Background: Swimming performance depends on a wide variety of factors; however, the interaction between these factors and their importance varies between events. In sprint events, the characterized pacing underlines its specific development, as swimmers must achieve the highest possible speed while sustaining it to the greatest extent possible. Objectives: The aim of this review was to identify the key factors underlying sprint swimming performance and to provide in-depth and practical evidence-based information to optimize performance. Methods: The review protocol was not registered. PubMed, Web of Science and Scopus databases were searched up to October 31, 2023. Studies involving competitive swimmers and investigating sprint swimming performance were included, while studies conducted with young or masters’ swimmers, triathletes or waterpolo players or not investigating sprint swimming performance were excluded. The Downs and Black Quality Assessment Checklist was performed on the included articles to assess the methodological quality. Results: After applying the PICOS framework, 39 of the 1330 articles initially identified were included according to the PRISMA guidelines. The included records focused mainly on dry-land strength and in-water forces of both upper and lower limbs. A wide range of kinematic variables were also examined, together with the importance of anthropometric and various physiological parameters. Conclusion: This review highlights the importance of developing muscular strength and effectively transferring it to performance in the water. The evidence suggests that muscular development should prioritize enhancing velocity and effective displacement, rather than merely increasing force and performance in loaded tests. However, further research is needed to confirm this. While in-water forces have been well studied, there is a notable lack of analysis regarding drag. The optimal balance between stroke rate and stroke length should be determined individually, with a primary focus on achieving a high stroke length from a high stroke rate. Although anthropometry may play an important role in performance, the interaction of these traits appears to be complex, suggesting that other factors may be more important in determining performance outcomes. From a physiological perspective, the results indicate that the lactate peak and rate of accumulation should be thoroughly developed. Notwithstanding, this review shows the lack of a solid body of knowledge on the importance of anaerobic and especially aerobic factors. Finally, the absence of a list of potential confounders, together with the lack of high-quality studies involving elite swimmers (level 1 and 2), complicates the interpretation of the results.

The prominence of undulatory underwater swimming (UUS) has been clearly observed during recent international events. Improvement of this phase is important for overall performance. The aim of this systematic review was to identify the key factors that modulate UUS performance and provide coaches and sports science practitioners with valuable and practical information to optimise it. PubMed, Web of Science, Scopus, and SPORTDiscus databases were searched up to 14 October 2021. Studies involving competitive swimmers and which included UUS performance assessment were considered. Methodological quality assessment was conducted for the included articles. From the 193 articles screened, 15 articles were included. There was a substantial body of research conducted on kicking frequency, vertical toe and body wave velocity, angular velocity of the joints, distance per kick, joint amplitudes and mobility, and body position in UUS performance. However, further investigation is required for muscle activation and muscle strength influence. The results from this review contribute to understanding of how to optimise UUS performance, identifying the key aspects that must be addressed during training. Specifically, the caudal momentum transfer should be maximised, the upbeat duration reduced, and the frequency that best suits swimmers’ characteristics should be identified individually.

In swimming, the underwater phase after the start and turn comprises gliding and dolphin kicking, with the latter also known as underwater undulatory swimming (UUS). Swimming performance is highly dependent on the underwater phase; therefore, understanding the training effects in UUS and underwater gliding can be critical for swimmers and coaches. Further, the development of technique in young swimmers can lead to exponential benefits in an athlete’s career. This study aimed to evaluate the effects of a training protocol on UUS and underwater gliding performance and kinematics in young swimmers. Seventeen age group swimmers (boys = 10, girls = 7) performed maximal UUS and underwater gliding efforts before and after a seven-week training protocol. Time to reach 10 m; intra-cyclic mean, peak, and minimum velocities; and gliding performance improved significantly after the training protocol. The UUS performance improvement was mostly produced by an improvement of the upbeat execution, together with a likely reduction of swimmers’ hydrodynamic drag. Despite the changes in UUS and gliding, performance was also likely influenced by growth. The findings from this study highlight kinematic variables that can be used to understand and quantify changes in UUS and gliding performance.

