Background Neuromuscular jitter is measured 1–1.5 cm away from end-plate zone in order to record single fiber action potentials (SFAP) in near vicinity of neuromuscular junction (NMJ) where they are being generated. Recording the SFAPs also near to tendon may reflect the muscle fiber size and its variance that can be prominent in myopathies. This study aimed to define how properties of SFAP and jitter changes by moving the needle from neuromuscular junction to near to tendon in myopathic patients and to compare them with the ones recorded from healthy participants. Material and methods Three healthy participants and three patients with myopathy were enrolled. SFAPs were recorded during voluntary contraction with a disposable single-fiber EMG electrode and jitters were calculated in biceps brachi muscle at 2 sites: near NMJ and 5 cm distal. Measurements from different recording sites were performed at different sessions. The amplitude, rise time, the duration and peak duration of SFAPs were measured. Comparisons were done by using mixed ANOVA model. Results Moving the needle away from NMJ did not change the calculated parameters of SFAP and jitter in both groups. The only parameter which was significantly different in myopathy patients was slightly prolongation of both SFAP duration and the peak duration which was 0.78 ± 0.03 ms and 1.84 ± 0.06 ms in patients and 0.65 ± 0.04 ms and 1.49 ± 0.08 ms in healthy participants, respectively. Conclusions Longer duration of SFAP may reflect the poor conductance of muscle fibers as an indicator for small fiber size in myopathy.