title: Autonomic Function Predicts Fitness Response to Short-Term High-Intensity Interval Training.
abstract: We tested the hypothesis that baseline cardiac autonomic function and its acute response to all-out interval exercise explains individual fitness responses to high-intensity interval training (HIT). Healthy middle-aged sedentary men performed HIT (n=12, 4-6×30 s of all-out cycling efforts with 4-min recovery) or aerobic training (AET, n=9, 40-60 min at 60% of peak workload in exercise test [Loadpeak]), comprising 6 sessions within 2 weeks. Low (LF) and high frequency (HF) power of R-R interval oscillation were analyzed from data recorded at supine and standing position (5+5 min) every morning during the intervention. A significant training effect (p< 0.001), without a training*group interaction, was observed in Loadpeak and peak oxygen consumption (VO2peak). Pre-training supine LF/HF ratio, an estimate of sympathovagal balance, correlated with training outcome in Loadpeak (Spearman's rho [rs]=-0.74, p=0.006) and VO2peak (rs=- 0.59, p=0.042) in the HIT but not the AET group. Also, the mean change in the standing LF/HF ratio in the morning after an acute HIT exercise during the 1(st) week of intervention correlated with training response in Loadpeak (rs=- 0.68, p=0.014) and VO2peak (rs=-0.60, p=0.039) with HIT but not with AET. In conclusion, pre-training cardiac sympathovagal balance and its initial alterations in response to acute HIT exercise were related to fitness responses to short-term HIT.
authors.affiliation: Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland.
authors.forename: A M
authors.initials: AM
authors.lastname: Kiviniemi
authors.affiliation: Department of Exercise and Medical Physiology, Verve Research, Oulu, Finland.
authors.forename: M P
authors.initials: MP
authors.lastname: Tulppo
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: J J
authors.initials: JJ
authors.lastname: Eskelinen
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: A M
authors.initials: AM
authors.lastname: Savolainen
authors.affiliation: Paavo Nurmi Centre, Turku, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Kapanen
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: I H A
authors.initials: IH
authors.lastname: Heinonen
authors.affiliation: Department of Exercise and Medical Physiology, Verve Research, Oulu, Finland.
authors.forename: A J
authors.initials: AJ
authors.lastname: Hautala
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: J C
authors.initials: JC
authors.lastname: Hannukainen
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: K K
authors.initials: KK
authors.lastname: Kalliokoski
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D005080:Exercise Test; D006321:Heart / Q000294:innervation; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010806:Physical Education and Training / Q000379:methods*; D010809:Physical Fitness / Q000502:physiology*