tjtryon's Group - Closed (Page 3)

Ok
I just for some reason had that idea before, that I couldnt go biking for a short period of time. Anyways, I can't really go biking until I get my bike fitted tomorrow, so I don't get any back pain.
I'm just going for an easy run today and maybe hop on a stationary bike later to curb my thirst to be on my bike!

I have a few guys that I coach, and one of the reoccouring themes for our group runs is bouncing in their stride. Here's an email I sent to them today. Hopefully you may find it helpful - heck, this is something I think I will likely always be working on myself.

I did it! I am officially a "Triathlete". Yea!!! Had my first race this morning, a small race in Plymouth IN called the "Magee 3". It's a race in honor of the race director's and wife's unborn son who was killed in a car accident 7 years ago. This is the 6th annual race.

I accomplished all my goals. I had fun, finished with a smile on my face and finished in 1:20:56, 4 minutes under my initial goal time. I don't have the exact transition times, but I did 10:23 in the swim for 440 yds, 37:59 on the bike for 10.5 miles and 30 minutes on the run for 3.5 miles. Not sure what place I finished yet. I'll know that later. But I didnt' finish last by a long shot. Even though I was one of the last people coming out of the lake, I did catch several people on the bike and a few on the run, so that was good.

My wife and 3 kids came along to cheer me on and my 8 1/2 year old daughter took a bunch of pictures. It's the first time they've ever seen my compete in an athletic event so that had a special meaning.

The people were very nice and I knew a couple of them. It was neat to see how the leaders had encouraging comments to say as they either passed you coming back on the run, or were out taking their warm-down runs as I was coming back in. I made sure to also say "good job" to people as I passed them.

I've got my race report up. Two more weeks and I've got another race in LaPorte, IN. Thanks to everyone for the encouragement.

Congratulations dude!!!

That's awesome!!! I'm glad it went well for you, and it sounds like you had a great time doing it!
Great times for your first Tri FOR SURE!!!
Getting 4 minutes under your goal time on your first race where it's hard to know what to expect is awesome!

And also, congratulations on becoming a Triathlete!!

Thanks. It was fun. I'm glad I did it, and now I feel better going into my next race in two weeks. I hope to have a good couple of weeks training. I ran 5.5 miles this morning and felt very good (after I stretched). Then I just got home from a 17 mile recovery ride. I was going over my race report on BT with my wife last night and one of the things I listed that I could do better for T1 was either go shirtless or get a Tri-Suit. She said, get a tri-suit. You're too good looking to go shirtless. Evidently she didn't want a bunch of other women looking at me. But the cool thing is, my wife hasn't said anything like that in years, so my Tri training is paying dividends in other areas as well. Gotta like that!

Congratulations!! I'm sure you're feeling great. Keep up the great work. And I'm glad that you're making your wife happy Good luck in two weeks.

So I finished the Vineman, my first HIM today! It was so awesome... Challenging, but awesome. Here's the report!

Swim - started the swim late because we got lost on the way to the start, so my actual time was a little less bec I didn't start with my heat.

Cycling - was amazing! Chalk Hill was really difficult... but in the end I stood up and got through it.

Running - the run was hotter than hell -- i think it was about 90-some degrees, but the winery you go through is so beautiful. in fact, the whole course if beautiful!

Swim: (120/132 age group)
Started late--they have me at 57:27, but I had 53 on my watch

T1: 5:32.3

Bike: (80/120 age group)
3:18:11, 18.6 miles/hr, average

T2: 4:22.4

Run: (71/118 age group)
2:17:38, 9:10/mile average

Overall: (400/1823 overall, 85/118 age group)
6:43:11.5

Wow Great job on the HIM!
That sucks about the swim start but not a whole lot you can do really!

I'm planning on doing my first one next year, as I dont think I could do the whole 90 km bike thing this year!

Again, Great job!!!
Planning on doing an IM anytime soon?

Awwww thanks! Yeah, I was so happy with the experience. It was so inspiring. I was beaten by 10 or so 50 yr old women and a 60 and 63 year old. These people are my personal heroes and I can't believe I get to be on the same course with them. They are just amazing.

Holding off on IM distance, since I have a knee injury (that's why I started HIM in the first place--my ortho said no more marathons for now bec of my knee ...hopefully someday I will be strong enough to run 26 miles again, but for now, I want to "master" the HIM!

Great job on the HIM. I have trouble driving for 6+ hours straight, let alone swimming, biking, and running. I think I'll stick to the Sprints for the time being. With a FT job, a wife, and 3 little kids, it's hard enough as it is to carve out training time.

I'm proud of you. Keep up the good work. And don't ever forget the real HIM who gives you the ability, power, and strength to do what you're doing.

Question for TJ -

Can you give any suggestions on fuel for the race, i.e. hydration, gels, energy bars? How much should I drink on the bike for a Sprint? And what is the best to drink? Water only? Water and energy drink mixed? Energy drink only? Also, what can you tell me about gels and energy bars. should I eat those during a race? If so, when? Finally, my calves start twitching after the bike when I first start running. Is there something I can do to prevent that? Do I need to hydrate more on the bike? Thanks.

