Table 1.
Five-day familiarization protocol with running on a treadmill.
Fig 1.
Overload during the training protocols.
Description of the increases in treadmill speed (intensity; panel A) and running time (duration; panel B) during the 40 training sessions in each of the three trained groups. Each circle represents one training session.
Fig 2.
Intensity of the exercise sessions during the three training protocols.
Panel A indicates the percentage of the maximum speed at which the rats were running at three different moments: before, in the middle of (beginning of the fifth week) and at the end of the training protocol. Two-way ANOVA yielded the following results: group effect (F = 133.556, p < 0.001), moment effect (F = 463.267, p < 0.001) and interaction between the two factors (F = 91.745, p < 0.001; n = 21 rats per training group). Panel B indicates the estimated percentage of the peak rate of oxygen consumption at which the rats were running during the last session of the training protocol. One-way ANOVA yielded the following result: group effect (F = 19.798, p < 0.001; n = 8 rats per training group). * Significantly different relative to the beginning of training within an experimental group (p < 0.001). # Significantly different relative to the middle of training within an experimental group (p < 0.001). + Significantly different relative to the DUR group in the same test (p < 0.001). $ Significantly different relative to the ID group in the same test (p < 0.001).
Fig 3.
Body mass was measured at three different time points: incremental exercises (tests) performed prior to the training (or control) protocols and at the end of the 4th and 8th weeks. Two-way ANOVA yielded the following results: group effect (F = 0.754, p = 0.523), moment effect (F = 833.941, p < 0.001) and interaction between the two factors (F = 1.299, p = 0.261). This analysis indicated that, irrespective of the group, body mass was higher in the second than in the first test and higher in the third than in the second and first tests.
Fig 4.
Physical performance of the rats.
Physical performance was measured at three different time points: incremental exercises (tests) performed prior to the training (or control) protocols and at the end of the 4th and 8th weeks. Performance was evaluated by calculating the workload. Two-way ANOVA yielded the following results: group effect (F = 13.583, p < 0.001), moment effect (F = 100.080, p < 0.001) and interaction between the two factors (F = 12.906, p < 0.001). * Significantly different relative to the first test in the same group (p < 0.05). + Significantly different relative to the CON group in the same test (p < 0.05). # Significantly different relative to the second test in the same group (p < 0.05). $ Significantly different relative to the DUR group in the same test (p < 0.05; n = 21 rats per experimental group).
Fig 5.
Peak rate of oxygen consumption (VO2peak) of the rats.
VO2peak, adjusted for the rat’s size (kg-0.75), was measured at two different time points: incremental exercises performed before and after the training (or control) protocols. Two-way ANOVA yielded the following results: group effect (F = 0.696, p = 0.562), moment effect (F = 1.589, p = 0.218) and interaction between the two factors (F = 0.287, p = 0.835; n = 9 rats for the CON group and n = 8 rats for the other groups).
Fig 6.
VO2 (mL.kg-0.75.min-1) of the rats during the incremental exercises.
Incremental exercises were performed at two different time points: before and after the training or control protocols in the CON (panel A), DUR (panel B), INT (panel C) and ID (panel D) groups. Two-way ANOVA yielded the following results: moment effect (A: F = 0.720, p = 0.409; B: F = 3.697, p = 0.075; C: F = 7.343, p = 0.017; D: F = 23.762, p < 0.001), running speed effect (A: F = 85.726, p < 0.001; B: F = 69.683, p < 0.001; C: F = 128.777, p < 0.001; D: F = 104.292, p < 0.001) and interaction between the two factors (A: F = 0.806, p = 0.611; B: F = 0.782, p = 0.678; C: F = 0.378, p = 0.975; D: F = 0.994, p = 0.457). * Significant major effect of moment (p < 0.05). Differences in VO2 caused by running speeds within the experimental groups are not displayed in the figure to avoid an excess description of obvious information; n = 9 rats for the CON group and n = 8 rats for the other groups.
Fig 7.
Gross oxygen cost of running (mL.kg-0.75.m-1) of the rats.
The gross oxygen cost of running was calculated at the last completed stage during incremental exercises performed before and after the training (or control) protocols. Two-way ANOVA yielded the following results: group effect (F = 2.424, p = 0.086), moment effect (F = 7.968, p = 0.009) and interaction between the two factors (F = 5.450, p = 0.004). * Significantly different relative to the measurement obtained prior to the training protocols (p < 0.05). # Significantly different relative to the CON group in the same test (p < 0.01). & Trend toward a significant difference relative to the measurement obtained prior to the control protocol (p = 0.051; n = 9 rats for the CON group and n = 8 rats for the other groups).
Fig 8.
Changes in performance between the first and third tests in the four experimental groups.
Each group was subdivided into rats with lower and higher intrinsic aerobic capacities, as determined by a performance evaluation in the first incremental exercise. Two-way ANOVA of the data presented in panel A (workload) yielded the following results: group effect (F = 11.980, p < 0.001), aerobic capacity effect (F = 35.297, p < 0.001) and interaction between the two factors (F = 2.268, p = 0.092). Two-way ANOVA of the data presented in panel B (VO2peak) yielded the following results: group effect (F = 0.311, p = 0.817), aerobic capacity effect (F = 10.936, p = 0.003) and interaction between the two factors (F = 0.473, p = 0.704; n = 9 rats for the control group and n = 8 rats per training group, with 4 rats with a higher initial VO2peak and 4 rats with a lower initial VO2peak being used in this analysis).