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Purpose: There are important methodological considerations for translating wearable-based gait-monitoring data to field settings. This study investigated different devices' sampling rates, signal lengths, and testing frequencies for athlete monitoring using dynamical systems variables. Methods: Secondary analysis of previous wearables data (N = 10 runners) from a 5-week intensive training intervention investigated impacts of sampling rate (100–2000 Hz) and signal length (100–300 strides) on detection of gait changes caused by intensive training. Primary analysis of data from 13 separate runners during 1 week of field-based testing determined day-to-day stability of outcomes using single-session data and mean data from 2 sessions. Stride-interval long-range correlation coefficient α from detrended fluctuation analysis was the gait outcome variable. Results: Stride-interval α reduced at 100- and 200- versus 300- to 2000-Hz sampling rates (mean difference: −.02 to −.08; P ≤.045) and at 100- compared to 200- to 300-stride signal lengths (mean difference: −.05 to −.07; P <.010). Effects of intensive training were detected at 100, 200, and 400 to 2000 Hz (P ≤.043) but not 300 Hz (P =.069). Within-athlete α variability was lower using 2-session mean versus single-session data (smallest detectable change:.13 and.22, respectively). Conclusions: Detecting altered gait following intensive training was possible using 200 to 300 strides and a 100-Hz sampling rate, although 100 and 200 Hz underestimated α compared to higher rates. Using 2-session mean data lowers smallest detectable change values by nearly half compared to single-session data. Coaches, runners, and researchers can use these findings to integrate wearable-device gait monitoring into practice using dynamic systems variables. [ABSTRACT FROM AUTHOR]

The ability to estimate lower-extremity mechanics in real-world scenarios may untether biomechanics research from a laboratory environment. This is particularly important for military populations where outdoor ruck marches over variable terrain and the addition of external load are cited as leading causes of musculoskeletal injury As such, this study aimed to examine (1) the validity of a minimal IMU sensor system for quantifying lower-extremity kinematics during treadmill walking and running compared with optical motion capture (OMC) and (2) the sensitivity of this IMU system to kinematic changes induced by load, grade, or a combination of the two. The IMU system was able to estimate hip and knee range of motion (ROM) with moderate accuracy during walking but not running. However, SPM analyses revealed IMU and OMC kinematic waveforms were significantly different at most gait phases. The IMU system was capable of detecting kinematic differences in knee kinematic waveforms that occur with added load but was not sensitive to changes in grade that influence lower-extremity kinematics when measured with OMC. While IMUs may be able to identify hip and knee ROM during gait, they are not suitable for replicating lab-level kinematic waveforms. [ABSTRACT FROM AUTHOR]

• Exercise relative motion orthoses are used during exercise and function to improve PIPJ motion. • The affected finger's MCPJ is typically positioned in 11-30° relative extension or flexion. • A 4-finger design is more commonly used for border digits than a 3-finger design. • Exercise RM orthoses are prescribed more for active/passive PIPJ extension rather than flexion deficits. • Exercise RM orthoses are prescribed more for active PIPJ extension/flexion deficits than passive deficits. Cross-sectional online survey. Exercise relative motion (RM) orthoses are prescribed by hand therapists to improve finger motion but there is limited scientific evidence to guide practice. To describe Australian hand therapists' use of exercise RM orthoses to improve PIPJ motion, including trends in orthosis design, prescription, clinical conditions, and their opinions on orthosis benefits and limitations. 870 Australian Hand Therapy Association members were sent an electronic survey that included multiple choice, Likert scale and open-ended questions under four subgroups: demographics, design trends, prescription, and therapist opinions. Data analysis consisted of predominantly descriptive statistics and verbatim transcription. 108 Australian therapists completed the survey, over a third with ≥ 20 years of clinical experience. Exercise RM orthoses were prescribed weekly to monthly (82%) for between 2-6 weeks duration (81%) and used during exercise and function (87%). The most common differential MCPJ position was 11-30° extension (98%) or flexion (92%). Four-finger designs were most common for border digits (OR ≥3.4). Exercise RM orthoses were more commonly used for active and extension deficits compared to passive (OR ≥3.7) and flexion deficits (OR ≥1.4), respectively. Clinicians agreed that the orthosis allowed functional hand use (94%), increased non-intentional exercise (98%), and was challenging to use with fluctuating oedema (60%). This survey highlights notable clinical trends despite only reaching a small sample of Australian hand therapists. Exercise RM orthoses were frequently being used for active PIPJ extension and flexion deficits. A common MCPJ differential angle was reported, while the number of fingers incorporated into the design depended on the digit involved. Therapists' preferences mostly agreed with the limited available evidence. This limited survey identified common exercise RM orthosis fabrication and prescription trends amongst Australian therapists. These insights may inform future biomechanical and clinical research on this underexplored topic. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the behaviour of physiological load measures as well as ground reaction forces (GRF) and acceleration load during a prolonged running task that simulated the running demands of an intermittent team sport. Nineteen males completed a maximal aerobic fitness test and an extended running protocol across two sessions. Participants wore a portable metabolic system, and four inertial measurement units (IMU), one on each foot, the lower back and upper back. GRF were measured via an instrumented treadmill. Change in metabolic, IMU and GRF variables across five blocks during the running protocol were assessed using a one-way repeated measures ANOVA. The running protocol elicited large increases in heart rate and oxygen consumption over time. No statistically significant changes in any peak impact accelerations were observed. Resultant acceleration area under the curve (AUC) increased at the lower and upper back locations but was unchanged at the foot. GRF active peak but not impact peak increased during the prolonged run. The results of this study indicate that the effect of an extended running task on IMU measures of external mechanical load is manifested in the upper body, and is effectively measured by AUC. [ABSTRACT FROM AUTHOR]

