With the current COVID-19 pandemic creating global disruption, uncertainty and with many countries enforcing society lockdowns, it is making physical activity and exercise more onerous. However, one of the few exceptions to the lockdown rules is exercise, so lets examine the evidence on exercise and immune function.

It is well known that regular bouts of exercise lasting up to 45 minutes of moderate to vigorous exercise is beneficial for immune defence, particularly in older adults and those with chronic diseases. This type of exercise is beneficial for the normal functioning of the immune system and is likely to help lower the risk of respiratory infections/illnesses. However, there is debate within the scientific community whether acute bouts of vigorous intensity exercise leads to a period of immune suppression post exercise.

There has been a long held concept in exercise immunology developed in the 1980s and 1990s called the “open window” hypothesis which proposes a J curve relationship between exercise intensity and infection risk. Which is supported by the belief that athletes who engage in high volume endurance training experience a greater incidence of Upper Respiratory Tract Infections (URTI) compared to those who are less active. Until recently this concept has remained relatively unchallenged.

The “open window” hypothesis suggests that following a prolonged (>1.5hr) and vigorous acute bout of exercise or following chronic intense training (>1.5hr on most days) there is an “open window” which results in an increased risk of opportunistic infections such as URTI’s. The three principles underpinning this concept are:

1). Infection risk increases after prolonged vigorous aerobic exercise

2). Acute bouts of vigorous exercise can lead to temporary reductions in salivary immunoglobulins resulting in higher risk of opportunistic infections

3). A period of post exercise reduction in peripheral blood immune cells resulting in a period of immune suppression.

J Curve – relationship between the risk of infection and level of exercise intensity

Recently though there has been emerging evidence suggesting this concept may be outdated. There is evidence, albeit small that indicates international athletes suffer from less URTI than national athletes. This raises the likelihood that infection susceptibility is more likely multifactorial including genetics, sleep, stress, nutrition, travel, circadian misalignment and increased exposure risks due to close proximity of crowds rather than being directly attributed to acute or chronic bouts of vigorous training. This also indicates that international athletes are potentially better supported, have access to better education helping them to improve their life-style behaviours over national athletes resulting in lower risks of infection.

Secondary to this, evidence supports the opposite of the three principles upholding the “open window” concept. With no changes seen in mucosal immunity which has previously been flagged as an indication of immune suppression. The reduction in blood immune cells (primarily lymphocytes) 1 to 2 hours post exercise reflects a transient and time dependent redistribution of immune cells to peripheral tissues resulting in a heighten state of immune surveillance and regulation leading to enhanced antibacterial and antiviral immunity, not suppression of the immune system.

Further research is needed to confirm or refute the “open window” concept however, it currently appears that the infection risk post vigorous exercise is more likely to be associated with a multitude of other factors rather than purely post exercise immune suppression. So for athletes and non-athletes the message remain the same during COVID-19, regular moderate to vigorous exercise is beneficial to enhance immune function to reduce the risk of bacterial and viral infections including URTI’s. And remember that good hygiene practices (washing hands regularly, not touching your face), physical distancing, getting good quality sleep, reducing stress levels and eating healthy wholefoods are the keys keeping your immune system in peak condition.

Find out more information on COVID-19 here.

The Game Changers, a movie promoting the benefits of a plant-based diet on athlete performance has been gaining a lot of traction. With big sports stars involved like Lewis Hamilton, Novak Djokovic, Arnold Schwarzenegger, Jackie Chan and backed by Hollywood heavy weight director and producer James Cameron one can see why. However, for the uninitiated majority of those involved with this production including the chief science advisor are supporters of plant-based diets, leading to a somewhat biased slant. Therefore, the question needs to be asked “what does the research really say about plant-based diets and athletic performance”.

“love to put Viagra out of business, just by spreading the word on plant-based eating.”

James Cameron – The Independent 25/04/2018

Diets for athletic performance are extremely individualised and are geared towards the specific demands of the athlete and sport the individual competes in. In a very simplistic manner, it requires a balance of protein, carbohydrates and fats to aid with the development of lean muscle mass, energy production and recovery matched against energy expenditure or calories burned throughout the day.

Gluten Free Diets

Athletes are always looking to find that extra edge over their competitors and diet is one area that can be utilized to good effect however, all that glitters may not actually be gold. A few years ago with the explosion of gluten and wheat intolerances and celiac disease a few athletes decided to go gluten free and claimed it was responsible for improving their athletic performance, even though they hadn’t been diagnosed as celiac. Interestingly though these claims aren’t currently supported by the research, with a study in 2015 that took 13 competitive endurance cyclists with no history of celiac disease and compared their time trial performance while on a short term gluten containing diet and on a gluten free diet. The study showed athletic performance didn’t improve for the athletes on a gluten free diet with no history of celiac disease. Given, this study had a small sample size of 13 athletes and was conducted over a short time period (7-day diets) it is however currently the only study comparing gluten free and gluten containing diets on athletic performance in non-celiacs.

Ketogenic Diets

Ketogenic diets have been another diet trend amongst athletes, especially in the world of sports like CrossFit. Ketogenic diets are low in carbohydrates and high in fats, which at first glance seems counterproductive to athletic performance when carbohydrates are an athlete’s main source of energy. In the non athletic population Ketogenic diets or low carbohydrate diets have been shown to be beneficial with weight-loss and reductions in the risk of diabetes. One could argue that reducing body mass might be an important goal in endurance and weight based sports however, the current limited literature looking at ketogenic diets and athletic performance does not support the use of ketogenic diets for athletic performance. Although ketogenic diets do not negatively impact performance, they may lead to unwanted decreases in lean body mass or a drop off in skeletal muscle hypertrophy.

