Karin Piehl-Aulin

Effects of combined lower body endurance and upper body resistance training on the satellite cell pool in elderly subjects

To distinguish the respective potential of endurance and resistance training to increase the satellite cell pool, we investigated the effects of 14 weeks of concurrent lower body endurance and upper body resistance training (3 sessions/week) on vastus lateralis (VLat) and deltoid (Del) muscles of 10 active elderly men. NCAM+ satellite cells and myonuclear number were assessed in VLat and Del. After 14 weeks of training the NCAM+ satellite cell pool increased similarly (+38%) in both muscles, mainly in type II muscle fibers (P < 0.05). There was no significant change in myonuclear number or myonuclear domain in either muscle. Combining resistance training in the upper limbs with endurance training in the lower limbs is an efficient strategy to enhance the satellite cell pool in upper and lower body muscles in elderly subjects. Our results provide a practical reference for the determination of optimal exercise protocols to improve muscle function and regeneration in the elderly. Muscle Nerve, 2008

Correlates of objectively assessed physical activity and sedentary time in children: a cross-sectional study (The European Youth Heart Study)

BackgroundIdentifying leisure time activities performed before and after school that influence time in physical activity (PA) and/or time spent sedentary can provide useful information when designing interventions aimed to promote an active lifestyle in young people. The purpose of this study was to examine associations between mode of transportation to school, outdoor play after school, participation in exercise in clubs, and TV viewing with objectively assessed PA and sedentary behaviour in children.MethodsA total of 1327 nine- and 15-year-old children from three European countries (Norway, Estonia, Portugal) participated as part of the European Youth Heart Study. PA was measured during two weekdays and two weekend days using the MTI accelerometer, and average percent of time in moderate-to-vigorous PA (MVPA) and time spent sedentary were derived. Potential correlates were assessed by self-report. Independent associations between self-reported correlates with percent time in MVPA and percent time sedentary were analysed by general linear models, adjusted by age, gender, country, measurement period, monitored days and parental socio-economic status.ResultsIn 9-year-olds, playing outdoors after school was associated with higher percent time in MVPA (P < 0.01), while participation in sport clubs was associated with higher percent time in MVPA (P < 0.01) in 15-year-olds. No associations with percent time sedentary were observed in either age group.ConclusionFrequency of outdoor play after school is a significant correlate for daily time in MVPA in 9-year-olds, while this correlate is attenuated in favour of participation in sport and exercise in clubs in 15-year-olds. Targeting walking to school or reduced TV viewing time in order to increase time in daily MVPA in children is unlikely to be sufficient. Correlates related to time spent sedentary need further examination.

Increased Serum Inflammatory Markers in the Absence of Clinical and Skeletal Muscle Inflammation in Patients with Chronic Obstructive Pulmonary Disease

Background: Muscle wasting and cachexia are common occurrences in patients with chronic obstructive pulmonary disease (COPD). Objectives: The current study aimed to investigate markers of inflammation in the circulation and skeletal muscle that might be associated with development of muscle wasting. Methods: Three groups of patients with mild, moderate and severe COPD and matched healthy controls were recruited. Serum levels of C-reactive protein (CRP), high-sensitivity CRP (hs-CRP), IL-6, IL-8, TNF-α, cortisol, insulin-like growth factor 1 (IGF-1), leptin and ghrelin were analysed. Skeletal muscle inflammation was investigated microscopically using a panel of antibodies and standard staining for inflammatory cell infiltration. Results: All COPD patients were clinically stable, with no sign of inflammation and normal CRP values. Compared to controls, significantly increased hs-CRP levels were observed in all COPD patient groups. Significant rises in IL-6 levels were first observed in moderate COPD, while IL-8 levels were significantly elevated at the late severe stage. Circulating levels of TNF-α, cortisol, IGF-1, leptin and ghrelin were similar to control levels. No microscopic signs of skeletal muscle inflammation were observed. Conclusion: Our results identify hs-CRP as an early marker of inflammation that is significantly increased in the circulation even in mild COPD. Serum interleukin levels appear to be increased with disease progress. These changes were manifested in the absence of any clinical signs of disease exacerbation, evidence of skeletal muscle inflammation or hormonal changes.

