Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Cycling efficiency (efficiently)

10,186 views

Published on

Webinar for USA Cycling Coaching Education program.

Published in: Sports, Technology
  • Hey guys! Who wants to chat with me? More photos with me here 👉 http://www.bit.ly/katekoxx
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here

Cycling efficiency (efficiently)

  1. 1. Cycling efficiency (efficiently): what does it really mean? Andrew R. Coggan, Ph.D. Cardiovascular Imaging Laboratory Washington University School of Medicine St. Louis, MO 63110
  2. 2. Cycling efficiency • • • • • What is it? How do you measure it? Why is it important? What determines it? How do you train it?
  3. 3. Cycling efficiency – what is it? Definition • The same as in other scientific fields, e.g., physics: energy out/energy in x 100% Related concepts • Net efficiency, delta efficiency, economy
  4. 4. Cycling efficiency – how do you measure it? • Only one way to do so: → by using a metabolic chamber or cart to quantify energy liberation via direct or indirect calorimetry while simultaneously measuring power output using a cycle ergometer (or bicycle-mounted power meter).
  5. 5. Direct versus indirect calorimetry
  6. 6. Sample calculation of efficiency • Power (energy out) = 159 W (159 J/s) • VO2 = 2.16 L/min • RER = 0.82 • Energy in = 2.16 L/min x 4.825 kCal/L x 4184 J/kCal x 1 min/60 s = 728 J/s • Efficiency = energy out/energy in x 100% • Efficiency = 159 J/s x 1/728 J/s x 100% = 21.8%
  7. 7. Effect of absolute power output on gross efficiency
  8. 8. Cycling efficiency – why is it important? • Cycling efficiency represents the link between ATP turnover and external power output. • Thus, for a given metabolic rate a more efficient individual will be able to produce more power, and/or will be able to produce a given power output at a lower metabolic rate (= less physiological strain).
  9. 9. Effect of cycling economy on performance (“hour power”) Horowitz, Sidossis, and Coyle. Int J Sports Med 1994; 15:152-157
  10. 10. Variations in efficiency in world class cyclists Lucia et al. Med Sci Sports Exerc 2002; 34:2079-2084
  11. 11. Cycling efficiency – what determines it? Biomechanical factors • • • • • Saddle height Cadence (speed of muscle shortening) Not crank length Not fore-aft position of foot Not pattern of force application Biochemical factors • Muscle fiber type • UCP3 • SERCA1/SERCA 2
  12. 12. Biomechanical factors
  13. 13. Effect of saddle height on efficiency Price and Donne J Sports Sci 1997; 15:395-402
  14. 14. Effect of cadence on economy Hagberg et al. J Appl Physiol 1981; 51:447-451
  15. 15. Effect of crank length on efficiency McDaniel et al. J Appl Physiol 2002; 93:823-828
  16. 16. Effect of foot position on economy Sickle and Hull J Biomech 2007; 40:1262-1267
  17. 17. The classic “clock diagram” of pedaling forces
  18. 18. Evidence that increasing mechanical effectiveness does not improve cycling efficiency • Theoretical considerations – Role of uniarticular and biarticular muscles (Kautz and Neptune Exerc Sports Sci Rev 2002; 30:159-165) • Cross-sectional observations – On average, pattern of force application very similar in trained and untrained persons (Morneiux et al. Int J Sports Med 2008; 29:817-822)
  19. 19. Pattern of force application in elite cyclists vs. non-cyclists Mornieux et al. Int J Sports Med 2008; 29:817-822
  20. 20. Evidence that increasing mechanical effectiveness does not improve cycling efficiency • Theoretical considerations – Role of uniarticular and biarticular muscles (Kautz and Neptune Exerc Sports Sci Rev 2002; 30:159-165) • Cross-sectional observations – On average, pattern of force application very similar in trained and untrained persons (Morneiux et al. Int J Sports Med 2008; 29:817-822) – Inverse relationship between min:max torque and gross (R2 = -0.72; P<0.001) or delta (R2 = -0.76; P<0.001) efficiency (Edwards et al. J Sports Sci 2009; 27:319-325) – Individuals can be very efficient despite unusual pattern of force application (continued)
  21. 21. Unusual pattern of force application in a champion cyclist (rider 2)
