Effect of Low Volume Sprint Interval Training on Cardiorespiratory Fitness
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-55
SponsorCalifornia State University, San Marcos
About this trial
Low levels of physical activity (PA) are related to poor health and greater risk of premature death in adults. Lack of time is cited as a primary barrier to partaking in PA. In the last 20 years, a lot of attention has been directed towards the efficacy of high intensity interval training (HIIT), which consists of brief, intense bursts of PA separated by recovery. One primary benefit of HIIT is a sizable increase in cardiorespiratory fitness (CRF), which enables adults to exercise better and reduce health risks due to the strong link between health status and CRF.
Completion of cardiovascular exercise is typically recommended for all adults to increase CRF, yet it takes a lot of time and may be perceived as boring. Alternatively, HIIT requires less time and tends to cause greater feelings of enjoyment in many adults. Hundreds of studies report an increase in CRF in response to HIIT in various groups of adults ranging from athletes and those with obesity, diabetes, cancer, stroke, and even spinal cord injury, which emphasizes the potency of this vigorous form of PA. Yet, many studies are weakened by a small sample size which questions the feasibility of these findings.
This randomized controlled trial will test the efficacy and feasibility of a very small amount of HIIT, referred to as reduced exertion high intensity interval training (REHIT), in inactive adults. In the proposed study, REHIT will consist of 2 days per week of 1 to two 10 - 20 second sprints on a stationary bike. The proposed sample will include 60 adults who complete 18 sessions of REHIT over a 9 week period, and their responses will be compared to a non exercising control group. During the study, changes in CRF, fuel metabolism, and psychological responses will be monitored, with the latter outcome shedding light on the overall feasibility of HIIT in inactive adults.
Overall, this novel study has profound public health applications as it will assess fitness and health related changes to a small dose of PA in the largest sample to date. If substantial changes in CRF are shown, these data have the potential to modify public health guidelines for implementing PA in inactive adults.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
Healthy
BMI < 35 kg/m2
younger than 56 yr old
no joint issues
Disqualifiers
Those adults who are currently active and not weight stable
Adults with BMI > 35 kg/m2
Use of medications which may alter study outcomes
Trial design
Design model
Parallel
Treatments tested in this trial
High intensity interval training
Other interventionParticipants will complete 24 sessions of REHIT and their responses will be compared to a non exercising control group.
Treatment groups
60 Participants
are divided into 2 treatment groupsGroup A: Intervention groupExperimental treatment 1 intervention
Group B: Non exercising control groupPlacebo comparator 1 intervention
Trial outcomes
Primary outcomes
1
Cardiorespiratory fitness
Cardiorespiratory fitness (CRF) is determined by oxygen transport from cardiovascular system to mitochondria and is strongly related to health status and premature mortality. It will be assessed using VO2max testing on a cycle ergometer and expressed in mL/kg/min.
Time frame
CRF will be assessed at baseline 48 - 72 hours before the start of training, and at 6 and 12 weeks of training, which represent halfway and end of training. The assessments will be performed at least 24 hours after sessions of exercise training.Secondary outcomes
1
Fat and Carbohydrate Oxidation
Substrate metabolism represents the breakdown of fat and carbohydrate for energy expenditure and is related to metabolic health. It is measured during submaximal exercise during which time, participants' expired air is collected continuously. In this study, participants will complete 10 min of low intensity exercise before the VO2max test, and gas exchange data will be acquired to estimate the respiratory exchange ratio (RER) which is used to assess the percent contribution of fat and carbohydrate use. Moreover, fat and CHO oxidation will be calculated from standard equations and expressed in g/min.
Time frame
Fat and carbohydrate oxidation will be measured at baseline before the start of training and at 6 and 12 weeks of training, representing halfway and end of training, and at baseline and at 12 weeks in the non exercising control group.2
Cardiac output
Cardiac output (CO in L/min) refers to the amount of blood delivered by the heart each minute and is the product of stroke volume and HR. Its assessment can shed light on the factors explaining the increase in VO2max with exercise training. In this study, it will be measured noninvasively using thoracic impedance cardiography.
Time frame
CO will be measured at baseline and at 6 and 12 weeks of training, representing halfway and the end of training, and at baseline and at 12 weeks in the non exercising control group.3
Enjoyment of REHIT
The real-world feasibility and efficacy of REHIT has been challenged, as it is thought that this type of vigorous exercise is not enjoyable for adults. One measure related to this is enjoyment, which can be assessed with the 18-item Physical Activity Enjoyment scale. This validated survey is frequently used in similar studies to gauge psychological responses to exercise training. The Physical Activity Enjoyment scale will be completed 5 minutes after sessions of exercise training.
Time frame
This outcome will be assessed during session #2 of each week of training in the exercise training group. So, this outcome will be assessed weekly during all 12 weeks of training.4
Perceived exertion responses to REHIT
The real-world feasibility and efficacy of REHIT has been challenged, as it is thought that this type of vigorous exercise is not enjoyable for adults. One measure related to this is perceived exertion, which can be assessed with the 6 - 20 Borg scale of Rating of Perceived Exertion. This validated survey is frequently used in similar studies to gauge psychological responses to exercise training. This RPE scale will be administered throughout sessions of exercise training, including at baseline, during the warm-up, after sprint 1, midway during recovery, after sprint 2, and then at the end of the exercise session.
Time frame
This outcome will be assessed during session #2 of each week of training in the exercise training group. So, this outcome will be assessed weekly during all 12 weeks of trainingSponsors and contacts
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Source ClinicalTrials.gov