Monday, January 27, 2014

Nutritional considerations to performance: Beet juice and Nitrate supplementation

 By: Grant Harrison, MS. Source Endurance Senior Consultant

When you look back at how you won your last race, you probably think about all the hard work in training that led you up to that point, how well you and your teammates read the race, or perhaps a tactically sound move that put you atop the podium. We are quick to give credit to the more tangible elements to training and racing but what about our diet? Most of us have never said, “My diet was awesome, my teammates put me in a good spot to win, and my training was effective,” right?
On a daily basis, the types, quantities, and qualities of foods we eat have an effect on the intensities or durations at which we are able to train and race. Most cycling and endurance sport athletes have a good understanding of how to fuel their workouts and how to be good stewards to their body through diet. That said, the importance of proper nutrition and supplementation should not be undermined as optimal performance hinges on a balanced diet and proper supplementation.  Nutritional supplements have made their way into endurance sports as we understand how many of them directly affect how well we are able perform.

Recently, an emerging body of research has looked at the effectiveness of beetroot juice and/or nitrate supplementation as a way to improve performance. As dietary nitrate supplementation has shown to reduce resting blood pressure. Dietary nitrates have also shown to increase muscle blood flow, regulation of muscular contractions, glucose uptake, and cellular respiration.
Building upon these findings, recent research has focused on how dietary nitrate supplementation may improve sub-maximal exercise, sever maximal exercise, and exercise at altitude.

During sub-maximal intensity exercise, the effects of a 6-day nitrate supplementation have shown reduced VO2 (volume of oxygen consumed) when compared to a nitrate deficient placebo. What this means is that our muscles are more efficient at producing energy aerobically and therefore are able to perform more work at any given sub-maximal level of oxygen consumption. Figure 1. shows the data collected by Muggeridge, et al. (2014)

The same study had participants perform a 10-Km time trial under the same conditions as time to completion and power were measured across the placebo and nitrate supplementation groups. The results of the study showed significant differences in both power and time to completion between the two groups (Figure 2.).

Another study conducted by Kelly, J., Vanhatalo, A., Wilkerson, D., Wylie, L., and Jones, A., (2013), also analyzed the effects of nitrate supplementation on four different severe-intensity exercise bouts all to exhaustion. Three of the four exercise bouts elicited a significant difference between the nitrate supplementation group and the placebo group (figure 3.) with the most intense exercise bout not showing statistical significance though an improvement was observed for the nitrate supplement group.

The results from these studies should give athletes a solid reason to investigate the performance benefits of beetroot juice and/or nitrate supplementation. Like any other product, the consumer should seek out a product that works best for them with the least amount of drawbacks. Given the apparent scientific consensus that beetroot juice and nitrate supplements lead to increases in performance, it would be expected that many endurance athletes will use dietary nitrate products not only in acute doses, but as a regular staple to improve overall health and effectiveness of training. Finally, Muggeridge, D., et al (2014), propose that NO- production as a direct consequence of dietary nitrate supplementation may offset the
reduction in NO- during hypoxia and minimize the negative consequences on exercise performance at altitude. Muggeridge also contends that individuals living in low altitude locations would seek the most benefit from supplementing as NO- levels tend to be elevated in high-altitude dwellers.

As many products exist on the market for this supplement, Source Endurance client Chris Lowry of La Crosse, WI has been enjoying the benefits of beetroot in its organic form. Lowry incorporates an amino acid blend with raw organic juiced beets and other fruits before and after his workouts.

Cermak, N., Gibala, M., & Van Loon, L., (2012). Nitrate Supplementation's Improvement of 10-km time-trial performance in trained cyclists. International Journal Of Sport Nutrition & Exercise Metabolism, 22(1), 64-71.

Kelly, J., Vanhatalo, A., Wilkerson, D. P., Wylie, L. J., & Jones, A. M. (2013). Effects of nitrate on the power-duration relationship for severe-intensity exercise. Medicine & Science In Sports & Exercise, 45(9), 1798-1806.

Larsen F., Ekblom B., Sahlin K., Lundberg J., Weitzberg E. (2006) Effects of dietary nitrate on blood pressure in healthy volunteers.The New England Journal of Medicine, 355:2792–3.

Muggeridge, D., F. Howe, C., Spendiff, O., Pedlar, C., James, P., & Easton, C., (2014). A single dose of beetroot juice enhances cycling performance in simulated altitude. Medicine & Science In Sports & Exercise, 46(1), 143-150.

Stamler JS, Meissner G. (2001) Physiology of nitric oxide in skeletal
muscle. Physiology Review. 81:209–37.

Webb A., Patel N., Loukogeorgakis S., et al. (2008) Acute blood pressure
lowering, vasoprotective, and antiplatelet properties of dietary

nitrate via bioconversion to nitrite. Hypertension, 51:784–90.

Tuesday, January 21, 2014

Compression Garments: The Verdict

By: John Hobbs, MS. Source Endurance Senior Consultant

While most of the data indicate that the use of compression garments does not provide an advantage, there are a handful that do show possible benefits.  It is important, however, to tease out the possible causes and evaluate the efficacy of the items.

                For instance, Bringard, Perrey and Reaburn (2006) found that running economy may be improved with the use of compression stocking during exercise.  However, this study was done with athletes running at 80% of VO2max with no performance measurements.  Additionally, the cause for the change in economy could not be attributed to a specific mechanism. 