Overexpression of von Hippel-Lindau protein in skeletal muscles of patients with chronic obstructive pulmonary disease

Background: A significant number of patients with chronic obstructive pulmonary disease (COPD) exhibit skeletal muscle wasting and decreased capillary area formation, which correlate with increased mortality. Aim: To determine the molecular mechanisms mediating decreased capillary formation in COPD. Methods: 24 patients with COPD and 12 matching controls were recruited. Patients with COPD were classified into mild, moderate and severe groups according to GOLD (global initiative for chronic obstructive lung disease) criteria. Biopsy specimens were obtained from the tibialis anterior muscle. Fibre typing and capillary formation, together with messenger RNA (mRNA) expression of hypoxia-inducible factors (HIF1α and HIF3α), vascular endothelial growth factors (VEGF-A, VEGF-B and VEGF-C isoforms) and von Hippel-Lindau (VHL) protein, were determined. VHL expression and localisation were further studied by immunohistochemistry. Results: Skeletal muscle capillary formation decreased significantly with increasing disease severity. Compared with controls, a tendency to mRNA overexpression of HIF1α, HIF3α and VEGF isoforms was observed in mild and moderate COPD, which decreased at the severe stage. In contrast, skeletal muscle biopsy samples from patients with COPD exhibited significant overexpression of VHL at both the mRNA and protein level by immunohistochemistry. VHL protein was further determined to be localised to satellite cells. Conclusions: Overexpression of VHL was identified in the skeletal muscle of patients with COPD. Increased VHL activity may have a negative effect on transduction of the hypoxic signal and may contribute to decreased capillarisation in skeletal muscles of patients with COPD.

Physical performance and muscular characteristics in different stages of COPD

This study has examined exercise capacity and muscle morphology in patients with different severities of chronic obstructive pulmonary disease (COPD). Twenty‐three patients and 12 healthy matched controls were recruited. Based on the severity of airflow obstruction, patients were divided into two subgroups. Exercise capacity was determined using a 6‐min walk test. Muscle fiber composition, fiber area and number of satellite cells/muscle fiber were determined in muscle biopsies using immunohistochemistry. A progressive decline in exercise capacity was noted with ascending disease severity. Furthermore, a correlation between reduction in exercise capacity and changes in muscle fiber composition was observed in COPD. The group with severe and very severe COPD had a lower proportion of type I and a higher proportion of type IIa fibers compared with the other groups. In severe and very severe COPD, a reduction in fiber area of type IIa fibers was also seen. The number of satellite cells/muscle fiber did not differ between the groups. In conclusion, a decline in exercise capacity occurs already in mild and moderate COPD, indicating that the 6‐min walk test is a reliable indicator of disease severity. Furthermore, changes in skeletal muscle morphology are associated with disease severity while muscle regenerative capacity is not altered.

Alterations in the muscle-to-capillary interface in patients with different degrees of chronic obstructive pulmonary disease

