Treatment aimed at increasing physical fitness and/or activity

Many exercise programmes are aimed at increasing aspects of physical fitness such as muscle strength, muscle cross-sectional area, muscle endurance, and coordination of movements. In general, it is believed that the improvement of physical fitness and, consequently, an increase in habitual physical activity is beneficial for the LBP patient. This may also imply that reduced physical fitness and physical activity levels play a role in the aetiology of LBP (i.e. the de-conditioning syndrome). The evidence for this relationship is, however, still weak. In a Norwegian case-control study, which compared groups of chronic and subacute LBP patients with a group of healthy controls, it was found that abdominal and back muscle endurance were reduced when comparing chronic LBP patients to subacute LBP patients, and to healthy controls (Brox et al. 2005). A more recent systematic review on the longitudinal relationship between physical capacity and the risk of musculoskeletal disorders concluded that due to inconsistency in multiple studies there is inconclusive evidence for a relationship between trunk muscle strength, or mobility of the lumbar spine and the occurrence of LBP (Hamberg-van Reenen et al. 2007). Another systematic review on the association between physical de-conditioning and chronic LBP concluded that there was conflicting and limited evidence for the presence of cardiovascular de-conditioning and multi- fidus disuse in chronic LBP patients (Smeets et al. 2006).

The Cochrane systematic review on the effects of exercise therapy identified five trials in subacute populations with data available to calculate pooled estimates for pain and four trials for self-reported functioning (Hayden et al. 2005a). All trials used non-exercise comparison groups. The content of the exercise treatments of the included trials varied from extension, flexion and/ or more general exercises (Davies et al. 1979; Moffett et al. 1999; Storheim et al. 2003) to McKenzie exercises (Cherkin et al. 1998) and to graded activity interventions (Lindstrom et al. 1992; Staal et al. 2004), which are exercise interventions that follow a cognitive-behavioural approach. The pooled effects estimates for pain (i.e. 1.9 points at a 100-point scale) and functional status (i.e. 1.1 point at a 100-point scale) at short- and intermediate-term follow-up were small and non-significant leading to the conclusion that there was insufficient evidence to support or refute the effectiveness of exercise therapy in subacute LBP (Hayden et al. 2005a). In a more recent large (n=259) randomized controlled trial (RCT) by Pengel et al. physiotherapy-directed exercise was compared with advice and placebo treatment in a population of subacute LBP patients. This study showed that exercises were significantly, but only slightly, more effective for pain and functioning at 6 weeks when compared to a placebo treatment (Pengel et al. 2007).

The results of exercise treatments in chronic LBP populations are more promising than the results in subacute populations. The meta-analysis by Hayden et al. found statistically significant effects of exercise therapy in chronic LBP at short-, intermediate-, and long-term follow-up periods based on 46 studies. The pooled mean differences in improvement was 7.3 points (of 100 points) for pain and 2.5 points (of 100 points) for function at the earliest follow-up point and similar effects were found for the intermediate and long-term follow-up (Hayden et al. 2005a). The studies included were mostly conducted in healthcare settings, commonly used individually designed and delivered exercise programmes, and often included strengthening or trunk- stabilizing exercises. Conservative care was frequently added to the exercise programme, including treatment components such as advice to stay active and education, manual therapy, or even behavioural therapy (Hayden et al. 2005a). The authors of this review study concluded that exercise therapy seemed to be slightly effective in decreasing pain and improving function in adults with chronic LBP, particularly in healthcare populations (Hayden et al. 2005a). Similar conclusions were reported in the evidence review which accompanied the European guidelines for chronic LBP (Airaksinen et al. 2006). The authors found, based on a best-evidence rating system applied to 45 studies, strong evidence that exercise is more effective than general practitioners’ (GPs’) care for pain and disability reduction, and return-to-work at 3 to 6 months. Moderate evidence was found when the comparison group included passive treatments. Besides the comparison between exercise and GPs’ care or other treatments, the authors also compared different types of exercise therapies to each other (Airaksinen et al. 2006). In one of these comparisons muscle reconditioning and strengthening exercises were compared to other types of exercises. Based on the results of eight randomized studies it was concluded that there was strong evidence for muscle reconditioning and strengthening exercises being not superior to other types of exercises. In addition, one study provided limited evidence that there are no differences between aerobic and either reconditioning or conventional physiotherapy exercises (Mannion et al. 1999; Mannion et al. 2001; Airaksinen et al. 2006).

Based on studies with available data in roughly the same set of studies Hayden et al performed a meta-regression analysis alongside their meta-analysis to investigate which types of exercise therapies are most beneficial for chronic LBP patients (Hayden et al. 2005b). The conclusions of this literature study were slightly different when compared to the European guideline evidence review. Of the different types of exercise treatments, stretching exercises demonstrated the largest improvements in function outcomes and muscle strengthening exercises the largest improvement in pain outcomes (Hayden et al. 2005b). Further, the meta-regression model revealed that the effects of exercise on pain and function outcomes were greater if the exercise programme was individually designed and supervised (including home exercises), had a high dose or intensity

(>20 hours), and encompassed an additional conservative care intervention component (Hayden et al. 2005b). Although these results are interesting and seem to provide tools for daily clinical practice it should be noted that the effects found for pain and function outcomes were still not considered large enough to represent a clinically important effect (i.e. 10 and 20 points for pain and function scores respectively on a 100-point scale) (Hayden et al. 2005a, 2005b).

If exercise programmes are aimed at improving aspects of physical fitness, changes in physical fitness or performance are expected to be associated with changes in clinical symptoms or disability (Airaksinen et al. 2006). Of the 46 studies included in the European evidence review only seven studies investigated the relationships between pain and disability on the one hand, and spinal mobility/range of motion, trunk strength or trunk endurance on the other hand (Airaksinen et al. 2006). Among those studies only two studies reported weak associations between pain/disability and spinal mobility (correlation coefficient r= 0.2-0.4) (Elnaggar et al. 1991; Mannion et al. 1999) and trunk strength (correlation coefficient r=0.48) (Martin et al. 1986). Although these and other results (Airaksinen et al. 2006; Smeets et al. 2006) point out there is hardly any relationship between changes in pain and disability and direct changes in aspects of physical fitness or performance after engaging in exercise treatments, the research literature suggests that physical fitness and activity programmes are to some extent effective in chronic LBP patients. There are, however, still many questions with regards to optimal content of treatment and mechanisms of action of physical fitness and activity programmes that remain to be answered in future studies.

 
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