Football linemen and heat stroke: why exertion matters

A WBGT reading describes the conditions on a practice field: air temperature, humidity, sun and wind. It says nothing about what the players are doing, and for football linemen, a national task force says, that is most of the story.

In June 2026 a task force of the National Federation of State High School Associations (NFHS) Sports Medicine Advisory Committee published a one-page paper, "Preventing Exertional Heat Stroke (EHS) in High School Football Linemen." Its last recommendation opens with the whole idea: "EHS is predominantly exertional rather than environmental."

What the task force and the review behind it found

The paper cites a 2025 review in the journal Sports Health (both are linked below). Together they report that:

• In the review's count of high school and college football heat stroke deaths from 1998 to 2018, every one happened in conditioning, not in a game, most often in the first week of practice.
• 97% of the players who died were linemen, and 37% of the deaths were tied to exercise used as punishment.
• Linemen build heat faster and lose it more slowly than other players: working hard, a big, muscular body can make more heat than its surface can shed, and more body fat holds it in, even in linemen who are fit and acclimatized.

The review says severe heat and humidity are clearly tied to how often heat stroke happens. But the weather in those deaths was, on average, not extreme: the review reports a mean high of 90.8 °F (32.7 °C) and a mean wet-bulb globe temperature of 76.7 °F (24.8 °C), which on our own general scale is Moderate, the third of six bands. The review reads that as support for limiting how hard players work.

The task force lists uniform reduction (lighter gear), WBGT scales, acclimatization periods and hydration as guidelines that are still important but have not been enough to stop the deaths, because none of them takes account of how hard a player is working, or of which players are most at risk.

Why the same WBGT is a different load

WBGT sums up what the surroundings do to a body, the heat they add and how easily they let it escape, not how much heat the body is making. That depends on effort. A player walking through a practice makes a modest amount; a lineman in a sprint-heavy conditioning drill makes far more, in a larger body that sheds it more slowly. Same field, same reading, very different loads.

Occupational heat standards build this in, with lower WBGT limits for heavier work. A school's heat table usually sets one group of practice changes for the whole team at a given reading. The task force's answer is to manage how hard linemen work as well.

What the task force recommends

In summary (the paper's own wording is worth reading in full):

• Make training and conditioning position-specific, building intensity and duration up gradually, above all in the first week of any new conditioning or preseason program.
• Keep linemen out of some preseason fitness testing, such as mile runs and serial sprints, for the first few weeks.
• Never use exertion drills as punishment.
• Take a struggling athlete out of training at once, for evaluation and treatment.
• Rehearse the emergency action plan for heat stroke, with its rapid cooling protocol.
• Keep following the established acclimatization, hydration and WBGT guidelines, with the practice changes they call for.

Where exertion fits in the app

Our WBGT is a modeled estimate for planning, not an on-site reading, and like any WBGT it describes the conditions, not the player. The optional "Adjust for your situation" card adds the person. It asks for your consent before showing any settings; skip it and the general reading works as before.

Its "Exertion" setting has three choices. "Resting" adds nothing, "Light exertion" adds a personal heat load of 1.5 °C (2.7 °F) and "Heavy exertion" adds 3.0 °C (5.4 °F). The sum is read on the same scale and shown as "Your risk," alongside the general reading, which stays on the card unchanged. At a WBGT of 25 °C (77 °F), Moderate, "Heavy exertion" makes "Your risk" read High, with the reason "while exerting heavily," and the Activity guidance card flags the stricter band too. Early in preseason, "Not heat-adapted" under "Used to this heat?" adds another 1.5 °C (2.7 °F); the acclimatization article explains why. The settings only ever raise the read.

These loads are our own planning estimates, smaller than the roughly 4 to 6 °C by which occupational heat limits fall from rest to heavy work (the methodology has the details), so for an all-out conditioning drill they are, if anything, on the low side. They are not the task force's, and they know nothing about a player's size, position or fitness. What they offer a coach or athletic trainer is a planning view, and a limited one. At the review's average of 24.8 °C, just under that example, "Heavy exertion" alone still reads Moderate; add "Not heat-adapted" and it reads High. Neither says how hard a given drill should be. They do not replace the athletic trainer, the association's rules or an on-site WBGT reading.

Where the rules live

The rules your school follows come from its state association, and some associations have posted this NFHS paper alongside their own heat policy. Read your association's document (find your state in school sports heat policies by state, or search a place in our athletics view to see its state's policy and a link to it, where we could source one), follow your school's emergency action plan, and take any question about a particular athlete to your athletic trainer.

Sources

• NFHS Sports Medicine Advisory Committee Task Force, "Preventing Exertional Heat Stroke (EHS) in High School Football Linemen," June 2026. Posted by the NFHS.
• Anderson SA, et al., "Preventing Exertional Heat Stroke in Football: Time for a Paradigm Shift," Sports Health. 2025;17(3):484-490. doi:10.1177/19417381241260045

General guidance, not medical advice. Our WBGT and the personal read are modeled estimates for planning, not an on-site reading or an assessment of any athlete.