Entrenamiento intervalado

1124

Short-term high-intensity interval training improves phosphocreatine recovery kinetics following moderate-intensity exercise in humans
Sean C. Forbes, Jill M. Slade, and Ronald A. Meyer

Abstract: Previous studies have shown that high-intensity training improves biochemical markers of oxidative potential in skeletal muscle within a 2-week period. The purpose of this study was toexamine the effect of short-term high-intensity interval training on the time constant (t) of phosphocreatine (PCr) recovery following moderate-intensity exercise, an in vivo measure of functional oxidative capacity. Seven healthy active subjects (age, 21 ± 4 years; body mass, 69 ± 11 kg) performed 6 sessions of 4–6 maximal-effort 30 s cycling intervals within a 2-week period, and 7 subjects (age, 24 ±5 years; body mass, 80 ± 15 kg) served as controls. Prior to and following training, phosphorous-31 magnetic resonance spectroscopy (31P-MRS; GE 3T Excite System) was used to measure relative changes in high-energy phosphates and intracellular pH of the quadriceps muscles during gated dynamic leg-extension exercise (3 cycles of 90 s exercise and 5 min of rest). A monoexponential model was used toestimate the t of PCr recovery. The t of PCr recovery after leg-extension exercise was reduced by 14% with high-intensity interval training (pretraining, 43 ± 14 s vs. post-training, 37 ± 15 s; p < 0.05) with no change in the control group (44 ± 12 s vs. 43 ± 12 s, respectively; p > 0.05). These findings demonstrate that short-term high-intensity interval training is an effective means ofincreasing functional oxidative capacity in skeletal muscle. Key words: phosphorus magnetic resonance spectroscopy, endurance, oxidative capacity, aerobic capacity. ` ´ ˆ ´ ´ ´ ´ Resume : D’apres des etudes, l’entraınement de forte intensite ameliore en moins de deux semaines les marqueurs biochi´ ˆ miques du potentiel oxydatif du muscle squelettique. Le but de cette etude est d’analyser l’effet del’entraınement par in` ´ ´ ´ ´ tervalle pendant une breve periode de temps et de forte intensite sur la constante de temps (« t ») de la recuperation de la ´ ´ ` ´ ´ ´ ´ phosphocreatine (PCr) consecutivement a un exercice d’intensite moderee et sur la capacite oxydative fonctionnelle mesu´ ´ ´ ree in vivo. Sept sujets en bonne sante et physiquement actifs (21 ± 4 ans (ecart-type); 69 ± 11 kg) participenten moins ` ´ ` ´ ´ de 2 semaines a 6 seances de 4 a 6 efforts maximaux consistant en des exercices de pedalage d’une duree de 30 s; 7 sujets ˆ ´ ` ´ ˆ ´ (24 ± 5 ans; 80 ± 15 kg) jouent le role de temoins. Avant et apres la fin de la periode d’entraınement, on mesure par reso´ ´ ´ nance magnetique nucleaire du phosphore 31 (31P-MRS, « GE 3T Excite System ») les variations relatives des composes ´ ´´ phosphates riches en energie et du pH intracellulaire des muscles quadriceps au cours d’une seance d’exercice d’extension ´ ´ ´ ` dynamique consistant en 3 cycles d’effort d’une duree de 90 s intercale d’un repos d’une duree de 5 min. On recourt a un ` ´ ´ ´ ´ modele monoexponentiel pour estimer le t de la recuperation du PCr. Le t de la recuperation du PCr diminue de 14 % ´ ` ˆ ´ ´ ˆconsecutivement a un entraınement par intervalle de forte intensite : 43 ± 14 s avant la periode d’entraınement comparati` ` ´ ˆ ` ´ vement a 37 ± 15 s apres la periode d’entraınement, p < 0,05; on n’observe aucun changement aupres du groupe temoin, ` ` ˆ soit 44 ± 12 s comparativement a 43 ± 12 s, respectivement, p > 0,05). D’apres ces observations, un entraınement par in´ ´ ´ ´ tervalle de courte dureeet de forte intensite constitue un bon moyen d’ameliorer la capacite oxydative fonctionnelle du muscle squelettique. ´ ´ ´ ´ ´ ´ ´ Mots-cles : resonance magnetique nucleaire du phosphore 31, endurance, capacite oxydative, capacite aerobie. ´ [Traduit par la Redaction]

Received 5 June 2008. Accepted 13 August 2008. Published on the NRC Research Press Web site at apnm.nrc.ca on 3 December...