Eisuke Ochi

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.

Dietary apple polyphenols have preventive effects against lengthening contraction-induced muscle injuries.

We examined whether polyphenols from dietary apple have protective effects against exercise-induced muscle strain injury. Sixteen male Wistar rats were randomly assigned into the apple polyphenol (APP; N=8) and control (CON; N=8) groups. The APP and the CON groups were fed diets with and without 5% APP, respectively. After a 3-wk feeding period, the gastrocnemii of the animals were subject to lengthening contractions with electrical stimulation and forced ankle dorsiflexion. Isometric torques were measured before and after the lengthening contractions and on days 1, 2, 3, 5, and 7 after the contractions. On day 7, the animals were sacrificed and the gastrocnemii harvested. Thiobarbituric-acid-reactive substances, protein carbonyl, and mRNA of antioxidative proteins in the muscles were quantified. The APP group had significantly lower torque deficits than the CON group on days 3, 5, and 7 after the eccentric contractions. The thiobarbituric-acid-reactive substances and protein carbonyl levels in the case of the APP group were significantly lower than those in the case of the CON group. The APP group had significantly higher glutathione-S-transferase alpha1 mRNA levels than the CON group. Therefore, we conclude that dietary APPs have protective effects against lengthening contraction-induced muscle injury.

Muscular hypertrophy and changes in cytokine production after eccentric training in the rat skeletal muscle.

Ochi, E, Nakazato, K, and Ishii, N. Muscular hypertrophy and changes in cytokine production after eccentric training in the rat skeletal muscle. J Strength Cond Res 25(8): 2283-2292, 2011—We investigated the time course effects of eccentric training on muscular size, strength, and growth factor/cytokine production by using an isokinetic-exercise system for rats. Male Wistar rats (n = 34) were randomly assigned into 4 groups: 5 session eccentric-training group (ECC5S, n = 10); 5 session sham-operated group (CON5S, n = 10); 10 session eccentric-training group (ECC10S, n = 7); 10 session sham-operated group (CON10S, n = 7). In each group, a session of either training or sham operation was performed every 2 days. The training consisted of 4 sets of forced dorsiflexion (5 repetitions) combined with electric stimulation of plantar flexors. The wet weight of medial gastrocnemius muscle did not increase significantly after 5 sessions of training, whereas that after 10 sessions of training significantly increased with a concomitant increase in the cross-sectional area (CSA) of muscle fibers (weight, p < 0.05; fiber CSA, p < 0.001). Interleukin (IL)-6 in ECC5S and ECC10S groups showed significant increases (p < 0.01), whereas those of tumor necrosis factor (TNF)-α and IL-10 did not. The phospho-stat-3 showed a significant increase in ECC10S (p < 0.001) but not in ECC5S. Myostatin and follistatin also showed significant differences only between ECC10S and CON10S (p < 0.05). The results showed that repeated sessions of eccentric training for 20 days cause increases in muscular size and strength associated with increases in IL-6, follistatin, phospho-stat-3, and a decrease in myostatin. The delayed responses of IL-6, myostatin, phospho-stat-3, and follistatin would be due to the chronic effects of repeated training and possibly important for muscular hypertrophy.

Elevation of myostatin and FOXOs in prolonged muscular impairment induced by eccentric contractions in rat medial gastrocnemius muscle

This study aimed to investigate torque deficit and activation of protein synthesis and/or protein degradation signaling pathways during the early and recovery phase after high- and low-velocity eccentric contractions (ECs). Male Wistar rats (n = 36) were randomly divided into fast angular velocity ECs group (FAST; 180 degrees/s; n = 12), slow ECs group (SLOW; 30 degrees/s; n = 12), and control group (control; n = 12). ECs comprised four sets of five forced dorsiflexions combined with electrical stimulation of the plantar flexors. Isometric tetanic torque was measured before and after ECs. Tissue contents of Akt(P) (P, phosphorylated), mammalian target of rapamycin (mTOR)(P), 70-kDa ribosomal protein S6 kinase (P70S6k), P70S6k(P), forkhead transcription factor 1 of the O class (FOXO1), FOXO1(P), FOXO3, FOXO3(P), myostatin, and activin receptor type IIB (ActRIIB) were measured. The isometric tetanic torque after ECs was significantly lower in FAST than in SLOW (days 1, 3, and 5, P < 0.05; day 2, P < 0.01). The ratio of P70S6k(P) against total P70S6k on days 2 and 7 was significantly higher in SLOW than in the control. The ratio of FOXO1 against total FOXO1, the ratio of FOXO3a against total FOXO3a, and myostatin on days 2 and 7 were significantly higher in FAST than in the control, while that of ActRIIB on day 7 was significantly lower in SLOW than in the other two groups. These results suggest that EC intensity plays a key role in impairment of muscular function and activation of protein synthesis and/or protein degradation signaling pathways.

