Reddit mentions of ACSM's Guidelines for Exercise Testing and Prescription

Edit preface: I started writing this post thinking I was on /r/science, and didn't realize this was /r/ELI5. I'm gonna finish the post the way I started it, but I'll write a TL;DR when I'm done.

Hi there, exercise physiologist here. It's a Sunday, meaning no OP testing, meaning I'm bored as hell and have access to the hospital library. I'll take a stab at it.

Let me set something straight about performance supplementation: for most of the substances below, there is little evidence suggesting that exogenous performance aids impart any chronic increase in exercise performance. That is, the positive effects of supplementation generally last only as long as the substances are being metabolized [1]. The only exceptions in the list below are the hormonal agents hGH and testosterone.

The two major supplements you're mentioned, exogenous creatine and erythropoietin, are used to increase performance through different mechanisms.

Creatine monohydrate significantly improves the anaerobic (non-oxygen-utilizing) metabolic pathways, which leads to greater power output. However, excessive, long-term supplementation has been linked to renal problems and other associated toxicity [2][3].

Exogenous erythropoietin (AKA epoetin), on the other hand, increases the percent of red blood cells in a given volume of blood (called the hematocrit) by stimulating RBC production in bone marrow. A higher hematocrit means more oxygen per unit of blood, meaning higher possible oxygen utilization (increased VO2max) [4][7]. This improves all aspects of performance, but cardiovascular endurance exercise benefit the most. Note that an excessively high hematocrit can cause a condition called polycythemia, in which the viscosity of blood is too high, and the blood can't flow smoothly through the vessels in the body. This can cause thrombosis, distal appendage hypoxia, and excessive strain on the heart [4][5].

In a similar practice called blood doping (AKA autologous blood transfusion), an athlete banks their own blood, then receives that as a transfusion to increase blood volume (increasing VO2max etc. etc.). This carries the same risks as epoetin, plus increased BP due to hypervolemia [6].

Very common pharmacological agents, sympathomimetic amines (better known as amphetamines), are often used as stimulants to improve performance. The risks associated with these drugs are very high, however, as they can induce certain kinds of cardiac arrhythmias and delay the sensation of fatigue, which causes athletes to push themselves too far and injure or even kill themselves [1].

β-receptor antagonists, or β-blockers, are primarily used in the medical field to manage tachycardia (high heart rate) and hypertension (high blood pressure). [4] They can also be used athletically to reduce anxiety, slow the heart rate, and reduce the small movements associated with breathing and the heartbeat. In athletes with existing (perhaps undiagnosed) cardiopulmonary conditions, β-blockers can exacerbate those conditions. A few side effects include bronchospasm in asthmatics, heart block in bradycardics, and hypoglycemia in diabetics [1].

Caffeine, often found in the form of pre-workout supplements, is a stimulant so common I won't even bother linking Wikipedia for it. It reduces fatigue and improves free fatty acid mobilization, as well as improving concentration, mood, and reaction time. Bear in mind that chronic caffeine intake is known to cause hypertension due to its vasoconstrictive mechanism [8].

Two hormonal agents, human growth hormone (hGH) and testosterone (anabolic steroids), are used to augment the natural muscle building capabilities during exercise. The benefits of both are fairly clear, so I'll skip right to the bad side. Both steroids and hGH are linked to hypertrophic cardiomyopathy, which is the #1 cause of sudden death in athletes [7]. Steroids can also cause infertility [9], markedly depressed HDL (good cholesterol) levels [1], and prostate enlargement, which increases the risk of prostate cancer [1][10]. These two agents are the only ones in this list shown to have long-lasting effects beyond their metabolic life [1].

TL;DR: Drugs are bad mmkay. But seriously, if you actually want to improve your long-term performance, supplementation isn't the way. Most supplements only improve performance for a short time, and the ones that last longer are irresponsibly dangerous. A proper workout routine that follows the FITT-VP model (frequency, intensity, time, type, volume, progression) as described by the ACSM has significantly longer-lasting positive effects and zero negative effects compared to ergogenic aids.