Wade, JA, Fuller, JT, Devlin, PJ, and Doyle, TLA. Senior and junior rugby league players improve lower-body strength and power differently during a rugby league season. J Strength Cond Res 36(5): 1367–1372, 2022—This investigation evaluated lower-body strength and power changes across a rugby league season in elite junior and senior athletes. Twenty-five senior and 20 junior rugby league players performed an isometric midthigh pull and countermovement jump at 3 time points in a National Rugby League training season (mid-preseason, end-preseason, and in-season). Linear fixed-effects models were used to compare isometric midthigh pull force and countermovement jump power between player experience groups (senior vs. junior) across the season phases (mid-preseason vs. end-preseason vs. and in-season). Cohen's effect sizes (ES) with 95% confidence intervals were calculated for pairwise comparisons. For senior players, absolute and relative strength (ES = 0.38, p < 0.007) and power (ES = 0.64, p < 0.008) increases were observed at end-preseason compared with mid-preseason, but there were no changes in-season (ES = 0.02, p > 0.571). For junior players, strength did not change (ES < 0.01, p > 0.738) and absolute power decreased (ES = 0.29, p < 0.014) at end-preseason compared with mid-preseason; large increases were evident for absolute and relative strength (ES = 1.43, p < 0.001) and power (ES = 0.62, p < 0.001) in-season. This research demonstrates senior and junior rugby league players exhibit unique patterns of improvements in lower-body strength and power across different phases of the season. This highlights the importance for training programs to differ between junior and senior athletes and target different physical qualities for both groups at different times of the season, thus providing guidance for strength and conditioning coaches. [ABSTRACT FROM AUTHOR]

* OBJECTIVE: To evaluate the effectiveness of running gait retraining on kinematics, kinetics, performance, pain, and injury in distance runners. t DESIGN: Intervention systematic review with meta-analysis. * LITERATURE SEARCH: Seven electronic databases from inception to March 2021. * TRIAL SELECTION CRITERIA: Randomized controlled trials that (1) evaluated running gait retraining compared to no intervention, usual training, placebo, or standard care and (2) reported biomechanical, physiological, performance, or clinical outcomes. * DATA SYNTHESIS: Random-effects metaanalyses were completed, and the certainty of evidence was judged using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. We categorized interventions into step rate, non-rearfoot footstrike, impact, ground contact time, and multiparameter subgroups. * RESULTS: We included 19 trials (673 participants). Moderate-certainty evidence indicated step rate gait retraining increased step rate (SMD 1.03 [95% confidence interval {CI}: 0.63, 1.44]; number of trials (N): 4; I²: 0%) and reduced average vertical loading rate (SMD -0.57 [95% CI, -1.05 to -0.09], N: 3; I²: 0%). Low-certainty evidence indicated non-rearfoot footstrike retraining increased knee flexion at initial contact (SMD 0.74 [95% CI, 0.11 to 1.37]; N: 2; I²: 0%), but did not alter running economy (SMD 0.21 [95% CI, -1.11 to 1.52]; N: 3; I²: 19%).). Low-certainty evidence indicated multiparameter retraining did not alter running economy (SMD 0.32 [-0.39, 1.02]; N: 3; I²: 19%) or performance (SMD 0.14 [95% CI, -4.87 to 4.58]; N: 2; I²: 18%). Insufficient trials reported on pain outcomes. Two trials demonstrated reduced 1-year injury incidence following gait retraining. * CONCLUSIONS: Gait retraining interventions altered step rate and knee kinematics, lowered vertical loading rates, and did not affect running performance. [ABSTRACT FROM AUTHOR]

