Ultra Short Race Pace Training (USRPT) in Swimming. Do the Volume and Interval Matter? A Scoping Review

Abstract

Background: Ultra-short race-pace training (USRPT) is designed to accustom swimmers to the pace of an event by using high volume and submaximal intensity with short intervals. However, due to imprecise data on volume and interval, further investigation is necessary. This scoping review aims to provide evidence-based insights into the advantages and disadvantages of recommended volumes and intervals during USRPT, guiding swimming coaches and offering practical advice regarding this training method. Methods: For this analysis, 90,613 studies from PubMed, Scopus, Web of Science, and Google Scholar were screened to examine the volume and interval of the USRPT method. Results: Only five studies met the inclusion criteria, were further assessed using a PRISMA-P document, and were analyzed for biases with the revised Cochrane risk-of-bias tool for randomized crossover trials. Excessive daily use of USRPT in training volume is discouraged due to potential psychological strain. Reaching failure should involve modifying variables such as intensity and interval. Additionally, interval periods should vary based on the targeted event’s physiological demands and the USRPT set’s volume. For short-distance events (50–100 m), it is recommended that USRPT protocols include a work-to-rest ratio of 1:1 or 1:2, allowing more time for aerobic contribution to replenish energy supplies (consistent with HIIT and SIIT principles). Conclusions: Further research on specific elements of USRPT, including volume and interval, is essential to identify the most effective training sets for swimmers across different distances and styles.

1. Introduction

Enhancing swimming performance requires the integration of both aerobic and anaerobic (alactic and lactic) energy systems [1,2], as well as technical proficiency [3]. Consequently, various physiological indicators such as heart rate (HR) [4,5], oxygen consumption (VO₂, VO_2peak, VO_2max) [6], blood lactate (BL) levels [7], and blood glucose (BG) concentration [8,9], together with perceived exertion (RPE) during a session [10], are used to assess swimmers’ training status pre-, during, and post-training. To optimize performance ahead of swimming events, coaches typically employ two main types of training: (a) high-volume, low-intensity and (b) low-volume, high-intensity regimens. These programs target the development of both aerobic and anaerobic energy systems. Papadimitriou [11] examined low-volume and high-intensity regimens, whereas the present systematic review will show the high-volume and low-intensity variation.

High-Volume and Low-Intensity Training Types

High-volume training (HVT) is characterized by increased meters, comprising the majority of training time, at low intensity (below or at the first ventilatory and lactate threshold). HVT is not the most efficient training modality for improving swimming performance compared to high-intensity variations [12,13]. On the other hand, a more efficient variation of HVT is polarized training. It is defined as having the highest percentage of meters below the first ventilatory and lactate threshold (Z1), followed by a relatively high percentage above the second ventilatory and lactate threshold (Z3), and only a small portion of training between the first and second ventilatory and lactate thresholds (Z2) (Zone 1 > Zone 3 > Zone 2) [14,15,16,17]. According to findings, polarized training improves performance in 100 m [18,19], decreases fat mass, and increases both maximal oxygen uptake and fat-free mass in national-level swimmers [19]. However, it is not a recommended approach for middle-distance swimmers, such as 400 m IM swimmers, who should benefit from specific training periods employing a threshold-oriented training intensity [20].

Similarly, pyramidal training is characterized by the highest percentage of meters below the first ventilatory and lactate threshold; however, it is followed by a higher percentage of training time between the first and the second ventilatory and lactate thresholds and the lowest percentage above the third ventilatory and lactate threshold (Zone 1 > Zone 2 > Zone 3) [16]. It is an efficient training type, especially for elite swimmers, significantly influencing performance in the 800 m, decreasing fat mass, and increasing maximal oxygen uptake and fat-free mass as well [19].

Generally, it is acknowledged that dedicating a substantial portion of training time (approximately 70% to 90%) to activities below the first ventilatory and lactate thresholds has a significantly positive impact on performance, particularly for both short- and long-distance swimmers [21,22,23,24]. Nonetheless, the prevailing standard in training practices, which many swimming coaches must address, emphasizes the inclusion of high-intensity anaerobic training methods, often resulting in a reduction of the total training volume. Over the past decade, ultra-short race pace training (USRPT) has emerged as an effective method for enhancing swimming performance by acclimating swimmers to event-specific pacing [25,26]. The concept of USRPT primarily stems from the research conducted by Astrand et al. [27] and Beidaris, Botonis, and Platanou [28], which highlighted the benefits of short-duration work intervals (sets of 25 and 50 m) paired with rest periods of approximately 20 s. A typical USRPT session consists of short, distance-specific bouts (15–100 m), brief rest intervals (15–25 s), and relatively high volumes (up to 5–10 times the distance of the targeted event).

