Acute Physiological Responses of Very Short versus Standard Sprint Interval Training (SIT) Protocols

BENITEZ-FLORES, STEFANO; DE SOUSA, ARILSON F. M.; DA CUNHA TOTÓ, ERICK CARLOS; ROSA, THIAGO SANTOS; DEL ROSSO, SEBASTIAN; FOSTER, CARL; BOULLOSA, DANIEL

Denver

Congreso; American College of Sports Medicine (ACSM) 2017 Annual Meeting; 2017

American College of Sports Medicine

Sprint Interval Training (SIT) is characterized by supramaximal ?all-out? efforts of 10-30s, and promotes cardiometabolic and musculoskeletal adaptations. Given that peak power output, a key stimulus for aerobic adaptations, can be achieved during the first seconds of a sprint, it is possible that a very short SIT protocol (i.e., 5 s) can lead to similar adaptations compared to longer efforts.PURPOSE: To compare the physiological and mechanical responses of two different SIT protocols [(SIT with 20s efforts (SIT20s) vs. SIT with 5s efforts (SIT5s)].METHODS: Eight males (VO2max = 45.9 ± 3.7 mL/kg/min, age=25.3 ± 3.6 yr) participated. VO2max was measured in the 1st session. In the 2nd and 3rd sessions two different SIT protocols were completed in randomized order: SIT20s (4 × 20s with 2 min of recovery) and SIT5s (16 × 5s with 24 s of recovery). Both SIT sessions had the same load (7.5 % body mass), lasted 12 min, and had the same work-to-rest ratio. During SIT sessions, the following parameters were recorded: oxygen consumption (VO2), heart rate (HR), respiratory exchange ratio (RER), energy expenditure (EE), post-exercise lactate (LA), peak power (PP), mean power (MP), rate of fatigue (RF), total work (TW), and OMNI-cycle scale RPE (Omni-cycle RPE).RESULTS: Mean VO2, HR, and total EE were higher in SIT5s [37.61 ± 1.45 vs. 26.89 ± 1.21 ml/kg/min (P= 0.000), 156 ± 11 vs. 141 ± 14 bpm (P = 0.021), and 102 ± 9 vs.73 ± 7 Kcal (P = 0.000), respectively]. LA and RER were higher in SIT20s [16.4 ± 2.5 vs. 14.6 ± 2.6 mmol/L (P = 0.032), 1.46 ± 0.6 vs. 1.19 ± 0.7 (P = 0.000), respectively]. MP and TW were higher in SIT5s [735.5 ± 72.8 vs. 595.6 ± 57.4 W (P = 0.001), and 56.6 ± 5.6 vs. 47.3 ± 4.4 kJ (P = 0.02), respectively]. No significant differences were found between protocols in PP [911.4 ± 60.5 vs. 909.1 ± 88.5 W (P = 0.937), for SIT5s and SIT20s, respectively]. RF was higher in SIT20s than in SIT5s [54.7 ± 5.9 vs. 39.4 ± 9 % (P = 0.001)]. Omni-cycle RPE at 10 min recovery was lower in SIT5s [3.5 ± 1.7 vs. 4.75 ± 1.5 (P=0.038)].CONCLUSIONS: Despite similar PP between protocols, the short SIT protocol (5s efforts) elicited greater cardiorespiratory responses, higher mechanical strain, and a lower fatigue and glycolytic activation when compared to the standard SIT protocol.