Trial Outcomes & Findings for High Intensity Interval Training Versus Circuit Training (NCT NCT03700671)

Last Updated: 2020-02-17

Results Overview

Maximal oxygen consumption (ml.kg-1.min-1), as determined during a cardiopulmonary exercise test (CPET) represents the upper limit of aerobic fitness in humans. A low VO2max is associated with a greater risk of premature all-cause and cardiovascular mortality, independent of traditional risk factors and physical activity status. Conversely, increasing VO2max through exercise training may improve cardiometabolic health, quality of life and increase life-expectancy

Recruitment status

COMPLETED

Study phase

Target enrollment

42 participants

Primary outcome timeframe

Baseline and 8 weeks

Results posted on

2020-02-17

Participant Flow

Participant milestones

Participant milestones
Measure	High Intensity Interval Training High intensity interval training (HIIT) was set at \> 85% HRmax. Active recovery was set at 25-50 watts. Sessions were performed using cycle ergometry. High intensity interval training: Participants performed HIIT twice a week for eight weeks. Findings were compared to moderate intensity continuous training which followed the same exercise frequency and duration	Circuit Training The Circuit Training (CT) group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80%. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated. Each station was occupied for three to six minutes depending on session duration with minimal rest in-between. Circuit training: The CT group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80% HRmax twice per week for eight weeks. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated
Overall Study STARTED	21	21
Overall Study COMPLETED	20	19
Overall Study NOT COMPLETED	1	2

Reasons for withdrawal

Reasons for withdrawal
Measure	High Intensity Interval Training High intensity interval training (HIIT) was set at \> 85% HRmax. Active recovery was set at 25-50 watts. Sessions were performed using cycle ergometry. High intensity interval training: Participants performed HIIT twice a week for eight weeks. Findings were compared to moderate intensity continuous training which followed the same exercise frequency and duration	Circuit Training The Circuit Training (CT) group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80%. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated. Each station was occupied for three to six minutes depending on session duration with minimal rest in-between. Circuit training: The CT group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80% HRmax twice per week for eight weeks. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated
Overall Study Lack of Efficacy	1	2

Baseline Characteristics

High Intensity Interval Training Versus Circuit Training

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	High Intensity Interval Training n=21 Participants Perform High intensity interval training twice per week for 8 weeks	Circuit Training n=21 Participants Perform Circuit training twice per week for 8 weeks	Total n=42 Participants Total of all reporting groups
Age, Categorical <=18 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Age, Categorical Between 18 and 65 years	21 Participants n=5 Participants	21 Participants n=7 Participants	42 Participants n=5 Participants
Age, Categorical >=65 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Age, Continuous	42.5 years STANDARD_DEVIATION 12.3 • n=5 Participants	41.2 years STANDARD_DEVIATION 12.9 • n=7 Participants	41.9 years STANDARD_DEVIATION 12.6 • n=5 Participants
Sex: Female, Male Female	10 Participants n=5 Participants	9 Participants n=7 Participants	19 Participants n=5 Participants
Sex: Female, Male Male	11 Participants n=5 Participants	12 Participants n=7 Participants	23 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Asian	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Black or African American	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) White	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	21 Participants n=5 Participants	21 Participants n=7 Participants	42 Participants n=5 Participants
Region of Enrollment United Kingdom	20 Participants n=5 Participants	19 Participants n=7 Participants	39 Participants n=5 Participants
Body mass index	24.4 kg.m-2 STANDARD_DEVIATION 2.3 • n=5 Participants	25.9 kg.m-2 STANDARD_DEVIATION 2.7 • n=7 Participants	25.2 kg.m-2 STANDARD_DEVIATION 2.5 • n=5 Participants
Systolic blood pressure	122 mmHg STANDARD_DEVIATION 14 • n=5 Participants	126 mmHg STANDARD_DEVIATION 11 • n=7 Participants	124 mmHg STANDARD_DEVIATION 12 • n=5 Participants
Diastolic blood pressure	75 mmHg STANDARD_DEVIATION 11 • n=5 Participants	79 mmHg STANDARD_DEVIATION 9 • n=7 Participants	77 mmHg STANDARD_DEVIATION 10 • n=5 Participants
Resting heart rate	68 bpm STANDARD_DEVIATION 12 • n=5 Participants	67 bpm STANDARD_DEVIATION 10 • n=7 Participants	68 bpm STANDARD_DEVIATION 11 • n=5 Participants
Respiratory exchange ratio at VO2max	1.30 unitless STANDARD_DEVIATION 0.12 • n=5 Participants	1.31 unitless STANDARD_DEVIATION 0.12 • n=7 Participants	1.31 unitless STANDARD_DEVIATION 0.12 • n=5 Participants
Heart rate maximum	174 bpm STANDARD_DEVIATION 12 • n=5 Participants	174 bpm STANDARD_DEVIATION 14 • n=7 Participants	174 bpm STANDARD_DEVIATION 13 • n=5 Participants
Maximum oxygen consumption/heart rate	12.8 ml.beat-1 STANDARD_DEVIATION 3.7 • n=5 Participants	13.9 ml.beat-1 STANDARD_DEVIATION 3.9 • n=7 Participants	13.6 ml.beat-1 STANDARD_DEVIATION 3.8 • n=5 Participants
Peak power output	191.9 watts STANDARD_DEVIATION 43.7 • n=5 Participants	209.8 watts STANDARD_DEVIATION 55.2 • n=7 Participants	200.9 watts STANDARD_DEVIATION 49.5 • n=5 Participants

