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Single-leg stance requires pelvic stability, largely supported by the hip abductors. Differences in hip abductor activation between sexes and individuals with or without musculoskeletal conditions may relate to abductor weakness. However, the relationship between hip abduction strength and muscle activation during stance, and whether this is moderated by sex, remains unclear. To investigate whether maximal hip abduction strength is associated with hip abductor EMG amplitude during single-leg stance, considering sex as a moderator. Thirty-six adults (18 males, 18 females) performed an estimated 1RM side-lying hip abduction test and two 10-second single-leg stance trials. EMG amplitude of the gluteus medius (GMed) and tensor fasciae latae (TFL) was analyzed. A moderation analysis (PROCESS Model 1) was used to test the interaction between strength and sex. Hip abduction strength, sex, and their interaction explained 51% of the variance in GMed EMG amplitude (R2 = 0.51; p < 0.001). A significant strength × sex interaction were observed (p = 0.002). Females with lower strength showed greater GMed activation (p < 0.001); this was not seen in males (p = 0.24). No significant effects were found for TFL activation (R2 = 0.02; p = 0.89). Females with lower hip abduction strength demonstrate greater GMed activation during single-leg stance, suggesting a sex-specific compensatory strategy. No similar effect was observed for TFL. These findings highlight the importance of considering sex in neuromuscular assessments of pelvic stability.

Background Less-experienced runners are proposed to sustain more running related injuries (RRIs) than more-experienced runners because of differences in their gait biomechanics. However, the effects of running experience on biomechanics remain inconclusive. The objective of this systematic review was to examine the evidence concerning the influence of experience on running biomechanics and summarize the criteria used to classify running experience. A classification procedure for running experience was proposed based on the results. Methods Five common databases were searched for relevant articles following PRISMA guidelines (PROSPERO_ID CRD42022296734) and the PICO framework. Peer-reviewed research reporting a statistical effect of running experience on running gait biomechanics in adults (18–65 years) were included. Exclusion criteria were: subjects with current pathologies or symptomatic injuries; reporting running only barefoot, in minimalist shoes, during sprinting, or incline/decline running; classified experience only through performance-related measures; or did not specify running experience group definition. Risk of bias was assessed with the Downs and Black checklist. Extracted data were organized in tables and synthesized descriptively due to study heterogeneity. Results Twenty-eight studies with 916 total subjects were included. Although most studies found significance in their comparisons, no studies comparing similar gait variables found the same statistical result. Some variables compared between experience levels were examined in only one study. Experience classification criteria were inconsistent between studies; cut-offs for more-experienced ranged between 2 and 10 years and/or 15–50 km/week and cut-offs for less-experienced ranged between 0.5 and 3 years and/or 0–20 km/week. Meta-analysis was not possible due to heterogeneity among the included studies. Conclusion Effects of experience on running mechanics were inconsistent in the current literature. The lack of consistent findings may be due to the heterogeneous criteria used to classify runners into experience groups and the inconsistency of the variables investigated. Replication studies, heterogeneous study design, and longitudinal studies are needed to determine if or how running biomechanics change as runners gain experience. Heterogeneous study designs must begin with standard experience classification criteria for the effect of experience on running biomechanics to be identified. We propose an updated taxonomy to classify runners into groups considering three facets: exposure, performance, and intention. Trial registration : PROSPERO ID CRD42022296734. Registered 28 September 2022—Retrospectively registered, https://www.chictr.org.cn/bin/project/edit?pid=149714 . Key Points Current research has not consistently found statistically significant biomechanical differences between runners of different levels of experience. Heterogeneity in group classification and choice of biomechanical outcome variables likely explains the lack of differences. A new, standardized taxonomy considering three different facets of experience (exposure, performance, and intention) may help future literature synthesis.

