[This corrects the article DOI: 10.3389/fspor.2023.1144484.].

UNASSIGNED: Eccentric muscle contractions elicit distinct physiological responses, including modulation of the cytokine profile. Although relevant for rehabilitation, the effect of eccentric muscle training on the immune system has never been investigated in multiple sclerosis (MS).
UNASSIGNED: Examine the immediate cytokine response of interleukin-4 (IL-4), IL-6, IL-10, IL-17a, interferon-gamma, and tumor necrosis factor-alpha after a moderate eccentric training session in individuals with MS. Additionally, further investigate the association between systemic cytokine levels at rest and clinical measures of mobility and lower limb functional strength.
UNASSIGNED: Observational study.
UNASSIGNED: The first session included blood sampling for baseline cytokine measures. Subsequently, the participant completed a battery of clinical assessments related to mobility and lower limb strength, that is, the Timed-Up-and-Go Test, Five-Repetition-Sit-to-Stand-Test (5STS), Four-Square-Step-Test, and Two-Minute-Walk-Test. The second session included the eccentric exercise training session, followed by a second blood sampling to assess the acute cytokine response to the eccentric training bout. This session comprised 10 exercises concentrating on the strength of the trunk and lower extremities.
UNASSIGNED: Twenty-seven people with MS (pwMS), with a mean age of 40.1 years, participated in the study. No difference was demonstrated in the cytokine concentration values between baseline and immediately after the eccentric training session. The 5STS explained 30.3% of the variance associated with interferon-gamma, 14.8% with IL-4, and 13.8% with IL-10.
UNASSIGNED: An eccentric training bout does not impact cytokine concentration in the blood and, consequently, does not boost a pro-inflammatory response, thus, it can be performed on pwMS in a rehabilitation setting.
A strength-lengthening exercise session doesn’t affect inflammation markers in people with multiple sclerosis The article explores how a specific type of exercise, called eccentric muscle training, affects people with multiple sclerosis (MS). Eccentric muscle training involves exercises where the muscle lengthens under tension, like when you slowly lower a heavy object. This type of exercise is known for causing unique physical responses, including changes in certain proteins in the blood that help control the immune system and inflammation. The main goal of the study was to see if a session of eccentric muscle training would change the levels of these proteins, called cytokines, in the blood of people with MS immediately after exercise. The cytokines studied included IL-4, IL-6, IL-10, IL-17a, INF-γ, and TNF-α. These proteins are important because they help regulate inflammation and immune responses. The researchers also wanted to know if there was any connection between the levels of these proteins at rest and measures of mobility and leg strength. Twenty-seven people with MS took part in the study. Their average age was 40.1 years. In the first session, blood samples were taken to measure the baseline levels of these proteins, and various tests were conducted to assess mobility and leg strength. In the second session, participants completed an eccentric training session, and another blood sample was taken immediately after to see if there were any immediate changes in the protein levels. The results showed no significant differences in the protein levels before and after the exercise session. This suggests that a single session of eccentric muscle training does not cause an immediate inflammatory response in the blood. Therefore, this type of exercise can be safely included in rehabilitation programs for people with MS without the risk of causing harmful inflammation. Overall, the study supports the safety of eccentric muscle training for people with MS and provides valuable insights into its immediate effects on the immune system.

OBJECTIVE: The optimal approach to hamstring training is heavily debated. Eccentric exercises reduce injury risk; however, it is argued that these exercises transfer poorly to improved hamstring function during sprinting. Some argue that other exercises, such as isometric exercises, result in better transfer to running gait and should be used when training to improve performance and reduce injury risk. Given the performance requirements of the hamstrings during the terminal swing phase, where they are exposed to high strain, exercises should aim to improve the torque production during this phase. This should improve the hamstrings\' ability to resist overlengthening consequently, improving performance and limiting strain injury. Most hamstring training studies fail to assess running kinematics postintervention. Of the limited evidence available, only eccentric exercises demonstrate changes in swing-phase kinematics following training. Studies of other exercise modalities investigate effects on markers of performance and injury risk but do not investigate changes in running kinematics.
CONCLUSIONS: Despite being inconsistent with principles of transfer, current evidence suggests that eccentric exercises result in transfer to swing-phase kinematics. Other exercise modalities may be effective, but the effect of these exercises on running kinematics is unknown.

