11 Factors Increasing an Athlete’s Risk of Cold & Flu


To achieve your athletic potential, you need to train hard and train often. This means walking the fine line between the appropriate amount of training (and life) stress and the positive adaptations it provides and pushing yourself over the edge. The sport science term pushing athletes just past their capacity to improve performance is called functional over-reaching (FOR), it’s what every good strength coach and sport scientist are striving to achieve. Unfortunately, the quest for constant gains means the possibility of stumbling over the line into too much stress (i.e.  non-functional over-reaching), or the abyss of overtraining syndrome, when athletes are tired, rundown and progress stalls for months.(1) Incredibly, 70% of high level athletes have experienced or will experience over-training syndrome (OTS) at some point.(2)

Adding to all this complexity is the reality that increasing training volume is strongly associated with increased risk of upper respiratory tract infections (i.e. cold or flu) and upper respiratory symptoms.(3) Interestingly, even if you're athlete experiences pronounced symptoms of an infection - congestion, scratchy throat, fatigue, etc. - they're at similarly increased risk of diminished performance.(4)

Simply keeping your athlete healthy enough to train is a crucial piece of the high-performance puzzle. If you're healthy, you can train. And if you can train more than the competition, you'll have the best chance of winning (all other things being equal).

To fall victim to an infection, two things must happen; your immune system gets compromised and you're exposed to an infection. Let's take a closer looker at 11 factors that can increase your risk of catching a nasty bug.

1.    Exercise - As I mentioned above, when your training load increases so too does your risk of URTI.(5) This is unavoidable for high-level athletes as they must follow their periodized training plan to achieve their goals and prep for competition. If you're about to enter an intense training period and you feel a scratchy throat, congestion or fatigue setting in, then shifting your focus to your sleep and nutrition strategies is key to supporting immunity.

2.    Mental & Emotional Stress - If you're a person who get stressed out more easily, it actually makes you more susceptible to catching a cold or flu.(6) If you're a type-A personality, experience anxiety-like symptoms or are a general "worrier" than you’re at greater risk of infection as well. Key things to watch out for include fatigue, tension, anger and depression.

3.    Sleep - Lack of sleep is major roadblock to a healthy immune system. If you get less than 7 hours of sleep per night your risk of cold and flu increases 3-fold.(7) Prioritize sleep if you're feeling like you're coming down with something (especially if you're hitting the gym hard).

4.    Personal Hygiene – It’s not very sexy advice, but it plays a massive role in keeping you cold and flu free. Washing your hands regularly – before every meal and after contact with sick people -  and keeping your hands away from your mouth and nose should be your top priority to reduce your risk of infection plummets.(8)

5.    Poor Nutrition - If your diet doesn't have enough calories (i.e. energy) to meet the demands of your training, if you're training at high-intensity with low-carbohydrate availability, if your diet is restricted and low in vitamin D, zinc or iron (just to name a few) then you're likely compromising your immune system.(9) Nutrition is a key player for maintaining a robust immune system and reducing frequency and severity of colds and flu.

6.    Dental Hygiene - You might not think brushing your teeth is a powerful immune booster, but in fact, it's a reliable method for reducing your risk of infection.(10) If you don't keep your teeth clean, bacteria accumulate in your oral mucosa, especially if you’re eating multiple meals and shakes throughout the day. Brush 2-3x a day to reduce your risk.

7.    Sharing Water Bottles - A great motto for life is “Sharing is caring”, just not when comes to athletes and their immunity. Sharing water bottles increases your risk of mononucleosis infection 8-fold!(11) Stick to your own water bottle.. no sharing!

8.    Travel – Plane travel can feel like an immunity Armageddon; waiting to succumb to the onslaught of microbes with nowhere to hide. There is always a handful of passengers  - sneezing, coughing and touching everything in sight – increasing your risk of exposure to infection.(12) Unfortunately, they're putting you at risk and there isn't much you can do about it. Hand sanitizer, a face mask, and if the person next to you is ill, asking to changes seats are probably your best strategies.

9.    Extreme Environments - If you're training at altitude, or in extremely hot and humid environments, your immune system can be impacted. Altitude has been shown to reduce sIgA levels, potentially increasing risk of infection, while hot climates can lead to dehydration and reduced plasma volume, also potentially compromising immunity.(13,14)

10.   Drugs - If your athlete or client is taking medications like corticosteroids for arthritis, asthma or allergies, or if they’re taking immune-suppressive medications for an auto-immune condition they may also be more susceptible to colds and flu.

11.    Vaccination History - If you're team is traveling abroad and you haven't had all the appropriate vaccinations (i.e. hep C, hep B, flu vaccine) then you're increasing your risk of infection.(15) This is not only a performance problem, but a potentially serious health problem.

These 11 factors are some of the most common reasons why your immune system is compromised, and risk of infection increased. Reducing this risk factors, as best as you can, will go a long way to keeping you cold and flu free this winter (or anytime of the year for that matter!) so you can keep training and keep improving.

