The assessment of loading during walking and running has historically been limited to data collection in laboratory settings or with devices that require a computer connection. This study aims to ...determine if the loadsol
-a single sensor wireless insole-is a valid and reliable method of assessing force. Thirty (17 male and 13 female) recreationally active individuals were recruited for a two visit study where they walked (1.3 m/s) and ran (3.0 and 3.5 m/s) at a 0%, 10% incline, and 10% decline, with the visits approximately one week apart. Ground reaction force data was collected on an instrumented treadmill (1440 Hz) and with the loadsol
(100 Hz). Ten individuals completed the day 1 protocol with a newer 200 Hz loadsol
. Intraclass correlation coefficients (ICC3,k) were used to assess validity and reliability and Bland⁻Altman plots were generated to better understand loadsol
validity. Across conditions, the peak force ICCs ranged from 0.78 to 0.97, which increased to 0.84⁻0.99 with the 200 Hz insoles. Similarly, the loading rate ICCs improved from 0.61 to 0.97 to 0.80⁻0.96 and impulse improved from 0.61 to 0.97 to 0.90⁻0.97. The 200 Hz insoles may be needed for loading rate and impulse in running. For both walking and running, the loadsol
has excellent between-day reliability (>0.76).
Harrison, K, Williams, DSB III, Darter, BJ, Zernicke, RF, Shall, M, and Finucane, S. Effect of strength and plyometric training on kinematics in female novice runners. J Strength Cond Res 38(6): ...1048-1055, 2024-Both running performance and injury have been associated with running kinematics. Plyometric training improves run performance and reduces injury risk in court-sport and field-sport athletes. The aim of this study was to assess longitudinal changes in kinematics in novice runners before and after a typical beginners' running program, compared with those who perform a plyometric intervention before running. Fifty-seven novice female runners were assigned to the control group (8 weeks walking +8 weeks running) or the intervention group (8 weeks strength or plyometric training +8 weeks running). Kinematics were assessed at baseline, 8 weeks, and 16 weeks. Joint angles throughout the stride of those who completed the training ( n = 21) were compared between groups and assessment time points using a statistical parametric mapping 2-way analysis of variance, with group and study time point as independent variables. There was no interaction effect of group and study time point ( p > 0.05), indicating that both training programs had similar effects on running kinematics. There was a main effect of time for sagittal plane knee and hip kinematics ( p < 0.001); after training, subjects ran with a more extended leg, particularly during swing. Programs of 8 weeks of preparatory training, followed by 8 weeks of running, resulted in altered sagittal plane biomechanics, which have previously been related to improved running economy. A greater volume of plyometric, run training or concurrent plyometric and run training may be required to elicit changes in running form associated with lower injury risk.
PURPOSECoordination and coordination variability have been used as a measure of the function and flexibility of the sensorimotor system during running. Chronic ankle instability (CAI) is associated ...with altered sensorimotor system function compared with individuals without CAI. Copers may have adopted protective sensorimotor adaptations to prevent repeated ankle sprains; however, their coordination strategies between the foot and shank have not been investigated. We compared joint coupling angles and coordination variability using vector coding between individuals with CAI, copers, and controls.
METHODSSeventeen individuals with CAI, 17 copers, and 17 controls ran on the treadmill at a fixed speed of 2.68 m·s. A 10-s trial of continuous data was collected for kinematic analysis. The first five complete strides were used for vector coding. Means of the vector coding angles and variability of frontal plane ankle motion/transverse plane tibia motion and sagittal plane ankle motion/transverse plane tibia motion (SAK/TT) were calculated. A curve analysis with 90% confidence intervals was performed to detect differences between groups.
RESULTSControls demonstrated greater angles of SAK/TT than individuals with CAI and greater angles of FAK/TT than copers during the second half of stance. In general, the control group demonstrated greater variability than individuals with CAI and copers, and copers demonstrated greater variability than individuals with CAI.
CONCLUSIONSChronic ankle instability and copers demonstrated different coordination strategies than controls during loading and propulsion, adding evidence to support a sensorimotor deficit or compensation. Further, limited variability in people with history of CAI during impact and midstance may contribute to higher risk of reinjury, and be an important area for further research.
