Saturday, May 25, 2013

The Female Athlete Triad

I recently presented a short piece on the female athlete triad at school. While it wasn't a particularly thrilling topic to me, I did come across some concerning information. The problem being that there is a lack of knowledge on the issue. From doctors and coaches to the affected women themselves, they need to be made aware of the symptoms and consequences of the triad.

What is the Female Athlete Triad? 
The triad refers to the interrelationships between energy availability, bone mineral density, and menstrual function (ACSM, 2007). Triad, referring to the three aforementioned components exists as a condition when energy availability is insufficient to supply adequate energy for normal physiological processes like menstruation and subsequently maintenance of bone mineral density (BMD).

The diagram below from the American College of Sports Medicine's position stance describes the relationship of the three components of the triad.

When energy availability is kept high, normal menstrual function and optimal bone health are maintained (ACSM, 2007).
Common Signs or Symptoms of the Triad
- Irregular or absent menstrual cycles
- Always feeling tired and fatigued
- Problems sleeping
- Stress fractures and frequent or recurrent injuries
- Often restricting food intake
- Constantly striving to be thin
- Eating less than needed in an effort to improve performance or physical appearance
- Cold hands and feet

So, what's the big deal?
Immediately, decreased bone mineral density leaves an athlete susceptible to stress fractures. But more importantly, for younger adults decreased BMD during young adulthood means they will be more likely to experience osteoporosis and fractures as they age. Further, the BMD that is lost will not be replaced by estrogen replacement therapy, weight gain, or the return of regular menstrual cycles  -- once you've lost it, it may not come back (Burke & Deakin, 2010). Therefore, prevention and early recognition of the triad are crucial to prevent future problems.

Perhaps the most alarming thing about the triad is that most people do not know what it is, the symptoms of it, or its long term consequences. A study from Troy et al. found that in the United States, 52% of physicians, 57% of physical therapists, 62% of athletic trainers and 92% of coaches could not identify all three components of the triad. Of the physicians surveyed, only 9% replied that they were comfortable treating individuals with the triad (2006).

Clearly, there is a lack of knowledge of the topic. So, today I want to try to educate others by providing some information about screening for and preventing the triad.

Prevention
The triad essentially boils down to energy availability. The athlete must consume enough energy to maintain regular physiological processes. Energy availability (EA) refers to the amount of dietary energy remaining after physical exercise. Therefore EA can be calculated as energy consumed minus energy expended during exercise. It is not difficult for most active women to meet EA requirements, but it can be complicated by heavy training or eating disorders.

For maintenance of BMD and reproductive health, a number of sources recommend an EA of 30 kcal/kg fat free mass/day (ACSM, 2007Ihle & Loucks, 2004; Loucks & Thuma, 2003). Applying this rule, a 55kg athlete with 14% body fat -- having 47.3 kg fat free mass (55 - 55*0.14 = 47.3), would need to consume a minumum of 1419 kcal/day before exercising. With an additional hour of running at 8:00/mile (-690 kcals) the athlete is at a minimum of  2109 kcal/day.

The problem with using this equation is that we don't all have DEXA scans or BOD-PODS to know our body fat percentage. Sure, we can estimate. We can also estimate energy expenditure from exercise. The 690 kcals from above came from Vivian Heyward's Advanced Fitness and Exercise Prescription, and is at best another estimate. Why take the time to calculate out EA if two of the variables are just estimates? Then there's the problem of reporting calories consumed. It just isn't practical to measure and record everything we eat every day, and try to calculate caloric intake. Further, if you have an athlete that is at risk for the triad, it is possible she has an eating disorder and she may not report her intake honestly.

A number of studies have demonstrated that appetite is not a reliable indicator of energy availability (Blundell and King, 1998; King et al., 1997;Westerterp et al., 1992). Therefore, “Athletes must learn to eat by discipline to preserve their reproductive and skeletal health” (Burke and Deakin, 2010).

As an Athlete
Instead of focusing strictly on dietary intake, educate yourself and know the symptoms of the triad -- monitor your menstrual cycles, performance, and know that stress fractures may be an indicator of sub-optimal bone health. Seek help from coaches, physicians, nutritionists if you suspect your body weight is too low, you have disrupted menstrual cycles, or any of the symptoms listed above.

Do Not Diet! Without proper supervision of a dietitian or nutritionist. Know that food is fuel for performance and recovery.

