Validity and reliability of a flywheel squat test in sport.

The aims of this study were to examine the test-retest reliability and construct validity of the flywheel (FW)-squat test. Twenty male amateur team sports athletes (mean±SD: age 23±3 years) completed one familiarization session and two testing sessions including: FW-squat test with an inertial load of 0.061 kg.m2, standing long jump (SLJ), countermovement jump (CMJ) and 5-m change of direction (COD-5m) tests, and isokinetic strength assessments of the knee extensor and flexor muscles. Test-retest reliability was assessed with intraclass correlation coefficient (ICC) and coefficient of variation (CV) of data collected. Construct validity was determined as the degree of relationships between the FW-squat test outputs and both athletic tests and isokinetic assessments scores computed with Pearson's correlation coefficients. Excellent relative (ICC=0.94-0.95) and acceptable absolute (CV=5.9%-6.8%) reliability scores were found for both concentric and eccentric power outputs collected during the FW-squat test. The same outputs showed moderate to large positive correlations with concentric and eccentric knee extensor and flexor muscle peak force values (r range: 0.465-0.566) measured during the isokinetic test. The FW-squat test is a valid and reliable test to assess lower limb performance given its correlation with isokinetic test, as well as its excellent relative and acceptable absolute reliability.

Narcissism and Intimate Partner Violence: A Systematic Review and Meta-Analysis.

This review aimed to examine the relationship between intimate partner violence (IPV) perpetration and trait narcissism, and whether the strength of this relationship differs depending on narcissism type (grandiose or vulnerable), the type of violence perpetrated, or the perpetrator's gender. Scopus, Medline, PsycInfo, and Academic Search Complete databases were searched on August 11, 2022. Studies were included if they were in English, measured IPV perpetration and trait narcissism, and examined the relationship between trait narcissism and IPV perpetration. Studies were excluded if they were review papers, conference extracts, book chapters, or if the data was not specific to trait narcissism. The AXIS tool was used to assess the quality and risk of bias of the studies. Twenty-two studies (N = 11,520 participants) were included in the random effects meta-analysis revealing a significant, weak, positive relationship between trait narcissism and IPV perpetration, r = .15. Subgroup analyses revealed physical IPV perpetration was not significantly related to trait narcissism while cyber and psychological IPV perpetration were significantly, positively, weakly related to trait narcissism. No significant difference in the strength of the relationship with IPV perpetration was found between males and females. The relationship between trait narcissism and IPV perpetration was significantly greater for vulnerable narcissism than grandiose narcissism. Overall, the quality of the included studies was high, and risk of bias was low. All measures were self-report and underreporting could be present given both narcissistic traits and IPV perpetration are considered socially undesirable. Future research examining these relationships should specify IPV and narcissism types.

Post flywheel squat vs. flywheel deadlift potentiation of lower limb isokinetic peak torques in male athletes.

The present study investigated the post-activation performance enhancement (PAPE) of isokinetic quadriceps and hamstrings torque after flywheel (FW)-squat vs. FW-deadlift in comparison to a control condition. Fifteen male athletes were enrolled in this randomised, crossover study. Each protocol consisted of 3 sets of 6 repetitions, with an inertial load of 0.029 kg.m2. Isokinetic quadriceps (knee extension) and hamstrings (knee flexion) concentric peak torque (60º/s) and hamstring eccentric peak torque (-60º/s) were measured 5 min after experimental or control conditions. A significant condition (PAPE) effect was reported (f = 4.067, p = 0.008) for isokinetic hamstrings eccentric peak torque following FW-squat and FW-deadlift, but no significant differences were found for quadriceps and hamstrings concentric peak torques. The significant difference averaged 14 Nm between FW-squat vs. control (95% CI: 2, 28; d = 0.75, moderate; p = 0.033), and 13 Nm between FW-deadlift vs. control (95% CI: 1, 25; d = 0.68, moderate; p = 0.038). This study reported that both FW-squat and FW-deadlift exercises are equivalently capable of generating PAPE of isokinetic hamstrings eccentric torque. Practitioners may use these findings to inform strength and power development during complex training sessions consisting of flywheel-based exercises prior to a sport-specific task.