The effect of the overload principle in motor skill acquisition is unclear. Hence, the present study examined the effect of the overload principle in general, and in particular how the overload principle can be used to increase transferability to nontrained balance tasks with a high level of similarity at different levels of difficulty. A total of 24 participants were randomly assigned to two training groups: (1) low-difficulty training group and (2) high-difficulty training group. Both training groups completed five training sessions consisting of 25 trials over three weeks and only the level of difficulty of the balance board differed. Both the low and high-difficulty training groups had a significant improvement in balance performance in the specific trained conditions, which supports the specificity principle. Most interestingly, only the high-difficulty training group showed significant positive transfer to balance tasks with lower levels of difficulty. The low difficulty training group did not show significant positive transfer to balance tasks with higher levels of difficulty. These findings support the effect of the overload principle. In conclusion, the present findings demonstrate the superior effect of task-specific balance training, and, most interestingly, the study revealed that training with overload at higher levels of difficulty enhances transferability to similar tasks performed at lower difficulty levels.

Mechanical properties of the deep muscle fascia are important in myofascial force transmission and injury; however, its investigation by shear wave elastography (SWE) in the literature is minimal. Regional differences in biarticular muscle stiffness have implications in mechanism of injury. To determine region-specific differences in rectus femoris (RF) fascia and muscle stiffness, 20 healthy participants completed two visits in which RF fascia (FAS) and superficial (SUP) and deep (DEEP) muscle regions were assessed by SWE in three muscle regions (proximal - PROX, medial - MED and distal - DIST) and at three muscle lengths (relaxed - REL, neutral - NEU and passively stretched - PAST). DEEP was consistently stiffer than SUP muscle tissue (all p<0.01) in all conditions and regions, except for REL PROX. Regional differences in SWV in all of FAS, SUP and DEEP were dependent upon local strain. Hip extension increased proximal tissue stiffness above medial and distal regions (all p<0.001) and conditions of hip flexion (p<0.001, p=0.004 and p=0.002, respectively). Similarly, knee flexion increased distal tissue stiffness above conditions of knee extension (all p<0.001). Stretching the muscle by hip extension and knee flexion (PAST) removed differences between the regions in FAS, SUP and DEEP and increased medial SWV above REL and NEU (all p<0.001). These results provide novel insight into regional differences in biarticular muscle and fascial tissue stiffness, implying that local strain increases stiffness in the adjacent region. These findings may have implications in force generation and region-specific mechanisms of injury.

The aim of this study was to evaluate whether the highest power output at which the predominant energy contribution is derived from the aerobic system (aerobic limit power: ALP), as estimated using maximal accumulated O2 deficit (MAOD) method, corresponds to the upper boundary of the severe intensity exercise domain. Thirteen males completed: (i) a ramp incremental exercise test, (ii) four submaximal constant power exercise tests, and (iii) 6-7 maximal and at least one supramaximal constant power exercise tests. The upper boundary of the severe intensity exercise domain was estimated based on the linear relationship between the time to achieve O2max and the time to task failure (PUPPERBOUND). The ALP was estimated by MAOD method, i.e. based on the difference between the predicted O2 demand derived from a linear regression line from submaximal exercise tests and the accumulated O2 uptake calculated by integrated O2 data. The highest power output at which the aerobic energy contribution rate was still predominant (i.e., 50%+) was defined as the ALP. Based on the principal results, ALP estimated by MAOD was not significantly different from the PUPPERBOUND (390±58 vs. 387±61; p=0.16; effect size: 0.42) and they were closely aligned (r: 0.99; bias: 3±7W; standard error of estimation: 7W; limits of agreement: -11-17W). Consequently, ALP, as derived from the MAOD method, provides a non-invasive alternative to accurately determine the PUPPERBOUND with less physiological stress.

