Morphological and viscoelastic properties of the Achilles tendon in the forefoot, rearfoot strike runners, and non-runners in vivo

The purpose of this study was to investigate the differences in the morphological and viscoelastic properties of the Achilles tendon (AT) among different groups (rearfoot strikers vs. forefoot strikers vs. non-runners). Thirty healthy men were recruited, including habitual forefoot strike runners (n = 10), rearfoot strike runners (n = 10), and individuals with no running habits (n = 10). The AT morphological properties (cross-sectional area and length) were captured by using an ultrasound device. The real-time ultrasound video of displacement changes at the medial head of the gastrocnemius and the AT junction during maximal voluntary isometric contraction and the plantar flexion moment of the ankle was obtained simultaneously by connecting the ultrasound device and isokinetic dynamometer via an external synchronisation box. The results indicated that male runners who habitually forefoot strike exhibited significantly lower AT hysteresis than male non-runners (p < 0.05). Furthermore, a greater peak AT force during maximal voluntary contraction was observed in forefoot strike male runners compared to that in male individuals with no running habits (p < 0.05). However, foot strike patterns were not related to AT properties in recreational male runners (p > 0.05). The lower AT hysteresis in male FFS runners implied that long-term forefoot strike patterns could enhance male-specific AT’s ability to store and release elastic energy efficiently during running, resulting in a more effective stretch-shortening cycle. The greater peak AT force in male FFS runners indicated a stronger Achilles tendon

EFFECTS OF 12-WEEK GAIT RETRAINING ON THE MORPHOLOGY OF MEDIAL GASTROCNEMIUS

The purpose of this study was to investigate the effects of 12-week gait retraining on the morphological properties of medial gastrocnemius. Thirty-four male habitual rearfoot strike runners were recruited and randomized divided into gait training group and control group. The medial gastrocnemius morphological properties were measured using an ultrasound device before and after training. A two-way repeated measures ANOVA (group × time) was used for analysis. The significance level was set as 0.05. The results found that after 12-week gait retraining, there was no significant group main effect and interaction effect for all parameters. A main effect of time was observed in the fascicle length (p = 0.016) and normalized fascicle length (p = 0.026). After training, the fascicle length for the GR and CON groups significantly increased by 8.5% (GR) and 2.2% (CON), and the normalized fascicle length increased by 8.8% (GR) and 2.0% (CON). It was indicated that both gait retraining and running training effectively increase the fascicle length of the medial gastrocnemius, thereby providing potential means of increasing the velocity of muscle contraction and reducing the risk of a calf strain while running

FATIGUE AFFECTS THE FREQUENCY CONTENT OF THE GROUND REACTION FORCES, BUT NOT MAGNITUDE, IN DROP LANDING TASKS

The aim of this study was to investigate the changes in the lower extremity kinematics, ground reaction forces, and frequency content of the vertical ground reaction forces between two fatigue protocols in a landing task. Eight trained male participants were instructed to perform drop-jump landings before and after two randomly fatigue protocols, namely, long-term running and functional short-term fatigue protocols. We found that the functional short-term fatigue protocol would induce an increase in hip and knee flexion, which resulted in a more flexed landing posture. Furthermore, the functional short-term fatigue protocol would decrease amplitudes in lower frequencies while increasing amplitudes in higher frequencies. These results will provide a preliminary reference for the selection of fatigue protocols in laboratory tests

Effects of 12-week gait retraining on plantar flexion torque, architecture, and behavior of the medial gastrocnemius in vivo