What about factors that can positively impact your immunity? Here's a short-list of high-impact factors;

1.    Sleep (Listen to Dr. Amy Bender PhD talk sleep strategies in athletes)

2.    Nutrition (Check out 21 Foods To Boost Your Immunity)

3.    Relaxation (Learn how deep-breathing impacts performance)

4.    Periodized Exercise

5.    Holidays  (When was the last time you actually went on holiday? If you can't remember... you need a holiday!) 

Maximize your performance high this winter by minimizing your exposure to colds and flu. Next, add a few fundamental strategies that increase pillars of recovery; sleep, nutrition and mental stress.

Dr. Marc Bubbs ND, MSc(c), CISSN, CSCS


Want to learn 10 evidence-based strategies to reduce illness in athletes? Download my FREE infrographic here! (Coming soon...)

HIIT Sprints & Adults Over-50: The Minimum-Effective Dose

HIIT Sprints & Adults Over-50: The Minimum-Effective Dose

As you get older, it’s more difficult to maintain lean muscle mass. Muscle is not only a crucial factor in physical performance but also a key marker of healthy ageing.(1) After the age of 50 muscular power starts to decline, more rapidly than strength qualities, making it an important factor to focus on during training. Power isn’t just for dynamic sports efforts, your fast-twitch muscles are essential for “catching yourself” as you fall and hip fractures are significant risk factor in older populations. The good news is maintaining muscular power predicts a reduction in future falls, so not only is focusing on power qualities during exercise important for performance, but overall health as well.

Read More

What Is The Minimum-Effective Dose For Hypertrophy?

What Is The Minimum-Effective Dose For Hypertrophy?

When you’re young or have lots of time on your hands, it’s easy to carve out 5-10 hours a week to hit the gym. Getting all your lifts in when you train 5-6 days per week makes achieving your hypertrophy goals quite straight forward. However, as you get older or your time becomes more limited, or if you’re simply looking for the most efficient hypertrophy program possible, the real question is… “how little time can you spend in the gym and still maximize your gains?”

Read More

Strength vs. Size - How Many Reps Are Really Best?

Strength vs. Size - How Many Reps Are Really Best?

Just the other day, a client named Tim came into my office because he was struggling to add lean muscle. He was eating right and training at a CrossFit box 4-5x per week (and getting stronger), but couldn’t seem to pack on the 10 pounds of lean muscle he was looking for. He was stumped. This is a classic case of really having clarity in your goals. Are training to get stronger so that you can perform better in your sport? Or is your primary goal to get bigger and add size to your frame? 

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Are Deep Squats Best for Vertical Jump & Sprints?

The current conventional wisdom among strength coaches seems to be that all clients and athletes should focus on a full range of motion (ROM) to promote superior strength and performance gains. While maintaining full ROM is obviously ideal, depending on the type of athlete you’re working with (and their specific goals), new research is shedding some light on how squat depth translates to performance gains.

A new study compared the effects of squat depth on vertical jump and sprint performance.(1) Twenty-eight college-aged male athletes were divided up and assigned to one of the three groups - full-squat, half squat and quarter squat - then performed a 16-week training protocol to assess the impacts on vertical jump and 40-yard sprint time. Interestingly, the greatest improvements in vertical jump and sprint time were found in the quarter-squat group (see Figure 1.0 and 2.0).

Figure 1.0 – Effect of Squat Depth on Vertical Jump

Figure 2.0 – Effect of Squat Depth on 40-Yard Sprint


Researchers believe that joint-angle specific changes to neuromuscular control may be the root cause of the improvements. Studies have found superior improvements in EMG in trained movements, versus those that are untrained.(2) Of course, the first quarter of the squat most closely resembles the hip and knee flexion ranges seen during jumping or sprinting, which is not surprising for most strength coaches. However, it’s interesting that in highly trained athletes, the load in the full squat seems ineffective for promoting gains in the quarter squat. In short, if you’re not doing quarter squats with your athletes who need to jump higher and run faster, you may be missing out on a piece to promote superior adaptation and performance. (However, it should be noted quarter squats also elicit greater anterior shear force that could predispose athletes to overuse injuries, if they’re not periodized appropriately.[3])

Depending on your athlete’s sport, the findings in this new study may be very impactful. Athletes with poor movement patterns or taller ectomorph-type athletes (i.e. basketball, volleyball, etc.) may benefit greatly from periods of training with quarter squats. If you’re performing deep squats with a basketball player, and using their 1-RM to base their training intensity, the work they perform at the quarter squat level will likely not be sufficient enough to overload the athlete and create positive adaptations. This new perspective of joint-angle overload suggests it’s not enough to simply train at different joint angles, you must overload the specific angle that applies specifically to your athlete’s sport (i.e. sprinting, jumping, etc.).

At the end of the day, quarter squats and full squats are very different; your neuromuscular system assesses and adapts to the stresses of varying squat depths differently. Therefore, it would make sense to incorporate more varied squat depth in your training protocols, just like the use of a variety of exercise to promote the greatest gains in strength and performance.

