ABSTRACT:Pinto, MP, Neiva, HP, Sampaio, T, Oliveira, JP, Barbosa, TM, Marinho, DA, and Morais, JE. Understanding differences in swimming velocity and propulsive force in the butterfly stroke: A comparison between male and female butterfly swimmers through discrete and continuous variables. J Strength Cond Res XX(X): 000-000, 2026-The aim of this study was to verify differences in swimming velocity and propulsive force (PF) between male and female swimmers in the butterfly stroke based on discrete variables and Statistical Parametric Mapping (SPM-continuous variables). The sample comprised 20 young national-level swimmers (10 boys with 17.9 ± 1.2 years and 10 girls with 15.5 ± 1.4 years). Swimming velocity, intracyclic variation of swimming velocity, stroke frequency, stroke length, stroke index, and PF were measured as discrete variables. Swimming velocity and PF were also measured as continuous variables with SPM. As a discrete variable, swimming velocity presented significant differences between sexes with very large effect sizes (p < 0.001, d = 2.46). The average PF also presented significant differences between sexes with very large effect sizes (p < 0.001, d = 2.01). Male swimmers were faster and generated greater PF than female swimmers. As for SPM, velocity presented significant differences between sexes (t = 3.355, p < 0.001) between ∼31 and ∼56% of the stroke cycle. This corresponds mainly to the end of the pull and most of the push phase. PF followed the same trend, with differences in the same phase of the time series. SPM allowed for identification where, within the stroke cycle, differences between sexes occurred in velocity and PF. Being in the same phase of the time series highlights the existing velocity-PF relationship. SPM can allow researchers and coaches to pinpoint the exact moments within the stroke cycle where differences between swimmers may occur.

Sustained high respiratory load is recognised as a functional-safety issue in high-demand environments, yet remains underrepresented in occupational health. Constrained breathing, high inspiratory work and limited recovery may accelerate inspiratory muscle fatigue, increase perceptual strain and impair task execution. Inspiratory muscle training (IMT) has been proposed as a preventive strategy, but its effectiveness appears to depend on dose governance. Objectives: To critically appraise randomised controlled trials (RCTs) of IMT in competitive swimmers as a high-demand model, focusing on inspiratory muscle strength, functional capacity under respiratory load, pulmonary function and perceived exertion, and examine how dose governance influences safety-relevant outcomes. Methodology: A critical review of RCTs used a PICOT framework. Methodological quality was assessed using Oxford Levels of Evidence, the Physiotherapy Evidence Database (PEDro) scale and the Cochrane Risk of Bias 2.0 (RoB 2.0) tool. Results: Three RCTs were included (Oxford level 1b; PEDro 6–8/10; RoB 2.0: some concerns). Supervised IMT with progressive loading and documented adherence produced consistent improvements in inspiratory strength and functional-capacity markers, whereas weak dose verification was associated with absent or equivocal effects despite longer programme duration. Conclusions: IMT may support respiratory-load regulation and functional safety only under explicit and verifiable dose-governance conditions; duration alone is insufficient.

The aim of this study was to compare swimming velocity, intra-cyclic variation of swimming velocity, jerk cost, and the resultant mechanical impulse in young swimmers of both sexes and by levels in the front crawl stroke. The sample included 60 young swimmers (30 boys aged 13.03 ± 0.99 years, and 30 girls aged 12.43 ± 0.90 years). Each sex group was split into two subgroups (best vs. poorest performers) of 15 swimmers each. Swimming velocity, during maximal 25 m efforts, revealed a 'sex' and 'level' main effect and interaction (p < 0.001). A 'sex' X 'level' interaction (F = 5.18, p = 0.027, η2 = 0.08) with a minimum effect size was noted for the jerk cost. Both the propulsive and resistive/braking impulses presented main effects for 'level' (positive: F = 15.65, p < 0.001, η2 = 0.22; negative: F = 12.41, p < 0.001, η2 = 0.18) with a minimum effect size. Overall, the jerk cost, as well as the intra-cyclic variation in swimming velocity as indicators of motion 'smoothness', did not significantly discriminate between the best and the poorest performers in maximal 25 m efforts. Conversely, the mechanical resultant impulse did. This indicates that the mechanical resultant impulse is a strong determinant of swimming velocity in young swimmers, at least in maximal 25 m efforts.

