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Purpose: Changes in elbow flexion torque and biceps brachii electromyogram (EMG) activity over 30 repetitive maximal voluntary concentric-only (CON-only), eccentric-only (ECC-only), and alternative concentric and eccentric (CON-ECC, 30 concentric + 30 eccentric) contractions were examined to compare their muscle fatigue profiles., Methods: Fifteen healthy young men performed CON-only, ECC-only and CON-ECC in their maximal effort between 10° and 100° elbow flexion on an isokinetic dynamometer at an angular velocity of 30°/s with a 3-s rest between contractions in a randomised order with ≥ 3 days between conditions. Changes in torque and EMG over the repeated contractions and maximal voluntary isometric contraction (MVC-ISO) torque with EMG before the first contraction and immediately after the last contraction were compared among conditions by two-way repeated measures analysis of variance., Results: The torque decreased (p < 0.01) from the first to 30th contraction in CON-only (- 49.5 ± 11.0%), ECC-only (- 32.2 ± 7.4%), and concentric (- 62.3 ± 8.7%) as well as eccentric phase (- 58.9 ± 9.3%) in CON-ECC (- 46.0 ± 12.3% overall). The magnitude of the decrease in the torque was greater (p < 0.01) for the CON-only than ECC-only, and the concentric than an eccentric phase in the CON-ECC. However, MVC-ISO torque decreased (p < 0.01) similarly after CON-only (- 42.9 ± 13.8%) and ECC-only (- 40.1 ± 9.2%), which was smaller (p < 0.01) than CON-ECC (- 56.8 ± 9.2%). EMG over contractions decreased (p < 0.01) for all conditions similarly from the first to the last contraction (- 28.5 ± 26.8%), and EMG in MVC-ISO also decreased similarly for all conditions (- 24.7 ± 35.8%)., Conclusion: These results suggest greater fatigue resistance in repetitive maximal eccentric than concentric contractions, but the fatigue assessed by MVC-ISO does not show it., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Detrusor instability is one of the most common problems in patients with lower urinary tract obstructive diseases, such as benign prostatic hyperplasia. Adenosine triphosphate (ATP) has been associated as a neuronal component in the detrusor instability., Materials and Methods: Ninety-six female Splague-Dawley rats were studied. Outflow obstructions were created by ligature of the urethra over which a catheter was placed. Changes in the bladder capacity, and an isovolumetric contractile response to pharmacologic antagonists were studied in the obstructed rats for a period of from one day to four weeks., Results: The bladder capacity of rats obstructed for four weeks increased significantly. Maximum bladder contraction pressure with the use of atropine medication was inhibited in 60 percent and, 30 percent of in the control group, respectively. The inhibitory effect of the maximum bladder contraction pressure by the pyridoxalphosphate-6-azophenyl-2', 4'-disulphonate (PPADS) dosage after the atropine dosage was not recognized it in the control group, but the effect was recognized powerfully in the obstructed group., Conclusion: In the obstructed bladder rat, strong rise of the bladder contraction by P2X receptor with a lower urinary obstruction was accepted, and that result reflects positively. Therefore, it was guessed that the result was an end of the compensatory mechanism of unstable bladder.

Background: The Nordic hamstring exercise (NHE) is useful for preventing hamstring strain injuries. However, its adoption rates in the sports field are currently low, necessitating a safe and efficient introduction. Hypothesis/Purpose: The purpose was to examine the relationship between the eccentric force during the NHE and the one repetition maximum of deadlift. It was hypothesized that the eccentric force during the NHE would be correlated with the one repetition maximum (1RM) of the deadlift. Study design: Cross-sectional study. Methods: Healthy student rugby players with no history of hamstring tears were recruited to participate. The peak eccentric forces during the NHE, which is the vertical peak force on the part holding the leg, were measured in both legs, while gradually leaning forward to a prone position over three seconds. The 1RM of deadlift was calculated from the weight that could be raised three times during a deadlift (x kg) using the estimated formula (x kg / 0.93). The correlation between the left and right peak eccentric forces during the NHE, the total left and right forces, and the 1RM of the deadlift was examined using Spearman's rank correlation coefficient, with all values corrected for body mass. Results: During the NHE, the peak eccentric force of the right and left legs and the total peak eccentric force of both legs were 3.8 ± 1.1 N/BM, 3.8 ± 1.2 N/BM, and 7.6 ± 2.1 N/BM, respectively. The 1RM of deadlift was 1.9 ± 0.3 kg/BM. Weak correlations (r = 0.34–0.37) were found between the 1RM of the deadlift and the peak eccentric force in the right and left legs and the total peak eccentric force of both legs. Conclusion: The present study revealed a weak correlation between the peak eccentric force during the NHE and 1RM of deadlift Level of Evidence: 2c [ABSTRACT FROM AUTHOR]

