Long-term Changes in Body Composition and Exercise Capacity Following Calorie Restriction and Exercise Training in Older Patients with Obesity and Heart Failure With Preserved Ejection Fraction.

BACKGROUND: Obesity combined with heart failure with preserved ejection fraction (HFpEF) is the dominant form of HF among older persons. In a randomized trial, we previously showed that a 5-month calorie restriction (CR) program, with or without aerobic exercise training (AT), resulted in significant weight and fat loss and improved exercise capacity. However, little is known regarding the long-term effects of these outcomes after a short-term (5-month) intervention of CR with or without AT in older patients with obesity and HFpEF. METHODS: Sixteen participants from either the CR or CR+AT who experienced significant weight loss ≥ 2 kg were reexamined after a long-term follow-up endpoint (28.0 ± 10.8 months) without intervention. The follow-up assessment included body weight and composition via dual-energy X-ray absorptiometry and exhaustive cardiopulmonary treadmill exercise testing. RESULTS: Compared to the 5-month time-point intervention endpoint, at the long-term follow-up endpoint, mean body weight increased +5.2 ± 4.0 kg (90.7 ± 11.2 kg vs 95.9 ± 11.9; P < 0.001) due to increased fat mass (38.9 ± 9.3 vs 43.8 ± 9.8; P < 0.001) with no change in lean mass (49.6 ± 7.1 vs 49.9±7.6; P = 0.67), resulting in worse body composition (decreased lean-to-fat mass). Change in total mass was strongly and significantly correlated with change in fat mass (r = 0.75; P < 0.001), whereas there appeared to be a weaker correlation with change in lean mass (r = 0.50; P = 0.051). Additionally, from the end of the 5-month time-point intervention endpoint to the long-term follow-up endpoint, there were large, significant decreases in VO2peak (-2.2 ± 2.1 mL/kg/min; P = 0.003) and exercise time (-2.4 ± 2.6 min; P = 0.006). There appeared to be an inverse correlation between the change in VO2peak and the change in fat mass (r = -0.52; P = 0.062). CONCLUSION: Although CR and CR+AT in older patients with obesity and HFpEF can improve body composition and exercise capacity significantly, these positive changes diminish considerably during long-term follow-up endpoints, and regained weight is predominantly adipose, resulting in worsened overall body composition compared to baseline. This suggests a need for long-term adherence strategies to prevent weight regain and maintain improvements in body composition and exercise capacity following CR in older patients with obesity and HFpEF.

Effects of Exercise and Weight Loss on Proximal Aortic Stiffness in Older Adults With Obesity.

BACKGROUND: Obesity may accelerate age-related increases in aortic stiffness. Although aerobic exercise training generally has favorable effects on aortic structure and function, exercise alone may not be sufficient to improve aortic stiffness in older adults with obesity. We determined the effects of aerobic exercise training with and without moderate- to high-caloric restriction (CR) on the structure and function of the proximal aorta in 160 older (65-79 years) men and women with obesity (body mass index=30-45 kg/m2). METHODS: Participants were randomly assigned to 1 of 3 groups: aerobic exercise training only (treadmill 4 days/week for 30 minutes at 65% to 70% of heart rate reserve; n=56), aerobic exercise training plus moderate CR (n=55), or aerobic exercise training plus more intensive CR (n=49) for 20 weeks. Aortic pulse wave velocity, aortic distensibility, and other measures of aortic structure and function were assessed by cardiovascular magnetic resonance imaging. Pearson correlation coefficients were examined to assess associations between changes in proximal aortic stiffness and changes in fitness, fatness, and other potential confounders. RESULTS: Weight loss in the aerobic exercise training plus moderate CR (-8.0 kg [95% CI, -9.17 to -6.87]) and aerobic exercise training plus more intensive CR (-8.98 kg [95% CI, -10.23 to -7.73) groups was significantly greater compared with the aerobic exercise training-only group (-1.66 kg [95% CI, -2.94 to -0.38]; P<0.017 for both). There were significant treatment effects for descending aorta distensibility (P=0.008) and strain (P=0.004) and aortic arch pulse wave velocity (P=0.01) with the aerobic exercise training plus moderate CR group having a 21% increase in distensibility (P=0.016) and an 8% decrease in pulse wave velocity (P=0.058). None of the aortic stiffness measures changed significantly in the aerobic exercise training-only or aerobic exercise training plus more intensive CR groups, and there were no significant changes in any other measure of aortic structure or function in these groups. Overall, increases in aortic distensibility were correlated with improvements in body weight and body fat distribution, but these associations were not statistically significant after adjustment for multiple comparisons. CONCLUSIONS: In older adults with obesity, combining aerobic exercise with moderate CR leads to greater improvements in proximal aortic stiffness than exercise alone. Registration: URL: https://clinicaltrials.gov; Unique identifier: NCT01048736.

Six-month changes in ghrelin and glucagon-like peptide-1 with weight loss are unrelated to long-term weight regain in obese older adults.

BACKGROUND AND OBJECTIVE: Weight loss (WL) and subsequent regain are complex physiologic processes, and our understanding of the hormonal changes associated with these processes continues to evolve. We aimed to examine the effects of behavioral WL on 6-month changes in ghrelin and GLP-1 and evaluate the effects of these changes in gut hormones on weight regain among older adults. SUBJECTS AND METHODS: One hundred seventy-seven obese (BMI: 33.5 (3.5) kg/m2) older adults (66.9 ± 4.7 years, 71.2% female, 67.6% white) were randomized to WL (WL; n = 68), WL plus aerobic training (n = 79), or WL plus resistance training (n = 75) for 18 months. Ghrelin, GLP-1, power of food scale (PFS), and weight were measured at baseline, 6 months, and 18 months. RESULTS: There was no differential treatment effect on change in either gut hormone, however, there was a significant time effect across all groups (p < 0.001), with increases in ghrelin (∆ = +106.77 pg/ml; 95% CI = + 84.82, +128.71) and decreases in GLP-1 (∆ = -4.90 pM; 95% CI = -6.27, -3.51) at 6-month. Ratings on the PFS decreased from baseline to 6-month and there was significant loss of weight from baseline to either 6- or 18-month, ∆ = -7.96 kg; 95% CI = -7.95, -8.78 and ∆ = -7.80 kg; 95% CI = -8.93, -6.65, respectively (p < 0.001). Changes in ghrelin and GLP-1 at 6-month did not predict weight regain from 6- to 18-month. DISCUSSION AND CONCLUSION: Among older adults with obesity and cardiometabolic disease, the intensive phase of dietary WL results in increasing levels of ghrelin and decreasing levels of GLP-1 that are unrelated to weight regain a year later. Registered with ClinicalTrials.gov (NCT01547182).

Effect of High-Intensity Strength Training on Knee Pain and Knee Joint Compressive Forces Among Adults With Knee Osteoarthritis: The START Randomized Clinical Trial.

Importance: Thigh muscle weakness is associated with knee discomfort and osteoarthritis disease progression. Little is known about the efficacy of high-intensity strength training in patients with knee osteoarthritis or whether it may worsen knee symptoms. Objective: To determine whether high-intensity strength training reduces knee pain and knee joint compressive forces more than low-intensity strength training and more than attention control in patients with knee osteoarthritis. Design, Setting, and Participants: Assessor-blinded randomized clinical trial conducted at a university research center in North Carolina that included 377 community-dwelling adults (≥50 years) with body mass index (BMI) ranging from 20 to 45 and with knee pain and radiographic knee osteoarthritis. Enrollment occurred between July 2012 and February 2016, and follow-up was completed September 2017. Interventions: Participants were randomized to high-intensity strength training (n = 127), low-intensity strength training (n = 126), or attention control (n = 124). Main Outcomes and Measures: Primary outcomes at the 18-month follow-up were Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) knee pain (0 best-20 worst; minimally clinically important difference [MCID, 2]) and knee joint compressive force, defined as the maximal tibiofemoral contact force exerted along the long axis of the tibia during walking (MCID, unknown). Results: Among 377 randomized participants (mean age, 65 years; 151 women [40%]), 320 (85%) completed the trial. Mean adjusted (sex, baseline BMI, baseline outcome values) WOMAC pain scores at the 18-month follow-up were not statistically significantly different between the high-intensity group and the control group (5.1 vs 4.9; adjusted difference, 0.2; 95% CI, -0.6 to 1.1; P = .61) or between the high-intensity and low-intensity groups (5.1 vs 4.4; adjusted difference, 0.7; 95% CI, -0.1 to 1.6; P = .08). Mean knee joint compressive forces were not statistically significantly different between the high-intensity group and the control group (2453 N vs 2512 N; adjusted difference, -58; 95% CI, -282 to 165 N; P = .61), or between the high-intensity and low-intensity groups (2453 N vs 2475 N; adjusted difference, -21; 95% CI, -235 to 193 N; P = .85). There were 87 nonserious adverse events (high-intensity, 53; low-intensity, 30; control, 4) and 13 serious adverse events unrelated to the study (high-intensity, 5; low-intensity, 3; control, 5). Conclusions and Relevance: Among patients with knee osteoarthritis, high-intensity strength training compared with low-intensity strength training or an attention control did not significantly reduce knee pain or knee joint compressive forces at 18 months. The findings do not support the use of high-intensity strength training over low-intensity strength training or an attention control in adults with knee osteoarthritis. Trial Registration: ClinicalTrials.gov Identifier: NCT01489462.

Physiological Aging: Links Among Adipose Tissue Dysfunction, Diabetes, and Frailty.

Advancing age is associated with progressive declines in physiological function that lead to overt chronic disease, frailty, and eventual mortality. Importantly, age-related physiological changes occur in cellularity, insulin-responsiveness, secretory profiles, and inflammatory status of adipose tissue, leading to adipose tissue dysfunction. Although the mechanisms underlying adipose tissue dysfunction are multifactorial, the consequences result in secretion of proinflammatory cytokines and chemokines, immune cell infiltration, an accumulation of senescent cells, and an increase in senescence-associated secretory phenotype (SASP). These processes synergistically promote chronic sterile inflammation, insulin resistance, and lipid redistribution away from subcutaneous adipose tissue. Without intervention, these effects contribute to age-related systemic metabolic dysfunction, physical limitations, and frailty. Thus adipose tissue dysfunction may be a fundamental contributor to the elevated risk of chronic disease, disability, and adverse health outcomes with advancing age.

