Do mechanical gait parameters explain the higher metabolic cost of walking in obese adolescents?

Abstract

Net metabolic cost of walking normalized by body mass (C(W.BM(-1)); in J.kg(-1).m(-1)) is greater in obese than in normal-weight individuals, and biomechanical differences could be responsible for this greater net metabolic cost. We hypothesized that, in obese individuals, greater mediolateral body center of mass (COM) displacement and lower recovery of mechanical energy could induce an increase in the external mechanical work required to lift and accelerate the COM and thus in net C(W.BM(-1)). Body composition and standing metabolic rate were measured in 23 obese and 10 normal-weight adolescents. Metabolic and mechanical energy costs were assessed while walking along an outdoor track at four speeds (0.75-1.50 m/s). Three-dimensional COM accelerations were measured by means of a tri-axial accelerometer and gyroscope and integrated twice to obtain COM velocities, displacements, and fluctuations in potential and kinetic energies. Last, external mechanical work (J.kg(-1).m(-1)), mediolateral COM displacement, and the mechanical energy recovery of the inverted pendulum were calculated. Net C(W.BM(-1)) was 25% higher in obese than in normal-weight subjects on average across speeds, and net C(W.BM(-67)) (J.kg(-0.67).m(-1)) was significantly related to percent body fat (r(2) = 0.46). However, recovery of mechanical energy and the external work performed (J.kg(-1).m(-1)) were similar in the two groups. The mediolateral displacement was greater in obese subjects and significantly related to percent body fat (r(2) = 0.64). The mediolateral COM displacement, likely due to greater step width, was significantly related to net C(W.BM(-67)) (r(2) = 0.49). In conclusion, we speculate that the greater net C(W.BM(-67)) in obese subjects may be partially explained by the greater step-to-step transition costs associated with wide gait during walking.

Effects of obesity on functional capacity

“…Few studies (13,(24)(25)(26) evaluated the effect of weight loss programs on functional capacities and movement characteristics, and few demonstrated that weight loss increased gait speed, stride length, swing time, hip range of motion, maximal knee flexion, ankle plantar flexion, 1-leg limb stance time, and self-reported physical function, whilst also reducing frailty.…”

Energetics and mechanics of walking in patients with chronic low back pain and healthy matched controls

“…Two inertial sensors equipped with a triaxial accelerometer and gyroscope (MTx, Xsens, Enschede, The Netherlands) were used to calculate the three-dimensional accelerations of walking as previously described by Peyrot et al (2009). An inertial/gyroscope sensor was taped and secured directly to the skin on the lower part of the back, at the L3 level (close to the centre of body mass, COM) using an adhesive strap.…”

“…Data were processed according to the methodology previously described by Peyrot et al (2009) Briefly, the inertial sensors provided orientation data in the earth reference system in the form of Euler angles (roll, pitch and heading), which represent rotations of the sensor system into the earth reference system. Since the magnetic north corresponded to the anteroposterior axis in the present study, the three-dimensional accelerations of the two sensors were repositioned in the earth reference system using rotation matrices.…”

Humans exploit the biomechanics of bipedal gait during visually guided walking over complex terrain

“…We also calculated energy recovery, which is a measure of the efficiency of the transduction between potential and kinetic energy during walking [31,[37][38][39][40][41][42]. Percentage energy recovery (%ER) refers to the amount of work done to increase the potential energy of the COM that is recovered in the form of kinetic energy, such that…”

“…As such, %ER provides an additional test of the efficiency with which subjects are able to capitalize on the dynamics of their biomechanical structure. Under ideal conditions, humans have been found to achieve %ER values between 65 and 70 per cent [38][39][40], so if the visibility manipulation does affect subjects' ability to efficiently exploit their biomechanical structure, we should expect to see a resultant drop in %ER.…”