scholarly journals Effect of Speed and Gradient on Plantar Force When Running on an AlterG® Treadmill.

2020 ◽  
Author(s):  
Athol Thomson ◽  
Rodney Whiteley ◽  
Clint Hansen ◽  
Julius Welzel ◽  
Sebastien Racinais ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Random Order ◽  
Force Sensor ◽  
Treadmill Running ◽  
Return To Play ◽  
Healthy Male ◽  
Rehabilitation Programs ◽  
Spatiotemporal Parameters ◽  
Plantar Force ◽  
Level Running

Abstract Background Anti-gravity treadmills are used to decrease musculoskeletal loading during treadmill running often in return to play rehabilitation programs. The effect different gradients (uphill/downhill running) have on kinetics and spatiotemporal parameters when using an AlterG® treadmill is unclear with previous research focused on level running only. Methods Ten well-trained healthy male running athletes ran on the AlterG® treadmill at varying combinations of bodyweight support (60%, 80%, and 100% BW), speed (12 km/hr, 15 km/hr, 18 km/hr, 21 km/hr, and 24 km/hr), and gradients (-15% decline, -10, -5, 0, + 5, +10 + 15% incline), representing a total of 78 conditions performed in random order. Maximum plantar force and contact time were recorded using a wireless in-shoe force sensor insole system. Results Regression analysis showed a linear relationship for maximum plantar force with bodyweight support and running speeds for level running (p < 0.0001, adj. R² = 0.604). The linear relationship, however, does not hold for negative gradients at speeds 12 & 15 km/h, with a relative ‘dip’ in maximum plantar force across all assisted bodyweight settings. Conclusions Maximum plantar force peaks are larger with faster running and smaller with more AlterG® assisted bodyweight support (athlete unweighing). Gradient made little difference except for a downhill grade of -5% decreasing force peaks as compared to level or uphill running.

scholarly journals Effect of speed and gradient on plantar force when running on an AlterG® treadmill

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Athol Thomson ◽  
Rodney Whiteley ◽  
Clint Hansen ◽  
Julius Welzel ◽  
Sebastien Racinais ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Random Order ◽  
Force Sensor ◽  
Treadmill Running ◽  
Return To Play ◽  
Healthy Male ◽  
Rehabilitation Programs ◽  
Spatiotemporal Parameters ◽  
Plantar Force ◽  
Level Running

Abstract Background Anti-gravity treadmills are used to decrease musculoskeletal loading during treadmill running often in return to play rehabilitation programs. The effect different gradients (uphill/downhill running) have on kinetics and spatiotemporal parameters when using an AlterG® treadmill is unclear with previous research focused on level running only. Methods Ten well-trained healthy male running athletes ran on the AlterG® treadmill at varying combinations of bodyweight support (60, 80, and 100% BW), speed (12 km/hr., 15 km/hr., 18 km/hr., 21 km/hr., and 24 km/hr), and gradients (− 15% decline, − 10, − 5, 0, + 5, + 10 + 15% incline), representing a total of 78 conditions performed in random order. Maximum plantar force and contact time were recorded using a wireless in-shoe force sensor insole system. Results Regression analysis showed a linear relationship for maximum plantar force with bodyweight support and running speeds for level running (p < 0.0001, adj. R2 = 0.604). The linear relationship, however, does not hold for negative gradients at speeds 12 & 15 km/h, with a relative ‘dip’ in maximum plantar force across all assisted bodyweight settings. Conclusions Maximum plantar force peaks are larger with faster running and smaller with more AlterG® assisted bodyweight support (athlete unweighing). Gradient made little difference except for a downhill grade of − 5% decreasing force peaks as compared to level or uphill running.

scholarly journals ECG Holter analysis to detect induced deconditioning on cardiac activity in bedridden volunteers

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
S Solbiati ◽  
A Paglialonga ◽  
L Costantini ◽  
E.G Caiani
Keyword(s):  
Electrical Activity ◽  
Cardiac Activity ◽  
Bed Rest ◽  
Funding Source ◽  
Healthy Male ◽  
Tukey Test ◽  
T Wave ◽  
Rehabilitation Programs ◽  
Cardiac Electrical Activity ◽  
Ethical Approval

