Harri Suominen

Effects of hormone replacement therapy and high-impact physical exercise on skeletal muscle in post-menopausal women: a randomized placebo-controlled study.

An age-related decline in muscle performance is a known risk factor for falling, fracture and disability. In women, a clear deterioration is observed from early menopause. The effect of hormone replacement therapy (HRT) in preserving muscle performance is, however, unclear. This trial examined the effects of a 12-month HRT and high-impact physical exercise regimen on skeletal muscle in women in early menopause. A total of 80 women aged 50-57 years were assigned randomly to one of four groups: exercise (Ex), HRT, exercise+HRT (ExHRT) and control (Co). The exercise groups participated in a high-impact training programme. The administration of HRT (oestradiol/noretisterone acetate) or placebo was carried out double-blind. Knee extension torque and vertical jumping height were evaluated. Lean tissue cross-sectional area (LCSA) and the relative proportion of fat within the muscle compartment were measured for the quadriceps and lower leg muscles. The ExHRT group showed significant increases in knee extension torque (8.3%) and vertical jumping height (17.2%) when compared with the Co group (-7.2%). Vertical jumping height also increased after HRT alone (6.8%). The LCSA of the quadriceps was increased significantly in the HRT (6.3%) and ExHRT (7.1%) groups when compared with the Ex (2.2%) and Co (0.7%) groups. Lower leg LCSA was also increased in the ExHRT group (9.1%) when compared with the Ex (3.0%) and Co (4.1%) groups. In addition, the increase in the relative proportion of fat in the quadriceps in the Co group (16.6%) was significant compared with those in the HRT (4.9%) and ExHRT (-0.6%) groups. Thus, in post-menopausal women, muscle performance, muscle mass and muscle composition are improved by HRT. The beneficial effects of HRT combined with high-impact physical training may exceed those of HRT alone.

Assessing Body Composition With DXA and Bioimpedance: Effects of Obesity, Physical Activity, and Age

Objective: This study evaluated to what extent dual‐energy X‐ray absorptiometry (DXA) and two types of bioimpedance analysis (BIA) yield similar results for body fat mass (FM) in men and women with different levels of obesity and physical activity (PA).

Bone mineral density and long term exercise : an overview of cross-sectional athlete studies

SummaryEvidence in human studies of the association of long term habitual exercise with bone mineral content (BMC) and density (BMD) largely comes from studies in athletes. In young adults, the highest BMC and BMD values have been found in strength and power-trained athletes, while endurance activities such as long distance running and swimming seem less effective with regard to peak bone density. Intensive endurance training may even be associated with amenorrhoea and decreased trabecular bone density in young females. However, after menopause female athletes show greater bone mass indicating that they do not share the accelerated decline in BMC observed in a nonathletic population. Middle-aged and elderly male athletes from various sports have significantly higher BMC and BMD than controls, especially in trabecular bone sites, but higher cortical BMC has also been found in the dominant/nondominant arm comparisons with unilateral exercises such as tennis. The differences found between female athletes and controls have generally been less pronounced than those among men, but a number of studies suggest that in women long term physical training may counteract the low BMC and BMD associated with reduced bone mass. Although the interpretation of results of cross-sectional studies should be treated with caution, studies in athletes serve as an economical alternative approach to experimental trials with their long term follow-up and exercise compliance problems. The differences found in BMD between those who have devoted themselves to life-long training and those who have been much less active should not be underestimated.

Serum tartrate-resistant acid phosphatase 5b, but not 5a, correlates with other markers of bone turnover and bone mineral density.

Human serum contains two isoforms of tartrate-resistant acid phosphatase (TRACP) known as TRACP 5a and TRACP 5b with pH optima of 5.0 and 5.8, respectively. Preliminary data suggest that serum TRACP 5b is derived from osteoclasts and serum TRACP 5a from some other cells. It has been reported that heparin inhibits TRACP 5a but has no effect on the activity of TRACP 5b. Here we show that heparin has no effect on serum TRACP activity, as determined using our previously published immunoassay, suggesting that the immunoassay does not detect TRACP 5a. The change of serum TRACP 5b activity after 6 months HRT, determined by this immunoassay, correlated significantly with the changes of all markers of bone turnover determined, including serum N- and C-terminal propeptides of type I collagen and urinary-free deoxypyridinoline. Serum TRACP 5b activity was significantly elevated in patients with osteoporosis and had a significant negative correlation with bone mineral density (BMD). Serum TRACP 5a activity, determined by an immunoassay, showed no correlation with serum TRACP 5b activity, with BMD, or with any of the markers of bone turnover. These results show that serum TRACP 5b, but not 5a, reflects the bone resorption rate, and that our TRACP 5b immunoassay may be a specific method for the determination of the bone resorption rate from serum samples.

Mechanical properties of fast and slow skeletal muscle with special reference to collagen and endurance training.