UNASSIGNED: The characteristics of Proximal Hamstring Tendinopathy (PHT) include deep, localized pain in the region of the ischial tuberosity. Chronic lesions are often found in long-distance runners. Compression of the tendon and shear force at its insertion at the ischial tuberosity during hip flexion/adduction is a key etiologic factor. The aim of this case report is to analyze the effectiveness of an exercise protocol with progression of tendon loading in PHT in an amateur runner, by assessing pain and functional capacity.
UNASSIGNED: The subject was a 30-year-old male runner. After participating in a 10km race, he experienced an insidious onset of deep buttock pain in the right ischial tuberosity. His pain was aggravated by running on sloped roads and prolonged sitting on hard surfaces, particularly while driving. The visual analog scale (VAS) for pain, the Puranen-Orave test (PO), the Bent-Knee stretch test (BK stretch), the supine plank test, the Victorian Institute of Sport Assessment-proximal hamstring tendons (VISA-H) questionnaire, and the sciatic nerve mobility (via the Slump test) were assessed. The intervention involved a 12-week progressive loading exercise program divided into four phases.
UNASSIGNED: The initial pain was reduced at 6 weeks of intervention and further decreased at 12 weeks (VAS from 7, to 5 and to 1). Function increased at 6 weeks and at 12 weeks (VISA-H from 23, to 53, to 80). Sciatic nerve mobility was normal.
UNASSIGNED: The progression of training in a subject with PHT tendon injury based on isometric exercise, concentric/eccentric, energy storage, progressively increasing hip flexion was beneficial, increasing function and decreasing pain. Studies with a larger sample size and a more precise methodological design would be necessary to support this type of intervention in clinical practice.
UNASSIGNED: 5.

Whether eccentric exercise involves active fascicle stretch is unclear due to muscle-tendon unit (MTU) series compliance. Therefore, this study investigated the impact of changing the activation timing and level (i.e., preactivation) of the contraction on muscle fascicle kinematics and kinetics of the human tibialis anterior during dynamometer-controlled maximal voluntary MTU-stretch-hold contractions. B-mode ultrasound and surface electromyography were used to assess muscle fascicle kinematics and muscle activity levels, respectively. Although joint kinematics were similar among MTU-stretch-hold contractions (∼40° rotation amplitude), increasing preactivation increased fascicle shortening and stretch amplitudes (9.9-23.2 mm, P ≤ 0.015). This led to increasing positive and negative fascicle work with increasing preactivation. Despite significantly different fascicle kinematics, similar peak fascicle forces during stretch occurred at similar fascicle lengths and joint angles regardless of preactivation. Similarly, residual force enhancement (rFE) following MTU stretch was not significantly affected (6.5-7.6%, P = 0.559) by preactivation, but rFE was strongly correlated with peak fascicle force during stretch (rrm = 0.62, P = 0.003). These findings highlight that apparent eccentric exercise causes shortening-stretch contractions at the fascicle level rather than isolated eccentric contractions. The constant rFE despite different fascicle kinematics and kinetics suggests that a passive element was engaged at a common muscle length among conditions (e.g., optimal fascicle length). Although it remains unclear whether different fascicle mechanics trigger different adaptations to eccentric exercise, this study emphasizes the need to consider MTU series compliance to better understand the mechanical drivers of adaptation to exercise.NEW & NOTEWORTHY Apparent eccentric exercises do not result in isolated eccentric contractions, but shortening-stretch contractions at the fascicle level. The amount of fascicle shortening and stretch depends on the preactivation during the exercise and cannot be estimated from the muscle-tendon unit (MTU) or joint kinematics. As different fascicle mechanics might trigger different adaptations to eccentric exercise, muscle-tendon unit series compliance and muscle preactivation need to be considered when eccentric exercise protocols are designed.

