How much slower should you run your long run on a 25 degree day? How many extra seconds per lap can you add to your intervals if the humidex hits 30?
Running through the heat is a popular topic of discussion among runners–especially at this time of year. Knowing how to effectively deal with the heat is key to a successful run yet also very difficult to execute.
Kevin Smith is the head coach of Marathon Dynamics, a running club and coaching service that offers training programs and organized workouts for some 150 runners of all abilities in and around the Greater Toronto Area. As a lifelong athlete, experienced coach of over 20 years and a top-level masters athlete, Smith is a trusted source of training and running wisdom. As part of his customized training plans, he also offers his athletes a useful tool when adapting their training for hot and humid conditions.
At what temperature will my running be impacted?
The adjustment tool he offers is designed for anyone hoping to run when the base temperature (or humidex) is above 19 degrees Celsius–so pretty much all summer long. “At around 20 degrees, there is a progressively stronger negative effect on running pace, for any given effort, intensity or speed of running,” says Smith. The tool allows a runner to easily and accurately adjust their target training pace to compensate for adversely hot and humid conditions. The bottom line is that it will provide them with a more realistic training pace. Adjusting these paces will mean that runners will avoid disappointment when their times are slower than the norm.
You can check out the tool as an interactive excel spreadsheet by clicking the link on this page.
How does it work?
By entering the current temperature or humidex (the “feels like” conditions) as well as your originally planned pace in minutes per kilometre or per mile, the tool produces three modified paces: high/aggressive, medium/average and low/conservative. The provided paces mimic a similar training effort. Depending on how well (or how poorly) you cope with heat, the high adjustment is for those who are easily and severely affected by the heat while the low adjustment is for those who deal with heat rather well.
For example, someone wanting to run at an average pace of 5:00/K in 30 degree conditions could adjust their pace by as little as 5 seconds per kilometre (running 5:05/K instead), aim for a moderate adjustment of 11 seconds (running 5:11/K) or slow as much as 21 seconds (running 5:21/K).
This tool can be used for each and every type of run including an easy run, long run or a workout such as a tempo or speedwork.
Use the tool even on “cooler” days with high humidity. Smith also advises reducing the length of your run by 20 to 30 per cent if the temperature or humidex is above 30 degrees. He jokes that “if it’s higher than 40, you should just head to the pool!”
Smith adds that these tools can be used before heading out for runs to proactively adjust target paces or after returning from them by retroactively assessing the weather’s effect. Just be sure to carefully check weather immediately before or after your runs to get a more accurate appraisal of running conditions.