Weight management and physical activity throughout the cancer care continuum.

Mounting evidence suggests that weight management and physical activity (PA) improve overall health and well being, and reduce the risk of morbidity and mortality among cancer survivors. Although many opportunities exist to include weight management and PA in routine cancer care, several barriers remain. This review summarizes key topics addressed in a recent National Academies of Science, Engineering, and Medicine workshop entitled, "Incorporating Weight Management and Physical Activity Throughout the Cancer Care Continuum." Discussions related to body weight and PA among cancer survivors included: 1) current knowledge and gaps related to health outcomes; 2) effective intervention approaches; 3) addressing the needs of diverse populations of cancer survivors; 4) opportunities and challenges of workforce, care coordination, and technologies for program implementation; 5) models of care; and 6) program coverage. While more discoveries are still needed for the provision of optimal weight-management and PA programs for cancer survivors, obesity and inactivity currently jeopardize their overall health and quality of life. Actionable future directions are presented for research; practice and policy changes required to assure the availability of effective, affordable, and feasible weight management; and PA services for all cancer survivors as a part of their routine cancer care. CA Cancer J Clin 2018;68:64-89. © 2017 American Cancer Society.

Mitigating skeletal muscle wasting in unloading and augmenting subsequent recovery.

Skeletal muscle wasting is the hallmark pathophysiological adaptation to unloading or disuse that demonstrates the dependency on frequent mechanical stimulation (e.g. muscle activation and subsequent loading) for homeostasis of normally load-bearing muscles. In the absence of mitigation strategies, no mammalian organism is resistant to muscle atrophy driven by unloading. Given the profound impact of unloading-induced muscle wasting on physical capacity, metabolic health and immune function; mitigation strategies during unloading and/or augmentation approaches during recovery have broad healthcare implications in settings of bed-bound hospitalization, cast immobilization and spaceflight. This topical review aims to: (1) provide a succinct, state-of-the-field summary of seminal and recent findings regarding the mechanisms of unloading-induced skeletal muscle wasting; (2) discuss unsuccessful vs. promising mitigation and recovery augmentation strategies; and (3) identify knowledge gaps ripe for future research. We focus on the rapid muscle atrophy driven by relatively short-term mechanical unloading/disuse, which is in many ways mechanistically distinct from both hypermetabolic muscle wasting and denervation-induced muscle atrophy. By restricting this discussion to mechanical unloading during which all components of the nervous system remain intact (e.g. without denervation models), mechanical loading requiring motor and sensory neural circuits in muscle remain viable targets for both mitigation and recovery augmentation. We emphasize findings in humans with comparative discussions of studies in rodents which enable elaboration of key mechanisms. We also discuss what is currently known about the effects of age and sex as biological factors, and both are highlighted as knowledge gaps and novel future directions due to limited research.

Ketone monoester attenuates oxygen desaturation during weighted ruck exercise under acute hypoxic exposure but does not impact cognitive performance.

Acute ingestion of exogenous ketone supplements in the form of a (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (R-BD R-ßHB) ketone monoester (KME) can attenuate declines in oxygen availability during hypoxic exposure and might impact cognitive performance at rest and in response to moderate-intensity exercise. In a single-blind randomized crossover design, 16 males performed assessments of cognitive performance before and during hypoxic exposure with moderate exercise [2 × 20 min weighted ruck (∼22 kg) at 3.2 km/h at 10% incline] in a normobaric altitude chamber (4572 m, 11.8% O2). The R-BD R-ßHB KME (573 mg/kg) or a calorie- and taste-matched placebo (∼50 g maltodextrin) were co-ingested with 40 g of dextrose before exposure to hypoxia. The R-ßHB concentrations were rapidly elevated and sustained (>3 mM; P < 0.001) by KME. The decline in oxygen saturation during hypoxic exposure was attenuated in KME conditions by 2.4%-4.2% (P < 0.05) compared with placebo. Outcomes of cognitive performance tasks, in the form of the Defense Automated Neurobehavioral Assessment (DANA) code substitution task, the Stroop color and word task, and a shooting simulation, did not differ between trials before and during hypoxic exposure. These data suggest that the acute exogenous ketosis induced by KME ingestion can attenuate declining blood oxygen saturation during acute hypoxic exposure both at rest and during moderate-intensity exercise, but this did not translate into differences in cognitive performance before or after exercise in the conditions investigated.

