HIIT Programming: Manipulating the Variables for Maximum Benefit

There are many variables that can be manipulated when prescribing HIIT and each one effects the enjoyment, intensity of work, and benefits of HIIT. There are several methods of prescribing HIIT. One such method is to have clients exercising at an “all out” effort, which is “Rating of Perceived Exertion.” Another method is “Track and Field” where intervals are measured for distance ran, and distance walked for recovery. There is the “Team Sport” method where small sided games are used for training. Most research uses “Heart Rate Based” or percentage of V02max. There are two methods of prescribing recovery, passive and active both of which impact work-out intensity.

Learning Objectives:

1. List the variables that can be changed/manipulated when prescribing high intensity interval training (HIIT).
2. Explain the differences in HIIT programming when using different methods of prescribing HIIT.
3. Describe the disadvantages of using heart based HIIT and the benefits of using RPE training.
4. Compare the effects of using active recovery or passive recovery.

HIIT Prescription

Buchheit and Laursen (2013) suggest there are at least seven variables that can be manipulated when prescribing HIIT:

1. Intensity of work intervals
2. Duration of work intervals
3. Duration of rest intervals
4. Intensity of rest interval – passive (no activity) or active (low intensity activity)
5. Number of work-to-rest intervals
6. Exercise used
7. Equipment used

The manipulation of each variable can impact the metabolic, cardiopulmonary, and/or neuromuscular responses.

When more than one variable is manipulated, responses are more difficult to predict, since the factors are inter-related.  It remains unclear which combination of work-interval duration and intensity is most effective at allowing an individual to spend time exercising at their V02max while controlling for the level of anaerobic work.

Bacon, et al., (2013) performed a meta-analysis to investigate the effectiveness of interval training, or adding intervals to continuous exercise, on improvements in V02max. The nine studies that had the largest increases in VO2max (∼850 L/min) used intervals of 3–5-minutes with 2-minutes rest.

The Track-and-Field Approach to HIIT

Programming HIIT for runners, coaches have traditionally used running speeds based on times for distances ranging from 800-meters to 5000-meters (Billat, 2001). The earliest documented HIIT protocols were used by middle distance runners. Finnish runner, Hannes Kolehmainen (1912) used intervals at race pace of 3:05 minutes with walking recovery. Czech runner, Emil Zatopek (1952) used wind sprints with jog recoveries. Generally, this method is used by experienced coaches and well-trained athletes, for whom best running times are known. The application of the track-and-field method to other sports and fitness is difficult because coaches and fitness professionals do not know running times of non-track athletes or fitness clients.

The Team Sport Approach

Due to specificity of training and tactical and positional requirements of team sports, game-performance conditioning has gained in popularity (Hill-Haas, et al., 2011). Using small sided games or skill-based conditioning is popular for team sports conditioning (Buchheit, et al., 2009). The intensity of small sided games can be manipulated with the time-on-task and changing the rules, the number of players, and court size.

Heart Rate-Based Prescription

Using heart rate zones has been used for many years and is still popular. It is well suited when doing medium intensity continuous exercise; however, its effectiveness for monitoring the intensity of a HIIT work-out may be limited (Laursen and Jenkins, 2002). Heart rate cannot determine the intensity of training done above the intensity associated with exercising at VO2max, on which most research HIIT protocols are based (Laursen and Jenkins, 2002).

This relates to heart rate lag at onset of exercise, which is slower to respond compared with the VO2 response (Cerretelli and Di Prampero, 1971). Moreover, after a work interval, the heart rate continues to be high, which can cause a problem with an overestimation of the work load during recovery periods (Seiler and Hetlelid, 2005).

Rating of Perceived Exertion-Based Prescription

Using rating of perceived (RPE) can be effective because of its simplicity and versatility. The coach or fitness professional can give the time and intensity of the work and rest intervals, and the athlete or client can self-regulate his or her exercise intensity to his or her “comfort” (or lack of comfort) zone.  In HIIT programming, typically the intensity is the maximum work intensity perceived as sustainable (hard to very hard) and is based on the athlete’s or client’s experience, the session goal, and goals of the client. Rating of perceived exertion may reflect ‘‘a conscious sensation of how hard, intense, and strenuous exercise is’’ relative to the physical, biomechanical, and psychological stress during exercise (Marcora, 2011).

Rating of perceived exertion can be a universal ‘exercise regulator’ regardless of type of exercise or equipment. While more research is needed to confirm the efficacy of using RPE for training sessions, it showed the same physiological adaptations as a heart-rate based program during a six-week program with young women (Celine, et al., 2011). Using RPE has limitations however, since it does not allow for precise manipulation of the physiological response to a HIIT session.

However, considering many HIIT research protocols require subjects to train at near maximal, maximal, or above maximal intensities, it is questionable if research subjects, but more importantly fitness clients, can sustain such high intensity work intervals based on heart rate or time at V02max. For instance, Tabata et al. (1997) showed that exercise VO2max was not reached during repeated 30-second cycling bouts with 2-minute passive recovery. Buchheit, et al., (2012) showed that during an all-out HIIT session, most subjects reached values close to (or above) 90 % of their VO2max and heart rate. However, time at VO2max was only 22-seconds on average.

