Our office will remain closed through Friday, September 18th as we continue to assess the damages caused by Hurricane Sally. ActiGraph team members are working remotely, however shipping delays should be expected at this time. We expect to resume regular business hours on Monday, September 21st. If you need immediate assistance, please contact us by email at firstname.lastname@example.org and we will respond as quickly as possible. Thank you for your continued support.
Effect of High-Intensity Interval Training on Cardio-Metabolic Risk Markers in Adolescents: 3-Month Follow-Up of Project FFAB
- Added on July 7, 2012
Introduction Project FFAB is an exploratory controlled before and after study of the effects of a practical and engaging low-volume high-intensity training (HIT) intervention on cardio-metabolic risk markers. The extent to which adaptations to HIT can be maintained is unknown (Gibala & McGee, 2008). We aimed to evaluate the maintenance of any beneficial intervention effects at 3 months follow-up.
Methods Participants were 102 adolescents (64 male; 14.3 ± 0.3 years; mean ± SD) from four schools; two schools were assigned to the Intervention (n = 41) and two to the Control, matching for socioeconomic status. The intervention comprised four sets of 45 s maximal effort exercise (at least 90% of maximum heart rate) involving boxing, dance, soccer and basketball drills, with 90 s rest between sets, up to three times weekly for 10 weeks. The number of sets was increased by one every two weeks. Outcomes were blood lipids and glucose, waist circumference, C-reactive protein, blood pressure, physical activity levels (7-day accelerometry), aerobic fitness (multistage fitness test), and carotid artery intima-media thickness. The difference in the change from baseline (intervention minus control) was estimated for each outcome, with sex, the baseline value, and maturity offset as covariates. Using magnitude-based inferences (MBI) with qualitative probabilistic descriptors (Hopkins et al., 2009), we calculated the probability (P, MBI) that the true population effect was greater than the minimum important difference (MID; 0.2 standard deviations).
Results Compliance was indicated by 75% of the intervention group completing at least 70% of the sessions. At the post-intervention time point, we had previously observed clinically relevant improvements vs. control (’likely’ or ’very likely’ to be greater than the MID) in triglycerides (-24%), waist circumference (-2.7 cm), and mean daily moderate to vigorous physical activity (MVPA) (14.3 min). At 3-months follow-up the mean triglyceride level was 6% lower in Intervention vs. Control (90% confidence interval, -22 to 14%; P, MBI = 0.38), waist circumference was 2.2 cm smaller (-3.4 to -1.1 cm; P, MBI = 0.43), and mean daily MVPA was 12.8 minutes greater (-12.0 to 37.7 minutes; P, MBI = 0.69). All three effects were ’possibly’ important. There was no substantial effect on any other outcome.
Discussion Clinically relevant post-intervention effects were attenuated at 3-months follow up. There is some evidence of a possible residual benefit, but exercise interventions must be regular to maintain beneficial adaptations.
References Gibala MJ, & McGee SL (2008). Exerc Sport Sci Rev, 36:58-63. Hopkins, WG, et al. (2009). Med Sci Sports Exerc. 41:3–13.