A stunning set of three female porecelain figurines from the western coastal Chinese Province of Zhejiang. The figurines shows men in traditional Chinese dress. The Chinese blue paintings on a white background make this a stunning addition to any room.
This is what people don’t understand: obesity is a symptom of poverty. It’s not a lifestyle choice where people are just eating and not exercising. It’s because kids – and this is the problem with school lunch right now – are getting sugar, fat, empty calories – lots of calories – but no nutrition.
Tom Colicchio
What is lactate?
During very intense exercise, the development of the “burn” in muscles usually is referred to as lactic acidosis. This theory is still taught in many physiology courses throughout the world. To set the record straight, recent research is disputing this popular interpretation. Looking briefly at some basic physiology will help to explain one of the primary causes of muscle fatigue. During the demands of high-intensity exercise, the cells use a substantial amount of glucose and glycogen (stored glucose) for energy. The biproduct of cellular glucose breakdown is lactate. This increase in lactate coincides with an increase in blood and muscle acidity (hydrogen ions), which is one of the culprits of muscular fatigue; therefore, even though lactate is not responsible for the actual burn, it is an excellent indirect method of determining the level of cellular fatigue using lactate testing.
What is the lactate threshold? Why is it beneficial? How is it measured?
At rest and under steady-state exercise conditions, there is a delicate balance between the amount of blood lactate produced and the amount of blood lactate removed (metabolized) in the body. The lactate threshold is the point above which there begins an abrupt increase in lactate levels caused by an increase in exercise intensity-that is, the point in which blood lactate accumulation exceeds removal.
Lactate threshold testing is considered by sports scientists to be one of the single most important measures of success in endurance-related activities. Determining and correctly using lactate testing data can help athletes to train and compete at the right intensities to avoid premature fatigue and/or overtraining.
The lactate threshold can be measured accurately using a reliable lactate analyzer. Lactate devices today have become more miniaturized and can be conveniently transported to the field or pool for onsite testing. To test for the lactate threshold, an athlete will be subjected to a graded exercise test either in the laboratory (bike, treadmill), on the field, or in the pool. Each endurance exercise stage lasts approximately 4 minutes, and each successive step increases in intensity challenging the athlete’s energy systems. Blood lactate draws, using a finger stick, are taken at the end of each stage and evaluated and recorded on the lactate analyzer. The lactate values from each stage are plotted on a graph that corresponds to the athlete’s workload. Graph analysis clearly demonstrates the point at which there is a significant increase in lactate levels (lactate threshold).
Training correctly, in conjunction with regular lactate testing, can have a significant positive effect on an athlete’s lactate threshold and performance. The pre-training and post-training program can be seen in the changes of the deflection points. The data demonstrate that this athlete has improved by approximately 50 watts of power in 4 months, a significant improvement.
What is the better method of determining my exercise training heart rate zone?
Heart rate monitoring is the most common method used by athletes to gauge their intensity of exercise. Heart rate reflects the amount of work that the heart is performing for a particular workload. During exercise, the heart responds to increased stress by beating faster to provide necessary oxygen-rich blood to the exercising muscles. There is a lineal relationship between the workload and heart rate; as workload increases, so does heart rate. Heart rate tops out when the body achieves volitional fatigue (exhaustion) and is relatively reliable from one workout to next. This maximum heart rate value is often referred to as HRmax.
Heart rate is usually measured at the radial pulse (wrist) or carotid artery (neck). Resting heart rate is the heart rate of an athlete while at rest and varies significantly between athletes. The variability is dependent on an athlete’s genetics, age, fitness level, and time of day.
1. Genetics: Some athletes are born with either a higher or lower resting heart rate.
2. Age: Resting heart rate declines with age and drops approximately one beat per minute, per year starting around the age of 15 years.
3. Fitness: Resting heart rate generally decreases as cardio respiratory fitness increases. The average resting heart rate is usually between 60 to 70 beats per minute. A well-conditioned endurance athlete such as a marathon runner can have a resting heart rate as low as 30 to 40 beats per minute. Conversely, a sedentary, unfit individual can have a resting heart rate of as much as 90 to 100 beats per minute.
