Author(s): DE LUCAS, R., LANZARINI, L.D.V., GONÇALVES, E.B., DALLA LANA, I. , Institution: FEDERAL UNIVERSITY OF SANTA CATARINA, Country: BRAZIL, Abstract-ID: 310

INTRODUCTION:
Self-paced interval training (IT-SP) is an effective and simple model for prescribing high-intensity training to athletes1. Pacing strategy can be considered the main challenge for athletes performing IT-SP, depending on the composition of the set (volume and rest periods). Based on the critical speed model, the distance above critical speed (D’) appears to be related to the tolerance of supra-critical speed exercises and, therefore, its early expenditure may influence pacing strategy2. This study aimed to examine the relationship between the depletion of D’ in the first repetition and the pacing strategy adopted during IT-SS.
METHODS:
20 trained runners (10M and 10F) completed the following tests: Incremental treadmill test to determine V̇O₂max and its corresponding speed (sV̇O₂max); Track time trials at distances of 800, 1500, and 3000 m to determine critical speed (CS) and D’; IT-SP session consisting of 6x 800 m intervals with 90 seconds of rest between the repetitions. Each test was interspaced by at least 48-h. During the IT-SS session, athletes were instructed to perform the highest possible average speed, leaving no “energy” to complete an extra repetition. Feedback on time, speed, or pace were not provided. Blood lactate (Lac) and rate of perceived exertion (RPE) were obtained during and at the end of the IT. Pacing strategy during IT-SS was assessed using the slope of a linear regression model, calculated from the average speed of each repetition and the repetition number.
RESULTS:
The average CS was 14.0 ± 1.5 km/h, while D’ was 182 ± 36m. The average speed of entire IT-SP was 15.1 ±1.5 km/h, representing 108 ± 4% of CS or 94 ± 5% of sV̇O₂max. During the first repetition, runners depleted an average of 47 ± 17 % of D’. There was found a negative and significant correlation (r= -0.88, p<0.001) between %D’ depleted during the first repetition and the pacing strategy of IT-SP (i.e. slope). Also, the RPE at the end of session was 19.5 ± 0.8 and Lac achieved 11.1 ± 3.9 mM, indicating that the IT-SP was performed at maximal effort for the proposed volume.
CONCLUSION:
The % depleted of D’ during the first repetition of the interval training session was sensible to detect differences in pacing strategy, showing that runners who self-paced the first repetition using a high %D’ presented a decrease in the average speed over the following repetitions. This sensibility may be related to the physiological disturbance caused by D’ expenditure, such as phosphocreatine depletion and fatigue-related metabolites production, increasing RPE and Lac. In this scenario, subjects consciously reduce their speed in order to finish the entire session and maintain the highest mean speed possible. This data suggest that CS model could be useful for controlling the pace at least during the first repetition for imposing a better maintenance of pacing during an IT in endurance runners.
References:
1. Edwards, A.M. et al. Psychophysiology, 2011.
2. Pettitt, R.W. Int J Sports Physiol Perform, 2016.