tailored for you
TAKE ADVANTAGE OF OUR DYNAMIC CALCULATOR THAT TAKES THE WORK OUT OF DEVELOPING YOUR PLAN. THE CALCULATOR WILL ALLOW YOU TO USE THE FOLLOWING METRICS.
Exercise intensity
FITNESS LEVEL
SWEAT RATE
HEAT INDEX
OTHER FACTORS
CONTINUE OR SKIP TO CALCULATOR
INTENSITY
TL;DR. DETERMINE YOUR EFFORT LEVEL BASED ON MAX HEART RATE.
The gel calculator table considers light, moderate, and vigorous heart rate zones. Very light and maximal are not included in the table due to these activities primarily being performed in shorter durations. However, significant sweat loss may occur if the duration in these zones is increased. One study known as the talk test identifies light intensity as the ability to talk and sing, moderate intensity as the ability to talk but not sing, and vigorous intensity as not able to talk or sing (Sutton, 22). The talk test can be easily performed without a heart rate monitor.
To identify your estimated max heart in beats per minute (BPM) use your watch data or the Tanaka Formula. Your individual max heart rate may vary, this should be used as a guideline. The following example calculates the estimated maximum heart rate for a 50 year old. Take your own value and continue to determine your estimated BPM in each fitness zone below.
Max Heart Rate = 208 - (0.70 x Age)
Max Heart Rate = 208 – (0.7 x 50 yrs old) = 173 BPM
The American College of Sports Medicine evaluated the intensity of physical activity based on a percentage of your max heart rate. The ACOSM found five zones varying from very light (less than 57% of max heart rate), light (57% - 63% of max heart rate), moderate (64% - 76% of max heart rate), vigorous (77% - 95% of max heart rate), and Maximal (greater than 96% of max heart rate) (American, 23).
The following percentages were chosen within each intensity zone above and calculated below.
Very Light = 173 x 55% = 95 BPM
Light = 173 x 60% = 104 BPM
Moderate = 173 x 72% = 125 BPM
Vigorous = 173 x 90% = 156 BPM
Maximal = 173 x 97% = 168 BPM
By using the Tanaka Formula to determine your max heart rate and the talk test you will be able to identify your exercise intensity level for your activity. You can also use your watch data to find your estimated max heart rate to identify your intensity level.
SOURCES
22. Sutton, B. G. NASM Essentials of Personal Fitness Training. 7th ed. Burlington (MA): Jones & Bartlett Learning; 2021.
23. American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 10th ed. Philadelphia (PA): Lippincott Williams & Wilkins; 2018.
Max Heart Rate
DETERMINE IF YOU WILL BE EXERCISING IN A LIGHT (1), MODERATE (2), OR VIGOROUS (3) INTENSITY ZONE. SKIP TO THE GEL CALCULATOR OR CONTINUE TO DETERMINE YOUR FITNESS LEVEL BELOW.
FITNESS LEVEL
TL;DR. EVALUATE VO2 MAX STANDARDS TO FITNESS LEVEL.
According to the United States Secret Service fitness standards for men and women, push-ups, sit-ups, chin-ups, and a 1.50-mile run are used to identify current fitness levels. The fitness levels are classified from very poor, poor, good, very good, and excellent. For example, a 45-year-old male in excellent shape from 40-49 must be able to do at least 42 push-ups in 1 minute, at least 39 sit-ups in 1 minute, at least 8 chin-ups in one cycle, and under 11:44 in a 1.50-mile run (United States Secret Service, 24). The fitness standards from the US Secret Service are one of many standards across many professions, disciplines, and activities. However, by performing each fitness activity in The US SS test you can determine a starting point for your current fitness.
Another way to evaluate your current fitness level is by calculating your VO2 max (ml/kg/min). According to one article, a high VO2 max (maximum oxygen consumption) correlates to better physical fitness and is associated with a lower risk for cardiovascular disease and increased longevity. The V in VO2 max stands for volume, while O2 stands for oxygen. As such, VO2 max measures how much oxygen your body consumes while exercising. The article states that your VO2 max can be improved by performing vigorous exercise, incorporating high intensity interval training, changing up your workout routine, and losing weight (Warner, 25). In other words, the more oxygen your body can handle during exercise, the longer your body can maintain a higher intensity for longer periods of time.