Abstract Introduction Prolonged bed rest (BR) is an unnatural state, often related to hospitalization, chronic diseases and ageing, inducing reduced functional capacity in multiple body systems, possibly leading to cardiovascular deconditioning. We hypothesized that measuring this decline over time could represent the first step for the formulation of appropriate countermeasures or rehabilitation programs while in the hospital. Accordingly, our aim was to assess the effects of 10-day horizontal BR on cardiac electrical activity. Methods Ten healthy male volunteers (23±5 years) were enrolled in an hospital, after ethical approval and signed consent, to participate to a 10-day strict horizontal BR campaign, preceded and followed by 2 days in the facility, respectively as acclimatization and recovery. The 12-leads 24-hours Holter ECG (1000 Hz, H12+, Mortara Instrument Inc.) was acquired 1 day before BR (PRE), the 5th (BR5) and 10th day (BR10) of bedridden immobilization. From each recording, beat-to-beat RR and QTend interval series, as well as T wave amplitude (Tamp) and upslope (Tslope) were computed. Statistical analysis was applied to test changes induced by BR (ANOVA with Tukey test, p&lt;0.05), separately for day (7:00–23:00) and night (23:00–7:00) periods. Results Daily RR and QTend duration increased during BR, with peak changes at BR5 compared to PRE (+13.3% and +3% respectively), and were still prolonged at BR10 (+12.6% and +2.6%). During the night, while RR increased (BR5:+5.3%; BR10:+1.3%), QTend was found progressively shortened (BR5: −1.6%; BR10: −2.9%). Also, day and night Tamp (BR10: −19.5%) and Tslope (BR10 day: −17.1%; night: −7.8%) were found progressively reduced with the duration of BR. Conclusion During BR, cardiac electrical activity is affected by 10-days bedridden immobilization. Noticeably, a mismatch in RR-QTend relation was visible at night, where vagal autonomic system activity is prevailing. Funding Acknowledgement Type of funding source: Other. Main funding source(s): Agenzia Spaziale Italiana (ASI)

scholarly journals Definition of Metrics to Evaluate Cochlear Array Insertion Forces Performed with Forceps, Insertion Tool, or Motorized Tool in Temporal Bone Specimens

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Yann Nguyen ◽  
Guillaume Kazmitcheff ◽  
Daniele De Seta ◽  
Mathieu Miroir ◽  
Evelyne Ferrary ◽  
...  
Keyword(s):  
Temporal Bone ◽  
Electrode Array ◽  
Random Order ◽  
Lateral Wall ◽  
Force Sensor ◽  
Insertion Force ◽  
Minimal Trauma ◽  
Force Profile ◽  
Definition Of ◽  
Temporal Bones

Introduction. In order to achieve a minimal trauma to the inner ear structures during array insertion, it would be suitable to control insertion forces. The aim of this work was to compare the insertion forces of an array insertion into anatomical specimens with three different insertion techniques: with forceps, with a commercial tool, and with a motorized tool.Materials and Methods. Temporal bones have been mounted on a 6-axis force sensor to record insertion forces. Each temporal bone has been inserted, with a lateral wall electrode array, in random order, with each of the 3 techniques.Results. Forceps manual and commercial tool insertions generated multiple jerks during whole length insertion related to fits and starts. On the contrary, insertion force with the motorized tool only rose at the end of the insertion. Overall force momentum was 1.16 ± 0.505 N (mean ± SD,n=10), 1.337 ± 0.408 N (n=8), and 1.573 ± 0.764 N (n=8) for manual insertion with forceps and commercial and motorized tools, respectively.Conclusion. Considering force momentum, no difference between the three techniques was observed. Nevertheless, a more predictable force profile could be observed with the motorized tool with a smoother rise of insertion forces.

