Metabolic conditioning can be considered as an overall umbrella term that encompasses all forms of aerobic and anaerobic based conditioning. Practitioners should ensure any applied metabolic conditioning based training matches the bio-energetic and sports specific demands of an athletes chosen sport whilst periodically training at a sub-maximal and supra-maximal level in-relation to these pre-determined sport demands. Metabolic conditioning based training comes in a variety of forms, one of which is repeated sprint ability.
RSA Demands of Sport
Russell et al (2016) previously investigated the movement demands of premiership soccer players and reported that players covered a mean total distance of 9.5km, a mean high intensity distance of 487 m, and a total of 656 accelerations per 90 minute game. Likewise, rugby league and union players are required to perform repeat high intensity efforts (acceleration, deceleration and changes of direction) including repeat high force collisions (tackles, scrums, etc.) (Till, Scantlebury and Jones, 2017). Spencer et al (2004) reported similar findings, with the mean number of repeat sprints being 4±1 sprints per high intensity bout within competitive elite field hockey. The authors also reported that 95% of the recovery during each repeated sprint was of an active nature.
Similar to the intermittent nature of team sports, racquet sports require athletes to perform repeat high intensity efforts throughout competitive play. However, the distance covered per sprint is reduced when compared to team sport movement demands due to the constrains of the size of the court. Pluim (2004) previously described tennis as an intermittent exercise, involving alternating short bouts of high intensity exercises lasting 4-10 seconds with short recovery periods of 10-20 seconds with several periods of longer duration activity of 60 to 90 seconds (rallies). These findings demonstrate the repeat sprint demands of team sports and racquet sports, and the need to replicate these demands with training, allowing for the favoured metabolic based adaptations associated with repeated sprint training.
Hydrogen Buffering Efficiency
The accumulation of lactate acid is often referred to as the main factor in diminishing power output and athlete performance. However, it appears that lactic acid itself may be accumulating in an attempt to buffer the accumulation of hydrogen ions that occurs during the process of anaerobic metabolism. The accumulation of hydrogen ions and inorganic phosphates has previously been shown to be key factors contributing to muscle fatigue in repeated sprint performance (Glaister, 2005). Both hydrogen ions and inorganic phosphates inhibit calcium’s effect to activate tropomyosin, therefore reducing the myosin – actin binding mechanism and cross bridge cycle rate. Edge et al (2006) previously reported that athletes with a high level of repeated sprint ability demonstrate a superior ability to buffer the accumulation of hydrogen ions associated with glycolytic metabolism. Therefore, it appears the ability to buffer hydrogen ions is a trainable adaptation in athletes, in addition to an increase in muscle glycolytic enzyme content and activity.
Lactate Shuttling
During the performance of high intensity efforts, skeletal muscle lactate transporters situated within the muscle membrane assist in the reduction of lactate accumulation. In particular, monocarboxylate transporters are critical in the removal of lactate and hydrogen ions. Bishop et al (2011) previously suggested that the responsiveness of monocarboxylate transporters maybe responsive to anaerobic based training methods involving repeated high intensity efforts. Furthermore, previous findings suggest that the transported lactate out of a muscle cell during high intensity training can be oxidised by the adjacent muscle fibres and used as a substrate for energy metabolism (Brooks 2009). Such increase in monocarboxylate transporter adaptations would contribute to an overall reduction in lactate and hydrogen accumulation and increase an athlete’s ability to ‘tolerate’ lactate and muscle buffering capabilities.
Enhanced Glycolytic Enzyme Activity
An athlete’s anaerobic capacity performance is dependent upon multiple factors, including glycolytic enzyme content and activity. This is due to the glycolytic demands of anaerobic based activity, which taxes the glycolytic energy pathways. Kubukeli et al (2010) previously suggested that the number and activity of glycolytic metabolism based enzymes increase in response to training that stresses an athlete’s anaerobic bio-energetic systems. Such anaerobic based adaptations would obviously favour an athlete’s repeated high intensity effort capabilities.
Such adaptations would favour athletes who require the ability to produce repeated high intensity efforts, therefore providing a sound rationale for the inclusion of anaerobic based training such as repeated sprint based training. The next article within this series will explore the programming of repeated sprint ability within sports performance and what factors should be considered when designing repeated sprint ability-based training (see ‘Repeated Sprint Ability Part II : Training Considerations).
Bishop, D. Girard, O. Mendez-Villanueva. (2011). Repeated sprint ability – Part II: Recommendations for training. Sport Medicine. 41(9): pp: 741-756.
Brooks, G, A. (2009). Cell-cell and intracellular lactate shuttles. Journal of physiology. 587, pp: 783-790.
Edge, J, D. Bishop, S. Hill-Haas, B. Dawson, Goodman, C. (2006). Comparison of muscle buffer capacity and repeated sprint ability of untrained, endurance-trained and team-sport athletes. European Journal of Applied Physiology. 96, pp: 225-234.
Glaister, M. (2005). Multiple sprint work: Physiological responses, mechanisms for fatigue and the influence of aerobic fitness. Sports Medicine. 35(9), pp: 757-777.
Kubukeli, Z, N. Noakes, T, D. Dennis, S, C. (2010). Training techniques to improve endurance exercise performance. Sports Medicine. 32(8), pp: 489-509.
Pluim, B. (2004). Physiological demands of the game. In: Pluim, B. Safran, M. Eds. From breakpoint to advantage: a practical guide to optimal tennis health and performance. Vista, CA: USRSA, pp. 17–23.
Russell, M. Sparkes, W. Northeast, J. Cook, C, J. Love, T, D. Bracken, R, M. Kilduff, L, P. (2016). Changes in acceleration and deceleration capacity throughout professional soccer match play. Journal of Strength and Conditioning Research. 30(10), pp: 2839–2844.
Spencer, M. Lawrence, S. Rechichi, C. Bishop, D. Dawson, B. Goodman, C. (2004). Time–motion analysis of elite field hockey, with special reference to repeated-sprint activity. Journal of Sports Sciences. 22, pp. 843–850.
Till, K. Scantlebury, S. and Jones, B. (2017). Anthropometric and physical qualities of elite male youth rugby league players. Journal of Sports Medicine. 47(11), pp. 2171-2186.
