.

Effects of low-intensity resistance exercise with blood flow restriction on coagulation system in healthy subjects

Recent studies have demonstrated that even a low‐intensity resistance exercise can effectively induce muscle hypertrophy and strength increase when combined with moderate blood flow restriction (BFR) into the exercising muscle. Although serious side effects of low‐intensity resistance exercise with BFR have not been reported, a concern of thrombosis has been suggested, because this type of exercise is performed with restricted venous blood flow and pooling of blood in extremities. Thus, the purpose of this study was to investigate the effects of low‐intensity resistance exercise with BFR on coagulation system in healthy subjects. Ten healthy men (25·1 ± 2·8 year) performed four sets of leg press exercises with and without BFR (150–160 mmHg) at an intensity of 30% of one‐repetition maximum (1RM). In each exercise session, one set with 30 repetitions was followed by three sets with 15 repetitions. Blood samples were taken before, and 10 min, 1, 4 and 24 h after the exercise. Prothrombin fragment 1 + 2 (PTF) and thrombin–antithrombin III complex (TAT) were measured as markers of thrombin generation, whereas D‐dimer and fibrin degradation product (FDP) were measured as markers of intravascular clot formation. Changes in plasma volume (PV) were calculated from haemoglobin and hematocrit values. PV reduction was significantly greater after the exercise with BFR than without (P<0·05). However, neither markers of thrombin generation nor intravascular clot formation increased after the exercises. These results suggest that low‐intensity resistance exercise with BFR does not activate coagulation system in healthy subjects.

Effect of very low-intensity resistance training with slow movement on muscle size and strength in healthy older adults

We previously reported that low‐intensity [50% of one repetition maximum (1RM)] resistance training with slow movement and tonic force generation (LST) causes muscle hypertrophy and strength gain in older participants. The aim of this study was to determine whether resistance training with slow movement and much more reduced intensity (30%1RM) increases muscle size and strength in older adults. Eighteen participants (60–77 years) were randomly assigned to two groups. One group performed very low‐intensity (30% 1RM) knee extension exercise with continuous muscle contraction (LST: 3‐s eccentric, 3‐s concentric, and 1‐s isometric actions with no rest between each repetition) twice a week for 12 weeks. The other group underwent intermitted muscle contraction (CON: 1‐s concentric and 1‐s eccentric actions with 1‐s rest between each repetition) for the same time period. The 1RM, isometric and isokinetic strengths, and cross‐sectional image of the mid‐thigh obtained by magnetic resonance imaging were examined before and after the intervention. LST significantly increased the cross‐sectional area of the quadriceps muscle (5·0%, P<0·001) and isometric and isokinetic knee extension strengths (P<0·05). CON failed to increase muscle size (1·1%, P = 0·12), but significantly improved its strength (P<0·05). These results indicate that even if the intensity is as low as 30% 1RM, LST can increase muscle size and strength in healthy older adults. The large total contraction time may be related to muscle hypertrophy and strength gain. LST would be useful for preventing sarcopenia in older individuals.

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.

Endocrine responses to upper- and lower-limb resistance exercises with blood flow restriction

To compare endocrine responses to low-intensity resistance exercise with blood flow restriction (BFR) for upperlimb (UL) and lower-limb (LL) muscles, we measured blood lactate, plasma noradrenaline, and serum growth hormone (GH), testosterone, cortisol and insulin-like growth factor-I (IGF-I) before and after the UL (biceps curl and triceps press down) and LL (leg extension and leg curl) exercises with BFR in nine men (26.3 +/- 3.1 yr). The load of 30% of one-repetition maximum (1RM) was used in all the exercises, in which the first set of 30 repetitions was followed by the second and third sets to failure. In each exercise program, the proximal portions of their upper arms (UL) or thighs (LL) were compressed bilaterally by elastic belts. Both the UL and LL caused significant increases in lactate, noradrenaline, GH, testosterone, cortisol, and IGF-I concentrations when compared to the pre-exercise values. A significant difference between the UL and LL was observed only in the area under the curve (AUC) of serum GH concentration, indicating that the LL induced greater GH response than did the UL. The greater GH secretion following the LL may be more advantageous for muscle hypertrophy induced by a long-term training period.

Blood flow-restricted training does not improve jump performance in untrained young men.

The purpose of this study was to investigate the effect of blood flow-restricted training (BFRT) on jump performance in relation to changes in muscle strength. Seventeen untrained young men were assigned into either BFRT or normal training (NORT) groups and performed low-intensity [30-40% of one-repetition maximum (1RM)] resistance exercise (horizontal squat, 3-4 sets × 15-30 repetitions) twice a week for 10 weeks. The BFRT performed the exercise with their proximal thighs compressed by air-pressure cuffs for the purpose of blood flow restriction. Squat 1RM, muscle cross-sectional area (CSA) of quadriceps femoris, and countermovement jump (CMJ) height were measured before and after the 10-wk training period. Squat 1RM increased greater in BFRT than in NORT (19.3% vs. 9.7%, P < 0.01). Although the CSA increase was independent of groups, it tended to be larger in BFRT than in NORT (8.3% vs. 2.9%, P = 0.094). On the other hand, CMJ height did not change after the training (P = 0.51). In conclusion, the present study showed that BFRT induced muscle hypertrophy and strength increase, whereas it did not increase CMJ height in previously untrained young men. It is suggested that BFRT is ineffective in improving jump performance.

Postexercise blood flow restriction does not enhance muscle hypertrophy induced by multiple-set high-load resistance exercise

To test the applicability of postexercise blood flow restriction (PEBFR) in practical training programmes, we investigated whether PEBFR enhances muscle hypertrophy induced by multiple‐set high‐load resistance exercise (RE). Seven men completed an eight‐week RE programme for knee extensor muscles. Employing a within‐subject design, one leg was subjected to RE + PEBFR, whereas contralateral leg to RE only. On each exercise session, participants performed three sets of unilateral knee extension exercise at approximately 70% of their one‐repetition maximum for RE leg first, and then performed three sets for RE + PEBFR leg. Immediately after completion of the third set, the proximal portion of the RE + PEBFR leg was compressed with an air‐pressure cuff for 5 min at a pressure ranging from 100 to 150 mmHg. If participants could perform 10 repetitions for three sets in two consecutive exercise sessions, the work load was increased by 5% at the next exercise session. Muscle thickness and strength of knee extensor muscles were measured before and after the eight‐week training period and after the subsequent eight‐week detraining period. There was a main effect of time but no condition × time interaction or main effect of condition for muscle thickness and strength. Both muscle thickness and strength increased after the training period independent of the condition. This result suggests that PEBFR would not be an effective training method at least in an early phase of adaptation to high‐load resistance exercise.