As neuromuscular performance assessment has become a fundamental component of athlete monitoring, ensuring strong measurement reliability is essential for supporting accurate data-driven decision-making. Thus, the purpose of this study was twofold: (i) to examine the reliability of countermovement vertical jump (CMJ) force-time metrics obtained using a portable force plate system (Hawkin Dynamics) and (ii) to determine whether absolute and relative reliability scores differ between well-trained individuals (i.e., athletes) and those less familiar with CMJ force-plate testing (i.e., non-athletes). Seventy-four participants volunteered to take part in this investigation, of whom thirty-nine were NCAA Division-I baseball and track-and-field athletes and thirty-five age-matched non-athletes with no prior CMJ testing experience on force plates. After performing a standardized dynamic warm-up, participants performed three CMJs without arm swing while standing on a dual uniaxial force plate system sampling at 1000 Hz. Each jump trial was separated by a 30 s rest interval. Absolute and relative reliability were assessed using the coefficient of variation (CV) and intraclass correlation coefficient (ICC), respectively. The results revealed that 75% of the variables demonstrated excellent reliability. Specifically, absolute (CV < 10%) and relative (ICC > 0.750) reliability values were good to excellent for most force-time metrics of interest, including braking and propulsive phase duration, peak braking force, average propulsive power, reactive strength index-modified, countermovement depth, and jump height. In contrast, average and peak landing force and inter-limb asymmetry measures during the braking and propulsive phases displayed moderate to good reliability, whereas asymmetry-related variables during the landing phase exhibited poor reliability. In addition, athletes demonstrated lower CV and greater ICC across most metrics compared to non-athletes.

Ortega, DG, Smith, RW, Arnett, JE, Neltner, TJ, Roberts, TD, Pioske, JS, Schmidt, RJ, and Housh, TJ. Wavelet-based electromyographic and mechanomyographic intensity responses to fatiguing tasks anchored to a rating of perceived exertion versus torque. J Strength Cond Res XX(X): 000–000, 2026—This study used wavelet analyses to examine the effects of anchor scheme on electromyographic (EMG) and mechanomyographic (MMG) intensity. Twelve men (age = 20.9 ± 2.2 years) performed maximal voluntary isometric contractions (MVICs) before and after sustained, isometric forearm flexion tasks anchored to a rating of perceived exertion (RPE) of 4 (RPE4 _FT ) and the torque (TRQ4 _FT ) that corresponded to an RPE of 4. Wavelet analyses were used to decompose the EMG and MMG signals recorded from the biceps brachii during the MVICs onto sets of 11 nonlinearly scaled Cauchy wavelets. Repeated measures analyses of variance were used to analyze the EMG and MMG intensity data, with significance set at p ≤ 0.05. After the RPE4 _FT , EMG intensity decreased ( p = 0.004 to 0.047) at wavelet bands 5 and 8–11. After the TRQ4 _FT , EMG intensity increased ( p = 0.009) at wavelet band 1 and decreased ( p < 0.001 to p = 0.047) at wavelet bands 5–11. The MMG intensity distribution across the 11 wavelet bands did not differ ( p > 0.05) between the sustained tasks and remained unchanged from pretest to post-test MVIC. Taken together, the EMG and MMG intensity responses suggested that, despite the presence of peripheral fatigue, which affected the TRQ4 _FT to a greater extent than the RPE4 _FT , motor units were maximally recruited with no change in their firing rates from pretest to post-test MVIC. Thus, the application of wavelet-based spectral analyses offers a sensitive approach for detecting subtle changes in muscle function, which has important implications for advancing diagnostic precision and developing targeted interventions in sports performance, rehabilitation, and clinical assessments of neuromuscular health.

This study: (1) Determined the time course of early-phase adaptations in average peak torque (APT), the rate of velocity development (RVD), and average power (AP) following very short-term unilateral, reciprocal, concentric isokinetic forearm extension and flexion training in untrained women; and (2) determine whether training the non-dominant arm induced cross-education adaptations in the dominant, non-trained arm. Twelve untrained women (age: 21.7 ± 1.2 yrs) completed four testing and four training visits (pre-test and following 2, 3, and 4 days of training). The testing consisted of three maximal repetitions of the dominant and non-dominant arms at 60°, 180°, and 300°·s⁻¹, with APT and AP calculated as the average of the 3 repetitions and RVD as the fastest repetition. The training consisted of 6 sets of 10 maximal repetitions at 180°·s⁻¹ with the non-dominant arm. The differences in mean values across testing visits for APT, AP, and RVD were determined by separate 2 (Arm) × 2 (Muscle Action) × 3 (Velocity) × 4 (Time [across all testing visits]) repeated measures ANOVA (α ≤ 0.05) with Bonferroni-corrected post hoc comparisons. For the trained arm, there were increases in APT (p < 0.001) following four training visits and AP following three (p = 0.006) and four (p = 0.004) training visits. Furthermore, following four training visits, RVD (collapsed across Arms and Muscle Action) decreased at 180°·s⁻¹ (p = 0.002) and 300°·s⁻¹ (p = 0.005) following four training visits. There were no changes in APT or AP (p = 0.155–1.000) in the non-trained arm, which indicated no cross-education adaptations. These findings suggested that 3–4 days of moderate-velocity, unilateral, reciprocal, isokinetic training elicited early-phase adaptations for APT, RVD, and AP in untrained women, while cross-education adaptations for APT and AP were not observed within this timeframe.