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Sedentary lifestyles reduce muscle mass, strength, power, and alter viscoelastic properties. Plyometric jump training (PJT) shows promise in countering these effects, but the optimal training volume for individuals with low athletic performance remains unclear. This study aimed to determine the minimal PJT volume required to improve muscle and tendon viscoelastic properties, strength, and power in sedentary individuals. A double-blind randomised controlled trial included 44 participants divided into three groups: Control Group (CG) (n = 16), Reduced Volume Training Group (RVTG) (n = 16), and Training Group (TG) (n = 12). The four-week PJT programme involved three weekly sessions with gradual volume increments; RVTG performed 50% less volume than TG. Baseline and follow-up assessments included the isokinetic standing up (SU) and sitting down (SD) phases at 15 cm/s and 5 cm/s, and myotonometer measurements. In the SU phase at 15 cm/s, significant differences were found (p = 0.01) with higher values in TG (10.0 ± 3.3 N/kg) compared to CG and RVTG. At 5 cm/s, differences in SD were observed (p = 0.002). For Achilles tendon properties in RVTG: stiffness (p = 0.04), decrement (p = 0.01), and relaxation (p = 0.02). A PJT volume of 2,414 jumps improved muscle strength, while 1,207 jumps altered tendon properties. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the acute effect of pre-activation with Variable Intra-Repetition Resistance and isometry on the overhead throwing velocity in handball players. Fourteen female handball players took part in the study (age: 21.2 ± 2.7 years, experience: 10.9 ± 3.5 years). For Post-Activation Potentiation, two pre-activation methods were used: (I) Variable Intra-Repetition Resistance: 1 x 5 maximum repetitions at an initial velocity of 0.6 m·s-1 and a final velocity of 0.9 m·s-1; (II) Isometry: 1 x 5 s of maximum voluntary isometric contraction. Both methods were "standing unilateral bench presses" with the dominant arm, using a functional electromechanical dynamometer. The variable analysed was the mean of the three overhead throws. Ball velocity was measured with a radar (Stalker ATS). The statistical analysis was performed using ANOVA with repeated measures. No significant differences were found for either method (variable resistance intra-repetition: p = 0.194, isometry: p = 0.596). Regarding the individual responses, the analysis showed that 86% of the sample increased throwing velocity with the variable resistance intra-repetition method, while 93% of the sample increased throwing velocity with the isometric method. Both the variable intra-repetition resistance and isometric methods show improvements in ball velocity in female handball players. However, the authors recommend checking individual responses, since the results obtained were influenced by the short rest interval between the pre-activation and the experimental sets. [ABSTRACT FROM AUTHOR]