Can quercetin improve endurance capacity?

Quercetin is a plant chemical that naturally occurs in many different fruits and vegetables. Red onions are one of the best sources of quercetin. It has demonstrated both anti-inflammatory, and anti-viral effects. But can it also help improve endurance capacity?

According to the University of South Carolina, Columbia, SC, in The dietary flavonoid quercetin increases VO(2max) and endurance capacity:

Seven days of quercetin feedings were associated with a modest increase in VO2max (3.9% vs. placebo; p < .05) along with a substantial (13.2%) increase in ride time to fatigue (p < .05). These data suggest that as little as 7 days of quercetin supplementation can increase endurance without exercise training in untrained participants. These benefits of quercetin may have important implications for enhancement of athletic and military performance. This apparent increase in fitness without exercise training may have implications beyond that of performance enhancement to health promotion and disease prevention.

Interesting! But this is just one study. Fortunately a meta-analysis(a study that combines the results of several studies) of the effects of quercetin was done by the Georgia Institute of Technology, Atlanta, GA, in Quercetin and endurance exercise capacity: a systematic review and meta-analysis:

CONCLUSIONS:

On average, quercetin provides a statistically significant benefit in human endurance exercise capacity (VO(2max) and endurance exercise performance), but the effect is between trivial and small. Experimental factors that explain the between-study variation remain to be elucidated.

There does appear to be an effect, but it’s small. More research needs to be done, but I won’t be eating lots of red onions just because of this.

Grapes versus blueberries for health

Not all fruit was created equal. Some are simply better than others when it comes to health benefits or exercise recovery. Generally, it seems the darker the fruit(or vegetable for that matter), the more beneficial. Hence the superiority of cherries and blueberries over grapes. Let’s see what the science has to say.

According to the Dept. of Kinesiology, University of Georgia, Athens, GA, in the study Grape Consumption’s Effects on Fitness, Muscle Injury, Mood, and Perceived Health:

Six weeks of supplemental grape consumption by recreationally active young adults has no effect on VO2max, work capacity, mood, perceived health status, inflammation, pain, or physical-function responses to a mild injury induced by eccentric exercise.

This doesn’t mean that grapes are bad, just that they aren’t among the better fruits. Let’s see what the science says for blueberries. The Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damagein the J Int Soc Sports Nutr. 2012; 9: 19 found that:

Results

A significant (p<0.001) decrease in isometric, concentric and eccentric torque was observed 12 hours following exercise in both treatment groups. During the 60 hour recovery period, a significant (p=0.047) interaction effect was seen for peak isometric tension suggesting a faster rate of recovery in the blueberry intervention group. A similar trend was observed for concentric and eccentric strength. An increase in oxidative stress and inflammatory biomarkers was also observed in both treatment groups following EIMD. Although a faster rate of decrease in oxidative stress was observed in the blueberry group, it was not significant (p<0.05) until 36 hours post-exercise and interestingly coincided with a gradual increase in plasma antioxidant capacity, whereas biomarkers for inflammation were still elevated after 60 hours recovery.

Conclusions

This study demonstrates that the ingestion of a blueberry smoothie prior to and after EIMD accelerates recovery of muscle peak isometric strength. This effect, although independent of the beverage’s inherent antioxidant capacity, appears to involve an up-regulation of adaptive processes, i.e. endogenous antioxidant processes, activated by the combined actions of the eccentric exercise and blueberry consumption. These findings may benefit the sporting community who should consider dietary interventions that specifically target health and performance adaptation.

Impressive. I’ll stick to eating blueberries instead of grapes for exercise recovery and for general health.

 

Exercise recovery is just a bowl of cherries

Source: Wikipedia

The delicious spring weather has just been so perfect these days, allowing me to push myself to run faster while juggling 3 balls, as well as slowly improving my 4 ball joggling. All this speed means more strain on my muscles and connective tissues, so I am always on the lookout for something or other to maximize my recovery. Juggling while running for an hour or more can produce a lot of inflammation throughout the body, which can damage muscle tissue and hinder the body’s innate healing response. All else being equal, a joggler is likely more inflammed and worn out than a mere runner so we need to be a little more careful to ensure proper recovery.

I’ll assume we all know to get enough water before, during, and after a workout, as well as refueling with carbs and protein within 30 minutes after exercise. I usually drink a lot of fruit juice after long runs, along with some nuts or protein powder or will simply have a meal if its meal time. I’ve long believed that the phytochemicals in various fruit and vegetable juices can assist in recovery, due to their ability to protect tissues from inflammatory processes and free radicals. This is partially due to their antioxidant effects, but as I’ve said in previous posts, a lot more is going on. So to me, recovery has long been more than simply getting macro-nutrients, electrolytes, and proper hydration.