Papadimitriou [11] discussed the factors of intensity and pace calculation, concluding that it is a type of training that needs to be further elucidated, according to the factors of intensity and pace calculation. However, other considerable points for this training method are the volume and the interval. The purpose of this systematic review is to provide valid statements identifying the pros and cons of the suggested volume and interval during a USRPT, orienting swimming coaches, and offering key messages and advice about this type of training.

2. Methods

A search of the literature was conducted, with no registration number, to find the most relevant articles on USRPT, from 7 April until 1 September 2024. Also, the studies’ identification was conducted according to the PRISMA-P document [29]. The article search was conducted using the most robust databases, including PubMed, Scopus, Web of Science, and Google Scholar. The volume and interval of the USRPT method were searched. The search strategy comprised “swimming” AND “ultra-short race pace training” OR “volume of training” OR “high-intensity training” OR “sprint intensity training”. Each database’s systematic equations and PRISMA checklists are presented in Figure A1, Appendix A, and Tables S1 and S2, Supplementary Files, respectively.

For a study to be included, the following was checked: 1. manuscripts in the English language, 2. full text availability, 3. human participants, 4. international-, national-, or regional-level swimmers, 5. acute or intervention effects of USRPT according to Rushall’s instructions: i. USRPT alone or combined with other training methods, ii. a minimum of three times for the targeted event, iii. intervals close to 20 s, 6. measurements that yielded results based on biomarkers, as well as physiological and biomechanical factors, and 7. all study types (original, narrative reviews, and systematic reviews).

The exclusion criteria were 1. not meeting the inclusion criteria, 2. participants were children (≤11 years old), 3. the volume of training was less than three times the targeted event, 4. intervals of less than 15 and more than 30 s, and 5. the studies examined only performance factors.

3. Results

The literature was reviewed by examining the studies’ titles and abstracts to match the searched keywords. A total of 90,613 studies were found using the included keywords. Then, removing duplicates and articles with different content, the remaining full-text studies were selected, screened, and compared to determine inclusion in the systematic review. Thirteen (13) studies were found that included in their title the keyword ultra short race pace training or USRPT; however, only five (5) articles met the inclusion criteria for the systematic review (PRISMA flowchart, Figure 1) and then were revised with the Cochrane risk-of-bias tool for randomized crossover trials [30], checking for the measurements that were conducted for the exact outcome (Tables S3–S5 Supplementary File).

USRPT protocols that were utilized in the experimental studies were 20 × 25 m on freestyle, with a 40-s interval working at a 100 m pace, with a BL response at the first ten (1–10 × 25 m), 8.7 ± 0.8, and the second ten (11–20 × 25 m), 10.0 ± 0.9 mmol·L⁻¹. Also, the blood glucose at the first and the second ten were 6.0 ± 0.9 and at 11–20 × 25 m: 6.4 ± 1.4 mmol·L⁻¹, respectively [9]. Moreover, the swimmers in both the first and second parts of USRPT (1–10 and 11–20 × 25 m) had a lower heart rate (HR) than the HIIT protocol with a large effect size (HR_(1–10), HR_(11–20) vs. HR_(HIIT): 173 ± 1, 180 ± 0 vs. 196 ± 1 beats per minute (bpm), p < 0.001, η² = 0.90) with a higher rate of perceived exertion (RPE) during the second half of USRPT than the HIIT protocol. Last but not least, in the kinematic variables, the swimmers had statistically significant lower distance per stroke (DPS), no difference in stroke rate (SR), lower stroke index (SI), and greater swimming velocity (SV) in USRPT than the HIIT protocol.

Cuenca et al. [31] utilized 20 × 50 m on freestyle, with a 1:1 interval working at a 200 m pace. The BL response in two minutes was 8.2 ± 2.4, and in five minutes, it was 6.9 ± 2.8 mmol·L⁻¹, and it was significantly lower than the protocol of race pace training (RPT), which consisted of 10 × 100 m and found 10.8 ± 2.7 and 10.1 ± 2.6 mmol·L⁻¹ in two and five minutes, respectively. Stoke count (SC) and swimming velocity (SV) were significantly higher and lower in RPT, respectively, whereas countermovement jump (CMJ) decreased after the RPT protocol.

