Reducing the peak tibial acceleration of running by music-based biofeedback: A quasi-randomized controlled trial

A Review of the Validity and Reliability of Accelerometer-Based Metrics From Upper Back-Mounted GNSS Player Tracking Systems for Athlete Training Load Monitoring

ABSTRACT

Dawson, L, Beato, M, Devereux, G, and McErlain-Naylor, SA. A review of the validity and reliability of accelerometer-based metrics from upper back-mounted GNSS player tracking systems for athlete training load monitoring. J Strength Cond Res 38(8): e459-e474, 2024-Athlete load monitoring using upper back-mounted global navigation satellite system (GNSS) player tracking is common within many team sports. However, accelerometer-based load monitoring may provide information that cannot be achieved with GNSS alone. This review focuses on the accelerometer-based metrics quantifying the accumulation of accelerations as an estimation of athlete training load, appraising the validity and reliability of accelerometer use in upper back-mounted GNSS player tracking systems, the accelerometer-based metrics, and their potential for application within athlete monitoring. Reliability of GNSS-housed accelerometers and accelerometer-based metrics are dependent on the equipment model, signal processing methods, and the activity being monitored. Furthermore, GNSS unit placement on the upper back may be suboptimal for accelerometer-based estimation of mechanical load. Because there are currently no feasible gold standard comparisons for field-based whole-body biomechanical load, the validity of accelerometer-based load metrics has largely been considered in relation to other measures of training load and exercise intensity. In terms of convergent validity, accelerometer-based metrics (e.g., PlayerLoad, Dynamic Stress Load, Body Load) have correlated, albeit with varying magnitudes and certainty, with measures of internal physiological load, exercise intensity, total distance, collisions and impacts, fatigue, and injury risk and incidence. Currently, comparisons of these metrics should not be made between athletes because of mass or technique differences or between manufacturers because of processing variations. Notable areas for further study include the associations between accelerometer-based metrics and other parts of biomechanical load-adaptation pathways of interest, such as internal biomechanical loads or methods of manipulating these metrics through effective training design.

Enhancing running injury prevention strategies with real-time biofeedback: A systematic review and meta-analysis

The number of runners and the incidence of running-related injuries (RRIs) are on the rise. Real-time biofeedback gait retraining offers a promising approach to RRIs prevention. However, due to the diversity in study designs and reported outcomes, there remains uncertainty regarding the efficacy of different forms of feedback on running gait biomechanics. Three databases: MEDLINE, PUBMED, and SPORTDiscus were searched to identify relevant studies published up to March 2024, yielding 4646 articles for review. The quality of the included studies was assessed using the Downs and Black Quality checklist. Primary outcomes, including Peak Tibial Acceleration (PTA), Vertical Average Loading Rate (VALR), and Vertical Instantaneous Loading Rate (VILR), were analysed through meta-analysis. 24 studies met the inclusion criteria and were analysed in this review.17 used visual biofeedback (VB) while 14 chose auditory biofeedback (AB). The meta-analysis revealed a reduction in loading variables both immediately following the intervention and after extended training, with both visual and auditory feedback. Notably, the decrease in loading variables was more pronounced post-training and VB proved to be more effective than AB. Real-time biofeedback interventions are effective in lowering loading variables associated with RRIs. The impact is more substantial with sustained training, and VB outperforms AB in terms of effectiveness.

Cues to land softly and quietly result in acute reductions in ground reaction force loading rates in runners

BACKGROUND

A common gait retraining goal for runners is reducing vertical ground reaction force (GRF) loading rates (LRs), which have been associated with injury. Many gait retraining programs prioritize an internal focus of attention, despite evidence supporting an external focus of attention when a specific outcome is desired (e.g., LR reduction).

RESEARCH QUESTION

Does an external focus of attention (using cues for quiet, soft landings) result in comparable reductions in LRs to those achieved using a common internal focus (forefoot striking while barefoot)?

METHODS

This observational study included 37 injured runners (18 male; mean age 36 (14) years) at the OMITTED Running Center. Runners wore inertial measurement units over the distal-medial tibia while running on an instrumented treadmill at a self-selected speed. Data were collected for three conditions: 1) Shod-Control (wearing shoes, without cues); 2) Shod-Quiet (wearing shoes, cues for quiet, soft landings); and 3) Barefoot-FFS (barefoot, cues for forefoot strike (FFS)). Within-subject variables were compared across conditions: vertical instantaneous loading rate (LR, primary outcome); vertical stiffness during initial loading; peak vertical GRF; peak vertical tibial acceleration (TA); and cadence.

