Persons infected with HIV are often frail, depressed and live a sedentary lifestyle for which conventional exercise is too taxing. Here, we present an exercise protocol that ameliorates aspects of frailty in HIV-infected persons. An exergame integrating cognitive control was developed using biosensors that measured balance, weight-shifting and obstacle crossing.
Approximately 1.2 million people in the United States live with HIV infection. Medical advancements have increased the life expectancy and this cohort is aging. HIV-positive individuals have a high incidence of frailty (~20%) characterized by depression and sedentary behavior. Exercise would be healthy, but due to the frail status of many HIV-positive individuals, conventional exercise is too taxing. The aim of this study was to evaluate the effectiveness and acceptability of a novel game-based training program (exergame) in ameliorating some aspects of frailty in HIV-infected individuals. Ten older people living with HIV were enrolled in an exergame intervention. Patients performed balance exercises such as weight shifting, ankle reaching, and obstacle crossing. Real-time visual/audio lower-extremity joint motion feedback was provided using wearable sensors to assist feedback and encourage subjects to accurately execute each exercise task. Patients trained twice a week for 45 min for 6 weeks. Changes in balance, gait, psychosocial parameters and quality of life parameters were assessed at the beginning, midterm and at conclusion of the training program. Ten patients completed the study and their results analyzed. The mean age was 57.2 ± 9.2 years. The participants showed a significant reduction in center of mass sway (78.2%, p = .045) during the semi-tandem balance stance with eyes closed and showed a significant increase in gait speed during a dual task motor-cognitive assessment (9.3%, p = .048) with an increase in stride velocity of over 0.1 m/sec. A significant reduction in reported pain occurred (43.5%, p = .041). Preliminary results of this exergame intervention show promise in improving balance and mobility while requiring older people living with HIV to be more active. The exergame can be continued at home and may have long term as well as short-term benefits for ameliorating frailty associated with HIV infection.
The implementation of effective antiretroviral therapy (ART) for human immunodeficiency virus (HIV) infection has resulted in infected persons living to an older age.1 The mean age of HIV-infected patients is increasing2 and it is predicted that 73% of individuals infected with HIV will be aged 50 years or older by 2030.3 Persons aging with HIV infection may have "accelerated aging" with an earlier than expected occurrence of many diseases of aging including frailty and high risk of falling.4-8 Similarly, persons with HIV infection have a high prevalence of comorbidities including cognitive decline, peripheral sensory damage (i.e., neuropathy) and pain leading to physical impairments and elevated fall risk.9 Approximately 75% of HIV-infected persons receive at least one prescription medication in addition to ART including some prescriptions associated with high-fall risk (cardiovascular and psychoactive medications).10 HIV infection is associated with neuropathy, which is highly prevalent among older adults with HIV.11 In addition, HIV could lead to cognitive decline and thus impact the mobility and risk of falling leading to loss of independence and poor quality of life.12
A few studies demonstrate the benefits of exercise in patients with HIV, e.g., improving balance, pain perception, perception of life satisfaction, reducing functional limitations, and improving the quality of life.13-18 However, conventional exercise may not be appropriate for many older HIV adults due to risk of fall, lost joint perception, reduced joint mobility and overall frail status. These features may limit exercise performance particularly in those suffering from neuropathy.19,20 HIV infection can be associated with loss of lean body mass which may be related to difficulty in exercising, poor nutrition, widespread pain, metabolic disturbances, and lipid abnormalities,21 all contributing to an inability to participate in conventional exercise.15 In addition, with a 20% incidence of frailty6,7 many exercises will not be appropriate for the frail, older adult. Thus, several factors need to be considered during development and implementation of exercise for older HIV adults including compensation for lost joint perception, improving motor-cognitive performance, controlling the intensity of training to avoid overtaxing and finally, personalization of exercise by adapting exercises in their intensity and timing to account for physical limitations. Exergaming and virtual-reality techniques have been evaluated for training of motor control in the elderly22-24 with benefits including concordance of visual and proprioceptive information, salient feedback from joint movement as well as activation of motor related areas in the brain.24-26
In this study we evaluated the effectiveness and acceptability of tailored sensor-based interactive exercises of the lower extremities with real-time feedback and their effect on improving postural stability and activities of daily living in HIV-infected older adults. The exercise training specifically focused on ankle joint and lower extremity range of motion with both cognitive and motor components. We hypothesize that exercise training through an interactive interface with real-time visual joint movement during exercise will not only improve postural stability, but may ameliorate features of frailty, if not frailty itself.