According to an article from The Cooper Institute, to calculate V02 max (ml/kg/min), an athlete must perform a timed 1.50 mile run on a 400-meter track, under mild weather conditions, and run entirely in lane 1. Record the time it took in minutes. (Farrell, 26).
VO2 MAX = (483 / minutes) + 3.50
Gender, age: Male, 45
Finish time: 10 minutes and 36 seconds (10:36)
Convert to decimal form: 36 seconds / 60 seconds in 1 minute = .60 minutes
Decimal form: 10.60 minutes
Calculate: (483 / 10.60 minutes) + 3.50 = 49 ml/kg/min
As shown by Garmin below, VO2 max is classified into male and female, five categories (poor, fair, good, excellent, superior), and six age ranges (20-29, 30-39, 40-49, 50-59, 60-69, 70-79) (Garmin, 27). This data has been transcribed from a study from The Cooper Institute (Cooper, 28). Please note that Garmin watches calculate VO2 max through metrics such as heart rate, speed, and other personal profile information.
Based on the VO2 max charts from Garmin, for a 45-year-old male to have an excellent VO2 max, he must obtain a score greater than 46.4. From the example above, the 45-year-old male with a score of 49 is classified as having an excellent V02 max.
The gel calculator simplifies fitness levels down to beginner, intermediate, and advanced. To correlate VO2 max to the gel calculator, beginner is considered poor and fair, intermediate is considered good, and advanced is considered excellent and superior.
Calculate your V02 max with the Cooper Test and use the Garmin VO2 max charts to determine your current fitness level. Watch data may also provide you with your VO2 max.
SOURCES
24. “United States Secret Service.” www.secretservice.gov, www.secretservice.gov/careers/technical-law-enforcement/fitness-standards.
25. Warner, Lindsay. “VO2 Max: What Is It and How Can You Improve It? - Harvard Health.” Harvard Health, 8 July 2024, www.health.harvard.edu/staying-healthy/vo2-max-what-is-it-and-how-can-you-improve-it#app.
26. FARRELL, STEPHEN. “50 Years of the Cooper 12-Minute Run | the Cooper Institute.” www.cooperinstitute.org, 8. June 2018, www.cooperinstitute.org/blog/50-years-of-the-cooper-12-minute-run.
27. Garmin. “What’s a Good VO2 Max for Me?” Garmin Blog, 30 Sept. 2020, www.garmin.com/en-US/blog/fitness/whats-a-good-vo2-max-for-me/.
28. Cooper, K.H. (1968). A means of assessing maximal oxygen intake: correlation between field and treadmill testing. JAMA, 203:201-204.Coleman, D. (2015). U.S. military personnel 1954-2014.
VO2 Max CALCULATOR
DETERMINE YOUR FITNESS LEVEL BASED ON YOUR CURRENT VO2 MAX. THIS VALUE CAN BE FOUND FROM YOUR FITNESS WATCH DATA OR BY PERFORMING THE COOPER TEST 1.50 MILE TRACK RUN. RESULTS FROM THE VO2 MAX CALCULATOR WILL PROVIDE YOUR FITNESS CLASS AS BEGINNER (1), INTERMEDIATE (2), OR ADVANCED (0). SKIP TO THE GEL CALCULATOR OR CONTINUE READING TO DETERMINE YOUR ESTIMATED SWEAT LOSS RATE
SWEAT LOSS
TL;DR. SWEAT LOSS RATE WILL VARY FROM PERSON TO PERSON. 1.50 L/HR OR MORE IS HIGH.
Sweat is primarily comprised of 99% water and 1% electrolytes where the sweat loss rate will vary widely depending on factors such as your age group, sex, exercise intensity, fitness level, temperature, and by sport. One study identified the whole body sweat rate in liters per hour by age group and sex. The study found that males 18 and older had a whole body sweat rate of 1.24 +/- 0.62 liters per hour, and females 18 and older had a whole body sweat rate of 0.92 +/- 0.47 liters per hour. The study gathered that the whole body sweating rate for American football players had an estimated loss of 1.51 +/- 0.70 liters per hour, endurance athletes had a loss of 1.28 +/- 0.57 liters per hour, basketball players had a loss of 0.95 +/- 0.42 liters per hour, soccer players had a loss of 0.94 +/- 0.38 liters per hour, and baseball players had a loss of 0.83 +/- 0.34 liters per hour. (Barnes, 10).
