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.

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.

In general, physical exercise appears to have favorable effects on the skeleton. However, a few recent reports have described negative effects, including reduced bone density (BMD) and high bone turnover in runners. The aim of our study was to compare endurance runners to controls with respect to BMD at different sites and ultrasound transmission through the peripheral skeleton, and to use PTH, total serum calcium, and biochemical markers of bone metabolism as a complement in evaluating the effects of endurance running on bone. Thirty runners (mean age 32 years, range 19-54 years) participated in the study. Their main form of training consisted of endurance running at moderate intensity for about 7 hours (range 2-12 hours) per week, and they had been active in their sport for about 12 years (range 1-21 years). For a comparison, 30 age- and sex-matched population based controls were investigated. BMD values, measured by dual energy X-ray absorptiometry (DXA), were higher in runners than in controls for the total body (3.6%; P = 0.03), legs (9.6%; P = 0. 001), femoral neck (10.0%; P = 0.01), trochanter (9.9%; P = 0.01), and Wards triangle (11.8%; P = 0.02), but not in the lumbar spine or in the forearm measured by single energy X-ray absorptiometry (SXA). The quantitative ultrasound measurement of the calcaneus also revealed higher values in runners than in controls for both broadband ultrasound attenuation (9.2%; P = 0.002) and speed of sound (3.1%; P = 0.0001). At all sites, BMD was related to ultrasound measurements in controls, but no such relationship was evident in runners. Concentrations of parathyroid hormone (PTH) were lower (23.2%; P = 0.02) in runners than in controls, whereas total serum calcium concentrations were slightly higher (3.0%; P = 0.003). The levels of PICP (bone formation) and ICTP (bone resorption) in serum were lower (18.0%; P = 0.03 and 22.2%; P = 0.004, respectively) in runners than in controls, but no differences were seen for osteocalcin or bone specific alkaline phosphatase (b-ALP). In conclusion, BMD at the focus of strain for running, that is, the legs, is higher in endurance runners when compared to matched controls. Low bone turnover in runners, indicated by lower levels of PTH and biochemical markers of bone metabolism, point to an influence of endurance running at the cellular level.

Understanding the reaction of bone to physical exercise is important for the development of strategies to increase and maintain bone mass. In this study the aim was to investigate the relationship among exercise intensity, physical capacity, and the biochemical responses, estimated by measuring biochemical markers of bone metabolism in serum. As a complement to the circulating concentrations we also accounted for the plasma volume shifts during and after exercise. The study included 10 men and 10 women, mean age 29 years, with a wide range of physical capacity, who performed a standardized running exercise test on a motor-driven treadmill with loads corresponding to 47 and 76% of VO2 max (maximal oxygen uptake) followed by a maximal effort until exhaustion. Total work time was about 35 minutes. Venous blood samples were drawn at rest, after each load, and after 30 minutes and 24 hours of recovery. The reductions in plasma volume during exercise were 4.3% (P < 0.05) and 15.1% (P < 0.001) whereas after 24 hours in recovery there was an expansion of 7.5% (P < 0.001). There were marked, intensity-related, increases of PICP and tALP concentrations (P < 0.001) during exercise. Since these were of the order of plasma volume reduction they did not correspond to a change in the calculated circulating amount (content). However, as the concentrations returned to basal during recovery, the total circulating amounts were increased at this point (P < 0.05). Osteocalcin was also increased during recovery (P < 0.01), although concentrations were unchanged during the entire study. The amount (P < 0.001) and concentration (P < 0. 05) of ICTP were also increased during follow-up. Serum PTH concentrations rose (P < 0.05) in proportion to the intensity of exercise and remained elevated during recovery. The subjects' VO2 max demonstrated positive relationships to the biochemical responses to exercise in bone and BMD of the legs, and a negative relationship to basal PTH levels. Bone turnover and PTH secretion was stimulated by exercise, and low basal levels of PTH and high BMD were induced by a high level of physical fitness. These observations correlate well with the favorable effects of exercise and training on bone mass.

The purpose of this study was to evaluate the responses of hormones, growth factors, and biomarkers involved in bone and muscle metabolism during exercise and in recovery. One leg knee-extension exercise and concomitant sampling from the artery and vein were performed. In 12 healthy individuals (6 men and 6 women; age 21-36 years) blood was drawn from the femoral artery and vein at rest, after 10 minutes warm-up, after 15 minutes work at 61% of peak one leg VO2, and after 5 minutes work at peak one leg VO2, as well as 5, 30, and 60 minutes in recovery. Blood flow in the femoral vein was measured using the thermodilution technique. Arteriovenous differences were measured over working thigh for growth hormone (GH), insulin-like growth factor I (IGF-I), insulin-like growth factor binding protein 3 (IGF BP3), parathyroid hormone (PTH) and bone biomarkers, i.e., the carboxyterminal propeptide of type I procollagen (PICP), the carboxyterminal cross-linked telopeptide of type I collagen (ICTP), osteocalcin, and bone-specific alkaline phosphatase (b-ALP). There was an uptake of GH (3.1 +/- 1.2 mU x min(-1), P < 0.001; mean +/- SE) over thigh during exercise and a release of IGF-I at the end of exercise (60 +/- 36 microg x min(-1); P < 0.01). PICP was also released after the maximal exercise (23 +/- 12 microg x min(-1); P < 0.01) as well as ICTP (0.5 +/- 0.3 microg x min(-1); P < 0.05) and b-ALP (0.2 +/- 0.1 microkat x min(-1); P < 0.05). Osteocalcin, IGF BP3, and PTH revealed no clearcut pattern. In the present study, exercise induces endocrine changes which point to anabolic effects on muscle and bone tissue.