Impaired exercise tolerance with suppressive thyroid hormone treatment.

Guest post written by Raina Kranz-Kaplan A.C.S.M, CPT.

 First posted SUNDAY, NOVEMBER 26, 2017

Impaired exercise tolerance with suppressive thyroid hormone treatment, to sub-clinical hyperthyroid
Let’s begin with the understanding that this article is being written to help explain what occurs to the body under certain alterations in metabolism, due to thyroidectomy and or RAI. The studies used involved patients with differentiated thyroid cancer and those who may still have their thyroid glands and are sub –clinical hyperthyroid. The state in which we are discussing, is Sub- Clinical Hyperthyroid states and its effects on muscle strength, endurance and cardiovascular endurance and recovery.

Sub-clinical hyperthyroid is clinically described as a Thyroid stimulation hormone (TSH) below the general reference of (0.20-0.30) with Ft4 and Ft3 levels within range. Many patients who have had their thyroid gland surgically removed and gone through RAI treatment for thyroid cancer, are then treated with suppressive therapy to ensure no regrowth of tissue. There are pros and cons to this treatment and latest findings are changing as to whether suppressive treatment to Sub clinical hyperthyroid or complete suppression is needed in all cases of thyroid cancer. This is not the topic of discussion – I just wanted to address the subject briefly as some of you will be having their dose adjusted to accommodate any reclassification of your diagnosis. Please discuss this with your Doctors.

The purpose of this article is to shed light on the fatigue and lack of energy many thyroid cancer survivor’s experience once finishing their initial treatment. We will not be discussing and side effects of RAI and only addressing the physical, emotional and quality of life aspects when it comes to achieving healthier life.

​Let’s talk Optimal Thyroid levels vs Sub clinical hyperthyroid levels.
Optimal thyroid levels are subjective and individual. Each person requires a different level of hormones to feel their best and what it takes to get there is also unique to each patient. That being said, Sub clinical hyperthyroid is not considered optimal thyroid levels. People who present with Sub clinical hyperthyroid levels are watched carefully, tested for Graves’ disease, may have higher blood pressure and resting heart rates. Whereas optimal thyroid levels, are more conducive with a higher perception of quality of life, less physical and less cardiovascular limitation’s.

Exercise and physical response
Training effect/ increased Vo2 (oxygen consumption): is described as a positive correlation to the amount of oxygen one can assimilate and use for muscle contraction at a given intensity. The training effect is relative to an increased amount of work one can perform due to the increased amount of oxygen.

People who have levels considered to be Sub-clinical hyperthyroid either due to suppressive therapy or due to graves’ disease or another thyroid disease experience impaired functional response to exercise – marked by lower values of oxygen consumption and exercise duration. They also experience early onset aerobic threshold (tiring more easily and sooner) and have slower recovery heart rates and blood pressures.

This will make it very difficult for those with Sub clinical hyperthyroid to make progress with exercise and limit their abilities to function at levels that require higher intensities and longer durations. Strength is impaired as well. Sub clinical hyperthyroid levels create lower muscle function and functional capacity of the shoulder and quadriceps and a higher degree of fatigue overall.

The subjects tested for physical impairment ranged from overt hyperthyroidism, subclinical hyperthyroid due to Graves’ disease, toxic goiter and suppressive thyroid hormone treatment due to differentiated thyroid cancer. The studies consistently showed the correlation was due to actual thyroid levels rather than a particular cause or variation of thyroid disease. The same correlation could be made with those who were diagnosed with overt hypothyroidism, still have their thyroid gland, but are over medicated on thyroid hormone replacement. The Sub-clinical hyperthyroid level is the reason for the overall fatigue and low perception of quality of life.

Physical intensity, duration and frequency and its effects on thyroid disease.
It is time to think outside the box and lets delve into what occurs under different scenarios and exercise with various thyroid levels.

Euthyroid describes “normal thyroid levels” if we are speaking of the apparently healthy void of thyroid disease, these levels can be anywhere within the normal reference range. For example; TSH (0.40-4.50). Those with hypothyroid disease due to hashimoto’s or for some reason other than thyroid cancer have had their thyroid removed (not being suppressed to subclinical hyperthyroid) use the term “ optimal’ when trying to achieve a state of well-being. Generally speaking, the aim is to get the TSH closer to 1.0 and somewhere between (0.50-1.5). These levels has not only been shown to be beneficial for hypothyroid patients – they are also beneficial for overall health.

Person’s diagnosed with hypothyroidism also experience a form of exercise intolerance mostly due to having low thyroid function. This interprets in a slower metabolism. Lower resting heart rate, lower body temperature’s, lower blood pressures and low energy levels. Dysfunction at the cellular level resulting in decreased mitochondria and faster fatigue rates during exercise. Many hypothyroid patients do not sweat during exertion. Exercise protocols for hypothyroid patients even medicated to optimal levels need to modify intensity, duration and frequency so that they do not over expend thyroid hormone.