Ketone monoester attenuates declines in cognitive performance and oxygen saturation during acute severe hypoxic exposure under resting conditions.

Exogenous ketone supplements are a potential augmentation strategy for cognitive resilience during acute hypoxic exposure due to their capacity to attenuate the decline in oxygen (O2) availability, and by providing an alternative substrate for cerebral metabolism. Utilizing a single-blind randomized crossover design, 16 male military personnel (age, 25.3 ± 2.4 year, body mass, 86.2 ± 9.3 kg) performed tests of cognitive performance at rest in three environments: room air (baseline), normoxia (20 min; 0 m; 20.9% O2) and hypoxia (20 min; 6096 m, 9.7% O2) using a reduced O2 breathing device (ROBD). (R)-3-Hydroxybutyl (R)-3-hydroxybutyrate (R-BD R-ßHB) ketone monoester (KME; 650 mg/kg, split dose given at 30 min prior to each exposure) or taste-matched placebo (PLA) was ingested prior to normoxia and hypoxic exposure. Blood R-ßHB and glucose concentrations, cognitive performance and O2 saturation ( S p O 2 ${{S}_{{\mathrm{p}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$ ) were collected throughout. KME ingestion increased blood R-ßHB concentration, which was rapid and sustained (>4 mM 30 min post; P < 0.001) and accompanied by lower blood glucose concentration (∼20 mg/dL; P < 0.01) compared to PLA. Declines in cognitive performance during hypoxic exposure, assessed as cognitive efficiency during a Defense Automated Neurobehavioral Assessment (DANA) code substitution task, were attenuated with KME leading to 6.8 (95% CL: 1.0, 12.6) more correct responses per minute compared to PLA (P = 0.018). The decline in S p O 2 ${{S}_{{\mathrm{p}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$ during hypoxic exposure was attenuated (6.40% S p O 2 ${{S}_{{\mathrm{p}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$ ; 95% CL: 0.04, 12.75; P = 0.049) in KME compared to PLA (KME, 76.8 ± 6.4% S p O 2 ${{S}_{{\mathrm{p}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$ ; PLA, 70.4 ± 7.4% S p O 2 ${{S}_{{\mathrm{p}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$ ). Acute ingestion of KME attenuated the decline in cognitive performance during acute severe hypoxic exposure, which coincided with attenuation of declines in O2 saturation.

Dynamic transcriptomic responses to divergent acute exercise stimuli in young adults.

Acute exercise elicits dynamic transcriptional changes that, when repeated, form the fundamental basis of health, resilience, and performance adaptations. While moderate-intensity endurance training combined with conventional resistance training (traditional, TRAD) is often prescribed and recommended by public health guidance, high-intensity training combining maximal-effort intervals with intensive, limited-rest resistance training is a time-efficient alternative that may be used tactically (HITT) to confer similar benefits. Mechanisms of action of these distinct stimuli are incompletely characterized and have not been directly compared. We assessed transcriptome-wide responses in skeletal muscle and circulating extracellular vesicles (EVs) to a single exercise bout in young adults randomized to TRAD (n = 21, 12 M/9 F, 22 ± 3 yr) or HITT (n = 19, 11 M/8 F, 22 ± 2 yr). Next-generation sequencing captured small, long, and circular RNA in muscle and EVs. Analysis identified differentially expressed transcripts (|log2FC|>1, FDR ≤ 0.05) immediately (h0, EVs only), h3, and h24 postexercise within and between exercise protocols. In aaddition, all apparently responsive transcripts (FDR < 0.2) underwent singular value decomposition to summarize data structures into latent variables (LVs) to deconvolve molecular expression circuits and interregulatory relationships. LVs were compared across time and exercise protocol. TRAD, a longer but less intense stimulus, generally elicited a stronger transcriptional response than HITT, but considerable overlap and key differences existed. Findings reveal shared and unique molecular responses to the exercise stimuli and lay groundwork toward establishing relationships between protein-coding genes and lesser-understood transcripts that serve regulatory roles following exercise. Future work should advance the understanding of these circuits and whether they repeat in other populations or following other types of exercise/stress.NEW & NOTEWORTHY We examined small and long transcriptomics in skeletal muscle and serum-derived extracellular vesicles before and after a single exposure to traditional combined exercise (TRAD) and high-intensity tactical training (HITT). Across 40 young adults, we found more consistent protein-coding gene responses to TRAD, whereas HITT elicited differential expression of microRNA enriched in brain regions. Follow-up analysis revealed relationships and temporal dynamics across transcript networks, highlighting potential avenues for research into mechanisms of exercise response and adaptation.

SARS-CoV-2 Transmission among Marine Recruits during Quarantine.

BACKGROUND: The efficacy of public health measures to control the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has not been well studied in young adults. METHODS: We investigated SARS-CoV-2 infections among U.S. Marine Corps recruits who underwent a 2-week quarantine at home followed by a second supervised 2-week quarantine at a closed college campus that involved mask wearing, social distancing, and daily temperature and symptom monitoring. Study volunteers were tested for SARS-CoV-2 by means of quantitative polymerase-chain-reaction (qPCR) assay of nares swab specimens obtained between the time of arrival and the second day of supervised quarantine and on days 7 and 14. Recruits who did not volunteer for the study underwent qPCR testing only on day 14, at the end of the quarantine period. We performed phylogenetic analysis of viral genomes obtained from infected study volunteers to identify clusters and to assess the epidemiologic features of infections. RESULTS: A total of 1848 recruits volunteered to participate in the study; within 2 days after arrival on campus, 16 (0.9%) tested positive for SARS-CoV-2, 15 of whom were asymptomatic. An additional 35 participants (1.9%) tested positive on day 7 or on day 14. Five of the 51 participants (9.8%) who tested positive at any time had symptoms in the week before a positive qPCR test. Of the recruits who declined to participate in the study, 26 (1.7%) of the 1554 recruits with available qPCR results tested positive on day 14. No SARS-CoV-2 infections were identified through clinical qPCR testing performed as a result of daily symptom monitoring. Analysis of 36 SARS-CoV-2 genomes obtained from 32 participants revealed six transmission clusters among 18 participants. Epidemiologic analysis supported multiple local transmission events, including transmission between roommates and among recruits within the same platoon. CONCLUSIONS: Among Marine Corps recruits, approximately 2% who had previously had negative results for SARS-CoV-2 at the beginning of supervised quarantine, and less than 2% of recruits with unknown previous status, tested positive by day 14. Most recruits who tested positive were asymptomatic, and no infections were detected through daily symptom monitoring. Transmission clusters occurred within platoons. (Funded by the Defense Health Agency and others.).

A muscle cell-macrophage axis involving matrix metalloproteinase 14 facilitates extracellular matrix remodeling with mechanical loading.

The extracellular matrix (ECM) in skeletal muscle plays an integral role in tissue development, structural support, and force transmission. For successful adaptation to mechanical loading, remodeling processes must occur. In a large cohort of older adults, transcriptomics revealed that genes involved in ECM remodeling, including matrix metalloproteinase 14 (MMP14), were the most upregulated following 14 weeks of progressive resistance exercise training (PRT). Using single-cell RNA-seq, we identified macrophages as a source of Mmp14 in muscle following a hypertrophic exercise stimulus in mice. In vitro contractile activity in myotubes revealed that the gene encoding cytokine leukemia inhibitory factor (LIF) is robustly upregulated and can stimulate Mmp14 expression in macrophages. Functional experiments confirmed that modulation of this muscle cell-macrophage axis facilitated Type I collagen turnover. Finally, changes in LIF expression were significantly correlated with MMP14 expression in humans following 14 weeks of PRT. Our experiments reveal a mechanism whereby muscle fibers influence macrophage behavior to promote ECM remodeling in response to mechanical loading.