The Role of Coaches
Perhaps the most promising form of prevention is educating the professionals working with athletes. It is our job as coaches to be educated, aware, and to monitor our athletes. With that said -- if you work with female athletes, educate yourself on the symptoms of the triad. I strongly recommend reading the ACSM position stand and the IOC's position stand.

 As a coach, if you suspect an athlete to be at risk for developing the triad, screen them for it. If you feel comfortable enough, you can screen them yourself. If not, refer them to a physician that can. The screenings can be verbal or written form and should include questions about the athletes performance, body image, diet, injury status, and menstrual cycles. Below is a list of questions from the IOC's position stand that should be included in a screening.
The Female Athlete Triad, 2006. International Olympic Committee.
If you believe an athlete exhibits symptoms of the triad, refer them to a physician or dietitian for treatment.

Another role of the coach is to encourage athletes to eat for optimal performance, not weight or body image. Of course, coaches should be there for their athletes to encourage them and provide them with positive feedback and support. And finally, coaches should enlist others in treating individuals. Athletic coaches are not generally qualified to treat conditions or prescribe dietary interventions. Therefore, he should have a network of professionals to refer athletes to when needed. Treatment will likely be a multidisciplinary approach enlisting physicians, therapists, nutritionists, etc.

Coaches should also make their athletes aware of consequences of the triad, being diminished reproductive and bone health that can have life-long implications.

The ACSM sums up prevention of the triad in one sentence, "Athletic administrators and the entire health-care team should aim to prevent the triad through education.” If you've read this post, you're off to a good start but this certainly is not a comprehensive guide to the female athlete triad.

References
Blundell, J. E., & King, N. A. (1998). Effects of exercise on appetite control: loose coupling between energy expenditure and energy intake. Int J Obes Relat Metab Disord, 22 Suppl 2, S22-29.

Burke, L., & Deakin, V. (2010). Clinical sports nutrition (4. ed.). New York: McGraw-Hill Medical.

Heyward, Vivian. 2010. Advanced Fitness Assessment and Exercise Prescription. Sixth Edition. 

The Female Athlete Triad. (2007). Medicine & Science in Sports & Exercise, 39(10), 1867-1882.

Ihle, R., & Loucks, A. B. (2004). Dose-response relationships between energy availability and bone turnover in young exercising women. J Bone Miner Res, 19(8), 1231-1240.

King, N. A., Lluch, A., Stubbs, R. J., & Blundell, J. E. (1997). High dose exercise does not increase hunger or energy intake in free living males. Eur J Clin Nutr, 51(7), 478-483.

Loucks, A. B., & Thuma, J. R. (2003). Luteinizing Hormone Pulsatility Is Disrupted at a Threshold of Energy Availability in Regularly Menstruating Women. Journal of Clinical Endocrinology & Metabolism, 88(1), 297-311.

The Female Athlete Triad (2006). International Olympic Committee.

Troy, K., Hoch, A. Z., & Stavrakos, J. E. (2006). Awareness and comfort in treating the Female Athlete Triad: are we failing our athletes? WMJ, 105(7), 21-24. 

Westerterp, K. R., Meijer, G. A., Janssen, E. M., Saris, W. H., & Ten Hoor, F. (1992). Long-term effect of physical activity on energy balance and body composition. Br J Nutr, 68(1), 21-30.

Wednesday, May 22, 2013

Purpose

Vern Gambetta posted last week on ELITETRACK Blogs about how athletes are taught to do drills, but they often go through the motions completing them without purpose, without proper form, or without the power required to get any benefits from the movements.

If you're performing work; whether it's a drill, a hill sprint, or a long run, do it with purpose and set yourself up to nail the purpose of the workout. Recognize that hard work for the sake of working hard is not always good work, but hard work with a specific purpose is the way to winning.

Tuesday, May 14, 2013

More on Hills

Scott Douglas of Runner's World wrote here last month about a new study investigating the effects of various uphill intervals on 5k time trial performance. As a student that has spent some time writing about hill sprints and running economy (RE) and planning a research project on the topic, this little blurb peaked my interest and I've been on the look-out for the publication ever since. Well, it has been accepted for publication but hasn't published just yet. Nevertheless, I have accessed the submitted, unedited version.


Barnes, K. R., Hopkins, W. G., McGuigan, M. R., & Kilding, A. E. (2013). Effects of Different Uphill Interval-Training Programs on Running Economy and Performance. Int J Sports Physiol Perform


An abstract can be found here on PubMed.

