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Background: Ambulation using standard axillary crutches (SACs) is associated with increased energy expenditure (EE) and decreased ability to perform activities of daily living (ADLs). Using a hands‐free crutch (HFC) displays potential for easier completion of ADLs and reduction in energy requirements. Objectives: To determine if a HFC elicits lower EE and heart rate (HR), improvement in performance of ADLs, and decreased rating of perceived exertion (RPE) compared to common ambulatory devices. Design: A randomized crossover‐controlled trial. Setting: University community. Participants: Twenty healthy college students. Main Outcome Measures: Participants completed a 6‐minute walk test at 50 m/min, an ADLs course, and a two‐flight stair climb with SACs, HFC, knee scooter (KS), and unassisted ambulation (UA). The order of trial conditions was randomized. EE, HR, time to complete ADLs course and stair climb, and RPE during each condition were obtained. One‐way analyses of variance were performed to compare EE, HR response, and RPE between the assistive devices and UA. Results: In all outcomes UA resulted in lower EE, HR, and RPE compared to all the assistive devices (p <.05). For the ADLs course, EE was the same for the three assistive devices, whereas HR was significantly lower for HFC compared to SACs and KS (p <.05). RPE for HFC and KS was lower than SACs (p <.05). For the 6MWT, each device significantly differed from the other devices for EE, HR, and RPE, with KS eliciting the lowest values, followed by HFC. For the stair climbing task, HFC elicited lower EE, HR, and RPE than SACs. Fourteen participants indicated their overall preference for HFCs. Conclusions: In individuals prescribed weight‐bearing restrictions, using a HFC may offer an easier and more preferred alternative to more commonly used SACs during ambulation, stair climbing, and other ADLs. [ABSTRACT FROM AUTHOR]

Brown adipose tissue (BAT) plays an important role in mammalian thermoregulation. The component of BAT mitochondria that permits this function is the inner membrane carrier protein uncoupling protein 1 (UCP1). To the best of our knowledge, no studies have directly quantified UCP1 function in human BAT. Further, whether human and rodent BAT have comparable thermogenic function remains unknown. We employed high-resolution respirometry to determine the respiratory capacity, coupling control, and, most importantly, UCP1 function of human supraclavicular BAT and rodent interscapular BAT. Human BAT was sensitive to the purine nucleotide GDP, providing the first direct evidence that human BAT mitochondria have thermogenically functional UCP1. Further, our data demonstrate that human and rodent BAT have similar UCP1 function per mitochondrion. These data indicate that human and rodent BAT are qualitatively similar in terms of UCP1 function.

Apply It!: For individuals considering biking as an exercise or mode of active transport, encourage them to try an E-bike. Some cities provide E-bike kiosks for a small fee and some bicycle stores rent E-bikes. Sedentary individuals can use E-bikes as an entry into bicycle riding for health and fitness. The efforts may start low but they can increase effort over time. [ABSTRACT FROM AUTHOR]

Muscle inflammation and fibrosis underlie disuse‐related complications and may contribute to impaired muscle recovery in aging. Cellular senescence is an emerging link between inflammation, extracellular matrix (ECM) remodeling and poor muscle recovery after disuse. In rodents, metformin has been shown to prevent cellular senescence/senescent associated secretory phenotype (SASP), inflammation, and fibrosis making it a potentially practical therapeutic solution. Thus, the purpose of this study was to determine in older adults if metformin monotherapy during bed rest could reduce muscle fibrosis and cellular senescence/SASP during the re‐ambulation period. A two‐arm controlled trial was utilized in healthy male and female older adults (n = 20; BMI: <30, age: 60 years+) randomized into either placebo or metformin treatment during a two‐week run‐in and 5 days of bedrest followed by metformin withdrawal during 7 days of recovery. We found that metformin‐treated individuals had less type‐I myofiber atrophy during disuse, reduced pro‐inflammatory transcriptional profiles, and lower muscle collagen deposition during recovery. Collagen content and myofiber size corresponded to reduced whole muscle cellular senescence and SASP markers. Moreover, metformin treatment reduced primary muscle resident fibro‐adipogenic progenitors (FAPs) senescent markers and promoted a shift in fibroblast fate to be less myofibroblast‐like. Together, these results suggest that metformin pre‐treatment improved ECM remodeling after disuse in older adults by possibly altering cellular senescence and SASP in skeletal muscle and in FAPs. [ABSTRACT FROM AUTHOR]

Several factors affect muscle protein synthesis (MPS) in the postabsorptive state. Extreme physical inactivity (e.g., bedrest) may reduce basal MPS, whereas walking may augment basal MPS. We hypothesized that outpatients would have a higher postabsorptive MPS than inpatients. To test this hypothesis, we conducted a retrospective analysis. We compared 152 outpatient participants who arrived at the research site the morning of the MPS assessment with 350 Inpatient participants who had an overnight stay in the hospital unit before the MPS assessment the following morning. We used stable isotopic methods and collected vastus lateralis biopsies 2 to 3 h apart to assess mixed MPS. MPS was 12% higher (P < 0.05) for outpatients than inpatients. Within a subset of participants, we discovered that after instruction to limit activity, outpatients (n = 13) took 800 to 900 steps in the morning to arrive at the unit, seven times more steps than inpatients (n = 12). We concluded that an overnight stay in the hospital as an inpatient is characterized by reduced morning activity and causes a slight but significant reduction in MPS compared with participants studied as outpatients. Researchers should be aware of physical activity status when designing and interpreting MPS results. [ABSTRACT FROM AUTHOR]

We previously reported an increase in skeletal muscle protein synthesis during fasted and fed recovery from nonexhaustive aerobic exercise (Harber et al., 2010). The current study examined skeletal muscle intracellular signaling in the same subjects to further investigate mechanisms of skeletal muscle protein metabolism with and without feeding following aerobic exercise. Eight males (VO2peak: 52 ± 2 ml-1∙kg-1∙min-1) performed 60-min of cycle ergometry at 72 ± 1% VO2peak on two occasions in a counter-balanced design. Exercise trials differed only in the postexercise nutritional intervention: EX-FED (5kcal, 0.83g carbohydrate, 0.37g protein, 0.03g fat per kg body weight) and EX-FAST (noncaloric, isovolumic placebo) ingested immediately and one hour after exercise. Muscle biopsies were obtained from the vastus lateralis at rest (on a separate day) and two hours postexercise to assess intracellular signaling via western blotting of p70S6K1, eEF2, 4EBP1, AMPKα and p38 MAPK. p70S6K1 phosphorylation was elevated (p < .05) in EX-FED relative to REST and EX-FAST. eEF2, 4EBP1, AMPKα and p38 MAPK signaling were unaltered at 2h after exercise independent of feeding status when expressed as the ratio of phosphorylated to total protein normalized to actin. These data demonstrate that feeding after a nonexhaustive bout of aerobic exercise stimulates skeletal muscle p70S6K1 intracellular signaling favorable for promoting protein synthesis which may, as recent literature has suggested, better prepare the muscle for subsequent exercise bouts. These data provide further support into the role of feeding on mechanisms regulating muscle protein metabolism during recovery from aerobic exercise. [ABSTRACT FROM AUTHOR]