# Effects of Obesity on Adaptation Transfer from Treadmill to Over-Ground Walking
## 3 Results  
Figure 2 shows changes in double-limb support time symmetry (Figure 2a) and step length symmetry (Figure 2c) over the course of over-ground and split-belt treadmill walking. There was no statistically significant interaction between the groups and the adaptation conditions on double-limb support time symmetry (\(F(1,72)=0.01\), \(p=0.94\), \(\eta p^{2}<0.01\); Figure 2b) and step length symmetry (\(F(1,72)=0.17\), \(p=0.68\), \(\eta p^{2}<0.01\); Figure 2d). The main effect of the groups showed no significant difference in double-limb support time symmetry (\(F(1,72)=0.66\), \(p=0.42\), \(\eta\,p^{2}<0.01\)) and step length symmetry (\(F(1,72)=0.30\), \(p=0.59\), \(\eta\,p^{2}<0.01\)). The main effect of the adaptation condition showed that there were significant differences in double-limb support time symmetry (\(F(1,72)=197.59\), \(p<0.01\), \(\eta\,p^{2}=0.70\)) and step length symmetry (\(F(1,72)=961.74\), \(p<0.01\), \(\eta\,p^{2}=0.92\)) between the tied-belt treadmill baseline (BLT) and early split-belt treadmill adaptation (EAT), indicating that both groups were perturbed when the belts were first split (i.e., walking asymmetrically with inter-limb difference).  
There was a statistically significant interaction between the groups and washout conditions on double-limb support time symmetry (\(F(1,72)=5.68\), \(p=0.02\), \(\eta\,p^{2}=0.10\); Figure 2b). The symmetry value for the double-limb support time was significantly greater in adults with obesity than in adults with normal weight during the early tied-belt washout period (when the split-belt perturbation is removed). The symmetry value for the double-limb support time was similar between adults with obesity and adults with normal weight during tied-belt baseline. There was no significant interaction between the groups and washout conditions regarding step length symmetry (\(F(1,72)=2.91\), \(p=0.09\), \(\eta\,p^{2}=0.03\); Figure 2d). The main effect of the group showed no significant difference in step length symmetry between adults with obesity and adults with normal weight (\(F(1,72)=2.39\), \(p=0.13\), \(\eta\,p^{2}=0.02\)). The main effect of the washout condition showed that there was a significant difference in step length symmetry between the tied-belt treadmill baseline (BLT) and the early tied-belt treadmill washout (EWT) (\(F(1,72)=241.95\), \(p<0.01\), \(\eta\,p^{2}=0.74\)), indicating that both groups showed aftereffects (i.e., walking asymmetrically with inter-limb difference in the opposite direction).  
and step length symmetry (\(F(1,72)=250.91,p<0.01,\eta p^{2}=0.75\)) between the early split-belt treadmill adaptation (EA\({}_{\text{T}}\)) and the early split-belt treadmill re-adaptation (ERA\({}_{\text{T}}\)), indicating that both groups experienced smaller errors early in the re-adaptation period rather than early in the initial adaptation period (i.e., participants were less perturbed by the split-belts).  
Figure 3 shows that there was a significant difference in the transfer of double-limb support time symmetry (from the treadmill to over-ground walking) between groups. The transfer index for double-limb support time symmetry was less in adults with obesity than in adults with normal weight (\(t(36)=3.49,p<0.01,d=0.75\); Figure 3b). However, the transfer index for step length symmetry was not statistically different in adults with obesity compared to adults with normal weight (\(t(36)=0.58,p=0.15,d=0.17\); Figure 3a).