Pinfold et al. – Descriptive Analysis of Linear and Angular Acceleration Forces Experienced at the Head During a Simulated Front-on Rugby Union Tackle

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AIM

To explore the head acceleration profile of forwards and backs during a simulated front-on rugby tackle

METHODS

Forty-one rugby union players each performed 10 tackles (5 left and 5 right) against a 50kg bag traveling at a speed of 4.2m/s. Formalized instructions were provided to standardize the procedure and technique. During each tackle a CSx Head Positioning Unit was worn behind the ear. The sensor recorded linear (4000Hz) and angular head acceleration (3200Hz) over a 15ms period for all impacts exceeding a 10g threshold.

RESULTS

Peak linear and rotational acceleration values of 88±51g and 2403±604rad/s were observed for the backs. For the forwards peak linear values of 91±48g and rotational acceleration of 2560±530rad/s were documented. The reliability of the acceleration forces produced during the tackle were poor for both linear (ICC=0.21) and rotational (ICC=0.22) acceleration. No meaningful correlations (p≥0.05) were observed between the anthropometric variables and concussion history or the acceleration forces recorded at the head.

CONCLUSIONS

In the current study the peak linear acceleration experienced at the head was 87g, which is somewhat higher than what has been reported in tackle simulation in American football. Further investigation into head acceleration during game play is needed and in particular during the tackle situation.

2 thoughts on “Pinfold et al. – Descriptive Analysis of Linear and Angular Acceleration Forces Experienced at the Head During a Simulated Front-on Rugby Union Tackle

  1. Hi Dario

    Thanks so much for your questions really appreciate the time you have taken to look through our work.

    1) Once the 10g threshold was reached the accelerometer recorded acceleration for a period of 18.75ms; 3.75 ms is recorded before the data collection trigger and 15 ms of data is collected after the threshold trigger. This duration is based on the recommended head injury criterion duration window. We reported area under the curve for both the resultant linear and rotational acceleration variables as a composite measure of the duration and acceleration experienced at the head.

    It is likely that the higher linear acceleration values achieved in our study are a reflection of the velocity of the participant when they made contact with the bag. They performed a 3 m run-up prior to contact and were instructed to hit the bag as hard as possible, which likely explains the difference in head acceleration and the variability we observed between trials.

    2) All trials were recorded at 600 Hz with a high speed camera, we used Kinovea to calculate the resultant linear velocity of the bag. The average resultant linear velocity was taken over six time points at the point of impact. We are currently working towards calculating the angular acceleration of the boxing bag and can get back to you with a response on this question.

    3) The 10g threshold used in this study was consistent with what has been presented in other research primarily in American gridiron.

    4) We were primarily interested to observe the correlations between the head acceleration profile and the neck strength of the participants. We are still in the process of analysing this data but hope to have some results soon. We did not place an accelerometer on the bag.

    Happy to chat further thanks so much.

    Cheers
    Jayden

    Like

  2. Hi Jayden!
    Cool poster! I have got few questions for you:
    1) What’s the average duration of the impact? Is it 15 ms? It looks like you measured very high linear acceleration values (from 66 g to 81 g). We run a simular study (same punching bag speed) and we measured head acceleration (accelerometer placed on nasium, so frontal aspect of the head) closer to 20 g. Why do you think you measured such high values?
    2) How did you measure peak velocity of the punching bag? My understanding is that the punching bag had both a linear and angular acceleration..is that true?
    3) I am interested in the 10 g threshold. Is there a paper showing how this threshold has been calculated?
    4)How did you estimate tackle force? Did you place an accelerometer on the bag too?

    Thanks!

    Dario

    Like

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