According to the aforementioned Coso half-ironman triathlon study, 26 experienced triathletes under the salt group lost on average 4.0 +/- 1.1 liters of sweat with a race time of 307 +/- 32 minutes (5:07:00 +/- 32 minutes). Athletes were allowed to consume as much food as they wanted, which may have contained excessive amounts of electrolytes, carbohydrates and fats across the race which may have led to lower a sweat rate. The average sweat loss was roughly 0.783 liters per hour (4 liters/5.12 hrs.). It is important to mention the average temperature across the race was a comfortable 22.5 degrees Celsius (72.5 degrees Fahrenheit) that has shown to not significantly impact sweat rate. Higher temperatures exceeding 36 degrees Celsius (86 degrees Fahrenheit) and sweat rate will be discussed below. Please see more information below on how temperature is related to sweat rate.
One study evaluated the thermal response to two kinds of t-shirts during exercise and recovery. On two separate test occasions, eight healthy men performed three 20-minute intervals with 5 minutes rest between each interval wearing one t-shirt made of polyester on one test and one t-shirt made of cotton fabric on another test. The study found that the polyester fabric produced a greater sweating efficiency with less sweat retention than cotton fabric, and skin temperature returned to the pre-exercise level faster after the test with polyester (Brazaitis, 29). When considering sweat loss during exercise, polyester has been shown to outperform cotton in breathability and temperature regulation. With singlets, jerseys, and t-shirts made with polyester, clothing is an important factor to consider with sweat loss especially with its ability to wick away moisture, dry more quickly, and keep wearers cooler during exercise. We recommend using fabrics with makeup to be mostly polyester (80%-100%) based on the results from this study.
How do I calculate my sweat loss rate?
According to Garmin, your estimate sweat loss is based on functional threshold power, distance, speed, elevation gain, temperature, heart rate, and some other variables (Garmin, 30). By taking your estimated sweat loss from Garmin and dividing by the activity time you can determine your sweat loss per hour.
Example Garmin Activity: 18-mile run, with a time of 1:58:06, 6:33 min/mile average pace, 968 ft elevation gain, 76 degrees Fahrenheit (24 degrees Celsius), and an average 145 beats per minute heart rate. Garmin calculated for one user an estimated sweat loss of 1,968 ml (1.968 liters). By dividing 1.968 liters by 1.967 hours, the estimated sweat loss is approximately 1 liter per hour. That is equivalent to a loss of 33.8 fluid ounces per hour. Please note there are approximately 33.814 fluid ounces in 1 liter of water. The composition of sweat is approximately 99% water and 1% electrolytes.
Sweat loss formula: Sweat loss (liters) / activity duration (hrs.) = sweat loss (liters/hr.)
Another way to calculate sweat loss is by the amount of weight lost after an activity. Please note there are approximately 16 fluid ounces of water in 1 lbs. of weight.
EXAMPLE CALCULATION
Weigh yourself before the activity = 185 lbs.
Weight yourself after the activity = 181 lbs.
water consumed during the activity = 14 fluid ounces
Exercise duration = 2:08:10 (approximately 2.136 hrs.)
EXAMPLE CALCULATION
Weight loss: 185 – 181 = 4 lbs.
Sweat loss (approximately): 4 lbs. x (16 fluid ounces / 1 lbs.) = 64 fluid ounces
Total fluid loss: 64 fluid ounces sweat lossed + 14 fluid ounces consumed during activity = 78 fluid ounces
Estimated sweat loss: 78 fluid ounces / 2.136 hours = 36.52 fluid ounces per hour (approximate)
36.52 fluid ounces per hour / 33.814 fluid ounces in 1 liter is equivalent to 1.08 liters per hour (approximate)
What is considered low, medium, or high sweat loss?
According to Precision Hydration, sweat loss is categorized as low, moderate, and high. Low is considered less than 1 liter per hour, medium at 1-1.50 liter per hour, and high being over 1.50 liters per hour (Blow, 31).