Wow, lots of questions. I guess it's best to start saying do whatever it takes to keep you hydrated, keep your electrolytes in check, and keep enough fuel in your body to not bonk. Some of this is easy, some is a little bit of your experience. On to the easy part:

Fuel- For a sprint, really, there is no need to worry about hard fuel. Your muscles and liver store about 200-3000 calories worth of fuel, which is enough to get you through a hard effort for 2.5 hours. My rule of thumb for myself, for any race over 1 hour and under 2 hours, I typically try to take in no more than 100-250 calories, between a watered down sports drink, and possibly a gel or shot block - especially if the race is going to approach 2 hours. For races closer to 1 hour, I typically forgo the hard nutrition and stick with hydration - sports drinks. Any effort above 2 hours, I typically try to have about 250 calories per hour, as a mix of easy to digest liquids, gels and shot blocks. I have on occasion taped a clif bar or banana to my top tube for long races - I can only consume so much gel before I get bored.

Example: 4:20 marathon (<10 minute pace): 250 calories per hour * 4.3 hours = ~1075 calories for the race. Mix and match how you want. I find it easier to digest liquids, then gels, then blocks, then bars, then real food in that order. Most races have food/beverages/gels/etc. on the drink stations - try to find out which brands, and train with those brands up front to see what works for you. If you don't have to carry gel packets and liquids on a long race, fantastic.

Make sure you know your nutrition/hydration plan up front, before the race, so it is not a guessing game. Sometimes your experience GI shutdown from longer races - you can't eat, and in some instances - can't drink. There will be those times, just plan for them ahead of time, and know what you can do yourself to combat this and to most importantly force down and keep down liquids, either in water form, or sports drink form. More on hydration later.

Electrolytes- Fluid loss plays a major factor in performance. Studies show that when you lose 2-3% of the body's fluid through sweat, performance decreases by up to 7%. This can be the difference between winning and not even finishing. Electrolytes promote the absorption of water during exercise. When you sweat, you lose essential electrolytes, which can result in muscle cramping and dehydration. Ever have salt stains on your hat, shirt or shorts after a really hard workout? That's your body loosing fluid (hydration) and electrolites (salt). The transfer of nutrients and water in and out of the cell known as cellular respiration requires all five electrolytes in a precise balance for maximum cellular efficiency.

Dedicated long course endurance athletes require much higher levels of electrolytes than can be found in most drinks - by endurance, I am talking about over 2 hour intensity - these athletes will most likely benefit from electrolyte supplimentation more than your typical sports drink (see my rant on Gatorade below). For your typical sprint, your electrolyte sports drink should be sufficient, providing you are hydrating regularly, unless your event is approaching the 2 hour mark. For the longer course athlete, electrolyte replacement is a must. If you hydrate with water alone, and you dilute your sodium levels, you end up with hypotonic hydration, which can and will kill you. This is why it is critical to keep your electrolytes in balance with your hydration. I personally have recently starting using Endurolytes capsuls for my events, and have been tolerating well. gatorade rant: I had problems with drinking too much Gatorade, as the sodium level is so high, if I use gatorade to handle electrolyte replacement, I wake up the next morning swollen (hands, feet, face, legs) from an excess of water. Make sure you know how well you tolerate whichever sports drink or electrolyte replacement method you decide to use, and make sure it is not just sodium, but you are getting all your electrolytes replaced (and in the best balance for you - do your research). sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl-), phosphate (PO43-), and hydrogen carbonate (HCO3-) are the electrolytes you need to make sure you keep certain levels of - not too little or not to much.

Hydration: I'll have to get back to this part shortly, work is calling...

UPDATE:



Hydration is a very intense subject, tomes have been written on the subject and there is a ton of good information out there. Below, you will find I belive the writeup of the original Gatorade study data - the information that came from studying a little football team in Florida (Gators) and how they trained in the heat. Some of this data was what led to the original formulation of Gatorade, I believe. Interesting read, be sure to take the time, it is WELL worth the 10 minutes it takes to get through it.

Important Highlites:
1) Dehydration is bad - bad for your body (elevated core temp, elevated heart rate/respiration), bad for your performance.
2) Know your sweat rate. Every pound you loose per hour exercising in the heat is a 15 oz water bottle full of liquid you needed to drink. You do weigh yourself before and after your workouts, right?
3) Drink enough liquid to stay hydrated.
4) Using a sports drink with carbohydrates and proper electrolyte replacement in the approporate amounts is the best thing for endurance efforts.

Hydration:

Edward E Coyle, Ph.D.

SPORTS SCIENCE EXCHANGE

FLUID AND CARBOHYDRATE REPLACEMENT DURING EXERCISE: HOW MUCH AND WHY?

SSE#50, Volume 7 (1994), Number 3

--------------------------------------------------------------------------------

Edward E Coyle, Ph.D.
Director., Human Performance Laboratory
Department of Kinesiology and Health Education,
The University of Texas at Austin
Austin, Texas
Member, Sports Medicine Review Board
Gatorade Sports Science Institute

KEY POINTS

1. During prolonged exercise in the heat, people can become dehydrated at a rate of 1-2 L every hour (about 2-4 lbs of body weight loss per hour). The rate of dehydration can be monitored by recording changes in nude body weight. Each pound of weight loss corresponds to 450 mL (15 fluid ounces) of dehydration.

2. Even a slight amount of dehydration causes physiological consequences. For example, every liter (2.2 lbs) of water lost will cause heart rate to be elevated by about eight beats per minute, cardiac output to decline by 1 L/min, and core temperature to rise by 0.3o C when an individual participates in prolonged exercise in the heat.