Which brings us to cherry juice. Some interesting studies on cherry juice suggest it may help speed recovery from both marathon running and strength training. According to the School of Psychology and Sport Sciences, Northumbria University, Newcastle upon Tyne, UK, in their study, the Influence of tart cherry juice on indices of recovery following marathon running:

The cherry juice appears to provide a viable means to aid recovery following strenuous exercise by increasing total antioxidative capacity, reducing inflammation, lipid peroxidation and so aiding in the recovery of muscle function.

This sounds good enough to the point that I may drink cherry juice more often after workouts. Now I realize it’s good to be skeptical and cherry juice may not work for everyone, and maybe the study is flawed, but this is just cherry juice, so there is little risk involved. I’m also very curious to see if it will do anything for me. Even if it doesn’t, I love tartness.

Here’s a study on Montmorency cherries from the Sports and Exercise Science Research Centre, London South Bank University, London, United Kingdom, Montmorency cherry juice reduces muscle damage caused by intensive strength exercise:

Montmorency cherries contain high levels of polyphenolic compounds including flavonoids and anthocyanins possessing antioxidant and anti-inflammatory effects. We investigated whether the effects of intensive unilateral leg exercise on oxidative damage and muscle function were attenuated by consumption of a Montmorency cherry juice concentrate using a crossover experimental design.

CONCLUSIONS:

Montmorency cherry juice consumption improved the recovery of isometric muscle strength after intensive exercise perhaps owing to the attenuation of the oxidative damage induced by the damaging exercise.

Now that’s some juice! This isn’t very surprising, since we all know fruit has a lot of health-promoting compounds. These flavonoids occur in many different fruits, so it is possible that you can get similar benefits from eating or drinking other fruits. For example, peaches and plums are very closely related to cherries, so they may have similar benefits. Blueberries are also loaded with potent flavonoids, though they are not related to cherries.

So grab some fruit or fruit juice after a long strenuous workout, especially the dark colorful ones like cherries or blueberries. Also make sure you get enough protein(I often eat a lot of almonds after workouts) and water. Faster, more complete recovery means being able to exercise on a more consistent basis. Outside of exercise recovery, go easy on sugary fruit juices. They’re okay after exercise because that’s when your muscles need to replenish their glucose.

Do it right, and exercise can be a bowl of cherries.

The Way of the Antioxidant

It always seemed so irresistibly simple. Oxidation = bad, therefore antioxidants = good. Free radicals(any atom or molecule that has a single unpaired electron in an outer shell, making it highly reactive and unstable) have long been seen as the “bad guys” going around our body and causing oxidative damage, by “stealing” electrons from other atoms, leading to aging and disease. This in turn can lead to a chain reaction with the atoms and molecules that had their electrons “stolen” from them becoming free radicals themselves, trying to steal electrons from other atoms.

In comes the police, uh, I mean the antioxidants to put a stop to this mayhem. Antioxidants protect the body’s tissues by donating their own electrons to the free radicals, neutralizing the threat. We actually produce our own antioxidants: glutathione peroxidase, and superoxide dismutase, among others. We also get antioxidants through our diet, such as vitamin C(ascorbic acid), vitamin E(actually a family of chemically similar fat-soluble vitamins), and beta-carotine(and other carotenoids), among so many others. Even the non-vitamin phytochemicals in many plant foods often have antioxidant effects(by definition, vitamins are absolutely essential for the body to function properly, while phytochemicals are not, though at least some of them are beneficial for health).

So taking large amounts of antioxidant supplements would obviously protect the body even more than getting smaller amounts from food, right? Wrong! Indeed, let’s look at the results of a study done on athletes who took antioxidant supplements, people whose muscles are under a great deal of oxidative stress during exercise.

Does antioxidant vitamin supplementation protect against muscle damage?
McGinley C, Shafat A, Donnelly AE.
Source

Department of Physical Education and Sport Sciences, University of Limerick, Limerick, Ireland.