RESULTS

Vertical LR, stiffness, and TA were lower in the Shod-Quiet compared to Shod-Control p < 0.001). Peak vertical GRF and cadence were not different between Shod-Quiet and Shod-Control. Reductions in stiffness and LR were similar between Shod-Quiet and Barefoot-FFS, and GRF in Barefoot-FFS remained similar to both shod conditions. However, runners demonstrated additional reductions in TA and increased cadence when transitioning from Shod-Quiet to the Barefoot-FFS condition (p < 0.05).

SIGNIFICANCE

These results suggests that a focus on quiet, soft landings may be an effective gait retraining method for future research.

Learning effects in over-ground running gait retraining: A six-month follow-up of a quasi-randomized controlled trial

This study evaluated learning and recall effects following a feedback-based retraining program. A 6-month follow-up of a quasi-randomized controlled trial was performed with and without recall. Twenty runners were assigned to experimental or control groups and completed a 3-week running program. A body-worn system collected axial tibial acceleration and provided real-time feedback on peak tibial acceleration for six running sessions in an athletic training facility. The experimental group received music-based biofeedback in a faded feedback scheme. The controls received tempo-synchronized music as a placebo for blinding purposes. The peak tibial acceleration and vertical loading rate of the ground reaction force were determined in a lab at baseline and six months following the intervention to assess retention and recall. The impacts of the experimental group substantially decreased at follow-up following a simple verbal recall (i.e., run as at the end of the program): peak tibial acceleration:-32%, p = 0.018; vertical loading rate:-34%, p = 0.006. No statistically significant changes were found regarding the retention of the impact variables. The impact magnitudes did not change over time in the control group. The biofeedback-based intervention did not induce clear learning at follow-up, however, a substantial impact reduction was recallable through simple cueing in the absence of biofeedback.

Runners' responses to a biofeedback intervention aimed to reduce tibial acceleration differ within and between individuals

An increment in peak tibial acceleration (PTA) may be related to an increased risk of running-rated injury. Many authors believe that reducing PTA through improved shock-absorption could, therefore, help prevent injury. The aim of the current study was, therefore, to investigate the individual responses of participants to a biofeedback intervention aimed at reducing PTA.11 participants (two females, nine males; 43 ± 10 years; stature: 1.74 ± 0.07 m; body mass: 74 ± 11 kg; distance running a week: 19 ± 14 km; 5 km time: 24 ± 3 min) received an intervention of six sessions of multisensory biofeedback aimed at reducing PTA. Mean PTA and kinematic patterns were measured at baseline, directly after the feedback intervention and a month after the end of the intervention. Group as well as single-subject analyses were performed to quantify differences between the sessions. A significant decrease of 26 per cent (effect size: Hedges' g = 0.94) in mean PTA was found a month after the intervention. No significant changes or large effect sizes were found for any group differences in the kinematic variables. However, on an individual level, shock-absorbing solutions differed both within and between participants. The data suggest participants did not learn a specific solution to reduce PTA but rather learned the concept of reducing PTA. These results suggest future research in gait retraining should investigate individual learning responses and focus on the different strategies participants use both between and within sessions. For training purposes, participants should not focus on learning one running strategy, but they should explore several strategies.

The "impacts cause injury" hypothesis: Running in circles or making new strides?

Some of the earliest biomechanics research focused on running and the ground reaction forces generated with each step. Research in running gait accelerated in the 1970's as the growing popularity in running increased attention to the musculoskeletal injuries sustained by runners. Despite decades of high-quality research, running remains the most common cause of exercise-related musculoskeletal injuries and rates of overuse running-related injuries (RRI) have not appreciably declined since the research began. One leading area of running gait research focuses on discrete variables derived from the vertical ground reaction force, such as the vertical loading rate. Across sub-disciplines of running gait research, vertical loading rate is often discussed as the primary and undisputed variable associated with RRI despite only low to moderate evidence that retrospectively or prospectively injured runners generate greater vertical loading rates than uninjured counterparts. The central thesis of this review is that relying on vertical loading rate is insufficient to establish causal mechanisms for RRI etiology. To present this argument, this review examines the history of the 'impacts cause injury' hypothesis, including a historical look at ground reaction forces in human running and the research from which this hypothesis was generated. Additionally, a synthesis of studies that have tested the hypothesis is provided and recommendations for future research are discussed. Although it is premature to reject or support the 'impacts cause injury' hypothesis, new knowledge of biomechanical risk factors for RRI will remain concealed until research departs from the current path or adopts new approaches to previous paradigms.