4. Time of day: Resting heart rate increases throughout the day-it is lower in the morning and higher in the late afternoon and evening. This increase is influenced by the body’s circadian rhythm (body clock) and the hormonal and biochemical changes that occur over 24 hours.
Four methods for determining heart rate training zones are available to athletes. Some methods are more reliable than others. The one that an athlete selects will depend on how serious an athlete is about his or her training and its monitoring.
The four methods include the following:
1. VO2 max testing: This is the single most accurate and reliable method of testing an athlete’s heart rate responses to changing workloads. Unfortunately, this method may be out of reach (cost, availability) for most athletes.
2. 220 – age (age in years): This is a rough and ready formula that is used to determine the heart rate maximum. It is easy and convenient to use, but it has limitations. The major limitation is that it does not take into consideration the tremendous variability in an individual athlete’s heart rates.
3. 208 – (0.7 × age) (age in years): This more recent equation takes into account the inevitable decline in heart rate with age.
4. Karvonen formula, training heart rate = (heart rate maximum – resting heart rate) × intensity + resting heart rate: Next to VO2 max testing, the Karvonen formula is probably the single best predictor of heart rate intensity. This method is often referred to as the heart rate reserve method; as it takes into account an athlete’s resting heart rate. Earlier, it was mentioned that there was significant variability between individual athletes’ resting heart rates.
Athletes must establish an accurate resting heart rate by taking their pulse on awakening in the morning. The pulse should be taken over a 3-day period to ensure consistency; the average of the 3 days should then be calculated.
Case Study
Kelly is a 30-year-old runner who is preparing to run the Boston Marathon. She has been training regularly for 5 months and is getting close to the competition. Kelly wants to run the marathon at 70% of her heart rate maximum, and she is going to use all three formulas to see what provides her with the best results.
1. Heart rate maximum = 220 – age 220 – 30 = 190 beats per minute 70% of heart rate maximum = 190 × 0.7 (intensity) = 133 beats per minute
Using this method, Kelly would want to compete at a constant HR of 133 beats per minute.
2. Heart rate maximum = 208 – (0.7 × age) 208 – (0.7 × 30) 208 – 21 = 187 beats per minute 70% of heart rate maximum = 187 × 0.7 = 130 beats per minute
Using this more accurate formula, Kelly would want to compete at a constant heart rate of 130 beats per minute.
3. Karvonen formula: training heart rate = (heart rate maximum – resting heart rate) × intensity + resting heart rate Kelly calculated her resting heart rate to be 50 beats per minute (this was calculated by taking an average
3-day heart rate first thing in the morning).
Heart rate maximum is calculated by using the 220 – age equation: 220 – 30 = 190 beats per minute. Therefore, training heart rate = (heart rate maximum – resting heart rate) × intensity + resting heart rate Training heart rate = (190 – 50) × 0.7 + 50 140 × 0.7 + 50 = 98 + 50 = 148 beats per minute By comparing the various formulas for determining exercise heart rate at 70% intensity, there is evidently a significant disparity between the various methods: 133, 130, and 148 beats per minute. An athlete should experiment with each heart rate method to determine which formula is better suited for his or her level of intensity. If an athlete is familiar and confident in the use of the RPE scale, he or she should compare each heart rate outcome with a 12–13 (somewhat hard) for a reliable comparison. If one particular heart rate generates a 10–11 (fairly light) on the RPE scale, then an athlete should increase to the next higher heart rate.
Term:
Lactic acidosis – A condition in which there is a significant accumulation of hydrogen ions in the blood and tissue, leading to muscle acidification.
Lactate threshold testing – Considered by sports scientists to be one of the single most important markers of success in endurance related activities.
During the demands of high-intensity exercise, the cells use a substantial amount of glucose and glycogen (stored glucose) for energy.
An athlete should experiment with each heart rate method to determine which formula is better suited for his or her level of intensity.
