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Table of Contents

• Thyroid disease and the endurance athlete, what th …

• Meet the intern-Cosette Rhoads

• James Elvery-CEO of Race Ranger

• Episode takeaways:

  • References used for the MMB

Thyroid disease and the endurance athlete, what the gland does and how derangements in function impact the ability to perform

The thyroid gland lies within the neck and for most people it is out of sight, out of mind. But for a little more than 1 in 20 of the population, (increasing in frequency with advancing age) dysfunction of this gland can lead to important clinical effects. The thyroid may be thought of as the throttle for our metabolic engine and exerts its influence by virtue of thyroid hormone. Too little and everything ….slows….way down. Too much and everything moves way too fast. In either situation the impact on the heart and on the cells in the periphery is important and can result in significant impairment in the ability to do endurance exercise. Normally, the thyroid gland is under very precise control via a feedback loop wherein the amount of thyroid hormone controls how much thyroid stimulation is being given off by the hypothalamus within the brain. As more hormone is released, the stimulus decreases and vice versa. Autoimmune disease can throw this balance off. In one instance, Hashimoto’s thyroiditis, antibodies are created that attack the gland and render it inactive, unable to synthesize or release hormone and hypothyroidism results. In another, antibodies bind to the gland and cause it to release hormone in a way that is unchecked. This results in hyperthyroidism and is called Grave’s disease.

Fortunately, medications exist to control the effects of both hypo and hyperthyroidism and those who are affected need to be tightly controlled to ensure that they do not have ill effects. Coach Juliet and I went in to a lot of detail about what the thyroid gland does and how athletes can manage their chronic condition and still succeed with weight management and performance.

Meet the intern-Cosette Rhoads

My name is Cosette Rhoads, and I’m one of the TriDoc podcast researchers! I graduated with my B.A. in Biology from Grinnell College in 2023, and since then I’ve been working on neuroscience research as a fellow at the NIH in Washington, D.C. I love digging into the literature for the TriDoc podcasts, especially the topics that help me know what to use in my own training! In college, I competed on the swim team as well as on the club water polo team, and since graduating, I’ve been enjoying getting into running. Otherwise, I spend my time reading, hiking, being with friends, and exploring all the great museums, events, and food in the D.C. area!

James Elvery-CEO of Race Ranger

James according to James:James has been in and around triathlon his whole life since watching his father race as a toddler in the 80’s. As an active kid he swam competitively, but growing up all he wanted to be was a top triathlete. James won a few NZ schools titles at high school in the late 90’s, and started racing overseas for NZ at the age of 15. At 18 he finished 5th at the 2002 Junior World Champs in Mexico, and soon graduated to the senior ITU circuit. For 8 years he based himself in Europe, racing on the German Bundesliga and French Grand Prix circuits. His best result was 15th at the ITU World Series race in Madrid in 2011.

On retiring from racing in 2012 James worked at Specialized Bicycles in NZ during the day in sales and marketing roles. As a non-technical founder, RaceRanger was a passion project for evenings & /weekends. James resigned from Specialized in late 2023, and is now working fulltime on RaceRanger.

In James’s role as CEO he leads and project manages product development and all aspects of building the business.

James lives with his wife Tatiana and 3 children aged 8, 6, and 4 in Wanaka, New Zealand.

In a world where triathletes are often left wondering if their competition is playing fair, Race Ranger swoops in like a superhero with a tech-savvy cape. James Elvery returns to the Tridoc Podcast to shed light on how this nifty gadget not only tracks drafting but also enhances safety for every participant. No more chaotic bike packs where someone’s drafting off you like they’re in a Tour de France highlights reel! The system uses a combination of lights and technology to enforce rules, and it’s finally making its debut among age-groupers. We get into all the juicy details about how it works, including the fascinating tech behind the scenes that tracks your distance from the rider in front of you. The conversation flows from the challenges of scaling up for larger races to the proactive measures taken to ensure that athletes are not only competing but are safe while doing so.

Episode takeaways:

• The podcast discusses the importance of understanding thyroid issues in athletes, highlighting how thyroid function can significantly impact training and performance.

• There's a strong emphasis on the need for athletes to communicate with their medical teams about thyroid issues and other health concerns to optimize performance.

• The introduction of Race Ranger technology is transforming triathlons by improving drafting enforcement among pros, making races fairer and more enjoyable.

• Safety is a big deal—Race Ranger not only tracks drafting but can also alert referees about accidents or athletes going off course.

• Post-race data analysis is going to be a game changer! Athletes will have access to detailed stats about their performance, including who they passed and their speeds.