The Cartilage Intermediate Layer Protein Gene is Associated with Lumbar Disc Degeneration in Collegiate Judokas

Lumbar disc degeneration is frequently seen in athletes. Lumbar disc diseases include a spectrum of diseases and/or symptoms, including lumbar disc degeneration. Some reports suggest an association between lumbar disc diseases and a functional single-nucleotide polymorphism (SNP;1184T/C, rs 2073711) of the cartilage intermediate layer protein ( CILP) gene. We hypothesized that lumbar disc degeneration occurrence may be significantly associated with SNP variants at the CILP gene in Japanese collegiate judo athletes. Eighty-nine Japanese judo athletes participated in this study. T2-weighted magnetic resonance imaging was used to define lumbar disc degeneration. Genotyping of the CILP gene (1184T/C) was performed using DNA sequencing. By using logistic regression analysis, significant associations of lumbar disc degeneration with the CILP C allele (odds ratio=4.1, 95% confidence interval: 1.57-10.71) and body weight (odds ratio=1.06, 95% confidence interval: 1.02-1.09) were observed. We conclude that the CILP gene 1184T/C polymorphism is a significant risk factor for lumbar disc degeneration occurrence in Japanese collegiate judo athletes.

Importance of both fatness and aerobic fitness on metabolic syndrome risk in Japanese children.

Associations between body mass index (BMI), peak oxygen consumption (VO2peak), and metabolic syndrome (MetS) risk factors have not been adequately studied in Japanese children. Here the relationships between these parameters and the threshold aerobic fitness level necessary for low MetS risk were determined. The participants (299 children; 140 boys and 159 girls, aged 9.1 ± 0.3 years) were divided into four groups using the medians of predicted VO2peak (pVO2peak) and BMI. MetS risk scores were calculated using z-scores. Receiver Operating Characteristic analysis was used to determine the threshold aerobic fitness level necessary for low MetS risk. The MetS risk score of the High BMI group was significantly higher than that of the Low BMI group for both sexes (p < 0.0001). However, the High BMI/High Fitness group had a significantly lower MetS risk score than the High BMI/Low Fitness group for both sexes. The pVO2peak cut-off values for low MetS risk were 47.9 and 44.9 ml/kg/min for boys and girls, respectively. Our results suggest that improvements in both fatness and aerobic fitness are important for decreasing MetS risk. We also confirmed the pVO2peak of cut-off values necessary for low MetS risk in Japanese children.

Association between the stress fracture and bone metabolism/quality markers in lacrosse players

Background Overuse injury including stress fracture is a serious problem for athletes. Recently, the importance of bone metabolism and quality as factors preventing overuse injury has been increasingly recognized. Hence, we hypothesized that markers of bone metabolism and quality are related to overuse injuries. Methods The subjects, which were elite university lacrosse players (male, n = 35; age, 19.8 ± 1.1; female, n = 49; age, 20.0 ± 1.0), were divided into a stress fracture group and a control group. We measured the subjects’ physical characteristics (height, weight, body mass index, and body fat) and bone architecture was evaluated using quantitative ultrasound. Bone alkaline phosphatase, N-telopeptide cross-link of type I collagen, tartrate-resistant acid phosphatase 5b (TRAP-5b), homocysteine, and pentosidine were measured from blood samples obtained from all subjects. Results No significant difference was observed between groups with respect to height, weight, body mass index, and body fat, as well as quantitative ultrasound. Further, there were no significant differences in the levels of bone alkaline phosphatase, N-telopeptide cross-link of type I collagen, or TRAP-5b between stress fracture and control groups in all subjects and in male subjects. However, a significant increase in TRAP-5b level was observed in the stress fracture group compared with the control in the female subjects (409.9 ± 209.3 and 318.6 ± 81.6 mU/dL, respectively; P < 0.05). Homocysteine and pentosidine did not differ between groups. Conclusion These results suggest that osteoclast activity of female athletes with stress fractures may be enhanced by TRAP-5b.