3. When it is important to minimize disturbances in cardiovascular function and body temperature and to reduce the perceived difficulty of exercise, people should attempt to drink fluids at close to the same rate that they are losing body water by sweating.

4. Unfortunately, runners generally drink only 300-500 mL of fluids per hour and thus allow themselves to become dehydrated at rates of 500-1,000 mL/h. Dehydration compromises cardiovascular function and places the runner at risk for heat-related injury. The runner must answer the question, Will the time I lose by drinking larger volumes of fluid be compensated for by the physiological benefits the extra fluid produces that may cause me to run faster during the last half of the race?

5. For an exerciser who weighs about 68 kg (150 lb), the requirements for both carbohydrate (i.e., 30-60 g/h) and fluid during prolonged exertion can be met by drinking 625-1,250 mL/h of beverages containing 4-8% carbohydrate. This volume must be adjusted for persons of different body weights. For example, an individual who weighs 50 kg should multiply the above recommendation by 50/68 or 0.74, i.e., 462.5-925 mL/h.


INTRODUCTION

The prevalent thinking from the turn of the century until the 1970's was that participants in endurance sports did not need to replace fluids lost during exercise (Noakes et al., 1991a; Noakes, 1993). This misconception has now given way to the knowledge that drinking fluids reduces the increase in body temperature (hyperthermia) and the amount of stress on the cardiovascular system, especially when exercising in hot environments (Coyle & Montain, 1993). However, the extent to which even a slight degree of dehydration adversely affects bodily function during exercise and the situations in which adding carbohydrate and salt to water provides added benefit are not generally appreciated. The volume of fluid that most athletes choose to drink voluntarily during exercise replaces less than one-half of their body fluid losses (Noakes, 1993). The purpose of this paper is to review the physiology of fluid and carbohydrate replacement during exercise and the likely effects of such replacement on the performance of pro-longed exercise. It is hoped that this knowledge might encourage competitors to drink more during exercise.


FLUID INGESTION DURING PROLONGED EXERCISE

The decision as to how much fluid to ingest during exercise should be based upon a risk-benefit analysis. Undoubtedly, the most serious consequence of inadequate fluid replacement, i.e., dehydration, during exercise is hyperthermia, which when severe will cause heat exhaustion, heat stroke, and even death. The risks of too much fluid ingestion are gastrointestinal discomfort (Rehrer et al., 1990) and a reduced pace during competition associated with the physical difficulty of drinking large volumes of fluid while exercising. The benefits of fluid ingestion are reduced cardiovascular stress and reduced hyperthermia that, by themselves, can probably improve exercise performance.



CARBOHYDRATE INGESTION DURING PROLONGED INTENSE EXERCISE

The primary purpose of carbohydrate ingestion during strenuous exercise lasting longer than one hour is to maintain a sufficient concentration of blood glucose and to sustain a high rate of energy production from blood glucose and glycogen stored in muscles (Coggan & Coyle, 1991; Coyle et al., 1986), which can allow competitors to exercise longer and sprint faster at the end of exercise (Coggan & Coyle, 1991 ). Most studies demonstrating improved performance with carbohydrate feedings have given subjects 25-60 g of carbohydrate during each hour of exercise (Coggan & Coyle, 1991; Murray et al., 1991). We therefore recommend that individuals consume solutions that provide 30-60 g of carbohydrate per hour in the form of glucose, sucrose, or starch (Coggan & Coyle, 1991 ).

It was previously thought that the addition of carbohydrate to solutions impaired fluid replacement because carbohydrate is known to slow the rate at which fluids empty from the stomach (gastric emptying). However, the most important factor regulating gastric emptying and fluid replacement is the volume of fluid ingested; the carbohydrate concentration of the solution is of secondary importance (Coyle & Montain, 1992a; Coyle & Montain, 1992b, Mitchell et al., 1989; Noakes et al. 1991b; Rehrer et al. 1990). Practically speaking, solutions containing up to 8% carbohydrate appear to have little deleterious influence on the rate of gastric emptying, especially when the drinking schedule adopted maintains a high gastric volume (Coyle & Montain, 1992b; Houmard et al., 1991; Mitchell et al., 1988; Noakes et al., 1991b). Thus, it is quite possible to ingest 30-60 g of carbohydrate per hour and still replace 600-1,250 mL of fluid per hour. Our experience is that cyclists have no difficulty drinking 1,200 mL/h of a 6% carbohydrate solution.

Difficulties in Drinking Large Volumes of Fluids While Running

Large gastric volumes will no doubt cause discomfort in some runners. Therefore, in runners, it remains to be deter-mined if the performance benefits of high rates of fluid replacement outweigh the discomfort it may cause. We suspect that many marathon runners allow themselves to become dehydrated to some extent because they feel their stomachs cannot tolerate the large volumes of fluid that must be drunk to totally offset sweat losses. In general, most runners drink less than about 500 mL of fluid per hour (Noakes et al, 1991 a; Noakes, 1993). Because sweat rates often average 1,000-1,500 mL/h, marathon runners commonly become dehydrated at a rate of 500-1,000 mL/h, although dehydration rates can be much higher when the fastest runners compete in hot environments. Unfortunately, drinking large volumes of fluid cost the runner additional seconds in approaching the aid-station table and in attempting to drink and breathe while running. Furthermore, the added gastrointestinal discomfort may cause the competitor to run at a slower pace until the discomfort subsides. The runner must answer the question of whether the time lost while drinking larger volumes of fluid will be compensated for by the physiological benefits the extra fluid produces that may cause me to run faster during the last half of the race. However, if the goal is safety, which means minimizing hyperthermia, it is clear that the closer that the rate of drinking can match the rate of dehydration, the better.

