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PERFORMANCE BASED MEASURES OF RECOVERY IN POWER

OVERVIEW. Definitions Where are we at? Central measures of fatigue Peripheral measures of fatigue Summation Research suggestions References. DEFINITIONS. Central fatigue

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PERFORMANCE BASED MEASURES OF RECOVERY IN POWER

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    1. PERFORMANCE BASED MEASURES OF RECOVERY IN POWER/SPEED SPORTS

    2. OVERVIEW Definitions Where are we at? Central measures of fatigue Peripheral measures of fatigue Summation Research suggestions References

    3. DEFINITIONS Central fatigue – insufficient neural drive to the muscles (Garrandes et al. 2005) Peripheral fatigue – changes beyond the neuromuscular junction (Garrandes et al. 2005) Neural plasticity - the process whereby patterns of impulses into mature synapses can cause long-lasting changes in the magnitude of the subsequent stimulation (Armstrong & VanHeest, 2002)

    4. WHERE ARE WE AT? Most research has concentrated on metabolic & biochemical markers Neural processes are not well understood, particularly how they respond to exercise Techniques to measure NCV, neural drive & reflex response need consistency & refinement Most research admits difficulty in differentiating between central & peripheral fatigue Markers showing promise include power decrement, EMG:force ratio, reflex inhibition, NCV

    5. CENTRAL MEASURES Noakes (2000): Brain [neurotransmitter] alters rate coding during exercise CNS deactivates as a protective mechanism (some support for this theory) Hautier et al. (2000) – constant EMG:force ratio concurrent with force decrease Ross et al. (2001) – NCV is promising Koceja et al. (2004) – Hmax:mmax ratio Reflex sensitivity – most support in literature but can be affected by metabolic by-products CMJ – research inconclusive but promising

    6. PERIPHERAL MEASURES High frequency model– impaired AP propagation along muscle fibre Paasuke et al. (1999) – electromechanical delay Glaister et al. (2005) - metabolic acidosis is not a limiting factor in excitation-contraction coupling (no EMG) Jereb and Strojnik (2003) – imbalance of [Na+] & [K] impair AP propagation

    7. SINGLE-LEG HOP STUDY

    8. SUMMARY Trial & error with a combination of markers (ie PT reflex inhibition & power decrement) Power decrement assessment is simple & results are immediate (event implications) The central v’s peripheral debate appears academic (what are the practical implications?) Consider neural plasticity v’s fatigue for different sports & individuals

    9. RESEARCH SUGGESTIONS Correlations between biochemical & neural markers More studies using trained subjects & dynamic fatigue protocols Efficacy of simple reaction-time tests in the field Validity of field measures (single-leg hop) compared to lab tests

    10. REFERENCES 1. Armstrong, L.E. and VanHeest, J.L. The unknown mechanism of the overtraining syndrome. Clues from depression and psychoneuroimmunology. Sports Med. 32(3):185-209, 2002. 2. Garrandes, F., Colson, S.S., Pensini, M. and Legros, P. Neuromuscular fatigue kinetics are sport specific. Computer Methods in Biomechanics and Biomedical Engineering. Supplement 1:113-114, 2005. 3. Augustsson, J., Thomee, R., Linden, C., Folkesson, M., Tranberg, R. and Karlsson, J. Single-leg hop testing following fatiguing exercise: reliability and biomechanical analysis. Scandinavian Journal of Medicine and Science in Sports. 16:111-120, 2006. 4. Hautier, C.A., Arsac, L.M., Deghdegh, K., Souquet, J., Belli, A. and Lacour, J. Influence of fatigue on EMG/force ratio and cocontraction in cycling. Medicine and Science in Sports and Exercise. 32(4):839-843, 2000. 5. Koceja, D.M., Davison, E. and Robertson, C.T. Neuromuscular characteristics of endurance-and power-trained athletes. Research Quarterly for Exercise and Sport.75(1):23-30, 2004. 6. Noakes, T.D. Physiological models to understand exercise fatigue and the adaptations that predict or enhance athletic performance. Scandinavian Journal of Medicine and Science in Sports. 10:123-145, 2000. 7. Paasuke, M., Ereline, J. and Gapeyeva, H. Neuromuscular fatigue during repeated exhaustive submaximal static contractions of knee extensor muscles in endurance-trained, power-trained and untrained men. Acta Physiol Scand. 166:319-326, 1999. 8. Ross, A., Leveritt, M. and Riek, S. Neural influences on sprint running. Training adaptations and acute responses. Sports Med. 31(6):409-425, 2001. 9. Jereb, B. and Strojnik, V. Neuromuscular fatigue after short maximal cycling exercise. Kinesiology. 35(2):135-142, 2003. 10. Glaister, M., Stone, M., Stewart, A.M., Hughes, M. and Moir, G.L. The influence of recovery duration on multiples sprint cycling performance. Journal of Strength and Conditioning Research. 19(4):831-837, 2005.

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