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We present \textit{Spitzer Space Telescope} variability monitoringobservations of three low-gravity L dwarfs with previous detections ofvariability in the near-IR, 2MASS J0045+16, 2MASS J0501-00 and 2MASS J1425-36.We detect significant, periodic variability in two of our targets, 2MASSJ0045+16 and 2MASS J0501-00. We do not detect variability in 2MASS J1425-36.Combining our new rotation periods with rotational velocities, we calculateinclination angles of $22\pm1^{\circ}$, ${60^{+13 }_{-8}} ^{\circ}$ and$52^{+19}_{-13}~^{\circ}$ for 2MASS J0045+16, 2MASS J0501-00 and 2MASS J1425-36respectively. Our three new objects are consistent with the tentative relationsbetween inclination, amplitude and color anomaly previously reported. Objectswith the highest variability amplitudes are inclined equator-on, while themaximum observed amplitude decreases as the inclination angle decreases. Wealso find a correlation between the inclination angle and$(J-K)_{\mathrm{2MASS}}$ color anomaly for the sample of objects with measuredinclinations. Compiling the entire sample of brown dwarfs with \textit{Spitzer}variability detections, we find no enhancement in amplitude for young, early-Ldwarfs compared to the field dwarf population. We find a possible enhancementin amplitude of low-gravity late-L dwarfs at $4.5~\mu$m. We do not find acorrelation between amplitude ratio and spectral type for field dwarfs or forthe young population. Finally, we compile the rotation periods of a largesample of brown dwarfs with ages 1 Myr to 1 Gyr and compare the rotation ratespredicted by evolutionary models assuming angular momentum conservation. Wefind that the rotation rates of the current sample of brown dwarfs fall withinthe expected range set by evolutionary models and breakup limits.

Spitzer Variability Properties of Low-Gravity L Dwarfs