Levels ofβ-endorphin immunoreactivity
| Naloxone | Normal saline | p-value (95% CI) | |
| Baseline | 6.3±2.0 | 6.0±1.8 | 0.45 (-0.46–0.99) |
| End-exercise | 19.8±4.7 | 19.3±5.5 | 0.72 (-2.57–3.64) |
| 30 min post-exercise | 8.7±2.6 | 7.8±1.7 | 0.15 (-0.37–2.22) |
Data are given in pg·mL−1 and presented as mean±sd, unless otherwise stated. CI: confidence interval.