The effects of resistance training to near volitional failure on motor unit recruitment during neuromuscular fatigue.

Background: It is unclear whether chronically training close to volitional failure influences motor unit recruitment strategies during fatigue.

Purpose: We compared resistance training to near volitional failure . non-failure on individual motor unit action potential amplitude (MUAP) and surface electromyographic excitation (sEMG) during fatiguing contractions.

A comparison of techniques to determine active motor threshold for transcranial magnetic stimulation research.

The determination of active motor threshold (AMT) is a critical step in transcranial magnetic stimulation (TMS) research. As AMT is frequently determined using an absolute electromyographic (EMG) threshold (e.g.

Task-specific resistance training adaptations in older adults: comparing traditional and functional exercise interventions.

Muscle strength declines ∼3% per year after the age of 70. Resistance training guidelines for older adults are often based on free-weight and machine exercises, which may be inaccessible and lack carryover to activities of daily living. We tested the hypothesis that resistance training adaptations in older adults are task-specific.

Combined action observation and mental imagery versus neuromuscular electrical stimulation as novel therapeutics during short-term knee immobilization.

Limb immobilization causes rapid declines in muscle strength and mass. Given the role of the nervous system in immobilization-induced weakness, targeted interventions may be able to preserve muscle strength, but not mass, and vice versa. The purpose of this study was to assess the effects of two distinct interventions during 1 week of knee joint immobilization on muscle strength (isometric and concentric isokinetic peak torque), mass (bioimpedance spectroscopy and ultrasonography), and neuromuscular function (transcranial magnetic stimulation and interpolated twitch technique).

fNIRS is capable of distinguishing laterality of lower body contractions.

The use of functional near-infrared spectroscopy (fNIRS) for brain imaging during human movement continues to increase. This technology measures brain activity non-invasively using near-infrared light, is highly portable, and robust to motion artifact. However, the spatial resolution of fNIRS is lower than that of other imaging modalities.

Sex differences in muscle-quality recovery following one week of knee joint immobilization and subsequent retraining.

This manuscript represents the second phase of a clinical trial designed to examine the effects of knee joint immobilization and retraining on muscle strength and mass. In Phase 2, we examined sex differences in the recovery of multiple indices of muscle quality after a resistance training-based rehabilitation program. Following 1 week of immobilization, 27 participants (16 males, 11 females) exhibiting weakness underwent twice weekly resistance training sessions designed to re-strengthen their left knee.

A comparison of techniques for verifying the accuracy of precision decomposition-derived relationships between motor unit firing rates and recruitment thresholds from surface EMG signals.

Approaches for validating motor unit firing times following surface electromyographic (EMG) signal decomposition with the precision decomposition III (PDIII) algorithm have not been agreed upon. Two approaches have been common: (1) "reconstruct-and-test" and (2) spike-triggered averaging (STA). We sought to compare motor unit results following the application of these approaches.

Sex-Specific Reliability of Lower-Limb Corticospinal Excitability and Silent Periods.

Pagan, JI, Harmon, KK, Girts, RM, MacLennan, RJ, Beausejour, JP, Hernandez-Sarabia, JA, Coker, NA, Carr, JC, Ye, X, DeFreitas, JM, and Stock, MS. Sex-specific reliability of lower-limb corticospinal excitability and silent periods. J Strength Cond Res 37(9): 1882-1887, 2023-Transcranial magnetic stimulation (TMS) is a research tool that has potential to provide new insights into strength training-induced adaptations.

The effects of resistance training to near failure on strength, hypertrophy, and motor unit adaptations in previously trained adults.

Limited research exists examining how resistance training to failure affects applied outcomes and single motor unit characteristics in previously trained individuals. Herein, resistance-trained adults (24 ± 3 years old, self-reported resistance training experience was 6 ± 4 years, 11 men and 8 women) were randomly assigned to either a low-repetitions-in-reserve (RIR; i.e.

The acute effects of action observation on muscle strength/weakness and corticospinal excitability in older adults.

Muscle weakness is a critical problem facing many older adults. Interventions targeting nervous system plasticity may show promise in enhancing strength. The purpose of this study was to examine the acute effects of action observation on muscular strength characteristics and corticospinal excitability in older adults.

The influence of ultrasound image depth and gain on skeletal muscle echo intensity.

Echo intensity may associate with indicators of skeletal muscle quality, but investigators often use different methodological approaches that may alter echo intensity when acquiring B-mode ultrasound images. We examined the influence of image depth and gain settings on the interpretation of echo intensity. Thirty-six college-aged males and females participated.

The Influence of Sonographer Experience on Skeletal Muscle Image Acquisition and Analysis.

The amount of experience with ultrasonography may influence measurement outcomes while images are acquired or analyzed. The purpose of this study was to identify the interrater reliability of ultrasound image acquisition and image analysis between experienced and novice sonographers and image analysts, respectively. Following a brief hands-on training session (2 h), the experienced and novice sonographers and analysts independently performed image acquisition and analyses on the biceps brachii, vastus lateralis, and medial gastrocnemius in a sample of healthy participants ( = 17).