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fitness testing | critical swim speed
Critical Swim Speed: This reliable test of aerobic capacity is non-invasive and easy to do.
Various methods of determining optimum training thresholds and adequate measures of aerobic and anaerobic capacity are currently used. These include the assessment of lactate threshold (anaerobic threshold), lactate sprint sets, the onset of blood lactate accummulation (OBLA), the lactate minimum (LM), maximum oxygen consumption (VO2max) and the use of heart-rate sets. The reasons why these tests are used are:
1. to check on any changes the swimmers may experience as a result of the period of training (eg, any enhancement or deterioration in aerobic or anaerobic capacity), and
2. to set specific training intensities which are likely to improve the swimmer's level of competitive fitness.
The lactate threshold (LaT) determination is specifically employed to assess endurance potential and is the point at which blood lactate begins to accumulate above resting levels during exercise of increasing intensity (Wilmore & Costill, 1992). With light to moderate exercise intensity blood lactate remains slightly above resting levels, whereas after more intense efforts lactate accumulates more rapidly. This is illustrated in Figure 1, where the break point in the curve represents the LaT. Controversy surrounding this procedure stems from the fact that the muscles produce lactic acid before the threshold is reached, although it is being removed by slow oxidative muscle fibres; thus a clear break point is not always apparent. Because of this, set lactate values are frequently used. An arbitrary value of 4mM represents the point at which blood lactate accumulation begins and is a standard point of reference known as OBLA.
The lactate minimum (LM) test is another way of identifying the individual anaerobic threshold and has shown promise for prescribing the optimal pace for endurance training (Tegtbur et al, 1993). First, the test requires a high level of blood lactate which can be achieved by performing two 50m sprints. This is followed by a series of five or six 300m swims at gradually increasing speeds. The idea is that normal recovery causes blood lactate concentrations to decrease at test speeds lower than the LM and to increase when it has been surpassed. The LM is the speed at which the rate of entry of lactic acid into the blood exceeds the rate of removal.
Lactate testing is not ideal since it involves blood sampling, requires experienced personnel and can be relatively expensive and time-consuming even though it can give an accurate individual assessment. Nevertheless, there is a need to use objective measures which are non-invasive, require inexpensive equipment, and are yet easy to perform. One such measure is that of Critical Swim Speed (CSS)
Critical Swim Speed (CSS)
The concept of CSS has proven a valid and reliable measure of aerobic capacity (Wakayoshi, 1991). The advantages are that it is non-invasive, practical for all coaches, and the only equipment needed is a stop-watch. It is defined as 'the swimming speed that can theoretically be maintained continuously without exhaustion' (Wakayoshi, 1991). It is the highest sustainable work rate which enables lactate to remain in steady-state (where production equals removal).
In 1991, Wakayoshi swam subjects at six various speeds in a swim flume. The subjects swam until exhaustion at each speed, with the time (T) recorded (in seconds) and the distance (D) calculated (speed x T). A regression line (with the equation D = a + bT) was then plotted between D (in metres) and T. The slope of that line (b) determined the CSS (which is given as speed in m/s) while the intercept on the Y-axis is the Anaerobic Swim Capacity (ASC) (a).
In a second study, Wakayoshi (1992) provided a practical method for coaches to determine CSS in a normal swimming pool. Subjects swam four distances (50m, 100m, 200m and 400m) at maximum pace and the time was recorded in seconds. A regression graph was then plotted and the CSS and ASC determined (see Figure 3). Significant correlations were also found between the CSS in the pool and the velocity at OBLA (V- OBLA), also between V- OBLA and CSS in the flume and CSS in the pool and CSS in the flume. It was then concluded that CSS, which could be determined by a non-invasive method, should be utilised as a standard value for establishing the optimum training intensity in each swimmer.
Ginn (1993a) used two maximum swims to determine the CSS (50m and 400m) and stressed that they should take place during training, from a push start, and not to use competition times. The procedure used to calculate CSS was different to that was Wakayoshi. The following formula was used:
CSS = d2 - d1
----------
t2 - t1
where d2 = 400m, d1 = 50m, t2 = time for 400m, and t1 = time for 50m (in seconds).
