Relationship between physical activity and intramyocellular lipid content is different between young and older adults

PURPOSE: Over 50% of adults do not engage in regular physical activity (PA). Genetic factors account for 32-85% of the variation in PA levels, but evidence identifying specific gene variants that influence habitual PA levels is limited. Thus, we examined associations among three genetic variants of the eNOS gene (-786T>C, rs2070744; -922A>G, rs1800779; 894G>T, rs1799983) and PA among healthy, young Caucasian adults. METHODS: Subjects (n=577, age 24.3±8.0yr, body mass index (BMI) 24.3±4.5kg·m-2) were genotyped for eNOS-786 T>C (n=308, TT n=128, TC n=147, CC n=33), -922 A>G (n=368, AA n=145, AG n=183, GG n=42), and 894 G>T (n=393, GG n=195, GT n=165, TT n=33). Subjects completed the Paffenbarger PA Questionnaire. PA phenotypes included; hr/wk spent in light, moderate and vigorous intensity PA, and sitting. Repeated measures ANCOVA tested associations among genetic variants and PA phenotypes by gender with age and BMI as covariates. Associations did not differ by gender so data are presented for the total sample. RESULTS: Adults with the eNOS 894 TT genotype reported less time in vigorous intensity PA than those with the GT and GG genotypes (4.3±1.3, 7.6±0.6, and 8.0±0.6hr/wk, respectively) (p=0.037). Adults with eNOS 894 TT genotype also reported spending more time in light intensity PA than adults with GT and GG genotypes (43.3±2.7, 36.4±1.2, and 34.5±1.1hr/wk, respectively) (p=0.009). In addition, those with eNOS 894 GT and GG genotypes reported to sit more than adults with the TT genotype (48.2±1.4, 45.9±1.3, and 38.3±3.2hr/wk, respectively) (p=0.014). CONCLUSIONS: Adults with the eNOS 894 TT genotype reported more time in light intensity PA, less time in vigorous intensity PA, and less time sitting than carriers of G allele. The vascular effects of regular episodic shear stress differs by PA intensity and may account for these eNOS 894 T>G genotype associations. However, our findings should be replicated in a prospective study designed to investigate the direct impact of PA on vascular function to determine if these suppositions are true. Supported by NIH-NINDS R01 NS40606-02 and the University of Connecticut. Center for Health, Intervention and Prevention.

The magnitude and direction of the association between sedentary time, physical activity (PA) of various intensities and weight status remain unclear. PURPOSE:The purpose of this study was to examine the cross-sectional and longitudinal effects of replacing sedentary time with light PA, moderate PA or vigorous PA on BMI in a large representative sample of adults and older adults. METHODS: We conducted cross-sectional (n=5013) and longitudinal (n=1823) analyses in a prospective cohort study in which PA was measured objectively by accelerometry (ActiGraph GT1M and GT3X+) for 7 days at both baseline (year 2008/09) and after 5 years. Exposure variables were daily time spent sedentary (below 100 cpm), and daily minutes spent performing light (100-2019 cpm), moderate (2020-5999 cpm) and vigorous intensity PA (6000 cpm and up). Outcome variable was BMI (kg/m2) derived from self-reported height and weight. Isotemporal substitution modelling was performed to convey the effects of replacing sedentary time with active behaviours on participant`s BMI. RESULTS: The isotemporal substitution models showed that replacing 10 minutes/day of sedentary time with an equal amount of time of either moderate PA (B=-0.2 95% CI: -0.2 to -0.1) or vigorous intensity PA (B=-1.0; 95% CI: -1.2 to -0.7) were associated with estimated beneficial effects on BMI after adjustments for age and socio-economic status in both genders. For men, replacing sedentary time with light intensity PA also showed small but significant beneficial associations with BMI (B=-0.1; 95% CI: -0.17 to -0.03). There were no longitudinal associations when replacing sedentary time with any of the PA intensities, after adjusting for baseline BMI. CONCLUSIONS: Replacing sedentary time with active behaviours is associated with BMI in cross-sectional but not prospective analyses. This may suggest that substituting sedentary time with PA at one point in time may not predict gain in BMI over time.

