We generally associate exercise with being healthier physically, but its more than just getting fitter. Exercise provides considerable benefit to the human body beyond how low you can get your resting heart rate. Our mental well-being, improved influenza immunisation  and enhanced immunity  all stand to gain by some regular physical activity. Of course, exercise is great for us.
However, can too much be a concern and what happens when we overdo it?
Too much training can be detrimental to someone’s health, particularly in the flu season. Just as exercise can really help our mental health and immunity, the opposite can be true. Exercise can induce an ‘open window’ for opportunistic infectionsvia a transient drop in leukocyte number and/or function . When you run the tank to empty exercising you’re more exposed to a cold or the flu, as you’ve just beat yourself up pretty good. Maybe not for the everyday person, but for elite athletes and those with performance goals load management is a serious topic.
The immune-protective effect of exercise is dependent on the exercise type, duration, frequency and intensity, as well as the training status of the individual. With the current Covid-19 Lockdown, plenty of people are putting down the TV remote (well temporarily at least) and lacing up their runners. This is great and the more people out exercising and taking in the fresh air the better. We do, however, need to be conscious of our limitations and be careful that the exercise we are doing is beneficial and not putting us in a weaker position, where we’re more susceptible to illness.
With people hitting the streets with renewed excitement, the kind that comes from being forced to stay at home, we should be conscious of not overdoing it. If you are determined to keep pounding the pavement (good on you), then you should be thinking about your recovery, beyond stretching.
Here’s how two ingredients can help boost your exercise ability, recovery and immunity following intense exercise - so you can keep pushing those limits.
Foods rich in flavonoids have shown to support immunity under physical stress, like exercise. NZ Blackcurrants are particularly rich in flavonoids, specifically anthocyanins. The extremely high level of anthocyanins found in NZ Blackcurrants promotes a range of benefits complimentary the assumed health benefits of exercise (4). Here are the ways that NZ Blackcurrants can help protect your immunity and support your recovery so you can keep chasing those goals.
Firstly, flavonoid-rich foods have shown to reduce the inflammatory oxidative stress that occurs after exercise. A reduction of oxidative stress was observed in subjects who consumed anthocyanin-rich blackcurrant extract (dose ~ 240mg total anthocyanin) immediately before and after a 30-min row at 80% max. The result is a quicker and more efficient recovery time for athletes. The consumption of blackcurrant also enhanced the suppression of secretion of key cytokines involved in immunity (TNF-α and IL-6) compared to placebo (4). This study was replicated, and the timing of blackcurrant consumption extended to 60 minutes pre-exercise which further ‘hastened the recovery from exercise-induced oxidative stress’ .
Secondly, both the innate (what we are born with) and adaptive (what we develop) immunities are boosted by flavonoid supplementation. Post-exercise, when NZ Blackcurrants had been consumed, the ability of neutrophils to circulate and perform immune responses was maintained. Circulating neutrophils (white blood cells) are the first line of defence against microbial infection. If the function of these circulating neutrophils is maintained then the body’s immune system is best able to attack to immobilise pathogens and viruses that enter our system. In addition to this, the consumption of Blackcurrant extract enhances immune responsiveness to bacterial endotoxin LPS achieved by regular exercise .
In summary, NZ Blackcurrants are great at supporting recovery time and our immune response capability. For people exercising regularly, this should be exciting news, as we all know how deflating it can feel to get on a roll with regular exercise and then get knocked back.
A Blackcurrant picked during harvest, Canterbury, New Zealand
L-theanine, the amino acid found in green tea has a wide range of health effects but is mainly known for its ability to help with stress and anxiety. However, looking at it from an immunity-exercise perspective there are some interesting results showing that regular supplementation with L-theanine could athletic benefits.
A 2019 study on the Polish men’s Olympic rowing team saw athletes supplemented with either L-theanine or a placebo for 6 weeks of training. During this program, subjects were tested with a standard rowing test, the 2000m erg, at the beginning and end of the 6 weeks. Results found that supplementation with 150mg L-theanine for six weeks exerted a beneficial effect on T1/T2 balance and a reduction in IL-10. Specifically, IL-10 levels were reduced in the 24-hour post-exercise period which is when recovery is crucial and the body is more at risk of exposure to pathogens.
What does this mean for the everyday person? Th1 cells cause activation of cell-mediated immunity, and Th2 cells stimulate humoral immunity related to antibody synthesis . Maintaining a balance between these two is important for a wider-reaching immunity. Decreases in IL-10 boosts immunity, thus, seeing the reduction here indicates that those putting their body under extreme physical stress would help maintain immunity with L-theanine supplementation in areas which might have been repressed by exercise.While one study may not be enough to support L-theanine’s immune-boosting properties at this stage, L-theanine also offers benefits to the immune system through other mechanisms; namely improved sleep (6) and reductions in cortisol levels (7).
Sleep is a fundamental requirement for recovery, restoring metabolic homeostasis and regulating key biochemical mechanisms . A bidirectional relationship exists between sleep and immunity where they affect each other both positively, and negatively . Sleep affects our innate and adaptive immune responses, and sleep deprivation can lead to an increase in circulating inflammation markers . Quality sleep is therefore essential for exercise recovery, adaptation and immunity. Without good sleep, the stress we put our bodies under when exercising has a greater chance of affecting us in the short to mid-term. A 2019 study examining the effects of 4-weeks of 200mg L-theanine supplementation in healthy individuals found improvements in sleep quality, and a reduction in disturbances in sleep latency (the amount of time it takes to fall asleep), sleep disturbance, and the use of sleep medication .
Cortisol is a ‘stress’ hormone related to the body’s ‘fight or flight’ response, and at normal levels exerts positive effects on the body. However, elevated levels of cortisol are immunosuppressive and have catabolic effects on muscle , particularly after exhaustive exercise. This further solidifies the idea that our immune systems can be weakened by exhaustive exercise and going beyond our means too regularly. Supplementation of L-theanine has been shown to reduce cortisol levels 50 minutes post a cognitive stressor . L-theanine, therefore, exerts an additional indirect benefit to immunity via improved sleep and reductions in cortisol levels.
Consuming NZ Blackcurrants, due to the high anthocyanin content, helps to not only facilitate the benefits achieved from exercise but actually facilitates immunity post-exercise which may have been weakened. This is done by reducing cytokine production and maintaining neutrophil function so your body can better cope with the introduction of pathogens into its’ system. L-theanine too may help reduce the ‘open window’ following hard exercise by reducing IL-10 and cortisol, as well as enhancing sleep required for recovery. While neither prevent illness, the compounds within these foods/products certainly exert beneficial effects on cells associated with immune response.
If you are looking for a rich source of Blackcurrant and L-theanine - Ārepa's range is packed with anthocyanin-rich freeze-dried New Zeland Blackcurrant, L-theanine and flavonoid-rich New Zealand Pine Bark Extract per serving.
Author: Lillian Morton, MSc, NZ Registered Nutritionist, IOC Sports Nutrition Diploma.
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