Takanobu Okamoto

Acute effects of self-myofascial release using a foam roller on arterial function.

Abstract Okamoto, T, Masuhara, M, and Ikuta, K. Acute effects of self-myofascial release using a foam roller on arterial function. J Strength Cond Res 28(1): 69–73, 2014—Flexibility is associated with arterial distensibility. Many individuals involved in sport, exercise, and/or fitness perform self-myofascial release (SMR) using a foam roller, which restores muscles, tendons, ligaments, fascia, and/or soft-tissue extensibility. However, the effect of SMR on arterial stiffness and vascular endothelial function using a foam roller is unknown. This study investigates the acute effect of SMR using a foam roller on arterial stiffness and vascular endothelial function. Ten healthy young adults performed SMR and control (CON) trials on separate days in a randomized controlled crossover fashion. Brachial-ankle pulse wave velocity (baPWV), blood pressure, heart rate, and plasma nitric oxide (NO) concentration were measured before and 30 minutes after both SMR and CON trials. The participants performed SMR of the adductor, hamstrings, quadriceps, iliotibial band, and trapezius. Pressure was self-adjusted during myofascial release by applying body weight to the roller and using the hands and feet to offset weight as required. The roller was placed under the target tissue area, and the body was moved back and forth across the roller. In the CON trial, SMR was not performed. The baPWV significantly decreased (from 1,202 ± 105 to 1,074 ± 110 cm·s−1) and the plasma NO concentration significantly increased (from 20.4 ± 6.9 to 34.4 ± 17.2 &mgr;mol·L−1) after SMR using a foam roller (both p < 0.05), but neither significantly differed after CON trials. These results indicate that SMR using a foam roller reduces arterial stiffness and improves vascular endothelial function.

Repeated cessation and resumption of resistance training attenuates increases in arterial stiffness.

Although high-intensity resistance training (RT) increases arterial stiffness, removing weightlifting stimuli returns arterial stiffness to baseline levels within relatively short periods during 4-8 weeks. This study investigates the effects of repeated RT cessation and resumption on arterial stiffness. Eighteen young healthy subjects were randomly assigned to a group that performed continuous RT (CRT, n=9) and a group that performed periodic RT (PRT, n=9). Both groups performed RT at 75% of one repetition maximum for 3 days per week. The CRT group continuously trained for 16 weeks, whereas the PRT group performed 3 cycles of 4 weeks training, with 2 weeks detraining intervals between cycles. The carotid-femoral pulse wave velocity in the CRT group significantly increased (P<0.05) at 4, 6, 10, 12, 16 and 20 weeks from baseline, whereas in the PRT group it significantly increased (P<0.05) after 4, 10 and 16 weeks from baseline, and was significantly lower (P<0.05) than that of the CRT group after 6, 10, 12, 16 and 20 weeks. Muscle mass and strength in the both groups significantly increased after 16 weeks from baseline and persisted for 20 weeks (P<0.05). These results suggest that PRT, including short-term repeated cessation and resumption, attenuates increases in arterial stiffness.

Relationship between plasma endothelin-1 concentration and cardiovascular responses during high-intensity eccentric and concentric exercise.

The present study investigates the relationship between plasma endothelin‐1 (ET‐1) concentrations and cardiovascular responses during eccentric (ECC) and concentric (CON) resistance exercises. Eight healthy males (aged 24·3 ± 1·2 years) performed dynamic forearm exercises for 60 s at an angular velocity of 60º s−1. Each test comprised 60‐s high‐intensity (80% of peak torque) bouts of randomly selected ECC and CON contractions, and the plasma ET‐1 concentrations were measured before and after each type of contraction. Systolic pressure (SBP), diastolic pressure (DBP), pulse pressure and heart rate (HR) during ECC and CON contraction were also measured. Mean arterial pressure (MAP) was calculated from SBP and DBP. The rate‐pressure product (RPP) was calculated from SBP and HR. The plasma ET‐1 concentration was significantly increased after CON, compared with ECC contraction (P<0·01). Moreover, SBP, DBP, MAP and RPP were significantly increased (P<0·05, P<0·01, P<0·001, respectively) during CON, compared with ECC contraction. Correlations between plasma ET‐1 concentration and MAP were not significant during ECC contraction, but significantly positive during CON contraction (P<0·05). These results showed that CON contraction is associated with ET‐1 production and a greater increase in blood pressure compared with ECC contraction.

