Sprint kayaking is prominent in Europe with training methods devised and adopted from Eastern bloc training systems. There is a lack of published research on sprint kayaking locally and internationally. Consequently, the aims of this research directly address establishing a relationship between kayak specific training and the Profile of Mood States (POMS); monitoring training duration and intensity and establish a link with the POMS and Rating of Perceived Exertion (RPE); to monitor the general wellness of the kayakers. Seven elite sprint kayakers (two male, five female) with the following characteristics: age 26.5 (1.4) years, training experience 8.4 (3.7) years were part of the South African national sprint kayaking squad selected to participate in this study, based on their preparation for the 2008 Beijing Olympic Games (one male athlete did not qualify but continued to train). The females trained for the 500m K1, K2 and K4 events and the male for the 1000m K1. Three training camps (TC1, TC2, TC3) were held from 12 November to 09 December 2007, 25 February to 22 March 2008 and 14 July to 04 August 2008. RPE (Borg Scale) was recorded for each session. The 65-item POMS was completed twice a week, after half a days rest (Wednesday) and after a day and half rest (Sunday). Daily training load was calculated from RPE and session time; and an energy index calculated from the POMS vigour and fatigue scores. The Wisconsin Upper Respiratory Symptom Survey recorded illness and injury. Descriptive and Inferential Statistics, Friedman’s rank test for k correlated samples, The Wilcoxon Signed Ranks Test, Spearman rank-order correlations were used to analyse the data. Statistical significance was calculated at 5% (p=0.05) and 10% (p=0.1). The results showed higher vigour scores associated with lower RPE and low training load; and high RPE associated with higher anger, confusion, depression, fatigue and total mood disturbance scores. There was a relationship between increasing POMS scores and duration of the training camps. The POMS findings could not completely explain the relationship found between RPE and duration of the training camps. The energy index was higher pre-camp and the extended rest periods during the camps. The findings for the POMS and RPE suggested that a state of overreaching might have occurred during the camps. Monitoring of the kayakers for an extended period after the training camps would have been useful to determine whether any of these individuals became over-trained. In accordance with Kentta et al (2006), regular use of the POMS may help detect under recovery, preventing staleness and unwanted rest for extended periods. Future studies will enable a retrospective view on these results. / Dissertation (MA)--University of Pretoria, 2012. / Biokinetics, Sport and Leisure Sciences / unrestricted

The cyclin-dependent kinase (Cdk) inhibitor p27Kip1 contributes to the timing of cell cycle withdrawal during development and, consequently, in organogenesis. Within the retina, this effector protein is up-regulated during the birth of neuronal and glial cells [Dev. Biol. (2000) 299]. However, its expression within the retinal pigment epithelium (RPE), a supporting cell layer that is essential for neural retina development and function, has not previously been reported. We show that p27Kip1 protein expression in the RPE occurs in two phases: an up-regulation during mid-to late embryonic stages and a down-regulation during the subsequent postnatal period. In the early phase of up-regulation, an inverse relationship is seen between expression of p27Kip1 and PCNA, an indicator of cycling cells. During both up-and down-regulation, the change in spatial pattern of expression proceeds in a central to peripheral manner, with p27Kip1 up-regulation paralleling retinal maturation. These data suggest that this cell cycle regulator may be an important factor controlling the timing of RPE cell cycle withdrawal.

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This study is a subset of a larger body of research that examined shoulder time to fatigue during overhead work in an attempt to reduce the prevalence and impact of work-related musculoskeletal problems in the shoulder associated with overhead work, particularly during automobile assembly. Existing evidence suggests that shoulder injuries are diverse in terms of tissues affected and symptoms presented. Furthermore, the cause of these injuries is multifactorial. The work presented here assumes that musculoskeletal injuries of the shoulder mechanism are at least related to, if not caused by, fatigue localized to the shoulder musculature. While the exact relationship between fatigue and injury has not been clearly established, there is consensus among researchers that fatigue plays and important role. Muscular fatigue, therefore, is viewed as a surrogate measure of risk, and task design to avoid fatigue is seen as a rational method to minimize this risk. An experiment to determine the effects of tool weight on shoulder fatigue and performance during overhead work with work/rest cycles was performed. Times to fatigue were derived based on dependent measures including total task duration, controlled maximum muscle contractions, subjective ratings based on Borg's CR-10 RPE scale, electromyogram behavior (MdPF), and hand force performance measures. Experimental findings indicated that duty cycle (percentage of total task cycle time spent working) significantly affected task duration (p<0.0001), changes in maximum voluntary contraction values for the infraspinatus (p<0.05), and the minimum time for any shoulder muscle to fatigue as determined by changes in the EMG power spectrum (p<0.05). Time to fatigue for the mid deltoid as determined by changes in the median frequency of the EMG power spectrum was shown to change significantly (p<0.05) with change in tool weight. Large intersubject variation was observed for the dependent measures, which showed subjects experiencing different levels of fatigue while performing the same task. Limitations of the study and recommendations for future direction are also discussed. / Master of Science

Repetitive and forceful exertions have been dentified as an important risk factor for occupational injuries. One method used to determine appropriate exposures to these and other risk factors is psychophysics, which is based on individual perceptions of task demands and/or risk. Effects of work exposure have been indicated as of potential importance, but have not been well studied. Indications from an earlier study related to psychophysical limits for a repetitive manual torquing task were that five days of work conditioning had minimal effects on resulting Maximum Acceptable Repetition Rates (MARR). However, it is unknown whether and how longer work exposure durations might influence MARRs. The current study investigated the effects of work exposure on MARR and adjustment time over 10 working days (two weeks) with two days of rest after five days. Ten participants (five males and five females) performed a manual torquing (45 Nm load) task at mid-chest level in the coronal plane for a one hour test session. Starting repetition rate for each participant was set at single high and low rate on alternate days. Temporal (exposure) effects were determined, where day of exposure was the independent variable, and MARR and adjustment time were the dependent variables. Final MARRs were relatively lower during the first few exposure days (14 - 15 repetitions/min) and increased for days 5 - 7 (16 - 18 repetitions/min). On average participants made four adjustments to reach MARR . Day was not found to significantly affect MARR, though week affected both MARR and adjustment time. Thus, an exposure of two weeks may be needed to obtain stable and valid psychophysical limits for manual torquing and, perhaps, related tasks. / Master of Science