• Scaling up Race Ranger technology for larger age group races is a work in progress, with plans to simplify the setup process and enhance athlete tracking to ensure safety and compliance.

References used for the MMB

McAllister, R. M., Delp, M. D., & Laughlin, M. H. (1995). Thyroid status and exercise tolerance. Cardiovascular and metabolic considerations. Sports medicine (Auckland, N.Z.), 20(3), 189–198. https://doi.org/10.2165/00007256-199520030-00005

Summary:

Review paper from 2012 that notes that hypo- and hyper-thyroidism both cause exercise intolerance (as measured by reduced VO2max and endurance in animal models), but do so via different mechanisms. For hypothyroidism, the authors posit that exercise intolerance is a result of reduced cardiovascular support (reduced oxygen delivery due to reduced skeletal muscle blood flow causes an increase in usage of intramuscular oxygen). For hyperthyroidism, the etiology of exercise intolerance is likely that muscle glycogen is over-utilized instead of cardiovascular changes.

Kahaly, G. J., Kampmann, C., & Mohr-Kahaly, S. (2002). Cardiovascular hemodynamics and exercise tolerance in thyroid disease. Thyroid : official journal of the American Thyroid Association, 12(6), 473–481. https://doi.org/10.1089/105072502760143845

Summary:

Review paper from 2004 that talks specifically about hyperthyroidism’s effect on cardiac function. This paper again notes the measurable decrease in cardiovascular exercise test performance in animal models of hyperthyroidism. In hyperthyroidism, an increased metabolic state and increased oxygen consumption result in an increase in cardiac output at rest, which may affect regulatory mechanisms that change cardiac output as a response to exercise. The effects of hyperthyroidism on cardiac function are more pronounced in older populations (human).

Klasson, C. L., Sadhir, S., & Pontzer, H. (2022). Daily physical activity is negatively associated with thyroid hormone levels, inflammation, and immune system markers among men and women in the NHANES dataset. PloS one, 17(7), e0270221. https://doi.org/10.1371/journal.pone.0270221

Cross-sectional observational study, ran GLM with body mass index, age, gender, activity and TSH as factors showed that active adults had a lower levels of T4 and reduced slope of the TSH:T4 relationship. Introduction of this paper shows mixed findings in reference to the question of whether exercise reduces thyroid hormone T4 or whether populations of individuals that exercise more frequently have less thyroid hormone T4 than populations that do not. 

“One framework for understanding the impact of physical activity on other physiological systems is the Constrained Energy Expenditure hypothesis proposed by Pontzer, which posits that increased physical activity leads to reductions in the activity of other (i.e., non-musculoskeletal) systems [15–18]. This suppression could be evident in global (i.e., whole-body) mediators of metabolic activity, such as thyroid hormone. Results from studies examining the effects of chronic exercise on resting levels of thyroid hormones have been mixed. In animal models, sustained exercise results in lower levels of T4, T3, and TSH [19–21]. Krogh et al. found sled dogs had significantly decreased levels of all three thyroid hormones after four months of vigorous physical activity [21]. In humans, Pakarinen et al. [22] reported a reduction in resting T4 levels in response to 24 weeks of intense weight lifting, but these levels returned to pre-training values when training ceased. One study of female collegiate long distance runners reported lower levels of T4, T3, and TSH than non-athletes but no differences in measurements taken before versus after competition season [23]. Female rowers in a 20-week training program showed mixed responses in TSH, T3, and T4 [24]. However, we note that human studies to date examining thyroid responses to exercise have general lasted less than 6 months. Measures of morning testosterone levels in male endurance runners suggest endocrine adjustment to physical activity may occur over longer time periods, perhaps several years [25].”

Navarro-Navajas, A., Cruz, J. D., Ariza-Ordoñez, N., Giral, H., Palmezano, J., Bolívar-Mejía, A., Santana, Q., Fernandez, R., Durango, L., Saldarriaga, C., Mateus, J. C., Garnica, D., Sarta-García, J. G., Lizcano, F., & Tapias, C. A. (2022). Cardiac manifestations in hyperthyroidism. Reviews in cardiovascular medicine, 23(4), 136. https://doi.org/10.31083/j.rcm2304136

Summary

Lots of information on cardiovascular health and hyperthyroidism. Hyperthyroidism causes increased risk for 1) heart failure, 2) arrhythmias (primarily sinus tachycardia and AF), 3) secondary hypertension, and 4) pulmonary hypertension and pulmonary embolism. 