This study aimed to evaluate the effects of caffeine (CAF) and carbohydrate (CHO) mouth-rinsing on soccer passing performance and psychophysiological responses using the Loughborough Soccer Passing Test (LSPT). Twenty-five well-trained male youth soccer players (age: 16.6 ± 0.5 years) participated in a randomized, double-blind, crossover trial involving three experimental conditions: CAFF-MR (1.2

ABSTRACT:Santos, CC, Marinho, DA, and Costa, MJ. Effect of biological maturation on shoulder rotator strength and performance after a 6-week summer break in young male swimmers. J Strength Cond Res XX(X): 000-000, 2026-This study aimed to analyze the effects of biological maturation on shoulder rotator strength and performance after a 6-week summer break in young male competitive swimmers. Twelve young swimmers were divided into pre- and mid-peak height velocity (PHV) groups. Anthropometric variables (body mass, stature, and arm span) and dryland shoulder rotator cuff strength (internal rotation; external rotation, strength balance; internal rotation/external rotation ratio) of both limbs were measured in pre- and post-test (6-week apart), alongside 25 m front crawl performance (time, T25; speed, s25) and kinematics (stroke rate; stroke length; stroke index, SI). ANOVA (level of significance p ≤ 0.05) revealed between-group (maturity offset [MO]) effects for body mass, stature, arm span, T25, s25, stroke length, and SI, indicating that mid-PHV swimmers had larger anthropometrics, strength, and stroke efficiency. Time effects were observed only for SI, while no interaction MO*time was observed. A natural growth was experienced by both MO groups, being more evident in pre-PHV swimmers. Mid-PHV swimmers showed improvements in shoulder rotator strength balance, whereas pre-PHV swimmers showed greater muscular imbalances after the summer break. Performance and kinematic variables remained stable or even slightly improved. A 6-week summer break did not impair shoulder rotator strength or swimming performance in either MO group. Thus, the interpretation of (de)training effects according to each swimmer's MO could become standard practice among swimming coaches.

Objectives: This study aimed to examine the effects of three different warm-up protocols on performance, physiological, and perceptual responses in high-level water polo players. Methods: Ten international-level athletes (Tier 4; mean ± SD: age 22.4 ± 3.53 years; height 1.78 ± 0.06 m; body mass 75.83 ± 6.44 kg) completed three experimental conditions in a randomized, counterbalanced design: dryland, in-water, and combined warm-up. Following each warm-up condition, participants performed the Water Polo Intermittent Shuttle Test (WIST), while performance (distance covered and average speed), blood lactate concentration ([La-]), heart rate (HR), tympanic temperature, and rating of perceived exertion (RPE) were assessed. Statistical significance was set at p ≤ 0.05. Results: Players covered greater distances following the in-water (331.5 ± 151.24 m) and combined (358.5 ± 134.06 m) warm-ups compared to dryland (226.5 ± 129.51 m; p < 0.01; ES = 2.00 and 1.53, respectively), with no significant differences between in-water and combined conditions (p = 0.381; ES = 0.29). Physiological responses following the WIST were largely similar between conditions, although [La-] was higher in the dryland condition (12.46 ± 4.46 mmol·L-1) compared to the combined condition at 10 min post-exercise (8.66 ± 2.47 mmol·L-1; p = 0.03; ES = 0.80). No differences were found for HR, tympanic temperature, or RPE. Conclusions: These findings suggest that warm-up protocols including an in-water component are more effective than dryland-only routines for optimizing intermittent performance in water polo players. However, combining dryland and in-water exercises does not appear to provide additional benefits compared to in-water warm-up alone.

