Coffee's Performance Enhancing Powers

I remember reading about how drinking coffee can help improve sporting performance in endurance races when I was 17 and competing in track and field races back then. I was not a regular coffee drinker then (nor now). I made myself a cuppa before a track race held at the NUS track (1500m) and ran a personal best!

Back then, I read that the caffeine in coffee was a stimulant and that it enhanced fat burning to give nuscles more energy. Another theory was that caffeine acts in the brain to make  physical exertion feel easier (by blocking receptors that detect adenosine, a molecule that detects fatigue). This also helps in all out bursts of strength, prolonged endurance and cognitive effects like enhanced attention and vigilance.

Fast forward to a recent study that involved cyclists who completed time ridden to exhaustion tests at a predetermined intensity. They could sustain that intensity for around 5 minutes on 9 separate occasions. They were wired up with electrodes and other equipment before and after the rides to assess brain function, circulatory system efficiency and muscle function.

The cyclists did similar rides each time. Either 5 miligrams per kilogram body weight of caffeine was ingested an hour before the ride, or a placebo was taken. In some rides, they stopped the ride prematurely at either 50 percent or 75 percent of the time achieved in the baseline test to assess mid ride neuromuscular function.

In the final ride, the riders were given caffeine but were stopped at the exact time they had given up in the previous placebo trial to get a similar comparison of the effects of riding at a given power for a given duration with or without caffeine.

Here's a summary from the fairly complex analysis by the authors. Caffeine works! The cyclists lasted 14 percent longer (5:55 min) with caffeine compared to the placebo (5:14 min). This is equivalent to a 1 percent gain if the riders did a race or time trial.

Caffeine did help the muscles delay loss of power. Those taking the placebo at the 75 percent mark of the test had lost 40 percent of muscle power compared to less than 35 percent for those who had taken caffeine. At exhaustion those taking the placebo could generate only 60 percent less force than when they were fresh. With caffeine, the loss was 45 percent at the exact same time, pace and power.

The brain (or central nervous system) sent weaker signals to get the muscles to work when the cyclists got more tired when they ingested the placebo. With caffeine, the signals never declined, even when the cyclists reached exhaustion. Their brains were still enthusiastically getting their muscles to contract.

Caffeine also kept oxygen flowing through their arteries, as measured by a pulse oximeter attached to the cyclists' right fingers. There was only a mild decrease at exhaustion compared to a steady decline seen in those who took the placebo. The authors suggested that having more oxygen available may be one of the reasons the muscles kept working better during caffeinated rides.

This study also shows that caffeine also reduced perceived effort - just like what I read when I was 17. The pace you're holding definitely seems easier.

For those of you that are keen to try caffeine, the authors suggest 3 to 6 milligrams of caffeine per kilogram of your body weight taken an hour before your event starts. Higher doses may speed up your heart rate, not what you need during your race. Regular coffee drinkers may get a slight gain if you stop drinking coffee for a week to get that boost.

Reference

Cristina-Souza G, Santos PS, Santos-Mariano AC et al (2022). Caffeine Increases Endurance Performance Via Changes In Neural And Muscular Determinants  Of Performance Fatigability. Med Sci Sports Ex. 54(9): 1591-1603. DOI: 10.1249/MSS.0000000000002944

Definitely No Bull

Energy drinks on offer - you buying?

My previous article on energy drinks like Red Bull was one of the more popular articles the year I wrote about it. Many readers commented that they were not aware how bad energy drinks were. In fact, the World Health Organization issued a statement calling energy drinks a potential danger to public health.

Now it seems that there may be more reasons to avoid energy drinks.

A recently published article suggest that caffeinated energy drinks can also raise blood pressure and alter your heart's electrical circuit.

That is definitely not surprising considering there was a case report showing atrial fibrillation (or abnormal heart rhythm in a 14 and 16 year old boy) and even a case of heart attack in a 19 year old previously after consuming energy drinks

The researchers tested two groups of healthy people between the ages of 18-40.  One group drank energy drinks that can be easily purchased containing 304-320 milligrams of caffeine while the other drank a placebo drink consisting of lime juice, carbonated water and cherry flavoring.

The participants drank 946 ml (or 32 ounces) of either one of those drinks on three separate days while researchers measured their heart's electrical activity and blood pressure. Measurements were taken before they drank, twice within the hour that they drank the beverage and four hours after.

Now, you'll be shocked to read that they group that drank the energy drink showed higher QT intervals up to four hours later. The QT interval is the time it takes the lower chambers of your heart to prepare for a beat. In general, the normal QT interval is below 0.4 to 0.44 seconds. If the interval is too short or long, it can cause arrhythmia. This is a condition where the heart beats abnormally.

Other than the change in QT intervals, those that drank the energy drink had a significant increase in systolic and diastolic blood pressure.

Coffee lovers will be glad to know that the researchers do not think that caffeine is the main culprit for the increase in QT interval. It may be the caffeine in combination with the other ingredients like sugar, high fructose corn syrup, artificial sweeteners and non nutritive stimulants like guarana, ginseng taurine, L-carnitine, inositol, verba mate and D-glucuronoalactone that caused the changes.

The researchers cautioned the elderly, young children and those of you who have underlying long QT intervals, hypertension and taking antibiotics and anti-arrhythmic medication to be careful with consuming energy drinks.

Also, consuming a few cans of the energy drinks can certainly exacerbate those with underlying heart conditions or those taking certain heart medications.

Reference

Shah SA, Szeto AH et al (2019). Impact Of High Volume Energy Drink Consumption On Electrocardiographic And Blood Pressure Parameters: A Randomized Trial. JAHA. 8(11). DOI: 10.1161/JAHA.118.011318.

Now that's a lot of bull you do not want