All of the studies I've shared (~500 studies) are available on the RESOURCES PAGE.
In this review the authors provide "a new theoretical perspective on how nutrition influences athlete immune health". The authors explain the key points in their review:
A new paradigm for exercise immunology is presented that considers ‘resistance’ (the strength of the immune weaponry) and ‘tolerance’ (the ability to endure microbes and dampen defence activity).
A contemporary view is that immune ‘resistance’ is not suppressed in athletes under heavy training; as such, it is not surprising that nutritional supplements targeted towards improving immune ‘resistance’ show limited benefits to reduce the infection burden in athletes—‘if it ain’t broke, don’t fix it!’
This paradigm of ‘resistance’ and ‘tolerance’ helps to explain why nutritional supplements with tolerogenic effects (e.g. probiotics, vitamin C and vitamin D) are the new targets—tolerogenic supplements may reduce the infection burden in athletes.
PRACTICAL TAKEAWAY - supplementing with vitamin C and D and probiotics during periods of high risk for upper respiratory infection (foreing travel or important competition) could be beneficial.
In this meta-analysis "43 studies with 11 518 athletes were included" that looked at acute / post acute COVID symptoms and were based on observational design. The authors found that"
This broad characterisation of COVID-19 presentations in athletes indicates that ~94% exhibited mild or no acute symptoms.
The available evidence did not confirm a causal relationship between COVID-19 and myocardial involvement.
A small proportion of athletes experienced persistent symptoms while recovering from infection, which were mostly mild in nature, but could affect return-to-play decisions and timing.
PRACTICAL TAKEAWAY - while it is still important to be cautious about return to play after COVID, there is perhaps less to worry about as athletes than we previously thought (I was particularly concerned about the risks of long-terms complications after COVID).
SUPPLEMENT: Acute taurine supplementation enhances thermoregulation and endurance cycling performance in the heat
This study investigated the effects of oral taurine supplementation on cycling time to exhaustion at a fixed-intensity and thermoregulation in the heat. Taurine is an interesting supplement and most commonly associated with Red Bull (one can contains 1000mg). In this study "11 healthy males participated in a time to exhaustion test in the heat (35°C, 40% RH), cycling at the power output associated with ventilatory threshold, 2 h after ingesting: Taurine (50 mg kg−1) or placebo (3 mg kg−1 maltodextrin)".
The findings showed that:
Taurine supplementation increased time to exhaustion by 10%, end sweat rate by 12.7% and decreased B[La] by 16.5%.
Taurine supplementation increased time to exhaustion and local sweating, while decreasing RPE and core temperature in the later stages of exercise, as well as reducing post-exercise B[La].
Based on these findings, a single dose of taurine 2 h prior to training or competition would provide an ergogenic and thermoregulatory effect.
PRACTICAL TAKEAWAY - taurine supplementation could provide a performance benefit, particularly in hot conditions.