Endurance Training – Lower Limb
Mode | Intensity | Duration | Frequency | Type
High training intensities have been shown to elicit the greatest training responses.
Walking training intensity: It is recommended that for walking training a starting intensity should be 80% of the average 6MWT speed (see below how to calculate walking intensity from the results of a 6MWT) or 75% of the peak speed achieved on the ISWT (see below how to calculate walking intensity from the results of a ISWT).
Cycle training intensity: It is recommended that a starting intensity for cycle training should be 60% of peak cycle work rate. In many settings, the peak cycle work rate will not have been measured and exercise intensity may be titrated based on achieving a dyspnoea score or rate of perceived exertion score (RPE) of 3 to 4 on the BORG 0-10 scale.
A. Prescribing intensity based on exercise test results
The results of a six-minute walk test (6MWT) or an incremental shuttle walk test (ISWT) can be used to prescribe training intensity for a walking program (walking laps or walking on a treadmill) and a stationary cycle program. The calculations and examples for prescribing exercise intensity are provided below.
- Exercise intensity for walking laps – based on 6MWT
To calculate an appropriate intensity for walking laps: 80% ([6MWD ÷ 6] x prescribed duration) |
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Six-minute walk distance (6MWD) ÷ 6 = Distance in one minute |
For distance in 30 minutes = one minute distance x 30 |
For distance in 20 minutes = one minute distance x 20 |
For distance in 10 minutes = one minute distance x 10 etc…
Note: The patient would not be expected to keep up the same walking pace throughout the walking training session that they achieved in the 6MWT. Therefore, prescribe approximately 80% of the calculated distance. |
Example:
If the patient walked 220 m in six minutes:
- One minute distance = 220 ÷ 6 = 36.7 m.
- 30 minute distance = 36.7 x 30 = 1100 m.
- 80% of 1100 = 880 m in 30 minutes.
If the distance of the walking track is known, the coordinator can translate this distance into a lap count. Patients may find it easier to count the number of laps they need to walk, rather than the number of metres.
As an example, if the walking track is 32 m then the patient needs to walk 27.5 laps in 30 minutes (i.e. 880 ÷ 32 = 27.5 laps, prescribe 27 or 28 laps).
Tip: Translate the prescribed walking distance into a distance the patient is familiar with.
At the beginning of a program, patients (particularly those who have been sedentary) may not be able to walk continuously for 30 minutes. These patients should aim to start with 10 minutes of continuous walking, and build up to 30 minutes.
From the above example, if a 10-minute exercise session is deemed necessary at the start of the program, then this patient would need to walk 293 m (i.e. 880 m ÷ 3 = 293 m, rounded to 300 m).
- Exercise intensity for walking on a treadmill – based on 6MWT
To calculate an appropriate intensity for walking on a treadmill: Treadmill speed = 80% (6MWT average speed) |
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Treadmill speed = 80% 6MWT average speed
6MWT average speed = (6MWT distance x 10) ÷ 1000 km / hr Note: The treadmill speed may need to be set 0.5 – 1.0 kph slower than calculated due to the unfamiliar nature of treadmill walking compared to walking on a flat track. However, walking speed is usually never below 2kph when walking on a treadmill as speeds below this are difficult due to balance problems and do not represent efficient walking speeds. |
Example:
If the patient walked 300 m in the 6MWT, then:
- 300 x 10 ÷ 1000 = 3.0 km / hr.
- 80% of 3.0 km / hr = 2.4 km / hr.
Therefore, the initial treadmill speed would be set at 2.4 km / hr. The treadmill may start at approximately 2 km/hr to account for the patient being unfamiliar with treadmill walking.
- Exercise intensity for walking laps – based on ISWT
The distance that the patient walked during the ISWT can be used to determine the walking speed for that patient’s walking program.
Use the table below to find the distance (m) that the patient walked and the corresponding walking speed (km/h).
