Sunday, January 13, 2013

Hill Sprints and Running Economy: Review (Part 1)

     Last semester I started working on a project proposal that would investigate what effect 10 weeks of uphill sprint repetition training (hill sprints) would have on running economy. This will be a two-part post. My introduction is below, followed by a few (hopefully) thought provoking comments. Next week I will be posting my review of literature.

Chapter 1
Introduction

Distance running performance relies upon many variables.  For trainable attributes, coaches and athletes often assume the variables of maximum oxygen consumption (VO2max), anaerobic capacity, and lactate threshold are the major determinants of an athlete’s performance.  As stated by Noakes (1988), VO2max is so frequently discussed in lay articles that it seems most runners, swimmers, triathletes and cyclists believe that it is the most important predictor of athletic ability.  Indeed, VO2max and the other aforementioned variables are important for distance runners, but there is another critical component that contributes to an athlete’s performance; the variable of running economy (RE).  RE is defined as the steady state VO2, or energy demand, for a given velocity of submaximal running. RE is quantified by calculating the steady-state VO2 with respect to body mass and time for any given submaximal running speed (Morgan, Martin, & Krahenbuhl, 1989).  An improvement in RE would be indicated by a reduction of steady state oxygen consumption at a certain velocity of running.  Therefore, more economical runners are able to maintain a greater velocity while consuming less O2 and expending less energy.  The more economical runner may also be able to utilize fatty acids as fuel at high work rates, sparing carbohydrate (J. T. Daniels, 1985; Philo U. Saunders, D. B. Pyne, R. D. Telford, & J. A. Hawley, 2004a).  This would allow an athlete to not only run faster, but also extend that faster pace over a longer distance.

Significance of Running Economy
A strong association has been found between running economy and distance running performance.  In fact, research suggests that RE is a better predictor of performance than VO2max alone in runners with similar VO2max values (J. T. Daniels, 1985; McCann & Higginson, 2008; Noakes, 1988; Saunders et al., 2004a).  Because VO2max values of elite runners are generally similar, a difference in running economy between athletes could be the deciding factor in the outcome of a race.  Despite evidence demonstrating running economy’s importance to performance, to date there are few studies documenting training methods that improve running economy in highly trained distance runners.

Improving Running Economy
Some evidence indicates that running economy can be improved with resistance and/or plyometric training but the exact mechanism(s) behind the improvement is unknown (Foster & Lucia, 2007; Jung, 2003; McCann & Higginson, 2008; Saunders et al., 2004a).  It has been proposed that improvements in economy from resistance training are the result of improved neuromuscular characteristics such as motor unit recruitment and decreased ground contact time (Jung, 2003).

Resistance Training
While traditional resistance training has been shown to improve running economy, the techniques and lifts often employed (e.g. squats, leg extension, leg press, leg curls) cannot mimic the running stride.  Specificity of resistance training has been well documented.  It is known that resistance exercises will elicit effects on the specific muscles activated at or near the specific speeds and ranges of motion which the resistance exercises are performed (Morrissey, Harman, & Johnson, 1995).  Therefore, the more running specific a resistance training program, the better the results for running. Additionally, resistance training may improve RE in short term studies, but long term effects have not been investigated.  It is possible that weight gain associated with hypertrophy from long term resistance training could negatively impact RE (Midgley, McNaughton, & Jones, 2007).

Plyometric Training
In comparison to resistance training, plyometric training may be able to better simulate the kinematics of running and elicit a more specific response for the runner.  A number of studies have found plyometric training to improve RE (Paavolainen, Hakkinen, Hamalainen, Nummela, & Rusko, 1999; Saunders et al., 2006; Turner, Owings, & Schwane, 2003).  Like resistance training, plyometric training is also thought to improve neuromuscular motor unit recruitment but plyometric training may also increase the stiffness of the muscle-tendon system.  This allows the muscles to store and utilize elastic energy more effectively (Saunders et al., 2006; Spurrs, Murphy, & Watsford, 2003).  While plyometric training has shown to effectively improve RE in highly trained runners, and the movements used (e.g. bounding, hopping, and jumping) are more specific to running than traditional resistance training, there is no movement more specific to running than running itself.

Statement of the Problem 
Uphill running effectively adds resistance to movement, adding resistance very specifically to the running stride.  Uphill bounding and running have been used by coaches and athletes in attempts to increase distance runners’ strength and economy.  It has been suggested that high-velocity running exerts similar training effects as resistance training in distance runners such as improved motor unit recruitment (Midgley et al., 2007).  Potentially, adding resistance in the form of a hill to very high effort running could result in a response similar to that seen after plyometric and resistance training in the specific muscles used during running. While a number of lay publications and coaches today advocate the use of uphill running for strength their rationale is based solely on anecdotal evidence.  To date, no research has investigated the effects of high intensity uphill sprint training on RE.  Therefore the purpose of this study is to determine the effect of high intensity uphill sprints on RE in highly trained runners.

