Scrummaging is a major component of Rugby Union gameplay. Successful scrummaging is dependent on the coordination of the forward players and the strength of the eight individuals. The study aim was to determine whether individual scrummaging kinetics and other candidate factors associated with scrummaging performance discriminate team scrum performances. Sixteen club-level forwards (stature: 1.80 ± 0.1 m; mass: 99.0 ± 18.2 kg) were initially divided into two scrummaging packs. A total of 10 various scrum permutations were tested, where players were randomly swapped between the two packs. Winning scrums were determined by two observers on opposite sides of the scrum. Fatigue (100 mm visual analogue scale (VAS)) and scrummaging effort (6-20 rating of perceived exertion (RPE)) were assessed following each scrum contest. Individual scrummaging kinetics were acquired through an instrumented scrum ergometer and muscular power indicated through vertical jump heights. Student's t-tests were used to differentiate between winning and losing scrum packs. VAS and RPE were assessed using repeated measures ANOVAs. Winning scrum packs had significantly larger combined force magnitudes (p < .002), regardless of the player contribution calculations. Additionally, winning packs had less individual movement (p = .033) and higher combined vertical jump heights (p < .001) but were not significantly heavier (p = .759) than losing scrum packs. While perceived VAS and RPE values progressively increased (p < .001), no differences in the individual scrum magnitudes were observed between the 1st and 10th scrum (p = .418). The results indicated that the combination of individual forces, variation in movement and factors related to scrummaging performance, such as vertical jump height, were associated with team scrummaging success.

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Background: A rugby union game consists of 80 minutes of strenuous exertion. Forwards are required to participate in the arduous activity of scrummaging throughout a game.Objectives: The purpose of this study was to identify whether rugby-match simulated fatigue modified individual scrummaging technique and reduced performance.Methods: Twelve forwards (body mass 106.2±13.3 kg; stature 179.5±8.4 cm) had individual scrum kinetics and kinematics assessed prior to and following a protocol that simulated a rugby match. The simulated rugby match protocol required participants to run at various velocities and perform rugby specific tasks. Rating of Perceived Exertion (RPE) was assessed using a 6-20 Borg scale and Visual Analogue Scale (VAS). Blood lactate, heart rate and RPE were measured prior to, at mid-point and after the simulated game, while markers of muscle damage (blood creatine kinase activity (CK) and urea) were measured prior to and following the protocol.Results: RPE (p<0.0001) and VAS (p<0.0001) showed significant increases between the pre- and post-simulation values. Of the physiological markers, heart rate (p<0.0001) and blood urea concentration (p=0.004) increased following the match simulation. No significant differences were observed for blood CK (p=0.281), individual scrummaging forces (p=0.433) or in the kinematic variables following the protocol. While physiological fatigue and subjective ratings of physiological fatigue may develop during a rugby simulation, no differences were observed in peak forces or in body kinematics at peak force.Conclusion: Physiological fatigue does not influence individual scrummaging performance and technique.

Although the characteristic morphology of rugby forwards playing different positions in the rugby scrum has been well documented, a complete picture of the force characteristics that different players produce has not been evaluated. This is especially true for the movement of the centre of pressure (CoP) elicited during scrummaging in a forward direction. An individual scrummaging ergometer was therefore developed to measure the CoP of an individual scrum action using conventional torque calculations. Calibration of the measurement system revealed measured force errors within 16.6 N of the actual force and errors of less than 3.96 mm for CoP location determination. Thirty-nine club level rugby union players (22 front rows, 11 locks and six back rows) scrummed against the ergometer on an outdoor rugby field. Differences between the three groups were tested using one-way ANOVAs. The maximum force for different players was 2253.6 ± 649.0 N over the entire subject group. There were no differences in the individual compressive force between the groups [front rows: 2404.0 ± 650.3 N; locks: 2185.6 ± 568.9 N; back rows: 1826.9 ± 670.2 N (p = 0.143)]. Individually, front rows started at a higher position than back rows (p = 0.009) and were at a higher vertical position than locks when producing maximum force (p = 0.028). Front rows had lower variation in the CoP (p = 0.044) and less movement to achieve their maximum force (p = 0.020) than locks. Front rows moved less overall than back rows (p = 0.028) during the scrum trial. The design and application of the individual scrum ergometer showed with good limits of agreement that differences in force magnitude and CoP exist within scrummaging players. Practically, the application of this ergometer may assist in the individual optimisation of scrummaging performance.

These findings show that subjective assessments of reflexes using reflex rating scales correlate strongly with biomechanical and electromyographic measures.