The aim of the present study was to propose a new and simple field assessment of inter-effort recovery and change of direction (COD) ability based on performance during the 30-15 Intermittent Fitness Test (30-15IFT, an intermittent, incremental shuttle-run test) using three different protocols. Forty team-sport players (22 ± 2 years) performed either (group A; n = 16) the original 30-15IFT and two modified versions, one without a rest period (i.e. continuous run, 30-15IFT-CONT) and one without COD (30-15IFT-LINE), or (group B; n = 24) the original 30-15IFT and a modified version with more COD (28-m shuttle instead of 40-m, 30- 15IFT-28m). Heart rate (HR), blood lactate concentration ([La]b), rating of perceived exertion (RPE) and maximal running speed were recorded for all tests. There was no statistical difference in either maximal HR (A: p = 0.07 and B: p = 0.94) or RPE (A: p = 0.10 and B: p = 0.97) between tests. Compared with the 30-15IFT (12.3 ± 2.5, p < 0.01) and 30-15IFT-LINE (11.3 ± 2.6, p = 0.07, ES = 0.61), [La]b was lower for 30-15IFT-CONT (9.6 ± 3.3 mmol.L(-1)). Compared with 30-15IFT, maximal running speed was higher for 30-15IFT-LINE (103.1 ± 1.7%, p < 0.001) and lower for 30-15IFT-CONT (93.2 ± 1.4%, p < 0.001), while it was similar for 30-15IFT-28m (99.7 ± 3.6%, p = 0.62). Maximal speeds reached after the four tests were significantly but not perfectly correlated (r = 0.74 to 95, all p < 0.001). Present results show that differences in the maximal running speed reached following different versions of the 30-15IFT can be used by coaches to isolate and evaluate inter- effort recovery (i.e. 30-15IFT vs. 30-15IFT-CONT) and COD (i.e., 30-15IFT vs. 30-15IFT-LINE) abilities in the field. Additionally, COD ability as evaluated here appears to be independent of shuttle-length. Key pointsThe comparison of the maximal running speed reached at the original 30-15IFT with these reached at two modified protocols (i.e., 30-15IFT-CONT and 30-15IFT-LINE ) enables a simple and field-based assess-ment of between-efforts recovery and COD abilities during high-intensity runs.These data can be used by coaches to complete the physical profiling of each player, which could high-light the need for specific training interventions.
Keywords: HR/speed relationship; High-intensity running; agility; field test; intermittent exercise.