Amateur marathon runners
(Reuters Health) - Amateur marathon runners who run less than 40 miles per week during training often show signs of cardiac dysfunction after the race and some of these abnormalities may persist for up to a month after they cross the finish line, a study shows. "Running less than 40 miles per week prior to running a marathon leads to temporary heart muscle weakness and increased pressure in the lung arteries," Dr. Malissa J. Wood told Reuters Health. "Individuals who consistently ran greater than 45 miles per week showed no such signs of damage after completing the marathon."
The findings are based on a study of 20 amateur athletes who ran the 2003 Boston Marathon and underwent echocardiography (ultrasound imaging of the heart) prior to, immediately after, and about one month after running the 26-mile race.
The number of people participating in endurance sports has increased in the past decade, Wood, from Massachusetts General Hospital and Harvard Medical School, Boston and colleagues note in a their study, published in the European Heart Journal.
In the U.S. alone, nearly 480,000 runners completed a marathon in 2001. And while the benefits of moderate exercise on the heart are well established, the effects of more prolonged exertion are less clear. Some studies have suggested that cardiac dysfunction or "cardiac fatigue" occurs during prolonged exercise.
The series of echocardiographs obtained for the 20 amateur marathoners demonstrated "attenuation" of heart function after the race.
There was evidence of abnormalities in both systolic function (the heart's pumping ability) and diastolic function (the heart's ability to relax during beats).
All of the systolic abnormalities normalized fairly quickly, but the diastolic abnormalities persisted for up to one month after the race, indicating an inherent alteration in the heart's ability to relax, the authors note.
Wood and colleagues emphasize that their results do not pertain to elite athletes; "our group consisted of runners who ran on average less than 40 miles a week during training, a level that is most consistent with the 'average' marathon runner."
Their study also does not address whether this transient dysfunction damages the heart or if there are any long-term cardiac consequences.SOURCE: European Heart Journal, May 2006.
Publish Date: June 15, 2006
Why distance runners have higher rates of sudden cardiac death than other athletes
Also consider the story of marathoner, Jim Fixx, who preached that long-duration cardiovascular endurance training was the best method for achieving optimal health. He practiced what he preached, right up to the moment he dropped dead of a heart attack - while running.
Every year very well-conditioned long-distance runners suffer sudden cardiac death. Distance runners have higher rates of sudden cardiac death than other athletes do. Modern marathons have emergency stations specifically equipped to handle the abnormal heart rhythms, heart attacks, and other cardiac emergencies that can be expected to occur. This increased risk appears regardless of culture or diet.
Long-distance running has a detrimental effect on the health of your blood fats. Scientists in Barcelona, Spain, examined the blood of long-distance runners and found that after a workout they experienced an increase in both the blood levels of and the oxidation of LDL cholesterol and triglycerides.
Worse yet, a report in the American Journal of Cardiology found that distance running disrupted the balance of blood thinners and thickeners, elevating clotting levels and inflammatory factors. These changes are signs of heart distress, not a heart that's becoming stronger after exercise.
Using a Heart Rate Monitor
Many coaches say heart rate monitors have revolutionized the endurance sport coaching business. HRMS are responsible for a new accuracy and specificity in coach/athlete communications that'�s not possible by simply describing workouts in terms of RPE (relative perceived exertion) or 'feel.' But you might say, "I've always trained by feel and it�s worked well for me all these years." I did quite well without a heart rate monitor for the first 15 years of my athletic career as well. But now that I use one for most workouts and occasionally in races, I have more control over the results of my training and racing. By tracking heart rates I've seen during specific workouts, I have reference points for over-training, under-training, and the quality of my hard efforts. I�d like to think that my ability to sense I�m doing just the right thing in training is infallible, but in reality it�s not. For example, sometimes when I have that euphoric feeling after a great race I feel indestructible. I know I�m supposed to do some easy recovery workouts, but what I really want is to keep that feeling going�so I hammer! Not smart. Fortunately, I�m wearing my HRM and I know I�m not supposed to go above a heart rate of XXX on recovery days. I back off so I don�t 'leave' my next fantastic race in training. At other times, I may be doing a hard tempo or time trial effort, but I just can�t get going. I look down at my HRM and it�s 10 beats too low for my relative perceived effort (RPE) level. In this case it usually means I�m over-trained and need a break. Heart Rate Monitors
Determine Your Maximum Heart Rate This is the critical first step so that you can calculate percentages of your maximum heart rate as a guide. Not all athletes see their maximum HR in training or racing (it hurts too much), so initially there may some guesswork involved in your calculations. Here�s the rule for determining your maximum HR if you fit the average profile: For men subtract your age from 220 beats per minute, for women subtract your age from 227 beats per minute. This works well for about 40-50% of the athletic population, but the values for the rest can vary by as much as 10 beats on the low side or 20+ beats on the high side. Most athletes only get within 5 beats of their maximum while sprinting at the end of a short race. Some may get closer to their max when doing longish interval repeats on the track. The highest HR I�ve seen occurred while doing half-mile repeats in 100+ degree heat at a New Mexico training camp. Yes, that was nuts; do as I say, not as I do ;-). Anyway, it may take a few track workouts or races with the HRM before you can determine your max HR. If the formulas above based on the mean for age and gender don�t work for you, I recommend adding 2 to 5 beats to the highest HR you�ve seen, for an estimated maximum. Judging by the formula, your max HR should drop by 1 beat every year. I doubt this is true for endurance athletes over thirty who've been in continuous training. For us I think the drop is only 1/2 of a beat per year, so using the formula you may need to subtract 1/2 a beat for each year you've done aerobic training over age 30 instead of 1 beat.
