Designing and Usability testing of a New Prototype Active Footrest for Knee Extension Exercise Among Office Workers

We hypothesized that a period of endurance training would result in a speeding of muscle phosphocreatine concentration ([PCr]) kinetics over the fundamental phase of the response and a reduction in the amplitude of the [PCr] slow component during high-intensity exercise. Six male subjects (age 26 ± 5 yr) completed 5 wk of single-legged knee-extension exercise training with the alternate leg serving as a control. Before and after the intervention period, the subjects completed incremental and high-intensity step exercise tests of 6-min duration with both legs separately inside the bore of a whole-body magnetic resonance spectrometer. The time-to-exhaustion during incremental exercise was not changed in the control leg [preintervention group (PRE): 19.4 ± 2.3 min vs. postintervention group (POST): 19.4 ± 1.9 min] but was significantly increased in the trained leg (PRE: 19.6 ± 1.6 min vs. POST: 22.0 ± 2.2 min; P < 0.05). During step exercise, there were no significant changes in the control leg, but end-exercise pH and [PCr] were higher after vs. before training. The time constant for the [PCr] kinetics over the fundamental exponential region of the response was not significantly altered in either the control leg (PRE: 40 ± 13 s vs. POST: 43 ± 10 s) or the trained leg (PRE: 38 ± 8 s vs. POST: 40 ± 12 s). However, the amplitude of the [PCr] slow component was significantly reduced in the trained leg (PRE: 15 ± 7 vs. POST: 7 ± 7% change in [PCr]; P < 0.05) with there being no change in the control leg (PRE: 13 ± 8 vs. POST: 12 ± 10% change in [PCr]). The attenuation of the [PCr] slow component might be mechanistically linked with enhanced exercise tolerance following endurance training.

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Kinetics of V̇o2 and femoral artery blood flow during heavy-intensity, knee-extension exercise

Journal of Applied Physiology ◽

10.1152/japplphysiol.00707.2004 ◽

2005 ◽

Vol 99 (2) ◽

pp. 683-690 ◽

Cited By ~ 14

Author(s):

Nicole D. Paterson ◽

John M. Kowalchuk ◽

Donald H. Paterson

Keyword(s):

Blood Flow ◽

Femoral Artery ◽

Time Course ◽

Slow Component ◽

Knee Extension ◽

Artery Blood Flow ◽

Phase 2 ◽

Femoral Artery Blood Flow ◽

Knee Extension Exercise ◽

Kinetics Of

It has been suggested that, during heavy-intensity exercise, O2 delivery may limit oxygen uptake (V̇o2) kinetics; however, there are limited data regarding the relationship of blood flow and V̇o2 kinetics for heavy-intensity exercise. The purpose was to determine the exercise on-transient time course of femoral artery blood flow (Q̇leg) in relation to V̇o2 during heavy-intensity, single-leg, knee-extension exercise. Five young subjects performed five to eight repeats of heavy-intensity exercise with measures of breath-by-breath pulmonary V̇o2 and Doppler ultrasound femoral artery mean blood velocity and vessel diameter. The phase 2 time frame for V̇o2 and Q̇leg was isolated and fit with a monoexponent to characterize the amplitude and time course of the responses. Amplitude of the phase 3 response was also determined. The phase 2 time constant for V̇o2 of 29.0 s and time constant for Q̇leg of 24.5 s were not different. The change (Δ) in V̇o2 response to the end of phase 2 of 0.317 l/min was accompanied by a ΔQ̇leg of 2.35 l/min, giving a ΔQ̇leg-to-ΔV̇o2 ratio of 7.4. A slow-component V̇o2 of 0.098 l/min was accompanied by a further Q̇leg increase of 0.72 l/min (ΔQ̇leg-to-ΔV̇o2 ratio = 7.3). Thus the time course of Q̇leg was similar to that of muscle V̇o2 (as measured by the phase 2 V̇o2 kinetics), and throughout the on-transient the amplitude of the Q̇leg increase achieved (or exceeded) the Q̇leg-to-V̇o2 ratio steady-state relationship (ratio ∼4.9). Additionally, the V̇o2 slow component was accompanied by a relatively large rise in Q̇leg, with the increased O2 delivery meeting the increased V̇o2. Thus, in heavy-intensity, single-leg, knee-extension exercise, the amplitude and kinetics of blood flow to the exercising limb appear to be closely linked to the V̇o2 kinetics.

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Can Hip Joint Position affect Quadriceps Muscle Responses during Knee Extension Exercise?

International Journal of Sports Medicine ◽

10.1055/a-1179-8374 ◽

2020 ◽

Vol 41 (13) ◽

pp. 929-935

Author(s):

Denis César Leite Vieira ◽

Marco Aurélio Araujo Dourado ◽

Lucas Ugliara ◽

Joao Luiz Quagliotti Durigan ◽

Brad J. Schoenfeld ◽

...

