Age-Related Reductions in Muscle Quality Influence the Relative Differences in Strength and Power

Examination of muscle morphology and neuromuscular function in normal weight and overfat children aged 7‐10 years

“…An interesting finding of the current study is the greater rate of decline in PT SLOPE across isokinetic velocities in the OF, which was related to mEI, an indirect assessment of intramuscular fat, but not mCSA. These findings are consistent with recent findings in older adults . Classically, a decline in PT with increments in velocity is attributed to the unloading of fibers that primarily express slow‐twitch characteristics .…”

“…These findings are consistent with recent findings in older adults. 8 Classically, a decline in PT with increments in velocity is attributed to the unloading of fibers that primarily express slow-twitch characteristics. 38 Therefore, PT at faster velocities reflects the strength of fibers that possess rapid shortening velocities.…”

“…It is hypothesized that leg extensor mCSA will be larger in overfat children due to increases in intramuscular fat that is reflected by an increase in mEI; however, these differences would be removed when normalized to mEI (ie, mCSA/mEI). Lastly, given the findings of Gerstner et al, mCSA and mEI may provide insight into specific mechanisms contributing to the possible differences in torque production capabilities from slow to fast isokinetic velocities between normal and overfat children.…”

“…7 Furthermore, these changes may also influence torque production capabilities from slow to fast isokinetic velocities. 8 Recent studies have demonstrated that both mCSA and echo intensity (mEI) can be reliably examined using panoramic ultrasound imaging. 9 mCSA is frequently used to examine training-and aging-related differences in muscle size, 10,11 whereas echo intensity (mEI) provides information regarding muscle tissue composition or non-contractile tissue infiltration within the muscle.…”

“…However, it is possible that the increases in muscle cross‐sectional area (mCSA) may be due to alterations in intramuscular fat . Furthermore, these changes may also influence torque production capabilities from slow to fast isokinetic velocities …”