The study is executed with all 15 study subjects over three study days with one week between each study day. In order to decrease the variation of the measurement values and increase the power of the study cross-over study design will be used. The study subjects will on one of the days wear a weight vest with 10 % of body weight in the standing position, on one of the days the same study subject will wear a weight vest with 1 % of body weight in the standing position and on one of the days the same study subject will wear a weight vest with 1 % of body weight in the sitting position.