The study was approved by the Institutional Review Board of the University of Arizona. Participants provide their signed consent to participate.
1. Recruit HIV-infected Participants
2. Assess the Frailty Status of the Participants by the method of Fried et al.28 with slight modifications for the HIV population29
3. Begin Training Intervention
4. Trainer Measures and Records All Interventions
5. Remunerate Subject For Their Time
6. Perform Statistical Analysis on All Subjects and Their Measured Responses to the Tasks
Ten adult older people living with HIV (Age: 57.2 ± 9.2 years, BMI: 27.0 ± 2.8) underwent 6 weeks (twice a week) training and successfully completed all sessions and their results were analyzed..
The participants showed a significant reduction in center of mass (CoM) sway (78.2%, p = .045) during the semi-tandem balance stance with eyes closed, one of the more difficult positions for this population subset (Figure 3). Participants show a significant increase in gait speed during a dual task motor-cognitive assessment (9.3%, p = .048) with an increase in stride velocity of over 0.1 m/sec that achieved statistical significance (Figure 4). The pain questionnaire also showed a significant reduction in reported pain (43.5%, p = .041), an important indicator for quality of life assessment (Figure 5).
Those participants who indicated depression (> 16) at baseline, as assessed by the CES-D questionnaire, reported a trend of slower gait speed during single task walk (<1.3 m/sec, R2 = 0.2911). This group with slower baseline gait speed showed a trend for greater improvement in delta gait speed for pre vs. post-intervention (R2 = 0.3906). Another trend was observed relating change in gait speed to frailty status. Non-frail patients reported reductions averaging -0.08 m/sec in their gait speed during initiation and steady state phase at follow-up from baseline (p = 0.125) whereas, patients classified as pre-frail due to depression at baseline reported improvements averaging .09 and .082 m/sec in their gait speed during initiation and steady state phase, respectively, post-intervention versus baseline (p = 0.143).
Figure 1: Subject Performing Motor-cognitive Ankle Reaching Task with Support of Walker. Subject is viewing a virtual representation of himself (avatar) on the screen. His motion is in response to the auditory and visual feedback from the screen in front of him provided by the biosensors seen at the ankles, thighs and waist. The individual gave written consent to being photographed.
Figure 2: Subject Performing Obstacle-crossing Task with Support of Walker. The subject sees only his lower limbs on the screen and alternates moving his legs to avoid hitting the virtual obstacle displayed on the screen. The individual gave written consent to being photographed.
Figure 3: Improvement in Center of Mass Sway during a Single Stance Pose, Pre- and Post-intervention. The subject demonstrates a reduction in movement, i.e., sway, indicating improved balance. Error bars represent SEM.
Figure 4: Improvement in Stride Velocity, Pre- and Post-intervention. Stride velocity is measured in units of m/sec. A faster velocity is indicative of better physical performance. The error bars represent SEM.
Figure 5: Improvement in Pain Assessment, Pre- and Post-intervention. This is obtained from a self- reported questionnaire noting a reduction in daily pain (on a scale of 0-10). The error bars represent SEM.
Session | Activities Performed | Time | |
Baseline | Balance and gait exercises | Total time 20 min; each exercise (6) and balance poses (6) are 2-3 min in duration | |
Session 1 | Balance and ankle reach exercises | Total time 25 min; balance poses (4) are 2-3 min and 3 sets of 3 of ankle reaching task, each set is 5 min | |
Sessions 2-7 | Balance, ankle reach and obstacle crossing exercises at 5% and 10% height of subject | Total time 35 min; obstacle crossing, each height is 5 min | |
Midline | Repeat baseline | Total time 20 min; each exercise (6) and balance poses (6) are 2-3 min in duration | |
Sessions 9-12 | Same as 2-7 sessions plus motor-cognitive ankle reach and obstacle crossing at 15% and 20% height of subject | Total time is 45 min; additional 10 min for each of the added two heights | |
Follow up | Repeat baseline | Total time 20 min; each exercise (6) and balance poses (6) are 2-3 min in duration |
Table 1: Training Sessions and Exercises.
