###### Abstract  
The study's objective was to identify the features of internal movement structure that depend on speed and the importance of unloading when jogging on an anti-gravity treadmill. The aim was to investigate whether the internal structure of running changes under unloaded conditions, using an anti-gravity treadmill. Twenty male competitive middle- and long-distance runners with the following characteristics participated in the study: age, 25 \(\pm\) 5 years; body weight, 67.2 \(\pm\) 8.9 kg; body height, 177 \(\pm\) 11 cm; and training experience, 9 \(\pm\) 5 years. The gastrocnemius (GC), tibialis anterior (T), quadriceps femoris (Q), biceps femoris (B), and gluteus (G) were the five lower limb muscles whose muscle activity was evaluated. Surface electromyography (sEMG) was used to measure muscle activation while jogging and running on the AlterG Anti-Gravity Treadmill. The study method involved capturing the examined muscular activity at four different speeds: 6, 10, 14, and 18 km/h. At each of these speeds, four two-minute measurements were taken with varying body weight relief: 100%, 75%, 50%, and 25% of body weight. Repeated measures multivariate analysis of variance (RM-MANOVA) [F = 3.4663 \(p\) = 0.0001] showed that as running speed increases, the muscular activity of each muscle, expressed as a percentage of maximum muscle tension (%MVIC), decreases significantly. Results indicate that running pace affects the dynamics of the reduction in muscle activity in every examined muscle. As one runs faster, the decline in dynamics becomes more intense. At the slowest jogging pace (6 km/h), the variations were almost negligible (\(\pm\)4 percentage points between 25% and 100% body weight relief) as unloading increased. However, the discrepancies reached up to 14 percentage points at the fastest running speed (18 km/h). In every muscle studied, distinctive patterns and significant dynamics at high speeds were observed. The study's findings suggest that using an anti-gravity treadmill for training can be beneficial, yet it is important to consider the significant relationships between speed and relief, as these variables could impact maintaining a proper movement pattern and running style. This knowledge may be useful when choosing the right training regimens and loads for runners recovering from injuries. Keywords:AlterG; running movement pattern +
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appropriate training methods to support physical effort focuses not only on the muscles that generate movement, but also on the respiratory muscles [10]. Therefore, it seems worthwhile to look for an alternative training method that can help minimize the risk of injuries and decrease lower limb ground reaction forces. Numerous studies are being conducted on the structure of muscle work during running and sprinting [11; 12]. One of the components of these reaction forces is the impact force, which is defined as a local maximum force observed during the heel-toe running strategy. The magnitude of the impact force can be altered by changing stride length [13], footstrike pattern [14; 15; 16], speed [17; 18], and running surface [19]. It can be eliminated completely by running in deep water, where the runner's feet do not touch the ground [20]. Until recently, weight alleviation training has been practiced in water or with the use of various types of harnesses. A person running in deep water runs while wearing specific swimming equipment, in a deep pool, without touching the bottom with their feet. When performing this type of training, the body is supported by the water buoyancy forces; thus, the athlete's body weight is reduced to almost zero. Although studies on the subject, reviewed by [PERSON] et al. [21], showed that running in deep water can help maintain performance on land, many deep water training programs have been shown to be ineffective.