Mark might be the sleeper in this month's challenge after his practice in Paris!


It’s Independence Day weekend and the weather forecast is saying it’s going to be sunny and hot with a chance of sun. Hopefully you’ll take advantage of the terrific weather and get out to the beach, a BBQ, or simply get out of your house and be active. Many of you may find yourselves in the sun for extended periods of time and it’s important to be an educated consumer should you chose to wear sunscreen. A couple of summers ago the NY Times wrote an interesting article on Sun Protection Factor (SPF) and how sunscreen companies may be misleading consumers with inflated SPF ratings.  With SPF ratings hitting 1oo+ we must surely pay the extra cost because it must keep us extra protected, right?  Well if you consider that SPF 100 blocks 99% of UVB rays, shouldn’t SPF 50 only block half that amount?  Well according to the NY TImes piece, SPF 50 only blocks a measly 98% of UVB rays and SPF 30 a puny 96.7%, so is the extra $5-$10 for the higher SPF formula sunscreen really worth it?  I suppose it’s all relative, but when you consider that no matter how high the SPF that none do much to block out UVA rays, the rays commonly associated with premature aging of the skin, it’s even less appealing coughing up the extra dough.  Since I’m sure none of us are in a rush to look like we’re octogenarians, look for sunscreens with UVA-fighting ingredients like an avobenzone that doesn’t degrade in light or Mexoryl SX.

Surely the higher cost associated with higher SPF means we don’t have to reapply the sunscreen as often, right?  Again, this is  not the case either.  A sunscreen’s SPF number is calculated by comparing the time needed for a person to burn unprotected with how long it takes for that person to burn wearing sunscreen. So a person who turns red after 20 minutes of unprotected sun exposure is theoretically protected 15 times longer if they adequately apply SPF 15. Because a lot of sunscreens rub off or don’t stay put, dermatologists advise reapplication every two hours or after swimming or sweating.  To get the SPF advertised, you must use a full shot glass on your body. That’s an ounce, which means a three-ounce tube should last, at most, a few outings.  A common misunderstanding, no doubt perpetuated by sunscreen makers, is that a higher SPF provides more protection when less that the recommended amount is applied.  Unfortunately, this claim has been disproven and the falloff is much steeper, more like the square root of the SPF.  So applying only a half ounce instead of the full ounce of SPF 70 doesn’t give you the protection of SPF 35, but more like SPF 8.4.

Mark Sisson of Mark’s Daily Apple and the Primal Blueprint gave his two cents here, recommending good old fashion physical barriers to the sun like a wide brimmed hat, umbrella, shirts, or pants to protect your skin from the sun’s rays.  Oh, I almost forgot to mention that  a  number of sunscreen lotions have been linked to higher rates of skin cancer.  So before you make your way out to the beach or the backyard BBQ this weekend you have some options to keep your skin protected.  You can simply limit the amount of time your skin is exposed to the sun, you can scope out a shady spot and camp out there, you can wear a hat and clothes that will keep your skin covered, or you can wear sunscreen that has the UVA blocking ingredients mentioned earlier.  If you go the sunsceen route don’t skimp on how much you put on reapplying every few hours so we don’t have a class full of bright red faces come Monday and Tuesday.

WOD 07.02.11

3 Rounds, 1 minute at each station:
Sledge hammer strikes
Tire Flips
Med Ball Burpees
Immediately after the final MB Burpee, perform 100yd hill sprint

2 Responses to “What You Need to Know About SPF”

July 2, 2011 at 3:02 PM

MM – congrats on the nuptials. Looks like you are enjoying the honeymoon. Enjoy!

July 3, 2011 at 2:38 AM


Eating far too “well” – protein is pricey – being able to cook breakfasts at our rented apt. is a good way to go.