We propose the required %MM in Japanese women as a reference value of muscle mass for the usage of maintaining the reference value of
Vo
2max proposed by the Ministry of Health Labour and Welfare of Japan. Interestingly, the calculated required %MM was not different among age groups (Table
2). Thus, we proposed the averaged required muscle mass (28.5%) as the general value for all age groups. A large portion of the subjects (68%) satisfied the required muscle mass, while with increasing age, the proportion of subjects with %MM below the required %MM increased (Figure
5). This tendency was similar to
Vo
2max, i.e., with increasing age, the proportion of subjects with
Vo
2max values below the reference
Vo
2max values increased (Figure
1). Additionally, there was strong positive relation between percentages of
Vo
2max reference values and required %MM (Figure
6). The results indicate that subjects with total muscle mass lower than 100% of the required %MM also tended to have lower
Vo
2max when compared to levels of
Vo
2max reference values. Thus, our result suggests that one of the reasons for insufficient
Vo
2max may be insufficient %MM. Women who have %MM less than the required %MM are encouraged to increase their %MM above the required %MM to achieve the
Vo
2max reference values. The required %MM can be used as an additional parameter for preventing LSRD together with the
Vo
2max reference values. The required %MM obtained in this study is practical and appropriate for most Japanese women, because it is slightly less than the average %MM of the total number of subjects. Thus, the value is an achievable goal for most of Japanese women. Although strength training is not typically included in exercise programs targeting prevention of the age-related decline in
Vo
2max or to increase
Vo
2max, it would be advisable to recommend some form of strength training as well as aerobic training especially for individuals who do not achieve the required %MM.
Several prior studies demonstrated the significance of fat free mass, muscle mass, and/or muscle function to morbidity and mortality, although there are few researches targeting women [
31‐
33]. The Japanese Ministry of Health Labour and Welfare also has admitted the importance of muscle mass and muscle function to prevent LSRD and/or mortality in EPAR2006. However practical target values have not been offered in the statement due to the lack of evidences compared to
Vo
2max. In this present study we determined the target value of muscle mass through the
Vo
2max reference values, which already has strong evidences. Although we have not confirmed the direct relation between muscle mass and LSRD morbidity and/or mortality, we believe Japanese women could aim to achieve the required %MM as one of targets for their health. Whether an increase of skeletal muscle mass would result in an improvement of exercise capacity and or reduce morbidity and mortality needs to be confirmed by future studies.
It should note that some individuals may have a large muscle mass, yet be at a high mortality risk. For example, it is well known that central obesity is one of risk factor of LSRD morbidity. Thus, it is important to remember that muscle mass is not the only important parameter but also, other risk factor should be monitored and considered together.