Physical activity has been linked to higher cardiac autonomic modulation. However, it is not clear in the literature which type of intensity of physical activity (sedentary, light, moderate, or vigorous) could be related to better cardiac autonomic modulation and whether this relationship is similar in men and women. The aim of this study was to analyze the relationship between cardiac autonomic modulation and the different intensities of physical activity in men and women. The sample included 100 men and 131 women. Cardiac autonomic modulation was obtained by heart rate variability (SDNN, RMSSD, LF un, HF un, SD1, and SD2). Time spent in different intensities (sedentary, light, moderate, and vigorous intensity physical activity) was measured using a waist-worn accelerometer for seven days. Linear regression was used to verify the relationship between physical activity and cardiac autonomic modulation, considering the adjustment for age, ethnicity, and socioeconomic level. Among men, a significant relationship of moderate intensity was observed with SDNN (β = 2.442; p = 0.021) and SD2 (β = 2.936, p = 0.028), and of vigorous intensity with SDNN (β = 12.826, p = 0.028), RMSSD (β = 16.370, p = 0.018), and SD1 (β = 12.344, p = 0.025) indices. Among women, light-intensity physical activity was significantly related with LFnu (β = .655, p = 0.005) and HFnu (β = -.590, p = 0.010). Moderate and vigorous physical activity was associated with better cardiac autonomic modulation in men. Light physical activity was associated with lower sympathetic modulation in women.

Existing knowledge on associations of physical activity (PA) and sedentary behavior (SB) with body composition and physical fitness in preschoolers is limited. To examine associations of PA and SB with body composition and physical fitness in healthy Swedish 4-year-old children. We utilized baseline data collected in 2014 for the population-based MINISTOP trial (n=307). Light-intensity PA (LPA), moderate-intensity PA (MPA), vigorous-intensity PA (VPA), moderate-to-vigorous PA (MVPA) and SB were measured using accelerometry (ActiGraph-wGT3x-BT). Body composition was measured using air-displacement plethysmography, and physical fitness (that is, cardiorespiratory fitness, lower and upper body muscular strength and motor fitness) was measured using the PREFIT fitness test battery. Multiple linear regression models adjusted for relevant confounders, and in addition, isotemporal substitution models were applied. Greater MVPA was associated with lower fat mass percent (%FM, P=0.015), and greater VPA and MVPA were associated with higher fat-free mass index (FFMI, P=0.002 and P=0.011). In addition, greater VPA and MVPA were associated with higher scores for all physical fitness tests (P=0.042 to P<0.001). The results for MVPA were primarily due to VPA. SB was associated with weaker handgrip strength (P=0.031) when PA was not adjusted, but after adjusting also for VPA, the significant association disappeared (P=0.25). Substituting 5 min per day of SB, LPA or MPA with 5 min per day of VPA was associated with higher FFMI and better scores for cardiorespiratory fitness and motor fitness. Correspondingly, substituting 5 min per day of VPA with SB or LPA was associated with weaker performance for lower muscular strength. Time spent on VPA was associated with higher FFMI and better physical fitness. The results suggest that promoting VPA may be important to improve childhood body composition and physical fitness already at an early age.

