Cardiac Rehabilitation Phase Iii Overload Frequency

Interval Training Program Guide

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Early studies into phase III cardiac rehabilitation (CR) programmes were based on exercise/education sessions that ran three days per week for eight weeks or longer (Jolliffe, et al., 2004). Various studies have been carried out to determine the optimum frequency for cardiac rehabilitation programmes. There is still on-going debate around this topic, but recent literature has shown that two-three times per week, for a minimum of eight weeks, is sufficient to achieve physiological and psychosocial adaptations (SIGN, 2002). It should be emphasised that for patients to gain the optimum physiological and psychosocial benefits they will require prolonged exposure to exercise. Thus phase III should be considered as the minimum time for these changes to occur. The patients and significant others should be strongly encouraged to maintain exercise into phase IV.

How and where phase III programmes are delivered will vary, but they are commonly held in a hospital or, more recently, in the community. The common goal is to encourage life-long adherence to improving and maintaining the individual's exercise habits. By individualising exercise prescription and involving the patients in the exercise consultation process (see Chapter 8), they are more likely to enjoy (E) and adhere (A) on a long-term basis. Benefits to health and fitness can only be achieved if exercise levels are maintained.

Intensity

One of the aims of a cardiac rehabilitation programme is to improve cardiovascular fitness and functional capacity. How hard an individual works to achieve this improvement will be dependent on the individual's current exercise ability, motivation and choice of exercise. Current guidelines recommend that the benefits of a cardiac rehabilitation programme will be gained when exercise intensity is low-to-moderate and designed to suit a range of fitness levels (SIGN, 2002). Recommended intensity for cardiac patients is 60-75% HRmax or 40-60% HRRmax and 12-15 RPE. This will vary according to the risk stratification of the patient, determined during the individual's initial assessment (as described in Chapter 2) and the agreed goals of the patient. Individuals with diminished functional capacity, or who have been identified as a higher risk, should start at a lower intensity (60% HRmax), and progress as able, whereas fitter or lower risk individuals can often work between 65 and 75% HRmax.

Certain medications may alter this prescription. Beta-blockers reduce the sub-maximal and maximal HR, so this will have to be taken into account when developing individualised training zones (see Chapter 3).

Increasing intensity

Depending on the patient, progression of intensity should be guided by the goals of the patient, vocational needs and their risk stratification. When work rate is chosen to increase intensity this can be indicated when there is a noticeable decrease in both HR (>5 beats-min-1) and RPE (>1.5 RPE points) for a known workload. In addition, observation by the exercise leader of the patient, the ease or difficulty of performing the class can add to the decision to increase intensity.

Setting training zones

There are different methods to ascertain training heart rate, and this will be dependent on the information available to the prescriber. Chapter 3 covers in detail setting training zones (see Table 3.1, p. 54) including their strengths and weaknesses. The methods include the following:

• maximal heart rate or peak heart rate;

• Karvonen (Karvonen, et al., 1957) method/heart rate reserve;

• predicted maximal heart rate;

• rating of perceived exertion;

• metabolic equivalents.

As described above, there is a variety of methods for determining the correct exercise intensity a participant should aim to achieve. However, it is essential that the exercise instructors do not neglect their skills of observation. Continual assessment of quality of movement, excessive sweating or shortness of breath, skin colour and general fatigue are indicators for an individual to reduce intensity.

Time

The aerobic conditioning phase of a cardiac rehabilitation programme should last between 20 and 30 minutes (ACPICR, 1999; SIGN, 2002). This does not include the warm-up and cool-down. The CR participant should also be encouraged to be active and to accumulate activity in their everyday activities, as in stage one (Pate, et al., 1995).

Type

There are different ways that the training activity can be delivered. These methods include steady state, circuit interval or free aerobic. The ACSM (1995) define group exercise type or mode, in terms of three classifications:

1. constant in nature, with little variation in effort, where HR can be kept within specific limits, e.g. cycling, rowing;

2. fluctuating involving skilful activities, e.g. cross country skiing;

3. varying with skill and intensity, fluctuating significantly, e.g. competitive sports.