AbstractBackgroundIt is hypothesized that decreased capillarization of limb skeletal muscle is implicated in the decreased exercise tolerance in COPD patients. We have recently demonstrated decreased number of capillaries per muscle fibre (CAF) but no changes in CAF in relation to fibre area (CAFA), which is based on the diffusion distance between the capillary and muscle fibre. The aim of the current study is to investigate the muscle-to-capillary interface which is an important factor involved in oxygen supply to the muscle that has previously been suggested to be a more sensitive marker for changes in the capillary bed compared to CAF and CAFA.Methods23 COPD patients and 12 age-matched healthy subjects participated in the study. Muscle-to-capillary interface was assessed in muscle biopsies from the tibialis anterior muscle using the following parameters: 1) The capillary-to-fibre ratio (C:Fi) which is defined as the sum of the fractional contributions of all capillary contacts around the fibre2)The ratio between C:Fi and the fibre perimeter (CFPE-index)3)The ratio between length of capillary and fibre perimeter (LC/PF) which is also referred to as the index of tortuosity. Exercise capacity was determined using the 6-min walking test.ResultsA positive correlation was found between CFPE-index and ascending disease severity with CFPE-index for type I fibres being significantly lower in patients with moderate and severe COPD. Furthermore, a positive correlation was observed between exercise capacity and CFPE-index for both type I and type IIa fibres.ConclusionIt can be concluded that the muscle-to-capillary interface is disturbed in the tibialis anterior muscle in patients with COPD and that interface is strongly correlated to increased disease severity and to decreased exercise capacity in this patient group.

The expression of heat shock protein in human skeletal muscle: effects of muscle fibre phenotype and training background

Exercise‐induced adaptations of skeletal muscle are related to training mode and can be muscle fibre type specific. This study aimed to investigate heat shock protein expression in type I and type II muscle fibres in resting skeletal muscle of subjects with different training backgrounds.

Physical activity patterns in patients in different stages of chronic obstructive pulmonary disease

It has previously been suggested that exercise capacity is decreased in COPD and that it is associated with degree of disease. The reduced exercise capacity may plausibly be due to low levels of physical activity in this patient group. The aim of the present study was to assess exercise capacity and physical activity in different stages of COPD and to examine the associations between exercise capacity, pulmonary function and degree of physical activity. A total of 44 COPD patients and 17 healthy subjects participated in the study. Exercise capacity was assessed using the 6-minute walking test and physical activity was assessed using an accelerometer worn all waking hours during 7 days. Mean exercise capacity was significantly lower in COPD patients compared with healthy subjects. Mean physical activity level and time spent at least moderately active were significantly lower in patients with moderate and severe COPD compared with healthy subjects while no differences in time spent sedentary were observed between the study groups. Pulmonary function, mean physical activity level and time spent at least moderately physically active were significantly associated with exercise capacity in the patients. We conclude that patients with moderate and severe COPD are less physically active compared with healthy subjects. Furthermore, mean physical activity level and physical activity of at least moderate intensity are positively associated with exercise capacity in COPD, while time spent sedentary is not, which stresses an important role of physical activity on exercise capacity in these patients.

INCREASED LEFT VENTRICULAR MUSCLE MASS AFTER LONG-TERM ALTITUDE TRAINING IN ATHLETES 810

The effects of long-term altitude training on altitude and sea-level physiological characteristics in elite endurance athletes were investigated. Seven Swedish elite cross-country skiers (five men, two women; mean age 27 years) spent 1 month training at 1900 m above sea level in Italy. Rollerski treadmill tests were performed before and 5 and 11 days after the altitude sojourn; three tests were also performed at altitude. Before and 1, 11 and 35 days after the altitude camp, echocardiographic and blood volume measurements were performed. The heart rates at both maximal (P < 0.05) and submaximal (P < 0.01) work loads were decreased by 5-9 beats min-1 at altitude. The haemoglobin concentration and haematocrit increased quickly at altitude with a corresponding decrease on return to sea level. The blood volume (7%) and total haemoglobin (3%) tended to be higher day 11 post-altitude (NS). There were no significant changes in diastolic internal diameter or wall thickness of the left ventricle, but the calculated cardiac left ventricular muscle mass was increased post-altitude (9-10%, P < 0.01). The maximal oxygen uptake increased in six of the seven skiers after the altitude training (day 11, mean 3%, NS). In conclusion, training at moderate altitude may cause a reduction in heart rates during exercise. Moreover, after long-term training at altitude, there may be an increase in the cardiac left ventricular muscle mass.