Navigation

Bicycle helmets highly effective at preventing cyclist’s head injury

Bicycle helmets are highly effective at preventing head injury

A validated anthropomorphic test headform of a bicycle helmet/no bicycle helmet

Bicycle helmets are highly effective at preventing head injury during impact is the finding of a recent study published in Accident Analysis & Prevention. In this study the authors performed biomechanical testing of paired helmeted and unhelmeted head impacts using a validated anthropomorphic test headform and a range of drop heights between 0.5 m and 3.0 m, while measuring headform acceleration and Head Injury Criterion (HIC). That is they didn’t actually smack cyclist’s head into the concrete (even if some would like that) but instead used a mechanical testing device to test the effectiveness of helmets to prevent head injury. Note carefully what is begin tested here … the specific effectiveness of helmets to prevent head injuries … cyclists die from other injuries which a helmet will not protect against.

The paper arising from the study has been published in the journal, Accident Analysis and Prevention.

The Key Conclusion – Bicycle Helmets Protect Cyclists’ Heads Study

In the abstract of the paper the authors report ..

In the 2 m (6.3 m/s) drops, the middle of our drop height range, the helmet reduced peak accelerations from 824 g (unhelmeted) to 181 g (helmeted) and HIC was reduced from 9667 (unhelmeted) to 1250 (helmeted). At realistic impact speeds of 5.4 m/s (1.5 m drop) and 6.3 m/s (2.0 m drop), bicycle helmets changed the probability of severe brain injury from extremely likely (99.9% risk at both 5.4 and 6.3 m/s) to unlikely (9.3% and 30.6% risk at 1.5 m and 2.0 m drops respectively). These biomechanical results for acceleration and HIC, and the corresponding results for reduced risk of severe brain injury show that contemporary bicycle helmets are highly effective at reducing head injury metrics and the risk for severe brain injury in head impacts characteristic of bicycle crashes.
Overtaking proximities were not related to a bicyclist’s apparent experience level.

Key Conclusions from the Bicycle Helmets Protect Cyclists’ Heads Study

Below is a sample of quotes from the paper highlighting the findings of the study. A full read of the paper is warranted to get more complete understanding.

  • The study characterised the ability of a typical contemporary bicycle helmet to reduce the severity of a head impact and reduce the risk of severe life-threatening skull and brain injury, compared to not wearing a helmet, in matched impact tests where impact severities (i.e. drop height and pre-impact head velocity) were identical for the case of the helmeted and unhelmeted headform.
  • The tested helmet dramatically decreased peak linear head acceleration (Fig. 3), HIC15 (Fig. 4) and the potential for severe brain injury (Fig. 5) in all impacts
  • In drops from 2.0 m up to 3.0 m, the helmeted headform experienced accelerations above the IARV, but helmeted headform accelerations were at least 4 times smaller than those of the unhelmeted headform
  • Considering a realistic bicycle accident scenario documented in the literature (Fahlstedt et al., 2012) where a cyclist was thrown at 20 km/h (i.e. 5.6 m/s which corresponds to a drop height of approximately 1.5 m), our analysis indicates that a helmeted cyclist in this situation would have a 9% chance of sustaining the severe brain and skull injuries noted above whereas an unhelmeted cyclist would have sustained these injuries with 99.9% certainty. In other words, a helmet would have reduced the probability of skull fracture or life threatening brain injury from very likely to highly unlikely.

Bicycle Helmets Protect Cyclists’ Heads Study – The Abstract

Cycling is a popular form of recreation and method of commuting with clear health benefits. However, cycling is not without risk. In Canada, cycling injuries are more common than in any other summer sport; and according to the US National Highway and Traffic Safety Administration, 52,000 cyclists were injured in the US in 2010. Head injuries account for approximately two-thirds of hospital admissions and three-quarters of fatal injuries among injured cyclists. In many jurisdictions and across all age levels, helmets have been adopted to mitigate risk of serious head injuries among cyclists and the majority of epidemiological literature suggests that helmets effectively reduce risk of injury. Critics have raised questions over the actual efficacy of helmets by pointing to weaknesses in existing helmet epidemiology including selection bias and lack of appropriate control for the type of impact sustained by the cyclist and the severity of the head impact. These criticisms demonstrate the difficulty in conducting epidemiology studies that will be regarded as definitive and the need for complementary biomechanical studies where confounding factors can be adequately controlled. In the bicycle helmet context, there is a paucity of biomechanical data comparing helmeted to unhelmeted head impacts and, to our knowledge, there is no data of this type available with contemporary helmets. In this research, our objective was to perform biomechanical testing of paired helmeted and unhelmeted head impacts using a validated anthropomorphic test headform and a range of drop heights between 0.5 m and 3.0 m, while measuring headform acceleration and Head Injury Criterion (HIC). In the 2 m (6.3 m/s) drops, the middle of our drop height range, the helmet reduced peak accelerations from 824 g (unhelmeted) to 181 g (helmeted) and HIC was reduced from 9667 (unhelmeted) to 1250 (helmeted). At realistic impact speeds of 5.4 m/s (1.5 m drop) and 6.3 m/s (2.0 m drop), bicycle helmets changed the probability of severe brain injury from extremely likely (99.9% risk at both 5.4 and 6.3 m/s) to unlikely (9.3% and 30.6% risk at 1.5 m and 2.0 m drops respectively). These biomechanical results for acceleration and HIC, and the corresponding results for reduced risk of severe brain injury show that contemporary bicycle helmets are highly effective at reducing head injury metrics and the risk for severe brain injury in head impacts characteristic of bicycle crashes.

The full reference for the paper is:

Cripton, P. A., Dressler, D. M., Stuart, C. A., Dennison, D. R. (2014). Bicycle helmets are highly effective at preventing head injury during head impact: Head-form accelerations and injury criteria for helmeted and unhelmeted impacts. Accident Analysis and Prevention, 70, 1-7.

Other studies related to bicycle helmets are listed in the Cycling Research page.

No comments yet.

Please share your thoughts ...

%d bloggers like this: