A 14-Day Recovery and Physical Activity Levels After an Ankle Sprain in Mice.

CONTEXT: Research is needed to find ways of improving physical activity after a lateral ankle sprain.

OBJECTIVE

To investigate the effects of a prolonged rest period on lifelong activity after a surgically induced ankle sprain.

DESIGN

Controlled laboratory study.

SETTING

Research laboratory.

PATIENTS OR OTHER

PARTICIPANTS

A total of 18 male CBA/J mice (age at surgery = 7 weeks).

MAIN OUTCOME MEASURE(S): We transected the anterior talofibular ligament and calcaneofibular ligament of the right hindlimb. Each mouse was placed in a separate cage and randomized into 1 of 3 groups of 6 mice each. A running wheel was placed in each cage at 3 days, 7 days, or 14 days after surgery. Physical activity was measured daily. Daily duration (ie, time spent on the wheel), distance, and running speed were examined using analysis of variance (group × age) with repeated measures at 15-week periods to approximate the first 3 quartiles of the lifespan.

RESULTS

From weeks 3 to 15 after surgery, we observed no differences in duration, distance, or running speed among groups (P > .05). From weeks 16 to 30, distance (F2,14 = 0.57, P = .041) and running speed (F2,14 = 0.93, P = .01) were greater in the 14-day group than in the 3- and 7-day groups. From weeks 31 to 45, duration (F2,14 = 0.74, P = .02), distance (F2,14 = 0.95, P = .009), and running speed (F2,14 = 1.05, P = .007) were greater in the 14-day group than in the 3- and 7-day groups.

CONCLUSIONS

Our findings suggest that the longer recovery period of 14 days can increase activity levels throughout the lifespan after a severe ankle sprain. Rest after an ankle injury is critical to restoring physical activity levels across the lifespan. Rest and time away from exercise after an ankle sprain may be necessary to restore physical activity to normal, uninjured levels.