Low-intensity resistance exercise with slow lifting and lowering does not increase noradrenalin and cardiovascular responses

The aim of this study was to investigate the effect of low‐intensity resistance exercise with slow lifting and lowering (LSL) on plasma endothelin‐1 (ET‐1) and noradrenalin concentrations in young healthy adults. Eight healthy males participated in this study (age 19·0 ± 0·5 years, mean ± SD). The LSL performed the 10 repetitions with 3 s eccentric (lowering phase) and 3 s concentric (lifting phase) muscle actions. The high‐intensity resistance exercise with normal lifting and lowering (HNL) performed the 10 repetitions with 1 s eccentric (lowering phase) and 1 s concentric (lifting phase) muscle actions. The load was set to 40% of one repetition maximal (1RM) for LSL and 80% of 1RM for HNL. Plasma ET‐1 and noradrenalin concentrations were measured before and after each type of exercise. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), pulse pressure (PP) and heart rate (HR) during LSL and HNL were measured. The rate‐pressure product (RPP) was calculated from SBP and HR. There were no significant differences in the plasma ET‐1 concentration between LSL and HNL. However, the plasma noradrenalin concentration was significantly increased after HNL, compared with LSL (P<0·001). SBP, DBP, PP, MAP, HR and RPP during LSL were significantly lower compared with HNL (P<0·05: PP and HR; P<0·01: RPP; P<0·001: SBP, DBP and MAP). These results suggested that LSL may suppress the increase in plasma noradrenalin concentrations and cardiovascular responses.

The ACTN3 R577X genotype is associated with muscle function in a Japanese population

Homozygosity for the common nonsense polymorphism R577X in the α-actinin-3 gene (ACTN3) causes complete α-actinin-3 deficiency in fast-twitch skeletal muscle fibers. This study investigated whether the ACTN3 R577X polymorphism affects fitness status using a battery of tests in a large Japanese cohort. In the present study, 1227 subjects (age: 25-85 years) were genotyped for the ACTN3 R577X polymorphism (rs1815739) using a TaqMan SNP genotyping assay (Applied Biosystems). All subjects were divided into 2 groups based on their age (<55 years and ≥55 years). All subjects completed a questionnaire about exercise habits and were subjected to a battery of tests to assess their fitness status (including grip strength test, chair stand test, and 8-foot walking test). A significant association between the ACTN3 R577X genotype and chair stand test performance was observed in the group of men ≥55 using ANCOVA adjusted for age and exercise habits (p = 0.036). The ACTN3 R577X genotype accounted for 2.5% of the variability in the results of the chair stand test among men in the ≥55 age group. Moreover, for the ≥55 age group, performance in the chair stand test was lower among those with the XX genotype than among those with the RR genotype (p = 0.024) or RX genotype (p = 0.005), unlike results for the <55 age group. No significant difference was noted for hand grip strength or 8-foot walking time. Thus, our results suggest that the ACTN3 R577X genotype is associated with lower-extremity muscle function in the Japanese population.

Association between ACTN3 R577X Polymorphism and Trunk Flexibility in 2 Different Cohorts

α-Actinin-3 (ACTN3) R577X polymorphism is associated with muscular strength and power. This study was performed to investigate the association between ACTN3 R577X polymorphisms and flexibility as another component of fitness in 2 cohorts. Cohort 1 consisted of 208 men and 568 women (ages 23-88), while Cohort 2 consisted of 529 men and 728 women (ages 23-87). All participants were recruited from the Tokyo metropolitan area and underwent a battery of tests to assess their grip strength and sit-and-reach flexibility. Genotyping results were analyzed for ACTN3 (rs1815739) polymorphism using the TaqMan approach. In Cohort 1, sit-and-reach in the RR genotype (35.3±0.7 cm) was significantly lower than those in the RX and XX genotypes (37.2±0.3 cm) even after adjusting for sex, age, and exercise habit as covariates (P<0.01). In Cohort 2, sit-and-reach tended to be lower in RR (38.1±0.6 cm) than in RX and XX (39.1±0.3 cm), but the differences were not significant (P=0.114). Analysis in pooled subjects indicated that RR was associated with significantly lower flexibility than RX and XX (P=0.009). The RR genotype of ACTN3 R577X in the general Japanese population showed lower flexibility compared to the RX and XX genotypes.

Effects of Menstrual Phase–dependent Resistance Training Frequency on Muscular Hypertrophy and Strength