References

1. Kenney, W. L., Wilmore, J. H., & Costill, D. L. (2012). Physiology of sport and exercise (5th ed., pp. 396-418). Champaign, IL: Human Kinetics.
   
2. Jenkins MD, M. A. (1998). Creatine supplementation in athletes: Review. In SportsMed Web. Retrieved from http://www.rice.edu/~jenky/sports/creatine.html
   
3. Persky, A. M., & Brazeau, G. A. (2001, June). Clinical pharmacology of the dietary supplement creatine monohydrate [Electronic version]. Pharmacological Review, 53(2), 161-176. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/11356982
   
4. F.A. Davis. (2015). David's drug guide for nurses (14th ed., pp. 496-499, 832-834). Philadelphia, PA: F.A. Davis Company.
   
5. Gould, B. E., & Dyer, R. M. (2011). Pathophysiology for the health professions (4th ed., pp. 259-260). Philadelphia, PA: Saunders.
   
6. Rodriguez de Oliveira, C. D., Valle de Bairros, A., & Yonamine, M. (2014, June 25). Blood doping: Risks to athletes' health and strategies for detection [Electronic version]. Substance Use & Misuse, 49(9), 1168-1181. doi:10.3109/10826084.2014.903754
   
7. Pescatello, L. S., Arena, R., Riebe, D., & Thompson, P. D. (Eds.). (2014). ACSM's guidelines for exercise testing and prescription (9th ed., pp. 12t, 73-75). Philadelphia, PA: Lippincott Williams & Wilkins.
   
8. Hartley, T. R., Sung, B. H., Pincomb, G. A., Whitsett, T. L., Wilson, M. F., & Lovallo, W. R. (2000, July). Hypertension risk status and effect of caffeine on blood pressure [Electronic version]. Hypertension, 36(1), 137-141. doi:10.1161/01.HYP.36.1.137
   
9. Crosnoe, L. E., Grober, E., Ohl, D., & Kim, E. D. (2013, June). Exogenous testosterone: A preventable cause of male infertility [Electronic version]. Translational Andrology and Urology, 2(2), 106-113. doi:10.3978/j.issn.2223-4683.2013.06.01
   
10. Anderson, R. A., Bancroft, J., & Wu, F. C. (1992, December). The effects of exogenous testosterone on sexuality and mood of normal men [Electronic version]. Journal of Clinical Endocrinology & Metabolism, 75(6), 1503-1507. doi:10.1210/jcem.75.6.1464655
    
    Edit: Inserted Amazon links to the books I cited if anyone's seriously interested in learning more about clinical exercise physiology. I linked the most recent version; some of the copies I have are older.

This is what I have in my library off the top of my head:

Magee - Orthopedic Assessment - Good for special tests, differential diagnosis, and general background knowledge. This is the first textbook many PT schools ask their students to purchase.



Joint Structure and Function - A good biomechanics textbook if you're interested. I remember it being assigned in both my undergrad kinesiology class as well as Biomechanics and Adv. Biomechanics in PT school.


Observational Gait Analysis - Good gait analysis text but super detailed. It is out of Ranchos Los Amigos, one of the foremost gait mechanic analysis institutions in the US.



Mulligan - Manual Therapy - A great resource, but Mulligan was kind of a strange fellow so keep that in mind.


Manual Therapy - Advanced - Great read, but honestly kind of pricey and probably not worth the cost for an OT. PT though? Definitely recommend.



American College of Sports Medicine - Super convenient to have. Great for medical exercise dosage and cardiopulmonary considerations.


Therapeutic Exercise Foundations - Good read, with some manual therapy thrown in.

If you're super intense, though, you'll want Sahrmann's Book.


To be honest, as a student of any discipline, I'd recommend just making a free account on hep2go.com and looking through their exercises to brush up. The above reads are great if you are interested, though, and I'd recommend for any PT library.



Hope this helps!