Background: Treadmills are often used in research, clinical practice, and training. Biomechanical investigations comparing treadmill and overground running report inconsistent findings. Objective: This study aimed at comparing biomechanical outcomes between motorized treadmill and overground running. Methods: Four databases were searched until June 2019. Crossover design studies comparing lower limb biomechanics during non-inclined, non-cushioned, quasi-constant-velocity motorized treadmill running with overground running in healthy humans (18–65 years) and written in English were included. Meta-analyses and meta-regressions were performed where possible. Results: 33 studies (n = 494 participants) were included. Most outcomes did not differ between running conditions. However, during treadmill running, sagittal foot–ground angle at footstrike (mean difference (MD) − 9.8° [95% confidence interval: − 13.1 to − 6.6]; low GRADE evidence), knee flexion range of motion from footstrike to peak during stance (MD 6.3° [4.5 to 8.2]; low), vertical displacement center of mass/pelvis (MD − 1.5 cm [− 2.7 to − 0.8]; low), and peak propulsive force (MD − 0.04 body weights [− 0.06 to − 0.02]; very low) were lower, while contact time (MD 5.0 ms [0.5 to 9.5]; low), knee flexion at footstrike (MD − 2.3° [− 3.6 to − 1.1]; low), and ankle sagittal plane internal joint moment (MD − 0.4 Nm/kg [− 0.7 to − 0.2]; low) were longer/higher, when pooled across overground surfaces. Conflicting findings were reported for amplitude of muscle activity. Conclusions: Spatiotemporal, kinematic, kinetic, muscle activity, and muscle–tendon outcome measures are largely comparable between motorized treadmill and overground running. Considerations should, however, particularly be given to sagittal plane kinematic differences at footstrike when extrapolating treadmill running biomechanics to overground running. Protocol registration CRD42018083906 (PROSPERO International Prospective Register of Systematic Reviews). [ABSTRACT FROM AUTHOR]

Accelerometers are often placed on the tibia to measure segmental accelerations, and external mechanical load during running. However, in applied sport settings it is sometimes preferable to place accelerometers on the dorsal foot to avoid tibial impact injuries. This study aimed to quantify the differences in accelerations measured at the dorsal foot compared with the distal tibia during running. Sixteen recreationally active participants performed a sprint protocol on a non-motorised treadmill. Accelerometers were positioned bilaterally on the medial tibia (TIBLeft and TIBRight), and bilateral dorsal foot surfaces (DORLeft and DORRight). Continuous acceleration signal waveform analysis was performed using one-dimensional statistical parametric mapping (1DSPM). Resultant accelerations were greater for DORLeft than TIBLeft for 60% of the gait cycle (p < 0.001) and greater for DORRight than TIBRight for 50% of the gait cycle (p < 0.003). The larger accelerations at the dorsal foot than the tibia can be explained by movement at the ankle joint, and the placement location relative to the hip. The dorsal foot location can be used to effectively measure accelerations and external mechanical load when it is not feasible to place the accelerometer on the tibia, however results between the two locations should not be compared. [ABSTRACT FROM AUTHOR]

This study investigated whether male runners improve running performance, running economy, ankle plantar flexor strength, and alter running biomechanics and lower limb bone mineral density when gradually transitioning to using minimalist shoes for 100% of weekly running. The study was a planned follow-up of runners (n = 50) who transitioned to minimalist or conventional shoes for 35% of weekly structured training in a previous 6-week randomised controlled trial. In that trial, running performance and economy improved more with minimalist shoes than conventional shoes. Runners in each group were instructed to continue running in their allocated shoe during their own preferred training programme for a further 20 weeks while increasing allocated shoe use to 100% of weekly training. At the 20-week follow-up, minimalist shoes did not affect performance (effect size: 0.19; p = 0.218), running economy (effect size: ≤ 0.24; p ≥ 0.388), stride rate or length (effect size: ≤ 0.12; p ≥ 0.550), foot strike (effect size: ≤ 0.25; p ≥ 0.366), or bone mineral density (effect size: ≤ 0.40; p ≥ 0.319). Minimalist shoes increased plantar flexor strength more than conventional shoes when runners trained with greater mean weekly training distances (shoe*distance interaction: p = 0.036). After greater improvements with minimalist shoes during the initial six weeks of a structured training programme, increasing minimalist shoe use from 35% to 100% over 20 weeks, when runners use their own preferred training programme, did not further improve performance, running economy or alter running biomechanics and lower limb bone mineral density. Minimalist shoes improved plantar flexor strength more than conventional shoes in runners with greater weekly training distances. [ABSTRACT FROM AUTHOR]

