Muscle performance enhancement in some non-orthopedic conditions: Evidence based on modified randomized controlled trials

Abstract

Muscle performance relates to a set of parameters that reflect the capacity of muscles to provide the necessary means for accomplishing a specific task. While these tasks may depend on strength or endurance, parameters such as power or impulse may frequently be the most representative entity. To enhance muscle performance, intervention in the form of training or reconditioning is necessary. A wide scientific background covers the theory of such interventions which often relate to either normal healthy subjects and athletes or to patients presenting with musculo-skeletal disorder. However muscular insufficiency is encountered in a significant number of other pathologies that are not related to orthopedic dysfunction. Interventions targeting some of these pathologies are at the center of this paper. In order to scientifically vindicate the benefit of muscle reconditioning (MR) programs the most rigorous way is by employing a randomized controlled trial (RCT) design. An RCT typically relates to a patient group (entered randomly or consecutively) which is further randomly divided into at least 3 groups: experimental, placebo and control but may often include more than one experimental group. RCT studies constitute the classical approach in pharmacological studies where experimental drugs are administered along with placebo. The effects of both are then compared to another group which either uses another drug or is not treated during the course of the experiment. Moreover, the tests are carried out using a double blind design. With respect to the effect of MR, the implementation of an RCT approach is almost impossible to realize for the following reasons. First while prescribing a placebo drug is recognized to have no effect, it is difficult to ‘prescribe’ a physical exercise that may not have any effect. Thus when comparing e.g. high intensity exercise with any other form of exercise, the latter should not be perceived as placebo. Second MR requires strict adherence to the protocol which normally takes up weeks to complete. Hence, intervention studies relating to training are much prolonged in comparison with other modalities. In addition, unlike pharmacotherapy which from the patient’s point of view is relatively easy to follow, training, in most cases means physical presence in designated places and dedication of time and physical effort. Third, in case where a ‘notreatment’ group is to be included, RCT studies relating to musculoskeletal conditions cannot be undertaken as prescribing no activity will put the patient in an immediate risk, particularly following surgical intervention. However, this may not be the immediate situation with non-orthopedic conditions. As a result RCT relating to MR has almost exclusively been applied where no direct and immediate deleterious effect could be expected. Even then, the design was not strictly based on including a placebo group, for the reason explained above, but generally consisted of comparing different protocols. As such the term used for the studies described in this paper is modified RCT, although the text will refer to RCT. The following sections will describe the use of RCT studies for assessing the benefit of MR programs in