One study evaluated approximately 500 athletes over a variety of sports and found low to be less than 1 liter per hour, moderate as 1-1.50 liters per hour, and high to be approximately over 2 liters per hour. To note, the study reported that some rates were as high as 3 liters per hour (Baker, 32). From these reports, the gel calculator considers a sweat rate of 1.50 liters per hour or higher to begin to impact performance. Therefore, it is recommended to increase your gel count if your sweat rate is higher. Please note that your sweat rate will vary based on factors such as the heat index, workout intensity, current fitness level, and hilly terrain.
For example, your sweat rate will be higher when the heat index is 95 degrees Fahrenheit (35 degrees Celsius) compared to 45 degrees Fahrenheit (7 degrees Celsius).
SOURCES
10. Barnes, K. A., Anderson, M. L., Stofan, J. R., Dalrymple, K. J., Reimel, A. J., Roberts, T. J., … Baker, L. B. (2019). Normative data for sweating rate, sweat sodium concentration, and sweat sodium loss in athletes: An update and analysis by sport. Journal of Sports Sciences, 37(20), 2356–2366. https://doi.org/10.1080/02640414.2019.1633159.
29. Brazaitis M, Kamandulis S, Skurvydas A, Daniusevičiūtė L. The effect of two kinds of T-shirts on physiological and psychological thermal responses during exercise and recovery. Appl Ergon. 2010 Dec;42(1):46-51. doi: 10.1016/j.apergo.2010.04.001. Epub 2010 Apr 28. PMID: 20427033.
30. “Estimated Sweat Loss in Garmin Connect | Garmin Customer Support.” Garmin.com, 2020, support.garmin.com/en-US/?faq=i3oQUMQucx46gBclVkvoH8. Accessed 27 May 2025.
31. Blow, Andy. “How to Measure Your Sweat Rate.” Www.precisionhydration.com, www.precisionhydration.com/performance-advice/hydration/how-to-measure-your-sweat-rate/.
32. Baker LB. Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability. Sports Med. 2017 Mar;47(Suppl 1):111-128. doi: 10.1007/s40279-017-0691-5. PMID: 28332116; PMCID: PMC5371639.
SWEAT LOSS CALCULATOR
SWEAT LOSS RATE WILL VARY FROM PERSON TO PERSON. DO NOT ASSUME YOUR SWEAT LOSS RATE WILL BE THE SAME DURING ALL ACTIVITIES AND CONDITIONS.
WEIGHT LOSS:
SWEAT LOSS:
TOTAL SWEAT LOSS:
SWEAT LOSS RATE:
SWEAT CLASS:
HEAT INDEX
TL;DR. THE HEAT INDEX IS MORE ACCURATE THAN USING AIR TEMPERATURE ALONE.
One study evaluated the sweat rate of 7 men after 2 hours of exercise at different ambient temperatures. The study found that over 87 degrees Fahrenheit (31 degrees Celsius), the sweat loss began to increase rapidly. This study measured 0.4 liters per hour at 87 degrees Fahrenheit (31 degrees Celsius), 0.9 liters per hour at 90 degrees Fahrenheit (32 degrees Celsius), 1.6 liters per hour at 93 degrees Fahrenheit (34 degrees Celsius), 1.8 liters per hour at 96 degrees Fahrenheit (36 degrees Celsius), and 2.2 liters per hour at 98 degrees Fahrenheit (37 degrees Celsius) (Wyndham, 33).
One study determined that the sweat rate during 60 minutes of cycling at 30 degrees Celsius (86 degrees Fahrenheit) was significantly greater than at 18 degrees Celsius (64 degrees Fahrenheit). At 30 degrees Celsius, the sweat rate was found to be 1.38 +/- .33 liters per hour, and at 18 degrees Celsius, the sweat rate was found to be .632 +/- .31 liters per hour (Green, 34). That is more than a 2x increase in sweat loss from 18 degrees Celsius (64 degrees Fahrenheit) to 30 degrees Celsius (86 degrees Fahrenheit). The results from Green are similar to the aforementioned sweat loss recommendations when approximately 1.50 liters per hour or more of sweat loss is measured.
From these studies, temperatures greater than 30 degrees Celsius (86 degrees Fahrenheit) will increase sweat loss at a faster rate than cooler temperatures. Below we will discuss air temperature compared to relative humidity and air temperature compared to dew point.