                Another example are the decreased levels of creatine kinase that have been reported with the use of compression garments (Dufield and Portas 2007).  What exactly does this mean?  Basically, creatine kinase is an enzyme only found inside cells.  When a muscle becomes damaged, some of the contents are released in to the blood.  As a result, levels of enzymes normally found in the cells increases in the circulation.  Creatine kinase measurements are often used to help diagnose a heart attack.  When the heart muscle is damaged, the levels of the enzyme specific to cardiac muscle spike.  The same principal applies to muscle damaged with exercise.  In the cited study, the cricket players wore the garments during and after exercise.  As a result, it cannot be distinguished if the decreased creatine kinase levels is a result of improved blood flow, and therefore clearance of the enzyme, or a decrease in muscle damage through some other mechanism, preventing a possible increase from even occurring.  Additionally, the difference in enzyme levels is not consistently seen when compression garments are implemented (Jakeman, Byrne, & Eston 2010; Duffield et al, 2008; Duffield, Cannon, & King, 2010).  This, coupled with the fact that no differences in lactic acid and muscle pH at various time periods after exercise (Duffield et al., 2008) indicate that the use of compression stockings does not alter circulation to provide a recovery benefit.

                Another more commonly reported benefit of wearing compression garments is a decreased perceived muscle soreness (Dufield & Portas 2007; Jakeman, Byrne, & Eston 2010; Pruscino, Halson, & Hargreaves 2013; Ali, Cane & Snow 2008).  This has several implications.  First, the mechanism by which delayed onset muscle soreness occurs can cause a decrease in muscle force generation for up to two weeks.  This can have effects on future performance if events are scheduled close together as well as the ability to perform workouts if maximal efforts are required.  Jakemen, Byrne, and Eston (2010) added evidence to this recovery benefit with data showing that exercise performance benefited with compression garments worn in recovery.  It must be noted, however, the study participants were active, exercising three times a week, but not well trained athletes.  This leads to questioning if the gain was seen due to the training status, especially when coupled with the other cited studies that found  decreased muscle soreness as the only benefit.  Additionally, Dufield, Cannon, and King (2010) found that there were no differences in muscle twitch properties when the garments are worn for recovery, essentially showing that while the individual feels less sore, there is actually no change in performance .  With this however, these still is a benefit if perceived soreness is decreased.  Psychologically, an athlete may be better off.  For instance, a stage racer may be more aggressive or have better planning in pre-race preparation if they are less sore.  Additionally, the motivation to complete hard workouts can lack at times, especially with fatigue. Increased muscle soreness may affect adherence to an athlete’s training plan.  While, this benefit is not physiological or directly related to performance, it is still a benefit.

                The extent to which these garments have been evaluated is well beyond the scope of these articles.  Additional studies showing possible benefits have been published along with data further discounting the efficacy of compression garments in endurance athletes.  Understanding the physiological mechanism of action as well as the population the compression stockings were originally applied to can assist a person in understanding why the use of the garments likely does not provide a benefit to healthy athletes.

Ali, A., Caine, M., & Snow, B. (2007).  Graduated compression stockings: Physiological and perceptual responses during and after exercise. Journal of Sports Sciences, 25(4): 413 – 419
Bringard, A., Perrey, S., & Belluye, N. (2006).  Aerobic energy cost and sensation responses during submaximal running exercise –positive effects of wearing compression tights.  Int J Sports Med 2006; 27: 373–378

Duffield, R., Cannon, J., King, M. (2010).  The effects of compression garments on recovery of muscle performance following high-intensity sprint and plyometric exercise.  Journal of Science and Medicine in Sport 13 (2010) 136–140

Duffield, R., Edge, J., Merrells, R., Hawke, E., Barnes, M., Simcock, D., & Gill, N. (2008).  The Effects of Compression Garments on Intermittent Exercise Performance and Recovery on Consecutive Days.  International Journal of Sports Physiology and Performance, 2008, 3, 454-468

Duffield, R., Portlus, M. (2007).  Comparison of three types of full-body compression garmentson throwing and repeat-sprint performance in cricket players.  Br J Sports Med 2007;41:409–414. doi: 10.1136/bjsm.2006.033753

Jakeman, J., Byrne, C., & Eston, R. (2010).  Lower limb compression garment improves recovery from exercise-induced muscle damage in young, active females.  European Journal of Applied Physiology, 109, Issue 6, pp 1137-1144

Montgomery, P., Pyne, D., Hopkins, W., Dorman, J., Cook, K., & Minahan, C. (2008).  The effect of recovery strategies on physical performance and cumulative fatigue in competitive basketball.  Journal of Sports Sciences, September 2008; 26(11): 1135–1145

Pruscino, C., Halson, S.,  & Hargreaves, M.  (2013). Effects of compression garments on recovery following intermittent exercise.  Eur J Appl Physiol (2013) 113:1585–1596 DOI 10.1007/s00421-012-2576-5

Scanlan, A., Dascombe, B.,  Reaburn, P.,  & Osborne, M. (2008). The Effects of Wearing Lower-Body Compression Garments During Endurance Cycling.  International Journal of Sports Physiology and Performance, 2008, 3, 424-438

Sperlich, B., Haegele, M., Achtzehn, S., Linville, J., Holmberg, H., & Mester, J. (2010).  Different types of compression clothing do not increase sub-maximal and maximal endurance performance in well-trained athletes.  Journal of Sports Sciences, 28, Issue 6, 2010