Training frequency and intensity in the rehabilitation of chronic nonspecific low back pain: an exploratory review

Abstract

Introduction Low back pain is one of the most frequently occurring musculoskeletal disorders1 and it causes the highest global disability rates compared to any other condition1. Exercise therapy can improve pain and disability in persons with nonspecific chronic low back pain (CNSLBP), however optimal training frequency and intensity for rehabilitation settings are not known2.

Purpose/Aim The purpose of this review is 1) to inventory training frequencies and intensities that are used during exercise therapy in the rehabilitation of CNSLBP and 2) to evaluate their effectiveness for the improvement of pain and disability.

Materials and Methods A literature search in PubMed and Web of Science was performed. Quality analysis was performed by two independent researchers. Data extraction of following study characteristics was performed: population size, type of exercise therapy, therapy frequency, exercise intensity, and effects of the therapy program on pain and disability level. Studies were divided into categories according to following training frequencies: high (four or more sessions/week), moderate (three sessions/week), low (two or less sessions/week), or undefined training frequency. Exercise intensity was defined as a percentage of MVC or 1RM (in motor control and strength training), or VO²max (in endurance training). Studies were classified as low (>50%), moderate (50-70%), or high (>70%) intensity.

Results Twenty-one RCT’s were included. Five articles used high, 7 articles used moderate, and 6 articles used a low training frequency protocol. In 3 articles training frequency was undefined. Four studies with high training frequency found positive results on both pain and functional outcomes but did not record specific exercise intensity. One study used a moderate intensity protocol. This study did not produce significant results on pain or disability. Studies with moderate training frequency used as well high training intensity (n=3) as moderate training intensity (n=2) protocols. Both protocol variations showed significant improvements on pain intensity and disability. Two studies in this group did not define training intensity. Studies with low training frequency used moderate training intensity in 4 studies (undefined training intensity in the other 2 studies). Only, three studies found improvements on pain and disability level.

Discussion Descriptions of training intensity were not present in 10 out of 21 studies and the heterogeneity of study designs complicated comparison of results. However, positive outcomes on pain and disability are mostly seen in high and moderate intensity protocols which begs for further investigation of these training modalities.

Conclusion High and moderate training frequencies and training intensities more often result more often in the improvement of pain and disability. However, firm conclusions on optimal training intensities are impossible due to heterogeneity of study design and a lack of high quality methodological studies with a clear description of training intensity. More research is needed to investigate the effect of differences in training intensity on a CLBP rehabilitation program.