To calculate the position of the lactate threshold will enable athletes to exercise at the appropriate level. Tesch (1978) identifies that it is beneficial for an athlete to work as close to their lactate threshold to gain maximum performance, although must not cross lactate threshold as will suffer from fatigue and muscle soreness.
An important issue mentioned by Sjödin and Jacobs, is that the physiological build of a body will determine the rate and amount of fatigue that the athlete will endure. Meaning there are two types of muscle fibres, type 1 and type 2. Type 2 fibres have small cluster of capillaries, which are very low in density compared to Type 1 fibres. Astrand and Radahl (1986) proclaim a difference in capillary density and function of myoglobin can affect fatigue. Therefore if OBLA is low and then accumulation of lactate will be apparent in early stages, as efficiency of reducing levels of lactic acid and transporting oxygen are indigent. The purpose of the study was to compare lactate profiles of two sports science students
Method:
Two sport science students volunteered to take part in the experiment. Both of the athletes were training athletes in different sports. The subject’s height and weight were measured. Both the athletes had 4 electrodes connected to them and had a mouthpiece to record respiratory consumption. The warm up was carried out for 5 minutes at 1 % incline on the treadmill this simulates external environment. The subjects were allowed time to familiarise themselves with the treadmill. The speed at which each student warmed up was dependent upon the previous recording of VO2max.
The experiment was intended to last for 4 repeated stages with an increase in speed of 1.1 Km/h at each stage. Each stage lasted 4 minutes with 30 seconds intervals to record 20 micro-litre blood sample, from ear lobe. Every 3 minutes of each stage the subject was asked to indicate the level at which they felt on the Rating of Perceived Exhaustion level. The heart rate was taken in the 4th minute. The sample of blood was collected and centrifuged. An anti –coagulant was added to prevent the blood from clotting. The sample entered the PGM7 analox to analyse the concentration of lactate in the blood. The results were displayed as tables and graphs.
Discussion:
The purpose of the study was to compare the lactate accumulation between two sports science students.
The results showed that subject 1 reach their lactate threshold after 20 minutes into the practical at a speed of 13.7 km/h. the level of lactate was 2.3 mmols/L, which rapidly accumulated 3.6 mmols/L. Subject 2 continued running for 16 minutes until a distinct increase was apparent to represent the lactate threshold at a speed 13.7 km/h. Subject 2 was able to continue performing through high levels of lactate. This indicates that the subject has high tolerance to lactate in the blood and the capability to efficiently abolish the lactate to impede the accumulation. Richardson and Hardman (1989) claimed to obtain high intensity of exercise prior to lactate threshold tends to favour an athlete with the greatest endurance. Therefore subject 1 is the better suited for endurance events.
Subject 1 has low lactate threshold and is able to exercise for longer, which is good as McArdle, Knatch, Knatch (1994) state that high levels of lactate in the blood enhance the risk of fatigue. The results suggest that subject 1 contains vase amounts of type 1 muscle fibres, subject 2 contains predominately type 2 as Wilmore et. al. (1999) explain that type 2 fibres produce considerably more lactate than type 1 fibres. Subject 1 is a rugby player which requires endurance, type 1 muscle fibres and subject 2 is a cricket player therefore demanding type 2 fibres for short sprints. The influence muscle fibres have distinguish the athletes results, this is due to type 1 having a high density of capillaries which suggests greater efficiency in releasing by-product, lactate, compared to type 2 which show signs of difficulty, reported Astrand et. al (1989).
During the experiment each subject’s VO2 was recorded and it calculated that subject 1 worked at 91.8 % of their maximal and subject 2 98.3%. Astrand (1986) identifies that an endurance athlete can exercise closer to their maximal oxygen uptake. It suggests that both subjects are good endurance athletes, subject 2 being superior. The results may have been affected due to subject 2 training hard the night prior to the experiment, meaning that lactate residual was still in blood. Jones states that athletes can exercise at lactate threshold for 50 –60 minutes, therefore it is not a disaster that both athletes peaked early.
If the experiment was to be performed again the speed of warm up would enable the athlete to reach OBLA at the desired time, to eliminate the occurrence of having to continue running. McArdle et, al. (1994) mentions that OBLA and VO2 max are good values of aerobic capacity, which enable athletes to improve their endurance attributes.
Results:
The physical characteristics of the two subjects were both male. Subject 1’s height was 181.8cm and weight 86.4kg, Subject 2’s height 171.3 and weight 69.9kg. The experiment was carried out in the Human Performance Laboratory at St. Mary’s college. The results were displayed as graphs, to compare the level of lactate with the speed and time of each subject. The graph it enables the ability to assess the break point of the lactate threshold, as OBLA was 2 mmols/L. The statistics used in the graph are shown below:
Table. 1.
The results from the graph on the next page indicate that the lactate threshold for subject 1 is at the change of speeds 13.7 to 14.8m/s, at 2.3 mmols/L. At this point subject 1 had been running for 20 minutes with five 30 second breaks. The lactate threshold is quite clear. Subject 2 was erratic, varying in consistency. The lactate threshold was quite high, but was able to distinguish the break point at 4.5 mmols/L, which was close to the OBLA. Subject 2 had been running for 16 minutes with 4 intervals. The results suggest that subject 1 would show great attributes towards endurance exercise as lactate was low therefore able to continue for an immense period at a rapid pace.
Reference List:
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Astrand, P.O., and Rodahl.K. (1986). Textbook of work physiology. Singapore: McGraw-Hill. pp 327
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Jones, A. (1995). Heart rate, lactate threshold and endurance training. Coaching Focus. Vol 33 pp 12-13
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Lamb, D.R. (1984). Physiology of Exercise. New York: Macmillan. pp 139-154.
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McArdle., Knatch & Knatch. (1994). Essentails of Exercise Physiology. United States of America: Williams & Watkins.
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Richardson, S. & Hardman, A. E (1989), Endurance Fitness & Blood Lactate Concentration During stepping Exercise In Untrained subjects, British Journal of Sport Medicine., Vol 23, No.3.
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Sjödin, B and Jacobs, I. (1981). Onset of blood lactate accumulation and marathon running performance. International Journal of Sports Medicine. Vol 22. pp 23-26
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Tesch P., Sjödin B., Karlsson. (1978): Relationship between lactate accumulation, LDH activity, LDH isoenzyme and fibre type distribution in human skeletal muscle. International Journal of Sports Medicine Vol 14. pp 40-46
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Weltman, A, (1995). The blood lactate response to exercise. (Human Kinetics Monograph 4). Leeds: Human kinetics. pp 2-5
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Wilmore, J,. Costill, D (1999) Physiology of Sport and Exercise United States of America: Human Kinetics. pp 136-137.
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