For phase III CR type one and two would be those that achieve the training effects, but also introduce some aspects of motor skill. In addition type two reflects functional activity, where HR does not stay constant, for example, climbing stairs and housework.

Exercise Prescription 140 t—

Exercise Prescription Phase Example

S 80

00:00:00

00:10:00

00:20:00 Time in minutes

00:30:00

00:40:00

Figure 4.1. Heart rate pattern in a steady state exercise. Training heart rate zones between dotted lines.

Steady State Training

Steady state (like group one ACSM [1995]) training type is a sustained activity, where workload and HR are maintained at a constant sub-maximal intensity. Jogging, walking, stepping and cycling are examples of activities that are continuous. Figure 4.1 shows a steady state activity of cycling. The disadvantage of steady state training is that subjects can be bored. In addition, steady state does not represent normal functional activity, and is more difficult to transfer into a home environment.

Circuit Interval Training

In this context a circuit is a number of different exercise stations NOT circuit training. Circuit training involves a number of vigorous exercises that are often strength training in nature. Circuit interval training (like group two ACSM [1995]) involves short duration bursts of activity interspersed with either rest periods, or activity of a less intensive workload or active recovery (AR) stations. Cardiac rehabilitation phase III programmes tend to favour the use of circuit interval training as it allows for individualisation and accommodates different needs and levels of ability. This individualisation can be achieved through:

• changing the duration at each station;

• changing the length of rest periods between each station;

• altering the amount of resistance employed;

• altering the speed and range of movements.

When cardiac rehabilitation classes use circuit interval training, patients work between cardiovascular (CV) stations and active recovery (AR) stations. Each station has a fixed time period, which can range from 30 seconds to three minutes. CV stations should have the patients working up to the higher intensity of 75% HRmax, whereas AR are generally used to increase endurance of specific muscle groups, e.g. quadriceps, and are of a lower intensity, i.e. 60% HRmax. Patients exercise within the different HR and RPE ranges. The ultimate aim is to increase the duration of exercise at the higher intensity exercise stations and reduce the duration at the lower intensity stations. This is achieved by encouraging an increase in the duration of the CV component and a reduction in AR time. To attain overload, an increase in CV time or an increase in exercise intensity can be used. It will depend on the patient whether time or intensity is the more appropriate method to attain increase in overload.

This example shows how progression on a circuit with 5 CV and 5 AR stations can be achieved by increasing time spent at each station:

Circuit One (10 Minutes)

Total CV time = 5 minutes

Total AR time = 5 minutes

Progresses to:

Circuit Two (10 Minutes) AR - 30 seconds CV - 1 minute, 30 seconds Total CV time = 7.5 minutes Total AR time = 2.5 minutes

Progresses to:

Circuit Three (Using 5 CV Stations Only)

CV - 2 minutes

Total CV time = 10 minutes

Total AR time = 0 minutes

In this type of exercise the HR fluctuates and monitoring is more difficult. The advantage of this mode is that it is more representative of daily functional activity. In addition, it is easier for the exercise leader to construct a home

Time in minutes

Figure 4.2. Heart rate pattern in an interval circuit exercise. Training heart rate zones between dotted lines.

Time in minutes

Figure 4.2. Heart rate pattern in an interval circuit exercise. Training heart rate zones between dotted lines.

programme that is similar to this. Figure 4.2 shows HR during circuit interval mode.

Free Aerobic

This type of training involves the exercise leader performing the exercise at the same time as the group and teaching the group at the same time. The class follows the exercise leader's commands and demonstrations. This type of activity is often used in the warm-up part of the class. Free aerobics can provide a large variety of exercises and require very little equipment. A disadvantage is that monitoring and maintaining subjects in their training zones are more difficult. (See Chapter 5 for more on class design.)

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