To our knowledge, no studies have directly compared the effects on running or cycling performance of fluid replacement at rates that prevent dehydration versus rates voluntarily chosen by many endurance athletes (e.g., 500 mL/h) who replace only 30-50% of fluid losses. The cardiovascular benefits of full compared to partial fluid replacement when cycling are discussed below, and it is likely that the same cardiovascular benefits are derived when running.


LOW INTENSITY EXERCISE AND FLUID REPLACEMENT

In experiments conducted about the time of World War II, it was repeatedly found that fluid ingestion during prolonged low-intensity exercise such as walking and stair stepping attenuated deep body (core) temperature and improved exercise performance (Adolph, 1947; Bean & Eichna, 1943; Eichna et al. 1945; Pitts et al., 1944). Fluid ingestion equal to the rate of sweating was more effective than voluntary or partial fluid replacement (Bean & Eichna, 1943; Eichna et al., 1945; Pitts et al., 1944). Furthermore, voluntary fluid ingestion during low-intensity exercise is more effective in attenuating hyperthermia than when fluid intake is totally prohibited or is restricted to small volumes (Eichna et al. 1945; Pitts et al. 1944). Thus, during prolonged, low-intensity, intermittent exercise, the optimal rate of fluid replacement for attenuating hyperthermia appears to be the rate that most closely matches the rate of sweating.


CARDIOVASCULAR AND THERMOREGULATORY BENEFITS OF HIGH RATES OF FLUID REPLACEMENT DURING INTENSE CYCLING IN THE HEAT

To gain some insight into the effects of various fluid replenishment schemes on exercise at the high intensities typically experienced in sport competition, we deter-mined the effect of different rates of fluid replacement during prolonged intense cycling on hyperthermia, cardiac output, and heart rate (Coyle & Montain, 1992a). On four different occasions endurance-trained cyclists exercised in a warm environment (33 _ C, 50% relative humidity) at 62-67% VO2max, which was the highest intensity that could be maintained for 2 h when no fluid was ingested. During 2 h of exercise, the cyclists randomly received either no fluid or drank small (300 mL/h), moderate (700 mL/h), or large (1,200 mL/h) volumes of a sport drink containing 6% carbohydrate and low concentrations of electrolytes. These fluid volumes replaced approximately 20%, 50%, and 80%, respectively, of the fluid lost in sweat during exercise. The protocol resulted in graded magnitudes of dehydration; body weight declined 4%, 3%, 2% and 1%, respectively, when drinking either no fluid or small, moderate, or large volumes of fluid. The increases in core temperature, heart rate, and perceived exertion during the 2 h of exercise were progressively diminished as more and more fluid was consumed (Figure 1 ). The magnitude of dehydration accrued after 2 h of exercise in the four trials was the major factor associated with hyperthermia and cardiovascular stress. Figure 2 demonstrates that the rise in core temperature, the rise in heart rate, and the fall in cardiac output observed after 2 h of exercise were inversely related to the rate of fluid ingestion and directly related to the extent of dehydration experienced. Specifically, every 1 L loss of sweat (2.2 lb of body weight) caused heart rate to increase by eight beats per minute, cardiac output to decline by 1 L/min, and core temperature to increase by 0.3o C. Therefore, we maintain that there is no acceptable amount of dehydration that can be tolerated before cardiovascular function and thermoregulation are impaired. Drinking 1,200 mL/h was better than drinking 700 mL, which in turn was better than drinking 300 mL/h.


Perception of Effort

Although performance was not actually measured in the study just described, sever-al subjects were barely able to complete 2 h of exercise without fluid ingestion (Montain & Coyle, 1992). Drinking progressively larger volumes of fluid reduced the subjective rating of perceived exertion, as shown in Figure 1. After 2 h of exercise, these cyclists rated the exercise as being "very hard" when no fluid was ingested and "hard" when only 300 mL/h of fluid was ingested. (Competitors often drink only a small volume of fluid (e.g., 300 mL/h), which may give a false sense of security by somewhat reducing their sense of perceived exertion while providing only minimal physiological benefit.) However, when fluid was consumed at a rate of 700 mL/h or 1,200 mL/h, the exercise never was rated "hard." It is likely that these perceptions of effort provide indirect information about performance ability after 2 h of cycling with different amounts of fluid replacement. Additionally, none of the cyclists complained of gastrointestinal discomfort or of difficulty drinking 1,200 mL/h. We therefore conclude that this rate of fluid replacement is tolerable during cycling, but we do not know whether it is acceptable when running.


