Applied Sciences

Background: Age-related differences in neuromuscular coordination during multi-joint tasks are reported, but phase-specific evidence during maximal sprinting is limited. Aim: The aim of this study was to investigate phase-specific age differences in agonist–antagonist coordination of the biarticular thigh muscles during 50 m sprinting. Methods: Thirty-eight healthy trained track athletes (Adults: n = 21, age = 23.32 ± 2.98 years; Adolescents: n = 17, age = 13.65 ± 0.76 years) performed maximal 50 m sprints over force plates. Bilateral rectus femoris (RF) and biceps femoris (BF) sEMG and ground reaction forces were recorded; each stride was segmented into seven phases, and an RF–BF co-contraction index (CCI) was calculated per phase. Between-group differences in phase mean CCI were tested (α = 0.05) and quantified with Hedges’ g. Speed- and frequency-dependent modulation of CCI was evaluated using linear mixed-effects models (LME; random intercepts for participant) with Frequency × Group and Speed × Group interaction terms; ordinary least squares (OLS) fits on stride cycle-level group means were descriptive. Linear and single-breakpoint segmented models were compared using the corrected Akaike information criterion (AICc) and Akaike weights. Results: Adolescents showed higher CCI in contact (right: Adults 0.09 ± 0.05 vs. Adolescents 0.13 ± 0.07, g = 0.68; left: Adults 0.08 ± 0.04 vs. Adolescents 0.12 ± 0.06, g = 0.84) and propulsive phases (right: Adults 0.08 ± 0.05 vs. Adolescents 0.13 ± 0.08, g = 0.68; left: Adults 0.07 ± 0.04 vs. Adolescents 0.12 ± 0.07, g = 0.84; p < 0.05 for both legs in both phases). LME identified Frequency × Group interactions in the stride cycle (ΔSlope = 0.10, p < 0.001) and late swing (ΔSlope = 0.12, p < 0.05) and a Speed × Group interaction in mid swing (ΔSlope = 0.01, p < 0.05). Mid swing showed a positive CCI–speed/frequency relationship in both groups, whereas across most other phases Adults downregulated CCI as speed/frequency increased while Adolescents tended to increase CCI. Model selection supported phase-dependent single-breakpoint patterns, with breakpoints around 2.19–2.21 Hz and 6.11–9.51 m·s⁻¹ in Adults and around 2.11 Hz and 7.13–7.59 m·s⁻¹ in Adolescents. Conclusions: Maximal sprinting revealed phase-specific age differences in BF–RF co-contraction and its scaling with speed/frequency, which may help guide age-informed monitoring and training considerations in developing athletes.

This study evaluates perceived facial aesthetics across different age groups (18–29 years, 30–55 years, >55 years) through a questionnaire incorporating modified profile photographs of a male and a female subject. These images were adjusted based on the position of the central incisor and the Barcelona line described by Hernández-Alfaro. Statistical analyses were primarily conducted by age group and secondarily by sex and prior studies, using the Shapiro–Wilk, Mann–Whitney U and Kruskal–Wallis tests. All analyses were performed with a significance level set at p < 0.05. Significant differences were observed in the evaluation of facial aesthetics across age groups, as well as between sexes and participants with varying level of education. Younger individuals showed greater acceptance of protrusive profiles, while women and participants with higher educational attainment tended to be more critical in their evaluations.

Background: Assessment of body-related perceptual disturbances is important in adolescent girls. Objective: This pilot exploratory study investigates distortion and dissatisfaction related to trunk symmetry perception in a non-clinical sample of female adolescents using Scoliosis 3D, a virtual reality-based tool. Methods: Entry criteria were females aged 12–18 years with no scoliosis or other spinal deformities confirmed by clinical examination. Thirty participants (mean age 15.03 ± 1.30 years; mean Body Mass Index [BMI] 22.88 ± 4.68 kg/m²) were evaluated using the virtual reality application, the Body Esteem Scale, and the Strengths and Difficulties Questionnaire–25. Virtual reality-based indicators were derived from participants’ selections of perceived and desired trunk symmetry and their comparison with actual clinically assessed trunk alignment. Results: The difference between estimated current and actual body shape (trunk symmetry distortion) was significant (p = 0.001), as was the difference between estimated current and desired body shape (trunk symmetry dissatisfaction, p = 0.001). Conclusions: These findings provide preliminary evidence supporting the feasibility of Scoliosis 3D for exploratory assessment of perceptual discrepancies related to trunk symmetry in healthy adolescent females. Participants frequently misperceived their current trunk symmetry and experienced dissatisfaction with it, with higher distortion and dissatisfaction associated with a less positive attitude toward physical condition.