Changes in laboratory and field-based measurements in highly trained endurance runners across a training year.

We examined the effects of one year's endurance training on laboratory and field-based fitness measures in highly trained distance runners. Fourteen distance runners (mean±SD: age 28±8 y, body mass 67.0±6.3 kg, VO2max 69.8±6.3 mL.kg(-1).min(-1)) with at least 2 years competitive experience completed 5 laboratory and 9 field tests across a 12 month period, during which time training volume and intensity were monitored. The laboratory tests measured VO2max, lactate threshold (LT) and running economy, whilst the field tests measured critical speed (CS) and the maximum distance that can be performed above CS (D'). The data were analyzed using repeated measures ANOVA, correlation coefficients and multiple regression. VO2max (L.min(-1)) changed during the year, being higher in October (5.0 L.min(-1), P<0.01) and January (5.0 L.min(-1), P=0.01), than in April (4.7 L.min(-1)). There were no changes in the other laboratory measures during the study. Total distance covered in training changed during the year, being higher in January-February (474 km) than May-July (333 km; P=0.01) and July-August (339 km; P=0.02). Total distance covered in the training period preceding the laboratory test correlated with LT and running economy (r=0.55, P<0.01; r=-0.33, P=0.01). CS changed during the year (P=0.02), being at its lowest in August (4.90 m.s(-1)) and reaching a peak in February (4.99 m.s(-1)). There were no differences in D' across the study (P=0.11). Total training distance and percentage of training time spent above threshold velocity explained 33% of the variation in CS. Increasing training distance and the percentage of training time above threshold velocity was shown to increase CS.