Background: Velocity-based training (VBT) requires precise measurement devices to monitor neuromuscular performance. PowerTrack^TM is a novel optoelectronic device designed to assess movement velocity in resistance training. This study aimed to evaluate the validity and reliability of PowerTrack^TM during the Smith machine back squat. Methods: Twenty experienced-trained men performed three repetitions at three submaximal loads (20, 50, and 70 kg) across two sessions. Velocity metrics—mean velocity (MV), mean propulsive velocity (MPV), and maximum velocity (Vmax)—were simultaneously recorded by PowerTrack^TM and the criterion device (MuscleLab^TM). Validity was assessed via ordinary least products (OLP) regression, Lin’s concordance correlation coefficient (CCC), and Bland–Altman plots. Reliability was determined using intraclass correlation coefficients (ICCs), standard error of measurement (SEM), coefficient of variation (CV), and minimum detectable change (MDC). Results: PowerTrack showed high agreement with MuscleLab^TM for MPV and Vmax (slope ≈ 1.00; CCC = 0.95–0.97), while MV presented a proportional bias (slope = 0.83). ICCs ranged from 0.78 to 0.91 across loads, and SEM remained <0.09 m/s for all metrics, indicating excellent relative reliability and acceptable absolute precision. Conclusion: Despite a slight underestimation of MV at light loads, PowerTrack^TM proved to be a valid and reliable device for velocity monitoring in VBT contexts.

Objective: To evaluate changes in the isokinetic concentric moment of the knee extensors and the moment–velocity curve during the application of no BFR compared to superimposed BFR. Methods: A total of 37 physically active adults [33.73 (10.96) years; 11 females] performed three sets of isokinetic concentric knee extensions, each including three angular velocities (300°/s, 210°/s, and 120°/s; BIODEX dynamometer). BFR at 40% (BFR40) and 80% (BFR80) of the maximal pressure occlusion (MPO) were applied randomly after an equal control protocol without BFR (BFR0). Results: No significant differences were found for any interaction between the BFR condition and angular velocity (p > 0.05); 109.78 ± 32.90 vs. 71.24 ± 11.18, 116.68 ± 27.29 vs. 74.40 ± 15.11, and 113.91 ± 28.43 vs. 72.95 ± 13.76 Nm at 300°/s; 137.60 ± 35.27 vs. 88.85 ± 15.23, 135.40 ± 33.04 vs. 86.32 ± 17.38, and 132.68 ± 31.99 vs. 85.39 ± 16.25 Nm at 210°/s; 177.62 ± 41.40 vs. 114.72 ± 20.10, 166.40 ± 45.39 vs. 198.14 ± 21.80, and 162.60 ± 40.10 vs. 109.09 ± 18.90 Nm at 120°/s, for BFR0, BFR40, and BFR80, respectively. There were significant differences in the interactions by gender. Conclusions: Superimposed application of BFR at 40% MPO and 80% MPO during an isokinetic knee extension did not cause any acute change in the ability to produce maximal moment or power. The use of BFR may not generate an ergogenic effect that is sufficient to cause acute changes in force production.

Background: Accurate monitoring of eccentric phase velocity is needed to support velocity-based training (VBT), yet field-valid tools for multi-joint exercises are scarce. This study evaluated the concurrent validity and reliability of an optoelectronic device to quantify eccentric phase velocity during the Smith machine back squat. Methods: A total of 20 resistance-trained men completed two sessions and performed three repetitions at three submaximal loads (20, 50, and 70 kg). Eccentric mean velocity and peak velocity (Vmax) were recorded simultaneously using PowerTrack^TM and a criterion system (MuscleLab^TM). Validity was assessed using ordinary least products regression, Lin’s concordance correlation coefficient (CCC), and Bland–Altam analysis. Reliability was examined via intraclass correlation coefficients (ICC), standard error of measurement (SEM), coefficient of variation, and minimum detectable change. Results: Agreement between devices was very high for Vmax (slope ≈ 1.00; CCC = 0.95), with a small constant bias. Eccentric mean velocity showed proportional bias under higher velocity conditions, whereas overall concordance remained high (CCC = 0.95). Inter-session reliability was excellent (ICC = 0.87–0.96), with low SEM values for eccentric velocity metrics. Conclusions: PowerTrack^TM can be a valid and reliable tool for monitoring eccentric phase velocity during the Smith machine back squat, with Vmax representing the most robust metric for applied eccentric VBT.