Validation of the Stanford Leisure-Time Activity Categorical Item (L-Cat) using armband activity monitor data.

Objective: Accurate assessment of physical activity (PA) in public health and healthcare settings remains a challenge given limitations of existing brief assessment tools. The Stanford Leisure-Time Activity Categorical Item (L-Cat), a single item with six categories, has previously demonstrated excellent reliability and adequate validity relative to pedometer steps. However, pedometers cannot assess key dimensions of PA intensity or duration.

Methods: We evaluated the L-Cat's criterion validity and sensitivity to change relative to objectively measured Sensewear armband activity monitors among 76 adults with overweight/obesity (mean age 50.8 ± 11.9 years, BMI = 33.1 ± 3.4 kg m-2 ) at baseline and end of a 6-month behavioural weight management pilot trial.

Results: At baseline, L-Cat category was associated with armband-measured daily steps (Spearman's ρ = 0.41, p < 0.001), total weekly minutes of moderate/vigorous-intensity PA (MVPA) (ρ = 0.40, p < 0.001) and weekly minutes of MVPA accumulated in bouts ≥10 min (ρ = 0.47, p < 0.0001). Participants increasing ≥1 L-Cat category from baseline to 6 months had greater increases in steps (1,110.1 ± 1,852.1 vs. -18.0 ± 2,005.6 steps/d, p = 0.032), total minutes of MVPA (145.7 ± 180.6 vs. -2.1 ± 215.8 min/week, p = 0.007) and greater weight losses (-7.4 ± 7.7% vs. -3.1 ± 4.8%, p = 0.013) than those who stayed the same/decreased L-Cat categories.

Conclusion: The L-Cat demonstrated adequate criterion validity and excellent sensitivity to change relative to objectively measured PA among behavioural weight management pilot trial participants. The L-Cat may be particularly useful for identifying individuals at lower activity levels and when using all six categories.