François Delvaux

Purpose : The objective of this study was to compare the long-term effects of running retraining and minimalist footwear on running economy (RE), foot and ankle adaptations, and running biomechanics over a 12-month period. Method : In this randomized controlled trial, 61 habitual rearfoot runners were allocated to 3 groups: minimalist footwear (n = 19), running-retraining (n = 18), and control (n = 24). Participants were evaluated at baseline, 2, 6, and 12 months. Outcome measures included RE and biomechanics assessed on a treadmill at self-selected comfortable speed, as well as foot and ankle characteristics. Results : RE improved over time in all groups, with no clear between-group differences at any time point. RE significantly improved from baseline in both the minimalist group (+4.9% at 6 mo and +9.3% at 12 mo; P = .03 and P < .001, respectively) and the running-retraining group (+5.6% at 6 mo and +10.5% at 12 mo; P < .001 for both). The control group showed an improvement in RE (+4.7%) at 12 months compared to baseline ( P = .01). No significant changes were observed in foot and ankle characteristics in any group across the follow-up period. Conclusion : RE improved similarly across all groups, suggesting that neither running retraining nor transitioning to minimalist footwear provides additional benefits beyond the control condition over a 12-month period. Although descriptive trends indicated greater improvements in the intervention groups, substantial interindividual variability highlights the need to identify responders to these interventions in future studies.

The purposes of the study were to identify the key components of injury prevention exercise programmes (IPEPs) used by football coaches during training sessions, to explore the association between personal characteristics and IPEPs component use, and to examine coaches’ self-perceived competence in injury prevention. Football coaches from the French-speaking region of Belgium were invited to participate in a cross-sectional online survey. They were asked to report the components of the IPEPs they used in their training routines. Additionally, they were invited to self-assess their perceived level of expertise in injury prevention and to suggest potential avenues for improving this expertise. A total of 356 coaches fully completed the questionnaire. Among the injury prevention exercises used at least once a week, aerobic warm-ups were the most commonly used (96%), followed by stretching (74%), balance/agility exercises (66%), running/plyometrics (65%), core stability exercises (51%), and lower limb muscle strengthening (46%). Chi-squared tests indicated that higher levels of coach education and higher competitive levels of the teams coached were associated with a greater use of preventive exercises . More specifically, only 21% of respondents reported using the FIFA 11 + programme. A large majority (77%) of coaches reported feeling insufficiently qualified in the area of injury prevention. In conclusion, the core components of IPEPs used in Belgian football clubs were identified and their use appears to be primarily associated with the coaches’ level of education. Coaches indicated that they perceived themselves as insufficiently qualified with regard to injury prevention.

Context : A previous study has shown that strengthening the foot muscles could decrease the risk of running-related injuries by 2.4 times in endurance runners. However, it remains unclear whether runners with stronger foot muscle have less risk of running-related injuries. The aim of this study was to compare foot–ankle characteristics between runners with and without a history of running-related injury. Design : Retrospective case–control study. Methods : This study enrolled 225 runners in this retrospective study. The participants filled out a questionnaire related to their history of running-related injury during the previous year. A foot morphology screening and a maximal voluntary isometric strength of ankle plantar flexor, hallux, and lesser toe flexor were performed. The footstrike pattern and cadence were determined using a high-speed camera during a self-paced run on a treadmill. Results : Runners with and without a history of overuse running-related injury had no significant differences in foot–ankle muscle strength. However, faster runners were more likely to report a history of overuse foot injury (odds ratio: 1.51, 95% CI, 1.14 to 2.00; P = .004). Runners with a history of tibia injury were less experienced (odds ratio: 0.83, 95% CI, 0.69 to 0.99; P = .038) and had lower cadence (odds ratio: 0.84, 95% CI, 0.88 to 0.99; P = .042). Conclusions : Runners with a history of overuse running-related injury, whether affecting any anatomical region, or specifically the foot do not exhibit reduced foot–ankle muscle strength. Runners with and without a history of running-related injury had no differences in foot–ankle muscle strength, suggesting that foot–ankle strength alone was not associated with previous injury status in this cohort.

