Doctoral Degrees (Exercise, Sport and Lifestyle Medicine)

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Browsing Doctoral Degrees (Exercise, Sport and Lifestyle Medicine) by Author "Coetsee, Carla"

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    The relation of exercise training mode, brain oxygenation and cognition in healthy older adults
    (Stellenbosch : Stellenbosch University, 2015-12) Coetsee, Carla; Terblanche, Elmarie; Stellenbosch University. Faculty of Education. Dept. of Sport Science.
    ENGLISH ABSTRACT: Background: Physical exercise has been shown to prevent cognitive decline and dementia in later life and is generally proposed as a non-pharmacological treatment to reverse or delay the age-related deteriorations in physical and cognitive health. However, it is unknown how different types of exercise will compare with regards to gains in older individuals’ physical and cognitive function and, in particular, the role of high-intensity interval training, has not been extended to the cognitive function literature. Aims: The purpose of this thesis was to determine the effects of three different exercise training modalities (resistance training, high-intensity interval training and moderate continuous training) on physical and cognitive function, as well as cerebral oxygenation. Methods: Sixty seven inactive individuals (55 to 75 years) volunteered for this intervention study. Participants were allocated to a resistance training (RT) group (n=22), high-intensity interval training (HIIT) group (n=13), moderate continuous training (MCT) group (n=13) and a control (CON) group (n=19). Each training group performed three supervised exercise sessions per week over a period of 16 weeks. Cognitive function was assessed every four weeks with a computerized Stroop task, while physical function was assessed with the Timed-Up-and-Go (TUG) and submaximal Bruce treadmill tests. Changes in cerebral oxygenation during the Stroop task were measured at baseline and after the 16-week intervention period. Furthermore, muscle strength was assessed in the CON and RT groups with 10RM leg and bench press tests. The RT and CON groups repeated their baseline measurements after a subsequent 16-week detraining (DET) period. Results: Upper and lower body strength generally improved significantly after every four weeks of RT (with an increase after 16 weeks of 7.3 ± 4.9 kg and 86.6 ± 44.4 kg, respectively; P < 0.001), while TUG performance (-0.2 ± 0.4 s; P < 0.05) and submaximal endurance capacity (0.7 ± 0.9 min; P < 0.001) only improved after 16 weeks. Although muscle strength decreased after detraining, it remained at a level higher than baseline (P < 0.05). Submaximal endurance capacity improved after DET (P < 0.001), while TUG performance returned to baseline. The HIIT group showed a greater improvement in TUG performance (-0.3 ± 0.4 s; ES = 0.36) and walking endurance (1.4 ± 1.3 min; ES = 0.91) compared to RT and MCT. Within each group only RT showed statistically significant improvements, with HIIT and MCT presenting the same trend, beyond the 4-week intervention period, on the measures of executive cognitive function (ES > 0.70). The brain oxygenation results revealed higher relative O2Hb values in CON during the simple and complex Stroop tasks at the post-test compared to the pre-test values (P < 0.05), as well as compared to all three exercise training groups (P < 0.05). Conclusion: Increases in muscular and physical function in older individuals were not induced in a concurrent manner over the course of a RT programme. Furthermore, older adults retained a significant amount of muscle strength and submaximal endurance capacity after a period of DET, while functional mobility was completely reversed. HIIT proved to be most beneficial for the enhancement of older individuals’ aerobic fitness. Exercise training proved more beneficial for the enhancement of executive cognitive function compared to no training. It was also demonstrated that exercise training, independent of the mode, results in more efficient cerebral oxygenation during cortical activation, whereas HIIT and MCT proved to be superior to RT for task-efficient cerebral oxygenation and improved oxygen utilization during cortical activation in older individuals.