Muscle transcriptomic circuits linked to periarticular physiology in end-stage osteoarthritis.

The ability of individuals with end-stage osteoarthritis (OA) to functionally recover from total joint arthroplasty is highly inconsistent. The molecular mechanisms driving this heterogeneity have yet to be elucidated. Furthermore, OA disproportionately impacts females, suggesting a need for identifying female-specific therapeutic targets. We profiled the skeletal muscle transcriptome in females with end-stage OA (n = 20) undergoing total knee or hip arthroplasty using RNA-Seq. Single-gene differential expression (DE) analyses tested for DE genes between skeletal muscle overlaying the surgical (SX) joint and muscle from the contralateral (CTRL) leg. Network analyses were performed using Pathway-Level Information ExtractoR (PLIER) to summarize genes into latent variables (LVs), i.e., gene circuits, and link them to biological pathways. LV differences in SX versus CTRL muscle and across sources of muscle tissue (vastus medialis, vastus lateralis, or tensor fascia latae) were determined with ANOVA. Linear models tested for associations between LVs and muscle phenotype on the SX side (inflammation, function, and integrity). DE analysis revealed 360 DE genes (|Log2 fold-difference| ≥ 1, FDR ≤ 0.05) between the SX and CTRL limbs, many associated with inflammation and lipid metabolism. PLIER analyses revealed circuits associated with protein degradation and fibro-adipogenic cell gene expression. Muscle inflammation and function were linked to an LV associated with endothelial cell gene expression highlighting a potential regulatory role of endothelial cells within skeletal muscle. These findings may provide insight into potential therapeutic targets to improve OA rehabilitation before and/or following total joint replacement.

Skeletal muscle transcriptome response to a bout of endurance exercise in physically active and sedentary older adults.

Age-related declines in cardiorespiratory fitness and physical function are mitigated by regular endurance exercise in older adults. This may be due, in part, to changes in the transcriptional program of skeletal muscle following repeated bouts of exercise. However, the impact of chronic exercise training on the transcriptional response to an acute bout of endurance exercise has not been clearly determined. Here, we characterized baseline differences in muscle transcriptome and exercise-induced response in older adults who were active/endurance trained or sedentary. RNA-sequencing was performed on vastus lateralis biopsy specimens obtained before, immediately after, and 3 h following a bout of endurance exercise (40 min of cycling at 60%-70% of heart rate reserve). Using a recently developed bioinformatics approach, we found that transcript signatures related to type I myofibers, mitochondria, and endothelial cells were higher in active/endurance-trained adults and were associated with key phenotypic features including V̇o2peak, ATPmax, and muscle fiber proportion. Immune cell signatures were elevated in the sedentary group and linked to visceral and intermuscular adipose tissue mass. Following acute exercise, we observed distinct temporal transcriptional signatures that were largely similar among groups. Enrichment analysis revealed catabolic processes were uniquely enriched in the sedentary group at the 3-h postexercise timepoint. In summary, this study revealed key transcriptional signatures that distinguished active and sedentary adults, which were associated with difference in oxidative capacity and depot-specific adiposity. The acute response signatures were consistent with beneficial effects of endurance exercise to improve muscle health in older adults irrespective of exercise history and adiposity.NEW & NOTEWORTHY Muscle transcript signatures associated with oxidative capacity and immune cells underlie important phenotypic and clinical characteristics of older adults who are endurance trained or sedentary. Despite divergent phenotypes, the temporal transcriptional signatures in response to an acute bout of endurance exercise were largely similar among groups. These data provide new insight into the transcriptional programs of aging muscle and the beneficial effects of endurance exercise to promote healthy aging in older adults.

Smad8 Is Increased in Duchenne Muscular Dystrophy and Suppresses miR-1, miR-133a, and miR-133b.

