Age-related differences in the neuromuscular performance of fatigue-provoking exercise under severe whole-body hyperthermia conditions.

PURPOSE: The purpose of this study was to determine if aging would lead to greater decline in neuromuscular function during a fatiguing task under severe whole-body hyperthermia conditions. METHODS: Twelve young (aged 19-21 years) and 11 older (aged 65-80 years) males were enrolled in the study, which comprised a randomized control trial under a thermoneutral condition at an ambient temperature of 23°C (CON) and an experimental trial with passive lower body heating in 43°C water (HWI-43°C). Changes in neuromuscular function and fatigability, and physical performance-influencing factors such as psychological, thermoregulatory, neuroendocrine, and immune responses to whole-body hyperthermia were measured. RESULTS: A slower increase in rectal temperature, and a lower heart rate, thermal sensation, and sweating rate were observed in older males than young males in response to HWI-43°C trial (p < 0.05). Nevertheless, prolactin increased more in response to hyperthermia in young males, while interleukin-6 and cortisol levels increased more in older males (p < 0.05). Peripheral dopamine levels decreased in older males and increased in young males in response to hyperthermia (p < 0.05). Surprisingly, older males demonstrated greater neuromuscular fatigability resistance and faster maximal voluntary contraction (MVC) torque recovery after a 2-min sustained isometric MVC task under thermoneutral and severe hyperthermic conditions (p < 0.05). CONCLUSION: Neuromuscular performance during fatigue-provoking sustained isometric exercise under severe whole-body hyperthermia conditions appears to decline in both age groups, but a lower relative decline in torque production for older males may relate to lower psychological and thermophysiological strain along with a diminished dopamine response and prolactin release.

Tai chi effects on balance in older adults: the role of sustained attention and myokines.

BACKGROUND: Though previous research has shown that tai chi improves balance and reduces falls risk in older adults, the mechanisms responsible for this improvement remains not fully investigated. Thus, the aim of this study was to determine the efficacy of tai chi practice in improving weight loss, cognitive processes and molecular mechanisms underlying balance control in older adults. METHODS: Subjects aged 60-79 years were randomized to either a control group (N.= 15) or a tai chi group (N.= 15) for a 10-week period during COVID-19 pandemic. Changes in anthropometric characteristics, sustained attention, balance, myokines levels were assessed. RESULTS: Weight increased in control group (P<0.05), whereas it remained unchanged in tai chi group. Tai chi improved (P<0.05) accuracy during go/no-go task, center of pressure velocity in the Romberg stance position with eyes closed under single and dual-task conditions, and increased (P<0.05) levels of brain-derived neurotrophic factor and irisin, while in control group center of pressure velocity with eyes open tended to decrease. Changes in balance within 10 weeks were moderately correlated (P<0.05) with changes in anthropometric characteristics, sustained attention and levels of myokines. CONCLUSIONS: Thus, 10 weeks of tai chi practice induced improvements in balance, which was related with improved sustained attention, and increased myokines levels, whereas decrements in balance under pandemic conditions were related with weight gain in older adults.

Tai chi improves psychoemotional state, cognition, and motor learning in older adults during the COVID-19 pandemic.

The aim of this study was to determine the effect of a 10-week tai chi intervention on psychoemotional state, cognition, and motor learning in older adults during the COVID-19 pandemic. Participants aged 60-78 years were randomized to either a control group (n = 15) or a tai chi group (n = 15) for a 10-week period. The tai chi group received two, 8-form tai chi classes of 60 min duration per week. Changes in psychoemotional state, cognition, and the learning of fast and accurate reaching movements were assessed. In addition, the potential roles of the autonomic nervous system and brain-derived neurotrophic factor (BDNF) were investigated. Tai chi practice decreased (P < 0.05) perceived stress, whereas no change in autonomic nervous system activity was observed. Improvements in mental switching correlated with decreased depressive symptoms and increased BDNF levels (P < 0.05), whereas improvements in inhibitory control tended to correlate with BDNF levels (P = 0.08). Improvements in visuospatial processing tended to correlate with decreased depressive symptoms (P = 0.07) while improved visuospatial processing correlated with improved motor planning during learning tasks (P < 0.05). This study suggests that tai chi is an effective intervention that can be delivered under pandemic conditions to improve mental and physical function in older adults.

A 10-week yoga practice has no effect on cognition, but improves balance and motor learning by attenuating brain-derived neurotrophic factor levels in older adults.

Despite studies investigating the effect of yoga on cognitive and motor functioning in older adults, the effect on dual-task performance and motor learning and the specific mechanisms underlying the positive effect of yoga remain unclear. Thus, the aim of this study was to investigate the effects of yoga on cognition, balance under single- and dual-task conditions, and motor learning. The potential role of brain-derived neurotrophic factor (BDNF) in induced improvement was also explored. Participants aged 60-79 years were randomized to either a control group (n = 15) or a yoga group (n = 18) for a 10-week period. The yoga group received 90-min duration yoga classes two times per week. Changes in cognition, balance under single- and dual-task conditions, and learning fast and accurate reaching movements were assessed. Yoga practice decreased (P < 0.05) the velocity vector of the center of pressure under single- and dual-task conditions, whereas no changes in cognitive performance were observed. Although reaction and movement times during learning were decreased in both groups (P < 0.05), a faster reaction time (P < 0.05) and shorter movement time (P < 0.05) were observed in the yoga group than in the control group. Significant moderate relationships (P < 0.05) between changes in BDNF levels and functional improvements were observed. Thus, 10 weeks of yoga practice resulted in improved balance and learning in the speed-accuracy motor task that were mediated by increased BDNF levels, but had no impact on cognition in older adults.