The calibration and application of an individual scrummaging ergometer

Abstract

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.

Force Production during the Sustained Phase of Rugby Scrums: A Systematic Literature Review

“…Participants ranged in mean age from 16.6 to 34 years old, with the majority in their early 20s. Twelve studies used the full pack [3,4,[7][8][9]12,14,15,[21][22][23][24], while fourstudies used the front row [11,25,26] and two used the tight five only [10,13]. Two studies recruited a mix of forwards and backs (Dobbs 2017;Wu et al 2006) [27].…”

“…Most of the studies (n = 21) had players scrum against a scrum machine [4,8,[10][11][12][13][14][15][17][18][19][20][21][22][23][24][25][26]28,29,31].…”

“…Nine studies had players perform scrums on natural grass turf [3,7,9,10,13,18,[21][22][23], three used synthetic turf [11,24,29], two used rubber matting [12,14], and three were done indoors on lab or track floors [20,28,30]. One study had participants stand on a force plate, which the researchers had put skateboard tape on to reduce slippage [27].…”

“…Few studies provided details on the warm up used. Most studies utilized a general selfselected or coach-directed warm up (presumably of dynamic activities like high knees, butt kickers, jogging, etc) [3,4,9,10,15,23,25], and some studies provided athletes with warm up pushes on the scrum machine in addition to or instead of a general dynamic warm up [3,4,9,14,15,20,23,24,[27][28][29].…”

A review of the biomechanical determinants of rugby scrummaging performance

“…Scrum kinetics have been used as the major objective scientific measure of scrummaging performance. Various methods have been employed to quantify this which include: instrumented scrum machines [11][12][13][14][15][16] , force platforms [17] , and shoulder mounted pressure transducers. [18][19][20] Force components The force exerted in the scrum is composed of compressive, lateral and vertical forces.…”