  22. 22. Evidence that increasing mechanical effectiveness does not improve cycling efficiency • Longitudinal (interventional) observations – Removing toe-clips and cleats does not reduce efficiency (Coyle et al. J Appl Physiol 1988; 64:2622-2630, Ostler et al. J Sports Sci 2008; 26:47-55) – Training using uncoupled cranks does not improve efficiency (Bohm et al. Eur J Appl Physiol 2008; 103:225-232, Williams et al. Int J Sports Physiol Perform 2009; 4:18-28) – Acutely altering pedal stroke to be “rounder” reduces efficiency (Korff et al. Med Sci Sports Exerc 2007; 39:991-995)
  23. 23. Effect of pattern of force application on efficiency Korff et al. Med Sci Sports Exerc 2007; 39:991-995
  24. 24. Effect of pattern of force application on efficiency Korff et al. Med Sci Sports Exerc 2007; 39:991-995
  25. 25. Biochemical factors
  26. 26. Effect of fiber type on efficiency Coyle et al. Med Sci Sports Exerc 1992; 24:782-788
  27. 27. Effect of UCP3 on efficiency Mogensen et al. J Physiol 2006; 571.3:669-681
  28. 28. Effect of training on P:O ratio Mogensen et al. J Physiol 2006; 571.3:669-681
  29. 29. Effect of training on SERCA1/SERCA2 and efficiency Majerczak et al. J Physiol Pharmacol 2008; 59:589-602
  30. 30. Cycling efficiency – how do you train it?
  31. 31. Cycling efficiency – can it be trained?
  32. 32. Cross-sectional studies of cycling efficiency No difference • • • • • Boning et al. Int J Sports Med 1984; 5:92-97 Marsh and Martin Med Sci Sports Exerc 1993; 25:1269-1274 Nickleberry and Brooks Med Sci Sports Exerc 1996; 28:1396-1401 Marsh et al. Med Sci Sports Exerc 2000; 32:1630-1634 Mosely et al. Int J Sports Med 2004; 25:374-379 Higher in trained cyclists • • Sallet P et al. J Sports Med Fitness 2006; 46:361-365 Hopker et al. Appl Physiol Nutr Metab 2007; 32:1036-1042
  33. 33. Longitudinal studies of cycling efficiency No change • Roels et al. Med Sci Sports Exerc 2005; 37:138-146 Increases with training • • • • • • • Hintzy et al. Can J Appl Physiol 2005; 30:520-528 Paton and Hopkins J Strength Cond Res 2005; 13:826-830 Majerczak et al. J Physiol Pharmacol 2008; 59:589-602 Sassi et al. Appl Physiol Nutr Metab 2008; 33:735-742 Hopker et al. Med Sci Sports Exerc 2009; 41:912-919 Hopker et al. Appl Physiol Nutr Metab 2010; 35:17-22 Sunde et al. J Strength Cond Res 2010 (in press)
  34. 34. Cycling efficiency – how do you train it? • “Ordinary” training apparently results in a small, but significant, improvement in cycling efficiency. However, whether efficiency continues to improve over many years or merely oscillates in/out of season around some average value is still uncertain. (continued)
  35. 35. Cycling efficiency – how do you train it? (con’t) • Additional improvements might be obtained via “special techniques”, i.e.,: – High intensity training – – – Paton and Hopkins J Strength Cond Res 2005; 13:826-830 Hopker et al. Med Sci Sports Exerc 2009; 41:912-919 Hopker et al. Appl Physiol Nutr Metab 2010; 35:17-22 – Training in hypoxia – – Gore et al. Acta Physiologica Scandinavica 2001; 173:275286 Katayama et al. High Alt Med Biol 2003; 4:291-304 – Resistance training – Sunde et al. J Strength Cond Res 2010 (in press)
  36. 36. Key Points Cycling efficiency  Is defined as energy out/energy in x 100%;  Can only be determined via use of direct or indirect calorimetry in conjunction with power measurements;  Represents the link between cellular energy “production” and actual performance (i.e., power); (continued)
  37. 37. Key Points (continued) Cycling efficiency  Can vary significantly between individuals, even among world class cyclists;  Is apparently determined by both biomechanical (i.e., saddle height, cadence) and biochemical (i.e., fiber type, SERCA activity) factors;  Is either not related to, or is even inversely related to, mechanical effectiveness; (continued)
  38. 38. Key Points (continued) Cycling efficiency  Improves as a function of “ordinary” endurance training;  Might be further increased with very prolonged and/or very intense training, and/or as a result of hypoxia or resistance training

×