Endurance Training

What is the objective of endurance training?

Endurance training aims to develop energy production systems to meet the event's demands.

What are energy production systems?

Adenosine triphosphate (ATP) is a chemical compound that supplies muscular contraction energy. Actively contracting muscles obtain ATP from glucose stored in the bloodstream and the breakdown of glycogen stored in the muscles. Exercising for extended periods will require the complete oxidation of carbohydrates or free fatty acids in the mitochondria.

What types of endurance are there?

The types of endurance are aerobic endurance, anaerobic endurance, speed endurance and strength endurance. A sound basis of aerobic endurance is fundamental for all events.

Work conducted by Gastin (2001)^[1] provides estimates of anaerobic and aerobic energy contribution during selected periods of maximal exercise (95% effort).

Duration	% Aerobic	% Anaerobic
0-10 seconds	6	94
0-15 seconds	12	88
0-20 seconds	18	82
0-30 seconds	27	73
0-45 seconds	37	63
0-60 seconds	45	55
0-75 seconds	51	48
0-90 seconds	56	44
0-120 seconds	63	37
0-180 seconds	73	27
0-240 seconds	79	21

Aerobic Endurance

During aerobic (with oxygen) work, the body works at a level that the body's intake can meet the demands for oxygen and fuel. The only waste products formed are carbon dioxide and water removed by sweating and breathing.

Aerobic endurance can be sub-divided as follows:

Short aerobic - 2 minutes to 8 minutes (lactic/aerobic)
Medium aerobic - 8 minutes to 30 minutes (mainly aerobic)
Long aerobic - 30 minutes + (aerobic)

Aerobic endurance is developed using continuous and interval running.

Continuous duration runs to improve maximum oxygen uptake (VO₂max)
Interval training to improve the heart as a muscular pump

Aerobic threshold

The aerobic threshold, at which anaerobic energy pathways start to operate, is around 65% of maximum heart rate. This is approximately 40 beats slower than the anaerobic threshold. The aerobic thresholds of untrained males range from 35 to 65% VO₂ max^[2].

Anaerobic endurance

During anaerobic (without oxygen) work, involving maximum effort, the body works so hard that the demands for oxygen and fuel exceed the supply rate, and the muscles have to rely on the stored reserves of fuel. The muscles, being starved of oxygen, take the body into a state known as oxygen debt and lactic starts accumulating in the muscles. This point is known as the lactic threshold or anaerobic threshold, or the onset of blood lactate accumulation (OBLA). Activity will not be resumed until the lactic acid is removed and the oxygen debt is repaid.

The body can resume limited activity after a small proportion of the oxygen debt has been repaid. Since lactic acid isis produced, this pathway's correct term is lactic anaerobic energy pathway.

The alactic anaerobic pathway is when the body works anaerobically but without lactic acid production. This pathway depends on the fuel stored in the muscle, which lasts for approximately 4 seconds at maximum effort.

Anaerobic endurance can be sub-divided as follows:

Short anaerobic - less than 25 seconds (mainly alactic)
Medium anaerobic - 25 seconds to 60 seconds (mainly lactic)
Long anaerobic - 60 seconds to 120 seconds (lactic +aerobic)

Anaerobic endurance can be developed by using repetition methods of high-intensity work with limited recovery.

Aerobic endurance training results in reduced body fat, increased maximal oxygen uptake, increased respiratory capacity, lower blood lactate concentrations, increased mitochondrial and capillary densities and improved enzyme activity.

Anaerobic threshold

The anaerobic threshold, the point at which lactic acid starts to accumulate in the muscles, is considered to be somewhere between 80% and 90% of your maximum heart rate and is approximately 40 beats higher than the aerobic threshold. Your anaerobic threshold can be determined with anaerobic threshold testing.

Speed endurance

Speed endurance is used to develop the coordination of muscle contraction. Repetition methods are used with a high number of sets, a low number of repetitions per set and intensity greater than 85%, with distances covered from 60% to 120% of the racing distance. Competition and time trials can be used in the development of speed endurance.

Example sessions

The following are the different speed endurance sessions with examples for an 800m athlete targeting a sub-two minute 800m.

Pyramids - 200m, 300m, 400m, 300m, 200m (frp) [3', 4', 5', 4']
Up the clock - 600m, 700m, 800m (frp) [8']
Down the clock - 800m, 700m, 600m (frp) [8']
Differentials - 4 x 400m (1st 200m 32", 2nd 200m 28") [8']
Over distance - 4 x 1200m (srp) [8']
Under distance - 2 x (3 x 400m) (frp) [3', 8']
Quality - 3 x 600m (rp) [8']

' = minute, " = seconds, frp = faster than target race pace,
srp = slower than target race pace, rp = target race pace

Strength endurance

Strength endurance develops the athlete's capacity to maintain their muscles' contractile force. All athletes need to build a basic level of strength endurance. Examples of activities to build strength endurance are - circuit training, weight training, hill running, harness running, Fartlek etc.

Effect on the heart

As an endurance athlete, you will develop an enlarged heart. You will have:

Bradycardia - Low resting pulse rate of under 50 bpm
ECG shows ventricular hypertrophy (thickening of the heart muscle wall)
X-ray reveals an enlarged heart
Blood tests show raised muscle enzymes

The above-average person (non-athlete) indicates a probable heart block, hypertension, heart failure, a recent myocardial infarct or cardiomyopathy. Should you need to go to a hospital or see your doctor, you should inform them that you are an endurance athlete.

References

GASTIN, P.B. (2001) Energy system interaction and relative contribution during maximal exercise. Sports Med, 31 (10), p. 725-741
McLELLAN, T. M. and SKINNER, J.S. (1981) The use of the aerobic threshold as a basis for training. Can J Appl Sport Sci. 6 (4), p. 197-201.

Page Reference

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MACKENZIE, B. (1997) Endurance Training [WWW] Available from: https://www.brianmac.co.uk/enduranc.htm [Accessed