The mechanical properties of the slow soleus and the fast rectus femoris muscle under passive stretching were studied in endurance trained, untrained and lathyritic rats, aged 3 months. The soleus muscle with more abundant and cross-linked collagen had higher ultimate tensile strength and tangent modulus compared to the fast rectus femoris muscle which, on the other hand, had higher maximum strain. The inhibition of collagen cross-linking by lathyrism resulted in decreased tensile strength and stiffness, especially in the soleus muscle, whereas endurance training showed the opposite effects. It is supposed that the properties of collagen partly explain the capacity of slow muscles to maintain posture and to perform prolonged dynamic work. The effects of training on the tensile properties further indicate the close relationship between intramuscular collagen and the endurance capacity of muscles.

Effects of diet-induced obesity and voluntary wheel running on the microstructure of the murine distal femur

BackgroundObesity and osteoporosis, two possibly related conditions, are rapidly expanding health concerns in modern society. Both of them are associated with sedentary life style and nutrition. To investigate the effects of diet-induced obesity and voluntary physical activity we used high resolution micro-computed tomography (μCT) together with peripheral quantitative computed tomography (pQCT) to examine the microstructure of the distal femoral metaphysis in mice.MethodsForty 7-week-old male C57BL/6J mice were assigned to 4 groups: control (C), control + running (CR), high-fat diet (HF), and high-fat diet + running (HFR). After a 21-week intervention, all the mice were sacrificed and the left femur dissected for pQCT and μCT measurements.ResultsThe mice fed the high-fat diet showed a significant weight gain (over 70% for HF and 60% for HFR), with increased epididymal fat pad mass and impaired insulin sensitivity. These obese mice had significantly higher trabecular connectivity density, volume, number, thickness, area and mass, and smaller trabecular separation. At the whole bone level, they had larger bone circumference and cross-sectional area and higher density-weighted maximal, minimal, and polar moments of inertia. Voluntary wheel running decreased all the cortical bone parameters, but increased the trabecular mineral density, and decreased the pattern factor and structure model index towards a more plate-like structure.ConclusionsThe results suggest that in mice the femur adapts to obesity by improving bone strength both at the whole bone and micro-structural level. Adaptation to running exercise manifests itself in increased trabecular density and improved 3D structure, but in a limited overall bone growth

Muscle training for bone strength

The main function of bone is to provide the mechanical integrity for locomotion and protection; accordingly, bone mass and architecture are adjusted to control the strains produced by mechanical load and muscular activity. Age-related patterns involve peak bone mass during growth, a plateau in adulthood, and bone loss during aging. The decline in bone mass and structural integrity results in increased risk of fractures, particularly in post-menopausal women. Athletes competing in strength and power events, such as weight-lifting and jumping, have superior bone mass and structure compared with their untrained counterparts in all age groups. Exercise seems to be most effective during rapid growth, the average gain in bone mineral content (BMC) and density (BMD) in controlled trials being of the order of 2–5% per year. The net gain of BMD after exercise interventions among older people is modest, at a level of 1–3% per year, but it is not clear whether positive effects can be maintained over a longer time. Although aerobic exercise is important in maintaining overall health, the resistance type of muscle training may be more applicable to the basic rules of bone adaptation and site-specific effects of exercise, have more favorable effects in maintaining or improving bone mass and architecture, and be safe and feasible for older people. It has been suggested that there is an opportunity for resistance training, for improved effects on BMD in post-menopausal women in bones which have less daily loading. In addition to BMC and BMD, bone geometry and mass distribution may also change as a result of training and other treatment, such as hormonal replacement therapy, thereby further improving bone strength and reducing fracture risk. Appropriate training regimens may reduce the risk of falls and the severity of fall-related injuries, and also constitute potential therapy to improve functional ability and the quality of life in osteoporotic patients. However, further research is needed on dose-response relationships between exercise and bone strength, the feasibility of high-load, high-speed and impact-type of physical training, and the risks and benefits of intensive exercise in elderly individuals.

Change in bone mass distribution induced by hormone replacement therapy and high-impact physical exercise in post-menopausal women