PURPOSEHigh school cross-country runners have a high incidence of injury, particularly at the shin and knee. An increased step rate during running has been shown to reduce impact forces and loading ...of the lower extremity joints. The purpose of this prospective study was to examine step rate as a risk factor for injury occurrence.
MATERIALS AND METHODSRunning step rates of 68 healthy high school cross-country runners (47 females; 21 males; mean age 16.2 ± 1.3 yr) were assessed at a fixed speed (3.3 ± 0.0 m·s) and self-selected speed (mean, 3.8 ± 0.5 m·s). Runners were prospectively followed during the interscholastic season to determine athletic exposures, occurrences of shin injury and anterior knee pain (AKP), and days lost to injury.
RESULTSDuring the season, 19.1% of runners experienced a shin injury and 4.4% experienced AKP. Most injuries (63.6%) were classified as minor (1–7 d lost). At the fixed speed, runners in the lowest tertile of step rate (≤164 steps per minute) were more likely (odds ratio, 6.67; 95% confidence interval, 1.2–36.7; P = 0.03) to experience a shin injury compared with runners in the highest tertile (≥174 steps per minute). Similarly, for self-selected speed, runners in the lowest tertile (≤166 steps per minute) (odds ratio, 5.85; 95% confidence interval, 1.1–32.1; P < 0.04) were more likely to experience a shin injury than runners in the highest tertile (≥178 steps per minute). AKP incidence was not significantly influenced by step rate.
CONCLUSIONA lower running step rate was associated with a greater likelihood of shin injury at both self-selected and fixed running speeds. Future studies evaluating whether increasing running step rate reduces shin injury risk and time lost during a high school cross-country season should be considered.
OBJECTIVES:Optimal fixation technique after purely ligamentous Lisfranc injury remains controversial. This biomechanical study compares dorsal plate versus transarticular screw fixation by measuring ...dorsal and plantar joint diastasis. A unique protocol was developed, using reflective triad markers and positional cameras.
METHODS:Eleven cadaveric matched pairs were assigned to either transarticular screw or dorsal plate fixation. Two reflective triad markers were placed into the medial cuneiform (C1) and second metatarsal base (MT2). Three cameras recorded the 3-dimensional location of triads to quantify C1-MT2 diastasis in the following statesintact Lisfranc ligament (INTACT), cut ligament (CUT), fixed (SCREW or PLATE) joint, and fixed joint after 10,000 loaded cycles. On completion, the plantar Lisfranc ligament insertions were identified, and plantar diastasis was determined using additional reflective triads. Statistical post hoc pairwise comparisons assessed differences in diastasis.
RESULTS:C1-MT2 diastasis in the CUT state increased relative to INTACT (P < 0.001). SCREW fixation reduced C1-MT2 diastasis relative to CUT at dorsal (P < 0.007) and plantar (P = 0.015) locations after cycling. PLATE fixation significantly reduced dorsal diastasis relative to CUT (P < 0.001) but not for plantar diastasis (P > 0.99). PLATE plantar diastasis was numerically higher than INTACT but not significantly (P > 0.39). PLATE plantar diastasis tended to be greater than SCREW before cycling (P = 0.068) and after cycling (P = 0.080).
CONCLUSIONS:Transection of the Lisfranc ligament complex yielded C1-MT2 diastasis. Both SCREW and PLATE fixation successfully reduced dorsal diastasis. However, upon load, the PLATE resulted in greater plantar diastasis, nearly statistically different relative to the SCREW. Cyclic loading at 343 N did not worsen diastasis.
