title: The Physiological Mechanisms of Performance Enhancement with Sprint Interval Training Differ between the Upper and Lower Extremities in Humans.
abstract: To elucidate the mechanisms underlying the differences in adaptation of arm and leg muscles to sprint training, over a period of 11 days 16 untrained men performed six sessions of 4-6 × 30-s all-out sprints (SIT) with the legs and arms, separately, with a 1-h interval of recovery. Limb-specific VO2peak, sprint performance (two 30-s Wingate tests with 4-min recovery), muscle efficiency and time-trial performance (TT, 5-min all-out) were assessed and biopsies from them. vastus lateralisandm. triceps brachiitaken before and after training. VO2peak and Wmax increased 3-11% after training, with a more pronounced change in the arms (P< 0.05). Gross efficiency improved for the arms (+8.8%,P< 0.05), but not the legs (-0.6%). Wingate peak and mean power outputs improved similarly for the arms and legs, as did TT performance. After training, VO2during the two Wingate tests was increased by 52 and 6% for the arms and legs, respectively (P< 0.001). In the case of the arms, VO2was higher during the first than second Wingate test (64 vs. 44%,P< 0.05). During the TT, relative exercise intensity, HR, VO2, VCO2, VE, and Vtwere all lower during arm-cranking than leg-pedaling, and oxidation of fat was minimal, remaining so after training. Despite the higher relative intensity, fat oxidation was 70% greater during leg-pedaling (P= 0.017). The aerobic energy contribution in the legs was larger than for the arms during the Wingate tests, although VO2for the arms was enhanced more by training, reducing the O2deficit after SIT. The levels of muscle glycogen, as well as the myosin heavy chain composition were unchanged in both cases, while the activities of 3-hydroxyacyl-CoA-dehydrogenase and citrate synthase were elevated only in the legs and capillarization enhanced in both limbs. Multiple regression analysis demonstrated that the variables that predict TT performance differ for the arms and legs. The primary mechanism of adaptation to SIT by both the arms and legs is enhancement of aerobic energy production. However, with their higher proportion of fast muscle fibers, the arms exhibit greater plasticity.
authors.affiliation: Department of Sport Science, Julius Maximilians University WürzburgWürzburg, Germany; Swedish Winter Sports Research Centre, Mid Sweden UniversityÖstersund, Sweden.
authors.forename: Christoph
authors.initials: C
authors.lastname: Zinner
authors.affiliation: Research Institute of Biomedical and Health Sciences (IUIBS) and Department of Physical Education, University of Las Palmas de Gran Canaria Las Palmas, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Morales-Alamo
authors.affiliation: Swedish Winter Sports Research Centre, Mid Sweden UniversityÖstersund, Sweden; Institute of Sports Science and Clinical Biomechanics, University of Southern DenmarkOdense, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Ørtenblad
authors.affiliation: Swedish School of Sport and Health Sciences Stockholm, Sweden.
authors.forename: Filip J
authors.initials: FJ
authors.lastname: Larsen
authors.affiliation: Department of Medical and Health Sciences, Linköping University Linköping, Sweden.
authors.forename: Tomas A
authors.initials: TA
authors.lastname: Schiffer
authors.affiliation: Swedish Winter Sports Research Centre, Mid Sweden University Östersund, Sweden.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Willis
authors.affiliation: Research Institute of Biomedical and Health Sciences (IUIBS) and Department of Physical Education, University of Las Palmas de Gran Canaria Las Palmas, Spain.
authors.forename: Miriam
authors.initials: M
authors.lastname: Gelabert-Rebato
authors.affiliation: Research Institute of Biomedical and Health Sciences (IUIBS) and Department of Physical Education, University of Las Palmas de Gran Canaria Las Palmas, Spain.
authors.forename: Mario
authors.initials: M
authors.lastname: Perez-Valera
authors.affiliation: School of Kinesiology, University of British Columbia Vancouver, BC, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Boushel
authors.affiliation: Research Institute of Biomedical and Health Sciences (IUIBS) and Department of Physical Education, University of Las Palmas de Gran CanariaLas Palmas, Spain; School of Kinesiology, University of British ColumbiaVancouver, BC, Canada.
authors.forename: Jose A L
authors.initials: JA
authors.lastname: Calbet
authors.affiliation: Swedish Winter Sports Research Centre, Mid Sweden UniversityÖstersund, Sweden; School of Kinesiology, University of British ColumbiaVancouver, BC, Canada; School of Sport Sciences, UiT Arctic University of NorwayTromsø, Norway.
authors.forename: Hans-Christer
authors.initials: HC
authors.lastname: Holmberg
keywords: high-intensity training; lower body; performance; triceps brachii; upper body