Efeitos da fadiga mental na função física de indivíduos idosos

Abstract

In the present thesis we conducted two studies. The first one mapped out the existing studies interested to investigate the effects of mental fatigue and physical function of older people, assessing its quantity, quality, methods, physical functions evaluated and the main results. The second study investigated the influence of mental fatigue on older people’s enjoyment during the walking and balance tests, and the resistance exercise. In study 1, we conducted a systematic scoping review of literature involving older people using the PubMed/MEDLINE, Scopus, Web of Science – Core Collection. The scoping review comprehensively tracked the current state of studies on mental fatigue and physical function of older people through the categorisation of studies by features, a tabular summary of studies characteristics, and risk of bias analysis. 15 studies (1 abstract and 14 full-texts) met the inclusion criteria and were subject to analysis in this scoping review. Results indicated that publications on the effects of mental fatigue in the elderly population are relatively new; therefore, scarce. The most common combined method to induce mental fatigue was mental maths and quiet sitting; but when analysing experimental and control conditions separately, the most common methods were laboratory-based tasks for induction with low ecological validity and the use of a movie, documentary or reading as control. The review also suggested the lack of true experimental research in the field. The present review highlighted that most studies were interested in understanding the differences in mental fatigue effects between age groups; most studies included only healthy participants and that; overall, elderly people display greater force fluctuations than their young peers in contexts of cognitive demand. 35 participants were included in the study 2. Using a randomised cross-over design, participants completed a series of physical tests (i.e., 6 min walk test, and balance task), and a brief standardised resistance exercise after two experimental conditions (control or mental fatigue). The Nonparametric Analysis of Longitudinal Data in Factorial Experiments was used to compare the difference in the number of repetitions performed during the three sets of resistance exercise between the control and mental fatigue conditions. The same test was used to compare the RPE and Enjoyment in the 5 moments (Post-6MWT, Post-TUG, Post-KE1, Post-KE2, Post-KE3) and 2 conditions (mental fatigue x control) and the VAS scales in the 4 moments (baseline, Pre-6MWT, Pre-TUG, Pre-KE) and 2 conditions (mental fatigue x control). Mental fatigue had no effect on the physical function, perception of effort and enjoyment to exercise of older people. Participants, however, presented a higher affinity, characterized by higher enjoyment, for walking and dynamic balance compared to strength exercise. However, due to the relevance of resistance exercises for health, clinicians and gyms should allocate resources to education programs regarding the importance of resistance exercise for health in the short and long-term, include social interaction opportunities in the physical exercise programs and, prescribe appropriate activities to participants’ ability level. In conclusion, the present thesis suggests that is not clear whether the state of mental fatigue is really an issue for healthy older people, and that it might be beneficial to walk two steps back, and conduct qualitative and mixed-methods studies to understand whether mental fatigue as a state is a condition that affects healthy older people.