Kinetic and Kinematic Effects of Asymmetrical Loading of the Lower Limb During High-Speed Running

2021 ◽  
pp. 1-6
Author(s):  
Katrin S. Acker ◽  
Tim V.M. Eberle ◽  
Dustin J. Oranchuk ◽  
Shelley N. Diewald ◽  
Aaron M. Uthoff ◽  
...  
Keyword(s):  
Lower Limb ◽  
High Speed ◽  
Reaction Force ◽  
Random Order ◽  
Return To Play ◽  
External Loading ◽  
Maximal Velocity ◽  
Step Frequency ◽  
Cross Sectional ◽  
Running Biomechanics

Context: Light lower-limb wearable resistance has little effect on running biomechanics. However, asymmetrical wearable resistance may potentially alter the kinetics and kinematics of high speed, enabling greater loading or unloading of an injured or rehabilitative lower limb. Design: A cross-sectional study design was used to quantify the influence of asymmetric calf loading on the kinematics and kinetics during 90% maximum sprinting velocity. Methods: Following a familiarization session, 12 (male = 7 and female = 5) physically active volunteers ran at 90% of maximal velocity. In random order, participants ran with zero (0) wearable resistance and with loads of 300 g (L300) and 600 g (L600) fixed to one shank. A nonmotorized treadmill quantified vertical and horizontal kinetics and step kinematics. The kinetics and kinematics of the loaded (L0, L300, and L600) and unloaded (UL; UL0, UL300, and UL600) limbs were compared. Results: Vertical step ground reaction force of the loaded limb tended to increase between unloaded and 300 and 600 conditions (effect size [ES] = 0.48 to 0.76, all P ≤ .12), while the horizontal step force of the UL tended to decrease (ES = 0.54 to 1.32, all P ≤ .09) with greater external loading. Step length increased in the UL in 0 versus 300 and 600 conditions (ES = 0.60 to 0.70, all P ≤ .06). Step frequency decreased in the ULs in unloaded versus 300 and 600 conditions (ES = 0.73 to 1.10, all P ≤ .03). Mean step velocity tended to be greater in the ULs than the 300 and 600 conditions (ES = 0.52 to 1.01, all P ≤ .10). Only 4 of 16 variables were significantly different between the 300 and 600 conditions. Conclusions: Asymmetrical shank resistance could be used during high-speed running to reduce or increase the kinetic loading of an injured/rehabilitative limb during return to play protocols. Asymmetrical wearable resistance could also be used to alter step kinematics in runners with known asymmetries. Finally, meaningful alterations in high-speed running biomechanics can be achieved with only 300 g of shank loading.

Relative Contribution of Skin and Core Temperatures to Vasoconstriction and Shivering Thresholds during Isoflurane Anesthesia 

1999 ◽  
Vol 91 (2) ◽  
pp. 422-429 ◽  
Author(s):  
Rainer Lenhardt ◽  
Robert Greif ◽  
Daniel I. Sessler ◽  
Sonja Laciny ◽  
Angela Rajek ◽  
...  
Keyword(s):  
Linear Regression ◽  
Skin Temperature ◽  
Linear Relation ◽  
Random Order ◽  
Mean Skin Temperature ◽  
Healthy Male ◽  
Central Venous ◽  
Isoflurane Anesthesia ◽  
Proportionality Constant ◽  
Relative Contribution

Background Thermoregulatory control is based on both skin and core temperatures. Skin temperature contributes approximately 20% to control of vasoconstriction and shivering in unanesthetized humans. However, this value has been used to arithmetically compensate for the cutaneous contribution to thermoregulatory control during anesthesia--although there was little basis for assuming that the relation was unchanged by anesthesia. It even remains unknown whether the relation between skin and core temperatures remains linear during anesthesia. We therefore tested the hypothesis that mean skin temperature contributes approximately 20% to control of vasoconstriction and shivering, and that the contribution is linear during general anesthesia. Methods Eight healthy male volunteers each participated on 3 separate days. On each day, they were anesthetized with 0.6 minimum alveolar concentrations of isoflurane. They then were assigned in random order to a mean skin temperature of 29, 31.5, or 34 degrees C. Their cores were subsequently cooled by central-venous administration of fluid at approximately 3 degrees C until vasoconstriction and shivering were detected. The relation between skin and core temperatures at the threshold for each response in each volunteer was determined by linear regression. The proportionality constant was then determined from the slope of this regression. These values were compared with those reported previously in similar but unanesthetized subjects. Results There was a linear relation between mean skin and core temperatures at the vasoconstriction and shivering thresholds in each volunteer: r2 = 0.98+/-0.02 for vasoconstriction, and 0.96+/-0.04 for shivering. The cutaneous contribution to thermoregulatory control, however, differed among the volunteers and was not necessarily the same for vasoconstriction and shivering in individual subjects. Overall, skin temperature contributed 21+/-8% to vasoconstriction, and 18+/-10% to shivering. These values did not differ significantly from those identified previously in unanesthetized volunteers: 20+/-6% and 19+/-8%, respectively. Conclusions The results in anesthetized volunteers were virtually identical to those reported previously in unanesthetized subjects. In both cases, the cutaneous contribution to control of vasoconstriction and shivering was linear and near 20%. These data indicate that a proportionality constant of approximately 20% can be used to compensate for experimentally induced skin-temperature manipulations in anesthetized as well as unanesthetized subjects.