The present study aimed to determine relationships between intramyocellular lipid and biochemical profiles or muscle strength in elderly (n=15; mean age, 71years) and young (n=15; mean age, 21years) male and female adults. Levels of intramyocellular lipid in the vastus lateralis and biceps femoris muscles were determined using 1 H-magnetic resonance spectroscopy. Fasting blood samples were collected to measure levels of glucose, insulin, haemoglobin A1c, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, free fatty acid, triglyceride, adiponectin, and high-sensitivity C-reactive protein. Muscle strength was assessed as maximal voluntary contraction during isometric knee extension. Muscle cross-sectional area in the vastus lateralis was measured using magnetic resonance imaging. Specific force (Ncm-2 ) indicating force generation capacity was calculated as muscle strength (N) divided by the muscle cross-sectional area of the vastus lateralis (cm2 ). The intramyocellular lipid content was similar in both muscles in both groups. The intramyocellular lipid content in the biceps femoris significantly correlated with serum free fatty acid levels (r=0·62, P<0·05), and that in the vastus lateralis significantly and inversely correlated with specific force (r=-0·58, P<0·05) in the young, but not in the elderly adults. The relationship between the intramyocellular lipid content in the thigh muscles and biochemical profiles, or specific force differed between elderly and young adults. Age-associated changes in morphology, function and metabolic factors apparently influence intramyocellular lipid metabolism in the thigh muscles.

Objectives This study aimed to examine the association and dose-relationship between different intensities of work-related and leisure-time physical activity (PA) and biological age (BA). Design: A cross-sectional study. Setting and participants: We used data of 5,216 participants aged 45 and over in the National Health and Nutrition Examination Surveys (NHANES). Measurements: PA was self-reported using the Global Physical Activity Questionnaire (GPAQ), and BAs were calculated by the PhenoAge and Klemera-Doubal method (KDM). In the analyses, survey-weighted generalized linear models were used to explore associations between PA and BAs. Restricted cubic spline characterized the dose-response relationship of PA and BAs. Subgroup analyses were conducted by age, sex, and ethnicity. Results Work-related light-intensity PA (LPA) was significantly associated with younger PhenoAge (β=0.507, 95%CI: -0.957, -0.056, p = 0.031) and KDM (β=0.908, 95%CI: -1.774, -0.042, p = 0.042). There was a U-shaped dose-response relationship between LPA and BAs (all p &amp;lt; 0.05). Leisure-time moderate-intensity PA (MPA) was associated with younger PhenoAge (β=0.789, 95%CI: -1.573, -0.006, p=0.049) and KDM (β=1.910, 95%CI: -3.417, -0.402, p = 0.017). There was a U-shaped dose-response relationship between MPA and BAs (all p &amp;lt; 0.05). In subgroup analyses for older adults, all intensities of PA were significantly associated with decreased BAs (all p &amp;lt; 0.05). Conclusions: Doing PA could delay the BAs, specifically the work-related LPA and leisure-time MPA. Older adults can benefit from all intensities of PA regardless of the PA of different environments and intensities.

BackgroundPrevious studies on physical activity (PA) and pelvic organ prolapse (POP) were largely limited to self-reported PA in athletes, soldiers, and women in postpartum. We aimed to investigate the association of accelerometer-measured PA and sedentary behavior with the risk of POP in middle-aged and elderly women.MethodsIn this prospective cohort derived from the UK Biobank, the intensity and duration of PA and sedentary behavior were measured with wrist-worn accelerometers over a 7-day period in 2013–2015 for 47,674 participants (aged 42.8–77.9 years) without pre-existing POP. Participants were followed up until the end of 2022, during which incident POP was ascertained mainly by the electronic health records. Multivariable-adjusted Cox proportional hazards models and restricted cubic splines were used to assess the associations of interest. Isotemporal substitution models were applied to test the effects of substituting a type of activity with equivalent duration of others.ResultsDuring a median follow-up of 8.0 years, 779 cases of POP were recorded. The duration of light-intensity PA (LPA) was positively whereas sedentary time was negatively associated with the risk of POP. Every additional 1 h/day of LPA elevated the risk of POP by 18% (95% confidence interval [CI], 10%–26%). In contrast, the risk decreased by 5% (95% CI, 0–8%) per 1 h/day increment in sedentary behavior. No associations were found between moderate-intensity PA (MPA) or vigorous-intensity PA (VPA) and POP, except that women who had a history of hysterectomy were more likely to develop POP when performing more VPA (53% higher risk for every additional 15 min/day). Substituting 1 h/day of LPA with equivalent sedentary time was associated with a 18% (95% CI, 11%–24%) lower risk of POP. The risk can also be reduced by 17% (95% CI, 7%–25%) through substituting 30 min/day of LPA with MPA.ConclusionsMore time spent in LPA or less sedentary time was linked to an elevated risk of POP in middle-aged and elderly women, while MPA or VPA was not. Substituting LPA with equivalent duration of sedentary behavior or MPA may lower the risk of POP.

