Patterns of sedentary behavior : insights from observational and experimental studies on body composition and energy expenditure

It is recognized that sedentary behavior (SB) has deleterious effects on numerous health outcomes and it appears that physiological mechanisms underlying these harms are distinct from the ones explaining moderate-to-vigorous physical activity (MVPA) benefits. Sedentary behavior represents a large portion of human’s life and is increasing with technological development. A new current of opinion supports the idea that the manner SB is accumulated plays an important role. This dissertation presents six research studies conducted under the scope of SB. In the methodological area, the first study highlighted the magnitude of potential errors in estimating SB and its patterns from common alternative methods (accelerometer and heart rate monitor) compared to ActivPAL. This study presented the accelerometer as a valid method at a group level. Two studies (2 and 5) were performed in older adults (the most sedentary group in the population) to test the associations for SB patterns with abdominal obesity using accelerometry. The findings showed positive graded associations for prolonged sedentary bouts with abdominal obesity and showed that those who interrupted SB more frequently were less likely to present abdominal obesity. Therefore, public health recommendations regarding breaking up SB more often are expected to be relevant. The associations between sedentary patterns and abdominal obesity were independent of MVPA in older adults. However, the low MVPA in this group makes it unclear whether this independent relationship still exists if highly active persons are analysed. Study 3 inovates by examining the association of SB with body fatness in highly trained athletes and found SB to predict total fat mass and trunk fat mass, independently of age and weekly training time. Study 4 also brings novelty to this research field by quantifying the metabolic and energetic cost of the transition from sitting to standing and then sitting back down (a break), informing about the modest energetic costs (0.32 kcal·min−1). Finally, from a successful multicomponent pilot intervention to reduce and break up SB (study 6), an important behavioral resistance to make more sit/stand transitions despite successfully reducing sitting time (~ 1.85 hours·day-1) was found, which may be relevant to inform future behavioral modification programs. The present work provides observational and experimental evidence on the relation for SB patterns with body composition outcomes and energy regulation that may be relevant for public health interventions.

Observational research on golf-related injuries

The determination of aetiological factors in sports injuries is challenging. Recently, investigators have devoted significant attention to this topic. A reasonable amount of studies provides information on the occurrence, aetiology, and severity of golf-related injuries. However, gaps of evidence still limit the understanding of the injury problem in golf and the comparability of epidemiological findings. Observational studies using surveys and medical records were reviewed. Surveys are suited to find precise occurrence patterns of golf-related injuries, but fail to adequately ascertain the levels of exposure and aetiological factors. Due to the proximity to the injury event, medical records are able to clearly identify the aetiology and severity of golf-related injuries. While reviewing observational studies using surveys a comment was provided on the methodological quality and risk of bias. Overall, these studies seem to be disturbed on their ability to produce generalizations and comparison of study findings. With the information obtained from reviewing observational studies and the collaboration of a panel of internationally recognised experts on golf science and sports injury research, a web-based bilingual questionnaire was developed and tested for one of the provided languages. The bilingual nature of the questionnaire is also expected to facilitate the acceptance of the scientific community and enable the translation to different languages. A standardised questionnaire applied in different cultural contexts is expected to help and further improve the comparability of epidemiological findings. The questionnaire was proficient in capturing information on golf-related injuries and participation habits of golfers. While using a wider outcome definition focusing on any type of physical complaints, episodes of injury could be recognized despite onset and level of severity. Questions on the need for medical attention, time loss, and impact on performance also enabled additional categorisation of severity.