scholarly journals Return to play following anterior cruciate ligament reconstruction: incorporating fatigue into a return to play functional battery. Part A: treadmill running

2019 ◽  
Vol 5 (1) ◽  
pp. e000375 ◽  
Author(s):  
Richard Connell ◽  
Ross Milne ◽  
Bruce Paton
Keyword(s):  
Anterior Cruciate Ligament ◽  
Anterior Cruciate Ligament Reconstruction ◽  
Ligament Reconstruction ◽  
Cruciate Ligament ◽  
Treadmill Running ◽  
Return To Play ◽  
Cruciate Ligament Reconstruction ◽  
Significant Difference ◽  
Movement Strategy ◽  
Anterior Cruciate

BackgroundThe risk of reinjury and other sequelae following anterior cruciate ligament reconstruction (ACLR) remains high. Lack of knowledge regarding factors contributing to these risks limits our ability to develop sensitive return to play (RTP) tests. Using a running task, we evaluate whether fatigue induces alterations in foot progression angle (FPA), a proposed biomechanical risk factor and could be used to enhance RTP test sensitivity.MethodTransverse plane foot kinematics (FPA) were assessed for 18 post-ACLR subjects during a treadmill running task, before and after a generalised lower limb fatigue protocol. Subject’s contralateral limbs were used as a control group.ResultsA small but significant difference between FPA for ACLR and contralateral limbs was observed before but not after fatigue. When confounding variables were considered, there was a significant difference in FPA change between ACLR and contralateral limbs from the prefatigue to postfatigue state.ConclusionsFollowing ACLR athletes may develop a knee-protective movement strategy that delays the progression of osteoarthritis in the ACL-injured knee. This may, however, increase the risk of ACL reinjury. Following the onset of fatigue this proposed movement strategy, and thus osteoarthritis protection, is lost.

scholarly journals Low urine flow reduces the capacity to excrete a sodium load in humans

1997 ◽  
Vol 273 (5) ◽  
pp. R1726-R1733 ◽  
Author(s):  
Gabriel Choukroun ◽  
François Schmitt ◽  
Franck Martinez ◽  
Tilman B. Drüeke ◽  
Lise Bankir
Keyword(s):  
Everyday Life ◽  
Flow Rate ◽  
Sodium Excretion ◽  
Random Order ◽  
Urine Flow ◽  
Healthy Male ◽  
Sodium Load ◽  
Collecting Ducts ◽  
Nacl Load ◽  
Salt Sensitive Hypertension

Recent studies in rats suggest that vasopressin and the resulting urinary concentrating activity reduce the capacity of the kidney to excrete sodium. The present study investigates the influence of the level of hydration on the excretion of a sodium load in humans. Eight healthy male volunteers (18–35 yr) were studied twice, in random order, under either low (LowH) or high (HighH) hydration. They drank throughout the study either 0.25 (LowH) or 2.0 ml water/kg body wt (HighH) every 30 min. After 1 h equilibration, urine was collected for 2 h before (basal) and 10 h after the NaCl load (5 g NaCl in 250 ml, infused intravenously over 30 min). Differences in excretory patterns between LowH and HighH were mostly confined to the first 4 h after the load. The increase in Na excretion after the load was more intense under HighH than under LowH (+10.9 ± 2.6 vs. +5.8 ± 2.7 mmol/h in the first 4 postload h; P < 0.001). Under HighH, urine flow rate (V) increased markedly (+41%), with little change in urinary Na concentration (UNa), whereas under LowH, V declined slightly and UNa rose significantly (+33%). The capacity to raise UNa seemed to reach a maximum at ≈280 mM. In both conditions, the changes in UNa observed after the load were positively correlated with basal UNa. After the load, urea excretion increased under HighH and decreased under LowH, whereas K excretion was unaffected in either condition. These results show that sodium excretion is facilitated by an abundant water supply. The less efficient sodium excretion occurring at low V is probably due to the influence of vasopressin on water, urea, and sodium movements across the collecting ducts. These observations suggest that, in everyday life, a low water intake could limit the capacity to excrete sodium. Whether this could contribute to salt-sensitive hypertension remains to be evaluated.

