ECSS Paris 2023: CP-MH01
INTRODUCTION: Physical inactivity increases the risk of dementia [1]. Previous studies have focused on total sedentary time, without accounting for how it accumulates throughout the day. Frequent sedentary breaks have been associated with improved glycemic and blood pressure control [2,3], both of which are recognized risk factors for dementia. In this study, we examined the association between frequency of sedentary breaks and cognitive function in Japanese community-dwelling older adults. METHODS: In this cross-sectional study, 952 community-dwelling older adults aged ≥65 years participated and wore a triaxial accelerometer for 10 consecutive days. Activity intensity was derived from accelerometer data. Sedentary behavior was defined as ≤1.5 METs, and sedentary breaks were identified as transitions from sedentary behavior to activity >1.5 METs. Participants were categorized into quartiles (Q1–Q4) according to the daily frequency of sedentary breaks. Cognitive performance was assessed using a battery of tests, including the Mini-Mental State Examination, the Logical Memory I and II subtests of the Wechsler Memory Scale–Revised, and the Trail Making Test A and B (TMT-A, TMT-B). Cognitive performance was compared across quartiles. RESULTS: In men, a higher frequency of sedentary breaks was significantly associated with better performance on TMT-A and TMT-B after adjustment for age, waking time, total sedentary time, and light-intensity physical activity (TMT-A: p for trend = 0.02; TMT-B: p for trend = 0.04). In women, a higher frequency of sedentary breaks was significantly associated with better performance on TMT-A (p < 0.01 for trend). CONCLUSION: A higher sedentary break frequency in daily life was associated with better TMT performance in community-dwelling older adults. These associations persisted even after adjusting for total sedentary time and light-intensity physical activity, suggesting that the frequency of sedentary breaks reflects a different aspect of sedentary behavior. These results suggest that the frequency of sedentary breaks may represent an important behavioral indicator of cognitive performance in older adults. Reference 1. Livingston G, et al., Lancet., 2024 2. Hartman SJ, et al., Circulation., 2025 3. Duran AT, et al., Med Sci Sports Exerc., 2023
Read CV Saki HashimotoECSS Paris 2023: CP-MH01
INTRODUCTION: Skeletal muscle satellite cells are essential in muscle fiber regeneration, repair, and growth. Aging is accompanied by specific loss of type II muscle fiber size and associated satellite cell content and function. Muscle fiber capillarization has been suggested to play a key role in satellite cell function. We assessed whether 8 weeks of aerobic exercise training, to increase muscle fiber capillarization, improves the acute type II muscle fiber satellite cell response to a single bout of resistance exercise in healthy older adults. METHODS: In a randomized parallel design, n=26 healthy older (70±5 y) adults participated in 8 weeks of aerobic exercise training (AER, n=14), 3 times per week for 45 min at 65% VO2peak or no-exercise control (CON, n=12). Aerobic capacity (VO2peak tests on cycling ergometer) and body composition (DXA-scan) were assessed at baseline and following 8 weeks of AER or CON intervention. Resting vastus lateralis muscle biopsies were collected at baseline and following the 8-week AER or CON intervention. To assess the acute satellite cell response, two additional biopsies were obtained at 24 and 48 h following a single bout of resistance exercise after the 8-week AER or CON intervention. Immunohistochemistry was used to assess type I and type II muscle fiber size, capillarization, and satellite cell content. Data were analyzed by two-way repeated-measures ANOVA. Post-hoc testing was performed in case of a significant time x treatment interaction effect. Statistical significance was set at P<0.05. All data are expressed as mean±SD. RESULTS: Aerobic exercise training increased VO2peak (9±6%, P<0.05), with no changes in leg lean mass. VO2peak and leg lean mass remained unchanged in response to the 8-week CON condition. Whereas type I muscle fiber size remained unchanged, a main effect of time (P<0.05) was observed for type II muscle fiber size, which was mainly driven by hypertrophy observed in the AER group (24±48%, P<0.05). Type I (33±25%, P<0.05) and type II (37±40%, P<0.05) muscle fiber capillarization increased in the AER group, with no changes in the CON group. Aerobic exercise training increased type I (97±65%, P<0.05), but not type II muscle fiber satellite cell content. Type I and II muscle fiber satellite cell content remained unchanged in the CON group. The acute type I and II muscle fiber satellite cell response was not different between the AER and CON group (interaction effects, P>0.1) at 24 and 48 h following the single bout of resistance exercise. CONCLUSION: Aerobic exercise training increases type I and II muscle fiber capillarization and satellite cell content in type I muscle fibers in healthy older adults. The type II muscle fiber satellite cell response to an acute bout of exercise is not modified by prolonged aerobic exercise training. An increase in muscle fiber capillarization does not improve post-exercise muscle satellite cell function in healthy older adults.
Read CV Milan BetzECSS Paris 2023: CP-MH01
INTRODUCTION: It remains unclear whether background physical activity modulates cardiorespiratory and metabolic adaptations to short-term high-intensity interval training (HIIT) in recreationally trained individuals. Therefore, the purpose of this study was to determine the effects of experimentally manipulating daily step counts on physiological adaptations to HIIT. METHODS: Twenty-four recreationally trained men (VO2max > 55 mL kg-1 min-1) completed five HIIT sessions over two weeks and were assigned to either low (~5,000 steps day-1) or high (~15,000 steps day-1) background physical activity. Pre- and post-intervention assessments included incremental treadmill testing, submaximal cardiorespiratory responses, ventilatory thresholds, resting metabolism, oral glucose tolerance, high-fat tolerance, postprandial substrate oxidation, and continuous glucose monitoring. Group x time effects were analyzed using linear mixed-effects models. RESULTS: Daily step counts differed as intended between groups (p < 0.001), while training intensity and adherence were comparable. VO2max increased in the high-step group (+4.4%, p < 0.01) but not in the low-step group (p > 0.99), resulting in a significant group x time interaction (p < 0.01). During submaximal exercise, the high-step group demonstrated reductions in oxygen uptake (−3.1%, p = 0.024), heart rate (−2.8%, p = 0.02), and blood lactate concentration (p = 0.01), alongside an increase in ventilatory threshold 1 (~12%, p < 0.01). No corresponding improvements were observed in the low-step group. Postprandially, the high-step group exhibited a higher respiratory exchange ratio (p = 0.037) alongside a tendency toward greater carbohydrate oxidation. No group x time interactions were observed for glucose or triglyceride tolerance (all p > 0.25). CONCLUSION: Higher background physical activity augments cardiorespiratory and submaximal efficiency adaptations to short-term HIIT in recreationally trained men, whereas low daily activity constrains training responsiveness despite matched exercise exposure. From a practical perspective, training interventions should monitor habitual physical activity in parallel with structured training load, as both contribute jointly to the adaptive outcome.
Read CV Mascha LenkECSS Paris 2023: CP-MH01