Aim: The aim of this study was to investigate the effects of performing an isometric conditioning contraction (CC) consisting of two sets of five seconds maximal voluntary contraction in physically active individuals prior to three sets of Loaded Squat Jumps (LSJ). Method: 5 males and 4 females (mean ± SD: age 25 ± 2 years, height 175 ± 10 cm, body mass 70 ± 15 kg) were assessed on their power output, force production, jump height and velocity on three sets of LSJ on two separate sessions. Each participant attended two sessions in randomized order: a control session (CON) and an experimental session (EXP) separated by at least two hours. The EXP session consisted of a 10 min warm-up followed by 2 x 5 seconds isometric CC, this was proceeded by another two minutes of rest before three sets of LSJ were performed, each set separated by a two-minute rest. During the CON session a two-minute rest, followed by three sets of LSJ, replaced the isometric CC sequence. Results: No significant improvement was found on any of the physical parameters assessed, comparing the CON and EXP session (p > 0.05). The results showed a variance on individual response were some subjects performed better after the CC and others did not . Conclusion: In conclusion, this study evaluated the effect of performing an isometric CC prior three sets of LSJ. The results indicate that an isometric CC consisting of two sets of five seconds maximal voluntary contraction is insufficient to enhance the performance in an LSJ.

The use of the squat exercise (and its derivatives) in gym-based settings is widespread owing to perceived functional performance enhancing effects. In particular, there has been preponderance amongst practitioners with loads that maximise power outputs (Pmax) based on a perception that mechanical peak power is directly related to explosive functional performance such as sprinting ability. The optimal muscular quality associated with squats remains elusive though, mostly due to methodological limitations in the research. The four experimental studies in this thesis sought to quantify the kinetic and kinematic outputs of a machine squat-jump and their relationship to sprinting ability, both descriptively and across a training period. First, an analysis of the kinetic and kinematic outputs of a machine squat-jump across a spectrum of loads was performed, with an emphasis on power output. Then, the relationship of these outputs with sprint ability was investigated. Correlations do not imply cause and effect, thus a training intervention was undertaken to quantify the relationships of the change in performance measures over time, and allow a comparison of different training protocols. Specifically, one training group was prescribed training loads based on individually determined peak power outputs, and the other based on traditional maximal strength training loads. Because the intention of this thesis was to enhance our knowledge of best strength training practice for elite sporting performance, highly trained athletes were specifically chosen as subjects, cognizant of the population specific nature of training adaptation. In study one, it was determined that the point on the power-load spectrum where peak and mean power occurred in the machine squat-jump was 21.6 ± 7.1 %1RM (mean ± SD) and 39.0 ± 8.6 %1RM respectively although there was considerable individual variation in these points. A broad plateau in power outputs was evident for most subjects with at most a 9.9% (90% confidence limits ±2.4%) difference in peak or means power at loads up to 20 %1RM either side of the peak. Studies two and three established that, of the multiple kinetic and kinematic measures investigated, only 1RM strength, work and impulse (all relative to body mass) provided any indication of useful kinetic / kinematic outputs that were potentially worthwhile developing for enhancing sprint performance, albeit with only moderate correlations (r = ~ -0.3). Additionally, the intercorrelations between maximal strength and explosive kinetic and kinematic measures were only moderate (r = ~0.3), casting doubt on the common practice of pursuing high 1RM strength with the intention of improving explosive muscle performance. The training study provided evidence that training at the load that maximised individual peak power output was no more effective for improving sprint ability than training at heavy loads and the changes in kinetic and kinematic outputs were not usefully related to changes in sprint ability.

The use of the squat exercise (and its derivatives) in gym-based settings is widespread owing to perceived functional performance enhancing effects. In particular, there has been preponderance amongst practitioners with loads that maximise power outputs (Pmax) based on a perception that mechanical peak power is directly related to explosive functional performance such as sprinting ability. The optimal muscular quality associated with squats remains elusive though, mostly due to methodological limitations in the research. The four experimental studies in this thesis sought to quantify the kinetic and kinematic outputs of a machine squat-jump and their relationship to sprinting ability, both descriptively and across a training period. First, an analysis of the kinetic and kinematic outputs of a machine squat-jump across a spectrum of loads was performed, with an emphasis on power output. Then, the relationship of these outputs with sprint ability was investigated. Correlations do not imply cause and effect, thus a training intervention was undertaken to quantify the relationships of the change in performance measures over time, and allow a comparison of different training protocols. Specifically, one training group was prescribed training loads based on individually determined peak power outputs, and the other based on traditional maximal strength training loads. Because the intention of this thesis was to enhance our knowledge of best strength training practice for elite sporting performance, highly trained athletes were specifically chosen as subjects, cognizant of the population specific nature of training adaptation. In study one, it was determined that the point on the power-load spectrum where peak and mean power occurred in the machine squat-jump was 21.6 ± 7.1 %1RM (mean ± SD) and 39.0 ± 8.6 %1RM respectively although there was considerable individual variation in these points. A broad plateau in power outputs was evident for most subjects with at most a 9.9% (90% confidence limits ±2.4%) difference in peak or means power at loads up to 20 %1RM either side of the peak. Studies two and three established that, of the multiple kinetic and kinematic measures investigated, only 1RM strength, work and impulse (all relative to body mass) provided any indication of useful kinetic / kinematic outputs that were potentially worthwhile developing for enhancing sprint performance, albeit with only moderate correlations (r = ~ -0.3). Additionally, the intercorrelations between maximal strength and explosive kinetic and kinematic measures were only moderate (r = ~0.3), casting doubt on the common practice of pursuing high 1RM strength with the intention of improving explosive muscle performance. The training study provided evidence that training at the load that maximised individual peak power output was no more effective for improving sprint ability than training at heavy loads and the changes in kinetic and kinematic outputs were not usefully related to changes in sprint ability.

The diploma thesis is focused on the issues of handling heavy loads using a crane. The thesis tries to identify threats in the process. Analysis of the current state evaluates the issue from the perspective of OHS not only in the Czech Republic but also in selected states of the European Union. Furthermore, the analysis discusses the obligations of employees and employers in the field of safety and clarifies the basic concepts of the issue. Based on a model example, the analyzes are performed to that identify the threats with the highest level of risk Subsequently, there are presented measures which should lead to the minimization of the level of risk for identified process threats.