Objective To verify if the functional capacity prior to COVID-19 infection was different between Survivor and Non-survivor older adults. Also, to verify the effect of the isolation period after COVID-19 infection on the functional capacity of the Survivors residing in nursing homes. Materials and methods Older adults residing in nursing homes were evaluated 30 days before the COVID-19 outbreak at the site for (i) general health characteristics (obtained from medical records); (ii) gait speed, handgrip strength and 30-s sit-to-stand; (iii) sarcopenia and (iv) estimated muscle mass. Comparisons were made between Survivors and Non-survivors of COVID-19. After the isolation, the Survivors performed the assessments again. Results Twenty-one (81 ± 9.3 years) participants tested positive for COVID-19 and participated in the study, 12 survivors. No difference was observed between Survivors and Non-survivors in any of the outcomes evaluated. However, a moderate effect size was observed for handgrip strength, with lower values for the Non-survivors group (− 16%; d  = 0.53). The isolation period reduced the number of sit-to-stand repetitions with moderate effect size in the Survivors ( p  = 0.046, g av  = 0.66). Conclusion Although the null hypothesis analysis did not find significant differences between the groups, the effect size suggests that older adults residing in nursing homes who died from COVID-19 had lower handgrip strength. In the survivors, the isolation period after COVID-19 infection only negatively impacted the sit-to-stand performance.

Purpose The aim of this study was to compare the effects of 8 weeks of resistance training (RT) and high-intensity interval training (HIIT) on muscle strength, muscle power and cardiorespiratory responses in trained young men. Methods Twenty-two men [RT ( n  = 11); HIIT ( n  = 11)] performed 8 weeks of training, with frequency of 2 times per week. RT group performed 10 sets × 10–12 RM of Leg-press exercise, while HIIT group performed 10 sets of running × 60 s at 85–95% of maximal heart rate. Both groups performed 60 s of passive rest between sets. Maximal strength (one-repetition maximum [1RM] of Leg Press and Knee Extension), jump height (single-leg countermovement jump) and cardiorespiratory responses during Conconi Test (predicted VO2peak and heart rate at maximal and at deflection point) were evaluated at baseline and after training program. Results 1RM of Leg Press increased in both training groups ( p  < 0.001), with higher gains in the RT group (RT = 32.2%, HIIT = 9.5%; p  = 0.036; d = 1.86), 1RM of Knee Extension did not improve for either group ( p  = 0.065). Only the HIIT group improved jump height (RT = − 1.5%, HIIT = 14.2%; p  = 0.002; d  = 1.52) and cardiorespiratory capacity (RT = − 1.1%, HIIT = 3.2%; p  = 0.006; d  = 1.27). Conclusion Despite RT group promoting higher strength gains, HIIT is also effective for improving strength, jump height and cardiorespiratory capacity, and it presents as a possible alternative for people who seek improvements in health variables. Trial registration This study was registered in Brazilian Clinical Trials Registry (registration number RBR-7n8y9ky) on Mar 09th 2021 (retrospectively registered).

A pesquisa indaga sobre os caminhos para viabilizar uma construção conceitual acerca da materialidade e da institucionalidade da informação, fenômenos concernentes à transformação do objeto em documento. Objetiva (a) fundamentar e (b) sintetizar caminhos para a investigação dos fenômenos; e (c) edificar um quadro de articulações conceituais sobre a informação materializada e institucionalizada como documento. Para tanto, lançou mão de revisão de literatura, estabelecendo vínculos interdisciplinares, epistemológicos e políticos, tocantes às ciências da documentação e da informação. A pesquisa empregou, ademais, elementos teórico-metodológicos de Imre Lakatos como subsídio para a proposição de um programa de investigação, estruturante para o ordenamento e a articulação das escolhas teórico-metodológicas. Contando com contribuições de obras de Habermas, Foucault, Weber e Bourdieu, tais escolhas perpassam fundamentações de “pretensões de validade, práticas discursivas e horizontes políticos”, de “materialidade sociocultural, simbólico-burocrática e políticas de informação”, do “objeto-suporte e materialidade de ações e práticas informacionais” e dos “contextos epistemológico e políticos: materialidade/institucionalidade/representação”. Os caminhos e as articulações conceituais culminaram no núcleo do programa, a partir do qual se pode observar que o documento é um valor informacional que se atribui ao objeto, ou seja, é o produto da significação ou da função atribuída a uma coisa em determinada institucionalidade. Assim, a materialidade do documento transcende a fisicalidade da informação num suporte, à medida que todo documento: (a) representa algo e pode ser representado; (b) é uma expressão simbólica de poder/saber. Por fim, o documento é um produto de ações e práticas sociais, sendo definido por institucionalidades da informação as quais têm o acesso e as condições de atuação condicionadas por perspectivas de materialidade.