To summarize, 15 male and 5 female trained distance runners were evaluated for VO2max, RE, countermovement-jump peak force, and 5k time.  The 20 subjects were then assigned to 1 of 5 groups. Each group completed a specific type of uphill  interval training twice a week in addition to their normal training routine.

Below is a list of the five groups along with a brief description of the intervals they performed.

Group 1 (n = 3) -- 12-24 reps of 8-12s hill sprints, ~60s recovery; 18% gradient

Group 2 (n = 5) -- 8-16 reps of 40-45s, ~ 90s recovery; 15% gradient

Group 3 (n = 5) -- 5-9 reps of 2-2.5 min, ~ 4.5 min recovery; 10% gradient

Group 4 (n = 4) -- 4-7 reps of 4-5 min, ~6-7 min recovery; 7% gradient

Group 5 (n = 3) -- 1-2 reps of 10-25 min, equal recovery; 4% gradient

After completing 6 weeks of training with their respective intervals, the subjects returned to the lab to evaluate VO2max, RE, peak power, and 5k time.

Results:  At best, one group improved their VO2max 4.1%. 5k time was improved ~2.0% (~20s) in all groups. The most interesting piece of information to me is that the group performing the 10s hill sprints showed the greatest improvement in countermovement-jump peak force  (29%) and RE (2.4%). This is the first study to show that hill sprints improve RE. But this study also has some limitations...

First, there was no control group. So, one cannot say that uphill intervals are better than intervals on level-ground -- there is actually some evidence to suggest the opposite.

Second -- Statistical power. With only 3 subjects in a group, seeing a 2.4% improvement in RE, what is the likelihood that their result is not due to an error? I'm not sure, because we are not provided with p values, only percent changes from pre- and post-test measurements; and I am not a statistician. All this means is we cannot be certain that the results seen in this group can be attributed to the intervention (hill sprints); and we cannot definitively say that hill sprints improve running economy.

Third -- Treadmills. It appears that all interval training was conducted on treadmills. I understand the need to standardize speed, gradient, and intensity, but I think there are limitations to treadmill training. Hill sprints for example: hill sprints are balls-to-the-wall effort, not calculated at 120% vVO2max using an equation to extrapolate simulated velocity due to the incline of the treadmill. Just go outside and run up an 18% gradient for 8-10s as fast as possible -- Only then will you get a true maximal effort.

Fourth -- Male and female subjects? We are not told if any effort was made to accommodate for the women's menstrual cycles. Further, we do not know if the five female subjects were evenly distributed among the groups. And who knows? Women may not respond to uphill interval training in the same way men do.

But, despite the limitations of the study, it has shed some light on the topic of hill sprints and running economy and their relationship to 5k performance. In the academic world, we can now say that there is some evidence to suggest that short hill sprints do elicit similar improvements in peak power and RE as plyometrics and resistance training. But it seems coaches and athletes have known this for the last 50 years. It's only fitting that this study came out of New Zealand -- home to one of the pioneers of hill training, Arthur Lydiard.

Another interesting tid-bit from this study is that VO2max was improved the most between groups 3 and 4. Why did these groups see the largest improvements in VO2max? The authors theorize it was because these groups were training at intensities simulating VO2max.

I would like to see a comparison of muscle damage between runners doing level-ground interval training and uphill interval training. Just as coaches have been touting the benefits of uphill running for running economy, they also say uphill running is easier on the legs and may help prevent injuries...

In summary -- uphill interval training may be beneficial for runners. It can improve performance, RE, peak power output, increase stride rate and so on... but then again, so can level-ground interval training...

Monday, May 6, 2013

Fructose, Sucrose, or Glucose?

While I am sidelined with an angry low back today (more on that later), I thought I'd take the time to write a bit about carbohydrates (CHO). Specifically, the different types of CHO and their effects on blood glucose and glycogen replenishment.

CHO ingestion has been found time and time again to aid in intense and prolonged endurance performances. Why? Because two of the mechanisms behind fatigue are decreased blood [glucose] and muscle glycogen content. The two go hand in hand, such that when muscle glycogen is depleted, blood glucose will be metabolized -- and when blood glucose is metabolized and not maintained through ingestion of CHO, blood glucose will drop.

Remember glycolysis? Then you remember glucose is necessary to run glycolysis. And there are two sources of glucose for working muscle cells - glycogen and blood glucose. When an athlete has low glycogen and low blood glucose, his ability to run glycolysis will be limited by CHO availability and exercise intensity will decline (Wright et al., 1991).

