Acute effects of unilateral and bilateral conditioning activity on countermovement jump, linear speed, and muscle stiffness: A randomized crossover study.

PURPOSE: Evidence directly comparing the effects of bilateral and unilateral conditioning activities is limited. Therefore, the aim of this study was to assess the acute effect of unilateral and bilateral conditioning activity on vastus lateralis stiffness, countermovement jump parameters, and 10 m sprint. METHODS: Twelve semi-professional basketball players participated in this study (age: 23 ± 4 yrs; body mass: 84.7 ± 10.6 kg; body height: 192 ± 6 cm; basketball training experience: 11 ± 4 yrs) performed four experimental sessions to compare the acute effects of bilateral, stronger-only, weaker-only lower limb or no conditioning activity on vastus lateralis stiffness, countermovement jumps variables (height; peak velocity; peak force, contraction time, countermovement depth, and modified reactive strength index and 10 m sprint time. Measurements were performed 5 minutes before and in the 5th and 10th minutes after CA. RESULTS: Bilateral conditioning activity significantly increase the countermovement jump height (p = 0.002; ES = 0.71) and the reactive strength index modified (p = 0.010; ES = 0.59). Moreover, a significantly higher peak force in the stronger than in the weaker limb was found (p<0.001) without any differences between conditions and time points (p>0.05). However, there were no significant (p>0.05) interactions and effects of conditions or time-point in the case of the other countermovement jump variables, vastus lateralis stiffness, and 10m sprint time. CONCLUSION: Unilateral and bilateral drop jumps (3 sets of 5 repetitions) did not affect the vastus lateralis stiffness and time of the 10m sprint. However, only bilateral drop jumps effectively enhanced the countermovement jump height and modified reactive strength index. Bilateral drop jumps might be a useful part of a warm-up to improve jumping performance in basketball players.

Modification of Strength Training Programs in Handball Players and its Influence on Power During the Competitive Period.

A high level of muscle power is necessary for the effective use of technique during handball competitions. The presented research concentrated on comparing the effectiveness of two training modes directed towards the development of muscle power - plyometric and traditional strength training. Furthermore, we evaluated whether resistance training performed twice a week was sufficient to guarantee an increase in muscle power of handball players. We also investigated whether strength training designed according to the "waving" model (one training session per week oriented towards the development of maximal strength and one towards the development of power) was sufficient to increase muscle power in handball players. The study included 28 professional handball players who were divided into 3 groups: Group 1 subjected to additional strength training (8 individuals), Group 2 subjected to traditional plyometric training (8 individuals) and Group 3 following standard training (12 individuals). Research was conducted at the beginning and at the end of the 1st round of competitions and consisted of the following measurements: CMJ (countermovement jump) and SJ (squat jump), a 10-s trial on a cycle-ergometer and ball-throwing velocity. Analysis of the results showed that both the plyometric and strength training programs induced a statistically significant increase in jumping height and generated power during the CMJ. The group subjected to additional strength training achieved greater increases in CMJ power than the group carrying out plyometric training, which in case of the CMJ peak power turned out to be statistically significant (p < 0.05). Different results were obtained when studying changes in the flight speed of the thrown ball; the group undergoing plyometric training registered minor increases (significant in the standing throw ), and there were decreases in the flight speed of the thrown ball (significant in the leaning back throw) in the group following the traditional strength training program.