Figure 1. Core temperature (esophageal temperature), heart rate, and perceived exertion during 120 min of exercise when ingesting no fluid, or small (300 mL/h), moderate (700 mL/h) and large (1,200 mL/h) volumes of fluid. A rating of 17 for perceived exertion corresponds to "Very Hard," 15 is "Hard," and 13 is "Somewhat Hard". Values are means-SE. * Significantly lower than no fluid, P < 0.05. Significantly lower than small


POSSIBLE REASONS FOR THE CARDIOVASCULAR BENEFIT OF FLUID REPLACEMENT DURING EXERCISE

The most serious consequence of exercise-induced dehydration is hyperthermia, which places added stress on the cardiovascular system and creates a vicious cycle. Dehydration during exercise causes fluid to be lost throughout the body. As a result, dehydration increases the concentration of dissolved particles in bodily fluids (osmolality), including the concentration of sodium in the blood serum. These increases in osmolality and in sodium concentration seem to play some role in slowing heat loss by reducing blood flow to the skin and by reducing the rate of sweating. An addition-al important effect of dehydration-induced hyperthermia is a large decline in cardiac output, a measure of total blood flow throughout the body. This exacerbates the hyperthermia by further reducing the transfer of heat from the body core to the cooler periphery (Montain & Coyle, 1992a). The most dramatic consequence of dehydration-induced hyperthermia during exercise is a 25-30% reduction in stroke volume that is not generally met with a proportional increase in heart rate; this results in a decline in cardiac output and in arterial blood pressure (Gonzalez-Alonso et al., 1994; Montain & Coyle, 1992a).

The primary benefit of sufficient fluid replacement during exercise is that it helps to maintain cardiac output and allows blood flow to the skin to increase to high levels so as to promote heat dissipation from the skin, thereby preventing excessive storage of body heat (Montain & Coyle, 1992a). The exact mechanism by which fluid replacement pro-motes a high skin blood flow during exercise is not clear. Fluid replacement does help to prevent loss of water from the blood plasma, but in endurance-trained athletes, this improved maintenance of plasma volume apparently does not by itself increase blood flow to the skin to reduce core temperature (Montain & Coyle, 199b). It seems more likely that fluid replacement prevents skin blood flow from declining by preventing dehydration-induced impairments in the neural control of skin blood flow, by preventing declines in blood pressure, and/or by minimizing the exercise/dehydration-induced increases in the blood concentrations of catecholamines, sodium, and other osmotically active particles.


PERFORMANCE BENEFITS OF INGESTING FLUIDS AND CARBOHYDRATE

As discussed previously, fluid replacement during exercise improves work time in subjects walking in the desert, but surprisingly few studies have documented performance benefits of fluid replacement during more intense exercise in laboratory studies or during competitive athletic events (Armstrong et al., 1985; Costill et al., 1970). It is to be expected that fluid replacement would be most beneficial during more prolonged exercise that accentuates the amount of dehydration. As shown in Figure 1, during 2 h of exercise in the heat (33 _ C) at 65% VO2max, the physiological benefits of fluid replacement began to emerge after 1 h of exercise (Montain & Coyle, 1992b). This prompted us to con-duct a performance study during more intense cycling in the heat, performed for a duration of approximately 1 h (Below et al., In Press). After 50 min of exercise at 80% VO2max, heart rate and core temperature were lower by four beats/min and 0.33o C, respectively (P), when a large volume (1300 mL) compared to a small volume of fluid (200 mL) was ingested during the first 35 min of exercise. Performance was then measured as the number of minutes required to complete a set amount of work, so as to simulate the closing stages of a race. Performance time for this last stage of cycling was 6% faster when the large volume of fluid was ingested.

Carbohydrate ingestion clearly improves performance in events lasting longer than 90 min and in which fatigue is associated with reduced bodily stores of carbohydrate ( Coggan & Coyle, 1991), but little is known about the influence of carbohydrate feedings on shorter duration exercise that is more typical of most sport events. Therefore, in the previously cited study (Below et al., In Press), we also determined if ingestion of 70 g of carbohydrate might improve performance of a brief, high-power cycling test following 50 min of cycling at 80% VO2max. Indeed, performance was also improved 6% by carbohydrate ingestion. Therefore, both fluid replacement and carbohydrate ingestion equally improved high-intensity cycling performance, each by 6%. Furthermore, their beneficial effects were additive, i.e., there was a 12% improvement in performance when both fluid and carbohydrate were administered, and these effects apparently operate through independent mechanisms (Below et al., In Press).


EXERCISE/DEHYDRATION-INDUCED HYPERTHERMIA IN VARIOUS ENVIRONMENTS

The exercise intensity and environmental conditions determine the extent to which dehydration causes hyperthermia during exercise and the extent to which fluid replacement can prevent the hyperthermia. When an individual exercises at a moderate intensity, e.g., 60-70% VO2max, in a warm/hot environment (20-35o C) with moderate humidity (<50% rh), heat is dissipated primarily by evaporative heat loss. This heat dissipation is impaired by dehydration, which decreases skin blood flow and sweating rate. In these environments, % loss of body weight due to dehydration causes core temperature to increase by about 0.15-0.30o C (Coyle & Montain, 1993). However, during exercise m a cool environment (0-10o C), dehydration appears to cause a relatively small degree of hyperthermia, probably because convective heat loss is sufficiently large to compensate for reduced skin blood flow and reduced evaporation of sweat.

Body core temperature is the balance between heat production and heat dissipation, and fluid replacement has its limitations if this balance is skewed. For example, in very hot and humid environments in which heat dissipation by evaporation and convection is minimal, fluid replacement will reduce cardiovascular stress and may improve performance, but it will have little effect on body temperature. Likewise, when the exercise intensity is great enough to cause a very high rate of heat production, it will not be possible for even well-hydrated people to increase heat dissipation enough to prevent excessive hyperthermia. In these situations, the only safe option is for individuals to reduce their heat production by lowering exercise intensity.