Our previous study showed that daily six maximal eccentric contractions that were performed 5 days a week for 4 weeks increased maximal voluntary isometric (MVC‐ISO), concentric (MVC‐CON), and eccentric contraction (MVC‐ECC) strength of the elbow flexors and muscle thickness of biceps brachii and brachialis (MT) by 8.3 ± 4.9%, 11.1 ± 7.4%, 13.5 ± 11.5%, and 10.6 ± 5.1%, respectively. In the present study, we tested the hypothesis that the muscle strength and MT would still increase when the training intensity was reduced to 2/3 or 1/3 of the peak MVC‐ECC torque. Thirty‐six healthy young (19–24 years) adults who had not performed resistance training were placed to three groups (n = 12/group): 2/3MVC or 1/3MVC that performed six eccentric contractions with 2/3 or 1/3 MVC‐ECC load using a dumbbell 5 days a week for 4 weeks or control group that did not perform any training. Changes in the MVC‐ISO, MVC‐CON, MVC‐ECC torque, and MT before and after the 4‐week period were compared among the groups and with the group of the previous study in which six maximal eccentric contractions were performed 5 days a week for 4 weeks (MVC group; n = 12). The control and 1/3MVC groups showed no significant changes in any measures. Significant (p < 0.05) increases in MVC‐ISO (10.3 ± 11.4%), MVC‐CON (10.9 ± 9.5%), and MVC‐ECC (9.3 ± 8.8%) torque and MT (10.1 ± 9.2%) were observed for the 2/3MVC group. These changes were not significantly different from those of the MVC group. These results suggest that the 2/3‐intensity eccentric contractions with a dumbbell are as effective as maximal‐intensity isokinetic eccentric contractions to induce muscle adaptations. [ABSTRACT FROM AUTHOR]

Purpose: Our previous study showed that one 3-s maximal eccentric contraction a day performed 5 days a week for 4 weeks (5DW) increased maximal voluntary contraction (MVC) strength of the elbow flexors more than 10%. The present study examined whether muscle strength would still increase when the frequency was reduced to 2 days or 3 days per week. Methods: Twenty-six healthy young adults were recruited in the present study and placed to two groups (n = 13/group) based on the weekly frequency of the one 3-s maximal eccentric contraction for two (2DW) or three days per week (3DW) for 4 weeks. Changes in MVC-isometric, MVC-concentric, MVC-eccentric torque of the elbow flexors, and muscle thickness of biceps brachii and brachialis (MT) before and after the 4-week training were compared between 2DW and 3DW groups, and also compared to the 5DW group in the previous study. Results: The 2DW group showed no significant changes in MVC torque. Significant (P < 0.05) increases in MVC-concentric (2.5 ± 10.4%) and MVC-eccentric (3.9 ± 4.9%) torque were observed for the 3DW group, but the magnitude of the increase was smaller (P < 0.05) than that presented by the 5DW group (12.8 ± 9.6%, 12.2 ± 7.8%). No significant changes in MT were evident for any of the groups. Conclusion: These results suggest that at least three days a week are necessary for the one 3-s maximal eccentric contraction to be effective for increasing muscle strength, and more frequent sessions in a week (e.g., 5 days) appear to induce greater increases in muscle strength. [ABSTRACT FROM AUTHOR]