The result of this is the CSS which is given in metres per second. (m/s). For example, if a swimmer peforms a 50m in 30.2s and a 400m in 290.5s, CSS is calculated as below:
CSS = 400 - 50
----------------------
290.5 - 30.2
= 350
----------
260.3
= 1.34 m/s
Ginn (1993a) then put forward that the obtained value for CSS can then be used to determine training times for sets of different distances. For example, for a suggested set of 6 x 400m, the time per repetition would be calculated as follows:
Time per repetition = distance required
---------------------------------
CSS = 400m
-----------------------
1.3446 m/s
= 297.49s
= 4min 57.5s
Ginn (1993b) related a lot of his CSS work to actual training programmes and found that it is about 80-85 per cent of maximum 100m swim speed, or 90-95 per cent of 400m swim speed. A system of training intensities was devised and is illustrated in Table 1.
Table 1. A simple system of training intensity levels based on calculations of CSS
Training Level % of speed % of max 400m*
Level 1 75-80 >75
Level 2 80-90 75-85
Level 3 90-100 85-95
Level 4 100 100
Level 5 100-110 105
* These are approximate only and will vary for individual swimmers
This classification system provides intensities which approximate the categories published recently and used in the preparation of Barcelona Gold Medallist Alexandre Popov (Touretski, 1993).
Cooper (1996) studied eight competitive swimmers who were efficient in both the front crawl and breaststroke, and determined the CSS for both strokes. Lactate thresholds were also determined as well as velocity for OBLA (4mM lactate). The three swimming speeds (m.s-1) were then compared and the results are shown in Table 2.
Table 2. Mean parameter values obtained during breaststroke and frontcrawl testing
CSS (m.s-1) Tlac (m.s-1) Vobla (m.s-1)
Breaststroke 1.02 1.03 1.05
Frontcrawl 1.34 1.25 1.32
Tlac = Lactate threshold Vobla = Velocity at obla (4mM)
More recently, Coulson (1997) studied the effects of training on the CSS to find out if aerobic/anaerobic training increases/decreases the CSS (comparing sprinters and middle-distance swimmers) and what variations of maximum swims could be used to determine CSS. Twelve subjects (seven male and five female) were tested at three periods of the swimming season. These were pre-season (September), post-aerobic training (November), and post-anaerobic training (December). Four maximum swims (50m, 100m, 200m and 400m) were used for a regression line to be plotted and CSS calculated. The hypothesis put forward was that aerobic training increases CSS and anaerobic training increases ASC. This was due to the expected 'shifts' in the regression line (ie, making it more or less steep and so altering the slope and the intercept).
The results showed a significant increase in CSS as a result of aerobic training (1.38 m.s-1 to 1.42 m.s-1 was the average for the group as a whole) which was maintained as a result of anaerobic training. This was specifically noticeable in the sprint swimmers compared to the middle-distance swimmers, as they would be more prone to changes in their aerobic capacity due to their high anaerobic composition. Table 3 illustrates the mean CSS for the two groups of swimmers.
Table 3. Mean Critical Swim Speeds for sprinters and middle distance swimmers
sprinters middle distance
CSS(m.s-1) CSS(m.s-1)
Pre-season 1.37
Post-Aerobic 1.43
Post-Anaerobic 1.43
Pre-season 1.40
Post-Aerobic 1.40
Post-Anaerobic 1.41
It was concluded that CSS cold be used by swimming coaches as a sensitive measure of training. If coaches have only a limited time to assess the CSS, how many maximum swims need to be performed? Couldson (1997) examined two, three and four maximum swims and found that the two-trial test of 200m and 400m proved to be the most suitable method for CSS determination compared to the four-trial set (which was classed as the 'gold standard'.)
Conclusions
The use of CSS is a valuable and reliable test of aerobic capacity and is sensitive to changes in training. It is a concept which is practical for all coaches, inexpensive, non-invasive, does not required qualified personnel, and the only piece of equipment needed is a stop-watch.
A step-by-step guide to determining CSS - Standardised warm-up, 1000m choice swim.
Method 1
1 Subjects swim either four maximal swimmers (50m, 100m, 200m, and 400m) or two maximal swims (200m and 400m). Good recovery is important so sufficent rest between swims must be given
2 Swims must be from a push and not a dive start
3 Record the swimmer's time for each swim (in seconds).
4 Plot a graph of distance (in metres) against time (in seconds). Distance on the Y-axis and time on the X-axis (see Figure 3 for illustration).
