Michael Nunns

Biomechanical characteristics of barefoot footstrike modalities

Barefoot running has increased in popularity over recent years, with suggested injury risk and performance benefits. However, despite many anecdotal descriptions of barefoot running styles, there is insufficient evidence regarding the specific characteristics of barefoot running. The present study provided reference data for four footstrike modalities adopted across a large cohort of habitually shod male runners while running barefoot: heel strikers (HS), midfoot strikers (MS), forefoot strikers (FS) and a newly defined group, toe runners (TR - contact made only with the forefoot), compared with the three modalities previously reported. Plantar pressure analysis was used for the classification of footstrike modality, with clearly distinguishable pressure patterns for different modalities. In the present study, the distribution of footstrike types was similar to that previously observed in shod populations. The absence of differences in ground contact time and stride length suggest that potential performance benefits of a non-HS style are more likely to be a function of the act of running barefoot, rather than of footstrike type. Kinematic data for the knee and ankle indicate that FS and TR require a stiffer leg than HS or MS, while ankle moment and plantar pressure data suggest that a TR style may put greater strain on the plantar-flexors, Achilles tendon and metatarsal heads. TR style should therefore only be adopted with caution by recreational runners. These findings indicate the importance of considering footstrike modality in research investigating barefoot running, and support the use of four footstrike modalities to categorise running styles.

Effects of a seven-week minimalist footwear transition programme on footstrike modality, pressure variables and loading rates

Purpose: The aim was to compare footstrike modality and kinetics pre and post a seven week minimalist footwear transition programme. Methods: Ten recreational athletes (mass: 78.6 (8.7) kg, height: 179.4 (7.6) cm, age: 21.0 (0.7) years) performed overground running trials (3.8 m·s−1) whilst barefoot (BFT), minimal shod (MS) and shod (SH) both pre and post the programme. Ground reaction force and pressure data were simultaneously recorded for all footwear conditions. Footstrike modality was determined via visual inspection of the pressure distribution. Peak impact force, loading rate and peak regional pressures and impulses were compared pre and post, and between footwear conditions. The transition programme comprised of a two-week foot strengthening period followed by a five-week running transition. Results: Post transition there was a general trend for runners to adopt a more anterior footstrike in all three conditions. Additionally, loading rates and several peak pressures and impulses were found to decrease after the transition programme, with region specific changes evident for the effect of footwear. Furthermore, loading rates were higher whilst BFT and MS (instantaneous loading rates pre transition of 446.0 and 379.3 BW·s−1, respectively) compared to SH (105.8 BW·s−1). Conclusion: Whilst a seven-week MS transition programme was shown to decrease several kinetic variables, it was evident that both BFT and MS led to greater loading rates and peak pressures than SH running.

High medial plantar pressures during barefoot running are associated with increased risk of ankle inversion injury in Royal Marine recruits

BACKGROUND Ankle inversion injury is common in military populations but associated biomechanical risk factors are largely unknown. This prospective study examined the association between pressure and kinematic variables, and ankle inversion injury risk in Royal Marine (RM) recruits. It was hypothesised that a more medially concentrated pressure at the heel-off phase of stance, greater impulse and peak pressure at the first metatarsal head, greater peak rearfoot eversion angle and greater eversion excursion would be associated with ankle inversion injury. METHODS Data from 145 male, injury-free RM recruits were recorded in week-2 of a 32-week military training programme. Each recruit completed five running trials at 3.6 ms(-1), along a 2m pressure plate. Kinematic data were simultaneously recorded. Injuries sustained during the training programme were prospectively recorded. FINDINGS Data from eleven recruits who had suffered an ankle inversion injury during RM training were compared with 20 uninjured controls. The injury group displayed a higher (P<0.05) peak first metatarsal pressure, peak metatarsal impulse and more medially concentrated pressure at heel-off than control recruits. There were no differences in kinematic variables between groups. The injury group had a lower body mass than controls (P<0.05). INTERPRETATIONS The findings from this study support existing literature, providing evidence that high medial concentration of vertical forces when running are associated with increased ankle inversion injury risk. This may be due to the lateral ankle ligaments being less accustomed to loading, resulting in relatively weak lateral ligaments, or ligaments less able to deal with fatigue than those of the control group.

