Purpose: To quantify the relationship between total training load and running performance during the most important competitions of the season (national cross-country championships, 4.175- and 10.130-km races).
Methods: Eight well-trained, subelite endurance runners (age (mean ± SD): 23 ± 2 yr; V̇O2max: 70.0 ± 7.3 mL·kg-1·min-1) performed a maximal cardiorespiratory exercise test before the training period to determine ventilatory threshold (VT) and respiratory compensation threshold (RCT). Heart rate was continuously recorded using telemetry during each training session over a 6-month macrocycle, designed to achieve peak performance during the aforementioned cross-country races, lasting from late August to the time that these races were held, that is, mid-February. This allowed us to quantify the total cumulative time spent in three intensity zones calculated as zone 1 (low intensity, lower than the VT); zone 2 (moderate intensity, between VT and RCT); and zone 3 (high intensity, above the RCT).
Results: Total training time in zone 1 (4581 ± 979 min) was significantly higher (P < 0.001) than that accumulated in zones 2 (1354 ± 583 min) and 3 (487 ± 154 min). Total time in zone 2 was significantly higher than time in zone 3 (P < 0.05). A correlation coefficient of r = -0.79 (P = 0.06) and r = -0.97 (P = 0.008) was found between the total training time spent in zone 1 and performance time during the short and long cross-country races, respectively.
Conclusions: Our findings suggest that total training time spent at low intensities might be associated with improved performance during highly intense endurance events, especially if the event duration is ∼35 min. Interventional studies (i.e., improving or reducing training time in zone 1) are needed to corroborate our findings and to elucidate the physiological mechanisms behind them.