The effect of tibolone on fat mass, fat-free mass, and total body water in postmenopausal women.

Changes in body composition occur around the menopausal transition. The major characteristics are a decline in fat-free mass and an increase in body fat as a percentage of body weight. These alterations might be affected by age only or by menopause-related changes in hormone concentration. In this study the effects of tibolone, a tissue-specific compound with favorable effects on bone, vagina, and climacteric symptoms, were determined on body composition using bioelectrical impedance analysis. The focus was especially on fat mass, fat-free mass, and total body water in a group of 85 healthy women (mean +/- SD age, 54.2 +/- 4.7 yr), between 1-15 yr postmenopausal. Participants were randomly assigned to either tibolone (2.5 mg; n = 42) or identically appearing placebo tablets (n = 43) daily for 12 months. All analyses were based on the intent to treat group and last visit. Compared with placebo, tibolone significantly increased fat-free mass by 0.85 kg (P = 0.003) and total body water by 0.78 liter (P = 0.001). No significant difference was observed on the fat mass parameter (P = 0.16). From these results it can be concluded that tibolone may counteract the postmenopausal changes in body composition.

Evaluation of the applicability of HRT as a preservative of muscle strength in women.

OBJECTIVES: To review the studies that have been undertaken on the effects of postmenopausal hormone replacement therapy (HRT); especially oestrogen (+progestin) regimens on the preservation of muscle strength. Current knowledge of the mechanisms and actions of steroid- and sex hormones on skeletal muscle tissue will be used in an attempt to clarify the mechanism of action of a possible effect. The objective is to arrive at an agreement on whether or not postmenopausal oestrogen administration has a positive influence on skeletal muscle tissue. METHODS: Peer-reviewed publications were assessed. RESULTS: An age-related decrement in muscle strength can be found in both men and women. However, in women, an extra decline can be observed around the time of menopause. A possible relationship between the additional diminution in muscle strength and altered hormone concentrations after the onset of menopause has been suggested. Since women nowadays spend one-third of their life postmenopausal, it is extremely important to keep the decline in muscle mass as small as possible. Besides the continuation of a physically active lifestyle, HRT was suggested to serve as a protective mechanism. Although, the usefulness of HRT as a preservative of muscle strength appeared controversial. CONCLUSIONS: Skeletal muscle strength is sensitive to training up to a high age, though continuation of physical activity does not appear to protect skeletal muscles completely from age-related decrements. Therefore, the development of another preventive method would be useful. Considering the present knowledge it has all the hallmarks that HRT can be a useful tool in the maintenance of muscle strength in postmenopausal women. None the less, further research is necessary to endorse this theory.

Relationships between physical performance measures, age, height and body weight in healthy adults.

OBJECTIVE: we measured muscle strength and functional mobility in healthy men and women over the adult age range to investigate the changes with age and sex, and to establish the effects of the anthropometric indices height and weight. DESIGN: cross-sectional study. SUBJECTS AND METHODS: we recruited 74 healthy women (mean age 49.0, range 20-90) and 81 healthy men (mean age 51.6, range 20-90). We measured maximum isometric knee extension strength, handgrip strength and explosive leg extensor power. We assessed functional mobility quantitatively with the timed 'get up and go' test and the modified Cooper test. RESULTS: older subjects had lower values for muscle strength and muscle power than young subjects. Times for the timed 'get up and go' test were longer and distances in the modified Cooper test shorter. At about the age of 55, women showed an acceleration in the decline of isometric knee extension strength and handgrip strength (between 20 and 55 years, knee strength decreased by 10.3% and handgrip strength decreased by 8.2%, between 55 and 80 years the decreases were 40.2% and 28% respectively). Men showed a more gradual declines over the adult age range, with decreases in knee and handgrip strength of 24% and 19.6% between 20 and 55 years, and 23% and 17.4% between 55 and 80 years. The age-related decline is partly associated with differences in height and body weight. Women had higher correlations between muscle strength and functional mobility tests than men. CONCLUSIONS: muscle strength and functional mobility decline with age in healthy people; in women we observed an accelerated decrement in muscle strength above the age of 55. Lower values in healthy old subjects are partly associated with differences in height and body weight.

Determination of oxygen consumption in muscle during exercise using near infrared spectroscopy.

The aim of this study was to determine oxygen consumption (VO2) during isometric exercise in human muscles using near infrared spectroscopy (NIRS). The technique was used to study the relationship between VO2 in the soleus muscle and the level of isometric exercise expressed as percentages of the maximum voluntary contraction (MVC). For the study 11 healthy male volunteers were recruited. Reproducibility was studied in 6 subjects. The subjects were seated in a chair with the knee joint at an angle of 90 degrees. The optodes of the NIRS instrument were attached to the lateral aspect of the soleus muscle. A horizontal bar above the knee was connected to a dynamometer. Subjects applied isometric force to the bar by producing a torque at the ankle joint. Firstly the MVC was determined. Secondly the VO2 at rest and at 5 levels of isometric exercise, ranging from 5% to 25% of MVC and increasing by 5% each stage, was measured. In all cases the VO2 at rest or during isometric contraction was determined from the decrease of the oxyhaemoglobin (O2Hb) signal immediately after arterial occlusion of the thigh. Repeated measurements showed no significant difference between trials, indicating that the measurements were reproducible. At rest a VO2 of 6.7 +/- 1.1 microMO2Hb.min-1 (mean +/- S.E.M.) was found, a result comparable with other studies. In all subjects a linear relationship was found between the VO2 and the level of exercise. The average slope of the regression lines of all individuals was 0.85 +/- 0.22 microMO2Hb.min-1.%MVC-1 (mean +/- S.E.M.). Inter-individual variation of the slopes was high and ranged from 0.28 to 2.29 microMO.Hb.min-1.%MVC-1, which can be explained by differences in fat percentage and in the measuring volume of the NIRS instrument. NIRS appeared to be a reproducible and reliable method for the non-invasive measurement of VO2 in human muscles. The method could be used to investigate regional differences as well as changes in time between muscle groups as a function of training.