The FastDay Forum

[carorees]

I just came across this paper: http://www.hormones.gr/752/article/article.html
The study examines the effects of interval training versus steady exercise on thyroid hormone status in athletes. The findings are that exercise creates a temporary state of hypothyroidism which is more prolonged following interval training.

The two exercise regimes used in the study were 45 minutes of continuous treadmill running at 60-65% of VO2max (steady exercise) or a series of intense 90-second anaerobic interval (~100-110% VO2max) runs on a treadmill, alternating with 90-second recovery intervals of easy running (~40% VO2max)lasting 45 minutes in total. These were compared with a control resting period. Thyroid hormones were assayed before and 12 hours after the exercise session.

The authors' conclusions:

In conclusion, our findings indicate that intensive interval exercise results in a suppressed peripheral conversion of T4 to T3, as compared to a comparable amount of steady-state, sub-maximal endurance exercise. This occurrence implies that a longer recovery period is necessary for thyroid hormonal levels to return to normal following intensive interval exercise to allow for any transient hypothyroidal state that may develop to abate. Since low thyroid hormone levels are potential biomarkers for over-reaching – overtraining, the present findings could have implications for the implementation of training regimens relative to the rest and recovery needs of the athlete.

I wonder whether some folk who are asking about poor/no weight loss despite doing a lot of exercise might be over-training?

Other studies on thyroid function and exercise:
http://www.ncbi.nlm.nih.gov/pubmed?link ... id=6798059
http://www.ncbi.nlm.nih.gov/pubmed/6748921
http://www.ncbi.nlm.nih.gov/pubmed/4046839
http://www.ncbi.nlm.nih.gov/pubmed/3101339

So damned if we do, and damned if we don't perhaps?

[carorees]

I guess it's another one for the maxim "moderation in all things"

We can't win, can we?

I developed a hypothyroid condition about two years ago, aound the time I was doing some HEAVY running training - i was running 6 days a week, and trained for and ran two half marathons. I have ALWAYS suspected that this was what brought on all my thyroid issues, and complete inability to lose weight in spite of all the running and a faultless diet.

I'm interested in this subject. I'm 52 and had a total throidectomy 7 years ago. I take a low dose of thyroxine every day (75mcg). I exercise every day, lots of cycling and gym interval training - and still find it very hard to move weight. After visiting a dietician to discuss my diet and lack of weight loss, I was told i had the healthist diet of any client she'd ever had - so, how to explain the lack of results for my hard work?? The good news is that since starting the 5:2 fast diet, three weeks in so far, I have actually lost 2 kilos, this is amazing for me - so thinking that the fasting process is actually working. Is anyone else taking thyroxine and do you have any tips? Thanks.

I have hypothyroidism too (Hashimoto's disease) and I started boxing (really hard core, Thai boxing, in a ring and all) last year. I suffered from extreme exhaustion and kept putting on weight (admittedly, quite a lot of new muscle). The above study could explain it very well. In the end I got so tired I started hurting myself all the time and had to stop boxing. I was devastated, as I loved it. Now I dance and that never seems to tire me, despite copious amounts of sweat and sore feet!

Ooh!

Does this mean we don't have to exercise?!

[carorees]

Ha ha! No, it just means you shouldn't do excessive exercise, especially the high intensity stuff! The only people who might like to consider reducing slightly are those who are spending hours each day exercising hard.

If you look in the "not losing weight" section you'll see a few posts from people saying something like: "I'm fasting twice a week, eating 1500 cals on feed days and every day I run 10 miles and spend an hour in the gym but I'm not losing weight". Those are the people who might just be over training.

So, back you go to the treadmill basketcase!

Ha ha! No, it just means you shouldn't do excessive exercise, especially the high intensity stuff! The only people who might like to consider reducing slightly are those who are spending hours each day exercising hard.

So, back you go to the treadmill basketcase!

Thought so...

Serious question on the back of the facetious comment.

What does this mean in terms of blood count? Would it give the appearance of a rise in the levels?

(As you can tell, I'm not scientifically minded! )