Duchenne muscular dystrophy (DMD) is an X-linked recessive disease characterized by skeletal muscle instability, progressive muscle wasting, and fibrosis. A major driver of DMD pathology stems from aberrant upregulation of transforming growth factor ß (TGFß) signaling. In this report, we investigated the major transducers of TGFß signaling, i.e., receptor Smads (R-Smads), in DMD patient skeletal muscle and observed a 48-fold increase in Smad8 mRNA. Smad1, Smad2, Smad3, and Smad5 mRNA were only minimally increased. A similar pattern was observed in the muscle from the mdx5cv mouse. Western blot analysis showed upregulation of phosphorylated Smad1, Smad5, and Smad8 compared to total Smad indicating activation of this pathway. In parallel, we observed a profound diminishment of muscle-enriched microRNAs (myomiRs): miR-1, miR-133a, and miR-133b. The pattern of Smad8 induction and myomiR suppression was recapitulated in C2C12 muscle cells after stimulation with bone morphogenetic protein 4 (BMP4), a signaling factor that we found upregulated in DMD muscle. Silencing Smad8 in C2C12 myoblasts derepressed myomiRs and promoted myoblast differentiation; there was also a concomitant upregulation of myogenic regulatory factors (myogenin and myocyte enhancer factor 2D) and suppression of a pro-inflammatory cytokine (interleukin-6). Our data suggest that Smad8 is a negative regulator of miR-1, miR-133a, and miR-133b in muscle cells and that the BMP4-Smad8 axis is a driver of dystrophic pathology in DMD.

Mechanisms of exercise as a preventative measure to muscle wasting.

Skeletal muscle is the most abundant tissue in healthy individuals and it has important roles in health beyond voluntary movement. The overall mass and energy requirements of skeletal muscle require it to be metabolically active and flexible to multiple energy substrates. The tissue has evolved to be largely load dependent and it readily adapts in a number of positive ways to repetitive overload, such as various forms of exercise training. However, unloading from extended bed rest and/or metabolic derangements in response to trauma, acute illness, or severe pathology, commonly results in rapid muscle wasting. Decline in muscle mass contributes to multimorbidity, reduces function, and exerts a substantial, negative impact on the quality of life. The principal mechanisms controlling muscle mass have been well described and these cellular processes are intricately regulated by exercise. Accordingly, exercise has shown great promise and efficacy in preventing or slowing muscle wasting through changes in molecular physiology, organelle function, cell signaling pathways, and epigenetic regulation. In this review, we focus on the role of exercise in altering the molecular landscape of skeletal muscle in a manner that improves or maintains its health and function in the presence of unloading or disease.epigenetics; exercise; muscle wasting; resistance training; skeletal muscle.

Muscle transcriptional networks linked to resistance exercise training hypertrophic response heterogeneity.

The skeletal muscle hypertrophic response to resistance exercise training (RT) is highly variable across individuals. The molecular underpinnings of this heterogeneity are unclear. This study investigated transcriptional networks linked to RT-induced muscle hypertrophy, classified as 1) predictive of hypertrophy, 2) responsive to RT independent of muscle hypertrophy, or 3) plastic with hypertrophy. Older adults (n = 31, 18 F/13 M, 70 ± 4 yr) underwent 14-wk RT (3 days/wk, alternating high-low-high intensity). Muscle hypertrophy was assessed by pre- to post-RT change in mid-thigh muscle cross-sectional area (CSA) [computed tomography (CT), primary outcome] and thigh lean mass [dual-energy X-ray absorptiometry (DXA), secondary outcome]. Transcriptome-wide poly-A RNA-seq was performed on vastus lateralis tissue collected pre- (n = 31) and post-RT (n = 22). Prediction networks (using only baseline RNA-seq) were identified by weighted gene correlation network analysis (WGCNA). To identify Plasticity networks, WGCNA change indices for paired samples were calculated and correlated to changes in muscle size outcomes. Pathway-level information extractor (PLIER) was applied to identify Response networks and link genes to biological annotation. Prediction networks (n = 6) confirmed transcripts previously connected to resistance/aerobic training adaptations in the MetaMEx database while revealing novel member genes that should fuel future research to understand the influence of baseline muscle gene expression on hypertrophy. Response networks (n = 6) indicated RT-induced increase in aerobic metabolism and reduced expression of genes associated with spliceosome biology and type-I myofibers. A single exploratory Plasticity network was identified. Findings support that interindividual differences in baseline gene expression may contribute more than RT-induced changes in gene networks to muscle hypertrophic response heterogeneity. Code/Data: https://github.com/kallavin/MASTERS_manuscript/tree/master.

