Measuring countermovement jump (CMJ) height accurately is essential for evaluating lower-body explosive power in athletes and other active populations. With technological advancements, various portable tools have been developed for this purpose, including force platforms, contact mats, and video-based software. This study aimed to (a) investigate the test–retest reliability of the KINVENT K-Deltas force platform for CMJ height measurement and (b) compare its accuracy with a contact mat (Chronojump, Spain) and a video-based software (My Jump app, version 3). Twenty-two physically active collegiate athletes (mean age of 19.7 ± 1.2 years) from various sports backgrounds completed five CMJ trials with simultaneous height measurements using all three tools. Intra-class correlation coefficients (ICC), Cronbach’s alpha, and coefficient of variation (CV) were calculated to assess reliability. In contrast, Pearson correlations and Bland–Altman plots were used to compare device results. The K-Deltas force platform exhibited high test–retest reliability (ICC = 0.981), closely matching the contact mat (ICC = 0.987) and the My Jump app (ICC = 0.986). Correlations between the instruments were strong (force platform vs. contact mat: r = 0.987; force platform vs. My Jump: r = 0.987; contact mat vs. My Jump: r = 0.996), with no between-instrument differences (t-test p = 0.203–0.935, effect size ≤ 0.01–0.16), demonstrating the interchangeability of these tools for practical purposes. However, Bland–Altman analysis revealed limits of agreement between the devices, indicating small but consistent measurement differences. While all instruments were reliable, discrepancies in the absolute values suggest practitioners should consider device-specific variations when comparing CMJ data. These findings highlight the reliability of the K-Deltas force platform as a viable alternative for measuring CMJ height, though differences between devices should be accounted for in applied settings. Therefore, the portable force plates can monitor training, predict injury risk, assess neuromuscular fatigue, and lead to informed decision-making.

The purpose of this study was to compare the effects of a six-week contrast training intervention conducted twice per week during the preparatory period on the measures of physical fitness in university-level male soccer players. Materials and methods. Sixteen players were selected as participants and randomly assigned to an experimental group or an active control group. Data were collected at baseline and after a six-week training intervention period for 15 m and 30 m linear sprint, medicine ball throw (MBT), standing long jump (SLJ), countermovement jump (CMJ), change of direction speed (CODS), peak torque (both legs) during extension and flexion, and running-based anaerobic sprint test (RAST). Results. The analysis revealed reported significant small to very-large magnitude within-group improvement in all the dependent variables for the experimental group (p<0.001–0.028) but not for the control group (p=0.066–1.000). Further, the analysis of covariance with the pre-test scores as covariates revealed significant differences at post-intervention assessments for all the dependent variables, favoring the contrast training group (p<0.001–0.05). Conclusions. A six-week contrast training intervention with two weekly sessions during the preparatory period may be sufficient to induce small improvement in the 30 m linear sprint and isokinetic strength of both legs, moderate improvement in the 15 m linear sprint, and MBT, large improvements in SLJ, RAST, and a very large improvement in vertical jump (CMJ) and CODS.

Introduction Biceps curl is one of the most traditional and highly popular weight training exercise that target the muscles of the upper arm (Biceps Brachii muscle). There are many variations of this exercise that can be used to design a training schedule for the best result. Objective This study aimed at analyzing the muscle activation of Biceps Brachii and Brachioradialis muscles while performing different biceps curl exercises with the same load. Novelty To the best of our knowledge none of the studies has analyzed the muscle activation of Biceps Brachii and Brachioradialis muscles with the selected exercises. Material and Method Ten healthy subjects (20.8 ± 1.75 years) performed 70% of 1 repetition maximum (RM) for eight different biceps curl exercises. Surface Electro Myo Graphy (SEMG) was used to measure muscle electrical activity that occurs during muscular contraction. Results and Discussions The results of the study shows that, in case of muscles activation in Biceps Brachii, except supine narrow grip Z curl (SNGZC) and prone lying biceps curl (PLBC), all the other exercises reveal significant differences with the concentrated curl (CC). No statistical difference was observed when comparing the muscle activation of Brachioradialis muscle in the eight different biceps curl exercises. Application It will help the professional trainers and coaches to design training schedule for all level of Athletes which may consist of different variations of the biceps exercises. Conclusion Concentrated curl is a more effective exercise for activation of biceps muscles as compared to other exercises with the same load. All the selected biceps exercises have the same effect on activating the Brachioradialis Muscles.