The microvasculature is critical in the control of blood flow. Aging and reduced physical activity may both decrease microvascular function. Purpose The primary aim was to evaluate the influence of age on microvascular function in adults with similar physical activity levels (PA). Secondary aims were to assess the reliability of muscle functional MRI in older adults and the relationship between physical activity and microvascular function in older adults. Methods Microvascular BOLD responses were measured in young adults (YA, n=12, 21±1 (±SD) years old, PA=239±73×103 counts/day) and older adults (OA, n=12, 64±4 years old, PA=203±48×103 counts/day). Functional MR images (3T, echo planar blood-oxygen-level dependent (BOLD)), of the leg were acquired following brief (1s) maximal voluntary isometric contractions. Test-retest reliability of BOLD responses and the Pearson correlation between peak BOLD and PA was assessed in a group of older adults (OA-r) with a broad range of PA (66±5 years old, n=9, PA range = 54×103 count/day to 674×103 counts/day). Results Peak BOLD microvascular responses were reduced for OA compared to YA. OA peak BOLD was 27% lower in the soleus (OA: 3.3±0.8% vs. YA: 4.5±1.4% YA, p=0.017) and 40% lower in the anterior compartment (1.6±0.6% OA vs. 2.7±1.1% YA, p=0.006). Coefficient of variation was 8.6% and 11.8% for peak BOLD in the soleus and anterior compartment, respectively, with an intraclass correlation of 0.950 for both muscle regions. The correlation between peak BOLD and PA was r ≥ 0.715, p ≤ 0.030. Conclusions Aging was associated with reduced microvascular function in leg muscles, independent of physical activity. The findings also revealed good reliability for BOLD MRI in older adults for the soleus and anterior compartment muscles.

Background: Statin use is widely recognized for improving cardiovascular health, but questions remain on how statin use influences skeletal muscle, particularly mitochondrial function. Study objective, design and participants: The influence of statin therapy and exercise (EX) on aerobic capacity was determined. In Study1, skeletal muscle aerobic capacity was measured before and after 80 mg atorvastatin therapy. In Study2, aerobic capacity (skeletal muscle and whole body) was measured before and after a 12-week exercise randomized control trial in older adults (age = 67 ± 5 yrs.), a subset of which were on chronic low-moderate intensity statin therapy. Main outcome measures: Muscle oxidative capacity was determined from the phosphocreatine recovery rate constant ( k PCr) using 31 P Magnetic Resonance Spectroscopy. Whole body peak oxygen uptake (VO 2 peak) was measured during a graded exercise test with indirect calorimetry. Results: High dose statin therapy resulted in a 12% reduction in muscle oxidative capacity (pre = 1.34 ± 0.34 min −1 , post = 1.17 ± 0.25 min −1 , p = 0.004). Similarly, chronic low-moderate dose statin therapy was associated with lower muscle oxidative capacity at baseline (1.50 ± 0.35 min −1 ) compared to non-statin users (1.88 ± 0.047 min −1 , p = 0.019). Following EX, muscle oxidative capacity increased by 35–40% (statin: Pre: 1.39 ± 0.44 vs. Post: 1.88 ± 0.47 min −1 , no statin Pre: 1.86 ± 0.58 vs. Post: 2.58 ± 0.85 min −1 ) compared to control groups (Pre: 1.74 ± 0.27 vs Post: 1.75 ± 0.49 min −1 , p = 0.001). VO 2 peak increased by 11% for EX groups (Pre: 18.8 ± 2.8 vs. Post: 20.8 ± 3.0 ml·kg −1 ·min −1 ) following training compared to a small decline in controls (Pre: 21.8 ± 3.7 vs. Post: 20.8 ± 3.04 ml·kg −1 ·min −1 , p = 0.001). Conclusions: Statin therapy resulted in reduced muscle oxidative capacity. Aerobic exercise improved skeletal muscle oxidative capacity and whole-body aerobic capacity during statin therapy.

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These results first suggest that a sizable proportion of ED personnel may fail N95 fit testing while wearing an ENDS beneath the N95 mask for which they had been previously fitted. Although providers' subjective interest in use of ENDS increased, these results also demonstrate that use of an ENDS beneath an N95 respirator may not significantly increase exercise tolerance.