Keyword(s):

Vastus Lateralis ◽

Muscle Thickness ◽

Rectus Femoris ◽

Peak Torque ◽

Quadriceps Muscle ◽

Knee Extension ◽

Knee Extensors ◽

Work Output ◽

Before And After ◽

Knee Extension Exercise

AbstractThis study investigated the acute effects of seated and supine knee extension exercise on muscle swelling, torque, and work output. Twelve resistance-trained men performed two isokinetic concentric-only knee-extension training protocols at different hip positions in a counter-balanced order. They completed the knee extension exercise in the seated (hip angle at 85°) and supine (hip angle at 180°) positions. The torque and work output were assessed during each set. Moreover, muscle thickness of the middle and proximal vastus lateralis and rectus femoris were evaluated before and after each protocol and used as an indicator of muscle swelling. Middle rectus femoris and proximal vastus lateralis thickness increased significantly (p=0.01) with no difference between exercise variations. However, the middle vastus lateralis thickness increased (p=0.01) only after the seated knee extension exercise (~7%). Knee extensors’ peak torque and work output were approximately 8% higher (p=0.04) in the seated when compared to the supine hip position. There was a similar decrease in torque and work output throughout both protocols (p=0.98). In conclusion, seated knee extension exercises produced greater torque, work output, and muscle swelling in the vastus lateralis when compared to the supine knee extension exercise.

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Discrepancy between femoral and capillary blood flow kinetics during knee extension exercise

Respiratory Physiology & Neurobiology ◽

10.1016/j.resp.2015.08.005 ◽

2015 ◽

Vol 219 ◽

pp. 69-77 ◽

Cited By ~ 1

Author(s):

S.J. Schlup ◽

C.J. Ade ◽

R.M. Broxterman ◽

T.J. Barstow

Keyword(s):

Blood Flow ◽

Knee Extension ◽

Capillary Blood ◽

Capillary Blood Flow ◽

Knee Extension Exercise

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Graft Tension During Active Knee Extension Exercise in Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction

Arthroscopy The Journal of Arthroscopic and Related Surgery ◽

10.1016/j.arthro.2009.07.016 ◽

2010 ◽

Vol 26 (2) ◽

pp. 214-222 ◽

Cited By ~ 14

Author(s):

Tatsuo Mae ◽

Konsei Shino ◽

Norinao Matsumoto ◽

Akira Maeda ◽

Ken Nakata ◽

...

Keyword(s):

Anterior Cruciate Ligament ◽

Anterior Cruciate Ligament Reconstruction ◽

Ligament Reconstruction ◽

Cruciate Ligament ◽

Knee Extension ◽

Double Bundle ◽

Cruciate Ligament Reconstruction ◽

Graft Tension ◽

Anterior Cruciate ◽

Knee Extension Exercise

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Mitochondrial respiration in creatine-loaded muscle: is there 31P-MRS evidence of direct effects of phosphocreatine and creatine in vivo?

Journal of Applied Physiology ◽

10.1152/japplphysiol.01269.2005 ◽

2006 ◽

Vol 100 (4) ◽

pp. 1428-1430 ◽

Cited By ~ 7

Author(s):

Graham Kemp

Keyword(s):

Respiration Rate ◽

Mitochondrial Respiration ◽

Strong Relationship ◽

Knee Extension ◽

Resonance Spectroscopy ◽

Direct Effects ◽

The Relationship ◽

Knee Extension Exercise ◽

Moderate Relationship

Recent human isolated muscle fiber studies suggest that phosphocreatine (PCr) and creatine (Cr) concentrations play a role in the regulation of mitochondrial respiration rate. To determine whether similar regulatory mechanisms are present in vivo, this study examined the relationship between skeletal muscle mitochondrial respiration rate and end-exercise PCr, Cr, PCr-to-Cr ratio (PCr/Cr), ADP, and pH by using 31P-magnetic resonance spectroscopy in 16 men and women (36.9 ± 4.6 yr). The initial PCr resynthesis rate and time constant (Tc) were used as indicators of mitochondrial respiration after brief (10–12 s) and exhaustive (1–4 min) dynamic knee extension exercise performed in placebo and creatine-supplemented conditions. The results show that the initial PCr resynthesis rate has a strong relationship with end-exercise PCr, Cr, and PCr/Cr ( r > 0.80, P < 0.001), a moderate relationship with end-exercise ADP ( r = 0.77, P < 0.001), and no relationship with end-exercise pH ( r = −0.14, P = 0.34). The PCr Tc was not as strongly related to PCr, Cr, PCr/Cr, and ADP ( r < 0.77, P < 0.001–0.18) and was significantly influenced by end-exercise pH ( r = −0.43, P < 0.01). These findings suggest that end-exercise PCr and Cr should be taken into consideration when PCr recovery kinetics is used as an indicator of mitochondrial respiration and that the initial PCr resynthesis rate is a more reliable indicator of mitochondrial respiration compared with the PCr Tc.

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