Influence of Interval Training Frequency on Time-Trial Performance in Elite Endurance Athletes

Figure 1. Weekly training load in the 12-week intervention period. The figure shows the distribution of endurance training in the different intensity zones (I-1 to I-5) and duration of strength training in the high- and low-frequency group (HF- and LF group). Values are presented as the median and IQR. There were no statistically significant differences between the groups.

Figure 2. Time taken to complete the 8 km rollerski time-trial, pre-test and post-test, in the low-frequency group (LF group) and high-frequency group (HF group). Reference lines indicate identical values pre- and post-test. Each box represents a test subject. Open boxes indicate an improvement, and filled boxes indicate a decline, compared to the pre-test.

Figure 3. VO2max at pre-test and post-test, in the low-frequency group (LF group) and high-frequency group (HF group). Reference lines indicate identical values pre- and post-test. Each box represents a test subject. Open boxes indicate an improvement and filled boxes indicate a decline, compared to the pre-test.

Figure 4. % of VO2max at anaerobic threshold at pre-test and post-test, in the low-frequency group (LF group) and high-frequency group (HF group). Reference lines indicate identical values at pre- and post-test. Each box represents a test subject. Open boxes indicate an improvement and filled boxes indicate a decline, compared to the pre-test.

Figure 5. VO2 at 5% incline and a speed of 10.8 km/h at pre-test and post-test, in the low-frequency group (LF group) and high-frequency group (HF group). Reference lines indicate identical values at pre- and post-test. Each box represents a test subject. Open boxes indicate an improvement and filled boxes indicate a decline, compared to the pre-test. * = 9.0 km/h for women.

Figure 6. Heart rate at a speed of 10.8 km/h at pre- and post-test, in the low-frequency group (LF group) and high-frequency group (HF group). Reference lines indicate identical values at pre- and post-test. Each box represents a test subject. Open boxes indicate an improvement and filled boxes indicate a decline, compared to the pre-test. * = 9.0 km/h for women.