Kimura, H., Kawagoe, Y., Kaneko, N., Fessler, H. E., & Hosoda, S. (1996). Low efficiency of oxygen utilization during exercise in hyperthyroidism. Chest, 110(5), 1264–1270. https://doi.org/10.1378/chest.110.5.1264

Summary 

Experimental study looked at hyperthyroid patients’ (n=12, 7 male) exercise capacity before and after treatment that reduced serum T3. Reduction of serum T3 via treatment was positively correlated with PRP (PRP = pressure rate product, an index of cardiac work rate correlated with myocardial oxygen consumption). All participants had no arrhythmias prior to experiment. 

Kahaly, G., Hellermann, J., Mohr-Kahaly, S., & Treese, N. (1996). Impaired cardiopulmonary exercise capacity in patients with hyperthyroidism. Chest, 109(1), 57–61. https://doi.org/10.1378/chest.109.1.57

Summary 

Experimental study looked at female Grave’s hyperthyroid patients’ (n=12) and healthy controls without heart disease (n=18) exercise testing results. For patients, results were assessed before and after methimazole treatment that reduced thyroid hormone levels until participants were in euthyroidism for 1 year. 

Metrics that improved given treatment: work rate, heart rate increase given exercise, oxygen uptake at the anaerobic threshold in percentage of the oxygen uptake at maximum WR (VO2 AT of VO2 MAX, %), tidal volume, respiratory rate, heart rate to oxygen uptake ratio, minute ventilation to oxygen uptake ratio, and minute ventilation to carbon dioxide uptake ratio. 

All metrics that are significantly different between patients and controls initially improve with antithyroid medication.

Duñabeitia, I., González-Devesa, D., Varela-Martínez, S., Diz-Gómez, J. C., & Ayán-Pérez, C. (2023). Effect of physical exercise in people with hypothyroidism: systematic review and meta-analysis. Scandinavian journal of clinical and laboratory investigation, 83(8), 523–532. https://doi.org/10.1080/00365513.2023.2286651

Summary

Systemic meta-analysis of the effect of exercise on hypothyroidism. Across 10 studies (n=120), exercise showed a non-significant trend towards reducing TSH levels. Even in comparison with control groups added into the model, results were non-significant. Other variables that were analyzed in the meta-analysis showed that 1) exercise significantly reduced body fat, 2) exercise significantly reduced triglyceride levels and increased high-density lipoprotein levels, and 3) exercise significantly increased fitness measured by VO2max. Non-significant trends showed reductions in response time to exercise, systolic blood pressure, and RPE. Heart rate and kinetic and diastolic blood pressure were unchanged given exercise.

Ahmad, A. M., Serry, Z. H., Abd Elghaffar, H. A., Ghazi, H. A., & El Gayar, S. L. (2023). Effects of aerobic, resistance, and combined training on thyroid function and quality of life in hypothyroidism. A randomized controlled trial. Complementary therapies in clinical practice, 53, 101795. https://doi.org/10.1016/j.ctcp.2023.101795

Experimental study looked at the effect of exercise on female hypothyroid patients’ (n=60) TSH, T4, lipid profile, Vo2 max, and quality of life. Participants were divided into 4 groups evenly: aerobic training, resistance training, combined AT/RT, and a control group. All 3 exercise groups showed significant betterment across all metrics compared to the control group. There were some between-group differences in the exercise groups: 

“The combined AT/RT group showed more significant improvements in TSH and the mental component summary score of the SF-12 compared to the AT and RT groups (p < 0.05). The AT group showed the most significant improvement in estimated VO2 max, followed by the combined AT/RT and then the RT group. Non-significant differences were found between exercise groups in T4, blood lipids, and the physical component summary score of the SF-12 (p > 0.05).”

Lankhaar, J. A. C., Kemler, E., Hofstetter, H., Collard, D. C. M., Zelissen, P. M. J., Stubbe, J. H., & Backx, F. J. G. (2021). Physical activity, sports participation and exercise-related constraints in adult women with primary hypothyroidism treated with thyroid hormone replacement therapy. Journal of sports sciences, 39(21), 2493–2502. https://doi.org/10.1080/02640414.2021.1940696

Cross-sectional observational study, looked at sports participation and physical activity in a population of women with primary hypothyroidism that was being treated (n= 1724) and age-matched controls (n=1802). Patients were less likely to engage in moderate intensity physical activity but were more likely to participate in sports. ⅔ of patients reported that hypothyroidism limited their performance (which was most pronounced in patients with autoimmune thyroiditis).