Determining Heart Rate Ranges (percentages of max HR) This is fairly easy once you've determined your maximum heart rate. There are two methods: 1) A range based on zero (dead) to your max HR. 2) A range based resting HR to max HR. The latter was named the "Karvonen" method after a Scandinavian physiologist; it creates narrower ranges and is preferred by endurance coaches. The former method is often used at fitness facilities. Here�s how to calculate your percentage of maximum heart rate following the Karvonen method: We�ve already found what we believe to be our maximum HR, now we need to find our resting heart rate. The number I use is the lowest HR I�ve ever counted (or seen on the HRM) while sitting very quietly totally relaxed. I consistently find my lowest HR early in the morning, lying still in bed upon awakening.
To find the ranges in 10% increments without a calculator: Subtract the minimum HR from maximum. Divide the number by 10, then add 10% increments as needed. Here�s an example: 190 (max HR) minus 50 (resting HR), 190-50 = 140. Divide 140 by 10 (140/10 = 14) for 14 beats for each 10%. To figure 70% of your maximum heart rate multiply 14 x 3 to get 42 beats per minute, subtract 42 from 190 and get 148 for 70% of max HR.
To find ranges with a calculator use this formula: Max HR - min HR x percent as a decimal + min HR. For example to find 75% of max: 190 - 50 = 140 x .75 = 105 + 50 = 155.
Make sure you know which HR percentage method a coach is referring to when discussing training plans.
Now that you have a formula to find these percentages, how do they fit into a training plan?
Heart Rate Percentages and Training Effect Each heart rate range has a distinct effect for your training. I�ll describe what pulse range is appropriate for each type of workout for runs.
Note: The ranges will be 5 to 8% lower for equivalent RPE for cycling.
65% to 70% This is an effort level considered appropriate for very easy run training and recovery days after tough training or race efforts.
70% to 75% This is the range for maximum aerobic training benefit, and moderate "base" training that is not especially stressful to the body. This range is also the best to develop your metabolism�s fat burning capability for distance races like half to full Ironman distance. The majority of your training should be done in this range.
75% to 80% This is mild tempo training that helps to build your muscular/skeletal foundation for the rigors of racing. This range is especially valuable during the early pre-season phase when you need to 'toughen-up' in preparation for higher intensity training and racing.
85% This is considered fast tempo training. It�s not quite race pace (except for very long races) but it simulates race efforts without the need for as much recovery afterwards. This intensity should be performed as late pre-season training, and as a substitute for races when there are none available.
85% to 95% This is the race effort range. During a PR 5k race effort, you may find yourself holding 95% for the second half of the race. For a fast 10k you�ll probably be in the 90% to 95% range for your best effort. Also, when you do speedwork on the track you should expect to see a heart rate at or above 90% of max for much of the workout.
Some Finer Points of Training with a HRM Your heart�s response to exercise is directly proportional to the amount of muscle mass being used for the activity. In other words, a sport that involves more muscle to propel your body, will demand higher heart rates. This is why observed maximum heart rates while running are typically 8 to 10 beats higher than cycling. While running or cycling at identical perceived effort levels which are below maximum, the same 8 to 10 beat difference will apply.
Most HRMs have a lag time of a couple seconds between receiving the signal and the number you see, which is averaged within the unit. There�s also a lag time (heart rate drift) for your heart�s response to stress during warm-up and race starts. If you sprint-out in a race hoping to see your target HR during the first quarter mile, you could be in serious trouble later. This applies to any training or racing outing, since your pulse will gradually creep up (drift) as you warm-up, and also as fatigue sets in. When describing a certain effort level by percentage of max HR, the number is meant to be an average over the duration of the workout. A pulse 5 to 10 beats higher is acceptable on tough hills as long as it drops back down afterwards. Also, when attempting an even or negative split for a training outing or race, expect to see higher numbers for the second half of the workout (again, due to HR drift). If I want to maintain an average of 150 bpm over my entire workout - with even pacing, I�ll stay in the high 140s for the first half and low 150s for the second half.
Interference from other HRM units is a possibility when other HRMs are nearby. When you�re training or racing with others and you see a heart rate value that just can�t be right, consider the interference possibility. It can happen in situations where you're very close to another athlete, or when the battery in their transmitter is stronger (perhaps fresher) than yours. You can also get a false reading in magnetic fields such as running under power lines.
I recommend using your heart rate monitor along with your own finely tuned sense of perceived effort to assess your workouts and races. When you learn to combine the information from both sources effectively, the knowledge gained will allow you to maximize your athletic time and energy.
Balke 15 Minute Run This is a very simple test to predict your VO2max. What equipment do you need? A stop watch and a 400m running track.
After warming up run for 15 minutes continuously. The idea is that you maintain a steady pace throughout the race. The distance you cover is converted into a predicted VO2max using the following table...
Cooper 12 Minute Run
This is another endurance test you can simply use to predict your VO2max. Again you only require a stopwatch and a 400m track.
Run or walk continuously for 12 minutes. Again try to maintain a constant pace throughout. Note the total distance covered and use one of the following formulas to predict your VO2max...
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