Objective:This study aims to explore the effects of 12-week gait retraining (GR) on plantar flexion torque, architecture, and behavior of the medial gastrocnemius (MG) during maximal voluntary isometric contraction (MVIC).Methods:Thirty healthy male rearfoot strikers were randomly assigned to the GR group (n = 15) and the control (CON) group (n = 15). The GR group was instructed to wear minimalist shoes and run with a forefoot strike pattern for the 12-week GR (3 times per week), whereas the CON group wore their own running shoes and ran with their original foot strike pattern. Participants were required to share screenshots of running tracks each time to ensure training supervision. The architecture and behavior of MG, as well as ankle torque data, were collected before and after the intervention. The architecture of MG, including fascicle length (FL), pennation angle, and muscle thickness, was obtained by measuring muscle morphology at rest using an ultrasound device. Ankle torque data during plantar flexion MVIC were obtained using a dynamometer, from which peak torque and early rate of torque development (RTD50) were calculated. The fascicle behavior of MG was simultaneously captured using an ultrasound device to calculate fascicle shortening, fascicle rotation, and maximal fascicle shortening velocity (Vmax).Results:After 12-week GR, 1) the RTD50 increased significantly in the GR group (p = 0.038), 2) normalized FL increased significantly in the GR group (p = 0.003), and 3) Vmax increased significantly in the GR group (p = 0.018).Conclusion:Compared to running training, GR significantly enhanced the rapid strength development capacity and contraction velocity of the MG. This indicates the potential of GR as a strategy to improve muscle function and mechanical efficiency, particularly in enhancing the ability of MG to generate and transmit force as well as the rapid contraction capability. Further research is necessary to explore the effects of GR on MG behavior during running in vivo

The clinical relevance of oliguria in the critically ill patient : Analysis of a large observational database

Funding Information: Marc Leone reports receiving consulting fees from Amomed and Aguettant; lecture fees from MSD, Pfizer, Octapharma, 3 M, Aspen, Orion; travel support from LFB; and grant support from PHRC IR and his institution. JLV is the Editor-in-Chief of Critical Care. The other authors declare that they have no relevant financial interests. Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Urine output is widely used as one of the criteria for the diagnosis and staging of acute renal failure, but few studies have specifically assessed the role of oliguria as a marker of acute renal failure or outcomes in general intensive care unit (ICU) patients. Using a large multinational database, we therefore evaluated the occurrence of oliguria (defined as a urine output 16 years) patients in the ICON audit who had a urine output measurement on the day of admission were included. To investigate the association between oliguria and mortality, we used a multilevel analysis. Results: Of the 8292 patients included, 2050 (24.7%) were oliguric during the first 24 h of admission. Patients with oliguria on admission who had at least one additional 24-h urine output recorded during their ICU stay (n = 1349) were divided into three groups: transient - oliguria resolved within 48 h after the admission day (n = 390 [28.9%]), prolonged - oliguria resolved > 48 h after the admission day (n = 141 [10.5%]), and permanent - oliguria persisting for the whole ICU stay or again present at the end of the ICU stay (n = 818 [60.6%]). ICU and hospital mortality rates were higher in patients with oliguria than in those without, except for patients with transient oliguria who had significantly lower mortality rates than non-oliguric patients. In multilevel analysis, the need for RRT was associated with a significantly higher risk of death (OR = 1.51 [95% CI 1.19-1.91], p = 0.001), but the presence of oliguria on admission was not (OR = 1.14 [95% CI 0.97-1.34], p = 0.103). Conclusions: Oliguria is common in ICU patients and may have a relatively benign nature if only transient. The duration of oliguria and need for RRT are associated with worse outcome.publishersversionPeer reviewe

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Effects of Two Fatigue Protocols on Impact Forces and Lower Extremity Kinematics during Drop Landings: Implications for Noncontact Anterior Cruciate Ligament Injury

The purpose of the study was to determine the effects of fatigue on the impact forces and sagittal plane kinematics of the lower extremities in a drop landing task. 15 male collegiate athletes were recruited. Five successful trials of a drop landing task were obtained during prefatigue and postfatigue in two fatigue protocols (constant speed running fatigue protocol [R-FP] and shuttle running + vertical jumping fatigue protocol [SV-FP]). Duration time, maximal heart rate, and RPE of each protocol were measured separately. Kinematic measures of the hip, knee, and ankle joints at different times coupled with peak impact force and loading rate were acquired. Our results showed a more flexed landing posture due to an increase in hip and knee flexion angles in the postfatigue condition. However, no differences in peak impact force and loading rate were found between pre- and postfatigue conditions. The changes were similar between protocols, but the SV-FP showed a significantly shorter exercise duration time than the R-FP. Fatigued athletes in this study demonstrated altered motor control strategies during a drop landing task, which may be an intentional or unintentional protective strategy for preventing themselves from potential ACL injury