Our previous study found that one maximal voluntary eccentric contraction (MVC‐ECC) performed daily for 5 days a week for 4 weeks increased MVC‐ECC, isometric (MVC‐ISO), and concentric contraction (MVC‐CON) torque of the elbow flexors more than 10%. The present study investigated the effects of six maximal voluntary eccentric contractions on the MVC torques and biceps brachii and brachialis muscle thickness (MT). Thirty‐six healthy young adults were placed to one of the three groups (N = 12 per group); the 6 × 1 group that performed one set of six contractions once a week, the 6 × 5 group that performed one set of six contractions a day for 5 days a week, and the 30 × 1 group that performed five sets of six contractions a day in a week. The training duration was 4 weeks for all groups, and changes in MVC‐ECC, MVC‐CON and MVC‐ISO torque, and MT before and after the 4‐week training were compared among the groups. The 6 × 1 group did not show significant changes in muscle strength and MT. Significant (p < 0.05) increases in MVC‐ECC (13.5 ± 11.5%), MVC‐ISO (9.3 ± 5.5%), MVC‐CON torque (11.1 ± 7.4%) were evident for the 6 × 5 group only, and increases in MT were found for the 6 × 5 (10.4 ± 4.4%) and 30 × 1 (8.0 ± 5.8%) groups without a significant difference. These results suggest that performing a small number of eccentric contractions 5 days a week is more effective for increasing muscle strength than performing a larger volume of eccentric contractions once a week. However, it appears that training volume is a factor for muscle hypertrophy in a short‐term training. [ABSTRACT FROM AUTHOR]

Kiyono, R, Onuma, R, Yasaka, K, Sato, S, Yahata, K, and Nakamura, M. Effects of 5-week foam rolling intervention on range of motion and muscle stiffness. J Strength Cond Res 36(7): 1890–1895, 2022—In clinical and sports settings, foam rolling (FR) intervention is widely used to increase the range of motion (ROM). However, the chronic effects of FR on ROM and muscle stiffness are unclear. The aim of this study was to investigate the effects of 5-week FR intervention on dorsiflexion ROM (DFROM) and shear elastic modulus of the medial gastrocnemius (MG) muscle. Accordingly, 30 healthy young adults were enrolled and randomly assigned to either the FR or control group with the former receiving 90 seconds of FR thrice per week over 5 weeks. Thereafter, DFROM, passive torque at DFROM, and shear elastic modulus of the MG during passive ankle dorsiflexion were assessed using a dynamometer and ultrasonography before and after 5 weeks. Our results showed that the FR group exhibited a significant increase in DFROM (Δ = 11.7%, p < 0.05, effect size = 0.39), but no changes in passive torque at DFROM, and shear elastic modulus at 0° and 10° dorsiflexion. Moreover, significant correlations were observed between change in DFROM and change in passive torque at DFROM in the FR group (r s = 0.607, p = 0.016). These results suggested that FR was an effective method to increase DFROM given its ability to change passive torque at DFROM (stretch tolerance) without altering muscle stiffness. [ABSTRACT FROM AUTHOR]

The present study compared a 3‐s isometric maximal voluntary contraction (MVC), concentric MVC and eccentric MVC of the elbow flexors performed daily for 5 days a week for 4 weeks for changes in muscle strength and thickness. Young sedentary individuals were assigned to one of three training groups (n = 13 per group) that performed either 3‐s isometric, concentric, or eccentric MVC once a day for 20 days, or to a control group (n = 10) that had measurements without training. The participants in the isometric group performed isometric MVC at 55° (0.96 rad) elbow flexion, and those in the concentric or eccentric group performed concentric MVC or eccentric MVC between 10° (0.17 rad) and 100° (1.75 rad) elbow flexion at 30°/s (0.52 rad/s) on an isokinetic dynamometer. MVC isometric torque at 20° (0.35 rad), 55° (0.96 rad), and 90° (1.57 rad) elbow flexion, MVC concentric and eccentric torque at 30°/s (0.52 rad/s) and 180°/s (3.14 rad/s), and muscle thickness (MT) of biceps brachii and brachialis were measured before and several days after the 20th exercise session. The control group did not show any changes. The eccentric group showed increases (p < 0.01) in isometric (three angle average: 10.2 ± 6.4%), concentric (two velocity average: 12.8 ± 9.6%), and eccentric MVC torque (12.2 ± 7.8%). An increase (p < 0.05) was limited for isometric MVC torque (6.3 ± 6.0%) in the concentric group, and for eccentric MVC torque (7.2 ± 4.4%) in the isometric group. No significant changes in MT were evident for all groups. Performing one 3‐s MVC a day increased muscle strength, but eccentric MVC produced more potent effects than isometric or concentric MVC. [ABSTRACT FROM AUTHOR]