Figure 2. The influence of dehydration, as assessed by the percent reduction in body weight after 2 h of exercise, on the change in rectal temperature, cardiac output, and heart rate. (Reprinted with permission from Coyle & Montain 1992b).


TIMING OF FLUID REPLACEMENT DURING EXERCISE

Is there a time interval during prolonged exercise that is most advantageous for fluid replacement? Should one drink early in exercise, throughout exercise, or wait until near the end of the exercise? In an attempt to answer these questions, we studied cyclists who drank about 1 L of fluid at various times during 140 min of exercise (Montain & Coyle, 1993). They drank after either O, 40, or 80 min of exercise or drank the 1 L intermittently throughout exercise. In all cases, they incurred the same amount of dehydration after 140 min, and they were not different in any of their cardiovascular or THERMOREGULATORY responses. During the 40 min period immediately after drinking fluid, regardless of the time of drinking, the subjects stabilized their heart rates and core temperatures. During the periods without fluid ingestion, there was progressive hyperthermia and increased cardiovascular strain. These observations suggest that the volume of fluid ingested is most important, and the timing of ingestion is secondary.


Individual Trial and Error

Although we generally recommend that people drink large volumes of fluid and attempt to totally offset dehydration, we realize that individuals differ tremendously in their rates of gastric emptying and, there-fore, in their tolerances of large fluid volumes. Each person must devise an individualized drinking schedule that appears optimal and should become accustomed to this schedule during practice (Rehrer et al., 1989 ).

increases in body core temperature, heart rate, and ratings of the perceived difficulty of exercise. This same phenomenon probably also applies to running and argues against the notion that a certain amount of dehydration (e.g., up to 3% of body weight) is permissible and without cardiovascular consequences (Noakes et al., 1991 a). However, runners generally drink only 500 mL/h and thus allow themselves to become dehydrated at rates of 500-1,000 mL/h. Runners must compare the benefits of drinking large volumes of fluid during competition, i.e., the physiological improvements and the likely improvement in running speed during the late stages of the race, with the drawbacks of having to slow down while drinking and while suffering gastrointestinal discomfort. If the primary goal is safety, which means minimizing hyperthermia, there is no question that the runner should attempt to match the rate of drinking to the rate of dehydration.




SUMMARY

Ingestion of approximately 30-60 g of carbohydrate during each hour of exercise will generally be sufficient to maintain high rates of oxidation of blood glucose late in exercise and to delay fatigue. Because the average rates of gastric emptying and intestinal absorption exceed 1,250 mL/h for water and for solutions containing up to 8% carbohydrate, exercising sports competitors can be supplemented with both carbohydrate and fluids at relatively high rates.

When cyclists exercise at competitive intensities for 2 h in the heat with sweat rates of 1,400 mL/h, it is clear that the closer that fluid consumption matches sweating rate (at least up to 80% of sweating rate), the better. When fluid consumption is inadequate, increasing dehydration directly impairs stroke volume, cardiac output, and skin blood flow, resulting in progressive increases in body core temperature, heart rate, and ratings of the perceived difficulty of exercise. This same phenomenon probably also applies to running and argues against the notion that a certain amount of dehydration (e.g., up to 3% of body weight) is permissible and without cardiovascular consequences (Noakes et al., 1991a). However, runners generally drink only 500 mL/h and thus allow themselves to become dehydrated at rates of 500-1,000 mL/h. Runners must compare the benefits of drinking large volumes of fluid during competition, i.e., the physiological improvements and the likely improvement in running speed during the late stages in the race, with the drawbacks of having to slow down while drinking and while suffering gastrointestinal discomfort. If the primary goal is safety, which means minimizing hypothermia, there is no question that the runner should attempt to match the rate of drinking to the rate of dehydration.



References

Adolph, E.E Blood changes in dehydration. In: Physiology of Man in the Desert. New York: Interscience Publ., Inc., 1947, pp. 160-171.

Armstrong, L.E., R.W. Hubbard, EC. Szlyk, W.T. Matthew, and I.V. Sils. Voluntary dehydration and electrolyte losses during prolonged exercise in the heat. Aviat. Space Environ. Med. 56: 765-770, 1985.

Below, ER., R. Mora-Rodriguez, J. Gonzalez-Alonso, and E. E Coyle. Fluid and carbohydrate ingestion independently improve performance during 1 H of intense exercise. Med. Sci. Sports Exerc. (In press).

Bean, W.B., and L.W. Eichna. Performance in relation to environmental temperature. Reactions of normal young men to simuulated desert environment. Fed. Proc. 2: 144-158, 1943.

Coggan, A.R., and E.E Coyle. Carbohydrate ingestion during prolonged exercise: effects on metabolism and performance. Exerc. Sports Sci. Rev. 19: 1-40, 1991.

Costill, D.L., W.E Kammer, and A. Fisher. Fluid ingestion during distance running. Arch. Environ. Health 21: 520-525, 1970.

Coyle, E.E, A.R. Coggan, M.K. Hemmert, and J.L. Ivy. Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate. J. Appl. Physiol. 61: 165-172, 1986.

Coyle, E.E, and S.J. Montain. Carbohydrate and fluid ingestion during exercise: Are there trade-offs? Med. Sci. Sports Exerc. 24: 671-678, 1992a. Coyle, E.E, and S.J. Montain. Benefits of fluid replacement with carbohydrate during exercise. Med. Sci. Sports Exerc. 24: $324-$330, 1992b.

