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Hip joint impairment due to fracture or arthritis is common in older people. Handicaps such as these cause a decrease in walking efficiency, so that more energy is needed to walk. Older people who have hip problems commonly also have cardiorespiratory problems and age-related decreases in maximal heart rate and oxygen consumption (indicators of energy availability), and it is possible that the increase in energy needed to walk may approach these physiological limits. Energy expenditure during walking was evaluated in 12 people with hip joint impairment and 10 healthy controls; the factors which contribute to different energy costs were examined. Pain limited the top speeds at which individuals with hip impairment could walk. Their oxygen consumption (VO2) was greater than control levels 52 percent of the time when tested on a level-surface treadmill, but was greater than control only 37 percent of the time when testing on a five-degree incline. The number of steps per minute (stepping frequency) in the patient group was greater than control 80 percent of the time. Thus, the VO2 per step was less in hip-impaired patients, and the increased stepping frequency is probably a compensatory mechanism. These changes in walking patterns were not related to range of motion (flexibility) or to degree of change in hip joint anatomy, but were related to pain experienced during walking. The increased energy cost of walking is discussed in terms of the imbalances caused by hip dysfunction and hip pain. Evaluation of patients with hip impairment by including analysis of energy cost is recommended as a way to assess efficacy of therapy. (Consumer Summary produced by Reliance Medical Information, Inc.), The energy cost of walking was measured in 12 patients (age 39-73 years) with hip joint impairment and 10 healthy controls during unassisted walking 2-6 km*h[.sup.-1) on a level treadmill surface and on a 5% incline. The energy cost of locomotion in most patients increased up to 50% and 70% during level-surface and uphill walking, respectively This difference between patients and controls was probably due to the increased external mechanical work. The energy cost of walking although related to pain experienced during walking but not to hip joint range of motion or to joint status evaluated radiographically, provides an additional variable when defining the conditions of disability and functional impairment in individuals with this pathological condition. [Gussoni M, Margonato V, Ventura R, et ah Energy cost of walking with hip joint impairment. Phys Ther 70:-295-301,1990], Key Words:Energy expenditure; Hip joint; joint instability; Kinesiology/biomechanics, general; Locomotion. The energy cost of uphill, downhill, and level-surface treadmill walking in healthy subjects has been carefully investigated during the past [...]

Objective: While in adulthood there is no proven relationship between back pain and trunk muscle strength, in pre-pubertal subjects this topic has been poorly studied. The aim of the study was to evaluate isometric and isokinetic trunk muscle strength in children with or without previous back pain. Methods: The recent occurrence of back pain (last 6 months) among 144 children (77 males, 67 females, age 11.9 ± 0.3 years) was assessed using a questionnaire. Extensor and flexor trunk muscle strength was measured through isometric and isokinetic (60, 90, 120°/s) tests. Peak torque (PT), PT angle, PT flexor/PT extensor ratio and intra-session coefficient of variation (COV) were determined. Results: Flexor and extensor muscle PT, but not PT angle, were significantly higher in males than in females, irrespective of back pain occurrence. PT flexor/PT extensor ratio at 90° angular velocities increased significantly only in males with back pain, compared with males without back pain. The COV trend was similar for flexor and extensor muscles. Conclusions: Isometric and isokinetic trunk muscle strength probably play a minor role in back pain occurrence in children. The isokinetic testing velocity may be important in determining trunk strength differences between children with and without back pain.