This thesis concentrated in physiotherapy of sub-acute low back pain (LBP) with specific trunk stabilizing exercises. Ultrasound imaging (USI) was used to measure changes in Transversus abdominis (TrA) muscle. Pain was measured with Visual Analogue Scale (VAS).

Purpose of this thesis was to examine effects of specific lumbar area exercises on pain. The exercises were carried out within an 8-week intervention period which included measurements of the Transversus abdominis muscle with USI before and after the intervention.

Thirteen subjects commenced to the study. Subjects were students at Lahti University of Applied Sciences. Before commencing to the study, subjects filled in an initial questionnaire in order to ensure there was no medical impediment for participation.

No significant changes in TrA thickness were measured. Most of the subjects received relief to LBP. Training frequency varied amongst the subjects and some experienced difficulties in conducting the exercises due to conditions. This seemed to have a negative effect on pain.

Results indicated that specific lumbar area exercises with pilates-based approach combined with lateral breathing technique have efficacy in management of LBP.