Inclusion of sprints in moderate intensity continuous training leads to muscle oxidative adaptations in trained individuals

TY - JOUR

T1 - Inclusion of sprints in moderate intensity continuous training leads to muscle oxidative adaptations in trained individuals

AU - Gunnarsson, Thomas Gunnar Petursson

AU - Brandt, Nina

AU - Fiorenza, Matteo

AU - Hostrup, Morten

AU - Pilegaard, Henriette

AU - Bangsbo, Jens

N1 - CURIS 2019 NEXS 072 © 2019 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

PY - 2019/2/1

Y1 - 2019/2/1

N2 - This study examined adaptations in muscle oxidative capacity and exercise performance induced by two work- and duration-matched exercise protocols eliciting different muscle metabolic perturbations in trained individuals. Thirteen male subjects ((Formula presented.) O2-max 53.5 ± 7.0 mL·kg−1·min−1) (means ± SD) performed 8 weeks (three sessions/week) of training consisting of 60 min of moderate intensity continuous cycling (157 ± 20 W) either without (C) or with (C+S) inclusion of 30-s sprints (473 ± 79 W) every 10 min. Total work performed during training was matched between groups. Muscle biopsies and arm venous blood were collected before as well as immediately and 2 h after exercise during the first and last training session. Plasma epinephrine and lactate concentrations after the first and last training session were 2–3-fold higher in C+S than in C. After the first and last training session, muscle phosphocreatine and pH were lower (12–25 mmol·kg d.w.−1 and 0.2–0.4 units, respectively) and muscle lactate higher (48-64 mmol·kg d.w.−1) in C+S than in C, whereas exercise-induced changes in muscle PGC-1α mRNA levels were similar within- and between-groups. Muscle content of cytochrome c oxidase IV and citrate synthase (CS) increased more in C+S than in C, and content of CS in type II muscle fibers increased in C+S only (9–17%), with no difference between groups. Performance during a 45-min time-trial improved by 4 ± 3 and 9 ± 3% in C+S and C, respectively, whereas peak power output at exhaustion during an incremental test increased by 3 ± 3% in C+S only, with no difference between groups. In conclusion, addition of sprints in moderate intensity continuous exercise causes muscle oxidative adaptations in trained male individuals which appear to be independent of the exercise-induced PGC-1α mRNA response. Interestingly, time-trial performance improved similarly between groups, suggesting that changes in content of mitochondrial proteins are of less importance for endurance performance in trained males.

AB - This study examined adaptations in muscle oxidative capacity and exercise performance induced by two work- and duration-matched exercise protocols eliciting different muscle metabolic perturbations in trained individuals. Thirteen male subjects ((Formula presented.) O2-max 53.5 ± 7.0 mL·kg−1·min−1) (means ± SD) performed 8 weeks (three sessions/week) of training consisting of 60 min of moderate intensity continuous cycling (157 ± 20 W) either without (C) or with (C+S) inclusion of 30-s sprints (473 ± 79 W) every 10 min. Total work performed during training was matched between groups. Muscle biopsies and arm venous blood were collected before as well as immediately and 2 h after exercise during the first and last training session. Plasma epinephrine and lactate concentrations after the first and last training session were 2–3-fold higher in C+S than in C. After the first and last training session, muscle phosphocreatine and pH were lower (12–25 mmol·kg d.w.−1 and 0.2–0.4 units, respectively) and muscle lactate higher (48-64 mmol·kg d.w.−1) in C+S than in C, whereas exercise-induced changes in muscle PGC-1α mRNA levels were similar within- and between-groups. Muscle content of cytochrome c oxidase IV and citrate synthase (CS) increased more in C+S than in C, and content of CS in type II muscle fibers increased in C+S only (9–17%), with no difference between groups. Performance during a 45-min time-trial improved by 4 ± 3 and 9 ± 3% in C+S and C, respectively, whereas peak power output at exhaustion during an incremental test increased by 3 ± 3% in C+S only, with no difference between groups. In conclusion, addition of sprints in moderate intensity continuous exercise causes muscle oxidative adaptations in trained male individuals which appear to be independent of the exercise-induced PGC-1α mRNA response. Interestingly, time-trial performance improved similarly between groups, suggesting that changes in content of mitochondrial proteins are of less importance for endurance performance in trained males.

KW - Faculty of Science

KW - High-intensity interval training (HIIT)

KW - Human performance

KW - Metabolic stress

KW - PGC-1a mRNA

KW - Skeletal muscle single fibers

U2 - 10.14814/phy2.13976

DO - 10.14814/phy2.13976

M3 - Journal article

C2 - 30793541

SN - 2051-817X

VL - 7

JO - Physiological Reports

JF - Physiological Reports

IS - 4

M1 - e13976

ER -