It is well known that the use of assistive devices, such as cane or walker, slows the walk-ing velocity and increases the energy demand of walkwalk-ing.159,160 The energy expenditure for walking with different assistive devices, from the highest to the lowest, has been reported in the following order: walker > crutches > cane or crutch > no device.161,162 People who require a walker for walking usually have a higher degree of impairment, which might explain the higher energy requirements in their walking compared to those who walk with other devices, or without a device. Walking with a rolling walker was found to require lower energy expenditure than walking with a pickup walker.163 Among different weight-bearing status and assistive devices, walking with alternating bilateral partial weight bearing, or unilateral partial weight bearing required 33% more energy than normal walking, and walking with nonweight-bearing status required 78%
more energy than normal walking.164 TABLE 2.8
Oxygen Consumption and Self-Selected Walking Velocity in Selected Pulmonary and Cardiac Patients
References Subjects
Oxygen Consumption
(mL/kg/min) SSWV (m/min) Menard-Rothe et al.151 End-stage emphysema —
Male 44.5 ± 15.0
Female 39.6 ± 12.3
Marconi et al.154 Peripheral artery disease
11.8 ± 2.3 53.33
Normal subjects 8.4 ± 0.6 53.33
TABLE 2.9
Measured Energy Expenditure in Some Activities of Daily Living in Cardiac Patients
Task Measured METs ± SD Compendium2 (METs)
Vacuuming 3.3 ± 0.7 2.5
Bed linens 3.0 ± 0.6 2.5
Groceries 3.1 ± 0.5 2.5
Laundry 2.5 ± 0.4 2.0
Treadmill (2.6 mph) 3.4 ± 0.3 3.0 (2.5 mph)
Source: Adapted from Skemp, K.M., et al., Clin. Exerc. Physiol., 3, 213, 2001.
2.5.2 WHEELCHAIR PROPULSION
People with disabilities often use wheelchair for daily mobility, longer distance of transportation, or sports activities. Manual wheelchair propulsion requires good muscle strength of the upper extremity, trunk control, and physical capacity. The metabolic demand for driving a wheelchair is similar to doing an arm crank exer-cise, but with a lower mechanical effi ciency.165 Exercises with the upper extremity require a higher energy demand than leg exercises at any given submaximal workload, due to the smaller muscle mass, a larger recruitment of type II mus-cle fi bers, a smaller capillary bed, and a higher vascular resistance of the upper extremity.166 Other factors such as fl oor surface,167 propelling speed,168 and wheel-chair design169 also greatly infl uence the energy demand of wheelchair propulsion for people with disabilities. Table 2.10 shows the energy expenditure of manual wheelchair propulsion.
2.5.3 AGINGWITHA DISABILITY
With aging, many body systems and functions deteriorate, such as easily fatigable muscles, reduced cardiac output, reduced ventilatory capacity, reduced muscle mass, reduced fl exibility, decreased bone mineral density, reduced balance ability, and reduced maximal aerobic power.170 Problems in energy expenditure and effi ciency171
TABLE 2.10
Energy Expenditure of Manual Wheelchair Propulsion
References Subjects/Conditions
Oxygen Consumption
(mL/kg/min) Speed (m/min) Wolfe et al.167 Concrete
Normal 11.8 ± 2.6 56.6
Deconditioned 13.0 ± 2.2 53.3
Paraplegic: Hard tires 15.7 ± 5.3 82.7 Paraplegic:
Pneumatic tires
15.7 ± 3.8 79.8
Carpet
Normal subjects 12.5 ± 2.9 43.3
Deconditioned 14.0 ± 1.7 37.5
Paraplegic: Hard tires 16.9 ± 5.0 65.3 Paraplegic:
Pneumatic tires
17.1 ± 4.4 63.6
Mukherjee et al.168 Slow speed 9.52 ± 1.14 24.6
Freely chosen speed 14.02 ± 2.94 56.8
Fast speed 16.36 ± 3.54 72.3
Mukherjee and Samanta169
Arm-crank propelled wheelchair
One arm 10.30 ± 1.14 122.8
Two arms 9.94 ± 0.95 132.5
would only get worse with aging for people with physical disabilities, but there are not many data available in the literature.
Normal aging without any chronic disease is characterized by reduced daily energy expenditure, so elderly people have a higher risk of developing obesity. This is also common in elderly persons with disabilities. Health promotion and wellness programs are needed for this population, with additional factors taken into consid-eration and with suitable modifi cations, such as their medical conditions, overload stress on small muscles of the upper extremity, adaptation of equipment to fi t the specifi c types of disability, accessibility of the training facility, and temperature regulation.170
On the other hand, some elderly have a few chronic diseases that are associ-ated with an increased resting energy expenditure, such as diabetes, congestive heart failure, Parkinson’s disease, Alzheimer’s disease, and COPD.172,173 Poor nutritional intake plus increased resting energy expenditure with chronic diseases were thought to be the possible causes of unexplained weight loss in the elderly.172,173 Therefore, special attention also has to be paid to specifi c exercise conditioning and proper nutritional supplement for the elderly with chronic diseases.
2.5.4 PHYSICAL DISABILITYAND OBESITY
In recent years, health care for people with disabilities has been increasingly focused on the prevention of secondary complications arising from the disabilities. The sec-ondary conditions refer to those preventable medical, emotional, or social problems resulting directly or indirectly from the disability, such as obesity, muscle atrophy, pneumonia, urinary tract infection, depression, fatigue, pressure sore, and joint pain.174 Obesity is not an acute condition, but it has many ramifi cations.
Physical inactivity often results from the functional limitations of the disability, a feeling of depression, and fatigue, leading to an unhealthy lifestyle and adverse behaviors.174 Either due to primary defi cits or disuse, muscle atrophy leads to a decreased fat-free mass and results in a reduction of the resting energy expenditure.
Combining the two factors together, reduced energy expenditure in physical activity and reduced resting energy expenditure lead to reduced total energy expenditure in people with disabilities. Therefore, people with disabilities have a higher tendency to reach a positive energy balance state.
The development of obesity seems to be a vicious cycle for people with disabilities. Obesity compounds the problems of high energy demand of physical activities in people with disabilities, which reduces the likelihood of participation in social activities and exercise, and reduces their ability to care for themselves.
Secondary complications such as hypertension, type II diabetes, and coronary dis-ease develop as obesity continues. It can further lead to many health complications, increasing the health care cost for people with disabilities and the health care burden on society.
One of the federal health focus areas of “Healthy People 2010” encourages people to engage regular moderate-intensity exercise in order to curb the health complica-tions arising from the epidemic of obesity and physical inactivity. Promoting physi-cal activity, aerobic exercise, and muscle strengthening in people with disabilities have become even more important than the health promotion for people without
disabilities. Improved ergonomic design of exercise equipments to fi t people with disabilities would greatly facilitate their participation in leisure physical activities.
Improved physical fi tness in people with disabilities will then be possibly achieved, and prevention of secondary complications will also be accomplished.