The present study compared two unilateral arm curl resistance exercise protocols with a different starting and finishing elbow joint angle in the same ROM for changes in elbow flexors strength and muscle thickness of the trained and non-trained arms. Thirty-two non-resistance trained young adults were randomly assigned to one of the three groups: extended joint training (0°–50°; EXT, n = 12); flexed joint training (80°–130°; FLE, n = 12); and non-training control (n = 8). The exercise training was performed by the dominant arms twice a week for 5 weeks with gradual increases in the training volume over 10 training sessions, and the non-dominant (non-trained) arms were investigated for the cross-education effect. Maximal voluntary contraction torque of isometric (MVC-ISO), concentric (MVC-CON), and eccentric contractions (MVC-ECC), and thickness (MT) of biceps brachii and brachialis of the trained and non-trained arms were assessed at baseline and 4–8 days after the last training session. The control group did not show significant changes in any variables. Significant (P < 0.05) increases in MVC-ISO torque (16.2 ± 12.6%), MVC-CON torque (21.1 ± 24.4%), and MVC-ECC torque (19.6 ± 17.5%) of the trained arm were observed for the EXT group only. The magnitude of the increase in MT of the trained arm was greater (P < 0.05) for EXT (8.9 ± 3.9%) than FLE (3.4 ± 2.7%). The cross-education effect was evident for MVC-ISO (15.9 ± 14.8%) and MVC-CON (16.7 ± 20.0%) torque of the EXT group only. These results suggest that resistance training at the extended elbow joint induces greater muscle adaptations and cross-education effects than that at flexed elbow joint. [ABSTRACT FROM AUTHOR]

Background: Unilateral resistance training increases the strength of the contralateral non-trained homologous muscles known as the cross-education effect. We tested the hypothesis that unilateral eccentric resistance training (ET) would induce greater and longer-lasting cross-education effect when compared with concentric resistance training (CT). Methods: Young (20–23 y) participants were allocated to ET (5 males, 4 females) or CT (5 males, 4 females) group that performed unilateral progressive ET or CT of the elbow flexors, twice a week for 5 weeks (10 sessions) followed by a 5-week detraining, and control group (7 males, 6 females) that did not perform any training. Maximum voluntary isometric contraction torque of the elbow flexors (MVIC), one-repetition maximum of concentric dumbbell curl (1-RM), and biceps brachii and brachialis muscle thickness (MT) were measured from the trained and non-trained arms before, several days after the last training session, and 5 weeks later. A ratio between the trained and non-trained arms for the change in MVIC or 1-RM from pre- to post-training (cross-body transfer ratio) was compared between ET and CT groups. Results: The control group did not show significant changes in any variables. Both ET and CT increased (P < 0.05) MVIC (22.5 ± 12.3 % vs. 26.0 ± 11.9 %) and 1-RM (28.8 ± 6.6 % vs. 35.4 ± 12.9 %) of the trained arm without a significant difference between groups. MVIC was maintained after detraining for ET but returned to the baseline for CT, and 1-RM was maintained after detraining for both ET and CT. For the non-trained arm, MVIC (22.7 ± 17.9 % vs. 12.2 ± 10.2 %) and 1-RM (19.9 ± 14.6 % vs. 24.0 ± 10.6 %) increased similarly (P > 0.05) after ET and CT, and MVIC returned to the baseline after detraining, but 1-RM was maintained for both groups. An increase (P < 0.05) in MT was found only after ET for the trained arm (7.1 ± 6.1 %). The cross-body transfer ratio for MVIC was greater (P < 0.05) for ET (90.9 ± 46.7 %) than CT (49.0 ± 30.0 %). Conclusions: These results did not support the hypothesis and showed similar changes in the most of the variables between ET and CT for the trained and non-trained arms, and strong cross-education effects on MVIC and 1-RM, but less detraining effect after ET than CT on MVIC of the trained arm. Trial registration: University Hospital Medical Information Network Clinical Trials Registry (UMIN000044477; Jun 09, 2021). [ABSTRACT FROM AUTHOR]