Postmenopausal obesity is an important public health concern, accompanied by increased systemic inflammation that heightens the risk of liver disease. Exercise improved both inflammatory and hepatic function. Moderate-intensity intermittent-walking training (MIWT) is considered a feasible approach for postmenopausal women with obesity. This study aimed to investigate whether MIWT could reduce the risk by modulating hepatic enzymes and selected inflammatory markers. Thirty-six sedentary postmenopausal women with obesity (mean age 55.7±3.5years; mean weight: 86.9±12.2kg; mean BMI: 34.0±5.0kg/m2) were randomly assigned to a training group (TG, n=18) or a control group (CG, n=18). The TG completed a 10-week MIWT protocol (4 sessions/week, ∼85min/session), involving repeated walking intervals at 60%-80% of the 6MWT distance with active recovery. As a secondary objective, changes in body composition and aerobic capacity were also assessed. Significant improvements were observed in the TG group in liver enzymes alanine-transaminase (ALT), (p=0.002, d=0.29), aspartate-transaminase (AST) (p=0.013, d=0.29), gamma-glutamyl-transferase (GGT) (p=0.036, d=0.25), total bilirubin (p=0.009, d=0.13), and C-reactive-protein (CRP) (p=0.007, d=0.49). Additionally, significant reductions were found in body mass (p<0.001), BMI (p<0.001), body fat (p=0.001), and waist circumference (p<0.001), along with increased aerobic capacity (p=0.031). These findings indicate that MIWT is a feasible and effective intervention for inducing favorable changes in liver-related biochemical markers and systemic inflammation, with additional benefits for body composition and aerobic fitness in postmenopausal women with obesity.

This study aimed to investigate the effect of training background on neuromuscular responses to submaximal isometric fatiguing contraction. Eleven strength-trained (ST) and 11 endurance-trained (ET) males performed maximal voluntary isometric knee extension contractions (MVIC) and a torque steadiness task at 20% MVIC before and immediately after a submaximal isometric contraction at 30% MVIC performed until task failure. High-density surface EMG was recorded from the vastus lateralis muscle. The EMG root mean square (RMS) amplitude, median frequency (MDF) and muscle fibre conduction velocity (MFCV) were estimated. There was no significant difference in time-to-failure (88.2±34.3 vs. 157.6±126.1s) or post-fatigue MVIC reduction (19.4% vs. 22.5%) between the ST and ET groups. However, post-fatigue EMG MDF decreased by 10.8% in ST (p<0.05), but remained unchanged in ET. Furthermore, only the ET group showed a significant decrease in torque steadiness (p<0.05) and an increase in physiological tremor (8-12Hz; p<0.01) during the post-fatigue steadiness task. Throughout the fatiguing task, the mixed effects model revealed decreases in MFCV (p<0.01) and MDF% (p<0.001) in ST, with no differences observed in the ET group. EMG RMS amplitude increased similarly in both groups during the fatiguing contraction (p<0.001). Fatiguing exercise induced comparable reductions in MVIC in ST and ET males. However, fatigue differentially affected the neuromuscular strategies adopted by each group when generating maximal strength and maintaining submaximal torque output, possibly reflecting differences in muscle fibre distribution between the two groups.

Bullying remains one of the major challenges in education, and physical education (PE) can play a key role in its prevention while promoting students' socio-emotional and motivational development. This study examined the effects of the Prevention Bullying in Physical Education (PREBULLPE) programme and cooperative learning pedagogical practice on social and emotional competencies and student motivation in PE classes. The evaluation of both educational programmes was conducted with a total of 330 primary and secondary school students (aged 11-16 years), divided into three groups: the control group (CG, n=116, M=13.24 and SD=1.92), the cooperative learning experimental group (CL, n=104, M=12.98 and SD=1.79), and the PREBULLPE experimental group (PB, n=110, M=13.92 and SD=1.92). A quasi-experimental design was used, with two time point measurements conducted. The Social and Emotional Competencies Questionnaire (SEC-Q) and the Motivation Questionnaire in PE (MQPE) were used. A paired-samples t-test was applied to evaluate within-group differences, and an analysis of covariance (ANCOVA) was performed to detect possible between-group differences, assuming baseline values as covariates. Results showed that social and emotional competencies improved only with the PREBULLPE programme, although there were no significant differences among groups. Autonomous motivation in PE classes improved in both programmes, showing significant differences from the control group. In conclusion, PREBULLPE is effective in improving socio-emotional competencies and autonomous motivation in PE. Cooperative learning, although not enhancing these competencies, contributes to increasing motivation. These findings highlight the need to implement specific PE programmes to prevent bullying and foster students' holistic development.

