Mathematical model of COVID-19 intervention scenarios for São Paulo-Brazil.

With COVID-19 surging across the world, understanding the effectiveness of intervention strategies on transmission dynamics is of primary global health importance. Here, we develop and analyze an epidemiological compartmental model using multi-objective genetic algorithm design optimization to compare scenarios related to strategy type, the extent of social distancing, time window, and personal protection levels on the transmission dynamics of COVID-19 in São Paulo, Brazil. The results indicate that the optimal strategy for São Paulo is to reduce social distancing over time with a stepping-down reduction in the magnitude of social distancing every 80-days. Our results also indicate that the ability to reduce social distancing depends on a 5-10% increase in the current percentage of people strictly following protective guidelines, highlighting the importance of protective behavior in controlling the pandemic. Our framework can be extended to model transmission dynamics for other countries, regions, states, cities, and organizations.

Mixed Modal Training to Help Older Adults Maintain Postural Balance.

OBJECTIVE: Older adults have poorer balance compared with younger adults, but exercise may slow this age-related loss. Although the best type of exercise to optimize balance gains remains unclear, it is likely that a training regimen incorporating several different types of exercise, termed mixed modality training (MMT) (popularized by CrossFit), would be effective. Accordingly, this study aims to assess whether regular MMT leads to improved balance in older adults. METHODS: Ten trained young (28 ± 4 years, minimum of 1 year MMT) and 22 older (67 ± 6 years) adults participated in this study. Older adults were divided into 2 groups: trained (minimum of 1 year MMT) and untrained. An electronic baropodometer was used to assess baseline postural balance using the postural sway (both open and closed eyes) test. RESULTS: Compared with untrained older adults, those who trained performed similarly to young trained adults in the postural sway test. In addition, with eyes closed, trained older adults demonstrated better center of pressure total displacement area than untrained older adults. CONCLUSION: These data suggest that regular MMT can lead to a level of postural control in older adults similar to that observed in young adults. The favorable effects of MMT on postural control in older adults may be attributable to improvements in both muscle strength and proprioception.

Age-associated differences in motor output variability and coordination during the simultaneous dorsiflexion of both feet.

Older adults are more variable than young adults on tasks that demand the simultaneous control of more than one effector, and the difference between age groups may be related to their different capacity of coordinating the force output of the involved effectors. The goal of this study was to determine whether age-associated differences in motor output variability during tasks involving the simultaneous dorsiflexion of two feet can be partially explained by differences in coordination and possibly attenuated by physical training. Ten young and 22 old adults (10 trained and 12 untrained old adults) volunteered to participate in the study. Trained older adults had experience in a high-intensity mixed modality training (MMT) regime for a minimum of 1 year. Volunteers performed successive trials of a constant force task and a goal-directed task, with and without visual feedback. Within- and between-trial variability were calculated and coordination was quantified using the uncontrolled manifold (UCM) approach (i.e., co-variation of the force outputs of both feet were used to quantify a motor synergy index). Older adults exhibited greater variability and lower synergy (p < .05), independently of physical training status, than young adults. Removal of visual feedback caused greater variability and lower synergy for all groups (p < .05). Our results suggest that older adults exhibit greater motor output variability in tasks involving the simultaneous dorsiflexion of both feet possibly due to a lack of coordination between the feet.