1 Introduction

It is estimated that in 2010 there were 202 million people suffering from Peripheral Arterial Disease (PAD). From 2000 to 2010 there was an increase of approximately 23.5% of people with PAD, 35% of which were people over 80 years old [1]. With the increasing worldwide ageing of the population, it is imperative to implement measures to properly supervise people with PAD [2].

The main symptom of PAD is intermittent claudication, which is defined as a muscle pain that occurs in the leg and is caused by exercise and relieved by rest [3]. It is estimated that between 20 to 40 million people worldwide suffer from this symptom [1], affecting the majority of symptomatic PAD patients [4].

PAD is known to cause the blockage of arteries which affects the blood flow to the lower extremities, consequently affecting the person’s ability to walk [5]. In extreme cases, PAD can cause ulcerations or gangrene, leading to amputation of a leg [6]. The quality of life of people suffering from PAD will progressively deteriorate [7]. A recommended treatment for people with PAD is the practice of supervised physical activity [8]. It is important to understand how exercise can improve the quality of life in terms of health.

The researchers Blair et al. proved that exercise can delay the mortality caused by cancer or cardiovascular diseases [9]. The study conducted by Warburton et al. also proved the aforementioned statement, adding that chronic diseases such as diabetes, obesity and depression can be prevented with the regular practice of physical activity (PA) [10]. It is essential to define what constitutes the necessary amount of physical activity for a person to stay healthy.

The guidelines published by the American College of Sports Medicine and the Centers for Disease Control and Prevention provide important recommendations for people to follow, in order to maintain a healthy lifestyle [11]. These recommendations are based on promoting physical activity, suggesting that all healthy adults should perform at least 30 min of physical activity with moderate intensity, five days per week. The exercises recommended are walking and jogging. The fulfillment of these guidelines could reduce unhealthy weight and the risk of chronic disease. The research conducted by Hallal et al. [12] reached the conclusion that roughly 30% of adults in the world do not fulfill the physical activity recommendations provided by Haskell et al. [11]. Regarding PAD, a study conducted by Lauret et al. [13], involving 94 patients with PAD, assessed the extent to which they fulfilled the recommendations for physical activity, as proposed by Haskell et al. [11]. To evaluate the participants, they had to wear an accelerometer during 7 consecutive days to measure their physical activity. It was concluded that only 46% fulfill the physical activity recommendations.

There are currently several methods and techniques to promote and evaluate exercise in PAD. They can be divided into two main categories: supervised exercise programs (SEP); and home-based exercise programs (HEP). The SEP include treadmill walking [14] and a 6-min walking test [15]. These tests need to be done in a hospital environment, which does not reflect real-world conditions, when compared to a neighborhood walk for instance. In addition, it has higher costs to the patients [16]. Makris et al. elaborated a review based on the SEP and HEP in PAD and suggested that the HEP could be a cost-reduction alternative to SEP by using pedometers to motivate and supervise PAD patients [17]. In HEP, it is also possible to use the global positioning system (GPS) to supervise the walks of people suffering from PAD [18].

The research conducted by Regensteiner et al. reveals that in PAD, hospital SEP provides better results for improving the health condition of patients with PAD, particularly when compared to unsupervised HEP [19]. This study also highlighted that the hospital exercise programs were not accessible to all patients, so many health professionals recommended the unsupervised home exercise program. A solution to mitigate this problem is to remotely supervise the patient’s physical activity at home.

In order to remotely supervise people’s physical activity, it is possible to use objective or subjective methods. The study conducted by Lin & Moudon compared the effectiveness of measuring people walking using both objective and subjective methods. Objective methods referred to the collection of data on the field using technological devices, while subjective methods assessed people’s perceptions of their walks using questionnaires. In PAD it is possible to apply questionnaires to measure the person’s walking ability [20, 21]. It was concluded that the objective methods were more effective than the subjective methods [22].