Coyle, E.E, and S.J. Montain. Thermal and cardiovascular responses to fluid replacement during exercise. In: C.V. Gisolfi and D.R. Lamb (eds.) Perspectives in Exercise Science and Sports Medicine. Vol 6: Exercise, Heat, and Thermoregulation. Carmel, IN: Brown & Benchmark, 1993, pp. 179-224.

Eichna, L.W., W.B. Bean, W.E Ashe, and N. Nelson. Performance in relation to environmental temperature. Bull. Johns Hopkins Hosp. 76: 25-58, 1945.

Houmard, J.A., EC. Egan, R. Anderson, ED. Neufer, T.C. Chenier, and R.G. Israel. Gastric emptying during 1 h of cycling and running at 75% VO2max. Med. Sci. Sports Exerc. 23: 320-325, 1991.

Gonzalez-Alonso, J, R. Mora-Rodriquez, ER. Below, and E.E Coyle. Reductions in cardiac output, mean blood pressure and skin vascular conductance with dehydration are reversed when venous return is increased. Med. Sci. Sports Exerc. 26: S 163, 1994.

Mitchell J.B., D.L. Costill, J.A. Houmard, M.G. Flynn, W.J. Fink, and J.D.Beltz. Effects of carbohydrate ingestion on gastric emptying and exercise perfor-mance. Med. Sci. Sports Exerc. 20: 110-115, 1988.

Mitchell J.B., D.L. Costill, J.A. Houmard, W.J Fink, R.A. Robergs, and J.A. Davis. Gastric emptying influence of prolonged exercise and carbohydrate concen-tration. Med. Sci. Sports Exerc. 21:269-274, 1989.

Mitchell J.B., and K.W. Voss. The influence of volume on gastric emptying and fluid balance during prolonged exercise. Med. Sci. Sports Exerc. 23: 314-319, 1991.

Montain S.J., and E.E Coyle. Fluid ingestion during exercise increases skin blood flow independent of increases in blood volume. J. Appl. Physiol. 73: 903-910, 1992a.

Montain S.J., and E.E Coyle. The influence of graded dehydration on hyperthermia and cardiovascular drift during exercise. J. Appl. Physiol. 73:1340-1350, 1992b.

Montain S.J., and E.E Coyle. Influence of the timing of fluid ingestion on temperature regulation during exercise. J. Appl. Physiol. 75: 688-695, 1993.

Murray, R, D.E. Eddy, T.W. Murray, J.G. Seifert, G.L. Paul, and G.A. Halaby. The effect of fluid and carbohydrate feedings during intermittent cycling exercise. Med. Sci. Sports Exerc. 19: 597-604, 1987.

Murray, R., G.L. Paul, J.G. Seifert, and D.E. Eddy. Responses to varying rates of carbohydrate ingestion during exercise. Med. Sci. Sports Exerc. 23: 713-718, 1991.

Noakes, T.D., K.H. Myburgh, J. Du Plessia, L. Lang, M. Lambert, C. Van Der Riet, and R. Schall. Metabolic rate, not percent dehydration, predicts rectal tem-perature in marathon runners. Med. Sci. Sports Exerc. 23: 443-449, 1991a.

Noakes, T.D., N.J. Rehrer, and R.J. Maughan. The importance of volume in regulating gastric emptying. Med. Sci. Sports Exerc. 23: 307-313, 1991b. Noakes, T.D. Fluid replacement during exercise. Exerc. Sports Sci. Rev. 21: 297-330, 1993.

Pitts, G.C., R.E. Johnson, and EC. Consolazio. Work in the heat as affected by intake of water, salt and glucose. Am. J. Physiol. 142: 253-259, 1944.

Rehrer, N.J., E. Beckets, E Brouns, E Ten Hoor, and W.H.M. Saris. Exercise and training effects on gastric emptying of carbohydrate beverages. Med. Sci. Sports Exerc. 21: 540-549, 1989.

Rehrer, N.J., E.J. Beckers, F. Brouns, ETen Hoor, and W.H.M. Saris. Effects of dehydration on gastric emptying and gastrointestinal distress while running. Med. Sci. Sports Exerc. 22: 790-795, 1990.

Rehrer, N.J., E Brouns, E. Beck

Edited by tjtryon 2007-07-27 7:18 AM

Wow! Great info TJ. Thanks. You're either one very intelligent guy when it comes to this stuff or you did a lot of cutting and pasting. It'll take me a bit to digest all this stuff, but I'm sure I'll learn alot through experience. Thanks again for the info. I'm sure the others in the group will find it helpful too.

Neither... I'm currently working on what I need to know to get my coaching certification, and I am working on the nutrition side of it as well - I retain what I read very well. Additionally, I have been doing at least 1 of the 3 sports since the 70's - so there is some experience there as to what works for me.

Glad I could be helpful.

Hey everyone!!

I'm just wondering how everyone's training is going?? I also have a question for TJ.

I've been training pretty hard and haven't taken a day off in about a week and a half. I find swimming relaxes me and doesnt really affect my recovery between run/bike workouts. Is it passable to do a swim workout on my days off? Swimming is the LEAST of my worries and I really am just using it as a break from running and/or biking.