Running-related injuries (RRIs) have been linked to high-frequency components of impact-related variables. The influence of running retraining interventions on low- (LoF) and high-frequency (HiF) components of impact-related variables remains unexplored. This study investigated the effects of different retraining strategies on LoF and HiF components of impact-related variables. Twenty-six habitual rearfoot runners completed four overground running conditions: no instructions (CON), forefoot strike (FOR), increased cadence by 10% (CAD), and a combination of both (CADFOR). Three-dimensional kinematics were recorded, while ground reaction forces were processed to separate LoF and HiF signals (10 Hz as cut-off value). Compared to CON, HiF impact peak was reduced in FOR (p d = 2.0), CAD (p = 0.006, d = 0.6), and CADFOR (p d = 2.3). HiF instantaneous vertical loading rate was significantly reduced only in FOR (p d = 0.6) and CADFOR (p d = 0.7). Notably, adopting a forefoot strike pattern reduced HiF components of impact-related variables nearly three times more than cadence increase alone. The combination of forefoot strike and increased cadence produced the largest reduction in HiF impact components, suggesting it may be the most effective retraining strategy for potentially lowering RRI risk.

The aim of this study was to compare the foot-ankle joint mechanics of running drills and running. Seventeen long-distance runners performed five popular running drills (A-skip, B-skip, Bounding, Heel flicks, Straight leg running) and a run at 3.88 m/s. Kinematics, kinetics and power values were calculated for the ankle, midtarsal (MT) and metatarsophalangeal (MP) joints. Electromyographic activity was recorded for the soleus, gastrocnemius medialis, lateralis and abductor hallucis muscle. The A-skip, the B-skip and the Heel flicks induced a smaller ankle (p < 0.001, ŋ² = 0.41), MT (p < 0.001, ŋ² = 0.43) and MP (p < 0.001, ŋ² = 0.47) dorsiflexion peak than running. No difference was found between the running drills and running for ankle, MT and MP moment. The Bounding induces a higher positive ankle power than running (diff: 5.5 ± 7.5 J/kg, p = 0.014, d = 1.05). The A-skip (diff: 2.8 ± 2.9 J/kg, p < 0.001, d = 1.5) and the B-skip (diff: 2.7 ± 2.1 J/kg, p < 0.001, d = 1.4) induce a smaller MT positive power than running. This study offers an analysis of the mechanical behaviour of the foot-ankle complex to help track and field coaches select their running drills in an evidence-based manner.

Background and Purpose: Ankle muscle strength is an important criterion to consider and assess for return to play (RTP) after lateral ankle sprain (LAS). This study therefore focuses on the reported ankle muscle strength consideration for RTP by physicians and physiotherapists, both clinicians involved in RTP decisions, and how they assess it in daily practice. The primary aim is to compare reported clinical practice on ankle muscle strength evaluation between physicians and physiotherapists. Our secondary aims are: to assess the prevalence of use of qualitative versus quantitative assessment and; to determine if there are any differences in how clinicians with or without a Sports Medicine or Physiotherapy Education approach this assessment.Methods: A survey on RTP criteria after LAS was completed by 109 physicians in a previous study. A number of 103 physiotherapists completed the same survey. A comparison between clinicians' answers was realized and additional questions on ankle muscle strength were analysed.Results: Physiotherapists consider ankle strength for RTP more than physicians (p < 0.001). A large majority of physicians (93%) and physiotherapists (92%) reported assessing ankle strength manually and less than 10% use a dynamometer. Physicians and physiotherapists with Sports Medicine or Physiotherapy Education selected more quantitative assessment than those without (p < 0.001).Discussion: Despite being recognized as an important criterion, ankle muscle strength is not always part of the RTP criteria after LAS in daily practice. The dynamometers are scarcely used by physicians and physiotherapists, whereas it could accurately quantify ankle strength deficits. Sports Medicine or Physiotherapy Education increases the use of quantitative ankle strength assessments by clinicians.

COVID-19 vaccination raised concerns about its potential effects on physical performance. To assess the impact of COVID-19 vaccination on the perceived change in physical performance, we conducted an online survey among elite athletes from Belgium, Canada, France and Luxembourg, with questions about socio-demographics, COVID-19 vaccination, perceived impact on physical performance and perceived pressure to get vaccinated. Full vaccination was defined as two doses of mRNA or vector vaccine or a heterologous vaccine scheme. Among 1106 eligible athletes contacted, 306 athletes answered the survey and were included in this study. Of these, 72% perceived no change in their physical performance, 4% an improvement and 24% a negative impact following full COVID-19 vaccination. For 82% of the included athletes, the duration of the negative vaccine reactions was ≤3 days. After adjustment for potential confounding variables, practicing an individual sport, a duration of vaccine reactions longer than 3 days, a high level of vaccine reaction and the perceived pressure to get vaccinated were independently associated with a perceived negative impact on physical performance of more than 3 days after the vaccination. The perceived pressure to get vaccinated appears to be a parameter associated with the negative perceived change in the physical performance and deserves further consideration.