New Findings: What is the topic of this review? It is generally accepted that sleep deprivation constitutes a predisposing factor to the development of thermal injury. This review summarizes the available human‐based evidence on the impact of sleep loss on autonomic and behavioural thermoeffectors during acute exposure to low and high ambient temperatures. What advances does it highlight? Limited to moderate evidence suggests that sleep deprivation per se impairs thermoregulatory defence mechanisms during exposure to thermal extremes. Future research is required to establish whether inadequate sleep enhances the risk for cold‐ and heat‐related illnesses. Relatively short periods of inadequate sleep provoke physiological and psychological perturbations, typically leading to functional impairments and degradation in performance. It is commonly accepted that sleep deprivation also disturbs thermal homeostasis, plausibly enhancing susceptibility to cold‐ and heat‐related illnesses. Herein, we summarize the current state of human‐based evidence on the impact of short‐term (i.e., ≤4 nights) sleep deprivation on autonomic and behavioural thermoeffectors during acute exposure to low and high ambient temperatures. The purpose of this brief narrative review is to highlight knowledge gaps in the area and stimulate future research to investigate whether sleep deprivation constitutes a predisposing factor for the development of thermal injuries.

We investigated the effectiveness of a short-duration training period including an overloaded (weeks 1 and 2) and a reduced training load period (weeks 3 and 4) on wellness, swimming performance and a perceived internal training load in eight high-level water-polo players preparing for play-offs. The internal training load was estimated daily using the rating of perceived exertion (RPE) and session duration (session-RPE). Perceived ratings of wellness (fatigue, muscle soreness, sleep quality, stress level and mood) were assessed daily. Swimming performance was evaluated through 400-m and 20-m tests performed before (baseline) and after the end of weeks 2 and 4. In weeks 3 and 4, the internal training load was reduced by 19.0 ± 3.8 and 36.0 ± 4.7%, respectively, compared to week 1 (p = 0.00). Wellness was improved in week 4 (20.4 ± 2.8 AU) compared to week 1 and week 2 by 16.0 ± 2.2 and 17.3 ± 2.9 AU, respectively (p =0.001). At the end of week 4, swimming performance at 400-m and 20-m tests (299.0 ± 10.2 and 10.2 ± 0.3 s) was improved compared to baseline values (301.4 ± 10.9 and 10.4 ± 0.4 s, p < 0.05) and the overloading training period (week 2; 302.9 ± 9.0 and 10.4 ± 0.4 s, p < 0.05). High correlations were observed between the percentage reduction of the internal training load from week 4 to week 1 (-25.3 ± 5.5%) and the respective changes in 20-m time (-2.1 ± 2.2%, r = 0.88, p < 0.01), fatigue perception (39.6 ± 27.1%), muscle soreness (32.5 ± 26.6%), stress levels (25.6 ± 15.1%) and the overall wellness scores (28.6 ± 21.9%, r = 0.74-0.79, p < 0.05). The reduction of the internal training load improved the overall perceived wellness and swimming performance of players. The aforementioned periodization approach may be an effective training strategy in the lead-up to play-off tournaments.

Dry-land resistance exercise (RT) is routinely applied concurrent to swimming (SWIM) training sessions in a year-round training plan. To date, the impact of the acute effect of RT on SWIM or SWIM on RT performance and the long-term RT-SWIM or SWIM-RT training outcome has received limited attention. The existing studies indicate that acute RT or SWIM training may temporarily decrease subsequent muscle function. Concurrent application of RT-SWIM or SWIM-RT may induce similar physiological alterations. Such alterations are dependent on the recovery duration between sessions. Considering the long-term effects of RT-SWIM, the limited existing data present improvements in front crawl swimming performance, dry-land upper and lower body maximum strength, and peak power in swim turn. Accordingly, SWIM-RT training order induces swimming performance improvements in front crawl and increments in maximum dry-land upper and lower body strength. Concurrent application of RT-SWIM or SWIM-RT training applied within a training day leads in similar performance gains after six to twelve weeks of training. The current review suggests that recovery duration between RT and SWIM is a predisposing factor that may determine the training outcome. Competitive swimmers may benefit after concurrent application with both training order scenarios during a training cycle.

Background: We aimed to investigate whether water polo players of different playing levels and positions differ in fitness parameters (i.e., strength, aerobic endurance, and anaerobic potential). Methods: Twenty-four water polo players were assigned to international- (IL) and national-level (NL) groups or to centers and peripherals. At the beginning of preseason training, maximal bench press strength was measured and a speed–lactate test (5 × 200m) was performed to determine the speed corresponding to lactate concentrations of 4.0 (V4), 5.0 (V5), and 10.0 (V10) mmol·L⁻¹. Results: Maximal muscular strength was similar between international- and national-level water polo players, but it was higher in centers than in peripherals (109.2 ± 12.2 kg vs. 96.9 ± 8.5 kg, p = 0.007). IL players showed higher V4, V5, and V10 compared to NL players (V4, IL: 1.27 ± 0.04 m·s⁻¹ vs. NL: 1.17 ± 0.06 m·s⁻¹), (V5, IL: 1.33 ± 0.03 m·s⁻¹ vs. NL: 1.22 ± 0.05 m·s⁻¹), and V10 (IL: 1.50 ± 0.31 vs. NL: 1.35 ± 0.06 m·s⁻¹) (p < 0.01)). However, no significant differences were detected between centers and peripherals inV4, V5, and V10. Conclusions: We suggest that V4, V5, and V10 distinguish playing level in water polo, whereas they are comparable between playing positions. Although maximal strength is similar between playing levels, it is different between playing positions.

Technical performance deterioration after a water polo game is related to the athletes' conditioning level. Blood lactate concentration was measured during a 5 × 200-m incremental swimming test in 10 male water polo athletes to calculate the velocities corresponding to 4.0, 5.0, and 10.0 mmol·L−1 lactate concentration (V4, V5, and V10, respectively) and define their conditioning level. All athletes participated in 5 competitive water polo games. Before (Pre), at half time (Mid), and after (Post) the first 2 games, handgrip strength and repeated sprint ability (8 × 20-m) were measured. Pre and Post the next 2 games, ball throwing velocity, shooting accuracy, and 400-m swim were evaluated. Pre, Mid, and Post the last game, the eggbeater kick test was performed. Handgrip strength, repeated sprint ability, 400-m swim performance, and ball shooting accuracy decreased after the game (8.4 ± 6.2%, 6.3 ± 3.4%, 7.0 ± 4.1%, and 20.3 ± 23.4%, respectively, p ≤ 0.05). V4, V5, and V10 were not significantly correlated with changes in physical or technical performance after the game. Performance in 400-m swim correlated with V4 and V5 whereas changes in 400-m swim Pre-Post, correlated with changes in ball shooting accuracy and throwing velocity (r = 0.73 and r = 0.80, p ≤ 0.05). These data suggest that V4, V5, and V10 may not correlate with performance decline in water polo. Interestingly, the 400-m swim test is connected with the decline in repeated sprints, ball shooting accuracy, and throwing velocity after a water polo game in well-trained athletes....