Methodological Validation of an Intermittent Shuttle Walking Protocol in the Context of Pulmonary Rehabilitation in Patients With Advanced COPD

Although previous research in the area of pulmonary rehabilitation in COPD has documented that high intensity exercise induces greater benefits than moderate intensity exercise, patients with advanced COPD patients cannot sustain sufficiently high intensities for long periods of time due to exertional breathlessness. While patients are limited by breathlessness during continuous modes of exercise, intermittent exercise is considered to be a good alternative strategy for patients with advanced COPD as it is associated with reduced exertional symptoms. Intermittent exercise consists of repeated brief bouts of physical activity at a high intensity alternated with short periods of recovery. The rationale for the implementation of intermittent exercise in healthy people and athletes has been the capacity to impose high loads to peripheral muscles without overloading the cardiorespiratory system. Working at high intensities with limited exertional symptoms enables severe COPD patients to achieve greater exercise volumes and in extend greater peripheral muscle adaptations, thereby improving exercise tolerance. International (ATS/ERS) and national (BTS) position statements for pulmonary rehabilitation recommend intermittent exercise for patients with advanced COPD. Despite the well-documented benefits of intermittent exercise, very few pulmonary rehabilitation centres in the UK employ this modality. The reason is that most of the community-based pulmonary rehabilitation programmes lack of infrastructure (stationary cycle ergometers, treadmills, rowing machines, etc.) and healthcare professionals to implement interval exercise. Hence, it is necessary to develop alternative, easily implemented and affordable, in terms of symptoms, exercise particularly for patients with advanced COPD across the community- and hospital- based pulmonary rehabilitation setting in the UK.

In the UK, field-based walking training is prescribed in the PR setting as a convenient, less resource-intensive, and highly responsive exercise modality in patients with COPD. However, in 2018, the National COPD Audit Report, reported that only 62% of enrolled patients completed a PR programme, highlighting significant drop-out rates (38%) between initial assessment and programme completion. Intense exertional symptoms during the prescribed exercise regimes was the main identified factor responsible for non-completion rates. In 1999, Revill et al, introduced a standardized, externally-paced (continuous) endurance shuttle walk (ESW) protocol as a highly responsive and repeatable assessment tool to measure endurance capacity. The ESW protocol sustained at a relatively high intensity (85% peak walking speed derived by the Incremental Shuttle Walk Test - ISWT) is commonly employed today as a walking training modality in the PR setting across the UK. However, endurance time during implementation of ESW protocol is limited to only a few minutes (5-8 minutes) secondary to intense exertional symptoms. In particular, both breathlessness and leg discomfort are considered to limit endurance time during the ESW protocol, thus suggesting that it is a highly physically demanding task for advanced COPD patients.

It therefore seems sensible to develop an intermittent shuttle walking protocol imposing sufficiently intense loads to the cardiorespiratory system and the locomotor muscles without inducing intense exertional symptoms. In turn, this would prolong endurance time and walking distance compared to the commonly implemented continuous ESW protocol. It is envisaged that an intermittent walking protocol for patients with advanced COPD will facilitate participation and successful completion of a PR programme.

Research Aims

1. To identify whether an intermittent shuttle walking protocol is associated with tolerable exertional symptoms, thereby prolonging walking distance compared to the widely implemented continuous ESW protocol in the PR settings for patients with advanced COPD.
2. To investigate the reproducibility of the distance walked during the intermittent shuttle walking protocol.
3. To explore both patients' and health care professionals' experiences of undertaking and implementing, respectively the intermittent shuttle walking and the perceived factors affecting the implementation of this protocol in the PR setting.