This study evaluated the ability of two different methods of measuring mechanical work, absolute power (AP) and absolute work (AW), to distinguish between normal and impaired gait. The relation between these two measures was examined as well as their relation to oxygen consumption. Global work measures from all three were compared and, in the case of the absolute power method individual joint power curves of the ankle, knee and hip, for normal and two impaired conditions were examined. Four subjects of each gender were filmed for one full gait cycle, by three video cameras, over two AMTI force platforms, under three conditions;​ normal, locked knee and locked ankle. Oxygen consumption was measured with a TEEM 100 unit carried by the subject in a “fanny” pack. Five normal gait trials and one trial of each impaired condition were analysed. The five normal gait trials yielded a normal mean plus or minus a 95% confidence interval. IT any of the two condition’s trials fell outside of this interval it was considered significantly different. A binomial test considered the probability that the number of differences across subjects was due to chance. For the absolute power method the ankle was different three of eight times (P=0.0058), and the knee two of eight (P=0.057). The absolute work method found differences one of eight times for each condition, neither was significant. A repeated measures ANOVA revealed no differences due to the extremely high intersubject variability. A Wilcoxon, matched pairs, signed ranks test found that the number of locked knee trials where the total work done as measured by the AP method were lower than the subjects’ normal trials to be significant. Thus, locked knee walking required less energy than the normal gait trials.

Efficiency was measured for both, methods using both internal and external work. The total work yielded the same pattern for both methods. Locked knee walking was lowest (AP:​ 92.9%, AW:​ 57.03%) while the locked ankle walking was highest (AP:​ 115.4%, AW:​ 66.7%). The normal gait trials yielded a mean efficiency of 106.7% for AP and 59.26% for AW. Results over 100% for AP are due to an inherent overestimation of the internal work;​ corrections for this would reduce the value to approximately 70%.

The grand mean of the normal trials was closely examined and found to match very closely with previous data (Winter 1983) with, respect to the ankle and knee joint power patterns. New patterns at the hip are put forth as being consistent and confirmative to expected muscle recruitment during normal gait. The power bursts were present in the normal grand mean curve of the hip:​ H1, a concentric extensor moment pushed the centre of mass forward, H2, an eccentric flexor moment absorbed a dip in the centre of mass and H3, a concentric flexor moment swung the leg forward. The research showed that the absolute work method could not detect impaired gait from normal while the absolute power method could.