December 2018

High-intensity intervals more enjoyable than moderate activity    

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Challenging activity boosts good feelings

By Hank Black

Despite greater rates of perceived exertion teens do not find high-intensity interval exercise (HIIE) unpleasant, and in fact report greater postexercise enjoyment than after completing moderate-intensity interval exercise (MIIE), according to research from the UK.

Interval exercise reflects the normal stop-and-go pattern of playground activity, said lead author Adam A. Malik, a doctoral student at Exeter University in Cornwall, UK. He and colleagues recently explored adolescents’ perceptual responses to HIIE or MIIE during and after exercise.

Their small study (n = 13, mean age = 14 years;  SD = +/- 0.5) looked at affective, enjoyment, and perceived responses. The participants were healthy boys; two had a low level of fitness and one was overweight.

Of three experimental sessions in the laboratory, the first measured physical variables and cardiorespiratory fitness levels and acquainted the participants with the measurement scales. That was followed by two counterbalanced HIIE or MIIE running sessions on a motorized treadmill, separated by a minimum of three days.

Following incremental testing to determine maximum aerobic speed, the running protocol for HIIE involved eight one-minute work intervals at 90% maximum aerobic speed. The MIIE protocol called for between nine and 12 one-minute intervals at 90% ventilatory threshold (VT). The number of MIIE work intervals equaled the distance performed during HIIE for each participant.

High-intensity exercise evoked feelings of excitement and enthusiasm in study participants

Affective responses were measured using the feeling scale (FS) and the felt arousal scale (FAS) at points before, during, and up to 20 minutes after exercise. Enjoyment was rated during the sessions using an exercise enjoyment scale (EES), and immediately and 20 minutes after the protocol using the modified PACES measure. Finally, the rate of perceived exertion (RPE) was measured using the multi-item Pictorial Children’s OMNI questionnaire.

The study found a greater decline in affective valence with HIIE than MIIE but the measure was still positive at the end of the high-intensity work interval (85% positive, 15% negative), whereas all participants in MIIE evoked positive affective responses. During exercise no significant differences on the enjoyment scale were noted between HIIE and MIIE, but HIIE enjoyment was greater immediately after and 20 minutes postexercise. In fact, the researchers found, enjoyment declined 20 minutes after exercise for MIIE, but not for HIIE.

Medicine & Science in Sports & Exercise published the results in May.

The group used a circumplex model to separate dynamic changes arising during HIIE and MIIE. Affective responses were found to remain in the unactivated−pleasant quadrant, which evoked a sense of relaxation during MIIE. During HIIE, however, affective responses moved to the pleasant−activated quadrant, in which excitement and enthusiasm are evoked. Feelings of excitement and enjoyment, the authors stated, appear to be spurred by the participants’ perception that they could complete the HIIT treadmill session when challenged.

Malik said previous studies in this population had confirmed the effectiveness of HIIE in producing health benefits.

“The appeal to adolescents of the high-intensity interval regimen may rest on its positive affect and greater postenjoyment responses compared to one of moderate intensity,” he said. “Data from our study could translate to school-based and other nonlaboratory protocols where inexpensive and practical tools are doubly important.”

He added, “Perceived exertion during HIIE is important to examine due to its role in modulating affective responses and therefore how youths may view physical activity as they age into adulthood.”

This study, he said, also demonstrated the importance of simple psychometric tools such as the FS, EES, and RPE scales to prescribe and monitor the high-intensity protocol.

In previous investigations, adolescents had reported greater enjoyment following intervals of high-intensity exercise compared with continuous exercise of moderate intensity. The current study pointed out, however, that earlier HIIE studies in this population were measured only postexercise, possibly missing important changes during exercise, Malik said. “It is important to employ measurements both during and after exercise to help determine how well adolescents might engage in interval exercise of different intensities,” he said.

As a practical application of the study, Mailk pointed out, the study gathered heart rate responses that may be useful in prescribing intensity levels for protocols used outside the laboratory. Combining this with low-cost and easy-to-use psychometric tools such as FS, RPE, and EES, he said, may provide a strategy to monitor HIIE by teachers and coaches as well as exercise professionals.

HIIT is increasingly promoted for time-challenged adults, and even high-intensity continuous exercise appears to produce beneficial health effects at lower and lower times. Biddle and Batterham, in a seminal 2015 point-counterpoint paper, agreed HIIT results in a broad spectrum of positive cardiometabolic effects but disagreed whether it would be adopted or maintained by many people and therefore have a population-level effect.

Malik and his colleagues maintain their study indicates the practice has genuine potential to contribute to addressing health priorities among adolescents, many of whom may be unable or unwilling to give up a sedentary, digitally leashed lifestyle to engage in more physical activity.

Hank Black is a freelance medical writer in Birmingham, Alabama.

Sources:

Malik AA, Williams CA, Weston KL, et al. Perceptual response2s to high- and moderate-intensity interval exercise in adolescents. Med Sci Sports Exerc 2018 May;50(5):1021-1030.

Biddle SJ, Batterham AM. High-intensity interval exercise training for public health: a big HIT or shall we say HIT it on the head? Int J Behav Nutr Phys Act 2015;12:95.

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