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August 29, 2014, 12:00AM PT in Exam Preparation Blog  |  0 Comments

Practical Application of the ACE IFT Model: Cardiorespiratory Training: Phase 2

Running on treadmill

Phase 2: Aerobic Efficiency Training

Before a client can progress to or begin in Phase 2, they must be able to, at a minimum, comfortably complete at least 20 to 30 minutes of consistent steady state exercise in zone 1.  Cardiorespiratory exercise in this phase introduces the use of intervals to improve aerobic efficiency training, fitness and health. The main focus is increasing time of cardiorespiratory fitness, while introducing intervals to initially challenges clients at the lower end of zone 2 before progressing to the upper end.

By the time your client is ready to progress to Phase 2, they should have developed an aerobic base during Phase 1. For additional gains, you may need to evaluate your client’s particular cardiorespiratory goal, such as improving or maintaining overall health and fitness. For clients seeking to achieve a onetime competitive goal, using Phase 2 training guidelines may be beneficial. For more competitive goals that prove to be more challenging, progressing to Phase 3 is appropriate. Training in Phase 2 is generally adequate for clients who want to improve or maintain their cardiorespiratory fitness. If your client does not desire to achieve performance-based goal, there may not be a need to progress to the next phase. Always consider your clients’ goals when designing and progressing their programs.

Important Factors to Consider When Programming in Phase 2

  • Before starting in Phase 2, perform a submaximal talk test to determine HR at VT1
  • Utilize this HR for programming throughout this phase
  • Reassess periodically as fitness improves to determine if HR has increased, and if adjustments in intensity is needed 
  •  Objectives in this phase include enhancing aerobic efficiency, introducing zone 2 intervals, and increasing duration and frequency of sessions when possible
  • Warm-up, cool-down and recovery intervals are performed below VT1 to continue advancing in the aerobic base
  • Aerobic intervals above VT1 are introduced, with the goal of improving aerobic efficiency by increasing the intensity of exercise performed at VT1
  • Intervals should start out brief, about 60 seconds, with an approximate hard-to-easy ratio of 1:3 and then progressing to 1:1.
  • Duration of intervals can be increased based on your client’s goals. Progress over several weeks, cautiously, taking into account the client’s fitness level.
  • Increase exercise load by no more than 10% per week.
  • Progress zone 2 intervals by increasing the time of each interval. Move toward a 1:1 ratio.
  • As the client progresses, intervals can progress to the upper end of zone 2. Progress first to longer intervals, then move to a 1:1 ratio.
  • You may progress your client to Phase 3 once he or she has reached seven or more hours a week of cardiorespiratory training or if a performance goal is desired.
  • VT2 is not measured in this phase.

Remember that before your client can progress to Phase 2 they must show success in the aerobic phase. Some clients may not desire to accomplish performance-based goals, so they may choose to remain in Phase 2. Phase 2 provides enough variability for your clients who do not desire to progress to more advance performance goals. If you client has an advanced or performance-related goal, perform the VT2 threshold test to progress to Phase 3. 

Click here to learn about Phase 1: Aerobic Base Training.

By Makeba Edwards


Makeba is a Study Assistance Representative for ACE, and holds a B.S. in Exercise Science and Sports Studies. She is an ACE Certified Personal Trainer Group Fitness Instructor. She also a Les Mills Certified Group Fitness Instructor and teaches several modalities.

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