We have found that among frail HIV patients, 100% were depressed as measured by the CES-D scale; 30% are mildly depressed and 70% have a major depressive disorder.7 It is important to stress that in a non-frail HIV patient population, depression was very common as well with 38% being depressed. Although all depressed patients availed themselves of counseling and anti-depressive medications they remained depressed, thus contributing to a pre-frail (subject having 1 or 2 of the 5 criteria of Fried for frailty28 or frail state, 3 or more criteria). Because depression is so prevalent among HIV patients we are attempting to ameliorate the mood disorder and frailty with novel interventions such as described here. We are employing exercises requiring cognitive control that involve balance and gait, features in HIV-infected persons that are often compromised in the pre-frail and frail state. The exergaming described here is very low impact in the physical sense and thus, has little risk for frail patients. It is important that all of the exercises and sessions are completed in sequence since they become increasing difficult, particularly in the sphere of cognitive input. For example, in the later sessions memorizing the sequence of moving the cursor by moving the ankle is important for successful completion. It is critical that each task is completed in order for accurate data to be recorded and therefore, meaningful comparisons can be made between subjects.
Virtual reality gaming, such as Nintendo Wii Exergames, can improve physical function, cognition and psychosocial outcomes in the elderly.43 One study of twenty, 60-95 year-old individuals included depression screening. This study did not demonstrate any significant difference in Geriatric Depression Scale scores measured at the beginning and the end of the study. The intervention lasted for 6 weeks and consisted of 3 days a week, 35-45 min sessions with 3 balance games.44 Although the exercise regimen in that study is similar in length to that used in our study, the commercial games require more vigorous movement than the exercises in our study. Furthermore, the exercises in our study are calibrated to each unique individual, whereas, the commercial exergames are intended for use by anyone in the general population and thus, do not have the precision and accuracy that the exercises reported here possess.
Exercise alone has been shown to prevent the onset of depression.45 Exercise can ameliorate depression but, its effects are not long-lasting.46 The intervention in HIV patients reported here involves virtual reality exercises calibrated to each unique patient. Cognitive input in the form of choosing how to change the patient's virtual representation, the speed of action, direction and magnitude are under the subject's cognitive control. Although similar to commercial exergames the methods differ in important ways. For example the commercial games are standardized for use by large numbers of individuals whereas with our protocol measurements are individualized for each patient, biosensors being employed at various body sites which make for precise and accurate measurements. Preliminary data shows promise for this form of technological intervention in making improvements in the depressive and frailty state of HIV-infected individuals. The preliminary results are promising for balance and gait improvements in the HIV population and the effectiveness of this novel wearable sensor virtual-reality based balance training program. Gait is one of the measurements used to assess for frailty28 and balance contributes to the character of gait. The significant reductions in CoM sway and increases in gait speed are promising for an intervention of this duration and shows the potential to ameliorate aspects of frailty.
With ongoing participation we hope to see continuing improvements in overall quality of life of the HIV patient in psychosocial parameters (i.e. pain, depression) as well as objective measures (i.e. frailty status, gait speed, CoM sway, etc.). We believe that along with the physical improvements in balance and gait there could be an associated lower risk and fear of falling. Also, with reduction of pain and encouragement of physical activity and cognitively challenging exercises through introduction of this intervention we hope to see improvements in daily physical and social activity, and a lessening of the depressive state. The study was preliminary but it shows that the intervention may be effective in addressing some aspects of frailty and was well accepted by the subjects. The duration of the intervention was short and will require follow-up at later dates to assess the true value and benefits. One major drawback to subjects participating in the study is the large time commitment on the part of the subjects. Individuals who were interested in the participating were often unable to meet the time commitment needed to complete the exercises (twice a week for 6 weeks) and many could not afford the travel expenses. We are planning on refining the exercises and perhaps reducing the time required for the sessions.
This study provides promising preliminary results for the use of this novel wearable sensor virtual-reality based balance training exercise program in a clinical or home setting to improve postural balance and gait. This study also explores the trend that those who benefit the most or have the greatest improvement in these objective modalities are the depressed or pre-frail individuals. This could improve their overall quality of life by reducing the fear of fall and fall risk and encouraging and increasing overall physical activity.
The authors have nothing to disclose.
Funding for this research was provided by intramural funds from the Division of Infectious Diseases.
Handhold | Optional; for very frail patients | ||
2 sensors: LegSys and Pamsys | Biosensics, Cambridge, MA | ||
Computer screen | Placed in front of the subject | ||
Program of exercise protocols | These display objects and avatar on the screen | ||
Large clinic examination room | Needs to accommodate the activities of subject and trainer | ||
1 older HIV-infected subject | |||
1 trainer |