Nowadays it is possible to monitor the patients’ physical activity at home using technological equipment. Some studies achieve this by using a system to supervise the personal wellbeing and by collecting data about the patient’s physical activity, e.g., the step count or the type of activity executed by the user [23, 24]. These techniques have been studied and used by the authors for health and accessibility purposes [25,26,27,28,29], as well as the pervasive approach for collecting data e.g., gamification strategy for user engagement [30,31,32].

This work will conduct a review of articles that report the creation of systems with the objective of supervising a person using technological devices, which is done to help health professionals keep track of the patients’ wellbeing through their physical activity data.

2 Methodology

In this review, the objective is to search for technologies that can supervise or monitor people suffering with PAD in terms of their physical activity at home or in the community. The reason is that supervising exercise can improve the quality of life in PAD patients [8]. As reported in the Introduction section, Home Exercise Programs can be a cost-effective solution [16], so in this review we wanted to search for technologies such as mobile and GPS which allow people with PAD to have supervised exercise at home or in their community. The database chosen was Google Scholar, using 2008 as the base year, and the query with Boolean operators was “peripheral arterial disease” AND (mobile OR “global positioning system”) AND (home OR community) AND (supervise OR monitor) AND (exercise OR “physical activity”) AND technology. After applying the exclusion criteria, the results were the following:

  • The first query returned 691 publications;

  • The duplicates were removed (4);

  • The publications to which the authors couldn’t get access or which were not in English were removed (56);

  • The publications that were not scientific articles were removed (89);

  • The reviews (15) and the surveys (3) were removed;

  • After an analysis of the title, the abstract, or if necessary the whole article, the articles that did not focus on people with PAD were removed (460), as well as the articles that didn’t include supervision of physical activity or exercise (46).

After applying this methodology, the final results returned 18 articles related to peripheral arterial disease, which included mobile or GPS technology to supervise the physical activity or the exercise of people with PAD.

3 Results

The articles retrieved from the review were grouped as follows: twelve were based on the accelerometer; six were based on GPS; two were based on a smartphone application; and another one, was based on a smartwatch app.

The articles that were based on the accelerometer [13, 33,34,35,36,37,38,39,40,41,42,43] consisted of giving the accelerometer to people with PAD, frequently integrated in an Activity Monitor (AM), with the objective of measuring their physical activity for seven consecutive days. These tests had the goal of determining if the accelerometer could improve the health status or walking ability in people suffering with PAD. From these articles, seven used treadmill tests to complement the results, while four used questionnaires to obtain the subjective measures from patients on the parameters of the walk, such as distance or time. It is important to highlight that the treadmill was used in nearly 60% of the articles based on the accelerometer, revealing that it currently still counts as a frequent tool to measure the walking progress of PAD patients, confirming some articles in the literature, which refer to the treadmill tests in PAD is the gold standard [44]. From this review it was found that the data collected from accelerometers is significantly correlated with the data collected in the treadmill [35, 42] and that the activities, identified by the activity monitor (AM) with the accelerometer, presented good results. However, the research conducted by Gardner et al. [37] revealed that the results obtained in the hospital, using tools like treadmill tests, get better results in improving walking ability, especially when compared to the data collected in AM.

The articles that were based on GPS [45,46,47] consisted of logging the users’ location and supervising the user for one hour in an outdoor environment, and then repeating the test with at least one month interval. The data collected is: the distance, the number of stops and the speed of walking. In the three articles, only one compared the collected data with the treadmill. One article argued that GPS can be a useful tool to supervise the exercise program and that it correlated with the subjective questionnaires that were used for collecting feedback from the users [46]. Another article reported that GPS data correlated with the treadmill tests [47], while another one confirmed that the data collected confirmed the initial hypothesis of that study [45]. In all three articles about GPS, the data correlated with their hypothesis or methods, proving that GPS can be a useful tool to assess a person’s activity.

The article related to using a smartwatch application [16] supervised the patients’ steps and gave daily pre-defined notifications for people to meet their exercise goals. They concluded that the people with PAD significantly improved their walking ability.