Introduction L'élastine, principale constituant de la matrice extracellulaire des tissus élastiques (peau, vaisseaux, poumons) présente la particularité d'avoir une expression quasi nulle dans ces ...tissus après l'adolescence et n'est donc pas renouvelée. Au cours du vieillissement, l'élastine est dégradée par les élastases (cathepsine S, MMP-2, – 9, – 12…) en peptides bioactifs, appelés élastokines ou elastin derived peptides (EDP). Ces EDP sont entre autre des facteurs prédisposant aux maladies cardiovasculaires (Gayral et al. 2014) et à l'insulino-résistance (Blaise et al. 2013). De façon surprenante, l'élastine a été retrouvée dans le tissu hépatique de patients avec une cirrhose non alcoolique et notre laboratoire a mis en évidence chez la souris que cette expression est rapidement dégradée par les élastases en EDP (résultats non publiés). L'objectif de cette étude est de déterminer le role de l'ensemble de ces EDP sur la fonction métabolique. Matériels et Méthodes Dans le but de reproduire un vieillissement vasculaire physio/pathologique, en accord avec le comité local d'éthique, des souris avec un régime HFD ou non sont injectées avec EDP (une fois par semaine pendant huit semaines, pour mimer l'accumulation de PDE au cours du vieillissement physiologique). Nous avons focalisé la suite de notre étude sur l'homéostasie du glucose et le métabolisme hépatique. Résultats Les injections de EDP associées ou non à un HFD, engendrent une augmentation du poids des souris, une hypertrophie adipocytaire, une insulinorésistance et une stéatose hépatique. Cependant l'évolution de cette dernière semble être dépendante du régime. En effet, nous avons pu mettre en évidence l'apparition d'une fibrose associée à une accumulation de graisses hépatiques chez des souris traitées avec les EDP et nourries un régime normal. Chez les souris nourries par un régime gras les EDP n'induisent pas de synthèse de collagène alors qu'il existe une potentialisation dans l'accumulation des triglycérides hépatique et l'insulino-résistance. Conclusions L'accumulation chronique EDP engendre une stéatose hépatique non alcoolique associée à une obésité et à une insulino-résistance. Notre modèle pourrait être un modèle complémentaire au modèle CCl4 pour l'étude de la NASH.
ABSTRACTPowell, DW and Williams, DSB. Changes in vertical and joint stiffness in runners with advancing age. J Strength Cond Res 32(12)3425–3431, 2018—Age-related changes in the neuromuscular system ...underlie reduced performance and injury but may be mitigated through regular physical activity. It was hypothesized that older (OLD) compared with young (YOUNG) adults would exhibit greater vertical and joint stiffness when running at 3.35 m·s. Nine YOUNG and 10 OLD runners performed over ground running trials while three-dimensional biomechanics were recorded. Ankle and knee joint angles, moments and stiffness values were compared between YOUNG & OLD. YOUNG had smaller vertical stiffness (p = 0.01; YOUNG32.8 ± 3.6; OLD38.1 ± 5.7) and greater joint stiffness than OLD at the ankle (p = 0.04; YOUNG0.134 ± 0.021; OLD0.118 ± 0.017) and knee (p = 0.01; YOUNG0.119 ± 0.016; OLD0.098 ± 0.014). YOUNG exhibited greater peak knee flexion angles (p = 0.04; YOUNG43.4 ± 6.5°; OLD39.1 ± 2.6°), and peak ankle plantarflexion (p = 0.02; YOUNG−2.8 ± 0.4 Nm·kg; OLD−2.5 ± 0.1 Nm·kg) and knee extension moments (p < 0.01; 2.6 ± 0.3 Nm·kg; OLD2.1 ± 0.2 Nm·kg) than OLD whereas no differences were observed in peak ankle dorsiflexion angles (p = 0.44; YOUNG23.6 ± 4.2°; OLD23.4 ± 2.1°). The findings of this study suggest that OLD compared with YOUNG adults adopt altered lower extremity biomechanics. These altered running biomechanics by seek to minimize the metabolic cost of running or may be a function of reduced lower extremity strength and power.
Running speed is slower in middle-aged compared to younger runners due to reduced ankle but not hip and knee kinetic output. Running-specific training helps attenuate age-related declines in measures ...of endurance, muscle strength and gait speed. Considering the adaptability of the human body in response to imposed stresses, maintaining training volume and intensity may play a role in modifying running biomechanics in middle-aged runners.
PURPOSETo compare running biomechanics between young and middle-aged runners when controlling for the confounding effects of training volume and intensity.
METHODS15 middle-aged runners, 15 young runners with similar training volume as the middle-aged group and, 15 young runners with similar preferred training paces (i.e. intensity) as the middle-aged runners participated in the study. Lower limb joint kinetics were calculated from kinematic and ground reaction force data during over-ground running at a submaximal speed and compared among groups.
