The concept of ‘Successful Aging’ has long intrigued the scientific community. Despite this long-standing interest, a consensus definition has proven to be a difficult task, due to the inherent challenge involved in defining such a complex, multi-dimensional phenomenon. The lack of a clear set of defining characteristics for the construct of successful aging has made comparison of findings across studies difficult and has limited advances in aging research. The domain in which consensus on markers of successful aging is furthest developed is the domain of physical functioning. For example, walking speed appears to be an excellent surrogate marker of overall health and predicts the maintenance of physical independence, a cornerstone of successful aging. The purpose of the present article is to provide an overview and discussion of specific health conditions, behavioral factors, and biological mechanisms that mark declining mobility and physical function and promising interventions to counter these effects. With life expectancy continuing to increase in the United States and developed countries throughout the world, there is an increasing public health focus on the maintenance of physical independence among all older adults.

BackgroundPhysical exercise is associated with decreased cardiovascular disease (CVD) risk, but recent large-scale trials suggest that exercise alone is insufficient to reduce CVD events in high-risk older adults.PurposeThis pilot randomized clinical trial aimed to collect critical data on feasibility, safety, and protocol integrity necessary to design a fully powered randomized controlled trial (RCT) and evaluate the impact of combining structured exercise with an intervention designed to enhance non-exercise physical activity (EX+NEPA) compared to EX alone.MethodsForty participants aged ≥60 years with moderate-to-high risk of coronary heart disease events were randomly assigned to either the EX+NEPA or EX groups and followed for 20 weeks. Both groups underwent a twice-weekly, 8-week center-based exercise intervention with aerobic and resistance exercises. EX+NEPA group also received a wearable activity tracking device along with behavioral monitoring and feedback throughout the study. Study outcomes were evaluated at 8 and 20 weeks.ResultsData are presented as adjusted mean change of the differences over time with 95% confidence intervals at 20 weeks. Relative to EX, the change in steps/day at 20 weeks was 1994 (−40.27, 4028) higher for EX+NEPA. For sedentary time at close-out, the EX+NEPA group was −6.8 (−45.2, 31.6) min/day relative to EX. The between-group differences for systolic and diastolic blood pressure were −9.9 (−19.6, −0.3) and −1.8 (−6.9, 3.3) mmHg, respectively.ConclusionThe addition of wearable technology intervention appeared to positively influence daily activity patterns and changes in blood pressure – potentially improving risk factors for CVD. A fully powered randomized trial is needed to ultimately test this hypothesis.

Repair of skeletal muscle after injury is a key aspect of maintaining proper musculoskeletal function. Studies have suggested that regenerative processes, including myogenesis and angiogenesis, are impaired during advanced age, but evidence from humans is limited. This study aimed to compare active muscle regeneration between healthy young and older adults. We evaluated changes in clinical, biochemical, and immunohistochemical indices of muscle regeneration at precisely 2 (T2) and 7 (T3) days following acute muscle injury. Men and women, aged 18-30 and ≥70 years, matched for gender and body mass index, performed 150 unilateral, eccentric contractions of the plantar flexors at 110% of one repetition maximum. Data were analyzed using analysis of covariance, adjusted for gender, habitual physical activity, and baseline level of the outcome. A total of 30 young (n = 15; 22.5 ± 3.7 yr) and older (n = 15; 75.8 ± 5.0 yr) adults completed the study. Following muscle injury, force production declined 16% and 14% in young and older adults, respectively, by T2 and in each group, returned to 93% of baseline strength by T3. Despite modest differences in the pattern of response, postinjury changes in intramuscular concentrations of myogenic growth factors and number of myonuclear (4',6-diamidino-2-phenylindole+ and paired box 7+) cells were largely similar between groups. Likewise, postinjury changes in serum and intramuscular indices of inflammation (e.g., TNF-α and monocyte chemoattractant protein-1) and angiogenesis (e.g., VEGF and kinase insert domain receptor) did not differ significantly between groups. These findings suggest that declines in physical activity and increased co-morbidity may contribute to age-related impairments in active muscle regeneration rather than aging per se.

BackgroundData are sparse regarding the value of physical activity (PA) surveillance among older adults—particularly among those with mobility limitations. The objective of this study was to examine longitudinal associations between objectively measured daily PA and the incidence of cardiovascular events among older adults in the LIFE (Lifestyle Interventions and Independence for Elders) study.Methods and ResultsCardiovascular events were adjudicated based on medical records review, and cardiovascular risk factors were controlled for in the analysis. Home‐based activity data were collected by hip‐worn accelerometers at baseline and at 6, 12, and 24 months postrandomization to either a physical activity or health education intervention. LIFE study participants (n=1590; age 78.9±5.2 [SD] years; 67.2% women) at baseline had an 11% lower incidence of experiencing a subsequent cardiovascular event per 500 steps taken per day based on activity data (hazard ratio, 0.89; 95% confidence interval, 0.84–0.96; P=0.001). At baseline, every 30 minutes spent performing activities ≥500 counts per minute (hazard ratio, 0.75; confidence interval, 0.65–0.89 [P=0.001]) were also associated with a lower incidence of cardiovascular events. Throughout follow‐up (6, 12, and 24 months), both the number of steps per day (per 500 steps; hazard ratio, 0.90, confidence interval, 0.85–0.96 [P=0.001]) and duration of activity ≥500 counts per minute (per 30 minutes; hazard ratio, 0.76; confidence interval, 0.63–0.90 [P=0.002]) were significantly associated with lower cardiovascular event rates.ConclusionsObjective measurements of physical activity via accelerometry were associated with cardiovascular events among older adults with limited mobility (summary score >10 on the Short Physical Performance Battery) both using baseline and longitudinal data.Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01072500.

Objective To evaluate the extent of variability in functional responses among participants in the LIFE study, and to identify the relative contributions of intervention adherence, physical activity, and demographic and health characteristics to this variability. Design Secondary analysis of the Lifestyle Interventions and Independence for Elders (LIFE) study. Setting Multicenter U.S. institutions participating in the LIFE study. Participants A volunteer sample of 1635 sedentary men and women aged 70 to 89 years who were able to walk 400 m, but had physical limitations, defined as a score on the Short Physical Performance Battery (SPPB) of ≤9. Interventions Moderate-intensity physical activity (PA, n=818) consisting of aerobic, resistance and flexibility exercises performed both center-based (twice/wk) and in or around the home environment (3-4 times/wk) or health education (HE, n=817) consisting of weekly to monthly workshops covering relevant health information. Main Outcome Measures Physical function: gait speed over 400-m and lower extremity function (SPPB) assessed at baseline, six, twelve, and 24 months. Results Greater baseline physical function (gait speed and SPPB score) was inversely associated with Δ gait speed (regression coefficient β=−0.185, p<0.001) and ΔSPPB score (β=−0.365, p<0.001), while greater number of steps per day measured by accelerometry was positively associated with Δ gait speed (β=0.035, p<0.001) and Δ SPPB score (β=0.525, p<0.001). Other baseline factors associated with positive Δ gait speed and/or SPPB score include younger age (p<0.001), lower body mass index (p<0.001), and higher self-reported physical activity (p=0.002). Conclusions Several demographic and physical activity-related factors were associated with the extent of Δ functional outcomes among participants in the LIFE study. These factors should be considered when designing interventions for improving physical function among older adults with limited mobility.