The Effects of High Intensity Circuit Training in Nature Vs. Indoor on Exercise Performance, and Wellbeing
Condition: Green Exercise; Indoor Exercise
Study type: Interventional

Summary: 
      Exercising in a nature setting has been credited with benefits for health and well-being,
      more so than exercising indoors. Additionally, motoric performance in the same exercise
      (e.g., running speed, more strenuous physical activity) has been reported in some studies to
      be greater if practiced outdoors, in a nature setting. The explanation may be in the inherent
      variability of natural landscapes, the textures, elevations, obstacles and objects which are
      not found in standard built and indoor settings. Indoor settings are characterized by safe,
      organized, patterned textures and objects created for specific ends, which inhibit
      variability in physical and physiological behavior. Variability in the environment turns into
      variability in body systems, which benefits health, well-being, and skill acquisition.

      Variability in behavior depends also on the task. Running or walking is essentially a journey
      throughout the environment in which interaction with obstacles, puddles, and other runners is
      part of the variability of the activity. On the other hand, physical activity such as HICT is
      done in a small area, and is a scripted, prescribed activity (e.g., push-ups, sit-ups), which
      lowers the amount of variability in behavior. The aim of this trial is to test if a low
      variability activity shows differences in performance, wellbeing, and behavior measures
      according to the amount of variability in the environment.

      In this trial the participants will engage in two high intensity circuit training (HICT)
      interventions - one in an indoor setting, and another in a nature setting. The HICT
      intervention includes 12 calisthenic exercises, and will be performed at a self-selected
      intensity by the participants. Each exercise will be performed during one minute, followed by
      30 seconds of rest where the participants will be instructed what the next exercise will be.
      Before exercising, the participants put a heart rate monitor and two inertial measurement
      units (IMUs) on the right arm and leg, according to the correct usage guidelines, and rate
      their positive affect, arousal, and perceived exertion. Immediately after exercising, they
      rate the same measures again.

      Research Hypotheses:

      Greater movement variability, heart rate variability, performance, wellbeing, and arousal
      during HICT in nature setting than indoor setting.
    

Detailed description: 
      Introduction: Nature environments are "any outdoor spaces that retain noticeable elements of
      nature, ranging from pristine or seminatural areas to urban green or blue spaces, including
      green infrastructure". Exercising in nature settings has been shown to improve well-being
      outcomes such as lower anxiety and greater positive mood, more so than exercising in
      artificial environments like urban spaces or indoors.

      Over the past decades, the well-being benefits of nature-based exercise have been extensively
      reported in the literature, but exercise and sport performance have not been studied as much,
      in spite of some studies showing that performance may be better in natural settings than
      indoor conventional settings (e.g., dancing more vigorously, more power in cycling, ability
      to run more distance until exhaustion). This raises the question of how nature may impact
      performance efficacy (the product of performance, i.e., running faster) and efficiency (the
      psychological and physiological processes that may enhance performance efficacy) in exercise
      and sport activities, especially since many studies show, for example, that achieving the
      same goal in nature is less effortful than doing the same activity indoors.

      The relationship between the exercise factor and the environment factor for potential health
      and performance benefits can be seen as sub-additive (less than total independent benefits of
      both exposures), additive (equal to the sum of the parts), and synergistic (greater than the
      sum of the parts).

      Mechanisms: The mechanism by which physical activity in nature environments induces greater
      health and may enhance performance is not yet fully understood. Historically, the exercise
      and sport communities have created "proper" spaces to undertake their physical activities,
      such as gyms, stadiums, tracks. However, these standardized and artificial spaces are
      believed to offer limited variability in action. The ecological dynamics perspective views
      nature settings as a more varied and challenging landscape of affordances (possibilities for
      action) than that of built environments. Variability in the environment turns into
      variability in body systems, allowing for degenerate behavior (changing movement structure
      without compromising functionality). Assuming that the nature environment presents a richer
      and more variable landscape of affordances to exercisers has given birth to a theory within
      the ecological dynamics framework, labelled EVA, or the Empowering Variability of Affordances
      of Nature. To this end, EVA assumes that the uneven surfaces, objects and obstacles of nature
      settings such as grassland and trees allow for more variable athletic behavior, which has
      been deemed beneficial for exercise and sport performance. It must not be a coincidence that
      activities mostly practiced in natural environments such as extreme sports, are notorious for
      their demand for adaptability and creativity, and for promoting health.

      Furthermore, for exercisers, the nature environment is known to elicit
      dissociative/exteroceptive attentive focus (i.e., focus on the environment), while the
      built/indoor environment elicits associative attentive focus (i.e., focus on the task
      itself). An associative cognitive process (focus on the task) is known to cause lower
      affective responses and greater exertion during exercise, particularly in high intensity
      physical activities. In short, exercising in nature may improve wellbeing and athletic
      performance due to inherent variability in action, and by eliciting exteroceptive attentive
      focus.