This study investigated whether male runners improve running performance, running economy, ankle plantar flexor strength, and alter running biomechanics and lower limb bone mineral density when gradually transitioning to using minimalist shoes for 100% of weekly running. The study was a planned follow-up of runners (n = 50) who transitioned to minimalist or conventional shoes for 35% of weekly structured training in a previous 6-week randomised controlled trial. In that trial, running performance and economy improved more with minimalist shoes than conventional shoes. Runners in each group were instructed to continue running in their allocated shoe during their own preferred training programme for a further 20 weeks while increasing allocated shoe use to 100% of weekly training. At the 20-week follow-up, minimalist shoes did not affect performance (effect size: 0.19; p = 0.218), running economy (effect size: ≤ 0.24; p ≥ 0.388), stride rate or length (effect size: ≤ 0.12; p ≥ 0.550), foot strike (effect size: ≤ 0.25; p ≥ 0.366), or bone mineral density (effect size: ≤ 0.40; p ≥ 0.319). Minimalist shoes increased plantar flexor strength more than conventional shoes when runners trained with greater mean weekly training distances (shoe*distance interaction: p = 0.036). After greater improvements with minimalist shoes during the initial six weeks of a structured training programme, increasing minimalist shoe use from 35% to 100% over 20 weeks, when runners use their own preferred training programme, did not further improve performance, running economy or alter running biomechanics and lower limb bone mineral density. Minimalist shoes improved plantar flexor strength more than conventional shoes in runners with greater weekly training distances. [ABSTRACT FROM AUTHOR]

Context: Minimalist shoes have been suggested as a way to alter running biomechanics to improve running performance and reduce injuries. However, to date, researchers have only considered the effect of minimalist shoes at slow running speeds. Objective: To determine if runners change foot-strike pattern and alter the distribution of mechanical work at the knee and ankle joints when running at a fast speed in minimalist shoes compared with conventional running shoes. Design: Crossover study. Setting: Research laboratory. Patients or Other Participants: Twenty-six trained runners (age=30.0 6 7.9 years [age range, 18-40 years], height=1.79 6 0.06 m, mass = 75.3 6 8.2 kg, weekly training distance = 27 6 15 km) who ran with a habitual rearfoot foot-strike pattern and had no experience running in minimalist shoes. Intervention(s): Participants completed overground running trials at 18 km/h in minimalist and conventional shoes. Main Outcome Measure(s): Sagittal-plane kinematics and joint work at the knee and ankle joints were computed using 3-dimensional kinematic and ground reaction force data. Footstrike pattern was classified as rearfoot, midfoot, or forefoot strike based on strike index and ankle angle at initial contact. Results: We observed no difference in foot-strike classification between shoes (v2 1=2.29, P=.13). Ankle angle at initial contact was less (2.468 versus 7.438; t25 = 3.34, P = .003) and strike index was greater (35.97% versus 29.04%; t25=2.38, P= .03) when running in minimalist shoes compared with conventional shoes. We observed greater negative (52.87 J versus 42.46 J; t24 = 2.29, P = .03) and positive work (68.91 J versus 59.08 J; t24=2.65, P=.01) at the ankle but less negative (59.01 J versus 67.02 J; t24= 2.25, P= .03) and positive work (40.37 J versus 47.09 J; t24 = 2.11, P = .046) at the knee with minimalist shoes compared with conventional shoes. Conclusions: Running in minimalist shoes at a fast speed caused a redistribution of work from the knee to the ankle joint. This finding suggests that runners changing from conventional to minimalist shoes for short-distance races could be at an increased risk of ankle and calf injuries but a reduced risk of knee injuries. [ABSTRACT FROM AUTHOR]

