This review therefore provides empirical and objective evidence of a serious gap in this wide field of research and clinical practice. Of 148 randomised trials reporting

balance exercise interventions, none reported a validated measure of balance exercise intensity. Instead, the most common approach adopted was to describe of taxonomy of task difficulty that trial participants progressed through as they performed activities of increasing difficulty (Chin Navitoclax A Paw et al 2004, Chin A Paw et al 2006, Davison et al 2005,Englund et al 2005, Hauer et al 2001, Hauer et al 2002, Helbostad et al 2004, Netz et al 2007, Sjösten et al 2007, Tinetti et al 1994). One could argue that this approach is sufficient to challenge participant balance capabilities and induce an overload effect. However, this approach provides no indication of how difficult the individual performing the task found this at the time. There is an underlying

assumption that all individuals have the same balance capacity and are consistently challenged by the introduction of a ‘subsequent task’ in the hierarchy. This is analogous to a strength-training program where participants were asked to perform a leg press against resistance of 5 kg, 10 kg, and 15 kg weights in successive weeks. Although we know the resistance is increasing, we do Pifithrin-�� in vivo not know what percentage of 1RM these weights represent for the participant. For a frail older adult this may be a very difficult activity, but for a younger, fitter individual it may not, and it would not be possible to monitor the exercise intensity level in either individual in terms of a proportion of their capability. Of the few studies that purported to report balance exercise intensity explicitly, intensity was represented inaccurately. In other words, authors used other parameters

as surrogates for intensity. Some authors reported balance exercise intensity in terms of time spent balance training. For example Silsupadol et al (2009) state that the ‘duration and intensity of this training [was] chosen based on previous studies showing that 10-hour to 12-hour balance training and 1-hour to 5-hour dual-task training programs were effective’ Mannose-binding protein-associated serine protease (p. 382). Similarly Rubenstein et al (2000) reported an increase in balance exercise difficulty by increasing the time spent training from 5 min to 15 min over the 12 weeks of their program, and Wolf et al (2003) who report increasing the intensity of their Tai Chi intervention by increasing duration of sessions from 60 to 90 min over the course of a year. Authors also reported an increase in task difficulty as a proxy for balance exercise intensity. This was primarily done with exercise programs that progressed through standardised levels of difficulty (Davison et al 2005, Tinetti et al 1994) or with reference to task taxonomies (Helbostad et al 2004, Silsupadol et al 2006), for example Gentile’s taxonomy of movement tasks (Gentile 1987) or the task manipulations described by Geurts et al (1991).