ObjectivesTo investigate associations between daily physical activity, activity intensity and step counts with incident cancer risk.MethodsProspective analysis of UK Biobank participants who wore wrist-based accelerometers for 7 days, followed for...

ObjectivesRecently, isotemporal substitution has been developed to substitute activity time for an equivalent amount of another activity. This study employed this method to demonstrate the effects of replacing sedentary behavior (SB) time with an equivalent amount of light-intensity physical activity (LPA) and moderate-to-vigorous intensity physical activity (MVPA) on the risk for different severities of frailty.MethodsA total of 886 older adults (average age 73.6 years, female 70%) participated in this cross-sectional study. Frailty status was assessed according to the cardiovascular health study criteria.Main outcome measuresWrist-worn accelerometers were used to measure SB, LPA, and MVPA. Isotemporal substitution models were applied to show the estimated effects of substituting 30 min of SB with an equal amount of time spent in LPA or MVPA on the risk for pre-frailty and frailty.ResultsThe physical activity level and SB were not associated with the incidence of pre-frailty. However, a 16% (OR: 0.84; 95% CI: 0.78–0.90) and 42% (OR: 0.58; 95% CI: 0.37–0.92) decrease in frailty risk was noted when SB was substituted with LPA and MVPA, respectively, in the crude model. In the adjusted model, the significant effect was sustained for LPA (OR: 0.86; 95% CI: 0.80–0.92) but not for MVPA (OR: 0.74; 95% CI: 0.47–1.17).ConclusionsThis study indicates that replacing 30 min of SB with an equivalent amount of LPA decreases the risk for frailty in older adults. Moreover, increasing LPA seems more feasible than increasing MVPA in older adults, with substantial benefit.

Past research has indicated that the relationship between energy expenditure and accelerometer output is different between adults with and without Down syndrome (DS). This suggests a need for DS-specific cut points for determining levels of sedentary behavior and physical activity from accelerometer output for adults with DS. PURPOSE: To develop accelerometer output cut points for sedentary behavior and moderate and vigorous intensity physical activity for adults with DS. METHODS: Sixteen adults with DS (10 men & 6 women; age 31 ± 15 years) performed 12 tasks each lasting 6 min: sitting; playing app on tablet; drawing; folding clothes; sweeping; fitness circuit; moving a box; basketball; standing; and walking at the preferred speed and at 0.8 and 1.4 m.s-1. We measured the rate of oxygen uptake with portable indirect calorimetry (K4b2, Cosmed) and expressed it in Metabolic Equivalents (METs). Output from a triaxial accelerometer (wGT3X-BT, Actigraph) worn on the non-dominant hip was determined as Vector Magnitude. Receiver Operating Characteristic (ROC) curves were used to identify Vector Magnitude cut points for sedentary behavior and moderate (3.0 - 5.99 METs) and vigorous (≥6 METs) intensity physical activity. Overall performance of classification models was assessed with the area under the ROC curve. Optimal cut points maximizing sensitivity and specificity were selected based on Youden’s index. RESULTS: Area under the ROC curve was high for all models: (a) sedentary behavior (0.96; 95% CI: 0.93 - 0.98); (b) moderate intensity physical activity (0.92; 95% CI: 0.88 - 0.96); and (c) vigorous intensity physical activity (0.92; 95% CI: 0.85 - 0.99). The optimal Vector Magnitude cut points were: (a) sedentary behavior ≤236 counts·min-1 (sensitivity 0.98; specificity 0.90; Youden’s index 0.88); (b) moderate-intensity physical activity ≤2167 counts·min-1 (sensitivity 0.99; specificity 0.82; Youden’s index 0.81); and (c) vigorous-intensity physical activity ≥4200 counts·min-1 (sensitivity 1.00; specificity 0.84; Youden’s index 0.84). CONCLUSION: This study offers the first DS-specific accelerometer output cut-points for classifying sedentary behavior and intensity of physical activity in adults with DS. Overall classification accuracy was excellent. Supported by NIH Grant R15HD098660