Significance of this Study
Relatively few interventions have been shown to improve RE in highly trained runners. If uphill sprint repetitions are found to improve RE, this will give coaches and athletes another means of potentially improving running performance. Further, this study will serve to justify or reject the current use of uphill sprint repetitions by coaches and athletes.  Further research would be necessary to confirm what distance, intensity, frequency, and grade of uphill work best for improving RE.



References


Daniels, J. T. (1985). A physiologist's view of running economy. Medicine & Science in Sports & Exercise, 17(3), 332-338.
Foster, C., & Lucia, A. (2007). Running Economy. Sports Medicine, 37(4/5), 316-319.
Jung, A. P. (2003). The impact of resistance training on distance running performance. . Sports Medicine, 33(7), 539-552.
McCann, D. J., & Higginson, B. K. (2008). Training to Maximize Economy of Motion in Running Gait. Current Sports Medicine Reports (American College of Sports Medicine), 7(3), 158-162.
Midgley, A. W., McNaughton, L. R., & Jones, A. M. (2007). Training to Enhance the Physiological Determinants of Long-Distance Running Performance. Sports Medicine, 37(10), 857-880.
Morgan, D. W., Martin, P. E., & Krahenbuhl, G. S. (1989). Factors affecting running economy. Sports Medicine, 7(5), 310-330.
Morrissey, M. C., Harman, E. A., & Johnson, M. J. (1995). Resistance training modes: specificity and effectiveness. Medicine & Science in Sports & Exercise, 27(5), 648-660.
Noakes, T. D. (1988). Implications of exercise testing for prediction of athletic performance: a contemporary perspective. Medicine & Science in Sports & Exercise, 20(4), 319-330.
Paavolainen, L., Hakkinen, K., Hamalainen, I., Nummela, A., & Rusko, H. (1999). Explosive-strength training improves 5-km running time by improving running economy and muscle power. Journal of Applied Physiology, 86(5), 1527-1533.
Saunders, P. U., Pyne, D. B., Telford, R. D., & Hawley, J. A. (2004). Factors affecting running economy in trained distance runners. Sports Med, 34(7), 465-485.
Saunders, P. U., Telford, R. D., Pyne, D. B., Peltola, E. M., Cunningham, R. B., Gore, C. J., & Hawley, J. A. (2006). SHORT-TERM PLYOMETRIC TRAINING IMPROVES RUNNING ECONOMY IN HIGHLY TRAINED MIDDLE AND LONG DISTANCE RUNNERS. Journal of Strength & Conditioning Research (Allen Press Publishing Services Inc.), 20(4), 947-954.
Spurrs, R. W., Murphy, A. J., & Watsford, M. L. (2003). The effect of plyometric training on distance running performance. European Journal of Applied Physiology, 89(1), 1-7.
Turner, A. M., Owings, M., & Schwane, J. A. (2003). Improvement in running economy after 6 weeks of plyometric training. J Strength Cond Res, 17(1), 60-67.





     The basis of this study came from reading Brad Hudson and Matt Fitzgerald's book, Run Faster: From the 5k to the Marathon. I'd done hill sprints in my years running cross country and track at Berry College and had never given them any more thought than what my coach and Hudson had said or written about them. Hudson, a former coach of Dathan Ritzenhein and founder of Hudson Training Systems states, " [Hill sprints] increase the power and efficiency of the stride, enabling the runner to cover more ground with each stride with less energy in race circumstances." In a roundabout way, Hudson claims that hill sprints improve running economy. Hudson goes on the state that hill sprints are, "not much different from a set of explosive Olympic weightlifting exercises... except more running specific."

     Hudson is not the first to incorporate hill sprints into his athletes' training. The Italian coach Renato Canova, who now coaches some of the world's best marathoners, has long been an advocate of hill sprints. And Canova admits he got the idea of hill sprints from the American sprint coach Bud Winter who began using hill sprints in the late 1960's. The Kiwi Arthur Lydiard was also using hill training in the 60's. My point being, using hills as a means of increasing a runner's strength is not a new concept. However, to my knowledge, no studies have assessed hill sprint training's effectiveness at increasing strength or economy. All the information we have is anecdotal. 

     Despite the lack of controlled studies, hill sprint training is quite popular. A quick Google search will turn up hundreds, if not thousands, of results touting the benefits of hill sprints from sites like Joggers Runners' World and Competitor -- they're the best thing since sliced bread, they increase strength, power, and running economy. So, you see the problem... All of these claims with no evidence to back them. Clearly, there is a knowledge gap between the coaches/athletes and the academic arena.

There are other aspects of hill training and I hope to address those in the weeks to come. I'd appreciate any comments on the topic or suggestions for new blog posts.

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