Discussion
The purpose of the present study was to determine the effect of an aerobic exercise and vitamin D supplements on the quality of sleep and neurocognitive functions of elderly women. The main finding was that the three neurocognitive factors in the experimental groups were better than the control group and the ATDG showed the better improvements compared to ATG and VDG. That is, both factors of nutrition and physical activity have had a double effect on the neurocognitive status of elderly women. The obtained results are consisitent with a previous study that pointed out that therapeutic supplementation can fascilitate the response time and information processing (18). Contrary to the results of the present study, Antypa et al. (2009) showed that the use of supplements in the main foods had no significant effect on the change in performance and the tasks that require decision making (19)(7). Differences in age groups (elderly versus youth), supplementation modes, and different research designs are of reasons in obtaining the divergent results. As indicated, the neurocognitive performance of elderly people improved significantly after aerobic exercises. For information processing, it was shown that the experimental groups were in a better condition than the control group. On the other hand, the selective attention of experimental groups were also better compared to control group. It should be noted that selective attention plays an important role in motor control of the elderly (20). In this regard, the results of the present study concerned the effectiveness of exercises on psychomotor function is consisitent with the results of the research of Monleon et al. (2018) who reported that appropriate exercise protocols lead to optimal psychomotor functions. Along with the current study, some studies have suggested that any type of exercise program that has decision-making challenges can lead to improved neurocognitive behavior in the elderly (18, 20). An explanation of these findings might be that changes and adaptations of the musculoskeletal system caused by functional exercises improve neurocognitive function. Possible reasons for this result include the use of more effective neural units, reorganization in the sensory cortex, increased efficacy of synaptic connections and activation of the nervous system, and reducing neural inhibitory reflexes (21). It has to be acknowledged that vitamin D deficiency is cross-sectionally associated with neurocognitive disfunctions, particularly mental shifting, information processing, and processing speed (8, 9). Furthermore, when results have been combined across trials, meta-analytic studies have consistently reported cognitive benefits from aerobic exercise interventions (10, 11).
There are some limitations in the present study. This research may have been underpowered due to a relatively smaller sample size. It is also possible to study both sexes together. To study each sex separately would remove sex as a confounding factor. Further studies that include subjects in both acute and chronic effects of vitamin D and exercise protocols are needed.
In conclusion, aerobic exercises plus vitamin D supplements improve the neurocognitive functioning of elderly women. As this condition improves as a result of increasing the quality of life of the elderly, it is recommended that vitamin D supplementation and aerobic exercise be used in conjunction with older women.