The accumulation of intramyocellular lipid (IMCL) and extramyocellular lipid (EMCL) is associated with arterial stiffness in middle-aged and older adults. Habitual aerobic exercise induces the improvement of arterial stiffness with reduction in fat accumulation. However, the relationship between aerobic exercise-induced changes in muscular lipids and arterial stiffness remains unclear. The purpose of this study was to investigate whether habitual aerobic exercise-induced changes in IMCL and EMCL content would lead to an improvement of arterial stiffness. First, in a cross-sectional study, we investigated whether cardiorespiratory fitness level affects the association between IMCL or EMCL content and arterial stiffness in 60 middle-aged and older subjects (61.0±1.3 years). Second, in an intervention study, we examined whether aerobic exercise training-induced changes in IMCL and EMCL content are associated with a reduction in arterial stiffness in 18 middle-aged and older subjects (67.0±1.7 years). In the cross-sectional study, IMCL content was negatively correlated with brachial-ankle pulse wave velocity (baPWV) (r=-0.47, P<0.05), whereas EMCL content was positively correlated with baPWV (r=0.48, P<0.05) in the low-fitness group, but was not correlated in the high-fitness group. Furthermore, 8-week aerobic exercise training in older adults increased IMCL content and reduced EMCL content. The training-induced change in baPWV was negatively correlated with training-induced changes in IMCL but was positively correlated with training-induced changes in EMCL. These findings suggest that aerobic exercise training-induced changes in IMCL and EMCL content may be related to a reduction in arterial stiffness in middle-aged and older adults.

Objectively measured physical activity is associated with dorsolateral prefrontal cortex volume in older adults

Physically active video gaming (AVG) provides a technologically-modern, convenient means of increasing physical activity (PA). This study examined cardiovascular, metabolic, and perceptual responses in young adult (AP) and older adult (OP) participants engaging in Wii FitTM AVG play, and compared PA levels during play to recommended PA levels. Heart rate (HR), percent heart rate reserve (%HRR), oxygen consumption (VO2), energy expenditure (EE), rating of perceived exertion (RPE), enjoyment level (EL), and step count data were obtained from 10 YP and 10 OP during 15 minutes of rest and four 15-minute bouts of Wii FitTM activities (yoga, balance, aerobics, strength). For all participants, AVG significantly increased HR, VO2, and EE measures above rest, with significant between-activity differences. Responses were similar between YP and OP, except that the activities were more intense for OP, in terms of %HRR and RPE. Most games elicited responses consistent with light-intensity PA, though peak HR and VO2 values for aerobic and strength games met or approached recommended PA intensities. Wii FitTM appears to provide an enjoyable form of light PA for both YP and OP, which can reduce inactive screen time and provide beneficial cardiovascular, musculoskeletal, and metabolic stimulation.

