The inflammation of the proximal muscle of the forearm muscles was commonplace. Like most tendon inflammation, it is conservatively often treated by the use of eccentric contraction. Recent studies indicate possible positivist activity of heavy slow resistence training. However, they have not been studied in populations with the inflammation of the tendon in the elbow area. The aim of this paper is to determine the difference in the effect of eccentric contractions and slow derived isotonic contractions with submaximal load in the rehabilitation of persons with lateral epicondylitis. The sample of respondents consisted of 16 people randomly divided into 2 groups. The control group carried out eccentric contraction, and the experimental group conducted heavy slow resistence (HSR) training. During the planning of kinesitherapy protocols, findings from previous studies were used, and subjects from both groups conducted exercise 3 times a day in a 10-day period. Movement range variables (angle of dorsal flexion, palmar flexion angle, angle of flexion and elbow extension, as well as pronation and supination), subjective pain assessment (VAS / NAS), and strength of hand were measured. Both groups of respondents based on the t-test for dependent samples achieved statistically significant results compared to the starting point of measurement. This has been shown that both exercise methods are useful in treating overstatement syndrome. Progress in variables relative to the initial measurement between the groups was obtained by double-factor analysis of variance with repeated measurement of factor time. Statistically significant differences were obtained in SUPINATION variables (p = 0.03) and NAS scales of pain (0.0456). The experimental group performing HSR achieves statistically significantly better results in comparison to the control group that scores statistically significantly better in the NAS variables, achieves a lower score, but as this variable is reversed, the smaller score is a better result and indicates a lower pain. The main conclusion of the study is that both groups of people achieve approximately equal results with respect to initial measurement, and the experimental group takes less time to perform the exercises. Also, the subjects of the experimental group compared the control group with a significantly better result in the SUPINATION variables. It is especially important to take into account the fact that in people with lateral epicondylitis the supine movement is extremely painful.