Abstract

The high forces undergone during repetitive eccentric, or lengthening, contractions place skeletal muscle under considerable stress, in particular if unaccustomed. Although muscle is highly adaptive, the responses to stress may not be optimally regulated by the body. Reactive oxygen species (ROS) are one component of the stress response that may contribute to muscle damage after eccentric exercise. Antioxidants may in turn scavenge ROS, thereby preventing or attenuating muscle damage. The antioxidant vitamins C (ascorbic acid) and E (tocopherol) are among the most commonly used sport supplements, and are often taken in large doses by athletes and other sportspersons because of their potential protective effect against muscle damage. This review assesses studies that have investigated the effects of these two antioxidants, alone or in combination, on muscle damage and oxidative stress. Studies have used a variety of supplementation strategies, with variations in dosage, timing and duration of supplementation. Although there is some evidence to show that both antioxidants can reduce indices of oxidative stress, there is little evidence to support a role for vitamin C and/or vitamin E in protecting against muscle damage. Indeed, antioxidant supplementation may actually interfere with the cellular signalling functions of ROS, thereby adversely affecting muscle performance. Furthermore, recent studies have cast doubt on the benign effects of long-term, high-dosage antioxidant supplementation. High doses of vitamin E, in particular, may increase all-cause mortality. Although some equivocation remains in the extant literature regarding the beneficial effects of antioxidant vitamin supplementation on muscle damage, there is little evidence to support such a role. Since the potential for long-term harm does exist, the casual use of high doses of antioxidants by athletes and others should perhaps be curtailed.

Okay, so they don’t prevent oxidative damage to muscles, but can vitamin C at least improve athletic performance?

Effect of vitamin C supplements on physical performance.

Braakhuis AJ.
Source

US Olympic Committee, Sport Performance, Olympic Training Center, Chula Vista, CA 91915, USA. andrea.braakhuis@usoc.org

Abstract

Vitamin C is an essential component of the diet and may reduce the adverse effects of exercise-induced reactive oxygen species, including muscle damage, immune dysfunction, and fatigue. However, reactive oxygen species may mediate beneficial training adaptations that vitamin C attenuates; indeed, from a total of 12 studies, vitamin C in doses >1 g·d(-1) impaired sport performance substantially in four of four studies, possibly by reducing mitochondrial biogenesis, while a further four studies demonstrated impairments that were not statistically significant. Doses of ∼0.2 g·d(-1) of vitamin C consumed through five or more servings of fruit and vegetables may be sufficient to reduce oxidative stress and provide other health benefits without impairing training adaptations.

It appears that supplemental vitamin C impaired performance. The general idea here for why mega-doses of vitamin C and other antioxidant supplements are not protecting tissues or enhancing performance is that not all oxidation reactions are harmful; they are used in many metabolic reactions, for cell communications and are important for the immune system. So if you effectively shut down oxidation with a flood of antioxidants, you may be interfering with some important chemical reactions in your body, and doing more harm than good. Vitamin C isn’t just an antioxidant – it is needed for collagen production and immunity and not getting enough results in a serious deficiency disease called scurvy. Scurvy is very rare in the developed world, and only a small daily dose(60mg) of vitamin C is necessary to prevent it.

The best way to get antioxidants. Source: Wikipedia

Okay, then maybe, just maybe a powerful antioxidant like beta-carotine can protect smokers, who are exposing themselves to a lot of oxidative damage through the act of smoking:

Beta-carotene in multivitamins and the possible risk of lung cancer among smokers versus former smokers: a meta-analysis and evaluation of national brands.

CONCLUSIONS:

High-dose beta-carotene supplementation appears to increase the risk of lung cancer among current smokers. Although beta-carotene was prevalent in multivitamins, high-dose beta-carotene was observed among multivitamin formulas sold to promote visual health.

So far, it doesn’t look like antioxidant supplements are beneficial for anyone’s health. Beta-carotine, in particular, may even increase lung cancer risk in smokers.

This doesn’t mean that antioxidants are themselves bad for you. It just means you are better off getting them from food, where they may interact with other chemicals in the fruits and vegetables they naturally coincide with in a manner that makes them relatively harmless and likely beneficial.

Antioxidants do provide some protection, but that’s not the whole story. It’s long been thought that fruits and vegetables are beneficial largely due to their antioxidant content. This may still be true in part, but the phytochemicals in them may have other ways of protecting our health in ways science is still trying to figure out. Antioxidant content may be a proxy measure of protective phytochemical content, since many if not most phytochemicals tend to have antioxidant effects. Blueberries, with a very high antioxidant content and some possible brain-protecting effects, are a good example of this.

Good health means having a good balance between antioxidants and oxidation reactions, which taking large doses of antioxidant supplements interferes with.