# Comparison of Ultra-Short Race Pace and High-Intensity Interval Training in Age Group Competitive Swimmers PMID: 37755863 Journal: Sports (Basel, Switzerland) Published: 2023-09-18 Authors: Papadimitriou K, Kabasakalis A, Papadopoulos A, Mavridis G, Tsalis G ## Question To examine acute responses of an ultra-short race pace training set on kinematic characteristics, biomarkers, heart rate, and perceived exertion and compare them with a HIIT set, both oriented to the 100 m freestyle event, in national-level adolescent swimmers. ## Summary This acute swimming study compared two high-intensity pool sets in the same 18 national-level adolescent swimmers. Ultra-short race pace training used 20 x 25 m front crawl at 100 m race pace with 35-second intervals, while the HIIT set used 5 x 50 m front crawl at maximal intensity with 3-minute intervals. USRPT produced faster swimming velocity but lower distance per stroke and stroke index, and it produced lower blood lactate, blood glucose, heart rate, and perceived exertion than the HIIT protocol. ## Population - Eighteen healthy national-level adolescent competitive swimmers, 8 boys and 10 girls, aged 13.5 +/- 0.1 years. - Sample size: 18 - Age: 13.5 +/- 0.1 years - Sex: 8 boys, 10 girls - Fitness level: National-level age-group competitive swimmers training 12 h and about 30 km per week. - Health status: Healthy ## Methodology - Randomized counterbalanced acute within-subject comparison of two swimming test protocols on separate days. - Two testing days with 24 hours of recovery before and between protocols. - Indoor 25 m swimming pool. - Randomized and controlled study design. ## Protocol - USRPT. - Modality: Front crawl swimming. - Work intervals: 25 m at 100 m pace, about 17 s in the example. - Recovery: 35 s between repetitions; 2 min between the two 10-repetition parts. - Sets or repetitions: 20 x 25 m, split into 10 x 25 m USRPT1 and 10 x 25 m USRPT2. - Intensity: Approximately 100% of 100 m best-performance pace. - Session duration: Core set duration not reported as a single total; includes 500 m of work with 35-s intervals and a 2-min mid-set rest. - Frequency: Single acute test. - Program length: Acute. - Progression: None. - HIIT. - Modality: Front crawl swimming. - Work intervals: 50 m at maximal intensity, about 32.5 s in the example. - Recovery: 3 min intervals. - Sets or repetitions: 5 x 50 m. - Intensity: Maximal intensity, approximately 103% of 100 m best-performance pace. - Session duration: Core set duration not reported as a single total; includes 250 m of work with 3-min intervals. - Frequency: Single acute test. - Program length: Acute. - Progression: None. ## Outcomes ### Swimming velocity Status: improved Swimming velocity was higher during USRPT1 and USRPT2 than HIIT: 1.61 +/- 0.20 and 1.60 +/- 0.20 vs 1.56 +/- 0.20 m/s. p < 0.001; eta2 = 0.70 ### Distance per stroke Status: worse/safety concern Distance per stroke was lower during USRPT1 and USRPT2 than HIIT: 1.41 +/- 0.81 and 1.46 +/- 0.23 vs 1.63 +/- 0.37 m. p = 0.007 and p < 0.001; eta2 = 0.20 ### Stroke index Status: worse/safety concern Stroke index was lower during USRPT1 and USRPT2 than HIIT: 1.82 +/- 0.70 and 1.78 +/- 0.71 vs 2.26 +/- 0.82 m2/s. p < 0.001 for both; eta2 = 0.60 ### Blood lactate Status: improved Maximal blood lactate was lower after USRPT1 and USRPT2 than HIIT: 8.7 +/- 0.8 and 10.0 +/- 0.9 vs 12.9 +/- 0.4 mmol/L. p < 0.001 and p = 0.001; eta2 = 0.90 ### Heart rate Status: improved Heart rate was lower after USRPT1 and USRPT2 than HIIT: 173 +/- 1 and 180 +/- 0 vs 196 +/- 1 bpm. p < 0.001; eta2 = 0.90 ### RPE Status: mixed RPE was lower after USRPT1 than HIIT, but full USRPT2 reached the same reported RPE value as HIIT. USRPT1 vs HIIT: 7 +/- 0 vs 8 +/- 0, p = 0.015, eta2 = 0.30 ## Practical Insights - In trained adolescent swimmers, shorter race-pace 25 m repeats can produce lower acute physiological load than longer maximal 50 m repeats. - Interval structure changes the balance between speed, lactate, heart rate, perceived exertion, and efficiency metrics. - USRPT evidence from this paper is best treated as sport-specific acute performance evidence, not general consumer HIIT evidence. ## Limitations - Small sample - Acute-only comparison - No long-term performance or adaptation outcomes - Specialized athlete population - Swimming-specific protocol and equipment - No explicit adverse event reporting beyond safety procedures ## Safety And Adherence - The public extraction did not identify a specific safety or adherence note. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/37755863/) (pubmed) - [DOI](https://doi.org/10.3390/sports11090186) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10537129/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.