Correlation of Eccentric Strength, Reactive Strength, and Leg Stiffness With Running Economy in Well-Trained Distance Runners.

ABSTRACT: Li, F, Newton, RU, Shi, Y, Sutton, D, and Ding, H. Correlation of eccentric strength, reactive strength, and leg stiffness with running economy in well-trained distance runners. J Strength Cond Res 35(6): 1491-1499, 2021-Neuromuscular characteristics play a critical role in distance running performance; however, their relationship with running economy (RE) remains unclear. The purpose of this study was to evaluate the correlations between 1 repetition maximum (1RM) strength, eccentric strength, reactive strength, leg stiffness, and RE at 12-16 km·h-1 among well-trained male runners. Twenty-eight male collegiate distance runners participated in test sessions on 3 separate days. In the first session, their 1RM squat strength, countermovement jump (CMJ), and drop jump performances were measured. In the second session, the leg press (LP) eccentric and concentric peak force, and leg stiffness (Kleg) were evaluated. In the final session, 12, 14, and 16 km·h-1 RE, blood lactate concentration, and maximum oxygen uptake were measured. There were significant relationships between the LP eccentric peak force, eccentric:concentric peak force ratios (Efl:Cex), RE at speeds of 12, 14, and 16 km·h-1 (r = -0.527 to -0.630; p < 0.01), reactive strength index (r = -0.419 to -0.572; p < 0.05), and Kleg (r = -0.686 to -0.761; p < 0.001) were significantly correlated with RE at 12, 14, and 16 km·h-1. No significant association was found between LP concentric peak force, 1RM squat strength, CMJ, and RE at any speed (p > 0.05). Superior RE among distance runners may be related to greater eccentric strength, elastic energy utilization, and stiffer lower limbs during running but not to maximal muscle strength per se. Coaches should focus on these neuromuscular characteristics to improve running performance.

MicroRNA-146b acts as a potential tumor suppressor in human prostate cancer.

PURPOSE: MicroRNAs (miRs) act as either tumor suppressors or oncogenes and are frequently deregulated in cancers. Although downregulation of miR-146b has been reported in various cancers, its role in prostate cancer is totally unknown. METHODS: The miR-146b expression in 18 human prostate cancer lines with case-matched adjacent normal tissues was measured by quantitative RT-PCR. Furthermore, the expression levels of miR-146b in normal prostate and prostate cancer cell lines were assessed. Cell proliferation, apoptosis, migration and invasion assays were performed in overexpressing or knockdown miR-146b cells. RESULTS: miR-146b expression was significantly reduced in all prostate tumor tissues. Furthermore, miR-146b was significantly decreased in prostate cancer cells as compared to normal prostate cells. Loss-of-function and gain-of-function showed that miR-146b induced apoptosis and suppressed cell proliferation, migration and invasion of the prostate cancer cell lines. CONCLUSION: Our results demonstrated that miR-146b expression is downregulated in prostate tumor tissues and is a potential tumor suppressor miR, suggesting that miR-146b might be a potential clinical marker and therapeutic target for prevention and treatment of prostate cancer.

Lower Extremity Kinematic and Kinetic Characteristics as Effects on Running Economy of Recreational Runners.

PURPOSE: This study aimed to determine associations between running economy (RE) and running sagittal plane kinematic and kinetic parameters. METHOD: A total of 30 male recreational runners (age: 21.21 ± 1.22 yr, V̇O 2max : 54.61 ± 5.42 mL·kg -1 ·min -1 ) participated in two separate test sessions. In the first session, the participant's body composition and RE at 10 and 12 km·h -1 were measured. In the second session, measurements were taken for the sagittal plane of hip, knee, and ankle angles and range of motion (ROM), as well as ground reaction force. RESULTS: Moderate correlations were found between lower energy costs at 12 km·h -1 and smaller hip flexion at toe-off ( r = 0.373) as well as smaller peak hip flexion during stance ( r = 0.397). During the swing phase, lower energy costs at 10 km·h -1 were moderately correlated with smaller peak knee flexion and smaller knee flexion and extension ROM ( r = 0.366-0.443). Lower energy costs at 12 km·h -1 were moderately correlated with smaller peak hip and knee flexion as well as knee extension ROM ( r = 0.369-0.427). In terms of kinetics, there was a moderate correlation between higher energy costs at 10 km·h -1 and larger peak active force, as well as larger peak braking and propulsion force ( r = -0.470-0.488). Lower energy costs at 12 km·h -1 were moderately to largely correlated with smaller peak impact and braking force ( r = 0.486 and -0.500, respectively). Regarding the statistical parametric mapping analysis, most outcomes showed associations with RE at 10 km·h -1 , including knee flexion (42.5%-65.5% of the gait cycle), ankle plantarflexion (32.5%-36% of the gait cycle), active force (30.5%-35% of the stance phase), and propulsion force (68%-72.5% of the stance phase). Lower energy costs at 12 km·h -1 were correlated with smaller hip flexion (5.5%-12% and 66.5%-74%) and smaller knee flexion (57%-57.5%) during the running gait cycle. CONCLUSIONS: This study indicates that biomechanical factors are associated with RE in recreational runners. To design effective training methods to improve RE, coaches and runners should focus on the sagittal plane kinematics of the hip, knee, and ankle, as well as lower vertical and horizontal kinetic parameters.