Purpose: Static stretching (SS) is performed in various settings, but there is no consensus about the effects of SS programmes on changes in muscle morphofunction. This study aimed to investigate the effects of a high-volume SS programme on muscle strength and architecture. Methods: Sixteen healthy young male adults participated, and the dominant leg was defined as the intervention side, with the non-dominant leg as the control side. Stretching exercises were performed two times per week (6 sets of 5 min, totally 30 min per session,) for 5-week using a stretching board under the supervision of the research team. Before and after SS intervention programme, plantar-flexor strength (maximum voluntary isometric contraction, MVC-ISO; maximum voluntary concentric contraction, MVC-CON) and architecture (muscle thickness, pennation angle, and fascicle length) were measured via dynamometer and ultrasound, respectively. Results: Following the SS-training programme, significant increases were observed for stretching side in MVIC-ISO at neutral ankle position (p = 0.02, d = 0.31, Δ = 6.4 ± 9.9%) and MVC-CON at 120°/s (p = 0.02, d = 0.30, Δ = 7.8 ± 9.1%), with no significant change on the control side. There was no significant change in any measure of muscle architecture for both intervention and control sides. Conclusion: Five-week high-volume SS induced positive changes on some measures of muscle strength but not hypertrophy of plantar-flexor muscles. Even with a volume much greater than already tested, the low strain offered by the SS per set seems be insufficient to induce architectural changes on skeletal muscle. [ABSTRACT FROM AUTHOR]

This study investigated the effects of static stretching (SS) delivered with the same load but using two protocols – high-intensity and short-duration and low-intensity and long-duration – on range of motion (ROM) and muscle stiffness. A total of 18 healthy students participated in the study. They randomly performed high-intensity and short-duration (120% and 100 s) or low-intensity and long-duration (50% and 240 s) SS. Outcomes were assessed on ROM, passive torque at dorsiflexion ROM, and shear elastic modulus of the medial gastrocnemius before and after static stretching. The results showed that ROM increased significantly at post-stretching compared to that at pre-stretching in both high-intensity and short-duration [+6.1° ± 4.6° (Δ25.7 ± 19.9%)] and low-intensity and long-duration [+3.6° ± 2.3° (Δ16.0 ± 11.8%)]. Also, the ROM was significantly higher at post-stretching in high-intensity and short-duration conditions than that in low-intensity and long-duration. The passive torque at dorsiflexion ROM was significantly increased in both high-intensity and short-duration [+5.8 ± 12.8 Nm (Δ22.9 ± 40.5%)] and low-intensity and long-duration [+2.1 ± 3.4 Nm (Δ6.9 ± 10.8%)] conditions, but no significant differences were observed between both conditions. The shear elastic modulus was significantly decreased in both high-intensity and short-duration [−8.8 ± 6.1 kPa (Δ − 38.8 ± 14.5%)] and low-intensity and long-duration [−8.0 ± 12.8 kPa (Δ − 22.2 ± 33.8%)] conditions. Moreover, the relative change in shear elastic modulus in the high-intensity and short-duration SS was significantly greater than that in low-intensity and long-duration SS. Our results suggest that a higher intensity of the static stretching should be conducted to increase ROM and decrease muscle stiffness, even for a short time. [ABSTRACT FROM AUTHOR]

This correction notice is for an article titled "Weekly minimum frequency of one maximal eccentric contraction to increase muscle strength of the elbow flexors" published in the European Journal of Applied Physiology. The correction addresses an error in the affiliation details for authors Kazunori Nosaka and Masatoshi Nakamura. The correct affiliations are provided for both authors. The correction notice also includes a note from the publisher stating that Springer Nature remains neutral regarding jurisdictional claims and institutional affiliations. The authors of the article are Riku Yoshida, Kazuki Kasahara, Yuta Murakami, Shigeru Sato, Midori Tanaka, Kazunori Nosaka, and Masatoshi Nakamura. [Extracted from the article]