The effects of standard issue Royal Marine footwear on risk factors associated with third metatarsal stress fractures

Purpose: The relatively high incidence rate of third metatarsal (MT3) stress fractures in Royal Marine (RM) recruits may be linked to the footwear worn during training. The present study investigated the effect of standard issue RM recruit footwear on biomechanical variables linked with MT3 stress fracture risk. Methods: Seven male volunteers (age 18.3 ± 0.4 years, mass 81.1 ± 8.2 kg) ran at 3.6 m s−1 in a laboratory while wearing a combat assault boot (CAB) and a neutral gym trainer (GT). In-shoe plantar pressure was assessed using pressure insoles (RSScan, 500 Hz). Two-dimensional ankle kinematics and kinetics were assessed at 120 Hz (Peak Motus). Horizontal ground reaction force characteristics were investigated using an AMTI force plate (960 Hz). Results: Peak plantar pressure, impulse and loading rate were significantly greater at the MT3 head in the CAB (P < 0.05). Further significant differences with the CAB were a smaller and earlier peak ankle dorsiflexion, a later heel-off, and greater magnitude...

Four biomechanical and anthropometric measures predict tibial stress fracture: A prospective study of 1065 Royal Marines

Background Tibial stress fractures (TSFs) cause a significant burden to Royal Marines recruits. No prospective running gait analyses have previously been performed in military settings. Aim We aimed to identify biomechanical gait factors and anthropometric variables associated with increased risk of TSF. Methods 1065 Royal Marines recruits were assessed in week 2 of training. Bilateral plantar pressure and three-dimensional lower limb kinematics were obtained for barefoot running at 3.6 m/s, providing dynamic arch index, peak heel pressure and lower limb joint angles. Age, bimalleolar breadth, calf girth, passive hip internal/external range of motion and body mass index (BMI) were also recorded. 10 recruits who sustained a TSF during training were compared with 120 recruits who completed training injury-free using a binary logistic regression model to identify injury risk factors. Results 4 variables significantly (p<0.05) predicted increased risk of TSF (ORs and 95% CI): smaller bimalleolar width (0.73, 0.58 to 0.93), lower BMI (0.56, 0.33 to 0.95), greater peak heel pressure (1.25, 1.07 to 1.46) and lower range of tibial rotation (0.78, 0.63 to 0.96). Summary Reduced impact attenuation and ability to withstand load were implicated in tibial stress fracture risk.

Boot-insole effects on comfort and plantar loading at the heel and fifth metatarsal during running and turning in soccer

Abstract Plantar loading may influence comfort, performance and injury risk in soccer boots. This study investigated the effect of cleat configuration and insole cushioning levels on perception of comfort and in-shoe plantar pressures at the heel and fifth metatarsal head region. Nine soccer academy players (age 15.7 ± 1.6 years; height 1.80 ± 0.40 m; body mass 71.9 ± 6.1 kg) took part in the study. Two boot models (8 and 6 cleats) and two insoles (Poron and Poron/gel) provided four footwear combinations assessed using pressure insoles during running and 180° turning. Mechanical and comfort perception tests differentiated boot and insole conditions. During biomechanical testing, the Poron insole generally provided lower peak pressures than the Poron/gel insole, particularly during the braking step of the turn. The boot model did not independently influence peak pressures at the fifth metatarsal, and had minimal influence on heel loads. Specific boot-insole combinations performed differently (P < 0.05). The 8-cleat boot and the Poron insole performed best biomechanically and perceptually, but the combined condition did not. Inclusion of kinematic data and improved control of the turning technique are recommended to strengthen future research. The mechanical, perception and biomechanical results highlight the need for a multi-faceted approach in the assessment of footwear.

Boot-insole effects on heel and fifth metatarsal loading for running and turning in soccer

Playing surface and footwear are two of the risk factors associated with injuries in soccer (Frey 2003). Footwear worn for soccer tend to be low profile, reducing the likelihood of ankle inversion injuries but providing very little cushioning. Any material cushioning tends to be through a thin cushioning insole, with the material and thickness of this varying for different boot models. Thus when developing a boot, a choice must be made regarding the material and thickness of insole. Overuse injuries such as Achilles tendon pathology, lower back pain and stress fracture of the foot are prevalent in soccer (Paavola et al. 2002). The high loads occurring at heel impact have been linked with many of these overuse injuries. In addition, the reported high incidence of fifth metatarsal fracture may be associated with repeated loading of the forefoot, leading to a weakening of this structure and thus susceptibility to fracture. Therefore, soccer boot design may benefit from provision of cushioning in the heel and the forefoot. The aim of this study was to investigate the influence of two insole types on cushioning when placed within two soccer boot models. The influence on heel and fifth metatarsal loading was investigated.

