Biofeedback for better running technique?

Can wearable biofeedback devices improve running technique and efficiency? Sports Performance Bulletin looks at new research

The past four decades has seen an explosion in running shoe technology, with successive generations of shoes using increasingly sophisticated solutions to help improve running gait and reduce impact forces, which are a particular problem when pounding the tarmac or pavements. You might expect therefore that with better running gaits and superior cushioning, the rate of injury suffered by runners per mile run has been steadily falling. However, studies conducted from 1989 to the present have found a remarkably consistent rate of running gait-related injury problems⁽¹⁾.

One possible reason is that some of the technologies used to improve gait and reduce foot-strike impact may actually be somewhat counterproductive. For example, research suggests that the impact forces during foot strike may actually serve as input signals, which help produce ‘muscle tuning’ shortly before the next contact with the ground⁽²⁾. This tuning appears to help to minimize soft-tissue vibration and/or reduce joint and tendon loading. In other words, increasing cushioning and reducing foot strike impact interferes seems to interfere with the body’s ability to alter and adapt its neuromuscular response and maintain its preferred joint movement path for a given movement task, which effectively results in a less than optimal running gait, poorer running efficiency and no significant reduction in injury risk.

Some researchers have argued a better approach for runners is to undertake ‘gait retraining’, using for example, wearable biofeedback devices. These types of devices monitor parameters such as stride length and frequency, lateral sway, vertical deceleration and rotational forces and give feedback to the athlete in real time so he/she can adapt running style/gait and improve running biomechanics accordingly. But does gait retraining using biofeedback work, and if so, how effective is it?

The research

To try and answer this question, a team of Australian scientists has just published a systematic review paper in the journal ‘Sensors’ [Sensors (Basel). 2020 Nov 19;20(22):E6637. doi: 10.3390/s20226637]. The team searched databases for peer-reviewed articles published between March 2009 and March 2020 that evaluated the effects of wearable devices with biofeedback on the biomechanics of running. Only articles focusing on healthy uninjured runners were included, and which were confined to running biomechanics (limb movements and gait). Nineteen articles met the inclusion criteria and were subsequently analyzed.

The findings

The main findings were as follows:

• Most studies reported a significant reduction in positive peak acceleration – a parameter that is known to be related to tibial stress fractures in running.
• There was good evidence that biofeedback devices were useful for increasing stride frequencies (and therefore shortening stride lengths). This produced benefits in terms of reduced vertical loading in the knee and ankle joints, reduced vertical displacement of the body and increased knee flexion. In plain English, this translates to less ‘up-down bobbing’ when running, or to put it another way, a more efficient ‘horizontal gliding motion’ when viewing the running gait from a side angle.
• When info on ground contact time and speed were fed back to runners, this tended to reduce running times and increase swing phase times. Put simply, runners tended to spend more time ‘airborne’ in between ground strikes, leading to a more efficient running gait.

Practical implications

 These findings suggests that biofeedback devices aimed at improving biomechanics in runners can provide valuable gains in performance, along with a reduced injury risk. Athletes and their coaches who are interested in trialing these devices should look for the types of technologies studied in the literature. These devices principally use accelerometers (both wired and non-wired). These can be uniaxial, biaxial or triaxial accelerometers (ie detecting acceleration in all three dimensions). Of these, devices using triaxial accelerometers appear to provide the most solid evidence for their use. Some studies used inertial motion units, which contained triaxial accelerometers together with triaxial magnetometers and gyroscopes. These devices can be worn as ankle straps, sewn into socks or as integral components of a running shoe (eg Altra IQ).

References

1. JAMA. 2011;101(3):231-46
2. Clin J Sport Med. 2001 Jan;11(1):2-9