Renal lipid accumulation and aging linked to tubular cells injury via ANGPTL4.

Renal tubular epithelial cells are vulnerable to stress-induced damage, including excessive lipid accumulation and aging, with ANGPTL4 potentially playing a crucial bridging role between these factors. In this study, RNA-sequencing was used to identify a marked increase in ANGPTL4 expression in kidneys of diet-induced obese and aging mice. Overexpression and knockout of ANGPTL4 in renal tubular epithelial cells (HK-2) was used to investigate the underlying mechanism. Subsequently, ANGPTL4 expression in plasma and kidney tissues of normal young controls and elderly individuals was analyzed using ELISA and immunohistochemical techniques. RNA sequencing results showed that ANGPTL4 expression was significantly upregulated in the kidney tissue of diet-induced obesity and aging mice. In vitro experiments demonstrated that overexpression of ANGPTL4 in HK-2 cells led to increased lipid deposition and senescence. Conversely, the absence of ANGPTL4 appears to alleviate the impact of free fatty acids (FFA) on aging in HK-2 cells. Additionally, aging HK-2 cells exhibited elevated ANGPTL4 expression, and stress response markers associated with cell cycle arrest. Furthermore, our clinical evidence revealed dysregulation of ANGPTL4 expression in serum and kidney tissue samples obtained from elderly individuals compared to young subjects. Our study findings indicate a potential association between ANGPTL4 and age-related metabolic disorders, as well as injury to renal tubular epithelial cells. This suggests that targeting ANGPTL4 could be a viable strategy for the clinical treatment of renal aging.

Prognostic value of E­26 transformation­specific­related gene in prostate cancer based on immunohistochemistry analysis.

E-26 transformation-specific-related gene (ERG) has been implicated in prostate cancer; however, its prognostic role remains unclear. Therefore, the present study aimed to investigate the association of ERG with the prognosis after radical prostatectomy in patients with prostate cancer. Patient data were collected at the Huadong Hospital, affiliated with Fudan University, between January 2016 and March 2020. ERG protein expression was detected using immunohistochemistry. Independent-sample t-tests and χ2 tests were used to evaluate prostate cancer prognosis depending on ERG levels. The Kaplan-Meier method was used to estimate biochemical failure-free survival (BFFS) and the log-rank test was used to test the distribution. Prognostic factors were determined using Cox regression analysis. The median patient age was 69 years (range, 47-82 years). The median prostate-specific antigen (PSA) and free-PSA levels before treatment were 9.58 ng/ml (range, 0.003-187.400 ng/ml) and 1.13 ng/ml (range, 0.0059-30.6100 ng/ml), respectively. ERG protein expression was positive in 43 (16.6%) and negative in 216 (83.4%) cases. The median follow-up period and BFFS were 30 and 28 months, respectively. There was a significant difference in biochemical recurrence (P=0.017) between patients with positive and negative ERG expression. Patients with positive ERG expression had significantly worse BFFS curves compared with those with negative ERG expression (P=0.0038). In the multivariate Cox regression analysis, positive ERG expression was found to be an independent prognostic factor in patients with prostate cancer who underwent radical prostatectomy (hazard ratio, 4.08; 95% confidence interval, 2.03-8.17; P=0.000074). In conclusion, positive ERG expression is an independent prognostic risk factor for prostate cancer. These findings may be valuable for improvements in the clinical application of ERG immunohistochemistry.

Long-term prognosis and prognostic factors of brachytherapy and propensity score matched comparisons of the outcomes between brachytherapy and radical prostatectomy: a retrospective cohort study.

Background: To report outcomes of patients undergoing brachytherapy (BT), investigate factors associated with biochemical progression-free survival (bPFS) and to compare its long-term prognosis with that of radical prostatectomy (RP) in localized prostate cancer. Methods: The clinical data of 87 elderly patients with localized prostate cancer who underwent BT at Huadong Hospital affiliated to Fudan University from January 2009 to December 2016 were retrospectively analyzed. Patient prognoses and associated factors were investigated using univariate and multivariate Cox regression models. The clinical data of the 142 patients with localized prostate cancer who underwent RP during the same period were also collected. By using propensity score matching (PSM), the 42 patients who underwent BT were matched to 42 patients who underwent RP, and the differences in the survival curves were investigated using the Kaplan-Meier method. Results: The median follow-up period of the patients who underwent BT was 101 months. The 5- and 10-year overall survival (OS) rates of the patients who underwent BT were 82.8% and 64.0%, respectively, while the 5- and 10-year bPFS rates were 97.2% and 87.5%, respectively. The preoperative clinical Tumor (T) stage was identified as a prognostic factor of bPFS, as patients who underwent BT whose clinical stage was T3 had a worse prognosis than those whose clinical stage was T1-T2 (HR =0.097, P=0.049). After PSM, the average follow-up time of the BT group was 90 months and that of the RP group was 94 months. No significant differences in bPFS or cause-specific survival were observed between the 2 groups. The OS of the RP group was significantly higher than that of the BP group (P=0.030). Among the patients with a prostate volume >35 mL, those who underwent BT had significantly higher pPFS than those who underwent RP (P=0.041). Conclusions: In the localized prostate cancer, BT and RP offered similar oncological control in the localized prostate cancer. Stage T3 prostate cancer who undergo BT was associated with worse biochemical failure and was the only variable significantly predictive of biochemical recurrence.

Construction of the structural equation model of badminton players' variable direction ability and its enlightenment to sports training.

BACKGROUND: With the continuous development of modern badminton, higher requirements were put forward for the comprehensive quality of athletes. Studies show that players' ability of changing direction play an important role in badminton competition. In the present study, the SpeedCourt test system was used to study factors of badminton players' variable direction ability. METHODS: A total of 101 badminton players were included. The SpeedCourt test system was used to test the variable direction ability of players through three categories: speed chase, jump and reaction. Principal component analysis and moment structure analysis were used to analyze the test data. RESULTS: Four influencing factors were found of badminton players' variable direction ability; these are moving speed, coordination, reaction, and explosive force. The structural equation model of variable direction ability and the 4 influencing factors fit well with the measured data. The correlation between variable direction ability and coordination was the highest (r=0.91), followed by moving speed (0.86), reaction (r=0.81), and lower extremity explosive force (r=0.79). CONCLUSIONS: This paper demonstrates the structural equation model of badminton players' ability to change direction from an empirical point of view, which lays a foundation for the study of badminton players' agility and provides a reference for sports practice.

Relationship Between Isokinetic Lower-Limb Joint Strength, Isometric Time Force Characteristics, and Leg-Spring Stiffness in Recreational Runners.

Neuromuscular characteristics, such as lower-limb joint strength and the ability to rapidly generate force, may play an important role in leg-spring stiffness regulation. This study aimed to investigate the relationship between isokinetic knee and ankle joint peak torque (PT), the force-time characteristics of isometric mid-thigh pull (IMTP), and leg stiffness (K leg)/vertical stiffness (K vert) in recreationally trained runners. Thirty-one male runners were recruited and underwent three separate tests. In the first session, the body composition, K leg, and K vert at running speeds of 12 and 14 km⋅h-1 were measured. In the second session, isokinetic knee and ankle joint PT at 60°â‹…s-1 were tested. The force-time characteristics of the IMTP were evaluated in the final session. Pearson's product-moment correlations, with the Benjamini-Hochberg correction procedure, showed that the knee flexor concentric and eccentric and extensor concentric PT (r = 0.473-0.654, p < 0.05) were moderate to largely correlated with K leg and K vert at 12 and 14 km⋅h-1. The knee extensor eccentric PT (r = 0.440, p = 0.050) was moderately correlated with the 14 km⋅h-1 K vert. The ankle plantar flexor concentric and dorsiflexor eccentric PT (r = 0.506-0.571, p < 0.05) were largely correlated with K leg at 12 km⋅h-1. The ankle plantar flexor concentric and eccentric and dorsiflexor eccentric PT (r = 0.436-0.561, p < 0.05) were moderate to largely correlated with K vert at 12 and 14 km⋅h-1. For IMTP testing, high correlation was only found between the IMPT peak force (PF) and K vert at 14 km⋅h-1 (r = 0.510, p = 0.014). Thus, superior leg-spring stiffness in recreational runners may be related to increased knee and ankle joint strength, eccentric muscular capacity, and maximal force production.

