Direct Relationship Between Proton T2 and Exercise Intensity in Skeletal Muscle MR Images

Fisher, M. J.; Meyer, Ronald A.; Adams, Gregory R.; Foley, Jeanne M.; Potchen, E. James

doi:10.1097/00004424-199005000-00003

Cited by 241 publications

(269 citation statements)

References 0 publications

Supporting

Mentioning

241

Contrasting

Unclassified

Order By: Relevance

“…Fatigue of the VL necessitated greater use of the VM and RF, as reflected by contrast shift in MR images, to perform the submaximal KEE. The fact that exercise-induced contrast shifts in T2-weighted images correlate with integrated EMG activity (1), increase with exercise intensity (1,2,21,30,33,36), and relate to isometric torque with EMS (2) supports the notion of greater use of these two QF muscles for the second rather than the first bout of KEE. These responses are considered to be acute modifications of neuromuscular coordination among the synergistic muscles to perform the exercise.…”

Section: Discussionmentioning

confidence: 92%

“…The KEE was performed at the MRI facility to permit image collection immediately after exercise (1,2,6,7,14,21,(33)(34)(35). Subjects performed four sets of 10 repetitions of concentric (extension phase)-eccentric (flexion phase) contractions with a load equal to 50% of the 4 ϫ 10 RM with the use of a plate-loaded knee extension machine (Badger-Magnum, Milwaukee, WI).…”

Section: Subjectsmentioning

confidence: 99%

“…Standard spin-echo MR images of the left thigh were taken using a 1.5-T super-conducting magnet (Signa, General Electric, Milwaukee, WI) essentially as done previously (1,2,6,7,14,21,(33)(34)(35). Thirteen 10-mm-thick transaxial images (repetition time ϭ 1,500 ms; echo time ϭ 30 and 60 ms) of the left thigh spaced 10 mm apart were collected using 1.0 number of excitations with a whole body coil.…”

Section: Subjectsmentioning

confidence: 99%

“…Whereas magnetic resonance (MR) imaging (MRI) has been used to acquire anatomical information (4,5,22), use of human skeletal muscle has also been assessed with exercise-induced contrast shift in transverse relaxation time (T2) of MR images (1-3, 6, 7, 14, 21, 33-35, 42). It has been demonstrated that this contrast shift is correlated with integrated EMG activity (1), related to isometric torque induced by electromyostimulation (EMS) (2), increases with exercise intensity (1,2,21,26,30,33,36) and the metabolic state of skeletal muscle (37,40,42), and can discriminate use among relatively small synergistic muscles (13,14) and neuromuscular compartments (3). Thus exerciseinduced contrast shift in MR images seemed ideal to assess neuromuscular plasticity among synergists.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

Akima

Foley

Prior³

et al. 2002

Journal of Applied Physiology

Self Cite

View full text Add to dashboard Cite

. Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans. J Appl Physiol 92: 679-684, 2002; 10.1152/ japplphysiol.00267.2001.-This study tested the hypothesis that fatigue of a single member of musculus quadriceps femoris (QF) would alter use of the other three muscles during knee extension exercise (KEE). Six men performed KEE with the left QF at a load equal to 50% of the 4 ϫ 10 repetitions maximum. Subsequently, electromyostimulation (EMS), intended to stimulate and fatigue the left m. vastus lateralis (VL), was applied for 30 min. Immediately after EMS, subjects repeated the KEE. Transverse relaxation time (T2)-weighted magnetic resonance images were taken before and after each bout of KEE and at 3 and 30 min of EMS to assess use and stimulation, respectively, of the QF. T2 of each of the QF muscles was increased 8-13% after the first KEE. During EMS, T2 increased (P Ͻ 0.05) even more in VL (10%), whereas it decreased (P Ͻ 0.05) to pre-KEE levels in m. vastus medials (VM) and m. rectus femoris (RF). The VL and, to some extent, the m. vastus intermedius were stimulated, whereas the VM and RF were not, thereby recovering from the first bout of KEE. Isometric torque, initially 30% of maximal voluntary, was reduced to 13% at 3 min and 7% at 30 min. T2 was greater (P Ͻ 0.05) after the second than the first bout of KEE, especially the increase for the VM and RF. These results suggest that subjects were able to perform the second bout with little contribution of the VL by greater use of the other QF muscles. The simplest explanation is increased central command to the QF such that the intended act could be accomplished despite acute fatigue of one of its synergists.

show abstract

Section: Discussionmentioning

confidence: 92%

Section: Subjectsmentioning

confidence: 99%

Section: Subjectsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

Akima

Foley

Prior³

et al. 2002

Journal of Applied Physiology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Most present studies have used a monoexponential transverse relaxativity analysis, although a multiexponential behavior has been described (24). The monoexponential proton transverse relaxation time (T2) of skeletal muscle is known to increase by exercise (6,20). Increased intracellular water content (4,18) and mechanisms related to aerobic capacity, e.g., net intramuscular accumulation of osmoles (22), are assumed to be the most important factors related to prolonged T2 with exercise.…”

mentioning

confidence: 99%

Water exchange induced by unilateral exercise in active and inactive skeletal muscles

