Objective<\/em>: to assess the ability to detect chronic nonspecific low back pain with the following indicators: proportionality of endurance time for extensor, flexor and side muscles; Sorensen test of endurance time of extensor muscles; and fatigue using surface electromyography (EMG). Also to assess the influence of gender, height and weight variables on these indicators. Design<\/em>: pilot study with a control group. Measured by three tests and EMG of individuals with nonspecific chronic low back pain and individuals without it. Reliability is measured by repetition of tests and EMG on different days. Participants<\/em>: thirteen physiotherapy students aged between 18 and 32. Seven of them have chronic non-specific low back pain and six do not. Results<\/em>: there were no significant differences between the proportionality of endurance time for extensor, flexor and side muscles between the individuals who have low back pain and those who do not. Likewise, the Sorensen test and average power obtained by surface EMG showed no differences between the two groups. Gender has proved to be a differentiating factor with respect to the proportionality values of endurance time for extensor, flexor and side muscles. Weight has had a negative Pearson correlation (r<\/em>=\u20130.61) in extensor muscle endurance time. Conclusions<\/em>: it has not been possible to distinguish between those individuals who have low back pain and those who do not with any of the indicators used. Weight and gender are variables that affect these indicators and therefore should be taken into account when assessing individuals using these tests.<\/p>\n\n