As you can see, both sub clinical hyperthyroid and hypothyroid patients will have some degree of physical impairment due to “non- optimal” thyroid levels. You can actually remove the thyroid gland and see that depending what level a patient is medicated to will result in either a correction in metabolism or an impairment.

Physical activity on thyroid hormone
What occurs to thyroid hormone during exercise is pertinent to how those with thyroid disease may need alter training to increase training effects and benefits. I want to keep this section very simple so, lets focus on intensity of exercise first.

1) Lower intensity aerobic activity 50% -60% of maximal attainable heart rate
2) Moderate intensity aerobic activity 61%-75% of maximal attainable heart rate
3) High intensity aerobic activity 76% -85% of maximal attainable heart rate.

You can apply the above to intensities for circuit training, HITT training, boot camp, weight training. Any of these can be modified for any level, by monitoring heart rate, increasing rest intervals, using lighter or heavier weight and modifying exercises.

Triiodothyronine (bio-active thyroid hormone) also known as T3, is the hormone used for energy and is the gas pedal of thyroid economy. When this level drops generally so does functional output. This is the hormone we need to exercise. The one fact we all need to know is this for all individuals healthy and those with thyroid disease “on thyroid hormone replacement” it does not matter.. Training at a threshold higher than 70% will cause a drop in both total and free T3 levels. The difference is healthy individuals have the ability to actually produce more thyroid hormone as needed and we do not. We are completely dependent upon a given dose and how we use that amount of thyroid hormone needs to be taken into account when we exercise and in our daily lives.

The suggestion for those who are medicated to “Optimal” ranges is to not exert energy over 70% of ones given max heart rate. This is preserve Total T3 and free T3 levels and allow for the body to recover in 12 -24 hours vs 24 hours or more. The next thing to take into account is duration. The amount of time one should exercise with thyroid disease without over-using precious T3 hormone. The studies show that 40 minute – 60 minutes is the allotted time. Frequency the amount days one with thyroid disease should train is between 4-6 days a week.

I am going to break this down.

Novice individual’s 3 days a week 20 minutes /50-60% of max heart rate / for 6 weeks before increasing intensity, duration or frequency
4-5 days a week at 45 minutes – 60 minutes/ 70% of max heart rate
5-6 days a week at 40 minutes /70% of max heart rate
These parameters have shown to reverse mitochondria deficit and increase quality of life.

(Sources) For Hypothyroid
http://www.nel.edu/26-2005_6_pdf/NEL260605A14_Ciloglu.pdf
https://www.ncbi.nlm.nih.gov/pubmed/16380698
https://www.ncbi.nlm.nih.gov/pubmed/9789797
https://www.ncbi.nlm.nih.gov/pubmed/?term=Thyroid+hormone+activation+by+type+2+deiodinase+mediates+exercise+-+induced
https://www.ncbi.nlm.nih.gov/pubmed/16380698
1E7-B5BF-80C

How does this apply to sub- clinical hyperthyroid patients or those being suppressed to sub-clinical hyperthyroid due thyroid cancer? We are dealing with a totally different set of circumstances. The muscle weakness and fatigue is purposely being imposed and for good reason so we have to take that into account. There is several studies that show that exercise for those that fit into this category can benefit immensely and the benefits can be seen and felt after 3 months of consistent movement.

Being slightly over medicated (sub clinical hyperthyroid) you would assume that having more thyroid hormone available would result in more energy than your hypothyroid counterparts it does not .As I mentioned before this state in of itself is causing the impaired physical function.
Sub clinical hyperthyroid and hyperthyroid states cause specific impairment that differs immensely from the impairment that occurs with hypothyroid states. Hyperthyroid status increases RESTING heart rate, RESTING oxygen uptake, exercise heart rate and cardiac output. However maximal oxygen uptake during exercise is decreased despite increased heart rate and increased cardiac output. Fatigue sets in faster due to a 25% increase in lactic acid with in the muscles and maximal oxygen reduction. These effects are associated with a 21-37% decline of the oxidative and glycolytic enzymes in skeletal muscle, specifically a 15% decline in the type IIA muscle fiber. This is due to the accelerated protein catabolism due to the sub clinical hyperthyroid state. The excess amount of thyroid hormone actually leads to a reduction glycogen within muscle tissues.

What does this mean for those being medicated to a subclinical hyperthyroid state?

What are Type IIA muscle fibers?

Muscle fibers break down into two categories
1) Slow twitch (low force/low power/low speed /high endurance)
Exercise training that would utilize these muscle fibers are low intensity and long duration exercises, like walking. Hypothyroid patients benefit from this type of training
2) Fast twitch muscle fibers breakdown a little more into two sub categories. (Type IIA and Type IIB)

Type IIB (high force/high power/high speed/ low endurance) this type of training is typically sprinting. The Type IIA muscle fibers have the most impairment with sub clinical hyperthyroid and hyperthyroid states and the level of intensity falls somewhere in between slow twitch muscle fiber training and fast twitch Type IIB muscle fiber training.