Differences of activation pattern and damage in elbow flexor muscle after isokinetic eccentric contractions

BACKGROUND: Eccentric contractions (ECC)-induced muscle damage and activation pattern are not fully understood. OBJECTIVE: To investigate the activation level and damage in each muscle and site after ECC. METHODS: Eleven men performed 30 isokinetic ECC of the elbow flexors. Maximal voluntary isometric contraction (MVC) torque, range of motion of the elbow joint (ROM), delayed onset muscle soreness (DOMS), transverse relaxation time (T2), and cross-sectional area (CSA) were measured immediately before, immediately after, and 1, 3, 5 days after ECC. RESULTS: MVC and ROM significantly decreased while DOMS significantly increased until 3 days after ECC. The CSA of the brachialis significantly increased after ECC. The T2 in biceps brachii and middle and distal brachialis increased significantly at post ( p< 0.01) day 1 (middle; p< 0.01, distal; biceps brachii, p< 0.05, brachialis, p< 0.01), and day 3 (middle; p< 0.01, distal; biceps brachii, p< 0.05, brachialis, p< 0.01). In addition, after 5 days only the distal brachialis has shown a significant increase ( p< 0.01). CONCLUSIONS: Following maximal ECC the activation pattern and muscle damage differ among the elbow flexors depending upon the individual muscle and site of recording.

Eccentric contractions of gastrocnemius muscle-induced nerve damage in rats

We examined the effects of gastrocnemius eccentric contractions (ECs) on the sciatic nerve in rats. Methods: Rats were divided randomly into the following 3 groups: control, 180EC (ECs with 180°/s angular velocity), and 30EC (ECs with 30°/s angular velocity). Twenty ECs were induced by electrical stimulation of the gastrocnemius. On days 3, 7, and 10 after the ECs, nerve conduction velocity (NCV) was measured, and sciatic nerve branches were harvested for analysis. Results: A significant decrease in NCV was observed between the control and day‐7 180EC. Significant reduction in the levels of myelin sheath protein zero (p0) between day 7 and day 3 180EC and a significant increase of macrophage‐related protein and tyrosine kinase receptor C were observed between day 7 180EC and day 7 30EC. Conclusions: ECs with fast angular velocities induce functional and structural damage in innervating nerve. Muscle Nerve 50: 87–94, 2014

Isokinetic strength and anaerobic/intermittent capacity of Japanese lacrosse players

We investigated and compared isokinetic strength, anaerobic and intermittent capacity of mens lacrosse players at various playing positions. The subjects were 33 mens lacrosse players (attacker; AT n = 11, defender; DF n = 10, midfielder; MF n = 12). Measurements contained physical characteristics, isokinetic strength, anaerobic capacity (maximal anaerobic power; Pmax, Wingate anaerobic power; WAnP), and 10-s (R10IC) and 20-s (R20IC) rest intervals of intermittent capacity. Knee flexor strength at angular velocities of 60 ◦ /s and 180 ◦ /s was significantly greater in DF players than in AT players ( p< 0.05), 300 ◦ /s was significantly higher in MF players than in AT players ( p< 0.05). With regard to Pmax, MF players showed significantly higher values compared with AT players ( p< 0.05), and WAnP of MF players showed significantly higher values compared with that of AT and DF players (AT; p< 0.01, DF; p< 0.05). R10IC was significantly higher in MF players than in both AT and DF players (AT: p< 0.05, DF: p< 0.05), whereas R20IC was significantly higher in MF players than in AT players ( p< 0.05). These results indicate that knee flexor strength, anaerobic capacity, and intermittent capacity are greater in µ Ft han the other positions in mens lacrosse.