Any ideas on the matter??
Thanks
Derek

The simple answer is that a rest day from training is really just that. That means you need to rest - no training... It really helps your body heal and get faster...

If life were only that simple, right? I find the best way to determine if you are training too hard is to listen to your heart - check your pulse rate in the AM before you get out of bed.

You do have a heart rate monitor right? If not, this should be high on your priority list.

My HRM sits on my night stand. Check your heart rate, laying in bed, before you even sit up in the morning. If your heart rate is 5-10 beats above your normal rate, you may need to take the day off. Additionally, if it is 5-10 beats below, you could be getting ill.

Technology training at it's greatest...

If you have been training hard, take at least 1 day per week off as a rest day. No swimming, no running, no cycling, no weights. Eat well - hell, you've been working hard - eat whatever you want, rest, and play catch up on family, spouse, girlfriend, lawn time.

It will make you faster in the long run.


Edited by tjtryon 2007-07-31 12:30 PM

Derek:

I've been pretty pleased with my training, considering I've been doing it only since the beginning of May. I'm finally at the point where I enjoy it. I always take at least 1 rest day during the week, both for the physical and mental aspects. I know it's tempting sometimes to keep working out, especially when you feel good. But I know that I have to take it easy some days or else I'll run the risk of over-training for my current ability level or worse...get injured. Keep up the good work!

Wow thanks for the speedy responses guys!!

Unfortunately TJ, I dont have a heart rate monitor, and with all the other stuff I've had to invest in for my cycling/running lately, I dont really have the money either! I wish I did, because I've been told many times that they are extremely helpful!! When I was still swimming we used them all the time, but I never actually invested in one!

Regardless, I'm taking today off to just relax!! I guess I just keep convincing myself that I dont need a day off, even when I probably do!

I hope all your training is going well guys!! I'll check around your training logs


Talk to you soon!
Derek

Who is racing this weekend? Let everyone know what you're doing and what your goals are. I'm doing my 2nd Sprint Triathlon in Laporte, IN (1/4mi, 12.4mi, 3.3mi). My goals:

1. Have Fun
2. Finish with smile
3. Time of 1:23 or better

Good luck to everyone!

Sorry I haven't checked in a lot lately. It seems I just get so busy at times that some things get neglected. By the way, I also take one rest day a week. I do a double on Wednesday, biking or swimming in the morning, and then running speed or hill work in the evening, so I usually take Tuesday off to rest up so I am fresher for the next day.

I am also racing this weekend. This is a short Sprint, .25 mile swim/10 mile bike/3.1 mile run. My goals:

1) Finish with a smile
2) Don't be last in my age group
3) Swim in less than 10 minutes/Bike in less than 35 minutes/run in less than 35 minutes, get faster at my transitions, so break 1:25:00 for the event.
4) Eat and Drink Beer!

Jerry

Good luck. And remember the most important goal....Have Fun!

Good luck Dan and Jerry!

You guys will do awesome I'm sure!! And yes having fun/smiling is the most important part!
Kill those goal times
I'll be watching for the race reports!

And nix on the Good luck
And instead, BREAK A LEG!

Ok, I'm having a bit of a problem guys.

So I went for a run on Wednesday, with my goal being 16km (10 miles), I only ended up doing 13.5km (about 8 miles). I know I'm in good shape and I have been running quite a bit lately, without any problems (injuries etc.).

At about the 11km mark during my run, I got this intense pain in my right lower leg. I thought it might be shin splints, but it didnt feel like it was on the shin itself. I also was getting pain on the inside of my Quad just above my left knee. This wasnt normal pain, and I have NEVER had this before. I did have an ITB problem that started about 2 months ago, but went to tons of physio and really backed off the running for quite a while, and it hasnt bothered me since, but now all of a sudden I have this (definitely not soreness) fairly excruciating pain.

Does anyone have any experience with this, or know what could be causing this?
By the way, I did buy new shoes over a month and a half ago, but they have caused no problems, and just helped to ease up my ITB problem due to the massive cushion (Adistar Cushion 6 model).

Any help would be greately appreciated!
THanks a ton
Derek
PS: I have a running clinic tonight, but I'm kinda worried about it

If this is the first time you've felt the pain, it could be any number of things from simply tweaking it or stepping wrong on the run to a more serious scenario like a strain. Could also be something from your weekend hiking trip? My leg problems this summer have been in my calves and only occasionally when I havent drunk enough water or milk. Also, I'm running far less than you right now so I'm not putting as much stress on my legs. How did the legs feel yesterday and today? If the pain is still there, I'd recommend either skipping the running clinic or going very easy. If the pain has seemed to subside over the last couple of days, it could have simply been from the pounding of a long run. Take it easy tonight. Make sure you're warming up and stretching out completely for your runs, too.

Thanks for the quick reply Dan!

I'm thinking it might be a result of the hike as well, as I was carrying a 60 pound(ish) frame pack, going downhill all the way back. It's very possible that's where the pain is stemming from. I plan on taking it very easy tonight, I think I will still go though.

Yesterday my legs felt awesome for my 45km ride, so I know that it's not affecting any muscles used in cycling, which is great, just in case I need to really lay off the running.

I have been trying to stretch a ton more, and I think it's worked great up until Wednesday, but I think it may have just been trying to do too much after a super strenuous weekend of hiking.

Who knows!!!!
Thanks a ton for the feedback!
Derek