Impact of Diet and/or Exercise Intervention on Infrapatellar Fat Pad Morphology: Secondary Analysis from the Intensive Diet and Exercise for Arthritis (IDEA) Trial.

OBJECTIVES: The infrapatellar fat pad (IPFP) represents intra-articular adipose tissue that may contribute to intra-articular inflammation and pain by secretion of proinflammatory cytokines. Here we examined the impact of weight loss by diet and/or exercise interventions on the IPFP volume. METHODS: Intensive Diet and Exercise for Arthritis (IDEA) was a single-blinded, single-center, 18-month, prospective, randomized controlled trial that enrolled 454 overweight and obese older adults with knee pain and radiographic osteoarthritis. Participants were randomized to 1 of 3 groups: exercise-only control (E), diet-induced weight loss (D), and diet-induced weight loss + exercise (D+E). In a subsample (n = 106; E: n = 36, D: n = 35, and D+E: n = 35), magnetic resonance images were acquired at baseline and at the 18-month follow-up, from which we analyzed IPFP volume, surface areas, and thickness in this secondary analysis. RESULTS: The average weight loss amounted to 1.0% in the E group, 10.5% in the D group, and 13.0% in the D+E group. A significant (p < 0.01) reduction in IPFP volume was observed in the E (2.1%), D (4.0%), and D+E (5.2%) groups. The IPFP volume loss in the D+E group was significantly greater than that in the E group (p < 0.05) when not adjusting for parallel comparisons. Across intervention groups, there were significant correlations between IPFP volume change, individual weight loss (r = 0.40), and change in total body fat mass (dual-energy X-ray absorptiometry; r = 0.44, n = 88) and in subcutaneous thigh fat area (computed tomography; r = 0.32, n = 82). CONCLUSIONS: As a potential link between obesity and knee osteoarthritis, the IPFP was sensitive to intervention by diet and/or exercise, and its reduction was correlated with changes in weight and body fat.

Gait speed response to aerobic versus resistance exercise training in older adults.

BACKGROUND: Little is known about the comparative effect of aerobic training (AT) versus resistance training (RT) on gait speed, a strong predictor of disability. AIMS: To compare the effect of AT versus RT on gait speed and other functional measures. METHODS: Overweight and obese [body mass index (BMI) ≥27.0 kg/m2] sedentary men and women aged 65-79 years engaged in 5 months of either 4 days/weeks moderate-intensity treadmill walking, AT, (n = 44) or 3 days/weeks moderate-intensity RT (n = 56). Usual-pace gait speed, fast-pace gait speed and short physical performance battery (SPPB) were evaluated in all participants before and after training. Peak oxygen consumption (VO2peak) was assessed in AT participants only, and knee extensor strength was assessed in RT participants. RESULTS: Both AT and RT resulted in clinically significant improvements in usual-pace gait speed (0.08 ± 0.14 and 0.08 ± 0.17 m/s, respectively, both p < 0.05) and SPPB (0.53 ± 1.40 and 0.53 ± 1.20 points, both p < 0.05) and chair rise time (-1.2 ± 3.2 and -1.7 ± 3.0 s, p < 0.05). Only AT improved fast-pace gait speed (0.11 ± 0.10 m/s, p < 0.05). In the RT participants, lower baseline knee strength was associated with less improvement in usual-pace gait speed. In AT participants, lower baseline VO2peak was associated with less improvement in chair rise time and self-reported disability. DISCUSSION: While both AT and RT improved usual-pace gait speed, only AT improved fast-pace gait speed. Lower baseline fitness was associated with less improvement with training. CONCLUSION: Research to directly compare which mode of training elicits the maximum improvement in older individuals with specific functional deficits could lead to better intervention targeting.

Impact of methods used to express levels of circulating fatty acids on the degree and direction of associations with blood lipids in humans.

Numerous studies have examined relationships between disease biomarkers (such as blood lipids) and levels of circulating or cellular fatty acids. In such association studies, fatty acids have typically been expressed as the percentage of a particular fatty acid relative to the total fatty acids in a sample. Using two human cohorts, this study examined relationships between blood lipids (TAG, and LDL, HDL or total cholesterol) and circulating fatty acids expressed either as a percentage of total or as concentration in serum. The direction of the correlation between stearic acid, linoleic acid, dihomo-γ-linolenic acid, arachidonic acid and DHA and circulating TAG reversed when fatty acids were expressed as concentrations v. a percentage of total. Similar reversals were observed for these fatty acids when examining their associations with the ratio of total cholesterol:HDL-cholesterol. This reversal pattern was replicated in serum samples from both human cohorts. The correlations between blood lipids and fatty acids expressed as a percentage of total could be mathematically modelled from the concentration data. These data reveal that the different methods of expressing fatty acids lead to dissimilar correlations between blood lipids and certain fatty acids. This study raises important questions about how such reversals in association patterns impact the interpretation of numerous association studies evaluating fatty acids and their relationships with disease biomarkers or risk.

