SPEXOR passive spinal exoskeleton decreases metabolic cost during symmetric repetitive lifting

Abstract

Purpose Besides mechanical loading of the back, physiological strain is an important risk factor for low-back pain. Recently a passive exoskeleton (SPEXOR) has been developed to reduce loading on the low back. We aimed to assess the effect of this device on metabolic cost of repetitive lifting. To explain potential effects, we assessed kinematics, mechanical joint work, and back muscle activity. Methods We recruited ten male employees, working in the luggage handling department of an airline company and having ample experience with lifting tasks at work. Metabolic cost, kinematics, mechanical joint work and muscle activity were measured during a 5-min repetitive lifting task. Participants had to lift and lower a box of 10 kg from ankle height with and without the exoskeleton. Results Metabolic cost was significantly reduced by 18% when wearing the exoskeleton. Kinematics did not change significantly, while muscle activity decreased by up to 16%. The exoskeleton took over 18-25% of joint work at the hip and L5S1 joints. However, due to large variation in individual responses, we did not find a significant reduction of joint work around the individual joints. Conclusion Wearing the SPEXOR exoskeleton decreased metabolic cost and might, therefore, reduce fatigue development and contribute to prevention of low-back pain during repetitive lifting tasks. Reduced metabolic cost can be explained by the exoskeleton substituting part of muscle work at the hip and L5S1 joints and consequently decreasing required back muscle activity.

The Effects of Upper-Body Exoskeletons on Human Metabolic Cost and Thermal Response during Work Tasks—A Systematic Review

“…Table 1 shows an overview of the main characteristics of the nine considered studies [ 26 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ], following the PICO model and highlighting the type of exoskeleton used. All the articles that met the eligibility criteria are very recent—eight were published between 2019 and 2020 and one, the oldest, in 2014.…”

“…A total of 99 subjects were recruited in the included studies, but 94 performed the metabolic test, with a predominance of males (76 males (M), 15 females (F), and 3 subjects whose gender was not specified). The subjects’ mean age varied from less than 25 (six out of nine studies) up to 47 [ 42 ].…”

“…All the studies were carried out in the laboratory. Most of them (six out of nine, [ 38 , 40 , 41 , 42 , 44 , 45 ]), chose a repetitive lifting task to be performed in the experimental trial, two out of nine [ 26 , 39 ] selected an overhead working task and one considered a static holding posture of the trunk [ 43 ]. All the studies were based on the comparison between the “with exoskeleton condition (WEC)” and “without exoskeleton condition (WOEC)”.…”

“…In total, eight different UBEs were investigated: seven BSEs [ 38 , 40 , 41 , 42 , 43 , 44 , 45 ] and one ULSE [ 26 , 39 ]. Among them, seven were passive assistive devices and one [ 45 ] was an active device.…”

“…Seven studies [ 26 , 40 , 41 , 42 , 43 , 44 , 45 ] had a moderate risk of bias due to confounding, since they recruited only male subjects. Considering that the subjects performing trials in WEC and in WOEC were the same and given the nature of the experimental setup, the authors assigned to all studies a low risk of bias due to the selection of participants, classification of the interventions, deviation from the intended interventions, missing data and measurements of outcomes.…”