LPL studies indicate that the underlying cellular events during inactivity (NEAT deficiency) are distinct from the cellular events after exercise training
| Inactivity mechanisms | Exercise mechanisms | |
|---|---|---|
| Comparison studied for LPL | Inactivity (not standing) vs. normal spontaneous intermittent standing/ambulation during nonexercise physical activity | Exercise vs. normal nonexercise physical activity (spontaneous intermittent standing/ambulation) |
| Fiber type mostly affected | Red oxidative muscle fibers have ≥10-fold lower LPL activity during inactivity | White glycolytic muscle fibers have 2.5-fold greater LPL activity after exercise |
| LPL mRNA involvement | No difference in LPL mRNA between inactive and control | LPL mRNA expression increases 2.5-fold in multiple glycolytic muscles after exercise |
| Evidence of inhibitory pathway | Transcription of an inhibitory gene suppresses LPL by a posttranslational mechanism | No evidence for inhibitory gene |
The mechanisms regulating LPL during physical inactivity (“Inactivity mechanisms” column) and during exercise training (“Exercise mechanisms” column) were studied in comparison with the same referent control group (i.e., normal Sprague-Dawley rats with only intermittent and spontaneous nonexercise physical activity). Table is redrawn from refs. 1,2,85.