There’s much more to come from this, but for now here are my cut and dry thoughts on what exactly you should aim for with a heat-adaptation protocol! If you missed previous posts in this area, please see A Primer On Heat Training and The Science Behind The Sweat! But now let’s get back to basics…
**Special thanks to the lab at James Cook University in Australia for sharing some of their latest research in this area, and a certain anonymous Middle-East based researcher who made sure I had my facts straight!!**
What is the best duration and type of heat acclimation protocol?
This depends on two factors: Firstly, how many sessions are needed to instigate the desired physiological adaptations, and secondly, what logistical constraints exist with relation to the targeted competition? Are you aiming for a weekend long Rugby Sevens tournament, or a 9 hour Ironman Triathlon? Much of the research in this area has investigated the effects on heat acclimation on a single-event performance.
Athletes–and most humans nowadays–are time-poor and therefore must get the most bang for their buck with any training intervention protocol. Preparatory time restrictions in the leadup a a competitive event must be taken into consideration, and hot conditions may only exist for a certain event across a long season, so when considering the best heat acclimation protocols to make use of we must consider both the acute and chronic (residual) effects of such protocols and how you may benefit from them.
Most heat acclimation research with athletes has investigated the impact of either short-term heat acclimation (<7days) or medium term heat acclimation (8-14 days) protocols(Ayogi 1994; Bucheit 2011; Chen 2012; Garrett 2009; Peterson 2010). Both strategies have their merits and can be impactful, leaving the choice of the athlete to be determined based on desired effect and logistical constraints While heart rate and body temperature responses to intense exercise efforts are reported to be improved by both types of protocols, MTHA have been shown to elicit greater plasma volume expansion, though the importance of PV to performance is presently debated(Nielson 1993; Lorenzo 2010; Voltaire 2012).
Therefore we can postulate that STHA is great and instigates plenty of adaptation, but if feasible, MTHA can be even more effective.
To be taken into consideration is what type of athlete you are: are you an elite looking to eke out that last 1% gain from cardiopulmonary adaptations, or a recreational competitor just wanting to make sure you don’t overheat on race day? For athletes preparing for and competing in long duration events such as marathons and triathlons, the body’s ability to deal with heat is more important than for athletes in shorter duration events such as sprinting(Garrett 2011; Harding 2011; Racinais 2012. Therefore this approach must be highly individualized and specific to sport and situation.
As with any human activity, training specifically for that activity delivers the most direct and beneficial results. Therefore, a heat-training protocol which most closely mimics the targeted performance activity is desirable(Taylor 2000). Ergometer (cycle) exercise at an exercise intensity and duration mimicking your target event while either in a heated chamber or outside under the sun is a great start, though keep in mind that humidity should be taken into consideration when mimicking competition-day conditions as closely as possible. Keep in mind that you should push yourself as hard as possible for adaptation while still accounting for maximal recovery; one way to find this balance is to do regular performance tests over the course of an adaptation protocol. For example, after five straight days of 45mins on, 15mins off, 45mins on moderate intensity ergometry to mimic a soccer match in the heat, perform a test or battery of tests mirroring ones performed immediately before beginning the 5-day protocol. Loughborough Intermittent Shuttle Test (LIST) would be an appropriate choice in this circumstance.
Check back in for elaboration on adaptation decay and environmental training for normal-condition improvement in performance! In the meantime, Click Here to Subscribe To Our Mailing List, and Check Out Our Facebook and Twitter Feeds For Banterful Science Sharing!