Table 1.
The Mean ± SD of Neuromuscular Junction (NMJ) Morphology Parameters Summarized by Age (n = 24 per group) and Training Conditions (n = 16 per group)
| NMJ Parameter |
Muscle | Younger | Older | Control | 4 wk | 8 wk |
|---|---|---|---|---|---|---|
| Motor endplate area (µm2) | LTA | 263.2 ± 58.8 |
291.7 ± 67.2 |
263.3 ± 67.6 |
277.7 ± 68.2 |
291.3 ± 56.9 |
| MTA | 146.8 ± 37.5 |
185.1 ± 56.01a |
154.7 ± 54.4 |
173.4 ± 56.3 |
169.8 ± 42.7 |
|
| Motor endplate dispersion (%) | LTA | 22.0 ± 9.0 |
25.0 ± 12.0 |
31.9 ± 10.9 |
20.3 ± 6.5b |
18.3 ± 8.7b |
| MTA | 15.8 ± 8.7 |
18.5 ± 9.1 |
19.1 ± 8.7 |
17.0 ± 9.6 |
15.2 ± 8.6 |
|
| Overlap (%) | LTA | 71.2 ± 25.2 |
80.1 ± 20.8 |
74.6 ± 21.2 |
75.6 ± 22.2 |
76.8 ± 27.4 |
| MTA | 94.0 ± 8.6 |
95.0 ± 5.8 |
93.7 ± 9.9 |
93.6 ± 6.5 |
96.0 ± 4.6 |
Notes: LTA = lateral thyroarytenoid; MTA = medial thyroarytenoid. Although there were no significant differences between age groups in the laryngeal muscle, average motor endplate dispersion ratios were larger in the older control group compared to the younger control group, which is consistent with morphological patterns in NMJs with senescence. These descriptive differences align with previous literature by Johnson et al. (13) showing greater dispersion ratios in older control animals compared to younger animals.
aSignificant age difference (p ≤ .05) from young group.
bSignificant training difference (p ≤ .05) from control group.