Effect of Caloric Restriction or Aerobic Exercise Training on Peak Oxygen Consumption and Quality of Life in Obese Older Patients With Heart Failure With Preserved Ejection Fraction: A Randomized Clinical Trial.

IMPORTANCE: More than 80% of patients with heart failure with preserved ejection fraction (HFPEF), the most common form of heart failure among older persons, are overweight or obese. Exercise intolerance is the primary symptom of chronic HFPEF and a major determinant of reduced quality of life (QOL). OBJECTIVE: To determine whether caloric restriction (diet) or aerobic exercise training (exercise) improves exercise capacity and QOL in obese older patients with HFPEF. DESIGN, SETTING, AND PARTICIPANTS: Randomized, attention-controlled, 2 × 2 factorial trial conducted from February 2009 through November 2014 in an urban academic medical center. Of 577 initially screened participants, 100 older obese participants (mean [SD]: age, 67 years [5]; body mass index, 39.3 [5.6]) with chronic, stable HFPEF were enrolled (366 excluded by inclusion and exclusion criteria, 31 for other reasons, and 80 declined participation). INTERVENTIONS: Twenty weeks of diet, exercise, or both; attention control consisted of telephone calls every 2 weeks. MAIN OUTCOMES AND MEASURES: Exercise capacity measured as peak oxygen consumption (V̇O2, mL/kg/min; co-primary outcome) and QOL measured by the Minnesota Living with Heart Failure (MLHF) Questionnaire (score range: 0-105, higher scores indicate worse heart failure-related QOL; co-primary outcome). RESULTS: Of the 100 enrolled participants, 26 participants were randomized to exercise; 24 to diet; 25 to exercise + diet; 25 to control. Of these, 92 participants completed the trial. Exercise attendance was 84% (SD, 14%) and diet adherence was 99% (SD, 1%). By main effects analysis, peak V̇O2 was increased significantly by both interventions: exercise, 1.2 mL/kg body mass/min (95% CI, 0.7 to 1.7), P < .001; diet, 1.3 mL/kg body mass/min (95% CI, 0.8 to 1.8), P < .001. The combination of exercise + diet was additive (complementary) for peak V̇O2 (joint effect, 2.5 mL/kg/min). There was no statistically significant change in MLHF total score with exercise and with diet (main effect: exercise, -1 unit [95% CI, -8 to 5], P = .70; diet, -6 units [95% CI, -12 to 1], P = .08). The change in peak V̇O2 was positively correlated with the change in percent lean body mass (r = 0.32; P = .003) and the change in thigh muscle:intermuscular fat ratio (r = 0.27; P = .02). There were no study-related serious adverse events. Body weight decreased by 7% (7 kg [SD, 1]) in the diet group, 3% (4 kg [SD, 1]) in the exercise group, 10% (11 kg [SD, 1] in the exercise + diet group, and 1% (1 kg [SD, 1]) in the control group. CONCLUSIONS AND RELEVANCE: Among obese older patients with clinically stable HFPEF, caloric restriction or aerobic exercise training increased peak V̇O2, and the effects may be additive. Neither intervention had a significant effect on quality of life as measured by the MLHF Questionnaire. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00959660.

Genetic influence on exercise-induced changes in physical function among mobility-limited older adults.

To date, physical exercise is the only intervention consistently demonstrated to attenuate age-related declines in physical function. However, variability exists in seniors' responsiveness to training. One potential source of variability is the insertion (I allele) or deletion (D allele) of a 287 bp fragment in intron 16 of the angiotensin-converting enzyme (ACE) gene. This polymorphism is known to influence a variety of physiological adaptions to exercise. However, evidence is inconclusive regarding the influence of this polymorphism on older adults' functional responses to exercise. This study aimed to evaluate the association of ACE I/D genotypes with changes in physical function among Caucasian older adults (n = 283) following 12 mo of either structured, multimodal physical activity or health education. Measures of physical function included usual-paced gait speed and performance on the Short Physical Performance Battery (SPPB). After checking Hardy-Weinberg equilibrium, we used using linear regression to evaluate the genotype*treatment interaction for each outcome. Covariates included clinic site, body mass index, age, sex, baseline score, comorbidity, and use of angiotensin receptor blockers or ACE inhibitors. Genotype frequencies [II (19.4%), ID (42.4%), DD (38.2%)] were in Hardy-Weinberg equilibrium (P > 0.05). The genotype*treatment interaction was statistically significant for both gait speed (P = 0.002) and SPPB (P = 0.020). Exercise improved gait speed by 0.06 ± 0.01 m/sec and SPPB score by 0.72 ± 0.16 points among those with at least one D allele (ID/DD carriers), but function was not improved among II carriers. Thus, ACE I/D genotype appears to play a role in modulating functional responses to exercise training in seniors.

