The aim of the study is to determine effects of passive warming up on muscle contraction force while performing maximum intensity short veloergometric test and vertical jumps. Untrained healthy males took part in both experiments within the study. Subjects (n=13) had to perform maximal veloergometric effort with different resistance (3% and 10% of their own weight) for 5 seconds during first test. Then they performed passive warming up and repeated the test. Maximal motion frequency and power output were determined. Other subjects (n=14) had to perform maximal single jumps (one with squat and one without) during second test. Then they performed passive warming up and repeated the test. Maximal set off speed, strength, power output and jump height were determined. Maximal motion frequency and maximal power output after passive warming up in veloergometric test were significantly (p<0, 05) greater than before it. Maximal set off speed after passive warming up in jumping test was significantly (p<0, 05) greater, but maximal set off strength did not differ significantly performing both types of jumps. However jump height significantly increased in both cases. In conclusion, the results indicate that in untrained subjects, passive warming up improves muscles’ power output in both experiments. Another conclusion is that passive warming up has much greater effect on contraction speed than on muscles’ strength.