The objective of this research is to examine the impact of eccentric training on hamstring flexibility and strength in young dancers during the concluding stages of their foundational dance training program. A total of 24 female, second-year dance students from Hebei Normal University were selected as participants. They were divided into three distinct groups: Nordic hamstring exercise and single-leg deadlift group (NHE&SLD), forward bending exercises and standing leg lift group (FBE&SLL), and a control group (CG). The study was designed around a 6-week training regimen. An isokinetic dynamometer was used to measure seated knee flexor-extensor strength, while electronic goniometry was employed to measure hamstring flexibility in the supine position. Paired sample t-tests were conducted within each group, and one-way analysis of covariance (ANCOVA) was utilized for comparisons between groups. In the NHE&SLD group, significant disparities were observed in both concentric (T = - 5.687, P = 0.001) and eccentric (T = - 3.626, P = 0.008) hamstring strength pre and post-intervention. The pre-intervention dominant leg concentric strength test values significantly influenced the post-intervention outcomes (F = 5.313, P = 0.001, η2 = 0.840). Similarly, the pre-intervention dominant leg eccentric strength test values impacted the post-intervention results (F = 4.689, P = 0.043, η2 = 0.190). Following the intervention, the NHE&SLD group displayed marked changes in the active straight leg raising angle on both left (T = - 4.171, P = 0.004) and right (T = - 6.328, P = 0.001) sides. The FBE&SLL group also revealed significant changes in the active straight leg raising angle on both left (T = - 4.506, P = 0.003) and right (T = - 4.633, P = 0.002) sides following the intervention. The pre-intervention left leg concentric strength test value significantly influenced the post-intervention outcomes (F = 25.067, P = 0.001, η2 = 0.556). Likewise, the pre-intervention right leg eccentric strength test value significantly influenced the post-intervention results (F = 85.338, P = 0.01, η2 = 0.810). Eccentric training can better enhance the flexibility and strength of hamstring muscles in dance students. Traditional stretching training significantly improves the flexibility of the hamstring muscles. Eccentric training has more training benefits than traditional stretching training. It is recommended for dance students to use eccentric training when increasing hamstring flexibility and strength.

Objective: The study compared the activities of the surface electromyography (sEMG) of trunk and hip muscles during single-leg Romanian deadlift (SLRDL) exercises using a flywheel and dumbbell with different loading positions (ipsilateral and contralateral). Method: Twelve active male subjects with at least 2 years of strength training experience (age: 26.7 ± 3.3 years; weight: 73.9 ± 6.2 kg) participated in this study. sEMG in the percentage of maximum voluntary isometric contraction of four SLRDL exercises (ipsilateral and contralateral loading position for dumbbell and flywheel) in a randomized order for superior gluteus maximus (SGM), inferior gluteus maximus (IGM), gluteus medius (GM), biceps femoris (BF), erector spinae (ES), external oblique (EO), and adductor longus (AL) were measured. One-way repeated measure ANOVA with Bonferroni adjustment (statistical significance at 0.05) and the non-clinical magnitude-based decision with a standardized difference were performed for statistical analysis. Results: The overall results demonstrated a very high level of SGM (105.4%-168.6%) and BF (69.6%-122.4%) muscle activities. A significant moderate increase of sEMG signals in GM, IGM, and ES (dominant side) and a large increase in SGM activity during concentric action when the loading position of flywheel SLRDL was changed from ipsilateral to the contralateral side. No significant difference was observed between flywheel and dumbbell SLRDL exercises. Conclusion: Strength coaches may adopt dumbbell or flywheel SLRDL exercises using the contralateral loading position to simultaneously strengthen the hip extensors and trunk stabilizers effectively.

