While exercise frequency, type, and time are relatively easy to quantify, quantifying exercise intensity is

more complex. Quantification of exercise intensity has been achieved in the domain of strength training, where intensity is routinely measured using ABT-199 the 1-repetition maximum (1RM) method (Thompson et al 2010). Aerobic training programs use intensity measures such as percentage of maximal oxygen uptake or percentage of heart rate maximum to determine the appropriate intensity for inducing a cardiovascular training effect (Thompson et al 2010). The Borg rating of perceived exertion scale was first developed as a measure of aerobic exercise intensity (Borg 1982) and more recently has What is already known on this topic: Exercise programs designed to challenge a person’s balance can improve balance ability in older adults. Exercises are normally prescribed by defining the frequency, intensity, type, and duration of exercise. Exercise needs to be performed near the limits of an individual’s capacity to induce a training effect. What this study adds: Although numerous trials of balance exercise interventions in older

adults have been conducted, none has quantified the intensity of the challenge to the individual’s balance system. No psychometrically validated tools exist to measure the intensity of the challenge to an older person’s balance system. In determining the optimum level of challenge of balance exercises, recommendations commonly relate to the difficulty of the balance task, rather than to the intensity of the activity relative to the ability of the individual (Thompson et al 2010, Tiedemann et al Screening Library in vitro 2011). Therefore, although it is known a person is performing one task that

may be more difficult than another, it is not clear how to quantify the challenge of that task to the balance capability of that individual. Specialist practitioners in the field of falls and balance have reported being unable to identify an ideal balance exercise intensity prescription method, other than to say that the balance exercises prescribed need to be challenging (Haas et al 2012). Given that there are four factors used to prescribe exercise, if one factor is missing or measured inconsistently, optimal prescription dosage is confounded. To date, there has tuclazepam been no systematic investigation of whether or how the intensity of balance exercise prescription has been determined in trials of balance rehabilitation programs. The research questions for this review were therefore: 1. How has balance exercise intensity been reported and prescribed in trials of balance exercise interventions? A three-phase process was used to identify articles appropriate for inclusion in this review. In the first phase, the lead investigator (MF) conducted a search in December 2011 to identify all systematic reviews published between 2006 and 2011 that included balance exercise interventions.