Biomedical Engineering Reference
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obese after 12 weeks (1.25 ± 0.09 m/s) and 64 weeks (1.25 ± 0.09 m/s) com-
pared to baseline (1.19 ± 0.09 m/s).
Plewa et al. [ 44 ] examined the effects of 3 months of diet-exercise-induced
weight loss on several kinematic gait parameters in obese women. They reported
several significant differences between baseline and follow-up measurements.
Walking speed was significantly faster (1.07 ± 0.2 m/s vs. 1.12 ± 0.22 m/s), the
stride length significantly longer (1.21 ± 0.14 m vs. 1.24 ± 0.15 m), the swing
time significantly greater (33.99 ± 1.93 % vs. 34.48 ± 2 %), the cycle time
significantly shorter (1.15 ± 0.12 s vs. 1.13 ± 0.13 s) and the step frequency
significantly higher (105.25 ± 10.47 steps/min vs. 107.78 ± 11.72 steps/min)
after an average weight reduction of 7.4 % [ 44 ]. Moreover, the stance time
(65.88 % ± 1.92 % vs. 65.37 % ± 2.04 %) and double support time
(15.99 % ± 1.95 % vs. 15.52 % ± 2.02 %) were significantly lower after weight
loss [ 44 ].
5.1.1 Knee Osteoarthritis
Although weight loss has been shown to be an evidence-based symptomatic
treatment for knee OA [ 2 , 18 ], and to reduce the risk of symptomatic knee OA
[ 14 ], the effects of weight loss on joint loadings in obese knee OA patients have
only been examined in two studies [ 1 , 34 ]. The adduction moment in the frontal
plane is highlighted, because patients with knee OA are claimed to exhibit a
significantly higher knee adduction moment, and an increase in this moment is
associated with the progression of knee OA [ 15 ].
Messier et al. [ 34 , 36 ] investigated the effects of 18 months of diet and exercise
in a randomized clinical trial (Arthritis, Diet, and Activity Promotion Trial
(ADAPT)) during walking at the self-selected speed. The ADAPT study was
designed to compare the effects of four distinct interventions: (1) exercise, (2)
dietary weight loss (diet), (3) dietary weight loss and exercise (diet-exercise), and
(4) a healthy lifestyle (control) in older overweight and obese adults with knee OA.
Both weight loss intervention groups lost significantly more weight (diet (an
average of 4.9 %) and diet-exercise (an average of 5.7 %)) compared to the
healthy lifestyle group [ 36 ]. The average weight loss in their study was only
2.6 %. Messier et al. [ 34 ] showed that a one-kilogram reduction in body weight
was associated with a 1.4 % reduction in the peak knee abduction moment after
statistically adjusting for several variables including age, walking speed, gender,
and subjective scores for knee pain and function. In a secondary data analysis,
Messier et al. [ 35 ] investigated the effects of high weight loss in participants who
lost over 5 % weight compared to those who lost less than 5 %, or who did not
lose or gained weight. The walking speed increased significantly in the high
(change 6.8 %) and low (change 7.4 %) weight loss groups, but not in the no
weight loss group [ 35 ]. The knee abduction and extension moments did not differ
between the groups after weight loss [ 35 ], but adjusted data revealed lower
maximum knee compressive forces with a greater weight loss. The difference in
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