When warmer temperatures are combined with higher humidity, even trained athletes begin to feel performance declines. This combination of air temperature and relative temperature is known as the heat index. According to one article from National Oceanic and Atmospheric Administration, the heat index, also known as the apparent temperature, is what the temperature feels like to the human body when relative humidity is combined with the air temperature. This has important considerations for the human body's comfort. When the body gets too hot, it begins to perspire or sweat to cool itself off (US Department of Commerce, NOAA, 35). When relative humidity is considered with air temperature, athletes can benefit from a more accurate representation of how their performance may or may not be impacted.
Please see the simplified chart below courtesy of NOAA to calculate the heat index based off relative humidity for your activity.
Next, dew point compared to relative humidity will be discussed.
According to one article, relative humidity (%) is a percentage of how much moisture is in the air versus how much it can hold and dew point (F,C) is an absolute temperature measurement of how much moisture is in the air (US, 36). In other words, humidity (%) represents water in air as a percentage and dew point (F,C) represents the temperature at which water droplets can form. Please see the dew point scale below courtesy of NOAA.
Please see the link below courtesy of NOAA that provides a calculator for the heat index based off the relative humidity to air temperature and dew point to air temperature. When using the calculator, with an input temperature of 86 degrees Fahrenheit (30 degrees Celsius) and a dew point of 70 degrees Fahrenheit (21 degrees Celsius), a heat index of 91 degrees Fahrenheit (33 degrees Celsius) is estimated. From this calculation, it will feel warmer than the air temperature. With the same input for temperature and 70% relative humidity, the heat index resulted in 95 degrees Fahrenheit (35 degrees Celsius). Again, from this calculation it will feel warmer than the air temperature. From this example, our gel calculator recommends increasing your gel count per hour as your body will be working much harder in these conditions above 86 degrees Fahrenheit (30 degrees Celsius). It is beneficial to evaluate both relative humidity and dew point and use the higher index of the two. This will provide a better representation of how things will feel during your activity. Please see the link below courtesy of NOAA to calculate the heat index for your event.
By calculating the heat index for your activity, you will be able to develop a better nutrition plan with data inputs for air temperature, humidity and dew point.
SOURCES
33. Wyndham, C.H., Williams, C.G., Morrison, J.F. et al. A comparison of multi-stress tests on the sweat rate/rectal temperature relationship. Int. Z. Angew. Physiol. Einschl. Arbeitsphysiol. 23, 305–321 (1967). https://doi.org/10.1007/BF00698040.
34. Green JM, Pritchett RC, Tucker DC, Crews TR, McLester JR. Sweat lactate response during cycling at 30 degrees C and 18 degrees C WBGT. J Sports Sci. 2004 Apr;22(4):321-7. doi: 10.1080/02640410310001641575. PMID: 15161105.
35. US Department of Commerce, NOAA. “What Is the Heat Index?” ww.weather.gov, 2024, www.weather.gov/ama/heatindex.
36. US. “Dew Point Statistics.” Weather.gov, 2024, www.weather.gov/tbw/dewpoint.
Heat Index CALCULATOR
Using Temperature + Relative Humidity
Using Temperature + Dew Point
Elevation gain
TL:DR; WITH MORE CLIMBING, THE HARDER YOU WILL HAVE TO WORK TO KEEP PACE.
The gel calculator considers additional factors that will affect sweat loss. Some factors including altitude, and the number of up hills and down hills may be ignored if an athlete has trained extensively with these conditions. However, if an athlete has trained for such conditions in a cold or moderate climate but is expecting warmer temperatures on race day, it is recommended using more nutrition. All possible scenarios should be considered before an event to ensure the best possible outcome with a course specific nutrition plan.
One article identifies several course profile factors that will affect sweat loss and performance. A marathon course with an overall elevation gain of 1,000 ft (305 m) or more, and (4) four or more up hills and or down hills of 4% or greater (Fleming, 37). A course with a higher elevation gain will require more energy expenditure, fatigues muscles more rapidly, impacts running efficiency, and will overall put more demand on your body. For example, The Sydney Marathon is considered a more difficult course with a total elevation gain of 1,040 ft (317 m) compared to the Chicago Marathon with a lower total elevation gain of 243 ft (74 m). If your course is hilly and more challenging, it is recommended to add more gels into your plan.
