Progressive resistance training after stroke

Stroke is the leading cause of adult disability in the western world. Loss of strength after stroke (i.e., the loss of the ability to produce normal amounts of muscle force) is often extensive. Loss of strength is also the main impairment that contributes to activity limitation after stroke.

Given that, you might think that the effects of strengthening interventions after stroke would be well established as beneficial. However, previous systematic literature reviews on this topic have included studies where the strengthening intervention was quite mild in intensity; although some improvement in strength was observed, this did not carry over to an increase in activity.

A new systematic review examined only trials where the strengthening intervention was intense enough to meet the American College of Sports Medicine's definition of true progressive resistance training: a load of 8 to 12 repetitions maximum (better known as 12RM) for at least 2 sets with progressive increases of the load.

11 studies involving 370 participants were included in this systematic review. For each trial that measured multiple muscle groups, a preliminary pooled analysis of the multiple muscle groups was performed in order to generate one standardised mean difference (SMD) for each study.

This required an adjustment to account for the fact that multiple data from the same participants were being used. In order to reduce the sample size of each trial to its ‘effective sample size’, the sample size of each group was divided by the ‘design effect’. This simply meant that the review didn't need to discard relevant data by choosing just one muscle group. Neat, huh?

The review's best estimate of the effect of progressive resistance training on strength was a SMD of 0.98, which is a large effect. The confidence interval around this result (i.e., the uncertainty around that mean result) also fell within the range of a large effect - so we can be fairly certain that the strengthening interventions had a large effect on strength.

But did making patients stronger carry over into improvements in their activity?

Unfortunately, although the review's best estimate was that strengthening had a moderate effect on activity (SMD = 0.42), the confidence interval was quite wide. This means that strengthening may improve activity but we cannot exclude the possibility that it has no effect (or evenly a mildly harmful effect) on activity.

Want to read deeper into this topic? Have a look at the free full text version of this article published in Journal of Physiotherapy!