Type IIA, known as fast oxidative are used during sustained power activities and are usually more resistant to fatigue then the Type IIB muscle fibers. In sub clinical hyperthyroid and hyperthyroid states, the Type IIA muscle fibers give out sooner than they should. This results in loss of lean muscle and weakness.

1) Slow twitch muscle fibers work in lower intensity – longer duration training (i.e walking)
2) Fast twitch muscle fibers Type IIA work in moderate intensity – sustained power activities (i.e interval weight training)
3) Fast twitch muscle fibers Type IIB work in high intensity – short duration /high intensity bursts of power at maximal or near maximal effort.( i.e Cross-fit, HITT, Bootcamp)

Patients being medicated to subclinical hyperthyroid and hyperthyroid states would benefit from sustained moderate intensity resistance training. The studies suggest starting with twice a week 20-30 minutes in duration. Using a sustained/steady method movement with little rest in between sets. One way of doing this is choosing 1 exercise for each of the larger muscle groups in the body and performing a set of 12 repetitions for each body part with little rest in between.

Example; Chest, Back, Legs.

Chest press > Lat pull down > kettle bell swing w/ squat. These can be repeated after a short rest, stretching in between or an active rest of 2 minutes at moderate intensity on a piece of cardio equipment or by stepping up and down on a step 4-6 inches.
Generally repeated for a total of 2- 3 cycles.

This can be modified to just doing the resistance exercise and stretching in-between sets and progress gradually to heavier weights, longer workouts and more times per week.
The premise is subclinical hyperthyroid and hyperthyroid patients will not benefit from lower intensity and longer duration training nor will they benefit from higher intensity/power /shorter training programs.

Heart rate was not defined in the findings, so I will suggest a parameter that is more in line of what would be used for those who are on medication to control heart rate and or blood pressure (beta-blockers and other medications like them) It is called “ Perceived Exertion “. Typically you go by how you feel and there is a chart you can use to determine at what level you are working at and what is right for you. Below is a link to the Borg scale of perceived exertion.
Keep in mind less is more and the more consistent you are with your exercise the more you can do over time.
https://www.cdc.gov/physicalactivity/basics/measuring/exertion.htm

(Sources) For subclinical hyperthyroid and hyperthyroid.
https://www.ncbi.nlm.nih.gov/pubmed/22471990
http://www.nrcresearchpress.com/doi/10.1139/y2012-044#.Whs1r0qnHIU
https://www.ncbi.nlm.nih.gov/pubmed/1752962
https://www.ncbi.nlm.nih.gov/pubmed/7840280
https://www.ncbi.nlm.nih.gov/pubmed/8392830

[Resistance training improves muscle function and body composition in patients with hyperthyroidism.]
https://www.ncbi.nlm.nih.gov/pubmed/16876559
http://www.archives-pmr.org/article/S0003-9993(06)00399-6/fulltext

Abstract

OBJECTIVE:
To evaluate the effect of resistance training on skeletal muscle performance and body composition in patients with medically treated hyperthyroidism.

DESIGN:
Nonrandomized controlled trial.

SETTING:
Large public tertiary hospital.

PARTICIPANTS:
Sixteen sedentary patients with recent clinical diagnosis and laboratory confirmation of hyperthyroidism (7 men, 9 women; age, 38+/-11 y; weight, 58.4+/-2.6 kg; height, 1.6+/-0.3m) were assigned to the control group (medical therapy; n=9) or training group (medical therapy associated with resistance training; n=7). An age- and sex-matched healthy group served as controls (3 men, 5 women; age, 40+/-3 y; weight, 68.4+/-4.3 kg; height, 1.6+/-0.3m).

INTERVENTION:
Resistance training twice a week for 16 weeks.

MAIN OUTCOME MEASURES:
Peak muscular strength (by dynamometry and 1 repetition maximum method) and endurance (30% of peak force) for 7 movements and anthropometric measurements.

RESULTS:
The hyperthyroid patients as a group had lower baseline overall strength values when compared with healthy subjects (200.3+/-16.0 kg vs 274.9+/-21.8 kg, respectively; P=.006). Overall absolute increases in strength (49 kg vs 91 kg, P<.05) and endurance (78.5x10(2)kg/s vs 176.9x10(2)kg/s, P<.05) were higher in the training group compared with the control group. Body weight increased in both groups, but the sum of muscular circumference increased only in the training group (training group, 92.6+/-3.3 cm vs 97.1+/-3.8 cm; control group, 94.6+/-2.2 cm vs 94.4+/-2.1cm; P<.05), with no change in the sum of skinfolds.

​CONCLUSIONS:
Resistance training accelerates the recovery of skeletal muscle function and promotes weight gain based on muscle mass improvement in patients with medically treated hyperthyroidism.

About Raina: ​Thyroid Advocate contributor at Thyroid Nation,  Owner/Personal Trainer at Conscious Fitness of Hollywood Florida