Effects of a Low-Volume, Vigorous Intensity Step Exercise Program on Functional Mobility in Middle-Aged Adults EMER P. DOHENY, 1,2 DENISE MCGRATH, 1,3 MASSIMILIANO DITROILO, 1,4 JACQUELINE L. MAIR, 5 BARRY R. GREENE, 1,2 BRIAN CAULFIELD, 1,5 GIUSEPPE DE VITO, 1,5 and MADELEINE M. LOWERY 1,6 1 Technology Research for Independent Living (TRIL) Centre, Dublin, Ireland; 2 IR5-2-F5, Applied Technology and Design Group, Intel Labs, Intel Corporation Ireland, Collinstown Business Park, Leixlip, Co. Kildare, Ireland; 3 Ulster Sports Academy, University of Ulster, Coleraine, Northern Ireland, UK; 4 Department of Sport, Health & Exercise Science, University of Hull, Hull, UK; 5 Institute for Sport and Health, University College Dublin, Dublin, Ireland; and 6 School of Electrical, Electronic and Communications Engineering, University College Dublin, Dublin, Ireland (Received 21 December 2012; accepted 2 April 2013) Associate Editor Michael R. Torry oversaw the review of this article. Abstract—Aging-related decline in functional mobility is associated with loss of independence. This decline may be mitigated through programs of physical activity. Despite reports of aging-related mobility impairment in middle-aged adults, this age group has been largely overlooked in terms of exercise programs that target functional mobility and the preservation of independence in older age. A method to quantitatively assess changes in functional mobility could direct rehabilitation in a proactive rather than reactive manner. Thirty-three healthy but sedentary middle-aged adults participated in a four week low-volume, vigorous intensity stepping exercise program. Two baseline testing sessions and one post-training testing session were con- ducted. Functional mobility was assessed using the timed up and go (TUG) test, with its constituent sit-to-walk and walk- to-sit phases examined using a novel inertial sensor-based method. Additionally, semi-tandem balance and knee exten- sor muscle isometric torque were assessed. Trunk accelera- tion during walk-to-sit reduced significantly post-training, suggesting altered movement control due to the exercise program. No significant training-induced changes in sit-to- walk acceleration, TUG time, balance or torque were observed. The novel method of functional mobility assess- ment presented provides a reliable means to quantify subtle changes in mobility during postural transitions. Over time, this exercise program may improve functional mobility. Keywords—Sit-to-walk, Walk-to-sit, Aging, Timed up and go. INTRODUCTION Mobility has been identified as the most important functional ability determining independence and health care needs among older persons. 19 Functional mobility is defined here as the ability to move by changing body position and location, based on the WHO’s Interna- tional Classification of Function, Disability and Health. 43 While functional limitations are strongly associated with aging, 8 there is considerable variability in the degree of impairment between individuals of similar age. 35 Physical inactivity may account for this, with low levels of physical activity in older adults associated with loss of mobility and independence and a reduced number of disability-free years. 33 Recently, physical activity levels were reported to be predictive of physical function and mobility in older men. 31 Addi- tionally, the metabolic cost of locomotion has been reported to be greater in mobility-impaired older adults compared with healthy counterparts. 25 This may lead to reduced tolerance and further curtailment of physical activity, potentially compounding physical decline. Exercise interventions addressing mobility predom- inantly target elderly adults, however aging-related mobility impairment has also been reported in middle- aged adults (aged 50–64 years). 29 Reactive exercise interventions, implemented after an observed decline in mobility or an adverse event, can improve function and reduce falls risk, however full restoration of function is a significant challenge. 4 In middle-aged adults (aged 51–61 years), mechanisms of recovery from mobility impairment are reported to differ from mechanisms of Address correspondence to Emer P. Doheny, IR5-2-F5, Applied Technology and Design Group, Intel Labs, Intel Corporation Ire- land, Collinstown Business Park, Leixlip, Co. Kildare, Ireland. Electronic mail: emerdoheny@gmail.com Annals of Biomedical Engineering (Ó 2013) DOI: 10.1007/s10439-013-0804-8 Ó 2013 Biomedical Engineering Society