Healthy Running Habits for the Distance Runner: Clinical Utility of the American College of Sports Medicine Infographic

ABSTRACT

Healthy running form is characterized by motion that minimizes mechanical musculoskeletal injury risks and improves coactivation of muscles that can buffer impact loading and reduce stresses related to chronic musculoskeletal pain. The American College of Sports Medicine Consumer Outreach Committee recently launched an infographic that describes several healthy habits for the general distance runner. This review provides the supporting evidence, expected acute motion changes with use, and practical considerations for clinical use in patient cases. Healthy habits include: taking short, quick, and soft steps; abdominal bracing; elevating cadence; linearizing arm swing; controlling forward trunk lean, and; avoiding running through fatigue. Introduction of these habits can be done sequentially one at a time to build on form, or more than one over time. Adoption can be supported by various feedback forms and cueing. These habits are most successful against injury when coupled with regular dynamic strengthening of the kinetic chain, adequate recovery with training, and appropriate shoe wear.

Sensor-based gait training to reduce contact time for runners with exercise-related lower leg pain: a randomised controlled trial

Objectives

To assess the effects of a 4-week randomised controlled trial comparing an outdoor gait-training programme to reduce contact time in conjunction with home exercises (contact time gait-training feedback with home exercises (FBHE)) to home exercises (HEs) alone for runners with exercise-related lower leg pain on sensor-derived biomechanics and patient-reported outcomes.

Design

Randomised controlled trial.

Setting

Laboratory and field-based study.

Participants

20 runners with exercise-related lower leg pain were randomly allocated into FBHE (4 male (M), 6 female (F), 23±4 years, 22.0±4.3 kg/m²) or HE groups (3 M, 7 F, 25±5 years, 23.6±3.9 kg/m²).

Interventions

Both groups completed eight sessions of HEs over 4 weeks. The FBHE group received vibrotactile feedback through wearable sensors to reduce contact time during outdoor running.

Primary and secondary outcome measures

Patient-reported outcome measures (PROMs) and outdoor gait assessments were conducted for both groups at baseline and 4 weeks. PROMs were repeated at 6 weeks, and feedback retention was assessed at 6 weeks for the FBHE group. Repeated measures analyses of variance were used to assess the influence of group and timepoint on primary outcomes.

Results

The FBHE group reported increased function and recovery on PROMs beyond the HE group at 6 weeks (p<0.001). There was a significant group by time interaction for Global Rating of Change (p=0.004) and contact time (p=0.002); the FBHE group reported greater subjective improvement and reduced contact time at 4 and 6 weeks compared with the HE group and compared with baseline. The FBHE group had increased cadence (mean difference: 7 steps/min, p=0.01) at 4 weeks during outdoor running compared with baseline.

Conclusion

FBHE was more effective than HE alone for runners with exercise-related lower leg pain, manifested with improved PROMs, reduced contact time and increased cadence.

Trial registration number

NCT04270565.

Biomechanical adaptations following a music-based biofeedback gait retraining program to reduce peak tibial accelerations

PURPOSE

The present study aimed to determine whether runners can reduce impact measures after a six-session in-the-field gait retraining program with real-time musical biofeedback on axial peak tibial acceleration (PTA_a ) and identify the associated biomechanical adaptations.

METHODS

Twenty trained high-impact runners were assigned to either the biofeedback or the music-only condition. The biofeedback group received real-time feedback on the PTA_a during the gait retraining program, whereas the music-only condition received a sham treatment. Three-dimensional gait analysis was conducted in the laboratory before (PRE) and within one week after completing the gait retraining program (POST). Subjects were instructed to replicate the running style from the last gait retraining session without receiving feedback while running overground at a constant speed of 2.9 m∙s^-1 .

RESULTS

Only the biofeedback group showed significant reductions in both PTA_a (∆x̅ = -26.9%, p = 0.006) and vertical instantaneous loading rate (∆x̅ = -29.2%, p = 0.003) from PRE to POST. In terms of biomechanical adaptations, two strategies were identified. Two subjects transitioned toward a more forefoot strike. The remaining eight subjects used a pronounced rearfoot strike and posteriorly inclined shank at initial contact combined with less knee extension at toe-off while reducing vertical excursion of the center of mass.

CONCLUSIONS

After completing a music-based biofeedback gait retraining program, runners can reduce impact while running overground in a laboratory. We identified two distinct self-selected strategies used by the participants to achieve reductions in impact.