In vivo analysis of γH2AX+ cells in skeletal muscle from aged and obese humans.

Over the past 20 years, various identifiers of cellular senescence have been used to quantify the abundance of these cells in different tissues. These include classic markers such as p16, senescence-associated ß-gal, and γH2AX, in addition to more recent markers (Sudan Black B and HMGB1). In vivo data on the usefulness of these markers in skeletal muscle are very limited and inconsistent. In the present study, we attempted to identify senescent cells in frozen human skeletal muscle biopsies using these markers to determine the effects of age and obesity on senescent cell burden; however, we were only able to assess the abundance of DNA-damaged nuclei using γH2AX immunohistochemistry. The abundance of γH2AX+ cells, including satellite cells, was not higher in muscle from old compared to young individuals; however, γH2AX+ cells were higher with obesity. Additionally, terminally differentiated, postmitotic myofiber nuclei from obese individuals had elevated γH2AX abundance compared to muscle from lean individuals. Analyses of gene expression support the conclusion that the elevated DNA damage and the senescence-associated secretory phenotype are preferentially associated with obesity in skeletal muscle. These data implicate obesity as a larger contributor to DNA damage in skeletal muscle than aging; however, more sensitive senescence markers for human skeletal muscle are needed to determine if these cells are in fact senescent.

Potential role for age as a modulator of oral nitrate reductase activity.

Reduction of salivary nitrate to nitrite by oral nitrate reductase (NR) expressing bacteria has emerged as an integral pathway in regulating nitric oxide (NO) homeostasis and signaling. The oral microbiome is critical for this pathway. Variations in this pathway may underlie variable responses in the magnitude by which dietary or therapeutic nitrate modulates NO-signaling. The relationships between oral microbes and NR activity, and the factors that affect this relationship remain unclear however. Using a cross-sectional study design, the objective of this study was to determine the relationships between oral microbes and oral NR activity using a protocol that directly measures initial NR activity. Tongue swabs were collected from 28 subjects ranging in age from 21 to 73y. Initial NR activity showed a bell-shaped dependence with age, with activity peaking at ~40-50y and being lower but similar between younger (20-30y) and older (51-73) individuals. Microbiome relative abundance and diversity analyses, using 16s sequencing, demonstrated differences across age and identified both NR expressing and non-expressing bacteria in modulating initial NR activity. Finally, initial NR activity was measured in 3mo and 13mo old C57BL/6J mice. No differences in bacterial number were observed. However initial NR activity was significantly (80%) lower in 13mo old mice. Collectively, these data suggest that age is a variable in NR activity and may modulate responsiveness to dietary nitrate.

The Importance of Resistance Exercise Training to Combat Neuromuscular Aging.

Older adults undergoing age-related decrements in muscle health can benefit substantially from resistance exercise training, a potent stimulus for whole muscle and myofiber hypertrophy, neuromuscular performance gains, and improved functional mobility. With the use of advancing technologies, research continues to elucidate the mechanisms of and heterogeneity in adaptations to resistance exercise training beyond differences in exercise prescription. This review highlights the current knowledge in these areas and emphasizes knowledge gaps that require future attention of the field.

Randomized, Controlled Trial of Exercise on Objective and Subjective Sleep in Parkinson's Disease.

