Physiology Friday #91: Do Fitter People Drink More? + The Best Time of Day to Exercise -- According to Science
This week's newsletter covers studies investigating the relationship between fitness and alcohol consumption, plus data on how circadian rhythms affect our exercise performance.
Due to the upcoming holiday, I am releasing this week’s newsletter a few days early. I hope that you can find this content useful and enjoyable amidst the festivities and time with friends and family.
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With that being said, let’s get into today’s newsletter, where I’ll briefly summarize two neat studies I came across this week.
Do fitter people drink more?
While exercise is a good habit that typically clusters with other good habits including a healthy diet and adequate sleep, there is also a paradox in that engaging in high levels of physical activity seems to lend itself to a “licensing effect” — where one believes that they deserve or have earned themselves a reward for their hard effort. This reward can often take the form of an alcoholic beverage. Sometimes, nothing complements a sweaty workout like a cold beer (or two). One could presume that high levels of exercise may be associated with higher levels of alcohol consumption — whether due to this licensing effect or some other social phenomenon.
This question was investigated in a recent (cleverly-named study) titled: Fit and Tipsy? The Interrelationship between Cardiorespiratory Fitness and Alcohol Consumption and Dependence.
Researchers analyzed data from over 38,000 participants who were enrolled in a large study out of Houston, Texas called the Cooper Center Longitudinal Study. These individuals all completed a maximal treadmill (VO2 max) test to determine aerobic fitness. Data were also available for participants’ drinking habits — how much and how often they consumed alcohol during a typical week as well as their symptoms of alcohol dependence.
Women and men who were more fit tended to consume more alcohol than their less-fit peers.
Specifically, women who were categorized as “moderately” or “high” fitness were 1.58 and 2.14 times more likely to be moderate to heavy drinkers compared to “low” fitness women.
Men categorized as “moderate” or “high” fitness were 1.42 and 1.63 times more likely to be moderate to heavy drinkers compared to “low” fitness men. Interestingly, men in the study who were more fit were less likely to report alcohol dependence, a finding not observed in women.
These results somewhat support what I’ve seen and experienced myself. On a more personal note, I know that I tend to consume a bit more alcohol during periods of heavy training, precisely due to the aforementioned “licensing effect,” but also because a beer can be a refreshing way to relax (rehydrate?) after a long hard run. There’s sometimes nothing better.
None of this is to say that a heavy exercise routine warrants a higher alcohol consumption, as any alcohol likely poses a risk to health. We also don’t know whether the more “fit” individuals in this study actually participated in greater amounts of exercise. Whatever the reason — whether it be celebratory or a form of self-reward — drinking and exercise seem to have one unique and perhaps surprising relationship.
What time of day to exercise for peak performance
We all have a preferred time of day when we like to workout. Some of us are early risers who start (and perhaps finish) before the sun comes up. Others may enjoy hitting the gym after work to de-stress and work up a late-afternoon sweat.
Preference plays a huge role in exercise adherence, enjoyment, and performance. Working out when you feel the most motivated and alert is important.
However, there is no arguing that our biology, and therefore our physiology, is somewhat out of our control. Strong evidence exists to suggest that several parameters of performance are under the control of our circadian rhythms; meaning they fluctuate throughout the 24-hour day and have distinct peaks (high points) and troughs (low points).
To put it in simple terms — depending on the time of day, we may have more endurance and greater strength. Practically, knowing when these peaks occur could help one to design a more effective workout and competition schedule.
A recent systematic review and meta-analysis investigated these diurnal (day/night) variations in performance. Specifically, researchers scoured the literature for studies on how endurance performance, power output, hand grip strength, and jump height all varied throughout the day.
For all four of the performance variables analyzed, performance was significantly higher in the afternoon/evening compared to the morning. We even have specific clock times when peak performance occurs for each variable.
- Endurance: 3:06 pm +/- 5.5 hours
- Power output (cycling): 4:18 pm +/- 2.5 hours
- Handgrip strength: 5:00 pm +/- 3.5 hours
- Jump height: 3:12 pm +/- 2.25 hours
When we choose to workout isn’t always under our control — lifestyle, work, and other obligations dictate when the day’s workout happens (or doesn’t).
However, if peak training output is the goal and one is free to plan their workout routine, it seems logical to plan for a mid- to late-afternoon time slot. This would theoretically allow a greater workload, enhanced training adaptations, and in the long-term, more fitness gains.
If you are going for a personal record/personal best — plan your attempt for later on in the day, when your chances of success are drastically increased.
And if biology is at odds with your personal preferences, then just get your workout in whenever you are able. Exercise is good, no matter the time of day.
Thanks for reading. See you next Friday.
Shuval K, Leonard D, Chartier KG, et al. Fit and tipsy? The interrelationship between cardiorespiratory fitness and alcohol consumption and dependence. Medicine & Science in Sports & Exercise. 2022;54(1):113-119.
Knaier R, Qian J, Roth R, et al. Diurnal variation in maximum endurance and maximum strength performance: a systematic review and meta-analysis. Medicine & Science in Sports & Exercise. 2022;54(1):169-180.