Cross-sectional interactive associations of physical activity and sedentary behaviour with physical capacity across adulthood.

BACKGROUND: The way physical activity (PA) and sedentary behaviour (SB) independently and interactively modify the age-related decline in physical capacity remains poorly understood. This cross-sectional study investigated the independent and interactive associations of PA and SB with physical function and performance throughout the adult life course. METHODS: Data from 499 community-dwelling adults (63% female) aged 20-92 years, involved in the INSPIRE Human Translational Cohort, were used in this cross-sectional study. Daily time spent on moderate-to-vigorous PA (MVPA, min/day) and SB (h/day) was measured with activPAL triaxial accelerometers. Physical function and performance were assessed through the measurement of the 4-m usual gait speed (m/s), handgrip strength (kg), lower-limb strength (isokinetic knee extension torque, N·m), estimated lower-limb power (five-time chair-rise test performance, s) and cardiorespiratory fitness (V̇O2max, mL/kg/min). Confounder-adjusted multiple linear and curvilinear regressions were performed to investigate how MVPA, SB and their interactions were associated with the physical outcomes (all square root-transformed except gait speed) throughout the adulthood spectrum. RESULTS: Interaction analyses revealed that the combination of higher levels of MVPA with lower levels of SB favourably reshaped the negative relationship between handgrip strength and age (age2 × SB × MVPA: B = -7E-08, SE = 3E-08, P < 0.05). In addition, higher levels of MVPA were independently associated with an improved age-related profile in gait speed (age2 × MVPA: B = 3E-06, SE = 1E-06, P < 0.05), chair-rise performance (age × MVPA: B = -9E-05, SE = 4E-05, P < 0.05) and V̇O2max (MVPA at 21 years: B = 3E-02, SE = 7E-03, P < 0.05; age × MVPA: B = -5E-04, SE = 2E-04, P < 0.05). Conversely, the detrimental association of age with lower-limb muscle strength (age × SB: B = -1E-04, SE = 6E-05, P < 0.05) and chair-rise performance (age × SB: B = 1E-05, SE = 7E-06, P < 0.05) was exacerbated with increasing duration of SB, independently of MVPA. Supplementary analyses further revealed that some of these associations were age and sex specific. CONCLUSIONS: This cross-sectional study demonstrated that reduced sedentary time and increased activity duration were independently and synergistically associated with an attenuated age-related loss in physical capacity. These findings need to be confirmed with longitudinal data but encourage both adopting an active lifestyle and reducing sedentary time as preventive measures against physical aging.

Psychosocial mediators and moderators of a school-based physical activity intervention among Brazilian adolescents.

School-based interventions are needed due to the low levels of physical activity (PA) in adolescents. The aim is to examine the mediation effects of psychosocial factors (attitude, self-efficacy, social support from parents, friends, general teachers, and PE teachers, and environment school perception) and moderation by sex, school grade, and socioeconomic level of a school-based PA intervention on the PA practice among adolescents. The Movimente Programme is a randomised controlled trial at schools in southern Brazil (n = 921 adolescents). Strategies included teacher training, educational actions, and environmental changes. Adolescents self-reported their weekly PA. Potential psychosocial mediators and moderators were investigated through validated questionnaires in a Brazilian sample. The product of the coefficients with percentile bootstrapping 95% confidence interval was performed. The Movimente Programme was related to positive changes in adolescents' perception of the school environment and social support from general and physical education teachers. Most psychosocial variables (attitude, self-efficacy, social support from friends, and social support from teachers) were associated with PA, but none mediated the impact of the Movimente Programme on PA. Results varied according to sex and school grade. The Movimente Programme increased the adolescents' perception of the school environment and social support from teachers, but no mediators were confirmed.

Mitochondrial Dysfunction and Intrinsic Capacity: Insights From a Narrative Review.

Mitochondrial dysfunction occurs during aging and may play a role, by distinct mechanisms, in the loss of intrinsic capacity (IC), operationalized through 5 domains: locomotion, psychological, cognition, vitality/nutrition, and sensory (hearing, vision). The objective of this review is to provide an overview of the associations between mitochondrial function and IC domains. This study is a narrative review of original investigations (any study design) on the relationship of mitochondrial function in humans with locomotion (eg, gait speed), psychological (eg, depressive symptoms), cognition (eg, global cognitive function), vitality (eg, handgrip strength), and/or sensory (hearing and vision acuity) domains. The IC domains were considered from the perspective of the Integrated Care for Older People (ICOPE), according to the World Health Organization guidelines. The results show that there is still limited evidence regarding the associations between mitochondrial function and IC domains. Most studies were cross-sectional and involved small samples. The tissues/cells most often investigated in the original studies were skeletal muscle and peripheral blood mononuclear cells. The available evidence, although limited, indicates that mitochondrial function, in particular, the mitochondrial DNA copy number, is associated with all IC domains. The evidence is more robust for locomotion and less abundant for hearing. In conclusion, this review supports the notion that mitochondrial function is correlated with IC domains by distinct mechanisms. Future studies are needed to confirm whether mitochondria play a role in maintaining optimal function and preventing/delaying the onset of disability during aging, which could ultimately contribute to healthy aging.