How to Adjust Speed Workouts to Summer Heat and Humidity

Summer running means hot and humid temperatures, which obviously affect running. The heat increases your heart rate, which means you have to work harder to maintain the same pace. (Read here for why running in the heat is so hard!) For an easy run or long run, you simply scale your pace to keep the effort the same.

 However, speedwork can pose a completely different challenge in summer. Whether you are training for a fall marathon or half marathon or developing speed for summer 5Ks and 10Ks, speedwork may be part of your training plan in the summer, but summer is when these workouts will feel mentally and physically the most challenging. These summer speed workout tips will help you scale your workouts for the heat and humidity so you can continue to train hard without risking heat illness. 

Focus on Effort

When you are running near your VO2max, that often means you simply can’t hit the paces without turning a workout into a race effort – and if a workout becomes a race effort, then it ceases to be a workout. Instead, summer speed workouts are best done when focusing on perceived effort, not pace. Aim for 5K effort instead of 5K pace. The most reliable assessments of effort are your breathing and the talk test. For speedwork, your breathing will be labored so you can only speak a word or two at a time.

Turn Track Workouts in Time-based Fartleks

You can easily adapt a workout to focus on effort rather than pace by scaling the parameters. Track workouts focus on time and distance; even if you are focusing on effort, you may still be tempted to compare your 800m repeats to what you run in cooler weather. Remove all temptation to compare or push the pace with fartlek workouts that utilize time and effort rather than distance and pace. 

If you have 10 x 400m at an 8 minute pace on the schedule, this would translate to 10 x 2 minutes hard. Scale the recovery intervals accordingly as well – 400m recovery would become a 2:30 min recovery. Try these VO2max fartlek intervals for an alternative to popular workouts such as 800m repeats. 

Keep It Short

Shorter intervals are more manageable in the hot months, as you are spending less continuous time working hard. Long repeats such as mile repeats require an increased heart rate for a prolonged period of time, which is more difficult and potential risk in high heat and humidity.

An example of this would be 1-minute fartleks. After a warm-up, run hard for one minute and walk or jog to recover for one minute. Beginners can start at 8-10 repeats; more experienced runners can complete 12-15 repeats. As a benefit, you will improve your leg speed before you start training for your fall race!

Scale the Intensity

Alternatively, you can scale the intensity: rather than doing a workout at 3K-5K pace, scale back to 8K-10K effort (also known as critical velocity). Since your body is already working harder just to say cool in the heat, this adjustment  While these paces won’t render the exact same physiological adaptations, let’s not overthink things: you’ll still do faster running, tax your fast-twitch muscles fibers, and get a good workout.

You may benefit from scaling back your recovery intervals even more. After all, the purpose of recovery intervals is (as the name implies) recovery, not hitting a certain pace. Walk for part of all of the recovery intervals in summer to help your heart rate return to normal and to maintain the purpose of the rest breaks.

Know When to Bail the Workout

Sometimes, it’s not worth pushing through a workout. Speed work in the heat is hard, but it should not be so hard that it leaves you feel weak or completely exhausted. If you are struggling to complete the intervals without stopping, call it a day and run easy instead. Any sign of heat illness, including dizziness, lightheadedness, nausea, or overheating, is a sign to stop your workout.

On extremely hot or humid days, the more prudent decision is often to do an easy run instead or opt for a treadmill workout. 

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What’s the hardest part about summer running for you?
How do you adjust your workouts for summer?