5 Join the two or four points by means of a straight line
6 Calculate the slope (or gradient) of this line. The figure produced is the CSS and is given in metres per second.
Method 2
1 Swim two maximal swims (400m and 50m only) (Ginn, 1993a and b) from a push and not a dive start
2 Record the time for each swim in seconds
3 Calculate CSS using the formula
4 To determine training times for sets, use the formula
Matthew Coulson, Jeremy Cooper and Don MacLaren
(We would like to thank Martin Mosey, Chief Coach, Borough of Kirklees Swimming Club & Swimming Development Officer for Kirklees, and Colin Stripe, Chief Coach, City of Liverpool Swimming Club, for the pool time and swimmers they provided throughout the studies.)
2. to set specific training intensities which are likely to improve the swimmer's level of competitive fitness.
The lactate threshold (LaT) determination is specifically employed to assess endurance potential and is the point at which blood lactate begins to accumulate above resting levels during exercise of increasing intensity (Wilmore & Costill, 1992). With light to moderate exercise intensity blood lactate remains slightly above resting levels, whereas after more intense efforts lactate accumulates more rapidly. This is illustrated in Figure 1, where the break point in the curve represents the LaT. Controversy surrounding this procedure stems from the fact that the muscles produce lactic acid before the threshold is reached, although it is being removed by slow oxidative muscle fibres; thus a clear break point is not always apparent. Because of this, set lactate values are frequently used. An arbitrary value of 4mM represents the point at which blood lactate accumulation begins and is a standard point of reference known as OBLA.
The lactate minimum (LM) test is another way of identifying the individual anaerobic threshold and has shown promise for prescribing the optimal pace for endurance training (Tegtbur et al, 1993). First, the test requires a high level of blood lactate which can be achieved by performing two 50m sprints. This is followed by a series of five or six 300m swims at gradually increasing speeds. The idea is that normal recovery causes blood lactate concentrations to decrease at test speeds lower than the LM and to increase when it has been surpassed. The LM is the speed at which the rate of entry of lactic acid into the blood exceeds the rate of removal.
Lactate testing is not ideal since it involves blood sampling, requires experienced personnel and can be relatively expensive and time-consuming even though it can give an accurate individual assessment. Nevertheless, there is a need to use objective measures which are non-invasive, require inexpensive equipment, and are yet easy to perform. One such measure is that of Critical Swim Speed (CSS)
Critical Swim Speed (CSS)
The concept of CSS has proven a valid and reliable measure of aerobic capacity (Wakayoshi, 1991). The advantages are that it is non-invasive, practical for all coaches, and the only equipment needed is a stop-watch. It is defined as 'the swimming speed that can theoretically be maintained continuously without exhaustion' (Wakayoshi, 1991). It is the highest sustainable work rate which enables lactate to remain in steady-state (where production equals removal).
In 1991, Wakayoshi swam subjects at six various speeds in a swim flume. The subjects swam until exhaustion at each speed, with the time (T) recorded (in seconds) and the distance (D) calculated (speed x T). A regression line (with the equation D = a + bT) was then plotted between D (in metres) and T. The slope of that line (b) determined the CSS (which is given as speed in m/s) while the intercept on the Y-axis is the Anaerobic Swim Capacity (ASC) (a).
In a second study, Wakayoshi (1992) provided a practical method for coaches to determine CSS in a normal swimming pool. Subjects swam four distances (50m, 100m, 200m and 400m) at maximum pace and the time was recorded in seconds. A regression graph was then plotted and the CSS and ASC determined (see Figure 3). Significant correlations were also found between the CSS in the pool and the velocity at OBLA (V- OBLA), also between V- OBLA and CSS in the flume and CSS in the pool and CSS in the flume. It was then concluded that CSS, which could be determined by a non-invasive method, should be utilised as a standard value for establishing the optimum training intensity in each swimmer.
Ginn (1993a) used two maximum swims to determine the CSS (50m and 400m) and stressed that they should take place during training, from a push start, and not to use competition times. The procedure used to calculate CSS was different to that was Wakayoshi. The following formula was used:
CSS = d2 - d1
----------
t2 - t1
where d2 = 400m, d1 = 50m, t2 = time for 400m, and t1 = time for 50m (in seconds).
CSS = 400 - 50
----------------------
290.5 - 30.2
= 350
----------
260.3
= 1.34 m/s
Ginn (1993a) then put forward that the obtained value for CSS can then be used to determine training times for sets of different distances. For example, for a suggested set of 6 x 400m, the time per repetition would be calculated as follows:
Time per repetition = distance required
---------------------------------
CSS = 400m
-----------------------
1.3446 m/s
= 297.49s
= 4min 57.5s
Ginn (1993b) related a lot of his CSS work to actual training programmes and found that it is about 80-85 per cent of maximum 100m swim speed, or 90-95 per cent of 400m swim speed. A system of training intensities was devised and is illustrated in Table 1.