Additionally, Williamson et al. [32] study used 20 × 25 m on freestyle, with a 35-s interval working at 100 m pace with BL response 7.7 ± 2.4 mmol·L⁻¹ after the first four repetitions, reaching 13.6 ± 3.1 mmol·L⁻¹ at the end of the set (20 repetitions). Similarly, the RPE from 8 ± 1.6 increased to 18 ± 1.6, whereas the average HRmax reached 188 ± 9 bpm at the end of the USRPT set. This protocol did not compare with any other HIIT variation. The conclusion was that the physiological burden of this protocol claims that USRPT is a highly demanded anaerobic training stimulus.

A similar conclusion was found in the two systematic reviews, claiming that USRPT is a modified HIIT protocol [11,33] with high anaerobic demands [11] that swimming coaches are advised to utilize as a part of a periodized training program incorporating more training methods and stimuli such as HIIT, SIIT, etc. [11,33]. Also, USRPT sets must be fitted to the demands of the race strategy, improving the performance that needs to be worked at a specific part of a race and avoiding the unique utilization of USRPT during a training unit or period (

Table 1. Experimental and review studies on USRPT protocols.

Authors	Participants	Training Content	Variables Studied	Results
Papadimitriou et al. [9]	18 swimmers (8 ♂ and 10 ♀) 13.5 ± 0.1 years WA points > 500	USRPT: 20 × 25 m front crawl @40 s on 100 m pace HIIT: 5 × 50 m front crawl @3 min	Acute response and comparison of BL, BG, DPS, SR, SV, SI, HR, and RPE	HIIT DPS ↑ SI ↑ BL ↑ HR ↑	USRPT SV ↑
Papadimitriou [11]	-	-	Systematic review	USRPT sets close to the average of an event without the contribution of the first split. Highly demanding anaerobic training stimulus. Lack of studies regarding blood lactate relevance to the targeted event.
Cuenca-Fernández et al. [31]	14 swimmers (? ♂ and ? ♀) 19.0 ± 1.6 and 19.0 ± 0.1 years WA points > 500	USRPT: 20 × 50 m front crawl @60 and 70 s for ♂ and ♀, on 200 m pace RPT: 10 × 100 m front crawl @130 and 140 s for ♂ and ♀, on 200 m pace	Acute response of BL, SC, and CMJ	RPT BL ↑ SC ↑ CMJ ↓ Compared to USRPT
Williamson, McCarthy, and Ditroilo [32]	14 swimmers (7 ♂ and 7 ♀) 20.0 ± 1.6 years Elite and Sub elite swimmers	USRPT: 20 × 25 m front crawl @35 s on 100 m pace	Acute response of BL, HR, and RPE	USRPT BL ↑ HR ↑ RPE ↑
Nugent et al. [33]	-	-	Systematic review	USRPT is a derivative of high-intensity training (HIT). USRPT is a training method that can be utilized in combination with other training methods and stimuli.

WA = World Aquatics; ♂ = males; ♀ = females; USRPT = ultra-short race pace training; @ = interval; HIIT = high-intensity interval training; BL = blood lactate; BG = blood glucose; DPS = distance per stroke; SR = stroke rate; SV = swimming velocity; SI = stroke index; HR = heart rate; RPE = rate of perceived exertion; ↑ = significant increased response; ? = not defined; RPT = race pace training; SC = stroke count; CMJ = counter movement jump; ↓ = significant decreased response.

).

4. Discussion

4.1. Volume Calculation

The training volume is crucial in constructing a training set, particularly a USRPT set. Rushall [25] asserts that if programming has been determined correctly, no swimmer will complete the maximum number of repetitions in a USRPT set. The conceptualization of this statement is that without failure, no performance improvement is possible; thus, in every USRPT set, a neural fatigue failure is experienced [26]. On the other hand, many coaches do not choose to use the maximum number of repetitions because, in a traditional training manner, the number of repetitions has to be completed [7].

Rushall’s statement is akin to the concept of resistance training for muscle hypertrophy, which demands high-volume routines (until failure) at moderate intensity (50–80%), generating successful metabolite buildup for muscle hypertrophy through the augmentation of mechanical tension, metabolic stress, and muscle damage [34]. In this context, failure in USRPT sets correlates with the swimmers’ ability to learn their pace. However, the concept of muscle hypertrophy, until the failure, is one viewpoint. Even bodybuilders utilize lower volume with higher intensity resistance training, varied in the tempo of lifting, to work the fast-twitch fibers, targeting muscle hypertrophy or maximal power [35], so have swimmers do.