      Need for a trial: Variability in behavior depends also on the task. Running or walking is
      essentially a journey throughout the environment in which interaction with obstacles,
      puddles, and other runners is part of the variability of the activity. However, HICT is done
      in a small area, and is a scripted, prescribed activity, lowering the amount of variability
      in behavior (e.g., push-ups, sit-ups). Thus, the aim of this study is to test if a closed
      circuit, scripted, anaerobic exercise (HICT) shows differences in movement variability,
      performance, and wellbeing, depending on the exercise environment (nature vs. indoor), in
      healthy, fit adults.

      Familiarization session: Each participant goes individually to the Sport Expertise Laboratory
      (Spertlab) in Faculdade de Motricidade Humana and delivers the Informed Consent. The
      investigator then places the chest band (Polar H10) on the participant according to the
      correct usage guidelines, for familiarization purposes.

      The participant is then shown and instructed on the Greenness Rating Scale and International
      Physical Activity Questionnaire (baseline questionnaires), followed by the Feeling Scale,
      Felt Arousal Scale, and Rating of Perceived Exertion (pre- and post-exercise measurement
      scales). Then the investigator demonstrates all the exercises planned for the exercise
      sessions, explaining to the participant the correct way to perform each one. The
      investigators remind that the participant should not exercise for 24 hours before the
      exercise sessions, and schedule two exercise sessions 48 hours apart (to prevent carry-over
      effects) in the following two weeks. Finally, the investigators collect the chest band and
      inform the participants that they must avoid ingesting caffeine, alcohol, and practicing high
      intensity physical activity in the 24 hours prior to the intervention sessions, and avoid
      ingesting food and liquids (except water) in the 3 hours prior to the sessions.

      Placement of the Inertial Measurement Units (IMUs): Two IMUs are placed at the midpoint
      between the lateral epicondyle and the greater tubercle of the humerus, and between the
      lateral epicondyle and the greater trochanter of the femur, both on the right side. The upper
      (UL) and lower limbs (LL) are the body segments with greater activity during these
      calisthenic exercises; additionally, the proximal segment of the limbs is biarticular and
      does not run the risk of being fixed to the ground, as is the case of the hands/forearms
      during push-ups, and the feet/legs during squats, which would reduce the range of motion, and
      consequently have lesser detectable acceleration.

      Intervention: As the exercise session approaches, the investigators get in touch to remind
      the participants about the session, to bring comfortable clothes (sports equipment). On the
      appointed day and time, the investigators and the participants meet at Faculdade de
      Motricidade Humana (FMH), and are escorted to the exercise site (Spertlab if indoor, Jamor
      park if outdoor). The investigators place the IMUs and the chest band on the participants as
      defined, deliver the Greenness Rating Scale, Feeling Scale, Felt Arousal Scale, and Rating of
      Perceived Exertion (available on a tablet or paper support) and inform participants that they
      can exercise at whatever pace they wish. The exercise session is made of 12 calisthenic
      exercises and is 20 minutes long (60 seconds active and 30 seconds resting per exercise),
      including warm-up and cool-down. The exercise session intervention will be conducted by a
      certified fitness instructor who will not know the objectives of the study (blinding).
      Exercise times will be controlled by the instructor, who will remind and if needed
      demonstrate to the participants what the next exercise is during the rest periods.
      Immediately after performing the exercises, before cool-down, participants complete the
      Rating of Perceived Exertion, and after returning to calm, they complete the remaining
      post-exercise questionnaires, and the investigators collect the chest bands and IMUs. After
      the session, the investigators accompany the participants again to FMH, confirm the next
      session in a minimum of 48 hours, and answer any queries. Participants who performed the
      indoor session will do the next session outdoors, and vice versa.
    

Intervention name(s): High Intensity Circuit Training
Intervention type(s): Behavioral
Intervention description(s): The participants will execute a 12-exercise High Intensity Circuit Training protocol. Each exercise will have an active part taking 30 seconds, in which exercisers are encouraged to do as many repetitions as possible, and a resting part taking 10 seconds in which the participants rest and are informed of the next exercise. Before and after the 12-exercise routine, the participants rate their affect, arousal and perceived exertion, while using a heart rate monitor and two IMU sensors on their arms and legs.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: This trial is designed as a randomised, controlled, participant blinded, superiority trial with two groups. Randomization will be performed as block randomization with a 1:1 allocation.
Masking: Double (Participant, Care Provider)
Primary purpose: Basic Science
Keywords: Nature-based exercise; Indoor exercise; High Intensity Circuit Training; Performance; Movement Variability; Affect; Perceived exertion; Heart Rate Variability; Arousal