The effects of a long-term physical activity intervention on serum uric acid in older adults at risk for physical disability.

Observational studies show a relationship between elevated serum uric acid (UA) and better physical performance and muscle function. The purpose of this paper was to determine whether regular participation in an exercise intervention, known to improve physical functioning, would result in increased serum UA. For this study, 424 older adults at risk for physical disability were randomized to participate in either a 12-mo moderate-intensity physical activity (PA) or a successful aging (SA) health education intervention. UA was measured at baseline, 6, and 12 mo (n = 368, 341, and 332, respectively). Baseline UA levels were 6.03 ± 1.52 mg/dl and 5.94 ± 1.55 mg/dl in the PA and SA groups, respectively. The adjusted mean UA at month 12 was 4.8% (0.24 mg/dl) higher in the PA compared with the SA group (p = .028). Compared with a health education intervention, a 1-yr PA intervention results in a modest increase in systemic concentration of UA in older adults at risk for mobility disability.

Serum factors mediate changes in mitochondrial bioenergetics associated with diet and exercise interventions.

Mitochondrial improvements resulting from behavioral interventions, such as diet and exercise, are systemic and apparent across multiple tissues. Here, we test the hypothesis that factors present in serum, and therefore circulating throughout the body, can mediate changes in mitochondrial function in response to intervention. To investigate this, we used stored serum from a clinical trial comparing resistance training (RT) and RT plus caloric restriction (RT + CR) to examine effects of blood borne circulating factors on myoblasts in vitro. We report that exposure to dilute serum is sufficient to mediate bioenergetic benefits of these interventions. Additionally, serum-mediated bioenergetic changes can differentiate between interventions, recapitulate sex differences in bioenergetic responses, and is linked to improvements in physical function and inflammation. Using metabolomics, we identified circulating factors associated with changes in mitochondrial bioenergetics and the effects of interventions. This study provides new evidence that circulating factors play a role in the beneficial effects of interventions that improve healthspan among older adults. Understanding the factors that drive improvements in mitochondrial function is a key step towards predicting intervention outcomes and developing strategies to countermand systemic age-related bioenergetic decline.

Caloric Restriction Intervention Alters Specific Circulating Biomarkers of the Senescence-Associated Secretome in Middle-Aged and Older Adults With Obesity and Prediabetes in an 18-Week Randomized Controlled Trial.

Cellular senescence is a biological aging process that is exacerbated by obesity and leads to inflammation and age- and obesogenic-driven chronic diseases including type 2 diabetes. Caloric restriction (CR) may improve metabolic function in part by reducing cellular senescence and the pro-inflammatory senescence-associated phenotype (SASP). We conducted an ancillary investigation of an 18-week randomized controlled trial (RCT) of CR (n = 31) or Control (n = 27) in 58 middle-aged/older adults (57.6 ±â€…5.8 years; 75% Women) with obesity and prediabetes. We measured mRNA expression of select senescence and apoptosis genes in blood CD3 + T cells (qRT-PCR) and a panel of 25 plasma SASP proteins (Luminex/multiplex; ELISA). Participants randomized to CR lost -10.8 ±â€…0.9 kg (-11.3% ±â€…5.4%) over 18 weeks compared with +0.5 ±â€…0.9 kg (+0.03% ±â€…3.5%) in Control group. T-cell expression of senescence biomarkers, p16INK4a and p21CIP1/WAF1, and apoptosis markers, BCL2L1 and BAK1, was not different between CR and Control groups in age, race, and sex-adjusted mixed models (p > .05, all). Iterative principal axis factor analysis was used to develop composite SASP Factors, and the Factors comprising TNFRI, TNFRII, uPAR, MMP1, GDF15, OPN, Fas, and MPO were significantly altered with CR intervention (age, sex, race-adjusted mixed model time × treatment F = 4.17, p ≤ .05) and associated with the degree of weight loss (R2 = 0.12, p ≤ .05). Our study provides evidence from an RCT that specific circulating biomarkers of senescent cell burden are changed by CR in middle-aged and older adults with obesity and prediabetes. Future studies compare tissue and circulating levels of p16INK4a and pro-inflammatory SASP biomarkers in other populations, and interventions.

Role of Walking Energetics and Perceived Fatigability Differs by Gait Speed: The Study of Muscle, Mobility and Aging (SOMMA).

BACKGROUND: Slower gait speed may be driven by greater energy deficits and fatigability among older adults. We examined associations of walking energetics and perceived physical fatigability with gait speed among slower and faster walkers. Additionally, we used statistical mediation to examine the role of fatigability in the associations of walking energetics and gait speed using the Study of Muscle, Mobility and Aging (SOMMA). METHODS: Perceived physical fatigability was assessed using the Pittsburgh Fatigability Scale (PFS) Physical score (range 0-50, higher = greater). A 3-phase cardiopulmonary exercise treadmill test collected peak oxygen consumption (VO2peak, mL/kg/min), energetic cost of walking (ECW, mL/kg/m), and cost-capacity ratio (VO2/VO2peak*100, %). Slower (<1.01 m/s) versus faster (≥1.01 m/s) walkers were classified using median 4-m gait speed. Linear regressions and statistical mediation analyses were conducted. RESULTS: Slower walkers had lower VO2peak, higher ECW at preferred walking speed (PWS), and greater PFS Physical score compared to faster walkers (all p < .05; N = 849). One standard deviation (1-SD) higher VO2peak was associated with 0.1 m/s faster gait speed, while 1-SD higher ECW PWS, cost-capacity ratio at PWS and slow walking speed (SWS), and PFS Physical score were associated with 0.02-0.23 m/s slower gait speed. PFS Physical score was a significant statistical mediator in the associations between VO2peak (15.2%), SWS cost-capacity ratio (15.9%), and ECW PWS (10.7%) with gait speed and was stronger among slower walkers. CONCLUSIONS: Slower walkers may be more influenced by perceptions of fatigue in addition to walking energetics. Our work highlights the importance of targeting both energetics and perceived fatigability to prevent mobility decline.

Usual-paced 400 m long distance corridor walk estimates cardiorespiratory fitness among older adults: The Study of Muscle, Mobility and Aging.

BACKGROUND: Cardiopulmonary exercise testing (CPET), the gold-standard method to quantify cardiorespiratory fitness (CRF), is not always feasible due to cost, access, and burden. The usual-paced 400 m long distance corridor walk (LDCW), a measure of mobility among older adults, may provide an alternate method to assess CRF. The purpose of this study was to develop and validate an estimating equation to estimate VO2 peak from average 400 m walking speed (WS) among participants in the Study of Muscle, Mobility and Aging (SOMMA). METHODS: At baseline, women (58%) and men age 70 years and older enrolled in SOMMA (N = 820, 76.2 ± 4.9 years, 86% Non-Hispanic White) completed a 400 m LDCW (400 m WS = 400 m/completion time in seconds) and symptom-limited maximal CPET (Modified Balke Protocol). VO2 peak (mL/kg/min) was considered the highest 30-second average oxygen consumption during CPET. Other covariates included: age, sex, race, physical activity (7-day wrist-worn accelerometer), physical function (Short Physical Performance Battery, range 0-12), perceived physical fatigability (Pittsburgh Fatigability Scale, range 0-50), and Borg Rating of Perceived Exertion (RPE, range 6-20) at completion of the 400 m LDCW. Stepwise linear regression was used. Internal validation was completed using data-splitting method (70%; 30%). RESULTS: Mean VO2 peak was 20.2 ± 4.8 mL/kg/min and mean 400 m WS was 1.06 ± 0.2 m/s. Each 0.05 m/s increment in 400 m WS was associated with a 0.40 mL/kg/min higher VO2 peak after covariate adjustment. An estimating equation including 400 m WS, age, sex, race, and RPE was developed. Internal validation showed low overall bias (-0.26) and strong correlation (r = 0.71) between predicted and measured VO2 peak values. Bland-Altman plot and regression analyses indicated predicted VO2 peak was an acceptable alternative, despite mean underestimation of 4.53 mL/kg/min among the highly fit. CONCLUSIONS: Usual-paced 400 m LDCW strongly correlates with direct measures of CRF during CPET in older adults with lower fitness and can be used to test both fitness and function.

The Bone, Exercise, Alendronate, and Caloric Restriction (BEACON) trial design and methods.

BACKGROUND: Among older adults living with obesity, intentional weight loss (WL) improves prognosis of many comorbidities. However, concomitant decline in bone mineral density (BMD) limits overall benefit of WL by increasing osteoporotic fracture risk. Identification of intervention strategies to maximize body fat loss, while minimizing harm to the musculoskeletal system, is an important area of clinical research. The main objective of the Bone, Exercise, Alendronate, and Caloric Restriction (BEACON) trial (NCT05764733) is to compare the independent and combined effects of a 12-month intervention of resistance training (RT) plus bone-loading exercises and bisphosphonate use on dietary WL-associated bone loss among 308 older (≥60 years) adults living with an indication for WL and bisphosphonate use. METHODS: All participants will receive the same group-mediated dietary intervention targeting 8-10 % WL and be randomized to one of four groups: no RT and placebo capsules (NoRT+PL); progressive RT plus bone-loading exercises and placebo capsules (RT++PL); no RT and oral bisphosphonate (70 mg weekly oral alendronate; NoRT+BIS); or progressive RT plus bone-loading exercises and oral bisphosphonate (RT++BIS). Total hip areal (a)BMD measured via dual-energy x-ray absorptiometry (DXA) is the primary, powered study outcome. Secondary skeletal outcome measures include femoral neck and lumbar spine aBMD, high resolution peripheral quantitative computed tomography (HRpQCT) bone assessments of the radius and tibia, and biomarkers of bone turnover. DISCUSSION: BEACON will address an understudied, yet important, clinical research question by studying the independent and combined effects of two scalable intervention strategies aimed at optimizing skeletal integrity in older adults undergoing WL. CLINICAL TRIALS REGISTRATION: NCT05764733.