This study investigated the relationships between inertial measurement unit (IMU) acceleration at multiple body locations and 3D motion capture impact landing measures in runners. Thirty healthy runners ran on an instrumented treadmill at five running speeds (9–17 km/h) during 3D motion capture. Axial and resultant acceleration were collected from IMUs at the distal and proximal tibia, distal femur and sacrum. Relationships between peak acceleration from each IMU location and patellofemoral joint (PFJ) peak force and loading rate, impact peak and instantaneous vertical loading rate (IVLR) were investigated using linear mixed models. Acceleration was positively related to IVLR at all lower limb locations (p < 0.01). Models predicted a 1.9–3.2 g peak acceleration change at the tibia and distal femur, corresponding with a 10% IVLR change. Impact peak was positively related to acceleration at the distal femur only (p < 0.01). PFJ peak force was positively related to acceleration at the distal (p = 0.03) and proximal tibia (p = 0.03). PFJ loading rate was positively related to the tibia and femur acceleration in males only (p < 0.01). These findings suggest multiple IMU lower limb locations are viable for measuring peak acceleration during running as a meaningful indicator of IVLR. [ABSTRACT FROM AUTHOR]

Purpose: To examine the effects of increased cadence and minimalist footwear on lower-limb variability in runners with patellofemoral pain (PFP). Methods: Fifteen (12 female, 3 male) runners with PFP ran on an instrumented treadmill with three-dimensional motion capture in three randomly ordered conditions: (i) standard shoe at preferred cadence, (ii) standard shoe +10% cadence, and (iii) minimalist shoe at preferred cadence. Vector coding was used to calculate coordination variability between strides for select lower-limb joint couplings. Approximate entropy was calculated to assess continuous variability for segment kinematic and kinetic data and compared between conditions using repeated-measures ANOVA. One-dimensional statistical parametric mapping repeated-measures ANOVA was performed on the coordination variability data. Cohen's d effect size was calculated for all comparisons. Results: Larger approximate entropy values (i.e., greater variability) were observed for the standard shoe +10% cadence versus the standard shoe at preferred cadence for hip flexion/extension (P < 0.001; d = 1.12), hip adduction/abduction (P < 0.001; d = 0.99) and ankle dorsiflexion/plantarflexion (P < 0.001; d = 1.37) kinematics, and knee flexion/extension moments (P < 0.001; d = 0.93). Greater variability was also observed in the minimalist shoe versus the standard shoe at preferred cadence for hip internal/external rotation moments (P < 0.001; d = 0.76), knee adduction/abduction moments (P < 0.001; d = 0.51), and knee internal/external rotation moments (P < 0.001; d = 1.02). One-dimensional statistical parametric mapping repeated-measures ANOVA revealed no significant differences in coordination variability between running conditions. Conclusions: Greater hip and knee kinematic and kinetic variability observed with either increased cadence or minimalist footwear may be beneficial for those with PFP. [ABSTRACT FROM AUTHOR]

Gait retraining is advocated for the management of patellofemoral pain. This case series examined changes in lower limb variability following 6-weeks of gait retraining in individuals with patellofemoral pain. Six runners with patellofemoral pain completed a 6-week physiotherapist-guided gait retraining program using minimalist footwear and increased cadence. Approximate entropy joint variability and segment coordination variability were calculated across the entire gait cycle during running at baseline, 6 and 12 weeks and compared using repeated measures analysis of variance and the standardised mean difference (SMD). Compared to baseline, there were large increases in hip joint transverse plane kinematic variability at 6 (SMD = 1.7) and 12 weeks (SMD = 1.3). Moderate increases in hip joint frontal plane and knee joint sagittal plane kinematic variability were also observed at 6 (SMD = 1.1 & 0.96) and 12 weeks (SMD = 1.1 & 0.89). Knee joint frontal plane and hip joint transverse plane kinetic variability demonstrated large increases from baseline at 6 (SMD = 1.3 & 0.9) and 12 weeks (SMD = 0.9 & 1.0). There was no main effect of time for segment coordination variability. All participants had clinically meaningful improvements in pain (visual analogue change score > 20 mm). Gait retraining increased joint kinematic and kinetic variability in those with patellofemoral pain and these changes persisted over 12 weeks. Increased variability was observed in joint kinematics and kinetics known to influence patellofemoral joint stress, which may vary patellofemoral joint loading patterns and partly explain the clinical effect. • Gait retraining improves pain and increases joint variability. • Changes in joint variability persist post the gait retraining program. • Increased joint variability may vary tissue loading patterns and aid recovery. [ABSTRACT FROM AUTHOR]