Abstract Sakamaki-Sunaga, M, Min, S, Kamemoto, K, and Okamoto, T. Effects of menstrual phase–dependent resistance training frequency on muscular hypertrophy and strength. J Strength Cond Res 30(6): 1727–1734, 2016—The present study investigated how different training frequencies during menstrual phases affect muscle hypertrophy and strength. Fourteen eumenorrheic women performed 3 sets of arm curls (8–15 repetitions) until failure for 12 weeks. Depending on the menstrual cycle phase, each subject trained each arm separately after either a 3- or a 1-d·wk−1 training protocol during the follicular phase (FP-T) and a 3- or 1-d·wk−1 training protocol during the luteal phase (LP-T). Cross-sectional area (CSA), 1 repetition maximum, and maximum voluntary contraction significantly increased 6.2 ± 4.4, 36.4 ± 11.9, and 16.7 ± 5.6%, respectively (p ⩽ 0.05 vs. before training), in the FP-T group and 7.8 ± 4.2, 31.8 ± 14.1, and 14.9 ± 12.7%, respectively (p ⩽ 0.05 vs. before training), in the LP-T group. Changes in CSA between the FP-T and the LP-T groups significantly and positively correlated (r = 0.54, p ⩽ 0.05). There were no major differences among the different training protocols with regard to muscle hypertrophy and strength. Therefore, we suggest that variations in female hormones induced by the menstrual cycle phases do not significantly contribute to muscle hypertrophy and strength gains during 12 weeks of resistance training.

Acute effect of brisk walking with graduated compression stockings on vascular endothelial function and oxidative stress

The purpose of this study was to investigate the acute effect of brisk walking with and without graduated compression stockings (GCSs) on vascular endothelial function and oxidative stress. Ten young healthy subjects walked briskly for 30 min with (GCS trial) and without (CON trial) GCSs in a randomized crossover trial. Brachial artery flow‐mediated dilation (FMD) was measured as the per cent rise in the peak diameter from the baseline value at prior occlusion at each FMD measurement using B‐mode ultrasonography before and 30 min after walking in the two trials. Derivatives of reactive oxygen metabolites (d‐ROM), as an index of products of reactive oxygen species, and biological anti‐oxidant potential (BAP), as an index of anti‐oxidant potential, were also measured using a free radical elective evaluator before and 30 min after walking in both trials. FMD significantly decreased after brisk walking in both trials (P<0·05). However, FMD after brisk walking in the GCS trial was significantly higher than that in the CON trial (P<0·05). The d‐ROM did not change before and after both trials, whereas the BAP significantly increased after walking in the GCS trial (P<0·05). These findings demonstrate that brisk walking while wearing GCSs suppresses the decrease in FMD and increases BAP.

Low-Intensity Resistance Training after High-Intensity Resistance Training can Prevent the Increase of Central Arterial Stiffness

Although high-intensity resistance training increases arterial stiffness, low-intensity resistance training reduces arterial stiffness. The present study investigates the effect of low-intensity resistance training before and after high-intensity resistance training on arterial stiffness. 30 young healthy subjects were randomly assigned to a group that performed low-intensity resistance training before high-intensity resistance training (BLRT, n=10), a group that performed low-intensity resistance training after high-intensity resistance training (ALRT, n=10) and a sedentary control group (n=10). The BLRT and ALRT groups performed resistance training at 80% and 50% of one repetition maximum twice each week for 10 wk. Arterial stiffness was measured using carotid-femoral and femoral-ankle pulse wave velocity (PWV). One-repetition maximum strength in the both ALRT and BLRT significantly increased after the intervention (P<0.05 to P<0.01). Both carotid-femoral PWV and femoral-ankle PWV after combined training in the ALRT group did not change from before training. In contrast, carotid-femoral PWV after combined training in the BLRT group increased from before training (P <0.05). Femoral-ankle PWV after combined training in the both BLRT and ALRT groups did not change from before training. These results suggest that although arterial stiffness is increased by low-intensity resistance training before high-intensity resistance training, performing low-intensity resistance training thereafter can prevent the increase of arterial stiffness.

Effect of Resistance Exercise on Arterial Stiffness during the Follicular and Luteal Phases of the Menstrual Cycle

Acute high-intensity resistance exercise increases arterial stiffness. Changes in blood concentrations of estrogen and progesterone associated with the menstrual cycle affect the degree of arterial stiffness. Therefore, high-intensity resistance exercise may affect arterial stiffness differently depending on the phase of the menstrual cycle. The purpose of this study was to investigate the effects of different phases of the menstrual cycle on arterial stiffness after one session of resistance exercise. The participants were 9 eumenorrheic females (21.3±0.8 years). All participants performed 5 sets of 5 repetitions using 80% of the one repetition maximum (1RM) bench press and 5 sets of 10 repetitions using 70% of the 1RM biceps curl during both the follicular and luteal phases. Brachial-ankle pulse wave velocity (baPWV), blood pressure, and heart rate were measured before (baseline) and at 30 and 60 min after completing the resistance exercises. During the follicular phase, baPWV was significantly increased at 30 and 60 min after the resistance exercise compared with baseline (P<0.05), whereas during the luteal phase, no significant differences were observed after the resistance exercise. These results suggest that high-intensity resistance exercise affects arterial stiffness differently depending on the phase of the menstrual cycle.