Table 2.
Effects of 5 km time trial exercise on quadriceps muscle functions
| Percentage change from pre- to 3 min postexercise |
|||
|---|---|---|---|
| Control | Placebo | Intrathecal fentanyl | |
| Qtw,pot (N) | −32.4 ± 1.9 | −33.1 ± 1.9 | −45.6 ± 1.9* |
| MRFD (N s−1) | −28.2 ± 1.6 | −29.3 ± 2.9 | −43.8 ± 2.7* |
| MRR (N s−1) | −30.1 ± 1.3 | −30.7 ± 2.4 | −43.4 ± 2.9* |
| CT (s) | −6.8 ± 0.6 | −6.9 ± 0.6 | −6.9 ± 0.6 |
| RT0.5 (s) | 7.3 ± 0.3 | 7.2 ± 0.3 | 9.4 ± 0.6* |
| MVC peak force (N) | −7.9 ± 0.6 | −8.5 ± 0.8 | −14.5 ± 2.0* |
| Percentage voluntary muscle activation | 0.0 ± 0.64† | −0.8 ± 0.52† | −1.6 ± 0.7 |
Peripheral fatigue was assessed via supramaximal magnetic stimulation of the femoral nerve before and 3 min after exercise. Changes in fatigue variables are expressed as a percentage change from pre-exercise baseline to 3 min after the completion of exercise. Values are expressed as means ±s.e.m. Abbreviations: Qtw,pot, potentiated single twitch; MRFD, maximal rate of force development; MRR, maximal rate of relaxation; CT, contraction time; RT0.5, one-half relaxation time; and MVC, maximal voluntary contraction. Percentage muscle activation is based on superimposed twitch technique. Most of the variables changed significantly compared with baseline 3 min after exercise (P < 0.01).
P < 0.01 versus control and placebo.
Not significantly different from pre-exercise baseline. Pre-exercise, resting mean values for potentiated single twitch, MRFD, MRR, CT and RT0.5 were 171 ± 3 N, 1499 ± 17 N s−1, 1011 ± 10 N s−1, 0.26 ± 0.00 s and 0.12 ± 0.00 s, respectively; n= 8 subjects.