Introduction Accurate measurement of physical activity (PA) in older adults is important, both in health research and personalized prevention. Accelerometers, used to overcome the limitations of self-reporting, were initially worn on the hips, but are increasingly worn on the non-dominant wrist. While this can improve wear compliance, the accuracy of PA intensity classification can be compromised. Given the high prevalence of mild to severe hearing loss in the older population, this study explores a novel approach: integrating an accelerometer into a hearing aid (ear sensor). We aimed to assess its accuracy and compare it to research-grade sensors worn at different locations. Methods 60 middle-aged to older adults (64.0 ± 8.0 years, 48% women) were included in this study. Each subject performed 12-13 different activities, which were pseudo-randomly selected from a list of 33 activities of daily living. Each activity lasted 8 min and included sedentary activities (e.g., lying, playing cards) low-intensity activities (e.g., hanging laundry), activities of changing intensity or without physical displacement (e.g., yoga, squats), indoor activities related to locomotion (e.g., walking, running), outdoor activities (e.g., walking uphill, cycling), and activities with aids (e.g., walking with a stroller). Oxygen consumption was measured via indirect calorimetry and used to classify activity intensity into sedentary behavior (SB, metabolic equivalent of task [MET] &lt; 1.5), light intensity PA (LPA, 1.5 ≤ MET &lt; 3.0), or moderate to vigorous intensity PA (MVPA, MET ≥ 3.0). The ear sensor was placed behind the left ear, while the research-grade sensors were placed on both wrists and ankles, on the hip, chest, and forehead. Estimation of PA intensity classes was done using mean amplitude deviations and ROC analyses. Contingency tables were used to determine classification accuracy. Results Overall accuracy of the ear sensor was 82.6%, performing better than both wrists (left 81.1%, right 76.0%) and both ankles (left 81.1%, right 81.9%), but worse than the forehead (83.6%), hip (85.6%) and the chest (85.9%). ROC analyses show that all sensors can effectively discriminate between sedentary vs. non-sedentary activities (AUC 0.97-0.98, exception ankles: AUC 0.95-0.96) and between MVPA vs. other (AUC 0.96-0.97, exception wrists: AUC 0.89-0.92). Discussion/Conclusion This study is the first to show that an accelerometer integrated into a hearing aid can accurately classify PA intensity and differentiate MVPA and sedentary behavior in older adults. It also confirms previous investigations showing that wrist-worn sensors – although increasingly being used to monitor PA – are less effective in capturing MVPA compared to sensors worn closer to the center of mass (including the head/ear in our study). Although the optimal wear site in older adults is a subject of ongoing debate, our data shows that a sensor integrated into a hearing aid offers a promising balance of classification accuracy and (possibly) user compliance. Further studies should explore integrating in-ear heart rate monitoring to enhance accuracy even further.

The aim of the present study was to investigate the relationship between physical activity (PA) and depressive symptoms in community-dwelling older Japanese adults. A cross-sectional study design was used to obtain data from 3191 community-dwelling older Japanese adults aged 70-95 years. Depressive symptoms were assessed using self-reported scores on the Geriatric Depression Scale-15. PA was objectively measured using an accelerometer worn for a maximum of 40 days, and average daily durations of light-intensity PA (LPA), moderate-to-vigorous intensity PA (MVPA) and step count were calculated. PA was compared between participants with and without depressive symptoms by carrying out analysis of covariance and multivariable logistic regression analysis adjusted for all covariates by using propensity scores. Depressive symptoms were present in 598 participants (19.6%). A comparison of propensity-score adjusted PA showed that step count (5059.6 ± 53.7 vs 5003.0 ± 112.1 count/day; P = 0.652) and moderate-to-vigorous intensity PA duration (23.0 ± 0.4 vs 23.8 ± 0.7 min/day; P = 0.358) were not significantly different between participants with and without depressive symptoms, respectively. However, participants without depressive symptoms had a significantly higher LPA duration than those with depressive symptoms (39.4 ± 0.3 vs 37.3 ± 0.7 min/day, respectively; P < 0.01). The present results suggest that individuals with lower LPA have a higher risk of depressive symptoms. These findings imply that PA recommendations, especially for older adults, should emphasize LPA, which appears to be especially effective at preventing depressive symptoms. Geriatr Gerontol Int 2018; 18: 421-427.