Do Niggles Matter? Injury Surveillance is a Key Step in the Prevention of Injuries

DO NIGGLES MATTER?

INJURY SURVEILLANCE IS A KEY STEP IN THE PREVENTION OF INJURIES

FEATURE / DR MATT WHALAN

It has long been acknowledged that injury surveillance is the cornerstone for the development of effective injury prevention programs and systems (Van Mechelen et al, 1992). Without injury surveillance it is difficult to not only determine what injuries you need to target but also, surveillance ensures that your intervention is effective. Most commonly in football injury research, however, only time-loss injuries which result in a failure to fully participate in training or matches are used to determine injury incidence and severity, based on the football injury recording consensus statement (Fuller et al, 2006). As such, injuries or physical complaints that do not stop a player training or playing, non-time loss injuries or “niggles”, are not routinely reported in the literature or if they are, it is only when the injury is significant enough to impact on participation. Clarsen and Bahr (2014a) produced an excellent figure which outlines the different definitions applied to injury classification (Figure 1). As seen in this figure, the time loss definition captures many but not all injuries that can occur to a player with the “niggle zone” previously not addressed in football injury research.

The Oslo Sport Trauma Research Centre (OSTRC) Questionnaire on Health Problems for Self-Reporting Injuries.

Developed in 2014 by Assoc Prof Ben Clarsen and colleagues, the OSTRC Questionnaire on Health Problems was developed to try and improve injury data collection methods across a number of sports. The survey was sent out once a week and explored the impact of any physical issue during the week on participation, performance, pain perception and training volume (Figure 2). More recently, other versions of the survey have been used to capture locationspecific (e.g. hip/groin) non-time loss injury information with much larger capture of physical issues compared with the traditional time loss method (Harøy et al 2017).

Figure 1 - Adapted figure from Clarsen and Bahr (2014a) highlighting different classifications of injury. The consensus for injury recording in football (Fuller et al, 2006) covers the time loss injury portion, while the OSTRC Questionnaire on Health Problems (Clarsen et al, 2014b) endeavours for a much larger injury capture. The Niggle Zone is the missing piece in football injury surveillance.

Figure 2 - The OSTRC Questionnaire on Health Problems (Clarsen et al, 2014b) explores the impact of physical complaints on 4 categories – participation, volume, performance and perception of severity.

The Research

Our research questions – how many niggles occur in football & can a niggle help identify a player at an increased risk of a time-loss injury? Based on the emerging research and from most practitioners’ own experience, it is likely that time loss injury rates significantly underestimate the prevalence of physical complaints in football. Furthermore, little was also known about the prevalence and impact niggles in football may have on more serious time loss injury risk. As such, we looked to capture both time loss and non-time loss (niggles) injuries over an entire season and explore the concept of injury risk.

What Did We Do?

Players from semi-professional football clubs in Australia agreed to participate in an injury study during the 2016 season (35 weeks). All players participated in football exposures 3-4 times per week and had any time loss (medical staff recorded via the Football Consensus injury

method) and non-time loss (self-reported via the OSTRC Questionnaire on Health Problems) injuries recorded. To be included for analysis, players were required to complete at least 70% of all weekly surveys.

What Did We Find?

Injuries and Weekly Injury Prevalence The total number of reported “physical complaints” was 2.3 times greater when selfreported (OSTRC Questionnaire) compared with a medical reported injury. However, for a number of potential reasons, time loss injury capture was much greater using the traditional injury recording methods. Each week, on average, niggles accounted for 28% of all weekly injuries with time-loss injuries accounting for 5% when recorded by the OSTRC Questionnaire (Figure 3). Interestingly, combining both methods, with niggles and time-loss injuries recorded by medical staff, a staggering 49% of players were affected by an injury each week.

The Risk of a Time Loss Injury Within 7 days of Reporting a Niggle Risk of an injury for a player that reported a niggle was calculated and assessed relative to the normal risk of sustaining an injury. As can be seen in Figure 4, when a player reported a minor or moderate physical complaint but was still able to participate in football, the risk of sustaining a time-loss injury within 7 days was 3.6 to 6.9x higher when preceded by ‘minor’ and ‘moderate’ niggle, respectively. The greater the impact the niggle had on player perceived participation, severity, performance or volume, the higher the risk was determined to be.

Does the location of a niggle matter? Importantly, 68% of all time-loss (TL) injuries were preceded by a niggle report, with 94% of knee and 90% of hamstring time loss injuries preceded by a niggle in the same location. The most common injury locations were the hamstring muscles and knee. The greatest risks were observed in the ankle and lower leg with variation observed across regions (Figure 5). Of note, the hip/groin and lower back were associated with the highest niggles to time loss injury ratio indicating that perhaps players are much more likely to continue to play on with these prevalent issues.

So……Should We Bother Recording Niggles?

Yes! For 2 very good reasons: One – in this study, over a quarter of players are affected by a non-time loss niggle each week with more than 2x the number of niggles to time-loss injuries. Players consistently reported that they perceived that these niggles impacted on their performance and should be of as much interest to performance staff as the medical staff. When designing injury prevention systems, taking into consideration the type and volume of reported niggles may be useful in directing intervention strategies.

