Effect of 4 weeks of plyometric training in the pre-competitive period on volleyball athletes' performance.

We aimed to evaluate the effect of 4 weeks of plyometric training (PT), performed in the pre-competitive period, on the vertical jump performance of professional volleyball athletes. We recruited 17 professional female volleyball players (age: 19 ± 3 years; weight: 67.2 ± 5.50 kg; height: 1.81 ± 0.22 m; body fat: 14.4 ± 2.12%; squat 1RM test: 75.5 ± 7.82 kg; training time experience: 6.2 ± 3.4 years) to participate in four weeks of training and assessments. They were divided into an experimental group (EG = 9) and a control group (CG = 8). Both groups were submitted to friendly matches, technical, tactical and resistance training (4 weeks/˜9 sessions per week), and internal load monitoring was carried out. The EG performed PT twice a week. At the beginning and end of the four weeks, jump tests were performed. The main findings are: 1) PT when incorporated into the pre-competitive period can induce greater improvements in jumping performance (EG = 28.93 ± 3.24 cm to 31.67 ± 3.39 cm; CG = 27.91 ± 4.64 cm to 28.97 ± 4.58 cm; when comparing the percentage delta, we found a difference between groups with ES of 1.04 and P = 0.02); 2) this result is observed when the training load is similar between groups and increases over the weeks, respecting the linear progression principle. Therefore, including plyometric training in the preparatory period for volleyball, with low monotony and training strain increment, is an effective strategy for further CMJ performance improvement.

Caffeine supplementation improves physical performance without affecting fatigue level: a double-blind crossover study.

This study examined the effect of caffeine supplementation (CAFF) in a Wingate test (WT), and the behaviour of blood lactate concentrations (BLa) and neuromuscular fatigue (NMF), measured as reduced countermovement jump (CMJ) performance, in response to the WT. In a double-blind crossover study, 16 participants attended the laboratory twice, separated by a 72-hour window. In the sessions, participants first ingested 6 mg·kg-1 of either CAFF or placebo (PLAC), and then performed a WT. BLa was measured before (L-pre), and 0.5 min (L-post-0.5) and 3.5 min (L-post-3.5) after conducting the WT. The CMJ test was conducted before (CMJ pre), after (CMJ post), and 3 min after completing (CMJ post-3) the WT. The results indicated that CAFF enhanced peak power (Wpeak: + 3.22%; p = 0.040), time taken to reach Wpeak (T_Wpeak: -18.76%; p = 0.001) and mean power (Wmean: + 2.7%; p = 0.020). A higher BLa was recorded for CAFF at L-post-0.5 (+ 13.29%; p = 0.009) and L-post-3.5 (+ 10.51%; p = 0.044) compared to PLAC. CAFF improved peak power (PP; + 3.44%; p = 0.003) and mean power (MP; + 4.78%; p = 0.006) at CMJ pre, compared to PLAC, whereas PP and MP were significantly diminished at CMJ post and CMJ post-3 compared to pre (p < 0.001 for all comparisons) under both the CAFF and PLAC conditions. PP and MP were increased at post-3 compared to post (p < 0.001 for all comparisons) for both conditions. In conclusion, CAFF increased WT performance and BLa without affecting NMF measured by CMJ. Thus, CAFF may allow athletes to train with higher workloads and enhance the supercompensation effects after an adequate recovery period.

Different Shoulder Exercises Affect the Activation of Deltoid Portions in Resistance-Trained Individuals.

The aims of this study were to compare muscle activity of the anterior deltoid, medial deltoid, and posterior deltoid in the bench press, dumbbell fly, shoulder press, and lateral raise exercises. Thirteen men experienced in strength training volunteered for the study. Muscle activation was recorded during maximum isometric voluntary contraction (MVIC) for data normalization, and during one set of 12 repetitions with the load of 60% 1RM in all exercises proposed. One-way repeated-measures ANOVA with Bonferroni's posthoc was applied using a 5% significance level. For anterior deltoid, the shoulder press (33.3% MVIC) presented a significantly higher level of activation when compared to other exercises. Also, no significant difference was found between the bench press (21.4% MVIC), lateral raise (21.2% MVIC), and dumbbell fly (18.8% MVIC). For the medial deltoid, the lateral raise (30.3% MVIC) and shoulder press (27.9% MVIC) presented a significantly higher level of activity than the bench press (5% MVIC) and dumbbell fly (3.4% MVIC). Besides, no significant difference was found between the bench press and the dumbbell fly. For the posterior deltoid, the lateral raise (24% MVIC) presented a significantly higher level of activation when compared to other exercises. For the posterior deltoid portion, the shoulder press (11.4% MVIC) was significantly more active than the bench press (3.5% MVIC) and dumbbell fly (2.5% MVIC). Moreover, no significant difference was found between the bench press and the dumbbell fly. In conclusion, the shoulder press and lateral raise exercises showed a higher level of muscle activation in the anterior deltoid and medial deltoid when compared to the bench press and dumbbell fly exercises.

Cardiovascular Responses to Unilateral, Bilateral, and Alternating Limb Resistance Exercise Performed Using Different Body Segments.

Moreira, OC, Faraci, LL, de Matos, DG, Mazini Filho, ML, da Silva, SF, Aidar, FJ, Hickner, RC, and de Oliveira, CEP. Cardiovascular responses to unilateral, bilateral and alternating limb resistance exercise performed using different body segments. J Strength Cond Res 31(3): 644-652, 2017-The aim of this study was to verify and compare the cardiovascular responses to unilateral, bilateral, and alternating limb resistance exercise (RE) performed using different body segments. Fifteen men experienced in RE were studied during biceps curls, barbell rows, and knee extension exercises when performed bilaterally, unilaterally, and using alternating limbs. The protocol consisted of 3 sets of 10 repetitions at 80% of 10 repetition maximum with 2-minute rest between sets. Heart rate (HR) and blood pressure (BP) were measured after the last repetition. There was a statistically significant increase in HR, systolic blood pressure (SBP), and rate pressure product (RPP), from rest to postexercise. The RPP was higher in the third set of all exercises and in all 3 forms of execution, when compared with the first set. Bilateral biceps curls caused a greater increase in RPP (first and second sets) and HR, compared with the same exercise performed unilaterally. Furthermore, the performance of bilateral biceps curls induced greater HR and RPP, in all sets, compared with bilateral knee extension and barbell rows. There was also a significantly higher SBP for the alternating second and third sets and also for the bilateral third set of the knee extensions as compared with the barbell rows. It was concluded from the data of this study that the cardiovascular response was increased from rest to postexercise in all forms of exercise, especially immediately after the third set of RE. For exercises performed bilaterally with the upper body (biceps curls), there was a greater cardiovascular response when compared with the same exercise performed unilaterally or with lower-body exercise performed bilaterally.