BACKGROUND: Sleep dysfunction is common and disabling in persons with Parkinson's Disease (PD). Exercise improves motor symptoms and subjective sleep quality in PD, but there are no published studies evaluating the impact of exercise on objective sleep outcomes. The goal of this study was to to determine if high-intensity exercise rehabilitation combining resistance training and body-weight interval training, compared with a sleep hygiene control improved objective sleep outcomes in PD. METHODS: Persons with PD (Hoehn & Yahr stages 2-3; aged ≥45 years, not in a regular exercise program) were randomized to exercise (supervised 3 times a week for 16 weeks; n = 27) or a sleep hygiene, no-exercise control (in-person discussion and monthly phone calls; n = 28). Participants underwent polysomnography at baseline and post-intervention. Change in sleep efficiency was the primary outcome, measured from baseline to post-intervention. Intervention effects were evaluated with general linear models with measurement of group × time interaction. As secondary outcomes, we evaluated changes in other aspects of sleep architecture and compared the effects of acute and chronic training on objective sleep outcomes. RESULTS: The exercise group showed significant improvement in sleep efficiency compared with the sleep hygiene group (group × time interaction: F = 16.0, P < 0.001, d = 1.08). Other parameters of sleep architecture also improved in exercise compared with sleep hygiene, including total sleep time, wake after sleep onset, and slow-wave sleep. Chronic but not acute exercise improved sleep efficiency compared with baseline. CONCLUSIONS: High-intensity exercise rehabilitation improves objective sleep outcomes in PD. Exercise is an effective nonpharmacological intervention to improve this disabling nonmotor symptom in PD. © 2020 International Parkinson and Movement Disorder Society.

Step-rate threshold for physical activity intensity in Parkinson's disease.

OBJECTIVES: To examine the relationship between step-rate and energy expenditure during treadmill walking in persons with PD and then further develop a step-rate cut-point for moderate-to-vigorous physical activity (MVPA) for persons with PD. MATERIALS AND METHODS: The sample consisted of 30 persons with mild-to-moderate PD and 30 controls matched by age and sex. Participants performed a 6-minute bout of over-ground walking at comfortable speed, and then completed three, 6-minute bouts of treadmill walking at 13.4 m/min slower, comfortable, and 13.4 m/min faster than comfortable speeds. The three treadmill speeds were based on the initial over-ground walking speed. The total number of steps per treadmill walking bout was recorded using a hand-tally counter, and energy expenditure was measured using a portable, indirect spirometry system. RESULTS: The results indicated a strong association between step-rate and energy expenditure for persons with PD (R2  = .92) and controls (R2  = .92). The analyses further indicated a steeper slope of the association for persons with PD compared with controls (t(58) = -1.87, P < .05), resulting in a lower step-rate threshold (t(58) = 2.19, P < .05) for persons with PD (~80 steps·per minutes) than controls (~93 steps·per minutes). CONCLUSION: Collectively, these results support the application of this disease-specific step-rate threshold for MVPA among persons with PD. This has important implications for physical activity promotion, prescription, and monitoring using accelerometers and pedometers for persons with PD to manage health and symptoms of PD.

Comparison of Resistance-Based Walking Cardiorespiratory Test to the Bruce Protocol.

Hurt, CP, Bamman, M, Naidu, A, and Brown, DA. Comparison of resistance-based walking cardiorespiratory test to the Bruce Protocol. J Strength Cond Res 34(12): 3569-3576, 2020-Cardiorespiratory fitness is assessed through graded exercise tests that determine the maximum amount of sustained mechanical work that an individual can perform while also providing health- and fitness-related information. This article describes a novel method to perform graded exercise tests that use posteriorly directed resistive forces. The purpose of this investigation was to validate a novel resistance-based test (RBT) in comparison with a traditional speed- and incline-based test (SIBT) in a cohort of nonimpaired individuals. Twenty nonimpaired individuals, 8 men and 20 women age 28.4 ± 9.6, range 20-54 years old performed 2 maximal exercise tests. The SIBT used the Bruce Protocol and increased treadmill incline and speed every 3 minutes. The RBT used a robotic device interfaced with the treadmill that provided specified horizontal resistive forces at the center of mass calculated to match each Bruce Protocol stage while individuals walked at 1.1 m·s. Subjects obtained ∼3% higher maximum V[Combining Dot Above]O2 measure using the speed- and incline-based method (dependent t-test p = 0.08). V[Combining Dot Above]O2peaks between tests were strongly correlated (r = 0.93, p < 0.001). Peak values of secondary physiologic measures (i.e., max heart rate and respiratory exchange ratio) were within 3% between tests. We found a significant linear relationship between mass-specific work rate and measured V[Combining Dot Above]O2 stage by stage for both tests, but no significant difference between each linear fit (p = 0.84). These data suggest that horizontal resistive forces, while walking on a treadmill, can be used to increase aerobic effort in a way that closely simulates work rates of the Bruce Protocol.