Resistance training (RT) is commonly used to enhance neuromuscular performance and sprint swimming outcomes. However, the optimal relative load for elite junior swimmers remains unclear. In particular, little is known about whether very low relative loads can elicit meaningful adaptations while minimizing neuromuscular fatigue in athletes exposed to high concurrent training demands. Therefore, the aim of this study was to compare the effects of two land-based RT programs differing only in relative load intensity (40–50% vs. 55–65% 1RM), performed with maximal intended concentric velocity, on strength, jumping ability, and 50 m freestyle swimming performance in elite junior swimmers. Eighteen elite junior swimmers (15.6 ± 0.9 years) from a national high-performance program were randomly assigned to a low-load (40–50% 1RM; n = 9) or moderate-load (55–65% 1RM; n = 9) group. Both groups completed an 8-week RT program (2 sessions·week−1) with identical exercise selection, volume, execution velocity, and in-water training load. Neuromuscular performance (countermovement jump, squat, bench press, and pull-up strength) and swimming performance (50 m freestyle from the starting block and in-water start) were assessed pre- and post-intervention. Both RT protocols improved squat and bench press strength and 50 m freestyle performance, whereas significant improvements in countermovement jump, pull-up strength, and maximal pull-up repetitions were observed only in the low-load group. Significant group × time interactions were found for countermovement jump, maximal number of pull-up repetitions, and 50 m freestyle performance from the starting block, indicating more favorable changes over time in the low-load group. In conclusion, both low- and moderate-load high-velocity RT improved neuromuscular and 50 m freestyle performance outcomes in elite junior swimmers. However, the low-load RT (40–50% 1RM) appeared to provide additional benefits in specific outcomes (i.e., jumping, pull-ups, and 50 m performance from the starting block). These findings suggest that relatively low loads may be a practical alternative to moderate-load RT in high-volume swimming training environments.

Featured Application In competition, swimmers may experience prolonged transition phases, which can contribute to a loss of body temperature and reduced readiness before performance. In the present study, a dryland explosive re-warm-up protocol was associated with faster 100 m freestyle performance than the control condition. Because this strategy is easy to implement in different pool settings, it may represent a practical option for sprint swimmers during competition. By contrast, the in-water, race-pace strategy did not significantly improve the main performance outcomes under the present conditions, although it may deserve further investigation in longer-distance events.Abstract The transition phase often causes athletes to lose the benefits of warm-up, so this study aimed to assess the effects of two re-warm-up protocols and a control condition without re-warm-up on 100 m freestyle performance and the kinematic variables (stroke length (SL), stroke rate (SR), and stroke index (SI)), subjective perception of effort (RPE), and physiological variables (heart rate (HR), temperature (T), and blood lactate concentration (La-)). Twenty competitive-level swimmers completed a dryland and water warm-up, followed by a 30 min transition phase and a 100 m freestyle simulation. Over 30 min, each swimmer randomly performed one of three re-warm-up protocols: control (remaining seated), dryland (explosive exercises), and water (race-pace series). The three experimental re-warm-up protocols affected 100 m freestyle performance (p = 0.019; eta 2p = 0.189). Post hoc comparisons showed that dryland was faster than control (-0.68%, p = 0.009), whereas no significant difference was observed between water and control (-0.52%, p = 0.234). No significant differences were observed between conditions for SR, SL, RPE, or La-, whereas peak HR was lower in the control. Although water did not significantly improve performance, swimmers reported more favourable sensations during the trial. In conclusion, the dryland protocol significantly improved 100 m freestyle performance, whereas the water protocol did not produce significant performance benefits under the present conditions.