Perhaps swimmers are motivated by the challenge of maintaining their pace for an extended period; however, the question arises: Can USRPT be implemented three or four times per week as a unique training stimulus for short or long training periodization? According to Rushall’s [36] guide, the volume of a USRPT session consists of short, distanced bouts (15–100 m) and rather high volumes (up to 3–10 times the distance of the targeted event), performed at the pace of the targeted event, thus, with submaximal to maximal intensity. The conceptualization behind this high training volume is that it allows swimmers to swim at the targeted race pace velocity for an extended period, thus contributing to their familiarization with it during a race [36]. However, the frequency of implementation of USRPT three or four times per week for an extended period may raise concerns about overtraining and potential fatigue accumulation. Balancing training volume, intensity, and recovery is essential to prevent overuse injuries and ensure optimal performance gains. Therefore, careful consideration and monitoring of training load are necessary when incorporating USRPT into a swimmer’s training regimen.

Guided by Rushall’s instructions, Papadimitriou et al. [9], Cuenca-Fernández et al. [31], and Williamson, McCarthy, and Ditroilo [32] implemented USRPT protocols in their studies, with one of the minimum volume burdens (5 times the targeted distance) for events of 100, 200, and 100 m, respectively, in freestyle style. However, in none of the studies was a failure recorded by the swimmers during the experimental process. Therefore, the volume of the USRPT sets was unsuitable to provide a precise stimulus according to Rushall’s USRPT principles. This observation is also consistent with Nugget’s et al.’s [36] study. According to their proposed guideline for the implementation of a USRPT set, in the seventh step, they suggest that swimmers must fail to sustain the interval velocity (or performance) on 2–3 repetitions. Thus, in future studies, protocols must be implemented that adhere more closely to USRPT guidelines and principles.

However, is this excessive USRPT volume psychologically tolerable for swimmers? The psychological aspect of training is crucial, and excessively high volumes may lead to mental fatigue, an increase in anxiety state, and a decrease in self-confidence [37]. Therefore, it is essential to consider both the physiological and psychological aspects when designing training protocols, ensuring they are both effective and sustainable for athletes.

Rushall proposes that a USRPT protocol should be implemented three to four times per week for two to three sets per session, depending on the distance of the targeted event [25]. This entails swimmers completing hundreds of 25 s and 50 s at a specific pace repeatedly. According to Rushall, a well-designed USRPT set provides a sufficient number of repetitions so that the swimmer goes through all the stages of a race and eventually reaches a neural fatigue state [26]. Additionally, the “Principle of Individuality” is another strength of USRPT. This principle acknowledges that each swimmer will reach the repetition they can tolerate, in contrast to traditional types of training where swimmers are expected to complete the set regardless of individual differences. This individualized approach can help optimize training adaptations and reduce the risk of overtraining or undertraining.

On the contrary, traditional swimming programs utilize training volumes varying from 50–300 m for sprints, 300–600 m for lactate production, 300–1200 m for lactate tolerance, 500–2000 m for intensities close to VO_2max, 1500–4000 m for threshold training, and 2000–6000 m for low-intensity aerobic training; hence it is more possible to complete a traditional training set. The above-mentioned training methods are typically utilized from two (high-intensity training programs) to six times per week (low-intensity training programs) [7]. Additionally, it is noteworthy to compare the suggested volume for a USRPT set with the volume variations of a traditional training plan. USRPT is demonstrated as a highly demanding anaerobic training stimulus, hypothesized based on blood lactate concentration and swimmers reaching failure, mainly due to depleting glycogen supplies [11] (

Table 2. Volume comparison between USRPT and traditional training set, according to the targeted event.

Events (m)	USRPT Approach (m)								Traditional Training (m)
	×3	×4	×5	×6	×7	×8	×9	×10
100	300	400	500	600	700	800	900	1000	HIIT and SIIT sets are implemented on volumes varying from 100 to 300 m.
200	600	800	1000	1200	1400	1600	1800	2000	HIIT sets are implemented on volumes varying from 200 to 600 m.
400	1200	1600	2000	2400	2800	3200	3600	4000	Combined HIIT, VO2max, and Threshold sets are implemented on volumes varying from 800 to 2000 m.
800	2400	3200	4000	4800	5600	6400	7200	8000	Combined HIIT, VO2max, and Threshold sets are implemented on volumes varying from 1000 to 3000 m.
1500	4500	6000	7500	9000	10,500	12,000	13,500	15,000	Combined HIIT, VO2max, and Threshold sets are implemented on volumes varying from 1000 to 6000 m.