Purpose Fatigue-induced hip-abductor weakness may exacerbate lower-limb misalignments during different dynamic single-leg tasks. We sought to evaluate the effects of fatigue and task on lower limb kinematics and muscle activation and to find associations between measurements obtained in two tasks. Methods One-group pretest–posttest design. Seventeen healthy adults (9 W) performed the single-leg squat (SL SQUAT ) and the single-leg hop (SL HOP ) before and after a hip-abduction fatigue protocol. Hip adduction, knee frontal plane projection angle (knee FPPA) and heel inversion displacement were measured during the eccentric phase of the SL SQUAT and the SL HOP , as well as activation of the gluteus medius (GMed), tensor fascia latae (TFL), peroneus longus (PER) and tibialis anterior (TA). Moments and tasks were compared using a repeated-measures two-way ANOVA. Correlation between tasks was evaluated using Spearman’s correlation. Results No differences in kinematics or activation were found between moments. Hip-adduction displacement ( P  = 0.005), GMed ( P  = 0.008) and PER ( P  = 0.037) activation were higher during SL SQUAT , while TA activation was higher during SL HOP ( P  < 0.001). No differences were found between tasks in knee FPPA and heel inversion. Hip-adduction and knee FPPA were not correlated between tasks, while ankle inversion displacement was positively correlated ( r s  = 0.524–0.746). Conclusion Different characteristics of SL SQUAT (slower and deeper) seem to have led to increased hip adduction displacement, GMed, and PER activation and decreased TA activation, likely due to higher balance requirements. However, hip-abductor fatigue didn’t influence lower-limb alignment during the tasks. Finally, evaluations should be performed with different single-leg tasks since they don’t give the same lower-limb alignment information.

Purpose CrossFit® (CF) is a high-intensity training method with a large number of practitioners, having an injury prevalence similar to other sports. Although excessive dynamic knee valgus is related to several injuries and associated with the trunk muscles’ endurance and dorsiflexion range of motion (DF-ROM), no study has evaluated these parameters in CF practitioners. The aim of the study was to investigate the association between lower limb alignment during the step-down test, DF-ROM and lateral trunk muscle endurance in CrossFit® (CF) practitioners. Methods Forty-two CF practitioners performed the following tests on both limbs: (i) DF-ROM with the weight-bearing lunge test; (ii) knee frontal plane projection angle (FPPA) and hip adduction (hip ADD) ankle during the forward step-down test; (iii) trunk lateral flexors’ endurance with the side plank test. Results No significant associations were found between knee FPPA and DF-ROM in both limbs (preferred: r  = 0.192; p  = 0.230; non-preferred: r  = 0.089; p  = 0.581) or side plank time (preferred: r  = 0.086; p  = 0.594; non-preferred: r  = 0.248; p  = 0.117). Moreover, no significant associations were found between hip ADD and DF-ROM in both limbs (preferred: r  = 0.005; p  = 0.975; non-preferred: r  = 0.175; p  = 0.275) or side plank time (preferred : r  = – 0.134; p  = 0.403; non-preferred: r  = 0. 171; p  = 0.284). Conclusion Lateral trunk flexors’ endurance and ankle dorsiflexion range of motion are not associated with hip and knee kinematics during the forward step-down test in CrossFit®.