The aim of this study was to characterize multidimensional external-load profiles obtained from sensor-based tracking data over a four-month competitive period in an elite men's handball team and to investigate their associations with the session type, the playing position, and weekly workload fluctuations, as measured by the acute:chronic workload ratio (ACWR). Data were collected from 23 elite players using an ultra-wideband tracking system. Six variables, i.e., total distance, maximum speed, accumulated acceleration load (AAL), the number of exertions, maximum jump height, and the number of jumps ≥0.30 m, were standardized and clustered using k-means (k = 4). The cluster with the highest composite z-score was defined as a high load. The association between weekly density of high-load sessions and the likelihood of an ACWR spike (≥1.30) was tested using logistic regression. Results showed that match sessions were 1.8 times more likely than training sessions to fall into the high-load cluster. Wings and center-backs were significantly more represented in high-load clusters than goalkeepers and pivots. Additionally, when 15% or more of the previous week's sessions were classified as of the high load, the odds of an ACWR spike in the following week increased by 10.7 times. These findings suggest that data-driven (unsupervised) clustering of external-load variables supports early identification of high-risk workload patterns. Monitoring the weekly distribution of high-load sessions may help mitigate fatigue-related maladaptation by enabling proactive, position-specific load management in elite handball.

Soccer is an intermittent sport requiring rapid recovery from repeated high-intensity efforts, especially under heat stress conditions. Cooling vests have emerged as a practical strategy to enhance post-exercise heat dissipation, yet their physiological effects remain underexplored. This study aimed to assess the efficacy of a cooling vest following a repeated shuttle sprint ability (RSSA) test under hot conditions, focusing on skin temperature, blood lactate, and heart rate responses. Eleven recreational male soccer players completed two RSSA tests in a randomized crossover design, each followed by 15 min of passive recovery with or without a cooling vest. Skin temperature was measured at five anatomical sites, while blood lactate and the heart rate were recorded at baseline, pre-test, and at 0, 1, 3, 5, 10, and 15 min post-exercise. Compared with the control condition, the cooling vest intervention significantly reduced skin temperature at the 3rd and the 5th min post-exercise (3 min: dz = -1.54, 95% CI [-2.53, -0.55], p < 0.001; 5 min: dz = -0.90, 95% CI [-1.71, -0.08], p = 0.016). Transient between-condition differences were also observed for blood lactate at the 3rd and the 5th min (3 min: dz = -1.00, 95% CI [-1.95, -0.006], p = 0.022; 5 min: dz = -1.34, 95% CI [-2.36, -0.31], p = 0.003) and for the heart rate at 1 min post-exercise (dz = -0.84, 95% CI [-1.59, -0.09], p = 0.013). No consistent differences were found at other time points. The protocol showed high between-day reliability (CV = 2.47%; ICC = 0.75), supporting the validity of the observed effects. In conclusion, post-exercise use of a cooling vest after repeated sprints in the heat accelerates early superficial thermal recovery, as evidenced by reductions in skin temperature during the first minutes of recovery. Transient and isolated differences were also observed for the heart rate and blood lactate concentration; however, these effects were not sustained across the full recovery time-course. From a practical perspective, cooling vests may be useful during short recovery windows in intermittent sports, while further research is needed to determine whether broader or longer-lasting physiological benefits can be achieved.

This study examined the relationship between training load (TL) indicators and recovery status (total quality recovery, TQR) during the preseason training period in collegiate Taekwondo athletes. A total of 25 athletes (17 males and 8 females; age: 19.2 ± 1.04 years, training experience: 6.8 ± 3.40 years, body height: 168.0 ± 8.08 cm, body mass: 64.1 ± 8.38 kg, fat content: 15.9 ± 7.21%) participated in this prospective observational study. Over eight weeks, 855 training sessions were monitored. TL was quantified using the session rating of perceived exertion (sRPE) method, and derived TL indicators [weekly load variation (SDΔ), rolling average acute:chronic workload ratio (RA ACWR), exponentially weighted moving average acute:chronic workload ratio (EWMA ACWR), training monotony (TM), and training strain (TS)] were calculated. Recovery status was assessed daily using the TQR scale. In the univariate linear mixed model analyses, SDΔ (β = -0.30, 95% CI [-0.51, -0.08], p = 0.006) and the EWMA ACWR (β = -0.46, 95% CI [-0.64, -0.29], p < 0.001) were significantly associated with TQR. However, in the multivariate model, only the EWMA ACWR (β = -0.74, 95% CI [-0.97, -0.52], p < 0.001) remained a significant predictor. These findings suggest that the EWMA ACWR is the most sensitive TL indicator for capturing short-term changes in recovery status. Integrating the EWMA ACWR with simple tools such as the TQR scale may help coaches balance TL and recovery in preseason training. Future studies should include additional physiological and psychological markers to evaluate whether EWMA ACWR-based load management can effectively reduce injury risk and enhance athletic performance.