Limited data exist describing how professional footballers meet their energy requirements during pre-season, a phase characterised by increased training volume and a progressive shift from general conditioning to football-specific preparation. This study quantified total, resting, and activity energy expenditure (AEE), diet-induced thermogenesis, water turnover, and dietary intake in six professional male soccer players (age: 25±1year; height: 182.5±10.1cm; body mass: 77.8±8.2kg). Players were studied across 14 consecutive days, representing training-only and training-plus-match microcycles. Total energy expenditure (TEE) was measured using doubly labelled water, resting energy expenditure (REE) by indirect calorimetry and dietary intake using the remote food photography method. Fourteen-day mean TEE, REE, AEE and water turnover were 13.25±1.31MJ⋅day-1, 7.96±0.89MJ⋅day-1, 4.20±1.03MJ⋅day-1, 5.16±0.66L⋅day-1, respectively. Physical activity level was 1.67±0.16 AU. Energy, carbohydrate, protein, and fat intakes were 10.95±1.52MJ⋅day-1, 2.8±0.6g⋅kg-1⋅day-1, 2.2±0.4g⋅kg-1⋅day-1, and 1.5±0.4g⋅kg-1⋅day-1, respectively. Total energy expenditure was not significantly different between training-only and training-plus-match microcycles (+1.89 ± 1.98 MJ⋅day-1; ES=0.95±1.08; p=0.100). No significant differences were observed in energy or macronutrient intake across weekly microcycles (p>0.068) or between days (p>0.144). Players did not achieve energy balance or align dietary intake with day-to-day training demands, suggesting limited nutrition periodisation during pre-season. These findings highlight the need for practitioners to implement strategies supporting fuelling, recovery and adaptation during this critical phase.

Ultrasound-based anatomical cross-sectional area (US-ACSA) measurement using extended-field-of-view (EFOV) imaging offers a practical alternative to magnetic resonance imaging (MRI-ASCA) measurements. Although its reliability and validity have previously been assessed, previous studies have focused only on a single or limited number of muscles with little attention to effects of muscle size and sex. This study was conducted in ten lower limb muscles of varying sizes in males and females in order to assess the reliability and validity of US-ACSA measurements using MRI as the gold standard method. Twelve males and twelve females participated in this study. US- and MRI-ACSA were measured twice, one day apart. Reliability was assessed using intraclass correlation coefficients (ICC2,3), standard error of measurement (SEM) and minimal detectable change (MDC). Validity was examined using Pearson product-moment correlation and Bland-Altman analysis. A linear model was used to evaluate the effects of muscle size and sex. ICC2,3, SEM and MDC ranged from 0.992% to 0.999%, 0.50%-1.90% and 1.25%-5.36% for US-ACSA and from 0.952% to 0.998%, 0.90%-4.76% and 2.51%-13.19% for MRI-ACSA. US-ACSA showed strong correlations with MRI-ACSA (r=0.73-0.95). A systematic underestimation of MRI values (relative bias: -11.5% to -23.7%) was identified, with no systematic effect of muscle size or sex. These findings suggest that US-ACSA measurements of lower limb muscles are highly reliable regardless of muscle size and sex. However, due to the large systematic bias, US- and MRI-based ACSAs measurements are not interchangeable.

Blood flow restriction (BFR) training elicits cardiovascular and muscular adaptations across exercise modalities, but its potential to enhance performance in sport-specific tasks such as climbing remains unclear. This investigation focused on sport climbing, examining the effects of incorporating BFR training on performance and hemodynamic adaptation. Rock climbers (n=25); age 26.3±4.1, weight 66.1±8.5kg, participated in a 6-week intervention, training 2-3x per week with 3 sets of climbing to voluntary failure lasting 106±28s across all exercise sets. A BFR and non-BFR (NBFR) group were included. The BFR group performed BFR hangboard exercise (cuff pressure 200mmHg), directly following each climbing set. Climbing performance was assessed on a standardized route with additional finger strength and endurance tests. A second test visit included hemodynamic measures using near infrared spectroscopy while recording blood pressure and heart rate during intermittent handgrip contractions (10s:3s duty cycle for 14 cycles) and post exercise circulatory occlusion (PECO). Climbing performance in the BFR and NBFR groups increased from 126s±26-169s±49 and 127s±43-162s±63 respectively p=0.0001. Finger strength decreased in the BFR group while there were no changes in finger endurance in either group. For hemodynamic variables, only total hemoglobin showed an increase during rest phases between isometric contractions independent of group (p=0.0004). Training had no effect on the PECO responses but did show decreases in blood pressure, but not heart rate, during the intermittent isometric handgrip contractions. Compared to traditional training alone, BFR training may have limited practical utility for augmenting small muscle mass strength-endurance performance in climbing.