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Lactivity

From:

Lactivity Sport and Lactate
Dr L Schwarz & M Schwarz
Institute für Sport und Leistungsmedizin
Universität des Saarlandes

 

SPORTS MEDICINE PRINCIPLES 

Training needs to be personalized to make sure it is contributing to fitness and health.  

All physical activity needs a supply of energy. This energy comes from the body’s breakdown of carbohydrates, fats and proteins. The most is carbohydrates, which can be broken down in two ways: aerobic and anaerobic. 

Aerobic energy occurs when the cardiovascular system is able to carry enough oxygen to the muscles. The by-products of aerobic energy production are carbon dioxide and water, which are non-toxic to the body. This is the clean method of energy production. 

If the rate of exercise goes above the ability of the body to supply the level of oxygen required (and this is dependant on the individual’s level of training) then the body uses the other method of making energy; anaerobic. This method has the drawback of making lactate as a waste product. Lactate over a certain level reduces and eventually stops muscular activity.  

A small amount of lactate can be removed from the muscles by the blood system. But if training continues too long or the intensity is too high, lactate begins to build up. 

How each person uses the two energy production methods depends on genetic factors and their level of training. 

Lactate in performance analysis

By measuring lactic, you can see a person’s performance capacity. Sports medicine does this by exercising at a low level and increasing this level until the person is exhausted and unable to continue. The lactate and heart rate are measured at the beginning, during the workout and during recovery. This gives the lactate/workload curve.  

Lactate increases slowly at low workloads, as there is sufficient oxygen available to supply the muscles.  

However once the workload gets to the level where anaerobic energy is required the level of lactate increases quickly. A small increase in workload brings an over proportional increase in lactate. ‘The transition from the initially flat lactate curve to the steep region is called the anaerobic threshold. It defines the endurance limit and is the highest workload at which equilibrium between lactate production and lactate elimination is still maintained’. Is it the same for everyone. However the person who is trained for endurance will be able to perform a workload purely aerobically, while an untrained or less trained person would already be forming increasing quantities of lactate.  

‘…the use of lactate measurements to evaluate performance capacity can be considered; what price (how much lactate) must be paid for a particular performance (e.g. running speed)? 

Endurance is the major aim of training. The objective of training guidance is to quantify the workload so that the performance and health effects of training are optimised i.e. enabling as much energy as possible to be provided by the aerobic path. 

‘Endurance training can set in motion natural protection mechanisms against cardiovascular diseases. After even a few weeks of training the cardiovascular function and the metabolism become more economical. The trained heart switches over to a more economical mode, in which it beats less often for the same output. The economy is observed both at rest and during everyday activities and leads to a reduction in oxygen demand. At the same time the release of stress hormones such as adrenaline, which speed up the sluggish heart during everyday stress situations, are reduced. The right amount of exercise thus leads to a lasting reduction of the load on the heart.’ 

‘A second important aspect is the effect on risk-factors. Many studies have shown that certain traits and modes of behaviour increase the risk of heart disease. These cardiovascular risk factors include elevated blood cholesterol levels, high blood pressure, smoking, overweight and lack of exercise.’ Exercising, combined with appropriate eating habits, can contribute to lowering cholesterol, blood pressure and body weight. As the cholesterol level is lowered the good HDL-cholesterol increases in respect to the bad LDL-cholesterol. Achieving the desirable benefits require the right workload. The two important indicators of this are the lactate concentration and the heart rate. Simultaneous lactate and heart rate measurements show if a person is exercising aerobically or anaerobically at the measured heart rate. The heart rate can be adjusted up or down depending on the lactate.’

 

APPLICATION OF LACTATE MEASUREMENTS IN PRACTICE

The modern lifestyle of poor eating habits and lack of exercise results in health problems.  

Endurance sports

Dynamic exercises that make demands on large muscle groups, such as running, cycling, swimming and rowing take first place. In running and rowing most of the muscles are in motion, in cycling only the legs, and in swimming mostly the arms. 

Overweight people, however, should consider an exercise where the body weight is carried by equipment, such as rowing or cycling. 

How often, how long and how hard should one train?

The ideal training frequency, duration and intensity depends on what you can already do and what you want to achieve.  

Frequency and duration

The health orientated person should engage in endurance training 3 times a week for 30-45 minutes at a time. The training effect is greater then with a 2 hour session each week or with 5-10 minutes each day.  

Training intensity

The workload should be sufficient to reach 60-70% of the max performance capacity. The correct intensity can only be found by heart rate and lactate measurements. 

Heart rate

  • Heart rate when running: 200 minus age
  • Heart rate when cycling: 180 minus age
  • Heart rate when swimming: 170 minus age

The pulse must be measured during or immediately after training. The numbers of beats is counted for only 10 seconds and the result is multiplied by 6. A pulse meter is more accurate as it allows the heart to be monitored exactly during exercise. 

Lactate

This can be measured using a small meter. 

‘Lactate levels higher than 4 mmol/l should be avoided to achieve optimal training and health benefits without overexertion. At higher workloads carbohydrates are used. Stimulation of fat metabolism, which is better from the viewpoint of health, occurs only during training at moderate intensity.’ 

Muscle training

Training provides not only a well functioning cardiovascular system, but also increased body strength, provided by strengthening the main and peripheral muscles. The types of strength training need to be considered: endurance training and muscle building.  

Lactate measurements, particularly for beginners, offer a sensible way of avoiding incorrect workloads and identifying the correct level. For advanced athletes occasional checks on the lactate and appropriate workload adjustment ensures optimisation of training.  

Training development when taking up endurance training

‘The untrained beginner can rarely exercise continuously for 30-45 minutes. What is needed is a development program, in which the duration and frequency of training sessions is adjusted to the baseline capacity and then increased step by step.’

Week of training                  1 & 2      3              4              5              6 

Frequency

(Sessions per week)               2         2            2-3            3               3 

Duration (minutes)                  5         5              6           8             10 

Warm up phase                     5          5             6             8              10 

Exertion                              10        15            20           25              30 

Cooling-off phase                   3          3             4             5               5 

Total time taken                   18        23            30           38             45

 

Initially the period of exertion should be short, leading up to continuous exertion over a period of weeks. 

During the first weeks it is a good idea to improve technique to a style which is economical and easy on the joints. 

In the first weeks exertion should be guided by heart rate. From the third week workload should be checked, and corrected, by measuring lactate. As training continues occasional checks of lactate monitor development of performance. Increasing performance gives a feeling of achievement, provides motivation and enjoyment of training. Enjoyment is essential.

Exercising in the high (hard) zone has a negative effect on the body.

The average person, without direction, trains at lactase 6 and above - that is, too intensely. One of the great rules of training is to learn to monitor your breathing pattern - by definition, if you lose control of your breathing pattern you have exceeded the anaerobic threshold.

Anaerobic breakdown of glucose rapidly uses up your glucose stores. It uses almost twenty times more glucose per unit of power produced - that means it is twenty times less efficient than the aerobic breakdown of glucose for energy. In summary: above lactase 4 you rapidly burn up lots of energy. It’s not sustainable -  and makes you feel terrible if you do it too often.

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