Cyclists and caffeine go together like gears and chains – there’s a reason many of us can’t imagine a ride without a pre-ride espresso or a caffeinated gel in our pocket. Does caffeine still deliver its punch when you’re sweating through the dog days of summer or shivering in cooler temperatures?
Whether it’s the promise of an extra boost during a grueling climb or a much-needed energy kick on a long ride, caffeine is a trusted ally for many athletes. In this month’s toolbox article, let’s explore a 2010 study that investigates the impact of ambient temperature on the performance-enhancing effects of caffeine during endurance cycling.
Caffeine & Temperature’s Impact on Performance
Caffeine is widely recognized for its ability to boost endurance performance in various sports, including cycling. Typically, moderate doses of caffeine (6 mg/kg body mass) enhance performance across different exercise types and administration methods. However, the impact of environmental temperature on caffeine’s effectiveness is less clear.
The ideal temperature for optimal endurance performance is suggested to be around 10°C (Galloway & Maughan, 1997). Exercising in heat, such as 33°C, can significantly impair performance by increasing body temperature, which leads to dehydration, altered muscle metabolism, and cardiovascular strain. This hyperthermia can decrease performance due to increased central fatigue and reduced motor activation. Despite caffeine’s general effectiveness in improving endurance, it’s unclear how it interacts with heat stress. Previous studies on similar topics have shown that while caffeine can improve performance in cooler conditions, its benefits in heat are less certain.
Study Overview
This study aimed to clarify whether caffeine could enhance cycling performance in both cool (12°C) and warm (33°C) environments, hypothesizing that caffeine would be more effective in cooler conditions and its benefits might be masked by heat stress. The study recruited eleven male cyclists to participate with an average age of 25, and a respectable relative VO2 max of 58.7 mL/kg/min.
Methods – What did they Do?
The cyclists participated in a double-blind (neither they nor the researchers running the experiment knew whether they were receiving caffeine or a placebo), randomized, cross-over design with four distinct experimental conditions:
- Cool (12°C) with 3 mg/kg dose of caffeine (12-CAF)
- Cool (12°C) with placebo (12-PLA)
- Warm (33°C) with 3 mg/kg dose of caffeine (33-CAF)
- Warm (33°C) with placebo (33-PLA)
Familiarization included a graded exercise test to determine maximal oxygen uptake (VO2max) and practice sessions for the cycling protocol and measurement procedures. Each experimental trial involved 90 minutes of cycling at alternating 15 min efforts at 60 & 71% of VO2max, which could be estimated around 75-85% of FTP.
At the 90-min point of cycling, the cyclists completed a 15-min performance test (PT) at their maximum effort. The total work performed (in kilojoules) was used as the measure of performance. Therefore, riding at a higher average power during the 15 min PT would result in more work performed and was considered a ‘better’ performance.
Throughout the testing, the researchers monitored physiological measures such as heart rate, core body temperature, and sweat rate. Blood samples were collected from the cyclists at multiple time points to assess lactate, glucose, plasma volume changes, and caffeine levels.
Results – What did they find?
Performance Insights: One of the most compelling findings was that caffeine consistently enhanced performance, regardless of the temperature. Cyclists completed more work during their sessions when caffeine was consumed, with a more noticeable boost in performance observed in the cooler environment. This suggests that while cooler temperatures may amplify caffeine’s benefits, the stimulant still provides a significant edge even in warmer conditions!
Table 1. Individual data for the performance tests for each condition. The bottom two lines reflect the most important results – that work performed was significantly higher in cool temperatures and also that more work was done with caffeine compared to the placebo. Table taken from Ganio, et al., 2010.
Cardiovascular and Metabolic Responses: When it comes to cardiovascular and metabolic effects, caffeine didn’t make a noticeable difference. As expected, heart rate and sweat rate increased more in the hot 33°C environment, but caffeine didn’t significantly change these outcomes. Body temperature was also higher in the hot conditions, yet caffeine didn’t affect body temperature or thermal stress.
Figure 2. Heart Rate during the 90 min of moderate exercise & subsequent performance tests. Note that the heart rate was significantly higher in the warm (33ºC) condition compared to the cool (12ºC) condition, regardless of receiving caffeine or placebo. Figure taken from Ganio, et al., 2010.
Hydration and Blood Metrics: Hydration levels were stable across all trials, with no significant differences in urine volume or hydration markers between caffeine and placebo conditions. Interestingly, blood glucose levels were higher when caffeine was consumed, especially in the cooler environment. This suggests that caffeine may have an effect on energy metabolism that is more pronounced in cooler conditions.
Plasma Caffeine Levels: Plasma caffeine concentrations were consistent across the different temperatures, indicating that the actual absorption of caffeine into the bloodstream was unaffected by environmental conditions.
Discussion & Practical Takeaways
For cyclists, this study’s findings offer insights into how caffeine can enhance performance across different conditions. Whether you’re hitting the road in the cool early morning hours or pushing through the midday heat, caffeine appears to deliver consistent benefits. The research showed that caffeine significantly increased the total work done during the performance test, regardless of the ambient temperature. This means that a cup of coffee or a caffeinated gel could help you ride stronger and longer, no matter the temperature outside.
Here are three key takeaways if you’re aiming to optimize your performance this summer:
- Caffeine Dosage: A dose of 3 mg/kg body mass can provide a noticeable performance boost. For example, a 70 kg/154 lb cyclist would benefit from approximately 210 mg of caffeine, which is roughly equivalent to two cups of coffee.
- Temperature Management: This one is pretty intuitive, but whenever possible, cycle in cooler environments, especially for longer or more intense sessions! Cooler temperatures can help maximize the performance benefits of caffeine and reduce heat-related stress.
- Hydration and Cooling: Proper hydration and effective cooling strategies are crucial to mitigating the effects of heat. Even with caffeine’s performance boost, staying hydrated and managing body temperature can make a significant difference during hot rides.
It’s also worth noting that while caffeine improves performance, the benefits might be more pronounced in cooler temperatures. In hot conditions, while caffeine still provides an advantage, the overall heat stress on your body can somewhat diminish these gains. The study highlights that hydration and cardiovascular responses were not affected by caffeine, suggesting that its primary benefit comes from its effects on the central nervous system and energy metabolism. So, if you’re gearing up for a ride in the heat, a moderate dose of caffeine could still be a great addition to your pre-ride routine, helping you push through despite the sweltering summer weather!
Conclusion
Continuing to incorporate a morning coffee into your training regimen does appear to offer a valuable edge, enhancing performance in a variety of conditions. Whether you prefer the chill of early morning rides or enduring the heat of summer, caffeine’s ability to boost endurance and work output remains consistent. Remember to balance caffeine intake with effective hydration and temperature management strategies to make the most of your training and racing efforts. With these insights, you’re better equipped to harness the power of caffeine and tackle any ride with confidence. That’s all for this month – stay safe, ride fast, and I’ll see you next month!
References
Ganio MS, Johnson EC, Klau JF, Anderson JM, Casa DJ, Maresh CM, Volek JS, Armstrong LE. Effect of ambient temperature on caffeine ergogenicity during endurance exercise. Eur J Appl Physiol. 2011 Jun;111(6):1135-46. doi: 10.1007/s00421-010-1734-x. Epub 2010 Dec 1. PMID: 21120518.
Galloway SD, Maughan RJ (1997) Effects of ambient temperature on the capacity to perform prolonged cycle exercise in man. Med Sci Sports Exerc 29:1240–1249
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