TABLE 4:

Analysis of swimming locomotion.

Parameter	wt	Pax7-Cre/cKO
FL strokesa	13.5 ± 0.5	33.7 ± 0.7**
Tail's sinusoidal oscillationsb	18.1 ± 1.3	2.3 ± 0.1***
“Out-of phase” cycles in HLsc	0.4 ± 0.1	1.8 ± 0.6
Velocity (cm/s)	36.3 ± 2.5	23.4 ± 1.0***

Mice were video recorded while swimming (see Supplemental Figure S6D and Supplemental Videos S9 and S10). Measurements were made for each stroke and values averaged. Note that in contrast to wt mice, for which the navigation and main driving force during swimming were well-coordinated HL strokes, continuous sinusoidal tail oscillations, and only sporadic FL strokes (see also Supplemental Video S9), Pax7-Cre/cKO mice completely lacked tail oscillations and extensively used their FLs; the latter most probably was a compensatory mechanism for impaired HL function (see also Supplemental Video S10). In addition, in mutant mice, slightly impaired left–right HL coordination during swimming was observed (see also Supplemental Video S10). As a consequence, swimming velocity of Pax7-Cre/cKO mice was reduced ∼1.5-fold compared with wt mice. Mice examined: wt, 27; Pax7-Cre/cKO, 20. Mean ± SEM.

^aNumber of FL strokes per distance swum.

^bNumber of tail oscillations upon HL extension.

^cAn “out-of-phase” cycle is when strokes of an identical limb occur in a row. Number of “out-of-phase” cycles per run is shown.

*p < 0.05, **p < 0.01, ***p < 0.001, unpaired Student's t test.