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.

The effects of dynamic and isometric muscle contractions on the lymph flow dynamics in human skeletal muscle were studied with a scintographic method. Radioactively labelled human serum albumin (99mTc‐HSA) was injected bilaterally into the vastus lateralis muscles of eight men (n= 16), four of whom had had an endurance training background. The subjects performed 100 submaximal contractions in 10 min as (i) dynamic knee extensions (CONS), (ii) isometric contractions with the knees at full extension (IMExt), or (iii) isometric contractions with knees fixed at 90 deg angle flexion (IMFlex). The exercises were separated by 65 min periods in supine rest. The level of radioactivity at the injection site was monitored by a gamma‐camera, and the clearance rate of radioactivity (CR) was calculated as the fractional decrease during the periods of interest (CR unit =% min−). The clearance rate was low during the rest periods (0.04 ± 0.05% min−1), though higher in the trained than in the sedentary subjects (0.06 ± 0.05 vs. 0.03 ± 0.03% min−1; P= 0.008). Exercise increased the clearance rate three‐ to sixfold, to 0.16 ± 0.16% min−1 during CONS, 0.20 ± 0.15% min− during IMExt and 0.09 ± 0.11 % min−1 during IMFlex. There were no differences between the subject subgroups. The higher clearance rate during IMExt than during IMFlex (P= 0.02) demonstrates the importance of muscle deformations on lymph propulsion and experimentally confirms the current concepts of lymph formation and propulsion in voluntarily active skeletal muscle. It is suggested that lymph propulsion by working muscle is most efficient when the muscle is able to shorten close to its minimum length.

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

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.

PurposeThe purpose of this paper is to study how, in recent decades, manufacturing sites have reacted to changes in their business environment by developing their management practices. This also makes it possible to predict the behavior and lifecycles of the new practices adopted by companies.Design/methodology/approachThe study is longitudinal, conducted in 1993, 2004 and 2010. It used a standard questionnaire, based on the “Made in Europe” benchmarking study. The results were analysed by Friedman's rank order method. The use of a three (or more) data‐point longitudinal study is the clearest way to reveal changes in, and the behaviour of, the practices.FindingsThe data suggest that there is a lifecycle for the practices used in companies and that many of the practices adopted in the late 1990s are already out of date. However, personnel‐related practices seem to last longer than process‐related practices. Furthermore, these practices seem to follow the curve of the Bass diffusion model.Research limitations/implicationsThe results are restricted to the sample which is quite small in size, but gives a good insight into the changes occurring within it. This research excludes new practices adopted in recent years, and uses only the questions designed for the first year in which the study was conducted. However, its purpose is to show the evolution of some practices in the form of a unique, longitudinal study. The study also indicates the lifecycles of the practices included in the sample.Originality/valueThis study is the only longitudinal study in its field to use data from three different time periods. It can thus look into and analyze change from a unique perspective.