Concurrent complex and endurance training for recreational marathon runners: Effects on neuromuscular and running performance.

Marathon performance is influenced by factors such as aerobic capacity and those related to neuromuscular function. Complex training (CPX) is a multicomponent training method, wherein heavy strength and plyometric exercises alternate within a single session and is an effective method to improve neuromuscular adaptations. This study compared the effects of CPX, heavy strength training (HST) and endurance-strength (EST) combined with running endurance training on neuromuscular adaptations and running performance in 38 recreational marathoners (age:31.4 ± 3.8 years, VO2max:57.6 ± 6.8 ml·kg-1·min-1). Athletes were allocated in 3 groups: CPX, HST and EST and were tested for one maximum repetition strength (1RM), squat jump and countermovement jumps (SJ, CMJ), leg press (LP) concentric and eccentric strength, running economy (RE) and velocity at VO2max (vVO2max) before and after the 6-week intervention. CPX and HST were performed 2 times per week in conjunction with the running endurance training. RE and vVO2max improved in CPX and HST groups (p < 0.01, RE: -5% to -6.4%, vVO2max: 5.7% and 4.2%, respectively) with no change in EST. Similarly, all neuromuscular performance indicators improved in CPX and HST (p < 0.0167, 1RM strength:19.7% to 25.1%, SJ and CMJ: 5.3% to 11.6%, LP concentric and eccentric strength: 5.5% to 18.0%). In summary, 6-week of concurrent CPX or HST and endurance training resulted in similar improvement in maximum strength, RE, and vVO2max. Importantly, both CPX and HST training resulted in greater improvements in eccentric strength and RE compared to EST that performed concurrent endurance-strength and endurance training.

Effects of complex training versus heavy resistance training on neuromuscular adaptation, running economy and 5-km performance in well-trained distance runners.

BACKGROUND: Recently, much attention has been paid to the role of neuromuscular function in long-distance running performance. Complex Training (CT) is a combination training method that alternates between performing heavy resistance exercises and plyometric exercises within one single session, resulting in great improvement in neuromuscular adaptation. The purpose of this study was to compare the effect of CT vs. heavy resistance training (HRT) on strength and power indicators, running economy (RE), and 5-km performance in well-trained male distance runners. METHODS: Twenty-eight well-trained male distance runners (19-23 years old, VO2max:65.78 ± 4.99 ml.kg-1.min-1) performed one pre-test consisting of: maximum strength (1RM), counter movement jump (CMJ) height, peak power, a drop jump (DJ), and RE assessments, and blood lactate concentration (BLa) measurement at the speeds from 12-16 km.h-1, a 50-m sprint, and a 5-km running performance test. They were then divided into 3 groups: complex training group (CT, n = 10), that performed complex training and endurance training; heavy resistance training group (HRT, n = 9) that performed heavy strength training and endurance training; and control group (CON, n = 9) that performed strength-endurance training and endurance training. After the 8 weeks training intervention, all participants completed a post-test to investigate the training effects on the parameters measured. RESULTS: After training intervention, both the CT and HRT groups had improvements in: 1RM strength (16.88%, p < 0.001; 18.80%, p < 0.001, respectively), CMJ height (11.28%, p < 0.001; 8.96%, p < 0.001, respectively), 14 km.h-1RE (-7.68%, p < 0.001; -4.89%, p = 0.009, respectively), 50-m sprints (-2.26%, p = 0.003; -2.14%, p = 0.007, respectively) and 5-km running performance (-2.80%, p < 0.001; -2.09%, p < 0.001, respectively). The CON group did not show these improvements. All three training groups showed improvement in the 12 km.h-1RE (p ≤ 0.01). Only the CT group exhibited increases in DJ height (12.94%, p < 0.001), reactive strength index (19.99%, p < 0.001), 16 km.h-1 RE (-7.38%, p < 0.001), and a reduction of BLa concentrations at the speed of 16 km.h-1 (-40.80%, p < 0.001) between pre- and post-tests. CONCLUSION: This study demonstrated that CT can enhance 1RM strength, CMJ height, 12 and 14 km.h-1REs, 50-m sprints and 5-km running performances in well-trained male distance runners and may be superior to HRT for the development of reactive strength and 16 km.h-1RE, and reduction of BLa concentrations at speed of 16 km.h-1. Young male distance runners could integrate CT into their programs to improve the running performance.