The aim of this study was to analyse lap performance stability, stroke kinematic variables in the clean swimming phase and turn performance in the finals of the four 200 m short course (SCM) events (freestyle, backstroke, breaststroke, and butterfly). The sample included thirty-two elite female swimmers who competed in the 200 m finals at the 2019 LEN European Short Course Championships in Glasgow. Lap times, stroke kinematics, and turns were analysed using two approaches: (i) official lap time comparison (50 m), and; (ii) comparison of consecutive segments (25 m). Based on the official lap time comparison, performance significantly decreased over time (p < 0.001) with strong effect sizes in all strokes (η 2 between 0.89 and 0.96). Pairwise comparisons between consecutive 25 m segments were not significant. Turn time increased in all four strokes with strong effect sizes (p < 0.001; η 2 between 0.71 and 0.84). The start contributed ∼6% and turns ∼52% of the total race time. These findings highlight that traditional pacing analysis based on official splits may lead to misleading interpretations of performance in SCM events. Analysing 25 m segments provides a more accurate representation of race dynamics and contributes to a clearer understanding of pacing stability in short-course swimming.

Effectively implementing velocity-monitored resistance training (RT) requires selecting appropriate methodologies, particularly in older adults. The current study compares the differences in repetition velocity patterns with two different starting execution techniques - eccentric-concentric vs. concentric-only - during RT sets in the leg press (LP) and chest press (CP) in older adults. Eighteen participants (67

Studies about drag in swimming usually report or put the focus on its absolute value. However, it is being claimed that the drag coefficient better represents the hydrodynamic profile of a swimmer. Drag is strongly dependent on speed. Thus, increases in speed will lead to increases in drag. This could lead to misleading interpretations since drag is the water resistance that makes the swimmers’ displacement difficult. Conversely, the drag coefficient is less dependent on speed, which can be seen as a more appropriate measure of the swimmers’ hydrodynamic profile. This study used a complete experimental methodology (experimental and cross-sectional study) to determine the resistive forces in crawl swimming at the same speed (i.e., 1.00, 1.05, 1.10 m/s, etc.). In 10 proficient non-competitive adult swimmers (seven men and three women), the drag coefficient (CD ) was compared and the difference between using the technical drag index (TDI) with drag (D, passive or active) or with its respective CD 's. Measurements of active drag (DA ), passive drag (DP ) and CD (CDA and CDP ) were carried out. The TDI was calculated as a measure of swimming efficiency and the frontal surface area (FSA) obtained in active conditions. The active FSA was 20.73 ± 5.56% greater than the passive FSA (large effect size), the propulsion was 58.29 ± 69.61% greater than drag and CDA was 24.60 ± 46.55% greater than CDP (moderate effect size). TDI was significantly lower, but with a small effect size when measured with CD values compared to drag. TDID vs TDICD revealed strong agreement (> 80% of plots were within IC95). This study concludes that proficient swimmers presented a CDA greater than the CDP, but with strong agreement between them, probably due to FSA during active conditions. CD data appears to be a more absolute indicator of drag than TDI.

This study aimed to compare the aerodynamics of a shoulder amputee cyclist through computational fluid dynamics (CFD) and mathematical models. The geometry of the cyclist-bicycle system was collected by a Sense 3D scanner. The boundaries around the bicycle-cyclist system were defined on Ansys Workbench software. The velocities were set between 1 and 13 m/s with increments of 1 m/s. To compare the drag, ANOVA and simple linear regression models between CFD and mathematical models for absolute values and logarithmic transformations were used. No statistically significant variations between CFD and the analytical procedures were found (F = 0.335; p = 0.800; η 2 = 0.021). The linear regression models between CFD and analytical procedures showed a very high adjustment for drag in absolute values for Pugh, Schneau, and Nonweiler (R 2 = 0.996; Ra 2 = 0.992; SEE = 0.933) and after logarithmic transformation (R 2 = 0.996; Ra 2 = 0.995; SEE = 0.046).