Relationships between Foot Morphology and Foot Muscle Strength in Healthy Adults

The purpose of this study was to investigate if measurements of foot morphology in sitting and standing positions can predict foot muscle strength. Twenty-six healthy male adults were recruited, and their foot morphology and foot muscle strength were measured. Foot morphological variables, toe flexor strength, and metatarsophalangeal joint flexor strength were measured by using a digital caliper, Ailitech-AFG500 dynameter and metatarsophalangeal joint flexor strength tester, respectively. Partial correlation and multivariate stepwise regression were used to explore the relationships between foot morphology and toe/metatarsophalangeal joint strength. Results adjusted by age and body mass index were as follows: (1) truncated foot length in sitting and standing positions and foot width in standing position were positively correlated with the flexor strength of the first toe; (2) foot length, foot width, and truncated foot length in both positions were positively related to the flexor strength of the other toes; (3) arch height index in sitting position and differences in navicular height were negatively associated with the flexor strength of the other toes; (4) differences in foot width were negatively associated with metatarsophalangeal joint flexor strength; and (5) the multivariate stepwise regression model showed that truncated foot length in sitting position, navicular height in standing position, differences in navicular height, foot width in sitting position, and differences in foot width were significantly correlated with toe/metatarsophalangeal joint flexor strength. Simple measurements of foot morphological characteristics can effectively predict foot muscle strength. Preliminary findings provided practical implications for the improvement of the foot ability by making specific foot muscle training sessions in professional sports and by compensating the predicted muscle strength defects to prevent foot injury

Does Shoe Collar Height Influence Ankle Joint Kinematics and Kinetics in Sagittal Plane Maneuvers?

The Objective of the study is to investigate the effects of basketball shoes with different collar heights on ankle kinematics and kinetics and athletic performance in different sagittal plane maneuvers. Twelve participants who wore high-top and low-top basketball shoes (hereafter, HS and LS, respectively) performed a weight-bearing dorsiflexion (WB-DF) maneuver, drop jumps (DJs), and lay-up jumps (LJs). Their sagittal plane kinematics and ground reaction forces were recorded using the Vicon motion capture system and Kistler force plates simultaneously. Moreover, ankle dorsiflexion and plantarflexion angles, moment, power, stiffness, and jump height were calculated. In the WB-DF test, the peak ankle dorsiflexion angle (p = 0.041) was significantly smaller in HS than in LS. Additionally, the peak ankle plantarflexion moment (p = 0.028) and power (p = 0.022) were significantly lower in HS than in LS during LJs but not during DJs. In both jumping maneuvers, no significant differences were found in the jump height or ankle kinematics between the two shoe types. According to the WB-DF test, increasing shoe collar height can effectively reduce the ankle range of motion in the sagittal plane. Although the HS did not restrict the flexion–extension performance of the ankle joint during two jumping maneuvers, an increased shoe collar height can reduce peak ankle plantarflexion moment and peak power during the push-off phase in LJs. Therefore, a higher shoe collar height should be used to circumvent effects on the partial kinetics of the ankle joint in the sagittal plane

Effects of Exercise-Induced Fatigue on Lower Extremity Joint Mechanics, Stiffness, and Energy Absorption during Landings

The aim of this study was to determine the effects of two fatigue protocols on lower-limb joint mechanics, stiffness and energy absorption during drop landings. Fifteen male athletes completed landing tasks before and after two fatigue protocols (constant speed running [R-FP] and repeated shuttle sprint plus vertical jump [SJ-FP]). Sagittal plane lower-limb kinematics and ground reaction forces were recorded. Compared with R-FP, SJ-FP required significantly less intervention time to produce a fatigue state. The ranges of motion (RoM) of the hip were significantly greater when the athletes were fatigued for both protocols. Knee RoM significantly increased after SJ-FP but not after R-FP (p > 0.05), whereas the RoM of the ankle was significantly greater after R-FP but lower after SJ-FP. When fatigued, the first peak knee extension moment was significantly greater in R-FP but lower in SJ-FP; the second peak ankle plantar flexion moment was lower, regardless of protocols. After fatigue, vertical, hip, and knee stiffness was lower, and more energy was absorbed at the hip and knee for both protocols. Hip and knee extensors played a crucial role in altering movement control strategies to maintain similar impact forces and to dissipate more energy through a flexed landing posture when fatigued compared to when non-fatigued. Furthermore, SJ-FP seems to be a more efficient method to induce fatigue due to less intervention time than R-FP