High-intensity interval training (HIIT), CrossFit®, strength training, and others, develop athletes' strength, speed, and endurance within a very short period of time, enabling competition at the highest sporting level. At present, they constitute one of the most widely practiced training modalities, used both in competitive and recreational sports. However, excessive intensity of such training sessions provokes substantial muscle damage (rhabdomyolysis) and may lead to renal injury, which in severe cases is diagnosed as acute kidney injury (AKI). This necessitates hospitalization and renal replacement therapy, thereby affecting athletes' health status and limiting their ability to participate in sports activities. The present work is a review of current knowledge on the phenomenon of rhabdomyolysis, its etiological factors, pathomechanisms, and health consequences, accompanied by a concise overview of emerging biomarkers of renal injury. The assessment of these biomarkers following physical exercise may provide new insights into the dynamics of post-exercise changes, indicate the severity and localization of exercise-induced renal damage, and contribute to a deeper understanding of structural kidney injury associated with strenuous physical activity-knowledge that may be applied in the prevention of exertional kidney injuries.

Concurrent training (CT)-the integration of strength and endurance exercises within the same session or cycle-is widely implemented in team sports. However, its optimal configuration and the conditions under which the so-called "interference effect" occurs remain subjects of debate. This narrative review critically examines the factors influencing CT efficacy in team sports, emphasizing the roles of training sequence, inter-session recovery, the endurance-training modality, and athletes' strength levels. Thirteen experimental studies involving male and female athletes from various team sports and competitive levels were analyzed. The evidence suggests that CT may effectively enhance both strength and endurance capacities when properly structured. Performing strength training before endurance training, or separating sessions by at least six hours, appears to minimize neuromuscular fatigue and preserve positive performance adaptations. Conversely, high volumes of endurance training or insufficient recovery periods tend to intensify the interference effects, particularly in speed- and power-related outcomes, which are often more pronounced in top-level athletes. Overall, CT may be a viable strategy for optimizing multiple physical qualities in team-sport environments, provided that its variables are carefully and systematically manipulated. This review also highlights the need for long-term interventions and female-specific studies to refine current practices and strengthen the evidence base in applied high-performance settings.

The increase in the competitive level and popularity of handball necessitates the optimization of training methods, particularly in the development of explosive strength, which determines jump effectiveness and overall game performance. This study analyzed the impact of specific power training and conventional resistance training on jumping abilities of young handball players. A total of 48 athletes were selected for the experiment and randomly assigned to a power training (PT) group, a resistance training (RT) group, or a control (C) group. The training program included plyometric exercises, dynamic neuromuscular activations, and reaction-time-based stimuli, with their effects evaluated through vertical jump tests (CMJ and SJ). The results indicated significant increases in jump height, maximum power, and relative maximum power in the PT group (p &lt; 0.05), suggesting that specific power training more effectively supported the development of dynamic variables than standard resistance training methods. While the RT group demonstrated gains in strength, the corresponding improvements in vertical jump performance were modest and not as substantial as those seen in the power training group. The findings highlight the crucial role of neuromuscular mechanisms in generating explosive power, as well as the importance of training methods based on the stretch-shortening cycle.

This systematic review evaluated the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on running economy (RE) in endurance runners. The search was completed in March 2024 based on research databases, and the language of publication was restricted to English. The primary outcome measure was RE, and it was categorized into three subgroups: Zone 1 (Z1), Zone 2 (Z2), and Zone 3 (Z3). The secondary outcomes assessed were maximal oxygen uptake (VO2max) and blood lactate concentration. HIIT significantly improved RE compared to MICT (SMD = 0.44, 95% CI [0.15, 0.72], Z = 3.01, p < 0.05). MICT showed a greater effect on VO2max (MD = 2.48, 95% CI [1.61, 3.34], Z = 5.60, p < 0.05). HIIT was more effective at reducing blood lactate levels (MD = -0.15, 95% CI [-0.28, -0.02], Z = 2.20, p < 0.05). The results indicate that HIIT was more effective than MICT in enhancing RE and delaying lactate accumulation. HIIT can further improve RE and postpone blood lactate accumulation when performed at or below the lactate threshold (≤ Z2). VO2max was more pronounced with MICT. These findings suggest that endurance runners and coaches should choose appropriate methods to optimize physiological adaptations.