SOURCES
37. Fleming, M. (2021, November 9). Data points and hilly marathons. Fitness Protection. https://www.fitnessprotection.com/post/data-points-and-hilly-marathons
HEAT ACCLIMATION
TL:DR; SHORTER ACCLIMATION TIMES IN THE HEAT WILL MAKE YOUR WORKOUT HARDER.
One study found that athletes can acclimate with 10 consecutive days of exercise lasting for 90 minutes at 30 degrees Celsius (86 degrees Fahrenheit) (Périard, 38). After 10 days of heat training most athletes can achieve a lower resting body temperature, increased blood volume, earlier onset of sweating, and a lower resting heart rate. This exposure allows your body to perform more efficiently with the ability to cool down your body and improve thermoregulation under more stressful conditions. Another study found that the customization of this recommendation should be based on the athlete’s training status, recent environmental exposure, available training time (both per day and number of days), tolerance for additional training stress, available equipment, access to hot environments, competition environment, and optimal training phase timing (Racinais, 39).
From one source, heat acclimation was shown to decrease heart rate within 3-7 days, increase plasma volume within 3-6 days, decrease perceived exertion within 5-9 days, and an increased sweat rate from 8-14 days. Additional benefits include reduced salt loss in sweat, reduced skin blood flow, and increased synthesis of heat shock proteins. When heat acclimation is not achieved, the source mentions that sweat volume can increase to almost 3x compared to when athletes have had enough time training in the heat. A loss of heat acclimation begins to reduce significantly after 7 days of no heat exposure and completely removed after 28 days (Powers, 40).
From one study, during the process of training and heat acclimation, sweat rate can increase by 10 to 20 percent or 200 to 300 ml per hour (Marriott, 41). For example, for an athlete with an estimated sweat loss of 1.30 liters per hour and a 20 percent increase is equivalent to 1.56 liters per hour.
SOURCES
38. Périard JD, Racinais S, Sawka MN. Adaptations and mechanisms of human heat acclimation: Applications for competitive athletes and sports. Scand J Med Sci Sports. 2015 Jun;25 Suppl 1:20-38. doi: 10.1111/sms.12408. PMID: 25943654.
39. Racinais S, Alonso JM, Coutts AJ, et al. Consensus recommendations on training and competing in the heat. Scand J Med Sci Sports. 2015;25(Suppl 1):6–19.
40. Powers, Scott K. Howley, Edward T. editors. Exercise and the Environment. Exercise Physiology - Theory and Application to Exercise and Performance. 10th Ed. New York: McGraw-Hill Education. 2018. p269-292.
41. Marriott, Bernadette M. Water Requirements during Exercise in the Heat. Www.ncbi.nlm.nih.gov, National Academies Press (US), 1993, www.ncbi.nlm.nih.gov/books/NBK236237/.
ALTitude
TL:DR; EXERCISING AT HIGHER ELEVATION WILL REDUCE V02 MAX AND IMPACT FITNESS.
One study evaluated the increase in altitude m (ft) alongside the decrease in VO2 max (ml/kg/min). The study performed running tests to exhaustion at the same speed at altitudes of 300 m (984 ft), 800 m (2,625 ft), 1,300 m (4,265 ft), 1,800 m (5,905 ft), 2,300 m (7,546 ft), and 2,800 m (9,186 ft) above sea level using a hypobaric chamber. The study found that VO2 max declined linearly from 66 +/- 1.6 ml/kg/min at 300 m (984 ft) to 55 +/- 1.6 ml/kg/min at 2,800 m (9,186 ft) corresponding to a 6.3% decrease per 1,000 m (3,281 ft) increasing altitude (Wehrlin, 42).
By interpolation, at roughly 1524 m (5,000 ft) VO2 max would approximately decrease from 66 to 61 ml/kg/min.
