Table 1.

Examples of Incremental Activity Intensity, Duration, Equipment, and Work-to-Rest Ratio Modifications for Exercise in the Heat^a

Level	Intensity	Duration	Equipment	Work-to-Rest Ratio (Total Rest, min/h)
1	No restriction	No restriction	No restriction	5 : 1 (10)
2	Allow self-pacing	Maximum of 2-h activity	Remove protective equipment during breaks	4 : 1–3 : 1 (12–15)
3	Relatively low-intensity exercise	Maximum of 2-h activity with increased rest breaks	No protective equipment during conditioning or practice	2 : 1–1 : 1 (20–30)
4	Walk through, no conditioning	Maximum of 1-h activity	No protective equipment	Work < rest (continuous heat exposure should not exceed 30 min)
5	Cancel activity	Cancel activity	NA	Cancel activity

Abbreviation: NA, not applicable.

^aModified from Hosokawa et al.⁶⁷