Dr. Marc Bubbs ND, CISSN, CSCS


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4-Benefits of Ashwagandha For Performance

Withania somnifera, commonly known as ashwagandha, is a powerful herb that’s been used for centuries in Ayurveda - traditional Indian medicine - to build strength, stamina and combat fatigue. Ashwagandha is classified as an adaptagen herb, which helps the body maintain normal physiological function during times of physical or mental stress, builds resistance to future stressors, and promoter superior vitality and energy.1 Popularly known as Indian ginseng, ashwagandha has a vast array of pharmacological benefits; relaxing a stressed nervous system, lowering blood pressure, supporting superior immunity, reducing inflammation, promoting deep sleep, keeping your memory sharp and acts as an antioxidant.(2)

The question is, if you’re training hard in the gym and looking to add lean muscle can the ancestral benefits of ashwagandha help you build more muscle? Or is this yet another example of exaggerated folklore?

A recent study investigated the benefits of ashwagandha supplementation on 57 adult men, aged 18-50, to see if this “wonder herb” really has what it takes to make you stronger. After eight weeks of training, the ashwagandha group showed significantly greater increases in strength, in a one-repetition maximum for bench press and leg-extension compared to the placebo group (see Figure 1).(3) They also experienced greater muscle hypertrophy in the upper-body (not lower-body) as well as seeing superior improvements in body-composition.(3) (Bigger, stronger AND leaner… Not a bad combination!) The benefits didn’t stop there. The group supplementing with ashwagandha also displayed lower levels of muscular damage, suggesting faster recovery after training, as well as greater testosterone levels.(3) Faster recovery means an increased ability to ramp up training frequency, a great recipe for getting bigger and stronger. Furthermore, intense training tends to lower testosterone levels, making this adaptagen herb a great choice during peaking training phases.

Figure 1 -

If you’re a regular gym-goer or advanced trainee, the added support from adaptagen herb ashwagandha may help get stronger, accelerate recovery and keep your anabolic hormone testosterone in balance. Try adding 300mg of ashwagandha, twice daily for 4 to 8 weeks. If you’re a new trainee and hypertrophy is your goal, remember that achieving your ideal daily protein intake and total caloric intake is absolutely crucial to your success and should be your first priority, before adding the “bells and whistles” of supportive herbs.

It can be difficult to fit all your training into a busy schedule when striving for hypertrophy and lean muscle gains. Ashwagandha doesn’t just help you build muscle and recovery more quickly, but offers added benefits of building a better brain and overall health to offset the stressors of busy workdays, constant connectivity and lack of sleep. This ancestral herb does indeed pack a powerful punch.

 Dr. Marc Bubbs ND, CISSN, CSCS


Check out more articles in the TESTOSTERONE SERIES...



1)    Abascal K, Yarnell E. Increasing vitality with adaptogens: multifaceted herbs for treating physical and mental stress. Altern Complement Ther. 2003;9:54–60.

2)    Mishra LC, Singh BB, Dagenais S. Scientific basis for the therapeutic use of Withania somnifera (ashwagandha): a review. Alternative Medicine Review. 2000;5:334–46

3)    Wankhede S. et al.Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial Journal of the International Society of Sports Nutrition (2015) 12:43.


Single-Leg Vs. Back Squats To Improve Strength & Speed?

Back squats have long been considered an essential tool for making athletes bigger, stronger, and faster. By comparison, unilateral exercises like split squats have been relegated to the “assistance” exercise category, the inferior cousin of the almighty squat.

However, the tides might be changing. Recently, a groundbreaking new study in the Journal of Strength & Conditioning demonstrated something that had never been shown before. Strength coaches in the United Kingdom examined the effects of unilateral squat training versus traditional back squats on strength, 40-meter sprint time and change of direction speed. The results were very interesting.

Eighteen rugby players were randomly assigned to two groups - rear-foot elevated split squat (RESS) or classic back squats - for five weeks of lower-body training (twice weekly) to put an old myth to test, are bilateral movements like the back squat truly the “king” of all exercises? The results showed, for the first time, that unilateral training could improve strength, 40-meter sprint time and change of direction to the same degree as back squats. That's right... split squats were JUST AS GOOD AS back squats!

Of course, if your squat movement pattern is very good, there maybe no need to modify your training. However, if you’re an athlete with poor ankle mobility or suffer from low back pain, the confirmation that unilateral exercises like RESS can provide the same benefits as bilateral staples like squats may come as a big relief.

For athletes who need to jump a lot in their sport (i.e. basketball or volleyball players), whose low back are exposed to high torque (i.e. golf and tennis players) or anyone who struggles to effectively load their spine effectively (i.e. ectomorphs) without pain throughout the entire squat movement, this could be a game changer. Unilateral split squats may allow these populations to load their spine more effectively, without pain, thus minimizing risk of injury and achieving a superior training outcomes.

If you feel more pain in your back or neck when squatting, rather than your glutes, hamstrings and quadriceps, a shift to more and heavier unilateral training may be your solution for improved strength and speed.

Dr. Marc Bubbs ND, CSCS

Check out more articles in the "STRENGTH" SERIES...


1) Speirs, Derrick et al. Unilateral vs. Bilateral Squat Training for Strength, Sprints, and Agility in Academy Rugby Players. J. Strength Cond Res. Feb 2016. Vol. 30, Issue 2. p386-92.