A pilot study of combined endurance and resistance exercise rehabilitation for verbal memory and functional connectivity improvement in epilepsy.

Memory impairment is common in persons with epilepsy (PWE), and exercise may be a strategy for its improvement. In this pilot study, we hypothesized that exercise rehabilitation would improve physical fitness and verbal memory and induce changes in brain networks involved in memory processes. We examined the effects of combined endurance and resistance exercise rehabilitation on memory and resting state functional connectivity (rsFC). Participants were randomized to exercise (PWE-E) or control (PWE-noE). The exercise intervention consisted of 18 supervised sessions on nonconsecutive days over 6 weeks. Before and after the intervention period, both groups completed self-report assessments (Short Form-36 (SF-36), Baecke Questionnaire (BQ) of habitual physical activity, and Profile of Mood States (POMS)), cognitive testing (California Verbal Learning Test-II (CVLT-II)), and magnetic resonance imaging (MRI); PWE-E also completed exercise performance tests. After completing the study, PWE-noE were offered cross-over to the exercise arm. There were no differences in baseline demographic, clinical, or assessment variables between 8 PWE-noE and 9 PWE-E. Persons with epilepsy that participated in exercise intervention increased maximum voluntary strength (all strength tests p < 0.05) and exhibited nonsignificant improvement in cardiorespiratory fitness (p = 0.15). Groups did not show significant changes in quality of life (QOL) or habitual physical activity between visits. However, there was an effect of visit on POMS total mood disturbance (TMD) measure showing improvement from baseline to visit 2 (p = 0.023). There were significant group by visit interactions on CVLT-II learning score (p = 0.044) and total recognition discriminability (d') (p = 0.007). Persons with epilepsy that participated in exercise intervention had significant reductions in paracingulate rsFC with the anterior cingulate and increases in rsFC for the cerebellum, thalamus, posterior cingulate cortex (PCC), and left and right inferior parietal lobule (IPL) (corrected p < 0.05). Change in CVLT-II learning score was associated with rsFC changes for the paracingulate cortex (rS = -0.67; p = 0.0033), left IPL (rS = 0.70; p = 0.0019), and right IPL (rS = 0.71; p = 0.0015) while change in d' was associated with change in cerebellum rsFC to angular/middle occipital gyrus (rS = 0.68; p = 0.0025). Our conclusion is that exercise rehabilitation may facilitate verbal memory improvement and brain network functional connectivity changes in PWE and that improved memory performance is associated with changes in rsFC. A larger randomized controlled trial of exercise rehabilitation for cognitive improvement in PWE is warranted.

Quantification and characterization of grouped type I myofibers in human aging.

INTRODUCTION: Myofiber type grouping is a histological hallmark of age-related motor unit remodeling. Despite the accepted concept that denervation-reinnervation events lead to myofiber type grouping, the completeness of those conversions remains unknown. METHODS: Type I myofiber grouping was assessed in vastus lateralis biopsies from Young (26 ± 4 years; n = 27) and Older (66 ± 4 years; n = 91) adults. Grouped and ungrouped type I myofibers were evaluated for phenotypic differences. RESULTS: Higher type I grouping in Older versus Young was driven by more myofibers per group (i.e., larger group size) (P < 0.05). In Older only, grouped type I myofibers displayed larger cross-sectional area, more myonuclei, lower capillary supply, and more sarco(endo)plasmic reticulum calcium ATPase I (SERCA I) expression (P < 0.05) than ungrouped type I myofibers. DISCUSSION: Grouped type I myofibers retain type II characteristics suggesting that conversion during denervation-reinnervation events is either progressive or incomplete. Muscle Nerve 57: E52-E59, 2018.