Limiting factors of performance in elite adolescent middle-distance runners

Introduction

The relationship between endurance running performance and physiological variables in adolescents has been examined in few studies (1,2). VO2max, energy cost, ventilatory threshold, lactate threshold, anaerobic power are the more frequent parameters studied in young people to explain variation in middle distance running performance. No study has analysed the importance of other possible indicators of performance such as maximal accumulated oxygen deficit (MAOD) and oxygen kinetics (O2onset). The purpose of this study is in fact to investigate the relationship between 1000m performance time and a number of physiological variables in a group of adolescent runners.

Methods

8 elite adolescent girls (14.63±0.74 years) volunteered to participate in the study. Track-based, running performance time for the 1000m was correlated with the following physiological variables measured in a laboratory setup: muscular explosive power with the Jump test (Counter movement jump, CMJ) and Bosco test (15s), Optojump, Microgate, Italy; maximal oxygen consumption (VO2max), lactate anaerobic threshold (V’ slope, Wasserman), energy cost (EC), O2onset, blood lactate/speed curve with speed at 2,3,4,mM (LAT 2,3,4 mM) and MAOD with different testing protocols performed on treadmill, Technogym, Italy. An incremental running test to exhaustion allowed the VO2max and V’ slope measurement. Breath-by-breath VO2 data (Quark b2, Cosmed, Italy), collected at a workload under anaerobic threshold (70% VO2max), were used to analyse EC and O2onset. LAT at 2,3,4 mM was evaluated (Biosen 5030, EKF, Germany) with an incremental test during which each step was lasting 5 minutes. For the MAOD test, subjects were required to run on the treadmill at supramaximal speeds until volitional exhaustion.

Results

A significant negative correlation existed between speed at V’ slope and peak blood lactate concentration (maxLAT) and performance (r=-0.708,-0.686 respectively, p<0.05). Run performance at 1000m was influenced by a considerably different set of variables: speed at 3 mmol (v3) and speed at V’ slope, maximal speed during graded test, maxLAT, CMJ, Bosco 15s. The speed at V’ slope and v3 accounted for around 52,5% of the variability in performance, whereas other physiological variables selected in this study were responsible, at best, for approximately 18,3% (maxLAT, Bosco 15s). No significant relationship was found between 1000m run time and VO2max, energy cost, MAOD and onset.

Conclusion

The physiological variable that most limited 1000m run performance in elite adolescent athletes was the speed at V’ slope. This finding is supported by another study which analysed trained middle distance runners (3). The major influence of aerobic metabolism can be due to the young age of studied runners that have not yet developed anaerobic qualities. The results of the present study support the conclusions of other investigations that question the validity of the MAOD as a predictor of performance (4). Therefore, other researchers working with middle-distance runners may wish to consider O2onset in future study, perhaps choosing a shorter performance, lasting less than 4 minutes. For training purpose, we cannot also forget the influence of anaerobic power.

References

1. Ali Almarwaey O. et al. (2003), Med Sci Sports Exerc, Mar, 35(3), 480-7
2. Abe D. et al. (1998), Eur J Appl Physiol Occup Physiol, Mar, 77(4), 320-5
3. Zacharogiannis E. & Farrally M. (1993), J Sports Med Phys Fitness, Dec, 33(4), 337-47
4. Craig IS. & Morgan DW. (1998), Med Sci Sports Exerc, Nov, 30(11), 1631-6