scholarly journals Modification of Angular Kinematics and Spatiotemporal Parameters during Running after Central and Peripheral Fatigue

2021 ◽  
Vol 11 (14) ◽  
pp. 6610
Author(s):  
Alberto Encarnación-Martínez ◽  
Pedro Pérez-Soriano ◽  
Roberto Sanchis-Sanchis ◽  
Rafael Berenguer-Vidal ◽  
Antonio García-Gallart
Keyword(s):  
Knee Flexion ◽  
Central Fatigue ◽  
Ankle Dorsiflexion ◽  
Treadmill Running ◽  
Maximum Absorption ◽  
Peripheral Fatigue ◽  
Initial Contact ◽  
Fatigue Protocol ◽  
Spatiotemporal Parameters ◽  
Stance Time

Fatigue causes kinematics modifications during running, and it could be related to injuries. The aim was to identify and compare the effects of central and peripheral fatigue on angular kinematics and spatiotemporal parameters during running. Angular kinematics and spatiotemporal parameters were evaluated using an infrared motion capture system and were registered during 2 min treadmill running in pre- and post-fatigue states in eighteen male recreational runners. Central fatigue was induced by a 30 min running fatigue protocol on a treadmill, while peripheral fatigue in quadriceps and hamstrings muscles was induced by an isokinetic dynamometer fatigue protocol. Central fatigue increased the anterior shank oscillation during the initial contact, knee flexion during the maximum absorption, posterior shank oscillation during propulsion, and stance time (p < 0.05). Peripheral fatigue decreased ankle dorsiflexion during initial contact and increased knee flexion and posterior shank oscillation during propulsion (p < 0.05). Moreover, central fatigue increased to a greater extent the hip and knee flexion and ankle dorsiflexion during initial contact and maximum absorption as well as stance time and propulsion time (p < 0.05). These results suggested that central fatigue causes greater increases in the range of movements during the midstance than peripheral fatigue.

scholarly journals Effects of Exercise Intensity on Postexercise Endothelial Function and Oxidative Stress

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Conor McClean ◽  
Ryan A. Harris ◽  
Malcolm Brown ◽  
John C. Brown ◽  
Gareth W. Davison
Keyword(s):  
Oxidative Stress ◽  
Shear Rate ◽  
Endothelial Function ◽  
Acute Exercise ◽  
Venous Blood ◽  
Random Order ◽  
Treadmill Running ◽  
Lipid Hydroperoxides ◽  
Artery Flow ◽  
And Oxidative Stress

Purpose. To measure endothelial function and oxidative stress immediately, 90 minutes, and three hours after exercise of varying intensities.Methods. Sixteen apparently healthy men completed three exercise bouts of treadmill running for 30 minutes at 55%V˙O2max(mild); 20 minutes at 75%V˙O2max(moderate); or 5 minutes at 100%V˙O2max(maximal) in random order. Brachial artery flow-mediated dilation (FMD) was assessed with venous blood samples drawn for measurement of endothelin-1 (ET-1), lipid hydroperoxides (LOOHs), and lipid soluble antioxidants.Results. LOOH increased immediately following moderate exercise (P<0.05). ET-1 was higher immediately after exercise and 3 hours after exercise in the mild trial compared to maximal one (P<0.05). Transient decreases were detected forΔFMD/ShearAUCfrom baseline following maximal exercise, but it normalised at 3 hours after exercise (P<0.05). Shear rate was higher immediately after exercise in the maximal trial compared to mild exercise (P<0.05). No changes in baseline diameter, peak diameter, absolute change in diameter, or FMD were observed following any of the exercise trials (P>0.05).Conclusions. Acute exercise at different intensities elicits varied effects on oxidative stress, shear rate, and ET-1 that do not appear to mediate changes in endothelial function measured by FMD.

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