Table 1. A simple system of training intensity levels based on calculations of CSS
Training Level % of speed % of max 400m*
Level 1 75-80 >75
Level 2 80-90 75-85
Level 3 90-100 85-95
Level 4 100 100
Level 5 100-110 105
* These are approximate only and will vary for individual swimmers
This classification system provides intensities which approximate the categories published recently and used in the preparation of Barcelona Gold Medallist Alexandre Popov (Touretski, 1993).
Cooper (1996) studied eight competitive swimmers who were efficient in both the front crawl and breaststroke, and determined the CSS for both strokes. Lactate thresholds were also determined as well as velocity for OBLA (4mM lactate). The three swimming speeds (m.s-1) were then compared and the results are shown in Table 2.
Table 2. Mean parameter values obtained during breaststroke and frontcrawl testing
CSS (m.s-1) Tlac (m.s-1) Vobla (m.s-1)
Breaststroke 1.02 1.03 1.05
Frontcrawl 1.34 1.25 1.32
Tlac = Lactate threshold Vobla = Velocity at obla (4mM)
More recently, Coulson (1997) studied the effects of training on the CSS to find out if aerobic/anaerobic training increases/decreases the CSS (comparing sprinters and middle-distance swimmers) and what variations of maximum swims could be used to determine CSS. Twelve subjects (seven male and five female) were tested at three periods of the swimming season. These were pre-season (September), post-aerobic training (November), and post-anaerobic training (December). Four maximum swims (50m, 100m, 200m and 400m) were used for a regression line to be plotted and CSS calculated. The hypothesis put forward was that aerobic training increases CSS and anaerobic training increases ASC. This was due to the expected 'shifts' in the regression line (ie, making it more or less steep and so altering the slope and the intercept).
The results showed a significant increase in CSS as a result of aerobic training (1.38 m.s-1 to 1.42 m.s-1 was the average for the group as a whole) which was maintained as a result of anaerobic training. This was specifically noticeable in the sprint swimmers compared to the middle-distance swimmers, as they would be more prone to changes in their aerobic capacity due to their high anaerobic composition. Table 3 illustrates the mean CSS for the two groups of swimmers.
Table 3. Mean Critical Swim Speeds for sprinters and middle distance swimmers
sprinters middle distance
CSS(m.s-1) CSS(m.s-1)
Pre-season 1.37
Post-Aerobic 1.43
Post-Anaerobic 1.43
Pre-season 1.40
Post-Aerobic 1.40
Post-Anaerobic 1.41
It was concluded that CSS cold be used by swimming coaches as a sensitive measure of training. If coaches have only a limited time to assess the CSS, how many maximum swims need to be performed? Couldson (1997) examined two, three and four maximum swims and found that the two-trial test of 200m and 400m proved to be the most suitable method for CSS determination compared to the four-trial set (which was classed as the 'gold standard'.)
Conclusions
The use of CSS is a valuable and reliable test of aerobic capacity and is sensitive to changes in training. It is a concept which is practical for all coaches, inexpensive, non-invasive, does not required qualified personnel, and the only piece of equipment needed is a stop-watch.
A step-by-step guide to determining CSS - Standardised warm-up, 1000m choice swim.
Method 1
1 Subjects swim either four maximal swimmers (50m, 100m, 200m, and 400m) or two maximal swims (200m and 400m). Good recovery is important so sufficent rest between swims must be given
2 Swims must be from a push and not a dive start
3 Record the swimmer's time for each swim (in seconds).
4 Plot a graph of distance (in metres) against time (in seconds). Distance on the Y-axis and time on the X-axis (see Figure 3 for illustration).
5 Join the two or four points by means of a straight line
6 Calculate the slope (or gradient) of this line. The figure produced is the CSS and is given in metres per second.
Method 2
1 Swim two maximal swims (400m and 50m only) (Ginn, 1993a and b) from a push and not a dive start
2 Record the time for each swim in seconds
3 Calculate CSS using the formula
4 To determine training times for sets, use the formula
Matthew Coulson, Jeremy Cooper and Don MacLaren
(We would like to thank Martin Mosey, Chief Coach, Borough of Kirklees Swimming Club & Swimming Development Officer for Kirklees, and Colin Stripe, Chief Coach, City of Liverpool Swimming Club, for the pool time and swimmers they provided throughout the studies.)
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