RESULTSMiddle-aged runners ran with similar peak ankle power compared to volume-matched younger runners although peak plantarflexor moment was 10.5% lower in the middle aged group (p = 0.046; Cohen’s d = 0.78). Middle-aged runners ran with similar ankle plantarflexor moment and joint power compared to training pace-matched young runners. As expected, no age-related differences were observed in hip and knee kinetics when training volume or pace were matched between age groups. These results suggest that training pace may be more effective in attenuating age-related declines in plantarflexor kinetics in middle-aged runners.
CONCLUSIONFrom these findings, we propose the hypothesis that both training volume and training pace may play a role in maintaining plantarflexor kinetics but that training pace may have a greater impact on ankle plantarflexor kinetics in middle-aged runners.
The primary objective of this study was to evaluate 1-week reproducibility of post-occlusive reactive hyperemia (PORH) and local thermal hyperemia (LTH) assessed by single-point laser-Doppler ...flowmetry (LDF) on different skin sites. We also evaluated spatial reproducibility of both tests on the forearm. Finally, we assessed the influence of mental stress and room temperature variations on PORH and LTH.
We performed PORH and LTH assessing skin blood flow on the forearm and on the finger pad with LDF. We repeated the sequence 1 week later. We also performed PORH and LTH during mental stress (Stroop test) and at room temperatures of 21 °C and 27 °C. Data were expressed as cutaneous vascular conductance (CVC), as a function of baseline and as a function of 44 °C vasodilation (%CVC
44). Reproducibility was expressed as within subject coefficients of variation (CV) and intra-class correlation coefficients (ICC).
Fourteen Caucasian healthy volunteers were recruited. Median age was 25 (2.7) and 50% were female. Median body mass index was 21.2 (5). PORH was reproducible on the finger, whether expressed as raw CVC (CV
=
25%; ICC
=
0.56) or as %CVC
44 (CV
=
24%; ICC
=
0.60). However, PORH showed poor reproducibility on the forearm. In the same way, LTH was reproducible on the finger pad when expressed as CVC (CV
=
17%; ICC
=
0.81) but not on the forearm. Spatial reproducibility was poor on the forearm. Elevated room temperature (27 °C) affected PORH and LTH on the finger pad (
p
<
0.05) but not on the forearm.
Single-point LDF is a reproducible technique to assess PORH and LTH on the finger pad when data are expressed as raw CVC or %CVC
44. On the forearm, however, it shows great inter-day variability, probably due to spatial variability of capillary density. These results highlight the need for alternative techniques on the forearm.
Lower extremity stiffness describes the relative loading and kinematics of the entire lower extremity during ground contact. Previously injured subjects demonstrate altered lower extremity stiffness ...values. Clinical analysis of lower extremity stiffness is not currently feasible due to increased time and cost.
To determine the clinically identifiable contributors to lower extremity stiffness.
In this cross-sectional controlled laboratory study, 92 healthy runners completed a clinical screening involving passive assessment of hip, knee, and ankle range of motion, along with body anthropometrics. The range of motion was predominantly assessed in the sagittal and frontal planes. In the same session, runners completed an overground kinematic and kinetic running assessment at 3.35 m/s (±5%) to obtain lower extremity stiffness. Correlations between lower extremity stiffness and clinical variables were completed. Modifiable variables were included in an all-possible-linear regressions approach to determine a parsimonious model for predicting lower extremity stiffness.
Clinically modifiable measures included in the regression model accounted for 48.4% of the variance of lower extremity stiffness during running. The variables that predicted greater stiffness included greater body mass, less ankle dorsiflexion range of motion with the knee flexed, less hip internal rotation range of motion, and less first-ray mobility.
Reduced lower extremity range of motion and greater body mass are associated with greater lower extremity stiffness during running. These variables could be addressed clinically to potentially alter lower extremity stiffness and injury risk. J Orthop Sports Phys Ther 2019;49(2):98-104. Epub 27 Jul 2018. doi:10.2519/jospt.2019.7683.
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