In swimming, the beneficial effects of the in-water warm-up are often undermined by the long transition periods before competition (≥ 20 min). For that reason, studies comparing the effects of in-water warm-ups followed by dryland activities have been conducted in the swimming literature. This has brought conflicting evidence due to large combinations of supervised and unsupervised warm-up procedures used. Therefore, a scoping review was performed to discuss (1) why warm-up strategies are important for competitive swimming; to identify (2) what are the different warm-up approaches available in the literature, and; to establish (3) what are the main conclusions, considerations and gaps that should be addressed in further research to provide clearer guidance for interventions. The search was conducted on PubMed, Web of Science, Scopus, and SPORTDiscus databases. To be considered eligible, studies must have assessed acute short-term responses of warm-up procedures in swimmers by using randomized controlled trials or pre-post study designs. A total of 42 articles were included in this review. The effectiveness of warm-up responses was evaluated based on the inclusion or not of warm-up, the type of conditioning activity (in-water exercise, in-water exercise combined with dryland or dryland exercise only), its duration, and intensity. (1) Warm-up mechanisms have been mainly related to temperature changes associated to cardiovascular adaptations and short-term specific neuromuscular adaptations. Thus, maintaining muscle activity and body temperature during the transition phase immediately prior to competition could help swimmers' performance; (2) the most common approach before a race usually included a moderate mileage of in-water warm-up (~ 1000 m) performed at an intensity of ≤ 60% of the maximal oxygen consumption, followed by dryland protocols to keep the muscle activity and body temperature raised during the transition phase. Dryland activities could only optimize performance in sprint swimming if performed after the in-water warm-up, especially if heated clothing elements are worn. Using tethered swimming and hand-paddles during warm-ups does not provide superior muscular responses to those achieved by traditional in-water warm-ups, possibly because of acute alterations in swimming technique. In contrast, semi-tethered resisted swimming may be considered as an appropriate stimulus to generate post-activation performance enhancements; (3) nothing has yet been investigated in backstroke, butterfly or individual medley, and there is a paucity of research on the effects of experimental warm-ups over distances greater than 100 m. Women are very under-represented in warm-up research, which prevents conclusions about possible sex-regulated effects on specific responses to the warm-up procedures.

This study aimed to 1) examine the associations between two swim-specific measures of anaerobic performance and dry-land strength-based variables; 2) study the association between the aforementioned variables with swimming performance and its kinematics; 3) analyse sex-induced differences. Twenty-three regional-national swimmers performed five countermovement-jumps and pull-ups, 50-m front crawl, two 30-s tethered-swimming tests at 0 and 1.124 m·s⁻¹ water flow speed. Moreover, 10, 15, 20, and 25-m maximal front crawl were performed to determine anaerobic critical velocity (AnCV). The AnCV was positively correlated with tethered swimming variables in both conditions and dry-land-based variables in both sexes (p < 0.05). Tethered-swimming variables in both conditions were correlated with pull-ups’ average propulsive force in males (p < 0.05). 50-m swimming performance was positively associated with AnCV, tethered-swimming variables, countermovement-jump height, and pull-ups’ average propulsive force for both sexes (p < 0.05). Stroke rate (SR) was positively associated with AnCV in males and females (p < 0.05). Stroke length was correlated with tethered-swimming variables in males (p < 0.05). Except for SR, males presented higher values than females (p < 0.05). Depending on the conditions of their training environment, coaches might use the AnCV and tethered-swimming variables as interchangeable tools for evaluating anaerobic performance.

Performance intra-variability has not been studied in long-distance swimming. The aims were to describe the pacing profile in 400-, 800- and 1500-m freestyle events and to analyse the variability (coefficient of variation[CV]) and performance progression (%Δ) within and between rounds. A total of 256 swims of 130 elite-swimmers (70 males and 60 females) were analysed at the 2021 European Championship (indoor long-course). Linear mixed-effect models were applied for each swimmer and race time performances to obtain the CV and %Δ between each lap and rounds (i.e. heats and final). T-test was conducted to compare the CV between medallist and non-medallist. First and last laps were the fastest (p < 0.001) in all events compared to the intermediate laps which showed an evenly-pace. Parabolic pacing profile was adopted in all events. Male swimmers obtained a CV-average of 0.52 ± 0.49% between rounds (−0.64 ± 0.8%Δ) and females, a CV-average of 0.70 ± 0.45 (−0.71 ± 0.92%Δ). Medallist swimmers obtained higher CV between rounds (1.00–1.08%) compared to non-medallist finalist (0.22–0.47%). Parabolic pacing profiles were adopted in 400-, 800-, and 1500-m races. The best swimmers adopt conservative strategies in heats to improve their performance in final, obtaining higher CV and %Δ between rounds.