Normative Data for Critical Speed and D’ for High-Level Male Rugby Players

Kramer, M.; Clark, I. E.; Jamnick, N.; Strom, C.; Pettitt, R. W.

The critical speed (CS) concept is essential for understanding the aerobic and anaerobic fitness levels of athletes. While rugby players are expected to have moderate CS values and extremely high curvature constant (D’) values, normative data for these parameters are currently lacking. To address this gap, a study recruited 30 male rugby players from the Eastern Cape of South Africa to develop normative data for CS and D’.

All participants performed the running 3-minute all-out exercise test (3 MT) using global positioning system (GPS) technology to determine CS and D’. GPS data were utilized to calculate total distance covered and velocities achieved, while also examining pacing effects. Summary statistics, including mean ± standard deviation, were provided.

The results showed high total running speeds for the initial 150 seconds (S150s = 5.79 ± 0.59 m/s) and a total distance of 871.5 ± 71.9 meters covered during the 3 MT. Thirteen out of 30 subjects surpassed the 300 meter D’ value, with the mean D’ calculated as 288.2 ± 49.1 meters. The CS for the entire group was determined to be 3.87 ± 0.55 m/s.

The data derived from the 3 MT were categorized using stanine tables, allowing for the generation of normative data that can be compared with future performances and those across similar sporting domains. While differences in CS and D’ between forwards and backs were observed, there were no significant between-group differences (p > 0.05).

Comparisons with previous literature suggest that male rugby players exhibit higher CS values than female rugby players. Additionally, compared to Olympic distance runners, male rugby players display markedly higher D’ values and lower CS values. The 3 MT is deemed a useful procedure for assessing and prescribing high-intensity interval training for rugby athletes.

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