Gait energetic efficiency in older adults with and without knee pain: results from the Baltimore Longitudinal Study of Aging.

With aging, customary gait patterns change and energetic efficiency declines, but the relationship between these alterations is not well understood. If gait characteristics that develop with aging explain part of the decline in energetic efficiency that occur in most aging individuals, then efforts to modify these characteristics could delay or prevent mobility limitation. This study characterizes gait patterns in older persons with and without knee pain and tests the hypothesis that changes in gait characteristics due to knee pain are associated with increased energetic cost of walking in older adults. Study participants were 364 men and 170 women aged 60 to 96 years enrolled in the Baltimore Longitudinal Study of Aging (BLSA), of whom 86 had prevalent knee pain. Gait patterns were assessed at participant self-selected usual pace in the gait laboratory, and the energetic cost of walking was assessed by indirect calorimetry during self-selected usual pace walking over 2.5 min in a tiled corridor using a portable equipment. Participants with knee pain were less energetically efficient than those without pain (oxygen consumption 0.97 vs. 0.88 ml/(10 m · 100 kg); p = 0.002) and had slower gait speed and smaller range of motion (ROM) at the hip and knee joints (p < 0.05, for all). Slower gait speed and lower knee ROM in participants with knee pain and longer double support time and higher ankle ROM in participants without knee pain were associated with lower energetic efficiency (p < 0.05, for all). Slower gait speed and lower knee ROM were correlates of knee pain and were found to mediate the association between age and oxygen consumption. Although knee pain is associated with a higher energetic cost of walking, gait characteristics associated with energetic efficiency differ by pain status which suggests that compensatory strategies both in the presence and absence of pain may impact gait efficiency.