Effect of strength training on the relationship between magnetic resonance relaxation time and muscle fibre composition

Kuno, Shinya; Katsuta, Shigeru; Akisada, Masayoshi; Anno, Izumi; Matsumoto, Katsuya

doi:10.1007/bf00236690

Cited by 26 publications

(19 citation statements)

References 13 publications

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“…Thus, the data on the %activated area did not correspond to the diVerence in the muscle Wber composition among heads (Elder et al 1982). On the other hand, several studies (Aagaard et al 2001;Harber et al 2004;Kuno et al 1990;MacDougall et al 1980) found a greater hypertrophy in the type II Wbers than in the type I Wbers after chronic resistance training. Hence, the relatively small increase in the CSA in the distal region (Fig.…”

Section: Discussionmentioning

confidence: 60%

Association between regional differences in muscle activation in one session of resistance exercise and in muscle hypertrophy after resistance training

et al. 2011

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The purpose of this study was to examine if the regional difference in muscle hypertrophy after chronic resistance training is associated with muscle activation after one session of resistance exercise. Twelve men performed one session of resistance exercise of elbow extensors. Before and immediately after the exercise, transverse relaxation time (T2)-weighted magnetic resonance (MR) images of upper arm were recorded to evaluate the muscle activation along its length. In the MR images, T2 for the pixels within the triceps brachii muscle was quantified. The number of pixels with T2 greater than the threshold (mean + 1SD of T2 before the exercise) was expressed as the ratio to the number of pixels occupied by the muscle (%activated area). Another 12 subjects completed 12 weeks of training intervention (3 days per week), which consisted of the same program variables as used in the experiment for the T2 measurement. The cross-sectional areas of the triceps brachii before and after the training intervention were measured from MR images of upper arm. The %activated area of the triceps brachii induced by one session of the exercise was found to be significantly lower in the distal region than the middle and proximal regions. Similarly, the relative increase in muscle cross-sectional area after the 12 weeks of training intervention was significantly less in the distal region than the middle and proximal regions. The results suggest that the regional difference in muscle hypertrophy after chronic resistance training is attributable to the regional difference in muscle activation during the exercise.

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Section: Discussionmentioning

confidence: 60%

Association between regional differences in muscle activation in one session of resistance exercise and in muscle hypertrophy after resistance training

et al. 2011

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“…Interestingly, data from one group studying humans reported opposite findings. There, muscle proton Tl and T2 relaxation times positively correlated with the percentage of fast-twitch fibers?4,35 A subsequent study in humans found no correlation between T2 and percentage of fast-twitch fibers.77 Interestingly, that study found the correlation between muscle T1 relaxation time and the percentage of fast twitch to be negative, not positive as Kuno et al 35 reported. The negative correlation is more consistent with the findings from animal studies.…”

Section: Muscle Fiber Typingmentioning

confidence: 66%

Diagnostic Imaging of Skeletal Muscle Exercise Physiology and Pathophysiology

Shellock¹,

Tyson²,

Fleckenstein³

1996

Muscle Imaging in Health and Disease

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“…Chronic exercise conditioning may also alter MR image contrast. T 2 has been shown to vary between trained and untrained subjects (19,22) and to correlate with fiber type in resting human and rabbit muscle (20,23) .These changes in T 2 result from the dependence of relaxation on the local molecular environment of the nuclei under study (10,17). The signals used to produce the MR images in this study arise from the protons of either water or lipid.…”

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confidence: 99%

Magnetic resonance imaging and electromyography as indexes of muscle function

Adams

Duvoisin

Dudley

1992

Journal of Applied Physiology

218

213

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1992.-Electromyography (EMG) is commonly used to determine the electrical activity of skeletal muscle during contraction. To date, independent verification of the relationship between muscle use and EMG has not been provided. It has recently been shown that relaxation-(e.g., T 2 ) weighted magnetic resonance images (MRI) of skeletal muscle demonstrate exercise-induced contrast enhancement that is graded with exercise intensity. This study was conducted to test the hypothesis that exercise-induced magnetic resonance (MR) contrast shifts would relate to EMG amplitude if both measures reflect muscle use during exercise. Both MRI and EMG data were collected for separate eccentric (ECC) and concentric (CON) exercise of increasing intensity to take advantage of the fact that the rate of increase and amplitude of EMG activity are markedly greater for CON muscle actions. Seven subjects 30 ± 2 (SE) yr old performed five sets of 10 CON or ECC arm curls with each of four resistances representing 40, 60, 80, and 100% of their 10 repetition maximum for CON curls. There was 1.5 min between sets and 30 min between bouts (5 sets of 10 actions at each relative resistance) . Multiple echo, transaxial T 2 -weighted MR images (1.5 T, TR/TE 2,000/30) were collected from a 7-cm region in the middle of the arm before exercise and immediately after each bout. Surface EMG signals were collected from both heads of the biceps brachii and the long head of the triceps brachii muscles. CON and ECC actions resulted in increased integrated EMG (IEMG) and T 2 values that were strongly related (r = 0.99, P < 0.05) with relative resistance. The rate of increase and absolute value of both T 2 and IEMG were greater for CON than for ECC actions. IEMG and T 2 for both CON and ECC actions were correlated (r = 0.99, P < 0.05). The results suggest that J) surface IEMG accurately reflects the contractile behavior of muscle and 2) exercise-induced increases in MRI T 2 values reflect some processes that scale with muscle use. muscle function MAGNETIC RESONANCE SPECTROSCOPY (MRS) has become an accepted tool for in vivo biochemical studies of muscle tissue. Magnetic r esonance (MR) imaging (MRI) is a variant of this methodology that is rapidly becoming the standard for many clinical diagnostic applications because it provides unparalleled visualization of anatomic detail of soft tissues such as muscle, tendon, cartilage, and various organs. MRI has also begun to be used in basic muscle research. For example, MR images of skeletal muscle show exercise-induced contrast enhance-1578 ment, which appears to be graded with exercise intensity (7). This has been used to infer which muscles were used during the activity and the extent of their contribution.Electromyography (EMG) has long been the noninvasive method of choice for analyses of muscle activation during exercise (2). It entails sampling electrical activity from a muscle region of interest with needle or surface electrodes. There is good relation between EMG amplitude and force development for a variety of...

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Effect of strength training on the relationship between magnetic resonance relaxation time and muscle fibre composition

Cited by 26 publications

References 13 publications

Association between regional differences in muscle activation in one session of resistance exercise and in muscle hypertrophy after resistance training

Association between regional differences in muscle activation in one session of resistance exercise and in muscle hypertrophy after resistance training

Diagnostic Imaging of Skeletal Muscle Exercise Physiology and Pathophysiology

Magnetic resonance imaging and electromyography as indexes of muscle function

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