Ght time (FT) and double integration of vertical reaction force (DIF) methods in the estimation of vertical jump height with the video method (VID) as reference; (b) to verify the degree of agreement among the 3 methods; (c) to propose regression equations to predict the jump height using the FT and DIF. Twenty healthy male and female nonathlete college students participated in this study. The experiment involved positioning a contact mat (CTM) on the force platform (FP), with a video camera 3 m from the FP and perpendicular to the sagittal plane of the subject being assessed. Each participant performed 15 countermovement jumps with 60-second intervals between the trials. Significant differences were found between the jump height obtained by VID and the results with FT (p ≤ 0.01) and DIF (p ≤ 0.01), showing that the methods are not valid. Additionally, the DIF showed a greater degree of agreement with the reference method than the FT did, and both presented a systematic error. From the linear regression test was determined the prediction equations with a high degree of linearity between the methods VID vs. DIF (R2 = 0.988) and VID vs. FT (R2 = 0.979). Therefore, the prediction equations suggested may allow coaches to measure the vertical jump performance of athletes by the FT and DIF, using a CTM or an FP, which represents more practical and viable approaches in the sports field; comparisons can then be made with the results of other athletes evaluated by VID....

This study investigated the effects of changing cadence and workload on pedaling technique. Eight cyclists were evaluated during an incremental maximal cycling and two 30-minute submaximal trials at 60 % and 80 % of maximal power output (W_60 % and W_80 %, respectively). During submaximal 30-minute trials, they cycled for 10 minutes at a freely chosen cadence (FCC), 10 minutes at a cadence 20 % above FCC (FCC + 20 %), and 10 minutes at a cadence 20 % below FCC (FCC − 20 %). Pedal forces and kinematics were evaluated. The resultant force (RF), effective force (EF), index of effectiveness (IE) and IE during propulsive and recovery phase (IEprop and IErec, respectively) were computed. For W_60 %, FCC − 20 % and FCC presented higher EFmean (69 ± 9 N and 66 ± 14 N, respectively) than FCC + 20 % (52 ± 14 N). FCC presented the highest IEprop (81 ± 4 %) among the cadences (74 ± 4 and 78 ± 5 % for FCC − 20 % and FCC + 20 %, respectively). For W_80 %, FCC presented higher EFmean (81 ± 5 N) than FCC + 20 % (72 ± 10 N). The FCC − 20 % presented the lower IEprop (71 ± 7 %) among the cadences. The EFmin was higher for W_80 % than W_60 % for all cadences. The IE was higher at W_80 % (61 ± 5 %) than W_60 % (54 ± 9 %) for FCC + 20 % (all p < 0.05). Lower cadences were more effective during the recovery phase for both intensities and FCC was the best technique during the propulsive phase.

This study analyzed the effect of 4 weeks of jumping interval training (JIT), included in endurance training, on neuromuscular and physiological parameters. Eighteen recreational runners, randomized in control and experimental groups, performed 40 min of running at 70% of velocity at peak oxygen uptake, for 3 times per week. Additionally, the experimental group performed the JIT twice per week, which consisted of 4 to 6 bouts of continuous vertical jumps (30 s) with 5-min intervals. Three days before and after the training period, the countermovement (CMJ) and continuous jump (CJ₃₀), isokinetic and isometric evaluation of knee extensors/flexors, progressive maximal exercise, and submaximal constant-load exercise were performed. The JIT provoked improvement in neuromuscular performance, indicated by (i) increased jump height (4.7%; effect size (ES) = 0.99) and power output (≈3.7%; ES ≈ 0.82) of CMJ and rate of torque development of knee extensors in isometric contraction (29.5%; ES = 1.02); (ii) anaerobic power and capacity, represented by the mean of jump height (7.4%; ES = 0.8), and peak power output (PPO) (5.6%; ES = 0.73) of the first jumps of CJ₃₀ and the mean of jump height (10.2%, ES = 1.04) and PPO (9.5%, ES = 1.1), considering all jumps of CJ₃₀; and (iii) aerobic power and capacity, represented by peak oxygen uptake (9.1%, ES = 1.28), velocity at peak oxygen uptake (2.7%, ES = 1.11), and velocity corresponding to the onset of blood lactate accumulation (9.7%, ES = 1.23). These results suggest that the JIT included in traditional endurance training induces moderate to large effects on neuromuscular and physiological parameters.

Brazil has the main producers and exporters of chicken meat, which is classified as the third largest world chicken meat producer and lead exporter. This study aimed at analyzing the body discomfort perception in poultry slaughterhouse workers and its associations with the task characteristics. The study included 290 workers, 200 women (34.7±7.7 years) and 90 men (36.8±8.2 years). A body map for evaluating discomfort and an interview regarding organizational issues and criteria of the OCRA method were used. Descriptive statistics and chi-square test (p ≤ 0.05) were used. It was found that 87.6% of respondents performed repetitive tasks, 86.2% performed rest breaks, 82.8% performed job rotation (2–7 tasks) and 61% used tools. It was also found that 67.2% felt discomfort in at least one body region, and the symptoms most often reported were pain, fatigue and tingling. The body regions most frequently cited were: shoulders (62.6%), neck (46.2%), spine (36.4%), forearms (31.3%), arms (29.2%), wrists (25.6%) and hands (25.6%). In sectors artificially cold (n = 204), 54.1% felt cold. There was no association between body discomfort and gender, task characteristics, performance of rest breaks and job rotation, use of tools and time working in the company; however, there was association with cold perception (p = 0.035).