The colors represent the possibility of implementing the suggested training volume. Green: High; Yellow: Moderate; Red: It is not suggested.

).

Discussing the table of training content in each event between USRPT and the traditional approach, it is challenging to imagine a swimmer completing 900 m at the pace of 100 m or 12,000 m at the 1500 m pace. Therefore, before implementing a USRPT set, a coach must consider the psychological burden on the swimmer with such a set [37]. Modifications in intensity and interval are crucial steps toward gradually increasing the difficulty of a USRPT set [11]. Consequently, the statement “without failure, no performance improvement is possible” must be applied by modifying intensity and interval rather than simply focusing on volume. Moreover, coaches should consider incorporating other training types for intensity variation and, more specifically, for contributions to different energy systems. Otherwise, swimmers may develop the ability to swim specific events without improving their overall swimming speed or stamina.

Take-home messages and statements are suggested:

The swimmers must implement USRPT until reaching failure under the prism of a training test set, regardless of the targeted event. Consequently, they will probably predict their performance and their tolerance according to the race demands. However, excessive utilization of USRPT in volume is preferable to be avoided by coaches as a daily routine because of the probable excessive psychological burden. Moreover, failure must be reached by modifying factors such as intensity and interval. On the other hand, USRPT is probably a solution for middle and especially long-distance swimmers, avoiding the excessive meters or yards that these swimmers have to swim. In conclusion, the presence of higher intensity and lower volume sets is also important for energy demand variations during a swimming event. Lastly, short-distance swimmers may not benefit from the volume of USRPT; therefore, the volume of other training types such as SIIT and HIIT sets must also be implemented.

4.2. Interval

According to Rushall’s statement, in a typical USRPT set, the variation in the interval period is between 15 and 25 s, with the most frequently used period being 20 s. Also, when a repetition is slower than the planned race pace, the swimmer skips the next repetition, allowing for extra rest. Finally, in a USRPT set, a swimmer can fail two more times after receiving extra recovery before the set is abandoned. Rushall regards these rest periods as essential to ensure that a true training effect is achieved [25,26].

The 20 s interval theory was supported by Beidaris, Botonis, and Platanou [28] (2010), who compared three resting variations (5, 10, and 20 s) in a set of 4 × 50 m, concluding that after the 20 s interval, physiological parameters did not change and were of higher intensity and greater performance compared to any other experimental conditions. Moreover, the 20 s rest period, used for interval repetitions of 50, 75, and 100 m, allows the brain to encode the significant aspects of each repetition [25]. On the other hand, in short intervals (e.g., 5 s), such as a broken swim, psychological and neuromuscular learning does not occur [25,37].

Papadimitriou et al. [9] and Williamson, McCarthy, and Ditroilo [32] followed Rushall’s theory and utilized intervals of 20 s (approximately 1:1), in contrast to Cuenca-Fernández et al. [31], who used a rest ratio of 1:1 in 20 × 50 m (they should implement 20 s of rest). Summarizing the shreds of evidence, this interval ratio (1:1) did not elicit any relevant BL response with the 200 m event, and it deviates significantly from Rushall’s interval theory, resulting in a lower physiological burden for the USRPT set. Beidaris, Botonis, and Platanou [28] found the effectiveness of 20 s intervals in a 200 m (4 × 50 m) volume set. However, this volume is far below the 1000–1200 m that a USRPT training session typically consists of. Rushall [25,26] states that when a swimmer is familiar with the 20 s rest, they can increase the difficulty of the set by decreasing the interval. However, this hypothesis has not been tested in any research.

Generally, the energy demands of a training set vary according to the duration and intensity of a training bout. The phosphagen system, anaerobic and aerobic glycolysis, and mitochondrial respiration interact to provide energy [38], particularly in submaximal bouts such as a USRPT set [9,11,31,36]. During submaximal bouts, a higher percentage of body energy demands can be restored during intervals by mitochondrial respiration [39], thereby enhancing both aerobic [34] and anaerobic ability [9,31,36]. On the contrary, with HIIT and SIIT methods, where the bouts are implemented at maximum intensities (>85% of HR or VO_2max) [40,41], longer interval periods are necessary to allow the swimmer time to recover aerobically and anaerobically [40,41], thereby removing BL from the muscles through the bloodstream.

