Preliminary evidence of transient fatigue and pacing during interchanges in rugby league.
OBJECTIVE
This study aimed to quantify changes in heart rate (HR) and movement speeds in interchanged and whole-match players during 35 elite rugby league performances.


METHODS
Performances were separated into whole match, interchange bout 1, and interchange bout 2 and further subdivided into match quartiles. Mean percentages of peak HR (%HR(peak)) and total and high-intensity running (> 14 km/h) meters per minute (m/min) were recorded.


RESULTS
For whole-match players, a decline in high-intensity m/min and %HR(peak) was observed between successive quartiles (P < .05). High-intensity m/min during interchange 1 also progressively declined, although initial m/min was higher than whole match (24.2 ± 7.9 m/min vs 18.3 ± 4.7 m/min, P = .018), and %HR(peak) did not change over match quartiles (P > .05). During interchange 2, there was a decline in high-intensity m/min from quartile 1 to quartile 3 (18 ± 4.1 vs 13.4 ± 5 m/min, P = .048) before increasing in quartile 4. Quartiles 1 and 2 also showed an increase in %HR(peak) (85.2 ± 6.5 vs 87.3 ± 4.2%, P = .022).


CONCLUSIONS
Replacement players adopted a high initial intensity in their first match quartile before a severe decline thereafter. However, in a second bout, lower exercise intensity at the outset enabled a higher physiological exertion for later periods. These findings inform interchange strategy and conditioning for coaches while also providing preliminary evidence of pacing in team sport.
Dept of Sport and Exercise Sciences, University of Chester, Chester, UK.
Mark
M
Waldron
Jamie
J
Highton
Matthew
M
Daniels
Craig
C
Twist
D000054:Acceleration; D000704:Analysis of Variance; D054874:Athletic Performance / Q000502:physiology*; D005221:Fatigue / Q000503:physiopathology*; D005538:Football / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D005082:Physical Exertion / Q000502:physiology; D055815:Young Adult