Peak exercise oxygen uptake and changes in renal function in patients after acute myocardial infarction.

BACKGROUND: The impact of exercise tolerance on renal function change after acute myocardial infarction (AMI) is not clear. OBJECTIVES: The present study aimed to elucidate the effect of peak exercise oxygen uptake (VO2) levels on longitudinal changes in renal function up to 1 year after onset of AMI. METHODS: This retrospective longitudinal study enrolled 198 AMI patients. Symptom-limited cardiopulmonary exercise testing was performed at completion of early Phase II cardiac rehabilitation, and peak VO2 levels were defined as the primary exposure factor. The estimated glomerular filtration rates (eGFRs) at baseline, 3 months, 6 months and 1 year were collected. Generalized estimating equation (GEE) models were used to test the longitudinal effect of peak VO2 levels on within-patient changes in eGFR. RESULTS: Patients were stratified into tertile groups (Low group, 12.3 ± 1.3 mL/kg/min; Mid group, 15.3 ± 0.7 mL/kg/min; and High group, 19.1 ± 2.3 mL/kg/min) according to peak VO2 levels. The slopes of eGFR over 1 year in the Low (p = 0.024) and Mid groups (p = 0.037) were lower compared to the High group. The Low group had a significantly higher odds ratio of experiencing rapid renal function decline than the High group (odds ratio, 2.87; p = 0.012). CONCLUSIONS: There was a significant effect of lower peak VO2 on rapid decline in renal function after AMI. Our findings suggest that the coexistence of exercise intolerance may be a novel risk factor for rapid decline in renal function after AMI.

Relationship between physical activity and bone mineral density loss after gastrectomy in gastric cancer patients.

PURPOSE: The prevention of osteoporosis is a particularly relevant issue for gastric cancer survivors. We investigated the relationship between postoperative physical activity and the change of bone mineral density (BMD) in patients with gastric cancer. METHODS: Patients who underwent radical gastrectomy for gastric cancer were enrolled in this single-center prospective cohort study. Physical activity was evaluated using the International Physical Activity Questionnaire Short Form at postoperative month (POM) 6 and patients were classified into high, middle, and low physical activity groups accordingly. The primary outcome was the change in BMD from baseline at POM 12, which was expressed as a percentage of the young adult mean (YAM). The YAM of the lumbar spine and femoral neck was measured by dual-energy X-ray absorptiometry. RESULTS: One hundred ten patients were enrolled in this study. The physical activity level at POM 6 was classified as high (n = 50; 45%), middle (n = 25; 23%), and low (n = 35; 32%). The mean decrease of YAM% was 5.1% in the lumbar spine and 4.2% in the femoral neck at POM 12. A multivariable-adjusted logistic regression model revealed that low physical activity at POM 6 was a significant risk factor for BMD loss at POM 12 (odds ratio, 3.76; 95% confidence interval, 1.48-9.55; p = 0.005). CONCLUSION: Low physical activity after gastrectomy is an independent risk factor for decreased BMD at POM 12. The introduction of exercise may prevent osteoporosis after the surgical treatment of gastric cancer.

Early Exercise after Intracerebral Hemorrhage Inhibits Inflammation and Promotes Neuroprotection in the Sensorimotor Cortex in Rats.

The present study examined the effect of early exercise on brain damage and recovery of motor function following intracerebral hemorrhage (ICH) in rats. Subjects were randomly assigned to no training after ICH (ICH), no training after sham surgery (SHAM), early treadmill exercise after ICH (ICH + ET), and late treadmill exercise after ICH (ICH + LT) groups. The ICH + ET and ICH + LT groups were trained for seven consecutive days starting on day 2 and day 9 after surgery, respectively. At post surgery day 16, the brain was surgically excised, and lesion volume, cortical thickness, neuronal number, dendritic length, and dendritic complexity were analyzed. Expression levels of IL-1b, TGF-b1, and IGF-1 mRNAs in ipsilateral sensorimotor cortex were measured by RT-PCR. The recovery of motor function in the ICH + ET group was the most accelerated. Cortical thickness and neuronal number were significantly higher in the ICH + ET group than the ICH and ICH + LT groups. The length and complexity of dendrites were also significantly greater in the ICH + ET group compared with the ICH and ICH + LT groups. Expression of IL-1b mRNA was significantly lower in the ICH + ET group than that in the ICH group. Collectively, these results suggest that early treadmill exercise after ICH promotes recovery of sensorimotor function by preventing neuronal death and ensuing cortical atrophy and by preserving dendritic structure compared with late treadmill exercise and no exercise. Early exercise may prevent neurodegeneration and functional loss by inhibiting neuroinflammation.

Low-Frequency Electrical Stimulation of Denervated Skeletal Muscle Retards Muscle and Trabecular Bone Loss in Aged Rats.

Electrical stimulation (ES)-induced muscle contraction has multiple effects; however, mechano-responsiveness of bone tissue declines with age. Here, we investigated whether daily low-frequency ES-induced muscle contraction treatment reduces muscle and bone loss and ameliorates bone fragility in early-stage disuse musculoskeletal atrophy in aged rats. Twenty-seven-month-old male rats were assigned to age-matched groups comprising the control (CON), sciatic nerve denervation (DN), or DN with direct low-frequency ES (DN+ES) groups. The structural and mechanical properties of the trabecular and cortical bone of the tibiae, and the morphological and functional properties of the tibialis anterior (TA) muscles were assessed one week after DN. ES-induced muscle contraction force mitigated denervation-induced muscle and trabecular bone loss and deterioration of the mechanical properties of the tibia mid-diaphysis, such as the stiffness, but not the maximal load, in aged rats. The TA muscle in the DN+ES group showed significant improvement in the myofiber cross-sectional area and muscle force relative to the DN group. These results suggest that low-frequency ES-induced muscle contraction treatment retards trabecular bone and muscle loss in aged rats in early-stage disuse musculoskeletal atrophy, and has beneficial effects on the functional properties of denervated skeletal muscle.