Purpose:The current study examined the ability of handgrip strength (HGS) to predict leg muscle power, cardiorespiratory fitness, and movement behaviors in children. Methods:One hundred eighteen male children aged 10-13 years from primary and middle schools in Saudi Arabia were recruited for this cross-sectional study. Physical fitness tests included HGS, standing long jump (SLJ), and a 20-m shuttle run test (20mSRT). Daily movement behaviors (time spent on physical activity, sedentary activities, and sleep) were measured for seven consecutive days using accelerometers. A multiple linear regression analysis was conducted to analyze the ability of HGS to predict SLJ distance and 20 m SRT laps. Age and body mass index were also included in the model as covariates. Results:HGS was significantly correlated with SLJ distance (r = 0.44, p < 0.05), 20mSRT (r = 0.22, p < 0.05), sedentary time (r = 0.34, p < 0.05), and moderate to vigorous physical activity time (r = -0.36, p < 0.05). In the regression models, HGS had a significant positive effect on predicting SLJ distance (β = 2.64, p < 0.001). Age was found to be a significant predictor of 20mSRT (β = 3.65, p < 0.001). Conclusion:These findings highlight that HGS may serve as a simple and practical indicator of musculoskeletal fitness, aiding early detection of functional limitations and informing physical development strategies in children Saudi boys, suggesting that HGS may be used to predict SLJ distance in this population.

This study aimed to classify young tennis players into sub-groups (clusters) based on their performance and physical fitness determinants and to analyze their cluster assignment change over six weeks of intervention. A sample of young athletes aged 10-14 years was used, and players were classified according to their International Tennis Number (ITN) and various physical fitness metrics after a six-week specific training program. Clusters were also analyzed for cluster assignment changes across pre-test and post-test interventions. The results showed that the performance variables in all clusters improved at the end of the intervention. Specifically, ITN scores improved by an average of 15% (p < 0.05), the 5-m sprint times improved by 8.5% on average (p < 0.01), and the T-drill agility test showed a 10% reduction in completion time (p < 0.01). However, key determinants for cluster formation assessment scores differed, meaning that the training resulted in the physical fitness profiles changing over time. Improvement in 5-m sprint and T-drill agility tests showed that the current program was effective in improving movement characteristics that are vital to a tennis player. Movement between clusters was observed, with some players improving their classification while others regressed, highlighting the need for individualized training interventions to optimize player development. Individualized responses to training are common among young athletes, reflecting varying developmental stages. Clustering can help tailor training programs to the specific needs of different groups. In summary, this study highlights the effects of specific training on young tennis players and emphasizes the necessity of considering individual differences in growth and training responses.

Motor imagery – the mental simulation of movement without execution – activates motor networks with near-physical fidelity. Once considered ancillary, it is now central to neuroplasticity, enhancing skill acquisition, accelerating rehabilitation, and sustaining motor function across the lifespan. From stroke recovery to elite performance, motor imagery demonstrates that movement begins in cognition. As neurofeedback, brain–computer interfaces and virtual reality integrate with mental rehearsal, the boundary between thought and action becomes narrower. This perspective argues that motor imagery is not a cognitive accessory but the neurocognitive foundation of movement – a rehearsal mechanism through which the brain reshapes the body. In doing so, it supports the view that action is cognitively prepared before it is expressed.