300 m (984 ft) = 66 ml/kg/min
800 m (2625 ft) = 63.80 ml/kg/min
1300 m (4265 ft) = 61.60 ml/kg/min
1524 m (5000 ft) = 60.61 ml/kg/min
1800 m (5905 ft) = 59.40 ml/kg/min
2300 m (7546 ft) = 57.20 ml/kg/min
2800 m (9186 ft) = 55.00 ml/kg/min
As altitude increases, the study found that VO2 max decreases linearly, resulting in an overall performance decrease at such altitudes due to less oxygen present in the atmosphere. Wehrlin also found that arterial hemoglobin oxygen saturation at test cessation (SpO(2min)) declined from 89.0 +/- 2.9% at 300 m (984 ft) to 76.5 +/- 4.0% at 2,800 m (9186 ft). Normal range is typically between 95% and 100%. Values below 90% are considered abnormal. For example, if you are hiking at 2500 m (8202 ft) it is recommended to increase your gel count due to a likely decrease in VO2 max and less oxygen in your blood resulting in your body working harder than at sea level.
As performance has been shown to decline as elevation increases, the gel calculator recommends increasing your gel count when activities take place above 1524 m (5,000 ft).
SOURCES
42. Wehrlin JP, Hallén J. Linear decrease in .VO2max and performance with increasing altitude in endurance athletes. Eur J Appl Physiol. 2006 Mar;96(4):404-12. doi: 10.1007/s00421-005-0081-9. Epub 2005 Nov 26. PMID: 16311764.
HEADWIND
TL:DR; HIGH WINDS WILL REQUIRE MORE EFFORT TO MAINTAIN PACE.
According to one wind pace adjustment calculator for running, when a headwind is present, your effort will be required to increase to maintain the same pace. For example, for a 195 lbs. runner, with a target pace of 9:00 minutes per mile (5:36 minutes per kilometer), in a city environment, and a 10 mile per hour (16 kilometer per hour) headwind, the runner will need to be moving at approximately 8:39 minutes per mile (5:23 minutes per kilometer) to maintain target pace (Davis, 43). Equivalent to a 4% increase in pace. For example, for a 150 lbs. runner, with a target pace of 5:00 minutes per mile (3:07 minutes per kilometer), in an open environment, and a 15 mile per hour (24 kilometer per hour) headwind, the runner will need to be moving at approximately 4:21 minutes per mile (2:42 minutes per kilometer) to maintain target pace (Davis, 43). Equivalent to a 13% increase in pace. For example, for a 175 lbs. runner, with a target pace of 7:30 minutes per mile (4:40 minutes per kilometer), in a rural/park environment, and a 5 mile per hour (8 kilometer per hour) headwind, the runner will need to be moving at approximately 7:17 minutes per mile (4:32 minutes per kilometer) to maintain target pace (Davis, 43). Equivalent to approximately a 3% increase in pace. From these examples, as the headwind begins to increase above 10 miles per hour (16 kilometers per hour) the pace to maintain the target pace begins to become more demanding. When these conditions exist, it is recommended to increase your gel count as your body will be working harder to maintain your target pace. Please visit the Running Writings calculator site to evaluate your wind conditions.
SOURCES
43. Davis, John J. “Headwind and Tailwind Calculator for Runners.” Running Writings, 2018, apps.runningwritings.com/wind-calculator/#wind-profile-mode. Accessed 29 May 2025.
ADDITIONAL RECOMMENDATIONS
It is recommended to consume a small meal 1-3 hours before an activity with foods that are high in carbohydrates. These foods should be easily digestible with moderate amounts of protein and moderate amounts of fat and fiber. It is imperative to practice with different foods, and with the timing before your activity as everyone’s needs are different. Experimenting during training will prevent nothing new on race day. Your pre-race meal should be small and something that is familiar to your stomach.
It is recommended to achieve clear urine before any physical activity. This can be achieved by drinking enough water days leading up to the activity and 1-3 hours beforehand.
It is recommended to take your first gel based on your goal time to total gels or total distance to total gels. Divide goal time by your total gel count to achieve the approximate time interval to take your first gel and subsequent gel. Divide your total distance by your total gel count to achieve the approximate distance interval to take your first gel and subsequent gel.
It is recommended to experiment with small amounts of caffeine in training before implementing on race day or prolonged training activities. Do not exceed the recommended daily dose. Excessive amounts of caffeine have not been shown to provide any performance benefits.
Gel CALCULATOR
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