The articles related to smartphone applications [48, 49] were both in development. The research conducted by Fokkenrood et al., described a web portal to connect health professionals, personal trainers and PAD patients, with the aim of supervising and motivating PAD patients [48]. Also, this research also reported the development of a mobile app to calculate the distance between GPS updates. The approach described by Reis et al. [49] revealed that with the implementation of a web service (a mechanism to facilitate remote communication with the database), a smartphone application and a web portal it was possible to supervise and monitor patients with PAD. In this approach, it is advisable for the development to focus on user-centered designs to solve some problems related to user usability, which might be possible by making an application that can be accessible to the target population and capable of automatically synchronizing the collected data with the webservice.

Table 1 shows an overview of the results retrieved from the review on technologies that can help supervise exercise in PAD.

Table 1. Overview of the articles included in review
Full size table

Table 1 shows an overview of the review carried out, with some of the parameters such as the methodology, the assessment (autonomous remote supervision, questionnaires about walk details, treadmill) and some observations regarding each article. The autonomous remote supervision is the mechanism to synchronize the collected data automatically, without the need for the patient to deliver the equipment to the researcher or the health professional.

4 Discussion

In the technologies based on the accelerometer, many used equipment that was small and could easily be attached to the body. There were some accelerometers that needed calibration specifically to the person that was wearing them. Some articles reported that the collected data from this equipment could be correlated with other tests such as the treadmill [35, 42], used to assess the walking capacity of PAD patients. However, there was one study [37] which proved that the tests conducted in a hospital get better results compared to the accelerometer equipment. The reason the hospital supervise exercise program (SEP) improves walking ability might be because of the continuous presence of a health professional who can provide advice and support to the patient. To replicate this effect, it is necessary for the in-home exercise program (HEP) to include remote supervision of people with PAD, with the health professionals supervising the patients at home and even sending notifications to remind the patients to achieve their exercise goals. The patient would have to deliver the accelerometer to the health professionals for them to retrieve the collected data.

All the GPS articles reported in this review could be correlated with their hypothesis or method, proving that this tool could be useful to supervise the patients’ exercise. Nevertheless, it presented some disadvantages as well, such as the fact that they only work in outdoor environments and, like the accelerometer, the patients with PAD would have to deliver the equipment to the health professionals for them to retrieve the collected data.

In most of the reviewed articles, the autonomous remote supervision was not addressed. That is because in most articles, the collected data had to be delivered by the patient to the hospital, which could discourage the patients to maintain the exercise program. There were two articles that approach these issues, though their solutions were still in development [48, 49]. The method related with autonomous remote supervision could resolve the problems related to motivation of people suffering from PAD [37], while still being a cost-effective solution. With this method it is possible for health professionals to supervise their patients at home and to schedule targets or objectives for the patients to maintain their health status.

5 Conclusion

In this article, a review of technologies was conducted with the aim of helping health professionals to supervise the exercise or physical activity in people suffering from PAD. Most of these people have walking limitations that will deteriorate with time. To mitigate and reverse this outcome, it is essential to encourage and to monitor them to perform exercise regularly. The SEP programs in hospitals are expensive and don’t replicate the community’s conditions, so a better alternative is to use technologies to help in the supervision of exercise at home.

From the articles reviewed, the most frequent technology found was the implementation of accelerometers, frequently in the form of activity monitors. The use of this equipment is highlighted by the many studies that validate this technology for PAD patients. They also demonstrate certain disadvantages related to the initial calibration specific to each person, as well as the need for someone with technical knowledge to retrieve the data. In this review, some articles were also found which describe tests using GPS to track people’s locations in order to calculate the distance. This equipment has the same disadvantage as the accelerometer with regards to the technical knowledge needed to retrieve the data.

A better solution might be to implement a monitoring system and to perform remote supervision in people with PAD, simplifying the process of retrieving the collected data. This can be done with an application on a mobile device with the capability of synchronizing the collected data via the Web, so that health professionals can keep track of the status of the patients walking ability. These solutions were found in two articles which reported this approach as still in development.