High intensity interval training in a real world setting: a randomized controlled feasibility study in overweight inactive adults, measuring change in maximal oxygen uptake.
BACKGROUND
In research clinic settings, overweight adults undertaking HIIT (high intensity interval training) improve their fitness as effectively as those undertaking conventional walking programs but can do so within a shorter time spent exercising. We undertook a randomized controlled feasibility (pilot) study aimed at extending HIIT into a real world setting by recruiting overweight/obese, inactive adults into a group based activity program, held in a community park.


METHODS
Participants were allocated into one of three groups. The two interventions, aerobic interval training and maximal volitional interval training, were compared with an active control group undertaking walking based exercise. Supervised group sessions (36 per intervention) were held outdoors. Cardiorespiratory fitness was measured using VO2max (maximal oxygen uptake, results expressed in ml/min/kg), before and after the 12 week interventions.


RESULTS
On ITT (intention to treat) analyses, baseline (N = 49) and exit (N = 39) [Formula: see text]O2 was 25.3±4.5 and 25.3±3.9, respectively. Participant allocation and baseline/exit VO2max by group was as follows: Aerobic interval training N =  16, 24.2±4.8/25.6±4.8; maximal volitional interval training N = 16, 25.0±2.8/25.2±3.4; walking N = 17, 26.5±5.3/25.2±3.6. The post intervention change in VO2max was +1.01 in the aerobic interval training, -0.06 in the maximal volitional interval training and -1.03 in the walking subgroups. The aerobic interval training subgroup increased VO2max compared to walking (p = 0.03). The actual (observed, rather than prescribed) time spent exercising (minutes per week, ITT analysis) was 74 for aerobic interval training, 45 for maximal volitional interval training and 116 for walking (p =  0.001). On descriptive analysis, the walking subgroup had the fewest adverse events.


CONCLUSIONS
In contrast to earlier studies, the improvement in cardiorespiratory fitness in a cohort of overweight/obese participants undertaking aerobic interval training in a real world setting was modest. The most likely reason for this finding relates to reduced adherence to the exercise program, when moving beyond the research clinic setting.


BACKGROUND
ACTR.org.au ACTRN12610000295044.
Canterbury District Health Board, Christchurch, New Zealand ; University of Otago Christchurch, Christchurch, New Zealand.
Helen
H
Lunt
University of Canterbury, Christchurch, New Zealand.
Nick
N
Draper
University of Canterbury, Christchurch, New Zealand.
Helen C
HC
Marshall
Canterbury District Health Board, Christchurch, New Zealand.
Florence J
FJ
Logan
Lincoln University, Lincoln, New Zealand.
Michael J
MJ
Hamlin
Christchurch Polytechnic Institute of Technology, Christchurch, New Zealand.
Jeremy P
JP
Shearman
University of Otago, Dunedin, New Zealand.
James D
JD
Cotter
Christchurch Polytechnic Institute of Technology, Christchurch, New Zealand.
Nicholas E
NE
Kimber
University of Canterbury, Christchurch, New Zealand.
Gavin
G
Blackwell
University of Otago Christchurch, Christchurch, New Zealand.
Christopher M A
CM
Frampton
D000328:Adult; D015331:Cohort Studies; D005081:Exercise Therapy; D005240:Feasibility Studies; D006801:Humans; D008875:Middle Aged; D050177:Overweight / Q000503:physiopathology* / Q000628:therapy*; D010101:Oxygen Consumption; D057185:Sedentary Behavior; D016896:Treatment Outcome