There is considerable debate about the existence of a real eccentric overload in flywheel exercises. This study aimed to analyse the differences in concentric: eccentric mechanical output ratios between different loads and variables in the flywheel squat exercise. Twenty physically active men (22.9 ± 2.2 years, height: 1.8 ± 0.1 m, weight: 79.6 ± 8.2 kg) performed a loading test using five moments of inertia. Angular speed was measured using a rotary encoder, while the vertical force was measured using force plates. For each variable (angular speed, angular acceleration, power, vertical force, and torque), mean and peak values were calculated for concentric and eccentric phases to allow comparisons across the loads. We tested the possible differences in Load × Phase (concentric and eccentric) and Load × Variable. The level of significance was established as p < 0.05. A significant Load × Phase interaction was found in mean angular speed, peak vertical force, peak angular acceleration, peak power and peak torque. Higher eccentric overload values were observed with speed-derived variables (angular speed, angular acceleration and power). In conclusion, speed-derived peak variables and lower loads are more likely to show an eccentric overload and can be used to monitor responses to flywheel training.

There is a growing body of evidence showing the importance of physical activity against civilization-induced metabolic diseases, including type 2 diabetes (T2DM) and obesity. Eccentric contraction, when skeletal muscles generate force by lengthening, is a unique type of skeletal muscle activity. Eccentric contraction may lead to better power production characteristics of the muscle because eccentric contraction requires less energy and can result in higher tension. Therefore, it is an ideal tool in the rehabilitation program of patients. However, the complex metabolic effect (i.e., fat mass reduction, increased lipid oxidation, improvement in blood lipid profile, and increased insulin sensitivity) of the eccentric contraction alone has scarcely been investigated. This paper aims to review the current literature to provide information on whether eccentric contraction can influence metabolic health and body composition in T2DM or obesity. We also discussed the potential role of myokines in mediating the effects of eccentric exercise. A better understanding of the mechanism of eccentric training and particularly their participation in the regulation of metabolic diseases may widen their possible therapeutic use and, thereby, may support the fight against the leading global risks for mortality in the world.

OBJECTIVE: To evaluate the adherence to treatment and efficacy of an eccentric-based training (ECC) program on peripheral muscle function and functional exercise capacity in patients with chronic obstructive pulmonary disease (COPD).
METHODS: Prospective, assessor-blinded, randomized controlled trial.
METHODS: The cardiopulmonary rehabilitation unit of a tertiary subacute referral center.
METHODS: Thirty (N=30) stable inpatients (mean age 68±8 years; FEV1 44±18% of predicted) with COPD were included in the study.
METHODS: Inpatients were randomly assigned to 4 weeks of a combined endurance and resistance ECC (n=15) or conventional training (CON; n=15).
METHODS: Quadriceps peak torque (PT) was the primary outcome measure for muscle function. Rate of force development (RFD), muscle activation and quality (quadriceps PT/leg lean mass), 6-min walk distance (6MWD), 4-meter gait speed (4mGS), 10-meter gait speed, 5-repetition sit-to-stand (5STS), dyspnea rate, and mortality risk were the secondary outcomes. Evaluations were performed at baseline and repeated after 4 weeks and 3 months of follow-up.
RESULTS: Quadriceps PT, RFD, and muscle quality improved by 17±23% (P<.001), 19±24%, and 16±20% (both P<.05) within the ECC group. Besides, a significant between-group difference for RFD (56±94 Nm/s, P=.038) was found after training. Both groups showed clinically relevant improvements in 6MWD, 4mGS, dyspnea rate, and mortality risk, with no significant differences between groups.
CONCLUSIONS: Combined endurance and resistance ECC improved lower limbs muscle function compared with CON in inpatients with COPD. In contrast, ECC did not further improve functional performance, dyspnea, and mortality risk. ECC may be of particular benefit to effect on skeletal muscle function in patients with COPD.