Effects of obesity class on flat ground walking and obstacle negotiation.

OBJECTIVES: Although much is known about the impact of obesity on gait, not much is understood about how classes of obesity affect movement. The purpose of this study was to examine the effects of weight classification on walking. METHODS: Sixty-seven women with normal BMI (n=13), overweight/Class I obesity (n=18), Class II obesity (n=16), and Class III obesity (n=20) participated. Gait parameters (velocity and percent of the gait cycle spent in swing and stance phases) were collected as participants walked on flat ground and crossed three obstacle heights. RESULTS: Adults with normal BMI had faster velocities (F(3,63)=12.60, p=.000017), shorter portions of the gait cycle spent in stance (F(3,62)=7.29, p=.00029), and a larger percent of the gait cycle spent in swing than those with higher BMI scores (F(3,62)=5.43, p=.002). Adults with overweight/Class I obesity had faster velocities than those with Class III obesity (p=.000082, d=1.20) as well as less variable velocities than those with Class II (p=.002, d=-.40) and Class III (p=.01, d=-1.0) obesity. No differences in velocity were found between those with Class II and Class III obesity (p=.12, d=.57). CONCLUSIONS: These results suggest the need to encourage adults to decrease overweight/Class I obesity but that an equally important goal is to prevent an increase in BMI leading to Class II obesity.