Behavioral Effect of Short- and Long-Term Exercise on Motor Functional Recovery after Intracerebral Hemorrhage in Rats.

BACKGROUND: In this study, we investigated the effects of short- and long-term exercise on motor functional recovery following intracerebral hemorrhage (ICH) in rats. METHODS: Male Wistar rats were randomly divided into 5 experimental groups: ICH without training (ICH group), ICH with long-term exercise for 14days from the second day after surgery (ICH + LT group), ICH with short-term exercise for 7days from the second day after surgery (ICH + EST group), ICH with short-term exercise for 7days from the ninth day after surgery (ICH + LST group), and sham operation without training (SHAM group). ICH was induced by collagenase injection into the left striatum. Forelimb sensorimotor function was evaluated using forelimb placing and horizontal ladder tests. RESULTS: In the behavioral test, the ICH + LT and ICH + EST groups improved significantly compared with the ICH and ICH + LT groups. The ICH + LT and ICH + EST groups recovered motor function in an almost analogous pattern. CONCLUSIONS: Our results indicated that, when exercise was started from an early phase after ICH, both short- and long-term exercises had similar benefits on motor functional recovery. However, continuous training using simple treadmill running may have limitations to motor functional recovery.

Effects of Streptomycin Administration on Increases in Skeletal Muscle Fiber Permeability and Size Following Eccentric Muscle Contractions.

The purpose of this study was to investigate the preventive effect of streptomycin (Str) administration on changes in membrane permeability and the histomorphological characteristics of damaged muscle fibers following eccentric contraction (ECC ). Eighteen 7-week-old male Fischer 344 rats were randomly assigned to three groups: control (Cont), ECC, and ECC with Str (ECC + Str). The tibialis anterior (TA) muscles in both ECC groups were stimulated electrically and exhibited ECC. Evans blue dye (EBD), a marker of muscle fiber damage associated with increased membrane permeability, was injected 24 hr before TA muscle sampling. The number of EBD-positive fibers, muscle fiber cross-sectional area (CSA), and roundness were determined via histomorphological analysis. The ECC intervention resulted in an increased fraction of EBD-positive fibers, a larger CSA, and decreased roundness. The fraction of EBD-positive fibers was 79% lower in the ECC + Str group than in the ECC group. However, there was no difference in the CSA and roundness of the EBD-positive fibers between the two ECC groups. These results suggest that Str administration can reduce the number of myofibers that increase membrane permeability following ECC, but does not ameliorate the extent of fiber swelling in extant EBD-positive fibers. Anat Rec, 301:1096-1102, 2018. © 2018 Wiley Periodicals, Inc.

Electrical Stimulation of Denervated Rat Skeletal Muscle Retards Capillary and Muscle Loss in Early Stages of Disuse Atrophy.

The purpose of the present study is to investigate the effects of low-frequency electrical muscle stimulation (ES) on the decrease in muscle mass, fiber size, capillary supply, and matrix metalloproteinase (MMP) immunoreactivity in the early stages of denervation-induced limb disuse. Direct ES was performed on the tibialis anterior muscle following denervation in seven-week-old male rats. The rats were divided into the following groups: control (CON), denervation (DN), and denervation with direct ES (DN + ES). Direct ES was performed at an intensity of 16 mA and a frequency of 10 Hz for 30 min per day, six days a week, for one week. We performed immunohistochemical staining to determine the expression of dystrophin, CD34, and MMP-2 in transverse sections of TA muscles. The weight, myofiber cross-sectional area (FCSA), and capillary-to-fiber (C/F) ratio of the tibialis anterior (TA) muscle were significantly reduced in the DN group compared to the control and DN + ES groups. The MMP-2 positive area was significantly greater in DN and DN + ES groups compared to the control group. These findings suggest beneficial effects of direct ES in reducing muscle atrophy and capillary regression without increasing MMP-2 immunoreactivity in the early stages of DN-induced muscle disuse in rat hind limbs.

Electrical Stimulation of Denervated Rat Skeletal Muscle Ameliorates Bone Fragility and Muscle Loss in Early-Stage Disuse Musculoskeletal Atrophy.

We tested whether daily muscle electrical stimulation (ES) can ameliorate the decrease in cortical bone strength as well as muscle and bone geometric and material properties in the early stages of disuse musculoskeletal atrophy. 7-week-old male F344 rats were randomly divided into three groups: age-matched control group (Cont); a sciatic denervation group (DN); and a DN + direct electrical stimulation group (DN + ES). Denervated tibialis anterior (TA) muscle in the DN + ES group received ES with 16 mA at 10 Hz for 30 min/day, 6 days/week. Micro CT, the three-point bending test, and immunohistochemistry were used to characterize cortical bone mechanical, structural, and material properties of tibiae. TA muscle in the DN + ES group showed significant improvement in muscle mass and myofiber cross-sectional area relative to the DN group. Maximal load and stiffness of tibiae, bone mineral density estimated by micro CT, and immunoreactivity of DMP1 in the cortical bone tissue were also significantly greater in the DN + ES group than in the DN group. These results suggest that daily ES-induced muscle contraction treatment reduced the decrease in muscle mass and cortical bone strength in early-stage disuse musculoskeletal atrophy and is associated with a beneficial effect on material properties such as mineralization of cortical bone tissue.