Papadimitriou et al. [9] and Williamson, McCarthy, and Ditroilo [32] utilized a protocol for 100 m (20 × 25 m, at 100 m pace) with an interval of 20 s. On the other hand, Terzi et al. [39] and Kabasakalis et al. [8] implemented 4 × 50 m with a work-to-rest ratio of 1:4 and 8 × 50 m and 8 × 25 m with a work-to-rest ratio of 1:1, respectively (SIIT training protocols), observing high relevance to the 100 m event [40] and an increase in biomarkers such as BL, glucose, insulin, glucagon, cortisol, and uric acid [8]. Also, Papadimitriou and Savvoulidis [10] implemented a HIIT protocol consisting of 2 × 4 × 17.5 m with two interval variations with a work-to-rest ratio of 2:1 (10 s) and 1:3 (1 min). In both variations, independent of the rest period, amateur swimmers improved in performance tests, with a similar heart rate response after a four-week intervention. Therefore, even with a greater interval and much less volume, the physiological burden is relevant to a 100 m event, creating a strong stimulus for performance improvement; however, these SIIT methods and other high-intensity methods lack pace precision compared to the USRPT protocol.

Perhaps the general rule of 15–20 s between USRPT bouts may need clarifications. Coaches should consider the targeted event for which the USRPT protocol is implemented. For example, can a USRPT set oriented towards a 100 m event have the same interval (≈20 s) as a set for 400 m or a greater distance? Maglischo [7] suggests intervals varying from 5 to 20 s for sets ranging from 25 to 400 m at an intensity close to VO_2max. On the other hand, at higher anaerobic intensities (>VO_2max), the interval varies from 1:2 to 1:4 (HIIT and SIIT methods). Cuenca-Fernández et al. [31] were the only authors who utilized a USRPT set for 200 m (20 × 50 m) and a race pace training (RPT) (10 × 100 m) with a work-to-rest ratio of 1:1. According to Rushall [25,26], the interval is greater than the guidelines of a USRPT training, and this deviation can be inferred from the BL concentration, which was close to 8.2 ± 2.4 mmol·L⁻¹ and lacks relevance compared to the physiological burden of a 200 m event [42,43,44].

Take-home messages and statements are suggested:

Swimming coaches need a training set that can simultaneously improve and predict their swimmers’ performance. USRPT has great potential to be implemented by coaches for these reasons. However, it is suggested that interval variations depend on the physiological burden of the targeted event and the volume of the USRPT set. Therefore, it is proposed that for short-distance events (50–100 m), USRPT protocols consist of a work-to-rest ratio of 1:1 or 1:2, allowing more time for the aerobic contribution to fulfill energy supplies (HIIT and SIIT approach). On the other hand, for middle- and long-distance events (400–10,000 m), where intensity in a USRPT set is submaximal, a rest ratio ranging from 5 to 20 s, depending on the swimmer’s level and the desired challenge set by the coach, seems to fit better (

Table 3. Construction of a USRPT set according to different intervals. The intervals have been calculated according to the time that aerobic contribution has a high response.

Event (m)	Proposed Sets and Intervals During a USRPT (s)
50	2 × (10 × 10 m), @1:2
100	20 × 25 m, @1:1 or 10 × 50 m, @1:1
200	20 × 25 m, @1:1 or 10 × 50 m, @1:1
400	60 × 25 m, @10 s or 30 × 50 m, @20 s or 15 × 100 m, @40–60 s
800	60 × 50 m, @5–10 s or 30 × 100 m, @20 s or 15 × 200 m, @40 s
1500	90 × 50 m, @5–10 s or 45 × 100 m, @10–15 s or 20 × 200 m, @20–30 s or 10 × 400 m, @40–50 s
10,000	100 × 100 m, @5–10 s or 50 × 200 m, @10–20 s or 25 × 400 m, @20–30 s or 10 × 1000 m, @30–40 s

@ = interval.

).

5. Conclusions

USRPT has several misleading aspects, and its application often lacks precision regarding the implemented volume and interval. According to the risk of bias that was conducted, further research on specific elements of USRPT, such as volume and interval, should be clarified, and the most suitable training sets for swimmers across all distances and styles should be identified. Additionally, programming an effective training regimen is a complex task for coaches, as they need to balance training stimuli to achieve optimal results for their athletes. In this regard, coaches are akin to piano players, who skillfully press the keys (HVT, SIIT, USRPT, etc.) at the right moment, for the correct duration, and with necessary pauses (intervals) in between. Furthermore, USRPT appears to be a variation of HIIT with shorter intervals between bouts, which many coaches can adopt to leverage its physiological and coaching benefits.