In official judo competitions, athletes often participate in multiple bouts with short recovery intervals, leading to progressive fatigue that impacts neuromuscular performance. This study examined the acute effects of four simulated judo bouts on bilateral strength deficit (BLD) using metrics from countermovement jumps (CMJs). Thirteen male national-level judo athletes (21.4 ± 2.9 years) participated in the study. Athletes performed both unilateral and bilateral CMJs in randomized order: first at baseline before the initial match, and then after each of the four subsequent matches. The CMJ metrics evaluated included peak and mean power, jump height, peak force, peak velocity, and vertical net impulse. The study used the typical error (TE) and the intraclass correlation coefficient (ICC) to assess relative and absolute reliability. To compare CMJ metrics across the matches, the Friedman test with Conover's post hoc analysis was conducted, with statistical significance set at p < 0.05. The main findings showed excellent relative reliability, with an ICC greater than 0.85 for all variables in both limbs. Significant effects of the judo matches were observed only in the CMJ impulse (which decreased after the third match) and in BLD of impulse, which increased after the third match (p < 0.05). No statistically significant changes were found in other CMJ metrics. These results suggest that while successive judo bouts induced significant fatigue and force deficits, detectable through changes in impulse, other CMJ metrics remained unaffected. This may indicate that the capacity to generate force quickly in the lower limbs is primarily impacted by successive judo bouts.

There is currently a lack of knowledge about the rotational component of competitive starting techniques using starting blocks equipped with an adjustable back plate and its effect on water entry. The aim of the present study was to examine the angular momentum components of the current competitive swimming starts and to compare the contribution of the body segments to the rotational component of the individual kick start and the relay step start techniques. The block and aerial starting movements of eleven competitive swimmers during an individual and relay start from an Omega OSB11 were filmed at 120 Hz. The total body and the segmental contributions to the intrinsic and orbital components of the angular momentum were computed. Regardless of the type of the start, the orbital rotation of the body segments around the swimmer's centre of mass accounted for a large proportion (between 89 and 91%) of the total angular momentum. At the take-off, the total angular momentum was greater in relay step starts than in individual kick starts (η2 = 0.71). However, the competitive swimmers showed larger lower limb entry angles during the individual kick start (291.5 ± 1.8° vs. 282.2 ± 3.4°), related to a greater segmental contribution of lower limbs (56.5% ± 2.8) to the total angular momentum (η2 = 0.76). The adjustable back plate of the block provided a greater rotational component for the lower limbs in the individual kick start (compared to the relay step start), which assisted swimmers in achieving a better body posture at the water entry.

The present study aimed to explore the acute effects of a novel preloading strategy on squat jump (SJ) kinetics and kinematics from 0 to 50% body mass. Twenty-one male college athletes (mean ± SD: age = 23.29 ± 3.15 yrs, body mass = 75.50 ± 6.20 kg, body height = 178.07 ± 6.45 cm and body fat content = 13.71 ± 5.45%) completed three different jump tasks across two testing sessions: a SJ, a preloaded SJ (10-50% body mass) and a countermovement jump (CMJ). Applying preloading before the SJ resulted in significant, trivial to small increases in jump height (F(5,15) = 3.76 , p = 0.01, η2 = 0.16). However, there was no significant effect of preloading on peak power, peak force and peak velocity. The maximum peak power (5128.28 ± 459.38 W vs. 5047.97 ± 447.67 W, p = 0.04; g = 0.17) and maximum peak force (1810.72 ± 150.35 N vs. 1775.50 ± 155.54 N, p = 0.03; g = 0.25) were reached at the load of 20% body mass, which was significantly higher than in the SJ with no preloading applied. Jump height, peak force and peak velocity in the 10-50% body mass preloading SJ tests were not significantly different from those in the CMJ. Preloading before a SJ results in meaningful improvements in jump performance, particularly in peak power. Athletes in sports requiring high jump performance can use preloading SJ strategies to enhance lower limb explosive power and jump height.