Background: In recent years, padel-based interventions have been widely applied in junior and elite players of both genders concerning athletic performance, whereas evidence of their efficacy in trials that use simple randomization has not been well established. This study aimed to compare the effects of 8 weeks of padel training (PD) on the strength and power of untrained healthy children. Methods: Twenty-five children aged 11–15 years (12.36 ± 1.15 years) were randomly assigned into experimental (PD) (nine boys and five girls: 1.58 ± 0.04 m; 50.00 ± 6.75 kg; and 19.96 ± 1.95 kg/m2) and control (CT) (seven boys and four girls: 1.60 ± 0.05 m; 56.92 ± 2.75 kg; and 21.61 ± 1.02 kg/m2) groups. The PD group trained twice a week for 8 weeks, and the CT group did not follow any training program and did not participate in regular exercise or sports. Countermovement jump, medicine ball throw, handgrip, and 5 m sprint test results were measured at baseline and after the intervention in the padel sport group. Results: The results showed a significant interaction for training-induced responses in the sprint test (T5) (F = 10.55, p = 0.004, η2 = 0.31). No significant interactions were observed for handgrip strength (HG) (F = 3.90, p=0.06), the medicine ball throw (MBT) (F = 0.851, p = 0.37, η2 = 0.04), and the countermovement jump (F = 1.04, p =0.32, η2 = 0.04), with clear improvements from pre- to post-training in the PD group. After 8 weeks of training, the PD group showed increased performance in handgrip strength (p = 0.004), while the CT group had decreased velocity post-training (p = 0.011). Conclusions: The individual results in the PD group showed an improvement, which suggests that the practice of padel seems to be a good strategy for improving one’s fitness. It is suggested that 8 weeks of PD seem to be effective in improving strength- and power-related variables in healthy, untrained children. This could be considered an alternative to traditional sports to improve the body fitness of young children and should be applied in school-based programs and the sports club community. Also, more high-quality RCTs are needed in the future.

This study compared (i) the load-velocity relationship in the free-weight horizontal (HBP) vs. incline bench press (IBP) and (ii) the differences between general vs. individual load-velocity equations to estimate the one-repetition maximum (1RM) in the HBP and IBP. Thirty males (26 ± 3 years) performed four sessions: two dedicated to assessing the 1RM in the HBP and IBP, and another two to measure the mean propulsive velocity (MPV) reached against loads of 40–90% 1RM in the HBP and IBP. Individual load-velocity equations estimated the MPV from 30 to 100% 1RM in the HBP and IBP and the 1RM in each exercise. Furthermore, general equations estimated the 1RM in each exercise. The estimated MPV values associated with 30–100% 1RM in the HBP and IBP were compared. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) determined the reliability between the actual and estimated 1RM in both exercises. The results showed higher MPV in the HBP than in the IBP from 30 to 80% 1RM ( p < 0.001). General and individual equations provided acceptable estimates of the 1RM when using loads from 70 to 90% 1RM in the HBP and IBP (CV < 10% and ICC > 0.80) but not 40–60% 1RM (CV > 10% and ICC < 0.80). This study shows that the load-velocity relationship differs between HBP and IBP, with higher velocities reached in HBP. Furthermore, individual and general equations seem reliable in estimating the 1RM when using relative loads from 70 to 90% 1RM in the HBP and IBP.

Volleyball performance relies heavily on agility, strength, and the ability to change direction, yet there is limited research investigating these physical attributes across different age groups in youth volleyball players. The change of direction (COD) deficit—a metric that isolates directional efficiency by comparing agility to linear speed—may provide a more nuanced understanding of an athlete’s movement capabilities. The aim of this study was to investigate: (i) the differences in anthropometrics, lower limb strength/power, dynamic balance, linear sprint speed, and change of direction (COD) ability between young volleyball age groups; (ii) the effect of age on COD deficit in young volleyball players, and; (iii) the COD deficit predictors. A cross-sectional analysis of young volleyball athletes was conducted. Seventy-seven female volleyball players from three age groups (U13:12.43 ± 0.89; U16:14.38 ± 0.52; U18:16.78 ± 0.93) participated in standardized tests measuring their physical qualities. The older age groups (U18) were significantly taller, heavier, and faster in linear sprints than their younger counterparts. No significant differences between groups were observed in lower limb strength and power or dynamic balance. The U16 group demonstrated the lowest COD deficit. The regression analysis identified drop jump height (DJ) as the sole significant predictor of COD deficit, explaining 6.9