Figure 3 - Weekly prevalence of niggles (black) and time-loss injury (orange) as recorded by the OSTRC Questionnaire on Health Problems.

Figure 4 - Associated injury risk of sustaining a time-loss injury following a niggle report for all 4 categories in the OSTRC Questionnaire on Health Problems. (adapted from an infographic by Adam Virgile; adamvirgile.com)

Figure 5 - The influence of location of a niggle report on the relative risk (RR) and prevalence of niggles compared to time loss injury (Niggle: Time Loss) for the most common injury sites in football.

Two – the presence of a niggle may help performance and medical staff to identify players at increased risk of injury. The major point that needs to be made though is that the presence of a niggle should not be used to predict if a player is going to obtain a time loss injury. The false-positive was high (low sensitivity) in this study i.e. many players that reported a niggle never had a time-loss injury in the following 7 days! As such, a niggle report can potentially be used to flag a player at risk and stimulate a conversation with the player. From this conversation or assessment, adjustments if necessary, can be performed. On the other hand, the findings potentially suggest that not all niggles are created equal. Some players may continue to play with niggling hip/groin or lower back issues however are less likely with a hamstring or lower leg complaint.

Translating these Findings into the Real World

To record non-time loss injuries a number of things need to happen and are included in the “Niggles Checklist” (Figure 6). Firstly, the context of injury reporting matters a great deal (Bolling et al, 2018). Players need to trust the medical, performance and technical staff enough to feel comfortable to report niggles. If players think they will be “punished” or viewed as being an over-reporter then players will be less likely to volunteer this information. As such, understanding what motivates players or what they consider to be an injury is important as is educating players on the importance of reporting.

Secondly, medical staff need to work hard with performance and technical staff to create a “safe” environment for players to report niggles. For example, let us take the case of a player who reports an issue with their hip/groin at pre-training monitoring but believes they can continue to participate in training. In this scenario, a strategy for the medical staff is to ensure they understand or know what the training session for the day entails. Following this, discussion with the performance and technical staff may result in a slight modification of volume for the player e.g. reduced volume of crossing in a session, however, the player can continue to participate in the session. The overall result is then that the player participates, all stakeholders are informed of the increased risk, small modifications can be easily implemented and the session integrity is maintained.

Thirdly, education of all stakeholders regarding injury risk context is vital. When a coach or medical staff hears that a player is 3x more likely to get an injury due to a slight niggle, then a reaction could be to always err on the side of caution and not allow a player to participate. Of course, if a player doesn’t play or train then their risk of injury is zero, but that is unlikely to be a sustainable long-term strategy! A simple way to overcome this is to reference risk to the normal risk of sustaining an injury when nothing is wrong i.e. the normal risk in this study was 10%. Therefore, a player with a slight niggle now may have a 30% risk of sustaining an injury but a 70% chance that nothing happens. Additionally, when considering the high false-positive rate, it is easier to place appropriate caution to the restricting player participation. Overall, much of the implementation and adoption of reporting niggles requires excellent communication and respect from all stakeholders and planning.

Considerations for Future Research

• It’s important to note that this is the first study to investigate the impact of niggles on time loss injury risk. Further research is required to determine whether similar findings are consistent across different levels i.e. professional vs semi-professional, however, based on clinical experience it is suspected there will continue to be a benefit to encouraging the reporting and recording of niggles.

• Getting players to consistently complete the OSTRC Questionnaire was difficult over an extended period of time with only 33% consistently completing the questionnaire. Potentially reducing the questionnaire to just one or two sections e.g. participation and performance, may reduce the time to complete it and potentially incorporating the survey into post-session reporting along with RPE may also assist with workflow.

• Investigating the best option(s) to deal with a reported niggle is essential. For example, if a player reports hamstring tightness, and physical therapy intervention is applied, e.g. soft tissue therapy, and the niggle resolves, does the player’s risk reduce? Or perhaps modification or manipulation of training load is enough.

Key Findings • Collecting information regarding non-time loss complaints - “niggles” - provides a more in-depth picture of player health status and should be standard medical staff practice.

• Over a quarter of players, on average, reported a niggle each week that did not affect their participation in training or a match, but had a self-perceived impact on their performance.

• The risk of a time loss injury is 3.6-6.9 x higher when preceded by a niggle. In fact, 68% of all time loss injuries were preceded by a niggle report, with 94% of knee and 90% of hamstring time loss injuries preceded by a niggle in the same location.

• Due to a high false positive rate, the presence of a niggle alone should not be used as a prediction tool. A niggle may be a useful secondary injury prevention strategy to flag players at increased risk of injury and open player, coach and medical staff communication.

Figure 6 - Niggles Checklist to assist medical, performance and technical staff to translate findings into practice.

Dr Matt Whalan Twitter: @FigtreePhysio

Acknowledgements

Dr John Sampson and Associate Professor Ric Lovell were integral parts of this research project. Article Reference: Whalan M, Lovell R, Sampson JA. Do Niggles Matter? – Increased injury risk following physical complaints in football (soccer). Science and Medicine in Football 2020; 4:3, 216-224, DOI: 10.1080/24733938.2019.1705996.

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