The World Health Organisation’s (WHO) current definition of chronic obstructive pulmonary disease (COPD) is a lung ailment fundamentally characterised by persistent blockage of airflow from the lungs . In 2004 the WHO estimated 64 million global cases of COPD and later predicted COPD to become the third leading cause of death by 2030 . Among Australians, COPD was the third leading cause of burden of disease and injury behind ischaemic heart disease and stroke . Somewhat understandably, tobacco usage was listed with physical inactivity as the two leading risk factors eliciting burden of disease in Australia . Although not always the case, tobacco smoke is the leading risk factor for COPD . While the cost of COPD in Australia has not been directly estimated, respiratory disease alone accounted for AU$3.31 billon (6.3%) of the total allocated health expenditure in Australia .
Given that COPD diminishes the ability of the lungs to supply the body with oxygen, most modes of physical activity lead to breathlessness if the disease is progressed. Perceived breathlessness, or dyspnoea, leads to physical inactivity and consequently compounds the risk of burden of disease to those individuals. As a counteractive strategy, physical activity is routinely incorporated to the management of stable COPD .
Recommendations from the WHO, the American Thoracic Society, the European Respiratory Society and the Thoracic Society of Australia and New Zealand, and other professional bodies support physical activity as integral to pulmonary rehabilitation programs in public heath settings to assist individuals affected by COPD . A goal of physical activity within pulmonary rehabilitation is to improve exercise tolerance for people with COPD. During physical activity, the cardiovascular and neuromuscular systems are stressed above resting levels, which if continued over time, can improve systemic responses. Specifically, an improvement of cardiac output and cellular respiration are common after physical activity interventions . Improvement in exercise tolerance has functional benefit such as the increased ability to complete activities of daily living (ADLs).
Maintenance and improvement of ADLs is central for functional independence [6, 8]. Given that functional independence can rely on the ability to complete ADLs, muscular strength, muscular power and gait ability are considered important. Activities requiring strong and powerful muscular contraction are fundamental and include rising from a chair, climbing stairs, turning and adjusting posture, and stumbling to avoid a fall. People with COPD have less muscular strength and power than healthy age matched controls . Subsequently, this population may have poorer exercise tolerance associated with muscular weakness . As such, for people with COPD, muscular deconditioning/dysfunction is postulated to lead to poor performance of ADLs and poor exercise tolerance.
A primary objective of pulmonary rehabilitation is to combat poor muscular performance. The components of pulmonary rehabilitation vary, but include physical activity (both aerobic conditioning and resistance training), healthy lifestyle education, and nutrition counselling . Initially, pulmonary rehabilitation can be implemented at an outpatient setting, usually followed by a home-based intervention that relies mostly on the compliance of the patient. Efficacy was established after systematic review of both outpatient pulmonary rehabilitation [12–14] and home-based pulmonary rehabilitation [15–17].
During pulmonary rehabilitation, aerobic conditioning was most effective in improving exercise tolerance at intensities over 50% of peak oxygen consumption (VO2peak) [11, 18]. Although resistance training improved muscular strength , muscular power  and variables of gait , dedicated strategies for resistance training of the lower limbs lack thorough condition specific recommendation for people with COPD. A recent literature review of resistance training during peripheral muscle training reported the efficacy of resistance training for people with COPD . As such, resistance training of the lower limbs elicited appreciable gains in muscular strength for people with COPD that may carry over to performance of some ADLs . However, resistance training was conducted in conjunction with other modes of physical activity such as aerobic conditioning. The independent effect of resistance training therefore, could not be established.
Considering the statistical and scientific evidence for efficacy of physical activity to reduce burden of disease, the need for safe and valid exercise interventions for people with COPD is salient. The common modes of physical activity; aerobic conditioning and resistance training can exacerbate the disease and affect program compliance [22, 23] and may lead to reduced physical activity because of fear of breathlessness. The clinical and social merit of physical activity that can minimise dyspnoea may provide additional exercise tolerance benefit for people with COPD. Whole-body vibration may be such a mode of physical activity, and can be easily completed in the home with little skill demand.
Whole-body vibration is a mode of physical activity during which an individual stands on a vibration platform that can create acceleration predominantly in the vertical (Fz) direction. The accelerations are transmitted to the body and postulated to elicit physiological responses similar to other modes of physical activity such as aerobic conditioning and resistance training.
After WBV, increased leg muscular strength and muscular power [24, 25], oxygen consumption [26, 27], growth hormone, and testosterone levels [24, 28] were reported in healthy young and older adult populations. Furthermore, WBV may be a safe and effective mode of physical activity to improve muscular strength, body balance and mechanical competence of bone for older adults with low bone mineral density [29, 30]. A growing body of literature on the impact of WBV has included sub-optimal health populations such as cystic fibrosis , multiple sclerosis  and stroke . Yet to date, well conducted trials into the efficacy of WBV in patients with COPD are scarce in the literature.
One paper has been published to investigate efficacy of WBV to improve muscular strength and muscular power of people with COPD. In conjunction with a clinically based three-week pulmonary rehabilitation intervention, WBV may have enhanced exercise tolerance . The authors suggested that long-term studies are needed to determine optimal intensity and duration of WBV for people with COPD, though WBV seemed to be a promising new mode of physical activity . However, efficacy of a standalone WBV intervention remains unknown in outpatient and home-based settings.
The objective of the trial is to advance knowledge of effects of physical activity on exercise tolerance and functional performance of the lower limbs of people with COPD, and to test the efficacy of a WBV intervention to beneficially effect exercise tolerance and functional performance of the lower limbs without causing exacerbations. The intervention will be conducted and data collected in the home of each participant.