Effectiveness of non-pharmacological interventions to reduce procedural anxiety in children and adolescents undergoing treatment for cancer: a systematic review and meta-analysis.

Children and young people (CYP) with cancer undergo painful and distressing procedures. We aimed to systematically review the effectiveness of nonpharmacological interventions to reduce procedural anxiety in CYP.

Prospective study of biomechanical risk factors for second and third metatarsal stress fractures in military recruits

OBJECTIVES This prospective study investigated anatomical and biomechanical risk factors for second and third metatarsal stress fractures in military recruits during training. DESIGN Prospective cohort study. METHODS Anatomical and biomechanical measures were taken for 1065 Royal Marines recruits at the start of training when injury-free. Data included passive range of ankle dorsi-flexion, dynamic peak ankle dorsi-flexion and plantar pressures during barefoot running. Separate univariate regression models were developed to identify differences between recruits who developed second (n=7) or third (n=14) metatarsal stress fracture and a cohort of recruits completing training with no injury (n=150) (p<0.05). A multinomial logistic regression model was developed to predict the risk of injury for the two sites compared with the no-injury group. Multinomial logistic regression results were back transformed from log scale and presented in Relative Risk Ratios (RRR) with 95% confidence intervals (CI). RESULTS Lower dynamic arch index (high arch) (RRR: 0.75, CI: 0.63-0.89, p<0.01) and lower foot abduction (RRR: 0.87, CI: 0.80-0.96, p<0.01) were identified as increasing risk for second metatarsal stress fracture, while younger age (RRR: 0.78, CI: 0.61-0.99, p<0.05) and later peak pressure at the second metatarsal head area (RRR: 1.19, CI: 1.04-1.35, p<0.01) were identified as risk factors for third metatarsal stress fracture. CONCLUSIONS For second metatarsal stress fracture, aspects of foot type have been identified as influencing injury risk. For third metatarsal stress fracture, a delayed forefoot loading increases injury risk. Identification of these different injury mechanisms can inform development of interventions for treatment and prevention.

Effectiveness of Non-Pharmacological Interventions to Reduce Procedural Anxiety in Children and Adolescents Undergoing Treatment for Cancer: A Systematic Review and Meta-Analysis

Objective: Children and young people (CYP) with cancer undergo painful and distressing procedures. We aimed to systematically review the effectiveness of non-pharmacological interventions to reduce procedural anxiety in CYP. Methods: Extensive literature searches sought randomised controlled trials that quantified the effect of any non-pharmacological intervention for procedural anxiety in CYP with cancer aged 0-25. Study selection involved independent title and abstract screening and full text screening by two reviewers. Anxiety, distress, fear and pain outcomes were extracted from included studies. Where similar intervention, comparator and outcomes presented, metaanalysis was performed, producing pooled effect sizes (Cohen’s d) and 95% confidence intervals (95% CI). All other data were narratively described. Quality and risk of bias appraisal was performed, based on the Cochrane Risk of Bias tool. Results: Screening of 11,727 records yielded 56 relevant full texts. There were 15 included studies, eight trialling hypnosis, and seven non-hypnosis interventions. There were large, statistically significant reductions in anxiety and pain for hypnosis, particularly compared to treatment as usual (anxiety: d=2.30; 95% CI: 1.30 to 3.30, p<0.001; pain: d=2.16; 95% CI: 1.41 to 2.92, p<0.001). Evidence from non-hypnosis interventions was equivocal, with some promising individual studies. There was high risk of bias across included studies limiting confidence in some positive effects. Conclusions: Evidence suggests promise for hypnosis interventions to reduce procedural anxiety in CYP undergoing cancer treatment. These results largely emerge from one research group, therefore wider research is required. Promising evidence for individual non-hypnosis interventions must be evaluated through rigorously conducted randomised controlled trials.