Blood glucose - In summary, glucose provides substrate for glycogen synthesis and immediate energy through glycolysis. Keeping blood glucose elevated, or preventing the decline of blood glucose during exercise allows the athlete to maintain a greater intensity while training. Does training at higher intensities elicit greater training responses? No doubt. Could training in a glycogen depleted state improve endurance performance? Maybe, maybe not... I am doubtful. It may depend on the athlete's goals, but note there was no difference in the one variable that matters here -- cycling performance.

It's a lot like the research I've been working on lately with David Morris at ASU. Which yields greater performance gains? Hypoxic or hyperoxic training? Can training with hyperoxic gas (60% O2) improve time trial performance at a simulated altitude of 14,000 ft? Hyperoxic gas enables the athletes to train at a higher work rate (as does training with saturated glycogen stores) on the bike and training at a higher work rate may elicit a greater training response. Further, can training with hyperoxic gas improve TT performance more than training with hypoxic gas (13% O2). The decreased oxygen content significantly reduces the work rate the athletes can sustain during training (like training in a glycogen depleted state) -- but might they get other adaptations from training at altitude? Our preliminary results are intriguing.

But, getting back to maintaining glycogen stores: To maintain training intensity, how can one keep glycogen stores and blood glucose high?


Take a look at the figure above and note, it all boils down to carbohydrate intake. But not all carbohydrates are the same. Muscle metabolizes glucose, and that glucose comes from a number sources in the diet:


     1) Glucose and/or glucose polymers
     2) Fructose, sucrose, galactose, and other sugars not glucose
     3) Amino Acids
     4) Fatty Acids
     5) Alcohol

Blood Glucose
As you might have guessed, numbers 3,4, and 5 are not favorable substrates for raising or maintaining blood glucose levels -- but they can be converted to glucose in the liver in dire situations. Fructose is similar. Fructose cannot be metabolized by working muscle as fructose. Instead, it must be transported to the liver and converted to glucose.  But, some of that fructose will not be converted to glucose. Some of it may be converted to lactate. Not only can conversion of fructose to lactate increase blood [lactate], the CHO available to working muscles will be lower than if the same amount of glucose had been ingested. Note, I lumped sucrose with fructose, because it is not technically glucose. Sucrose is a disacharride made of one molecule of  fructose bound to one molecule of glucose. Despite being 50% glucose, when the same amount is consumed, sucrose will not elevate blood glucose as much as glucose alone (Murray et al., 1989).

Insulin
Another problem with fructose and sucrose is that they do not stimulate insulin secretion to the degree of glucose does -- even when equal amounts are consumed. This will be more important following exercise, when insulin is need to help transport glucose into muscle cells and activate glycogen synthase.

Absorption Rate
Further, glucose has a faster intestinal absorption rate (and helps with water absorption). Glucose is actively transported out of the small intestine. Fructose, however, must be passively absorbed -- delaying intestinal absorption rate, and possibly leading to gastric distress. (Murray et al., 1989)

In summary - glucose is the superior form of CHO to ingest in and around exercise. It is actively transported out of the gut, it raises blood glucose directly and can be metabolized by working muscle immediately, and after exercise, it is a better secretagogue of insulin - enabling transport into muscle cells, activating glycogen synthase and restoring glycogen more rapidly than other forms of carbohydrate (Murray et al., 1989; Bowtell et al., 2000).

What does this mean for the athlete?
     When training, pass on the sodas, pass on the fruit juice, pass on the Powerade... And go for the drinks that contain maltodextrin, glucose, dextrose, and maltose.

References


Bowtell, J. L., Gelly, K., Jackman, M. L., Patel, A., Simeoni, M., & Rennie, M. J. (2000). Effect of different carbohydrate drinks on whole body carbohydrate storage after exhaustive exercise. J Appl Physiol, 88(5), 1529-1536. 

Murray, R., Paul, G. L., Seifert, J. G., Eddy, D. E., & Halaby, G. A. (1989). The effects of glucose, fructose, and sucrose ingestion during exercise. Med Sci Sports Exerc, 21(3), 275-282.

Wright, D. A., Sherman, W. M., & Dernbach, A. R. (1991). Carbohydrate feedings before, during, or in combination improve cycling endurance performance. J Appl Physiol, 71(3), 1082-1088.