Sex Differences in the Association between Skeletal Muscle Energetics and Perceived Physical Fatigability: The Study of Muscle, Mobility and Aging (SOMMA).

Greater perceived physical fatigability and lower skeletal muscle energetics are predictors of mobility decline. Characterizing associations between muscle energetics and perceived fatigability may provide insight into potential targets to prevent mobility decline. We examined associations of in vivo (maximal ATP production, ATPmax) and ex vivo (maximal carbohydrate supported oxidative phosphorylation [max OXPHOS] and maximal fatty acid supported OXPHOS [max FAO OXPHOS]) measures of mitochondrial energetics with two measures of perceived physical fatigability, Pittsburgh Fatigability Scale (PFS, 0-50, higher=greater) and Rating of Perceived Exertion (RPE Fatigability, 6-20, higher=greater) after a slow treadmill walk. Participants from the Study of Muscle, Mobility and Aging (N=873) were 76.3±5.0 years old, 59.2% women, and 85.3% White. Higher muscle energetics (both in vivo and ex vivo ) were associated with lower perceived physical fatigability, all p<0.03. When stratified by sex, higher ATPmax was associated with lower PFS Physical for men only; higher max OXPHOS and max FAO OXPHOS were associated with lower RPE fatigability for both sexes. Higher skeletal muscle energetics were associated with 40-55% lower odds of being in the most (PFS≥25, RPE Fatigability≥12) vs least (PFS 0-4, RPE Fatigability 6-7) severe fatigability strata, all p<0.03. Being a woman was associated with 2-3 times higher odds of being in the most severe fatigability strata when controlling for ATPmax but not the in vivo measures (p<0.05). Better mitochondrial energetics were linked to lower fatigability and less severe fatigability in older adults. Findings imply that improving skeletal muscle energetics may mitigate perceived physical fatigability and prolong healthy aging.

Sex differences in the association between skeletal muscle energetics and perceived physical fatigability: the Study of Muscle, Mobility and Aging (SOMMA).

Greater perceived physical fatigability and lower skeletal muscle energetics are both predictors of mobility decline. Characterizing associations between muscle energetics and perceived fatigability may provide insight into potential targets to prevent mobility decline. We examined associations of in vivo (maximal ATP production, ATPmax) and ex vivo (maximal carbohydrate supported oxidative phosphorylation [max OXPHOS] and maximal fatty acid supported OXPHOS [max FAO OXPHOS]) measures of mitochondrial energetics with two measures of perceived physical fatigability, Pittsburgh Fatigability Scale (PFS, 0-50, higher = greater) and Rating of Perceived Exertion (RPE Fatigability, 6-20, higher = greater) after a slow treadmill walk. Participants from the Study of Muscle, Mobility and Aging (N = 873) were 76.3 ± 5.0 years old, 59.2% women, and 85.3% White. Higher muscle energetics (both in vivo and ex vivo) were associated with lower perceived physical fatigability, all p < 0.03. When stratified by sex, higher ATPmax was associated with lower PFS Physical for men only; higher max OXPHOS and max FAO OXPHOS were associated with lower RPE Fatigability for both sexes. Higher skeletal muscle energetics were associated with 40-55% lower odds of being in the most (PFS ≥ 25, RPE Fatigability ≥ 12) vs least (PFS 0-4, RPE Fatigability 6-7) severe fatigability strata, all p < 0.03. Being a woman was associated with 2-3 times higher odds of being in the most severe fatigability strata when controlling for ATPmax but not the ex vivo measures (p < 0.05). Better mitochondrial energetics were linked to lower fatigability and less severe fatigability in older adults. Findings imply that improving skeletal muscle energetics may mitigate perceived physical fatigability and prolong healthy aging.

Strength Training for Arthritis Trial (START): design and rationale.