Nygren

Kaijser

2002

Journal of Applied Physiology

View full text Add to dashboard Cite

Nygren, Anders T., and Lennart Kaijser. Water exchange induced by unilateral exercise in active and inactive skeletal muscles. J Appl Physiol 93: [1716][1717][1718][1719][1720][1721][1722] 2002. First published August 9, 2002; 10.1152/japplphysiol.01117. 2001.-Water exchange was evaluated in active (E-leg) and inactive skeletal muscles by using 1 H-magnetic resonance imaging. Six healthy subjects performed one-legged plantar flexion exercise at low and high workloads. Magnetic resonance imaging measured calf cross-sectional area (CSA), transverse relaxation time (T2), and apparent diffusion capacity (ADC) at rest and during recovery. After high workload, inactive muscle decreased CSA and T2 by 2.1% (P Ͻ 0.05) and 3.1% (P Ͻ 0.05), respectively, and left ADC unchanged. E-leg simultaneously increased CSA, T2, and ADC by 4.2% (P Ͻ 0.001), 15.5% (P Ͻ 0.05), and 12.5% (P Ͻ 0.001), respectively. In conclusion, ADC and T2 correlated highly with muscle volume, indicative of extravascular water displacement closely related to muscle activity and perfusion, which was presumably a combined effect of increased intracellular osmoles and hydrostatic forces as driving forces. A distinguishable muscle temperature release was initially detected in the E-leg after high workload, and the ensuing recovery of ADC and T2 indicated delayed interstitial restitution than restitution of the intracellular compartment. Furthermore, absorption of extravascular water was detected in inactive muscles at contralateral high-intensity exercise.diffusion; magnetic resonance imaging; tissue water; transverse relaxation time MAGNETIC RESONANCE IMAGING (MRI) can be applied on local skeletal muscle regions by analyzing variables pixel by pixel or within multiple local regions, including active as well as less active muscles (31). Therefore, simultaneous evaluation of water exchange in active and inactive muscles during dynamic exercise is valuable to elucidate the signal shift in muscle that is related to exercise and is beneficial to study how different MRI techniques that focus on water displacement relate.The physics of water exchange in the skeletal muscle is highly complex and multifactorial. The magnetic resonance signal has been shown to be multiexponential, which indicates a multicompartmental origin. 1 H-MRI using transverse relaxativity focuses on the intrinsic property of water and its exchange between the different compartments as well as the binding capacity of the water molecule to subcellular structures (11). Most present studies have used a monoexponential transverse relaxativity analysis, although a multiexponential behavior has been described (24). The monoexponential proton transverse relaxation time (T2) of skeletal muscle is known to increase by exercise (6,20). Increased intracellular water content (4, 18) and mechanisms related to aerobic capacity, e.g., net intramuscular accumulation of osmoles (22), are assumed to be the most important factors related to prolonged T2 with exercise. To what degree other factors such as H ϩ , p...

show abstract

Measurement and analysis of nonexponential signal decay curves in brain diffusion and muscle relaxation magnetic resonance studies in humans

Zengingönül

Mulkern

1999

Int. J. Imaging Syst. Technol.

View full text Add to dashboard Cite

Detailed measurement and analysis of two important processes in magnetic resonance imaging (MRI) are described. The processes of interest are the apparent diffusion coefficient (ADC) behavior of water protons in the brain and the transverse relaxation (T2) behavior of water protons in muscle. The method described for the brain water diffusion study allows for more detailed sampling of the brain signal decay with b‐factor than is usually performed. Prolonged scan times are avoided using a line scan format with the tradeoff being reduced volume coverage. The method described for the muscle studies also provides greater sampling of the T2 decay curves than is generally performed. The main advantage of the line scan format in this case, however, lies in the ability to perform “single‐shot” sampling of the decay curve which may prove useful for studying temporal changes of muscle during exercise. In either case, the high sampling of the relevant decay curves allows us to explore the limits of the usual assumption of monoexponential decay with two complimentary computational methods. These are discrete and continuum exponential signal modeling, respectively. For both processes studied, the assumption of monoexponential decay is found lacking. The results indicate the potential for greater tissue characterization and highlight the need for biophysical modeling of multicomponent decay behavior in vivo. © 1999 John Wiley & Sons, Inc. Int J Imaging Syst Technol 10, 294–303, 1999

show abstract

Direct Relationship Between Proton T2 and Exercise Intensity in Skeletal Muscle MR Images

Cited by 241 publications

References 0 publications

Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

Water exchange induced by unilateral exercise in active and inactive skeletal muscles

Measurement and analysis of nonexponential signal decay curves in brain diffusion and muscle relaxation magnetic resonance studies in humans

Contact Info

Product

Resources

About