Level | Speed | Distance | Predicted VO_{2} peak | Time / shuttle | Number of shuttles | ||
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m/s | km/h | m | ml/kg/min* | s | level | total | |
1 | 0.50 | 1.80 | 0-30 | 4.4-4.9 | 20.00 | 3 | 3 |
2 | 0.67 | 2.41 | 40-70 | 5.2-5.9 | 15.00 | 4 | 7 |
3 | .084 | 3.03 | 80-120 | 6.2-7.2 | 12.00 | 5 | 12 |
4 | 1.01 | 3.63 | 130-180 | 7.4-8.7 | 10.00 | 6 | 18 |
5 | 1.18 | 4.25 | 190-250 | 8.9-10.4 | 8.57 | 7 | 25 |
6 | 1.35 | 4.86 | 260-330 | 10.7-12.4 | 7.50 | 8 | 33 |
7 | 1.52 | 5.47 | 340-420 | 12.7-14.7 | 6.67 | 9 | 42 |
8 | 1.69 | 6.08 | 430-520 | 14.9-17.2 | 6.00 | 10 | 52 |
9 | 1.86 | 6.69 | 530-630 | 17.4-19.9 | 5.46 | 11 | 63 |
10 | 2.03 | 7.31 | 640-750 | 20.22-22.9 | 5.00 | 12 | 75 |
11 | 2.20 | 7.92 | 760-880 | 23.2-26.2 | 4.62 | 13 | 88 |
12 | 2.37 | 8.53 | 890-1020 | 26.4-30.2 | 4.29 | 14 | 102 |
*VO_{2}peak (ml/kg/min) = 4.19 + (0.025 x distance {m})
Patients would not be expected to walk at the peak speed shown on the table during their 30-minute endurance exercise training session. Therefore, only 75% of the peak speed should be prescribed as the walking speed (exercise intensity) for training. At 75% of peak speed, the patient will be walking at approximately 60% of their predicted peak VO_{2}.
At the beginning of a program, patients (particularly those who have been sedentary) may not be able to walk continuously for 30 minutes. These patients should aim to start with 10 minutes of continuous walking, and build up to 30 minutes.
If the distance of the walking track is known, the coordinator can translate this distance into a lap count. Patients may find it easier to count the number of laps they need to walk, rather than the number of metres.
Example:
If the patient walked 190 to 250 m during the ISWT, then:
- The peak walking speed (as shown on the table) would be 4.25 kph (Level 5)
- The training walking speed would be 75% of the peak speed 75% of 4.25 kph = 3.2 kph
- Therefore, in one hour, the patient would be expected to walk 3.2 km
- For a 30 minute training walk, the patient would walk 1.6 km
- For a 20 minute training walk, the patient would walk approximately 1 km
- For a 10 minute training walk, the patient would walk 0.5 km
- The distance can be converted to number of laps. If the patient’s walking track was 32 m, then the patient would need to complete 31 laps within a 20-minute training walk session
1000 m ÷ 32 = 31 laps
B. Prescribing intensity based on dyspnoea assessments.
Research shows that levels of dyspnoea in patients with COPD can equate to levels of oxygen consumption. Therefore, the patient’s level of dyspnoea may be used to monitor exercise intensity.
Most clinicians encourage their patients to exercise at a dyspnoea score of about 3 (“moderate”) as this equates to exercising at a cycle training intensity of approximately 75% VO_{2} peak. Therefore, patients could be encouraged to exercise at this level of dyspnoea.
The use of the dyspnoea score can help patients equate the level of exercise that they perform during the supervised program to the level of exercise that they have been asked to perform during their home program. If they maintain a similar level of dyspnoea, they should be exercising at a similar intensity.
C. Prescribing exercise intensity for cycling based on 6MWT or ISWT
The recommended intensity when prescribing cycle ergometry training is at least 60% of the peak work rate achieved on an incremental symptom-limited cycle ergometry test. However, clinically many patients do not undergo a cycle ergometry test.
Several published equations are available to estimate the initial work rate for prescribing cycle ergometry training based on the performance of a patient with COPD on the 6MWT or ISWT. However, for an individual patient, the different equations may give different estimates of peak work rate and thus different intensities for training (prescribed at a %peak work rate). These equations have not been prospectively validated and their utility in the clinical setting has not yet been tested (see Arnadottir 2007, Hill 2008 and Luxton 2008).