PRIMARY outcome

Timeframe: Baseline and 8 weeks

Outcome measures

Outcome measures
Measure	High Intensity Interval Training n=20 Participants High intensity interval training was set at \> 85% HRmax. Active recovery was set at 25-50 watts. Sessions were performed using cycle ergometry. High intensity interval training: Participants performed HIIT twice a week for eight weeks. Findings were compared to moderate intensity continuous training which followed the same exercise frequency and duration	Circuit Training n=19 Participants The circuit training group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80%. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated. Each station was occupied for three to six minutes depending on session duration with minimal rest in-between. Circuit training: The CT group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80% HRmax twice per week for eight weeks. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated
Maximal Oxygen Consumption (ml.Kg-1.Min-1) Pre Intervention	31.5 ml/kg/min Standard Deviation 7.1	31.4 ml/kg/min Standard Deviation 6.8
Maximal Oxygen Consumption (ml.Kg-1.Min-1) Post Intervention	35.4 ml/kg/min Standard Deviation 7.3	32.4 ml/kg/min Standard Deviation 6.2

SECONDARY outcome

Timeframe: Baseline and 8 weeks

Oxygen consumption at the Ventilatory Anaerobic Threshold ml/kg/min. This measure will assess if individuals can exercise at higher intensities before lactate accumulation, thus becoming 'physiologically efficient

Outcome measures

Outcome measures
Measure	High Intensity Interval Training n=20 Participants High intensity interval training was set at \> 85% HRmax. Active recovery was set at 25-50 watts. Sessions were performed using cycle ergometry. High intensity interval training: Participants performed HIIT twice a week for eight weeks. Findings were compared to moderate intensity continuous training which followed the same exercise frequency and duration	Circuit Training n=19 Participants The circuit training group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80%. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated. Each station was occupied for three to six minutes depending on session duration with minimal rest in-between. Circuit training: The CT group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80% HRmax twice per week for eight weeks. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated
Oxygen Consumption at the Ventilatory Anaerobic Threshold Pre Intervention	15.5 ml/kg/min Standard Deviation 2.7	15.6 ml/kg/min Standard Deviation 3.0
Oxygen Consumption at the Ventilatory Anaerobic Threshold Post Intervention	17.9 ml/kg/min Standard Deviation 2.5	16.2 ml/kg/min Standard Deviation 3.1

OTHER_PRE_SPECIFIED outcome

Timeframe: 8 weeks

Population: To assess the validity of the exercise interventions, participant fidelity to the desired exercise intensity was determined using cut points using specific cut points. Fidelity was measured over the course of the 16 sessions.

To assess if the interventions were delivered as intended, percentage of participants that complied with the exercise protocols

Outcome measures

Outcome measures
Measure	High Intensity Interval Training n=20 Participants High intensity interval training was set at \> 85% HRmax. Active recovery was set at 25-50 watts. Sessions were performed using cycle ergometry. High intensity interval training: Participants performed HIIT twice a week for eight weeks. Findings were compared to moderate intensity continuous training which followed the same exercise frequency and duration	Circuit Training n=19 Participants The circuit training group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80%. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated. Each station was occupied for three to six minutes depending on session duration with minimal rest in-between. Circuit training: The CT group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80% HRmax twice per week for eight weeks. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated
Intervention Fidelity - Participants That Complied With the Exercise Protocols	90 Percentage Interval 80.0 to 100.0	86 Percentage Interval 76.0 to 96.0

OTHER_PRE_SPECIFIED outcome

Timeframe: 8 weeks

Population: A percentage of participants that increased maximal oxygen consumption

If participants had a postive increased in maximal oxygen consumption following the two interventions

Outcome measures

Outcome measures
Measure	High Intensity Interval Training n=20 Participants High intensity interval training was set at \> 85% HRmax. Active recovery was set at 25-50 watts. Sessions were performed using cycle ergometry. High intensity interval training: Participants performed HIIT twice a week for eight weeks. Findings were compared to moderate intensity continuous training which followed the same exercise frequency and duration	Circuit Training n=19 Participants The circuit training group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80%. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated. Each station was occupied for three to six minutes depending on session duration with minimal rest in-between. Circuit training: The CT group completed a practical seven-station mixed modality exercise circuit (cycle ergometer, rower, treadmill, sit to stand, knee to elbow and leg kickback with bicep curl) at an intensity of 60-80% HRmax twice per week for eight weeks. Participants initially performed 20 minutes of CT with duration gradually increased to the desired 40 minutes as tolerated
The Percentage of Individuals That Responsed to the Intervention	100 Percentage	78 Percentage

Adverse Events

High Intensity Interval Training

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Circuit Training

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Stefan Birkett Lecturer in Exercise Science

University of Central Lancashire

Phone: 01772 893325

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place