BACKGROUND: Muscle loss and fat gain contribute to the disability, pain, and morbidity associated with knee osteoarthritis (OA), and thigh muscle weakness is an independent and modifiable risk factor for it. However, while all published treatment guidelines recommend muscle strengthening exercise to combat loss of muscle mass and strength in knee OA patients, previous strength training studies either used intensities or loads below recommended levels for healthy adults or were generally short, lasting only 6 to 24 weeks. The efficacy of high-intensity strength training in improving OA symptoms, slowing progression, and affecting the underlying mechanisms has not been examined due to the unsubstantiated belief that it might exacerbate symptoms. We hypothesize that in addition to short-term clinical benefits, combining greater duration with high-intensity strength training will alter thigh composition sufficiently to attain long-term reductions in knee-joint forces, lower pain levels, decrease inflammatory cytokines, and slow OA progression. METHODS/DESIGN: This is an assessor-blind, randomized controlled trial. The study population consists of 372 older (age ≥ 55 yrs) ambulatory, community-dwelling persons with: (1) mild-to-moderate medial tibiofemoral OA (Kellgren-Lawrence (KL) = 2 or 3); (2) knee neutral or varus aligned knee ( -2° valgus ≤ angle ≤ 10° varus); (3) 20 kg.m-2 ≥ BMI ≤ 45 kg.m-2; and (3) no participation in a formal strength-training program for more than 30 minutes per week within the past 6 months. Participants are randomized to one of 3 groups: high-intensity strength training (75-90% 1Repetition Maximum (1RM)); low-intensity strength training (30-40%1RM); or healthy living education. The primary clinical aim is to compare the interventions' effects on knee pain, and the primary mechanistic aim is to compare their effects on knee-joint compressive forces during walking, a mechanism that affects the OA disease pathway. Secondary aims will compare the interventions' effects on additional clinical measures of disease severity (e.g., function, mobility); disease progression measured by x-ray; thigh muscle and fat volume, measured by computed tomography (CT); components of thigh muscle function, including hip abductor strength and quadriceps strength, and power; additional measures of knee-joint loading; inflammatory and OA biomarkers; and health-related quality of life. DISCUSSION: Test-retest reliability for the thigh CT scan was: total thigh volume, intra-class correlation coefficients (ICC) = 0.99; total fat volume, ICC = 0.99, and total muscle volume, ICC = 0.99. ICC for both isokinetic concentric knee flexion and extension strength was 0.93, and for hip-abductor concentric strength was 0.99. The reliability of our 1RM testing was: leg press, ICC = 0.95; leg curl, ICC = 0.99; and leg extension, ICC = 0.98. Results of this trial will provide critically needed guidance for clinicians in a variety of health professions who prescribe and oversee treatment and prevention of OA-related complications. Given the prevalence and impact of OA and the widespread availability of this intervention, assessing the efficacy of optimal strength training has the potential for immediate and vital clinical impact. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01489462.

Effects of intensive diet and exercise on knee joint loads, inflammation, and clinical outcomes among overweight and obese adults with knee osteoarthritis: the IDEA randomized clinical trial.

IMPORTANCE: Knee osteoarthritis (OA), a common cause of chronic pain and disability, has biomechanical and inflammatory origins and is exacerbated by obesity. OBJECTIVE: To determine whether a ≥10% reduction in body weight induced by diet, with or without exercise, would improve mechanistic and clinical outcomes more than exercise alone. DESIGN, SETTING, AND PARTICIPANTS: Single-blind, 18-month, randomized clinical trial at Wake Forest University between July 2006 and April 2011. The diet and exercise interventions were center-based with options for the exercise groups to transition to a home-based program. Participants were 454 overweight and obese older community-dwelling adults (age ≥55 years with body mass index of 27-41) with pain and radiographic knee OA. INTERVENTIONS: Intensive diet-induced weight loss plus exercise, intensive diet-induced weight loss, or exercise. MAIN OUTCOMES AND MEASURES: Mechanistic primary outcomes: knee joint compressive force and plasma IL-6 levels; secondary clinical outcomes: self-reported pain (range, 0-20), function (range, 0-68), mobility, and health-related quality of life (range, 0-100). RESULTS: Three hundred ninety-nine participants (88%) completed the study. Mean weight loss for diet + exercise participants was 10.6 kg (11.4%); for the diet group, 8.9 kg (9.5%); and for the exercise group, 1.8 kg (2.0%). After 18 months, knee compressive forces were lower in diet participants (mean, 2487 N; 95% CI, 2393 to 2581) compared with exercise participants (2687 N; 95% CI, 2590 to 2784, pairwise difference [Δ](exercise vs diet )= 200 N; 95% CI, 55 to 345; P = .007). Concentrations of IL-6 were lower in diet + exercise (2.7 pg/mL; 95% CI, 2.5 to 3.0) and diet participants (2.7 pg/mL; 95% CI, 2.4 to 3.0) compared with exercise participants (3.1 pg/mL; 95% CI, 2.9 to 3.4; Δ(exercise vs diet + exercise) = 0.39 pg/mL; 95% CI, -0.03 to 0.81; P = .007; Δ(exercise vs diet )= 0.43 pg/mL; 95% CI, 0.01 to 0.85, P = .006). The diet + exercise group had less pain (3.6; 95% CI, 3.2 to 4.1) and better function (14.1; 95% CI, 12.6 to 15.6) than both the diet group (4.8; 95% CI, 4.3 to 5.2) and exercise group (4.7; 95% CI, 4.2 to 5.1, Δ(exercise vs diet + exercise) = 1.02; 95% CI, 0.33 to 1.71; P(pain) = .004; 18.4; 95% CI, 16.9 to 19.9; Δ(exercise vs diet + exercise), 4.29; 95% CI, 2.07 to 6.50; P(function )< .001). The diet + exercise group (44.7; 95% CI, 43.4 to 46.0) also had better physical health-related quality of life scores than the exercise group (41.9; 95% CI, 40.5 to 43.2; Δ(exercise vs diet + exercise) = -2.81; 95% CI, -4.76 to -0.86; P = .005). CONCLUSIONS AND RELEVANCE: Among overweight and obese adults with knee OA, after 18 months, participants in the diet + exercise and diet groups had more weight loss and greater reductions in IL-6 levels than those in the exercise group; those in the diet group had greater reductions in knee compressive force than those in the exercise group. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00381290.