Active, Passive or Heart Rate Recovery?

Duration and intensity of rest may be the most important variables. They are important because in order to maximize work during repeat intervals, recovery is a key requirement. Recovery is done by increasing blood flow to accelerate muscle metabolic recovery, hydrogen ion buffering, potassium transport, and maintaining a minimal level of V02 to reduce the time needed to reach VO2max during subsequent intervals (Billat, 2001).

The benefit of active recovery (performing a low intensity activity, such as walking, after a bout of high intensity training, such as sprinting) has often been measured by changes in blood lactate concentration, but that has little to do with muscle lactate concentration (Krustrup, et al., 2006).  Moreover, blood and muscle lactate do not have a direct relationship with performance capacity (Krustrup, et al., 2006). The current understanding is that active recovery can lower muscle oxygenation and impairs phosphocreatine resynthesis (helps make adenosine triphosphate for muscle contraction) (Buchheit, et al., 2009).  Passive recovery (inactive resting after a bout of high intensity training) is recommended when the rest interval is less than 2–3 minutes. If an active recovery is chosen, rest intervals should last at least 3–4-minutes at a submaximal intensity to allow the maintenance of high-exercise intensity during the following interval (Belcastro and Bonen, 1975).

In some practical applications and research studies, recovery is determined by waiting for the heart rate to lower to a specific number or percentage of HRmax. However, Seiler and Hetlelid (2005) suggest that considering the factors of heart rate recovery, this practice is not very appropriate.

Conclusion

There appears to be seven variables that can be manipulated when prescribing HIIT:

1. Intensity of work intervals
2. Duration of work intervals
3. Duration of rest intervals
4. Intensity of rest interval – passive (no activity) or active (low intensity activity)
5. Number of work-to-rest intervals
6. Exercise used
7. Equipment used

This gives fitness professionals endless options for HIIT programming.

In addition, there are five methods of prescribing HIIT:

1. Track and Field programming where the intervals are based on distance and intensity of running.
2. Sports Team programming where small-sided games are used for the intervals.
3. Heart Rate Based programming where usually the work interval is based on reaching a certain heart zone.
4. Rating of Perceived Exertion programming where intensity is based on the subjective feeling of intensity.
5. Active or Passive recovery.

The research seems to suggest the RPE programming could be the best for fitness clients because rarely do people in fitness classes achieve true maximal intensity as is reported in research studies where intensity is based on a percentage of V02max or heart rate maximum. The research also suggests passive recovery is preferred over active recovery.

References

Bacon, A.P., et al. 2013. VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis. PLoS ONE, 8(9): e73182. doi:10.1371/journal.pone.0073182

Belcastro, A.N., and Bonen, A. (1975) Lactic acid removal rates during controlled and uncontrolled recovery exercise. Journal of Applied Physiology. 39(6):932–936.

Billat, L.V. (2001) Interval training for performance: a scientific and empirical practice: special recommendations for middle and long-distance running. Part I: aerobic interval training. Sports Medicine. 31(1):13–31.

Buchheit, M., and Laursen, P.B. (2013) High-intensity interval training, solutions to the programming puzzle. Part II: anaerobic energy, neuromuscular load and practical applications. Sports Medicine, 43(10):927-54. doi: 10.1007/s40279-013-0066-5.

Buchheit, M., et al. (2012) Performance and physiological responses during a sprint interval training session: relationships with muscle oxygenation and pulmonary oxygen uptake kinetics. European Journal of Applied Physiology. 112(2):767–79.

Buchheit, M., et al. (2009) Game-based training in young elite handball players. International Journal of Sports Medicine. 30(4): 251–258.

Buchheit, M, et al. (2009) Muscle deoxygenation during repeated sprint running: effect of active vs. passive recovery. International Journal of Sports Medicine. 30(6):418–425.

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Cerretelli, P. and Di Prampero, P.E. (1971) Kinetics of respiratory gas exchange and cardiac output at the onset of exercise. Scandinavian journal of respiratory diseases Suppl.:35a–g.

Hill-Haas, S.V., et al. (2011) Physiology of small-sided games training in football: a systematic review. Sports Medicine. 41(3):199–220.

Krustrup, P., et al. (2006) Muscle and blood metabolites during a soccer game: implications for sprint performance. Medicine and Science in Sports Exercise. 38(6):1165–1174.

Laursen, P.B., and Jenkins, D.G. (2002) The scientific basis for high-intensity interval training: optimising training programmes and maximising performance in highly trained endurance athletes. Sports Medicine. 32(1):53–73.

Marcora, S.M. Role of feedback from Group III and IV muscle afferents in perception of effort, muscle pain, and discomfort. Journal of Applied Physiology. 110(5):1499, author reply 1500. doi: 10.1152/japplphysiol.00146.2011.

Seiler, S., and Hetlelid, K.J. (2005) The impact of rest duration on work intensity and RPE during interval training. Medicine and Science in Sports Exercise. 37(9):1601–1607.

Tabata. I., et al. (1997) Metabolic profile of high intensity intermittent exercises. Medicine and Science in Sports Exercise. 29(3):390–395.