Wednesday, May 28, 2014

When is it too hot AND humid to ride?

I've spent a lot of time thinking about (and a little time researching) how heat and humidity factor into conditioning for horses.  I think there is a lot more research about people, and I even found a couple of websites that provide pretty specific guidelines for different types of livestock.  However, despite reading something at some point that said a new method for calculating a heat stress index for horses had been developed as a result of (or maybe prior to?) the Atlanta Olympic Games in 1996, I've been unable to locate a specific formula other than Temperature + Humidity (and sometimes - Wind Speed) = Heat Stress Index.  I should note that the Heat Stress Index is different than what is sometimes called the Heat Index (or occasionally referred to as the Steadman Index).  The Heat Index is based on a formula used by NOAA and is designed to tell you what it "feels like" outside.  I think the Heat Stress Index might be more valuable, partly because it is easier to calculate, but I still wish I could find a formula specifically for horses.

Because I live in Virginia, I have the joy of experiencing all the fun of winter plus southern summers.  Southern summers are characterized by fairly high temperatures (85-100 plus) combined with fairly high humidity (50-100 percent).  While we don't get the extreme heat experienced by some western states, I think the humidity levels add an extra layer of information that needs to be considered when conditioning for endurance.  It particularly matters to me because I have a big, black, warmblood/draft type horse who probably doesn't cool as efficiently as a smaller, lighter breed.

Last year, I used this rule (which is based on assorted guidelines I've seen in general heat stress articles, but a little different than the standard - I'll explain why in a bit).  If the Heat Stress Index (Temperature + Humidity) was:

  • Under 130, no worries (Unless the actual temperature was over 90 degrees, then I would take it a little easy).
  • Between 130 and 160, take it easy on anything particularly strenuous.
  • Between 160 and 180, do mostly walking work and keep dressage schooling to short bursts with frequent breaks.
  • Over 180, don't ride.
I should explain that most articles I've seen use 150 as a breaking point between OK and be careful, rather than the 160 I used.  The reason I adjusted my breakdown is because I noticed that it was really hard to find a time during the day when the Heat Stress Index wasn't over 150, particularly during July and August.  To my way of thinking, there has to be some level of acclimatization for a horse that lives outside or in a non-air-conditioned barn.  So, I decided that because Nimo was essentially constantly living in the 150 or above range, he wasn't going to be as bothered by that level of heat and humidity as a horse for whom that level was unusual.  I never experienced any problems with conditioning Nimo in the 150 range (or actually at any point - his heat/humidity tolerance is higher than mine).  However, I did start to notice problems with me once things got over 160.  If I didn't manage myself pretty carefully, I would feel pretty bad after rides. 

In terms of using electrolytes for Nimo, I didn't use any commercial products last year because my thinking was that it just didn't seem necessary for rides less than 25 miles.  I did add about a half tablespoon of salt to every feeding and to all post-ride mashes (in addition to making sure a salt block was available in the stall and paddock).  But, I'm thinking that I'd like to expand that protocol a bit this year.  The reason is because I've found that for me, drinking Gatorade (even though it really is not that great of a product due to the high sugar content) makes the difference between feeling fine after a hot ride and feeling like I want to die.  And, if it makes that much difference to me, maybe it would make that much difference to my horse.

So, I'm planning to do a little experimenting on my conditioning rides this year.  Because I feel best if I drink Gatorade before, during, and after a ride, I'm going to try doing a minimum of a pre- and post-ride mash with electrolytes in it for Nimo.  If I can get a during-the-ride mash in for rides longer than 2 hours and where there are opportunities to drink, I'd like to do that too.  I don't think I'll start out using a competition level of electrolytes for Nimo.  Instead, I'll probably use maybe half as much to start and go from there.

So, to answer my title question...For me, it is too hot to ride if the temperature is over 95, regardless of humidity level.  I just don't tolerate heat well, and I don't see any reason to torture myself even if Nimo doesn't mind.  I also consider it too hot and humid to ride if the Temperature plus Humidity is over 180 because I think the effort needed to ensure proper hydration and cooling just isn't worth it.


  1. I'm with you. My horses fair far better than I do. I suffered some sort of heat-related illness two summers ago and haven't been the same since. My goal for myself this year (started yesterday to get myself in the habit) is to drink a minimum of 90 oz. of water/day. If I can make a habit now before the weather gets nasty, maybe I can manage to not suffer so hard this year. The overwhelming nausea and dizzyness that hits me suddenly when its too late to do anything aside from sitting idly in a cool room isn't something I need to hit me during a ride! Eep!

    Did you look into any of Mel's posts from her and Farley's heat conditioning for Tevis last year? I'm thinking about trying some of that for myself and Q/Griffin this year. 10-20 minute workouts each day at the peak heat. Lunging works for the horse, even. I think I may do lunging + bike riding. I don't need to be responsible for a large animal if I get struck down for some reason with a bout of dizzyness. Haha.

  2. Yes, I've seen Mel's posts on heat conditioning and I've concluded that she is far more dedicated than I am:) I am planning to do some rides in mid- to late-afternoon to try to acclimate both of us to working in the heat. But I'm not planning to do any actual endurance rides until September, so hopefully my heat conditioning doesn't need to be too intensive this year.