The purpose of this study was to establish the influence of temperature on quadriceps femoris muscle force, contraction and relaxation time, low frequency fatigue and muscle recovery after performing high-intensity exercise. Healthy untrained men (age 21-30 years, n = 9) gave their informed consent to take part in all experiments within the study. A high voltage stimulator (MG 440, Medicor, Hungary) was used for electrical stimulation; quadriceps muscle was stimulated through surface electrodes (9 x 18 cm) padded with cotton cloth and soaked in saline solution. The following data were measured: the force of quadriceps muscle, aroused by electrical stimulation under 1 Hz (Pt), 20 Hz (P20) and 50 Hz (P50) frequencies (the duration of each electrical stimulation series was 1 second) and maximal voluntary contraction force (MVCF). Hot water (44-45 degrees C) bath was used for muscle heating. Blood lactate concentration was measured before exercise and after 5 min. and 1 hour after performing high-intensity exercise. Two experiments with two months recreation time were carried out. The following conclusions were received: even though muscle heating increases the speed of dominating lactate in blood and increases the muscle force caused by low and high stimulation frequency, it does not influence the recovery properties of muscle contraction and relaxation during 24 hours after performing high-intensity exercise.