The purpose of this intervention trial was to determine whether changes in bone mass distribution could be observed in postmenopausal women following hormone replacement therapy (HRT) and/or high-impact physical exercise. Eighty healthy women, aged 50-57 years, at <5 years after the onset of menopause and with no previous use of HRT, were randomly assigned to one of four groups: HRT; exercise (Ex); HRT + Ex (ExHRT); and control (Co). HRT administration was conducted in a double-blind manner for 1 year using estradiol plus noretisterone acetate (Kliogest). The exercise groups participated in a 1 year progressive training program consisting of jumping and bounding activities. Subjects participated in two supervised sessions per week and were asked to perform a series of exercises at home 4 days/week. Bone measurements using a quantitative computed tomography scanner (Somatom DR, Siemens) were obtained from the proximal femur, midfemur, proximal tibia, and tibial shaft. Data were analyzed with a software program (BONALYSE 1.3) calculating density (g/cm(3)), cross-sectional area (CSA; mm(2)), and moments of inertia (I(max), I(min), I(polar)). In addition, the bone mass spectrum was determined as a function of the angular distribution around the bone mass center (polar distribution) and the distance from the bone mass center through the diaphyseal wall (radial distribution). After the 1 year period, there was an overall interaction of group x time in bone mineral density (BMD) at the proximal femur (p = 0.05) and tibial shaft (p = 0.035). Women in the ExHRT and HRT groups had increased proximal femur and tibial shaft BMD when compared with the change observed in the Co group (p = 0.024-0.011). The change was more pronounced in the cortical tibia, wherein the ExHRT group also differed from the Ex group (p = 0.038). No significant changes were found in bone CSA at any of the measured sites. The radial distribution indicated an increase of BMD in the endocortical part of the measured sites in the HRT and ExHRT groups and in the proximal tibia in the Ex group. The polar distribution showed that bone mass was redistributed in the anteroposterior direction. The changes in I(max), I(min), and I(polar) in the HRT and ExHRT groups differed from those in the Co group at the proximal femur, midfemur, and proximal tibia (p = 0.047-0.001). The Ex group also differed from the Co group in I(max) and I(polar) at the proximal tibia (p = 0.018 and 0.039, respectively). These results support the idea that HRT acts primarily at the bone-marrow interface. The exercise intervention chosen for this study contributed to the maintenance of bone mass. Our results suggest that both HRT and exercise have local effects on bone mass. The change in bone mass distribution induced by HRT and exercise may play an important role in the alteration of bone strength.

The effect of hormone replacement therapy and/or exercise on skeletal muscle attenuation in postmenopausal women: a yearlong intervention

Hormone replacement therapy (HRT) has been reported to exert a positive effect on preserving muscle strength following the menopause, however, the mechanism of action remains unclear. We examined whether the mechanism involved preservation of muscle composition as determined by skeletal muscle attenuation. Eighty women aged 50–57 years were randomly assigned to either: HRT, exercise (Ex), HRT + exercise (ExHRT), and control (Co) for 1 year. The study was double‐blinded with subjects receiving oestradiol and norethisterone acetate (Kliogest) or placebo. Exercise included progressive high‐impact training for the lower limbs. Skeletal muscle attenuation in Hounsfield units (HU) was determined by computed tomography of the mid‐thigh. Areas examined were the quadriceps compartment (includes intermuscular adipose tissue), quadriceps muscles, the posterior compartment and posterior muscles. Muscle performance was determined by knee extensor strength, vertical jump height, and running speed over 20 m. Fifty‐one women completed the intervention. Vertical jump height and running speed improved in the HRT and ExHRT groups compared with Co (interaction, P<0·01). For both the quadriceps compartment and quadriceps muscles, HU significantly increased (interaction, P≤0·005) for HRT, Ex, and ExHRT compared with Co. For the posterior compartment, HU for the HRT and ExHRT were significantly increased compared with Co, while for posterior muscles, ExHRT was significantly greater than Co. Although the effects were modest, the results indicate that HRT, either alone or combined with exercise, may play a role in preserving/improving skeletal muscle attenuation in early postmenopausal women and thereby exert a positive effect on muscle performance.

Calcaneal Bone Mineral Density Predicts Fracture Occurrence: A Five‐Year Follow‐up Study in Elderly People

A 5‐year follow‐up study investigated calcaneal bone mineral density (BMD) and changes in BMD in relation to fracture occurrence. The subjects comprised two cohorts born in 1914 and 1910 living in the city of Jyväskylä in central Finland. One hundred and three men (82%) and 188 women (73%), aged 75, and 57 men (74%) and 136 women (65%), aged 80, of the eligible population participated in the baseline bone measurements. The follow‐up bone measurements were obtained for 59 men (68%) and 119 women (66%), aged 80 years, and for 21 men (53%) and 61 women (48%), aged 85 years. During the follow‐up period, 8 men and 36 women from the younger and 11 men and 24 women from the older cohort sustained at least one fracture. When the baseline levels of BMD were related to fracture occurrence, the results clearly showed that with increased BMD values the probability of fracture decreased. Where men and women had similar BMD values, they also had a similar fracture probability. Except for one woman in the older cohort, none of those who had initial BMD values more than 1 standard deviation above the mean for their age developed a fracture during the follow‐up period. The mean annual decrease in BMD was greater in the women (2.5–2.7%) than in the men (0.8–1.0%). The BMD change tended to associate with fracture occurrence only in the 75‐year‐old women (p = 0.075). The results suggest that calcaneus BMD can be used as a predictor of fracture occurrence in 75− to 80‐year‐old men and women. However, associating fractures with the change in BMD was difficult due to the limited number of survivors and initial differences in BMD values.