Plant-Based Diets

As it is becoming quickly evident the current literature investigating diet and athletic performance is sparse and generally low in quality. This trend continues when comparing plant-based diets versus omnivore (animal and plant) diets and athletic performance, especially in the elite athletic population which is the premise of The Game Changers documentary. A search of PubMed found only one review paper which systematically reviewed the current literature comparing vegetarian and omnivore diets with physical performance. The paper included 8 studies, 7 randomised controlled trials and 1 cross-sectional study and found there were no differences in athletic performance between a vegetarian-based diet and omnivore diet.

“As someone who follows a plant-based diet, I believe we need a healthier high street option that tastes amazing but also offers something exciting to those who want to be meat-free every now and again.”

Lewis Hamilton on his Neat Burger company – The Sun 29/08/2019

With such limited and low-quality evidence currently available comparing diets and athletic performance, it is extremely important in this commercial and marketing driven age that we step back and ask questions to understand where the truth lies, rather than letting a documentary “inform” us. Plant-based diets and reducing animal meat intake has been associated with health benefits, with a large section of the research on plant-based diets focusing on its potential risk reduction in chronic preventable diseases such as cardiovascular disease. At present there is limited research available analysing its effects on athletic performance with no known larger scale multi-arm studies comparing a variety of diets on athletic performance. Currently the evidence does not show a positive association between a plant-based diet and athletic performance compared to other animal meat with plant based diets.

Diets for athletes, especially elite athletes are extremely individualised and what works for one athlete might not necessarily work for another. Whatever diet is chosen, plant-based or omnivore it should be driven by a nutritionist, dietitian or health professional with sports nutrition training and be grounded in the best evidence available.  

Achilles Tendinopathies

Achilles tendon pain is a prevalent condition that is an extremely frustrating and challenging condition to treat for both patient and practitioner. Fortunately there is a strong and ever growing body of evidence that supports the use of heavy tendon load exercises in the treatment of tendinopathies, especially achilles tendinopathies (AT).

In September I published an article in the Chiropractic Australia, COCA News magazine examining AT and what the evidence currently tells us.

Taming Achilles Tendinopathies

Supplements Are Big Business!

Sports nutrition supplements, more formally known as nutritional erogogenic aids are part of a supplement industry that is currently booming, with sales in Australia skyrocketing to $1billion dollars per year. It is not hard to miss manufacturers bold advertising campaigns, their lists of powders, pills and liquids for pre workout right through to post workout and recovery, all there to help you “train harder” and achieve “mass gains”. If you do miss the advertising, you cannot miss the plethora of blogs and websites dedicated to sharing what the “best” performance supplements to take are.

Do Supplements Really Work?

But do these advertised supplements actually work? The simple answer is well summed up by Professor Ron Maughan who said “if it works, it is probably banned (by WADA). If it is not banned, it probably doesn’t work.” However, there are some exceptions that we will get to. For elite athletes subjected to drug testing, ergogenic supplements can be a challenging area. Studies show high rates of contamination among supplements with one study ranging from 12-58%, predominantly for prohormones and stimulants. There are also everyday health considerations for non athletes, do you want to be ingesting a supplement containing a banned substances?

How To Protect Yourself From Banned Supplements

Thankfully there are some tools out there to help athletes and individuals to navigate through the challenging world of ergogenic supplements. There are fantastic sites like informed-choice who independently test batches of supplements to determine if they contain banned substances. The Australian Institute of Sport (AIS) also have a sports supplement framework which is based around the best available evidence to determine the safety, efficacy and legality of different supplements.

Which Supplements Work And Which Are Banned?

Using the AIS framework it becomes clear which supplements have strong evidence to support their use and which don’t. Grade A supplements backed by strong evidence which aren’t banned include:

  • Caffeine
  • Beta-alanine
  • Bicarbonate
  • Beetroot juice (nitrates)
  • Creatine
  • Glycerol

Grade B supplements, those containing emerging evidence or deserve further research include:

  • Carnitine
  • Fish oil
  • Curcumin
  • Branched Chain Amino Acids (BCAA)
  • Tyrosine
  • Vitamin C and E

Grade D supplements, those that are on the banned WADA list include:

  • DMAA (stimulant)
  • DMBA (stimulant)
  • DHEA (prohormone/hormone booster)
  • Maca root powder (prohormone/hormone booster)
  • “Peptides”

Don’t be drawn in by the bold advertising nor the websites and forums. Have a thorough understanding of the risks and benefits of any supplements being considered. Consult an appropriately trained health professional to see if you actually need to be taking any supplements at all, it maybe a change in diet and training is all that is required. There are ergogenic supplements out there that have good evidence to support there ability to enhance performance in endurance, sprint and power sports. However, there are also a great deal of supplements out there that have no evidence to support there use and may well even include banned substances, so make sure you know what you are putting into your body.

High intensity interval training (HIIT) is hugely popular in the exercise world at the moment, leading to an explosion of “HIIT” style group classes and work outs. Unfortunately though, many of these classes and work outs are not actually HIIT programs as used in the research literature. Therefore the results individuals achieve won’t be inline with the results HIIT research supports. Is this a bad thing? Probably not, if it means people are exercising this far outweighs the difference in health outcomes comparing HIIT and vigorously intensive classes.

An example of a true HIIT program which was used in a research study using HIIT to treat patients with heart failure involved 4, 30 second sprints at 90% of max HR on an inclined treadmill with 4 minute rest intervals, building up to 6 sprints.