Acute care physical therapists regularly use therapeutic exercise to target body structures and functions as a supplement to or even replacing activity-based interventions. Interestingly, little is known regarding the mechanism of action explaining how exercise enables future activity and participation. One potential mechanism of action is the repeated bout effect (RBE), which is the phenomenon that a single bout of exercise provides protective adaptations for future exercise/physical activity.
To perform a systematic review examining the exercise parameters required to induce the RBE and explore how the results apply to acute care physical therapists.
Academic Search Complete, CINAHL, MasterFILE Premier, MEDLINE, PsycINFO, and SPORTDiscus.
The search included articles appearing before January 1, 2017. The following were the inclusion criteria: human subjects, randomized controlled trial design, published in English, treatment and control group engaged in exercise, lower extremity exercise intervention, and pre- and postintervention creatine kinase blood marker measurement.
Data Extraction and Quality Assessment:
Three reviewers extracted data and then assessed the methodological quality of the included articles.
Of the 1780 potential studies, seven were included. The RBE can be induced with exercise that includes an eccentric component, as well as with maximal voluntary isometric contractions at elongated muscle lengths. Concentric-only exercise does not induce the RBE and could instead blunt it. Stretching does not induce the RBE; however, it does not blunt it.
The RBE enhances a person's tolerance for future exercise/physical activity. Consequently, the use of exercise to induce the RBE would be advantageous during initial and subsequent acute care physical therapist interventions. Future research is needed to specifically address the precise dose needed to induce the RBE in middle-aged and older adults, those with acute and chronic diseases, and women of all ages.